The study, led by Shang Jiang and Peixin Zhu of the State Key Laboratory of Catalysis at the Dalian Institute of Chemical Physics, together with Yanting Liu and Dehui Deng, describes a coupled process the authors call seawater-to-hydrogen-and-water, or STHW. Rather than treating desalination and electrolysis as separate, serial industrial steps, the design folds them into a single thermally integrated loop. Low-grade waste heat released by the alkaline electrolyser—heat that would normally be dissipated into the environment as a loss—is captured and used to drive low-temperature distillation of seawater. The distilled water then serves two purposes simultaneously: it replenishes the electrolyser’s feedwater and supplies fresh water for external use.

The elegance of the approach lies in its thermodynamic bookkeeping. Alkaline water electrolysers typically convert only about 70 to 80 percent of their electrical input into the chemical energy of hydrogen, with the remainder appearing as heat. In conventional plants this heat is an inefficiency to be minimized. In the STHW architecture, it becomes an asset. Because low-temperature thermal desalination operates at modest temperatures and pressures, the electrolyser’s waste heat is sufficient to vaporize seawater and condense it as distillate. The researchers point out that the concept has surprisingly deep roots: a Swiss patent from 1928 already proposed generating distilled water in water electrolysis plants, but the idea never matured into an industrial demonstration—until now.

The team’s experimental campaign proceeded in two stages. First, a 20-kilowatt industrial pilot system ran for 100 consecutive days, producing 3.8 normal cubic meters of hydrogen per hour alongside 1.2 kilograms of fresh water per hour. That sustained, three-month trial is significant in a field where many seawater electrolysis claims rest on laboratory-scale electrodes tested for hours or days. Stability has historically been the Achilles heel of direct seawater electrolysis, in which chloride corrosion, competing chlorine chemistry, and precipitating magnesium and calcium hydroxides degrade catalysts and electrodes. By sidestepping direct seawater splitting altogether—distilling the water first, even if only within the same unit—the STHW process lets the electrolyser operate on effectively pure water, preserving the maturity and durability of conventional alkaline technology.

Scaling up, the researchers built a 250-kilowatt system that achieved 48 normal cubic meters of hydrogen per hour and 31.6 kilograms of fresh water per hour. Crucially, the integrated design delivered a 14.4 percent improvement in system electrical efficiency compared with running an alkaline electrolyser on fresh water alone. That gain comes from the dual dividend of waste heat recovery: the thermal energy recycled into distillation displaces electricity or fuel that a standalone desalination plant would otherwise consume, and the cogeneration of fresh water adds a sellable product without any additional primary energy input. In effect, the same electron entering the plant yields hydrogen, water, and a smaller thermal footprint than any of its competitors.

The engineering challenge was substantial. Integrating a thermal desalination stage with an industrial electrolyser required careful management of material flows, temperature gradients, and water balances. The team mapped the process feasibility and simplified the flowsheet so that seawater enters the distillation loop, vapor is condensed into product water, a portion is returned to the electrolysis stack, and brine is rejected—mirroring the mass flows of a compact combined heat-and-power plant, but with hydrogen and potable water as outputs. Figure-level analyses in the paper trace these material and energy streams, showing where heat exchangers recover the electrolyser’s reject heat and how the distillation unit maintains throughput across varying operating loads.

Direct seawater electrolysis, by contrast, has attracted enormous research attention in recent years, with notable demonstrations including a membrane-based seawater electrolyser published in Nature in 2022 and catalyst designs that adjust the local reaction environment to resist chloride attack. Yet a vocal segment of the electrochemistry community has questioned whether these approaches are economically meaningful, arguing in journals such as Joule and Energy and Environmental Science that hyping direct seawater splitting may actually hinder electrolyser development. The STHW results lend weight to that skepticism: instead of forcing electrolysis to endure the brutal chemistry of the ocean, the Dalian team’s process treats seawater as a resource to be purified, using free waste heat as the purification engine.

The economics appear to favor the coupled route decisively. A techno-economic analysis included in the study indicates that the STHW process is more profitable than the traditional tandem arrangement of desalination followed by electrolysis, in which a reverse-osmosis or electrodialysis plant is built, powered, and operated as a separate facility. The authors note that low-temperature thermal desalination avoids many of the membrane fouling, wetting, and scaling problems that plague membrane distillation, while the co-produced fresh water can offset local water demand—a valuable revenue stream or social benefit in arid coastal regions such as the Gulf states, where capital costs of desalination plants have long been a subject of intense study.

The implications ripple outward across the hydrogen economy. As countries draft national hydrogen strategies, water demand is emerging as a quiet constraint: the International Renewable Energy Agency has estimated that hydrogen production could require billions of cubic meters of water annually by mid-century, and analysts have urged the industry to mine nontraditional water sources rather than compete with agriculture and cities for freshwater. A 250-kilowatt demonstration is still far from the megawatt and gigawatt scales envisioned for export-oriented hydrogen hubs, but the architecture is inherently modular, built from two commercially proven unit operations—alkaline electrolysis and thermal distillation—rather than from experimental catalysts.

There remain engineering hurdles to confront on the path to commercialization. Long-term brine management, corrosion of distillation hardware, and the economics of waste-heat exchangers at larger scales will all require scrutiny, and the pilot results, while encouraging, cover a single 100-day campaign. Yet the demonstration marks a conceptual shift worth savoring: the same heat that engineers have spent decades trying to squeeze out of electrolysers has been recast as the driving force for a second product. In a world where 2.2 billion people lack safely managed drinking water and clean hydrogen remains stubbornly expensive, a machine that makes both from the sea—using energy that would otherwise warm the air—offers a rare and genuinely circular vision of the energy-water nexus.

Subject of Research: Coupled alkaline seawater electrolysis and low-temperature thermal desalination for co-production of hydrogen and fresh water

Article Title: A 250-kilowatt system for co-production of hydrogen and fresh water from seawater

Article References: Jiang, S., Zhu, P., Liu, Y., & Deng, D. (2026). A 250-kilowatt system for co-production of hydrogen and fresh water from seawater. Nature Energy. https://doi.org/10.1038/s41560-026-02130-6

Image Credits: AI Generated

DOI: 10.1038/s41560-026-02130-6

Keywords: hydrogen production, seawater electrolysis, desalination, alkaline water electrolysis, waste heat recovery, fresh water, Nature Energy, techno-economic analysis, green hydrogen, water-energy nexus, thermal distillation, industrial pilot system

The device, which the authors call a hydroxide exchange membrane carbon capture cell, or HEMCC, belongs to a growing family of electrochemical approaches to direct air capture. Unlike conventional solid sorbent systems that swing between hot and cold temperatures to grab and release CO2, electrochemical cells use renewable electricity to drive the capture chemistry, promising lower energy costs, modular scaling, and compatibility with intermittent power sources. The problem, the researchers note, is that few proposed electrochemical devices have simultaneously delivered low energy cost, high durability, and full purification of the captured CO2, and almost none have addressed the practical realities of scale-up and pressure drop that matter enormously when you are pushing enormous volumes of air through a machine.

The core of the new design is a pair of identical nickel hydroxide electrodes, the same kind of material that has served for decades as the positive electrode in nickel-metal hydride batteries. Nickel hydroxide cycles reversibly between Ni(OH)2 and nickel oxyhydroxide, NiOOH, in alkaline conditions, and it is this pH-swinging battery chemistry that the team exploits. When one electrode is discharged, it consumes hydroxide ions and acidifies its local environment, releasing CO2 from bicarbonate and carbonate; the opposite electrode charges and generates hydroxide, which converts CO2 in the incoming air into carbonate and bicarbonate, effectively capturing it. A hydroxide exchange membrane, an 80-micrometre-thick PiperION membrane supplied by Versogen, separates the two sides while allowing hydroxide ions to shuttle between them.

In operation, ambient air flows past the charging electrode, where its CO2 is stripped out and chemically bound, and the depleted air exits the cell. During the discharge half of the cycle, the roles reverse: the previously charged electrode now releases its stored CO2 as a concentrated stream that can be collected, purified, and sequestered or utilized. Because the cell is symmetric, with identical electrodes on either side of the membrane, the air feed and product collection lines simply switch sides each cycle, allowing continuous operation without any change in hardware. The team’s laboratory-scale device used 25-square-centimetre electrodes made by electrochemically precipitating nickel hydroxide onto nickel foam, a process in which the working electrode gained 0.83 grams of material while counter electrodes sacrificed nickel from a nickel chloride bath.

Before testing, the electrodes underwent a careful break-in protocol in 1 molar potassium hydroxide, cycling at low current densities to stabilize their capacity, which settled at roughly 2.1 to 2.4 milliampere-hours per square centimetre. Cyclic voltammetry revealed the key electrochemical signatures: an oxidation peak at 1.44 volts versus the reversible hydrogen electrode corresponding to the Ni(OH)2 to NiOOH conversion, a reduction peak at 1.28 volts for the reverse reaction, and the onset of parasitic oxygen evolution at 1.52 volts. That narrow window between the useful battery reaction and the wasteful oxygen evolution reaction is central to the cell’s efficiency, and at 2 milliamperes per square centimetre the kinetic overpotential for the battery reaction averaged just 0.09 volts.

The durability results are among the most striking in the study. The 25-square-centimetre laboratory cell ran for 5,000 hours, more than half a year of continuous operation, without catastrophic degradation, addressing one of the most persistent doubts about electrochemical capture devices, which often show rapid performance decay. Transient analysis of the cycling behaviour showed that electron efficiency, the fraction of electrical charge that goes into useful CO2 capture rather than side reactions, peaked at 0.32 during optimal portions of the cycle, with an average of 0.25, and that flux and efficiency were tightly coupled to the phase of the battery cycle. The researchers used these insights to design an operating strategy with dedicated capture and regeneration phases for each electrode.

Perhaps most importantly, the team did not stop at the laboratory bench. Working with RepAir DAC, they built a pilot-scale electrochemical stack of nine cells, each with 300 square centimetres of active area, and ran it for 48 hours. The stack achieved the same headline figures, 132 kilojoules per mole of CO2 and a flux of 0.19 moles of CO2 per square metre per hour, equivalent to 75 kilograms of CO2 captured per square metre per year, while meeting the demanding 300-pascal pressure drop requirement that direct air capture systems must satisfy to keep fan energy manageable. Pressure drop is a frequently ignored constraint in academic capture studies, yet it can dominate the total energy budget of a real-world plant handling vast volumes of air, so demonstrating compliance at pilot scale is a significant step toward commercial credibility.

On the strength of these results, the authors present a techno-economic pathway to capturing CO2 for less than 100 US dollars per tonne, a threshold widely regarded as the price point at which direct air capture becomes viable at climate-relevant scale. Their projection rests on energy technology learning rates, the well-documented tendency of manufacturing costs for electrochemical and energy hardware to fall steadily as production volumes grow, a pattern seen in solar panels, lithium-ion batteries, and fuel cells. Because the HEMCC borrows mature manufacturing concepts from batteries and fuel cells, including membrane electrode assemblies and porous electrode architectures grounded in decades of theory dating back to Newman’s classic analyses, the researchers argue that its cost trajectory could follow those successful technologies rather than the steeper curves typical of bespoke chemical plants.

The work was supported by the US Department of Energy’s National Energy Technology Laboratory and the US Department of Defense Army Research Laboratory, and it arrives at a moment when governments and companies are racing to build gigatonne-scale carbon removal capacity. The Intergovernmental Panel on Climate Change and the International Energy Agency both count direct air capture among the tools likely needed to reach net-zero emissions by mid-century, particularly for offsetting hard-to-abate sectors such as aviation and agriculture. If the Delaware and RepAir teams’ durability and cost projections hold up as the technology scales beyond the pilot stage, the humble nickel hydroxide electrode, a workhorse of twentieth-century batteries, may find itself pressed into service as a cornerstone of twenty-first-century climate repair, quietly scrubbing the sky one reversible charge cycle at a time.

Subject of Research: A nickel hydroxide symmetric battery cell with a hydroxide exchange membrane for electrochemical direct air capture of carbon dioxide.

Article Title: A Ni(OH)2 symmetric battery cell for hydroxide exchange membrane-based direct air capture of CO2

Article References: Buchen, J. R., Wang, T., Geiger, B. K., Gluz, N. Y., Artoul, M., Hiegel, J.-P., Achrai, B., Setzler, B. P., & Yan, Y. (2026). A Ni(OH)2 symmetric battery cell for hydroxide exchange membrane-based direct air capture of CO2. Nature Energy. https://doi.org/10.1038/s41560-026-02129-z

Image Credits: AI Generated

DOI: 10.1038/s41560-026-02129-z

Keywords: direct air capture, carbon dioxide removal, nickel hydroxide, hydroxide exchange membrane, electrochemical carbon capture, battery cell, climate change, Nature Energy, energy cost, carbon capture and storage, electrochemistry, pilot-scale stack

Pipelines are widely viewed as the cheapest option for transporting large volumes of hydrogen over land, especially when compared with trucking compressed gas or converting hydrogen into ammonia and back again. Most large-scale modeling exercises, however, draw on generic cost curves, frequently derived from natural gas pipeline data and adjusted upward by a fixed factor to account for hydrogen’s unique material challenges. The new analysis shows that such averages can obscure differences of a factor of two or more between regions, differences large enough to change which hydrogen supply chains make economic sense in a given country.

At the heart of the study is a decomposition of pipeline costs into their physical and institutional components. On the physical side, terrain matters enormously. Building a pipeline through mountainous regions requires tunneling, aerial crossings, and extensive slope stabilization, all of which inflate capital expenditure per kilometer. Urban corridors demand costly routing around dense settlements, deeper burial depths, and additional safety clearances because hydrogen’s wide flammability range and low ignition energy raise concerns that regulators treat more conservatively than those for natural gas. Crossing rivers, canals, railways, and highways adds specialized engineering at every interruption, and in some regions the sheer density of such obstacles multiplies unit costs well above the levels assumed in global models.

Geology and climate add further layers of variation. Corrosive soils and high water tables accelerate degradation of steel and require more robust coatings and cathodic protection systems. Seismic zones demand flexible joints and reinforced design standards. In permafrost or areas with extreme seasonal temperature swings, ground movement can stress welds and valves, prompting thicker-walled pipe and more frequent inspection regimes. None of these factors is exotic; each is routine in pipeline engineering. Yet because hydrogen-specific datasets are sparse, modelers have historically lacked the regional resolution to capture them, leading to systematic underestimates of cost in precisely the regions, often in the Global South and in geologically challenging terrains, where cheap renewable electricity might otherwise make hydrogen production most attractive.

The political dimension of the analysis is arguably its most novel contribution. The cost of a pipeline is not determined by steel and labor alone but by the institutional environment in which it is built. Permitting timelines differ by orders of magnitude across jurisdictions: in some European countries, a new transmission pipeline can spend a decade in environmental review, judicial challenge, and multi-agency consultation, while in others, streamlined approval regimes allow construction to begin within a couple of years. Each year of delay carries a real financial cost through financing charges, inflation, and deferred revenue, and the researchers show that these time-related costs can rival or exceed the physical construction cost premium of difficult terrain.

Regulatory frameworks also shape costs directly. Standards governing pipeline design, operating pressure, odorization requirements, and proximity to buildings vary widely, and some jurisdictions have not yet finalized hydrogen-specific codes at all, creating uncertainty that deters investment and raises the cost of capital. Rights-of-way acquisition depends on land ownership structures and compensation norms; in countries with fragmented landholdings or strong customary land rights, negotiating a continuous corridor can be slow and expensive. Tariff regulation matters too, because the business case for a hydrogen pipeline typically rests on guaranteed long-term throughput, and the degree to which regulators allow capacity risk to be socialized across users, or borne by the pipeline owner, changes the required rate of return and therefore the delivered cost of hydrogen.

By combining geographic information system data on terrain, land use, population density, and water bodies with country-level indicators of permitting duration, regulatory maturity, and political stability, the researchers construct regionally differentiated cost estimates that reveal a strikingly uneven global picture. Coastal industrial clusters in some regions emerge as far cheaper to connect than generic models predict, while landlocked renewable-rich areas, often touted as future hydrogen export powerhouses, face pipeline costs that erode a substantial share of their production advantage. The findings suggest that the geography of future hydrogen trade may be determined as much by corridors, codes, and courts as by the price of electrolyzers and renewable electricity.

Repurposing existing natural gas pipelines, frequently cited as a way to slash hydrogen transport costs by well over half, also receives a more nuanced treatment. The study emphasizes that reuse is not uniformly feasible: older pipelines built before modern integrity standards, those made of materials vulnerable to hydrogen embrittlement, and those traversing areas where hydrogen blending rules remain unsettled may require extensive assessment, repair, and upgrading before conversion. The economics of repurposing therefore inherit the same regional sensitivities as new construction, and blanket assumptions that existing networks can absorb hydrogen cheaply could misdirect both policy support and private investment.

For policymakers, the implications are concrete. Reducing permitting timelines and providing legal clarity on hydrogen pipeline regulation can deliver cost reductions comparable to years of anticipated technology learning, and doing so costs governments far less than subsidizing hardware. Coordinated corridor planning, early community engagement, and harmonized cross-border standards for interconnected networks are identified as high-leverage interventions. For modelers and investors, the message is that region-specific cost inputs should become standard practice, since the difference between a viable and a marginal hydrogen project may lie less in the electrolyzer stack than in the ground it crosses and the institutions that govern it.

As governments finalize billions of dollars in hydrogen infrastructure funding, the study offers a timely corrective to optimism grounded in global averages. The hydrogen economy of the coming decades will be built pipe by pipe, permit by permit, and country by country, and its true cost will be written not in spreadsheet defaults but in mountains, soil, courts, and regulatory codes. Recognizing that heterogeneity, the authors argue, is the first step toward infrastructure planning that is both financially realistic and strategically sound.

Subject of Research: Regional geographical and political determinants of hydrogen pipeline costs

Article Title: Exploring hydrogen pipeline costs by considering regional geographical and political characteristics

Article References: Weißenburger, B., Karkossa, L., Stephan, A., & McKenna, R. (2026). Exploring hydrogen pipeline costs by considering regional geographical and political characteristics. Nature Energy. https://doi.org/10.1038/s41560-026-02141-3

Image Credits: AI Generated

DOI: 10.1038/s41560-026-02141-3

Keywords: hydrogen, pipelines, hydrogen economy, infrastructure costs, permitting, energy transition, regulatory frameworks, pipeline repurposing, geography, energy policy, Nature Energy, decarbonization

The significance of the demonstration lies in its scale and integration. Laboratory reports of seawater electrolysis appear regularly, but few technologies have graduated beyond the bench. A 250 kW system is a meaningful industrial pilot size, large enough to expose engineering realities such as heat management, brine handling, corrosion and long-term stability that small laboratory cells simply never encounter. By designing the distillation and electrolysis stages as one thermally and hydraulically linked unit rather than two separately optimized plants, the researchers eliminated much of the parasitic energy burden and capital cost that normally separate seawater from the ultrapure water that conventional electrolyzers demand.

The underlying problem is well known to electrochemists. Alkaline water electrolyzers, among the most mature and durable electrolysis technologies, circulate a concentrated potassium hydroxide electrolyte and split water at nickel-based electrodes. They are robust against many impurities, yet the magnesium, sulfate and, above all, chloride ions in seawater wreak havoc. Chloride ions that reach the anode can participate in chlorine and hypochlorite evolution reactions that compete with oxygen evolution, corroding electrodes and membranes and contaminating the product gas. Precipitates of magnesium hydroxide and calcium carbonate can clog porous transport layers and poison catalyst surfaces. This is why virtually every commercial electrolysis installation relies on deionized water, often to resistivity specifications measured in megohm-centimeters.

Previous attempts to sidestep this requirement have taken two broad routes. One is direct seawater electrolysis, in which specially designed catalysts and membranes resist chloride chemistry; a prominent 2023 Nature Energy study demonstrated a self-driven system that suppressed chloride corrosion through in situ generated protective layers, and a 2026 follow-up by Jiang and colleagues advanced that line of work. The other route is upstream desalination, in which seawater is purified by reverse osmosis, membrane distillation or thermal processes before entering a standard electrolyzer. Each route carries penalties: direct seawater electrolysis remains constrained by catalyst durability and selectivity at industrially relevant current densities, while standalone desalination adds cost, complexity and energy demand that hydrogen producers have been reluctant to absorb.

The unified system described in the new report belongs to the second family but reframes its economics entirely. Vacuum distillation lowers the boiling point of water by reducing pressure, allowing evaporation at temperatures far below 100 degrees Celsius. Alkaline electrolysis stacks operate with substantial inefficiency: a portion of the electrical input inevitably degrades into heat at operating temperatures typically between 60 and 90 degrees Celsius. In conventional plants this heat is a nuisance, requiring cooling water and radiating away as waste. In the unified design, that same low-grade waste heat becomes the driving force for vacuum distillation of seawater. The electrolyzer effectively pre-heats and purifies its own feedwater, closing the loop between the two processes.

This thermal coupling yields several compounding benefits. The distillation step produces water of a purity suitable for direct injection into the alkaline electrolyte circulation loop, so the plant draws seawater rather than municipal fresh water, neutralizing objections from communities and regulators in water-stressed coastal regions. The concentrated brine byproduct can be managed as a manageable waste stream, and in principle carries value as a feedstock for salt and mineral recovery. Because no external steam boiler or electrically driven desalination train is required, the overall energy efficiency of hydrogen production improves relative to a conventional arrangement of separate desalination and electrolysis plants, and the system’s footprint shrinks accordingly.

The 250 kW demonstration matters because it interrogates the integration at a scale where heat balances become genuine engineering constraints rather than laboratory conveniences. At this size, the researchers could quantify how much of the stack’s waste heat is recoverable, how the vacuum distillation unit responds to the transient thermal profile of a real electrolyzer under variable renewable power, and how water quality, brine concentration and hydrogen output behave over sustained operation. Co-producing fresh water alongside hydrogen also opens a second revenue stream: a coastal hydrogen plant can double as a small desalination facility, supplying potable or industrial water to its host community and improving the project’s overall economics in ways that hydrogen sales alone cannot.

Analysts following the hydrogen sector have repeatedly emphasized that water availability is an underappreciated constraint on global electrolyzer deployment. The International Energy Agency’s Global Hydrogen Review has documented the rapid growth of announced electrolyzer capacity, much of it concentrated in coastal and arid regions such as Australia, the Middle East, Chile and North Africa, precisely where solar and wind resources are strongest and fresh water is scarcest. Policy frameworks, including those developed by Australian state agencies to manage water resources during extreme events, increasingly scrutinize industrial water withdrawals. A technology that converts seawater into both a clean fuel and fresh water directly addresses the resource conflict at the heart of the green hydrogen build-out.

Challenges remain before such unified plants can be considered commodity technology. Long-term materials compatibility is paramount: vacuum distillation vessels, heat exchangers and condensers must resist corrosion and scaling over thousands of hours, and the electrolyzer stack must tolerate the trace impurities that survive even high-quality distillation. Maintaining vacuum conditions adds mechanical complexity and pumping loads that must be optimized against the heat available from the stack. The economics will also hinge on the value assigned to the co-produced fresh water, which varies enormously by geography. Nevertheless, the demonstration that waste heat from alkaline electrolysis can drive vacuum distillation of seawater at the quarter-megawatt scale offers a credible, thermodynamically elegant answer to one of the hydrogen economy’s most persistent bottlenecks, and points the way toward hydrogen production that quenches water scarcity rather than deepening it.

Subject of Research: A unified system coupling alkaline water electrolysis with vacuum distillation to co-produce hydrogen and fresh water from seawater

Article Title: A unified distillation and electrolysis system

Article References: Love, J. G. (2026). A unified distillation and electrolysis system. Nature Energy. https://doi.org/10.1038/s41560-026-02136-0

Image Credits: AI Generated

DOI: 10.1038/s41560-026-02136-0

Keywords: green hydrogen, seawater electrolysis, vacuum distillation, alkaline water electrolysis, desalination, waste heat recovery, hydrogen economy, water scarcity, electrocatalysis, renewable energy, Nature Energy, co-production

The core of the innovation lies in the elastocaloric effect itself. When a shape memory material such as a nickel-titanium alloy is mechanically stressed, it undergoes a reversible phase transformation from austenite to martensite. This transformation is endothermic in one direction and exothermic in the other: stretching or compressing the material forces the crystal structure to rearrange, absorbing heat from the surroundings, while releasing the stress causes the structure to revert, releasing heat elsewhere. In principle, this cycle can pump heat with no refrigerant gases at all, sidestepping the hydrofluorocarbons responsible for substantial greenhouse gas emissions. Because the working body is a solid metal film, the concept promises compact, leak-free, and environmentally benign cooling devices.

Until recently, however, elastocaloric systems faced a fundamental obstacle: the mechanical work needed to drive the phase transformation must be supplied by electric motors, actuators or other powered mechanisms, which erodes the efficiency gains and keeps the devices tethered to the grid. The new work elegantly removes this dependency. The team’s architecture couples two distinct shape memory film components in a single system. The first acts as a thermal engine, exploiting the one-way shape memory effect: when heated by a low-grade source, it contracts and generates mechanical force. That force is mechanically transmitted to a second shape memory element, the elastocaloric refrigerant, which is thereby cyclically loaded and unloaded. The loading stage absorbs heat from the cold side of the device; the unloading stage rejects it to the hot side, completing a refrigerator cycle driven purely by heat at the input.

The use of thin films rather than bulk alloys is a deliberate and consequential design choice. In bulk shape memory elements, the large cross-sections required to generate useful cooling power also create steep thermal and mechanical gradients, limiting cycling frequency and accelerating fatigue. Thin films, by contrast, can be cycled rapidly because heat penetrates their tiny thickness almost instantly, and the stresses involved in martensitic transformation are better tolerated at small dimensions. The researchers fabricated film-based elements that undergo superelastic cycles at high frequency, enabling the continuous, rhythmic exchange of heat that a practical refrigerator demands. Film geometry also allows thousands of elements to be patterned and operated in parallel, a route to scaling cooling capacity without redesigning the underlying physics.

The concept of heat-driven elastocaloric cooling was not born overnight. A 2019 theoretical study by Shan Qian and colleagues at the University of Maryland laid out the design principle and numerical simulation of a heat-driven system based on regenerative compression, showing in silico that the idea could in principle be thermodynamically competitive. Subsequent reviews catalogued the promise of film-based elastocaloric devices, noting their high power density and mechanical simplicity. In parallel, experimental groups worldwide pushed elastocaloric cooling toward practical power levels; in 2025, a team led by Gengqiang Zhou reported a multi-cell architecture achieving kilowatt-scale cooling power, a landmark that proved the technology could compete with conventional compressors in raw capacity. The new demonstration ties these threads together, converting that accumulated expertise into a system that runs on heat rather than electricity.

The thermodynamics of the device reward careful attention. The thermal engine element operates between a hot reservoir, supplied by the low-grade heat source, and a rejection temperature, extracting work as the shape memory film contracts through its transformation range. Because low-grade heat is thermodynamically dilute, the conversion efficiency of this stage is inherently modest, but the essential point is that the input energy is heat that would otherwise be discarded. The elastocaloric stage, meanwhile, can achieve high coefficients of performance because the mechanical work applied is almost entirely recovered during unloading; superelastic shape memory alloys dissipate only a small fraction of the input work per cycle as hysteresis. In the coupled system, therefore, the net electrical input required to run the cycle can approach zero, with small amounts needed only for control, valves and heat-transfer auxiliaries.

Materials science challenges remain at the heart of making such systems durable. Shape memory alloys are subject to functional fatigue: after many thousands of superelastic cycles, their transformation characteristics degrade, the temperature hysteresis widens, and cooling performance drifts. The researchers addressed this through film composition and microstructure optimization, exploiting the superior fatigue resistance that thin-film sputtered nickel-titanium can offer when grain size and texture are controlled. Thermal design was equally critical. Because the engine and refrigerant films operate at different temperatures, the system must shuttle heat efficiently between stages, and the team’s regenerative arrangement recovers heat within the cycle rather than venting it, boosting the overall temperature lift the device can sustain from a given quality of input heat.

The practical implications are considerable. Enormous quantities of low-grade heat, below roughly 150 degrees Celsius, are released every day by power plants, data centers, factories, refrigeration condensers, and vehicle engines, and nearly all of it is simply rejected to the atmosphere. A cooling technology that can convert this stranded resource into useful refrigeration, with minimal electricity, would upend the energy economics of cold chains, building climate control, and electronics thermal management. In remote or off-grid settings, solar thermal collectors could supply the driving heat directly, creating cooling systems entirely independent of electrical infrastructure. For electric vehicles, where every watt drawn from the battery reduces range, a heat-driven elastocaloric air conditioner could tap engine and power-electronics waste heat instead.

The environmental stakes add urgency. Hydrofluorocarbon refrigerants, while ozone-safe, are potent greenhouse gases thousands of times more effective at trapping heat than carbon dioxide, and international agreements are phasing them down. Vapor-compression systems are also responsible for a substantial fraction of global electricity demand, a share that rises as the planet warms and cooling needs multiply. Solid-state elastocaloric cooling eliminates the refrigerant entirely and, in the heat-driven configuration described here, can largely eliminate the electricity demand as well. If scaled successfully, the technology attacks both halves of the cooling problem at once.

Considerable engineering hurdles still separate the laboratory demonstration from commercial products. Cooling power densities must be maintained over millions of cycles, heat exchangers must be integrated without negating the system’s compactness, and the mechanical linkages coupling the engine and refrigerant films must survive continuous high-frequency operation. Nevertheless, the trajectory of the field is unmistakable: from theoretical proposals five years ago, to kilowatt-scale demonstrations, and now to a heat-driven architecture that dissolves the technology’s biggest structural weakness. What has been demonstrated is a proof of principle with genuinely disruptive potential, a refrigerator whose primary fuel is heat that the world already produces and squanders. As the researchers and their peers refine the materials and architectures, elastocaloric cooling may move from the pages of journals into the machinery of everyday life, driven not by the grid but by the warmth we throw away.

Subject of Research: Heat-driven elastocaloric cooling using shape memory alloy films

Article Title: A heat-driven route to elastocaloric cooling

Article References: A heat-driven route to elastocaloric cooling. (n.d.). https://doi.org/10.1038/s41560-026-02128-0

Image Credits: AI Generated

DOI: 10.1038/s41560-026-02128-0

Keywords: elastocaloric cooling, shape memory alloys, nickel-titanium films, solid-state refrigeration, low-grade waste heat, martensitic phase transformation, thermal engine, functional fatigue, cooling energy efficiency, refrigerant-free cooling, Nature Energy, thermal management

The commentary accompanies two independent studies that, taken together, reveal a previously underappreciated failure mode: self-discharge driven by residual electronic conductivity in solid electrolytes. Self-discharge is familiar to anyone who has picked up a gadget after months of storage only to find the battery partially drained. In conventional liquid-electrolyte cells, self-discharge arises from parasitic side reactions and impurity-driven shuttles. In solid-state cells, the story turns out to be more subtle. Because the electrolyte is a solid, the cell can be fully assembled and sealed, and yet an internal electronic pathway can still allow charge to bleed from one electrode to the other without any external connection at all.

Physically, the mechanism can be understood as an internal short circuit of very high resistance. A solid electrolyte is never a perfect electronic insulator; its electronic conductivity, while many orders of magnitude lower than its ionic conductivity, is finite. When a cell is charged, the two electrodes sit at different electrochemical potentials, separated by the full cell voltage. That potential difference drives a minute electronic current through the electrolyte even at open circuit, slowly transferring electrons and, through coupled chemical processes, neutralizing the stored lithium gradient between the cathode and the anode. Individually the leakage currents are vanishingly small, but battery storage is a marathon measured in months and years, and even minuscule currents accumulate into meaningful capacity loss over a product’s shelf life.

The two studies highlighted in the commentary converge on this conclusion from complementary directions, and both emphasize that the problem becomes more severe as cells become thinner and more practical. Laboratory demonstration cells often use thick, mechanically robust solid electrolyte layers, which present a long, high-resistance path to stray electrons. Real commercial designs, however, demand thin electrolyte membranes to maximize volumetric and gravimetric energy density. Halving the electrolyte thickness doubles the electronic leak for a given cell voltage, meaning that the very design changes needed to make solid-state batteries commercially competitive also amplify the hidden leak. The studies identify the conductivity limits that solid electrolytes must satisfy to guarantee long shelf life, effectively setting an engineering specification that materials designers can now target explicitly.

This framing represents a shift in how the field thinks about solid electrolyte characterization. Historically, researchers have compared candidate materials almost exclusively by their ionic conductivities, chasing sulfides, oxides and halides that transport lithium ions as fast as possible. Values exceeding ten millisiemens per centimeter, rivaling or exceeding liquid electrolytes, are now routinely reported. Electronic conductivity, by contrast, has often been measured only sporadically, and sometimes under conditions that do not reflect the electrochemical potentials a real cell experiences. The new work makes clear that the ratio of electronic to ionic transport is not a curiosity but a first-order design parameter, and that a material with spectacular ionic conductivity can still fail the shelf-life test if its electronic leakage is too high.

The commentary’s authors situate these findings within a broader body of literature on electronic transport in solid electrolytes. Prior theoretical and computational studies had already established that many widely used solid electrolytes, including thiophosphate-based materials, possess non-negligible electronic conductivity, and that redox-active elements within their crystal structures can mediate electronic conduction. Experimental reports had also documented oxidative decomposition at cathode interfaces and the formation of electronically conductive interphases. What the two new studies add is the direct connection between this background knowledge and a measurable, practically consequential phenomenon: capacity loss at open circuit in assembled cells, quantified against electrolyte thickness, voltage and storage time.

The practical implications reach into nearly every corner of the solid-state battery program. For cell engineers, the results suggest that shelf-life specifications cannot be met by sealing and thermal management alone; the intrinsic electronic conductivity of the electrolyte layer must be engineered below a critical threshold that scales with allowable storage duration. For materials scientists, the findings add an optimization target that may sometimes conflict with existing goals, since processing routes that densify electrolyte membranes or improve interfacial contact could also alter their defect chemistry and electronic transport. For theorists, the work underscores the value of first-principles predictions of electronic band structure, defect ionization and polaron hopping in complex solid electrolytes, which can guide screening before samples are ever synthesized.

There is also a diagnostic dimension. Because self-discharge through electronic leakage leaves distinctive signatures, such as voltage decay profiles at open circuit that depend systematically on electrolyte thickness and temperature, the phenomenon offers an accessible experimental probe. Testing protocols that deliberately vary membrane thickness can separate electronic leakage from other degradation pathways, such as interfacial decomposition or dendrite formation, giving the community a cleaner way to attribute capacity loss to its root cause. In an industry where a single misdiagnosed failure mode can misdirect years of development, such discriminating tests carry real value.

None of this diminishes the fundamental appeal of solid-state batteries, and the commentary is careful to frame the new results as a design constraint rather than a fatal flaw. The ionic conductivities of the best solid electrolytes are extraordinary, the interface chemistry is increasingly well controlled, and manufacturing routes for thin membranes are maturing rapidly. What the findings change is the checklist. A viable solid electrolyte must now demonstrate not only fast lithium transport and electrochemical stability but also electronic insulation sufficient to keep a charged cell from slowly draining itself while it sits in a warehouse waiting to be installed in a vehicle.

The image of a solid that leaks like a sieve, only for electrons rather than for ions, is likely to resonate well beyond the battery community, because it illustrates a recurring theme in materials science: properties that are negligible at one scale or one timescale can dominate at another. As solid-state cells move from laboratory prototypes toward commercial products with multi-year warranties and grid-scale storage duties, the hidden leak identified in these studies will need to be plugged, measured and monitored with the same rigor that the field has long applied to ionic conduction. The two studies and the accompanying commentary give researchers the conceptual tools and the quantitative limits to do exactly that, turning a subtle electrochemical surprise into an actionable engineering target.

Subject of Research: Self-discharge in solid-state batteries caused by residual electronic conductivity of solid electrolytes

Article Title: A hidden leak in solids

Article References: Noh, J., & Kang, K. (2026). A hidden leak in solids. Nature Energy. https://doi.org/10.1038/s41560-026-02133-3

Image Credits: AI Generated

DOI: 10.1038/s41560-026-02133-3

Keywords: solid-state batteries, solid electrolytes, self-discharge, electronic conductivity, ionic conductivity, shelf life, lithium-ion transport, energy storage, battery degradation, Nature Energy, hidden, leak

The heart of the advance is a battery built around disulfur dichloride, S2Cl2, a sulfur-containing compound in which sulfur sits at a higher oxidation state than the elemental sulfur used in traditional lithium–sulfur cells. Rather than cycling sulfur between its elemental form and lithium sulfide through the conventional two-electron pathway, the new chemistry reversibly converts lithium sulfide, Li2S, back into disulfur dichloride through a three-electron sulfur redox process. That extra electron transfer per sulfur atom is the key to unlocking both a higher cell voltage and a greater storage capacity, since the total energy a battery delivers is the product of its voltage and the charge it can move.

The numbers reported by the team are striking. At room temperature, 25 degrees Celsius, and a moderate discharge rate of 0.2C, the average operating voltage of the cell rises from approximately 2.05 volts in a conventional lithium–sulfur configuration to 2.54 volts. The sulfur-specific capacity increases by 58 percent relative to standard sulfur chemistry. Taken together, these gains translate into an electrode-level specific energy exceeding 1,700 watt-hours per kilogram, a figure far beyond what today’s commercial cathodes can achieve, and the cells sustain this performance over more than 100 charge–discharge cycles.

Achieving reversible high-valence sulfur chemistry has proven notoriously difficult in the past, and the reasons illuminate why this result matters. When chemists have attempted to push sulfur into higher oxidation states using halogens such as chlorine, two obstacles have consistently emerged. First, chloride species in typical electrolytes bind strongly to lithium ions, tying up the charge carriers needed for the battery to function. Second, halogen-mediated reactions tend to consume the electrolyte itself, degrading the cell from the inside out and destroying reversibility over repeated cycles. The new work demonstrates that both problems can be overcome with a carefully designed liquid medium.

The enabling technology is a free-chloride-rich ionic liquid electrolyte, a class of molten salts that remain liquid at or near room temperature and consist entirely of ions. Unlike conventional solvent-based electrolytes, this ionic liquid keeps chloride anions in an unbound, or free, state rather than locking them to lithium cations. In this configuration, the electrolyte does far more than simply conduct ions between the electrodes. It functions as an ionic mediator, actively participating in the redox chemistry that shuttles sulfur between its low-valence and high-valence states, while contributing only a minor share of the measured capacity itself.

The researchers support their electrochemical measurements with an extensive suite of characterization techniques, including synchrotron X-ray absorption spectroscopy performed at beamline 8-BM of the National Synchrotron Light Source II at Brookhaven National Laboratory, X-ray photoelectron spectroscopy, in situ Raman spectroscopy and galvanostatic intermittent titration. Molecular dynamics simulations, conducted with custom force field parameters and code that the team has released openly on Zenodo, provide atomistic insight into how the phase-separated ionic-liquid structure stabilizes the chloride-mediated reaction pathway. Together, these tools confirm that the conversion between lithium sulfide and disulfur dichloride is genuinely reversible across repeated cycles.

The implications for energy storage are considerable. Lithium–sulfur batteries are attractive not only for their theoretical energy density but also for their supply chain: sulfur is a byproduct of petroleum refining and is available in quantities that dwarf the demand of any conceivable battery market. Raising the operating voltage by nearly half a volt may seem like a modest increment, but because energy scales directly with voltage, this single improvement multiplies the practical energy output of every gram of active material in the cell. Combined with the capacity boost from three-electron redox, the approach could move lithium–sulfur technology from a laboratory curiosity toward a genuine competitor for electric vehicles, grid storage and aerospace applications.

The research also reframes how battery scientists think about electrolytes. For most of the history of electrochemistry, the electrolyte has been treated as a passive component, chosen primarily for its stability and ionic conductivity. Here, the electrolyte is an active chemical participant, engineered with precision so that its chloride content mediates sulfur oxidation without parasitic consumption. This concept of an electrolyte that serves as a reaction mediator while remaining substantially intact echoes strategies explored in other emerging chemistries, including lithium–chlorine, lithium–sulfur dioxide and lithium–sulfur hexafluoride systems, but the authors show that their formulation achieves a rare combination of high voltage, high capacity and sustained reversibility.

Significant engineering challenges remain before cells of this type could leave the laboratory. The performance was demonstrated at the electrode level rather than in fully optimized pouch or cylindrical formats, and scaling ionic-liquid electrolytes to mass production will require attention to cost, viscosity and low-temperature behavior. Nevertheless, the demonstration of more than 100 stable cycles at an electrode-level specific energy above 1,700 watt-hours per kilogram establishes a new benchmark for sulfur-based batteries and offers the field a compelling proof of concept: that pushing sulfur to higher oxidation states, long considered a dead end because of irreversible halogen side reactions, can be made practical when the electrolyte is designed as an ally rather than a bystander.

As the global demand for high-energy, low-cost batteries intensifies, breakthroughs of this kind underscore how much untapped potential remains in some of chemistry’s most abundant elements. By coaxing a single sulfur atom to give up or take on three electrons instead of two, and by recruiting chloride ions as willing chemical partners rather than destructive interlopers, the University of Maryland-led team has shown that even the oldest rival to lithium-ion technology still holds surprises. The work was funded in part by the US Department of Energy’s Basic Energy Sciences program and its Vehicle Technologies Office, and the authors report no competing financial interests.

Subject of Research: Chloride-mediated three-electron sulfur redox chemistry in rechargeable lithium–disulfur dichloride batteries using a free-chloride-rich ionic liquid electrolyte

Article Title: Lithium–disulfur dichloride batteries

Article References: Zhang, N., Zhang, J., Zhang, W., Wang, Z., Zhao, C.-X., Li, A.-M., Liu, Y., Xia, K., Mesirow, C., Yang, Y., Lucht, B. L., Hu, E., Ji, X., Jiang, D.-E., Xu, J., & Wang, C. (2026). Lithium–disulfur dichloride batteries. Nature Energy. https://doi.org/10.1038/s41560-026-02120-8

Image Credits: AI Generated

DOI: 10.1038/s41560-026-02120-8

Keywords: lithium-sulfur batteries, disulfur dichloride, ionic liquid electrolyte, sulfur redox chemistry, energy density, chloride mediator, lithium sulfide, high-voltage batteries, electrolyte design, polysulfide shuttling, rechargeable batteries, Nature Energy

The core of the advance is a chemical transformation that converts elemental sulfur into disulfur dichloride, a compound in which each sulfur atom sits in the S+1 oxidation state. That may sound like a small bookkeeping change, but in electrochemistry the oxidation state of the active material is everything. The energy a battery delivers per electron is set by the voltage at which the conversion reaction occurs, and that voltage is in turn dictated by the thermodynamics of the chemical species involved. Elemental sulfur cycles between S0 and S-2 during ordinary discharge, a two-electron-per-atom process that tops out at roughly 2.1 to 2.2 volts against lithium. By accessing the S+1 state, the new approach shifts the reaction landscape to a much more favorable potential, delivering a higher cell voltage and therefore more usable energy from every electron exchanged.

The significance of the S+1 state goes beyond raw voltage. In conventional lithium-sulfur cells, the discharge pathway proceeds through a sequence of soluble lithium polysulfide intermediates, chains of sulfur atoms of varying length that dissolve into the electrolyte and migrate between the electrodes. This polysulfide shuttling is the notorious culprit behind the chemistry’s poor cycling stability: dissolved intermediates drift to the lithium anode, react parasitically, thicken interfaces with insulating byproducts, and are never fully returned to the cathode. Active material is progressively lost, the electrolyte is consumed, and the cell fades. A chemistry anchored in disulfur dichloride changes the intermediates themselves, and with them the entire degradation cascade that has plagued the field since its inception.

The News & Views analysis places this development in the long arc of sulfur battery research, a lineage stretching back to foundational reviews of lithium battery chemistry and to the early 2000s work on ordered carbon-sulfur cathodes that first showed how nanostructured hosts could tame polysulfide loss. Over the intervening years, researchers have pursued nearly every conceivable fix: porous carbon scaffolds to physically trap polysulfides, catalytic surfaces to accelerate their conversion, electrolyte formulations to suppress their solubility, and interlayer membranes to intercept them mid-migration. Each strategy delivered incremental gains, but none altered the fundamental thermodynamic ceiling of the S0 to S-2 couple. The halogen-assisted route is different in kind, not merely in degree, because it rewrites the reaction itself rather than managing its side effects.

Chlorine, the halogen at the heart of the new chemistry, is not an obvious hero for battery designers. It is corrosive, reactive, and demanding in terms of materials compatibility. Yet the analysis underscores that careful system-level engineering, matching the electrolyte, the electrode architecture, and the operating protocol to the demands of the sulfur-chlorine chemistry, makes the transformation to disulfur dichloride both controllable and reversible. The selection process for the reaction pathway, illustrated schematically in the accompanying analysis, shows how the choice of halogenated environment determines whether sulfur follows the classical polysulfide route or is diverted into the higher-oxidation-state compound. That selectivity is the engineering achievement: the cell is not merely tolerating chlorine, it is exploiting it as an active participant in the energy-storage reaction.

The practical consequences are twofold. First, the higher operating voltage translates directly into higher energy density, because energy is the product of voltage and capacity. A lithium-sulfur cell that operates meaningfully above the traditional 2.1-volt plateau closes part of the voltage gap with lithium-ion chemistry while retaining sulfur’s overwhelming advantage in theoretical capacity. Second, and arguably more important for commercialization, the improved cycling stability addresses the failure mode that has kept lithium-sulfur cells out of electric vehicles and grid storage despite their tantalizing specifications. A battery that holds its voltage and its capacity over hundreds of cycles changes the economic calculus entirely, since lifetime, not headline energy density, is what determines cost per kilowatt-hour delivered over a system’s service life.

The analysis also situates the work within a broader sustainability conversation. Sulfur is a byproduct of petroleum refining, available in quantities that dwarf any plausible battery demand, and it is free of the cobalt, nickel, and lithium-supply anxieties that shadow conventional cathode supply chains. Earlier work on sustainable battery chemistries has emphasized that the next generation of energy storage must be judged not only on performance but on material abundance, cost, and environmental footprint. A sulfur cathode chemistry that finally delivers competitive voltage and longevity would check every one of those boxes, which is why the halogen-assisted approach has drawn attention well beyond the electrochemistry community.

Challenges remain, and the analysis is candid about them. Working with chlorine-containing species imposes stringent requirements on cell sealing, electrode passivation, and electrolyte stability, and any commercial design must demonstrate that these can be met at scale and at cost. The long-term behavior of the disulfur dichloride chemistry under the thousands of cycles demanded of grid and automotive batteries has yet to be established, and the safety case for a chlorine-participating cell chemistry will need to be made with the same rigor applied to any new battery platform. There is also the question of how the lithium anode, itself a source of instability in every lithium-metal system, behaves in the new chemical environment. These are the questions that will decide whether the laboratory advance becomes a product.

What makes the moment notable is the shift in strategy it represents. For two decades, lithium-sulfur research has largely been a campaign of containment, confining, catalyzing, and intercepting the intermediates of a reaction whose fundamental thermodynamics were accepted as fixed. The halogen-assisted oxidation route rejects that premise. By engineering the cell so that sulfur is driven to and from the S+1 state, researchers have shown that the reaction itself is a design variable, and that the voltage and stability limits long treated as intrinsic to the chemistry can be moved. If the system-level engineering can be scaled, the humble sulfur cathode, long the almost-ran of the battery world, may at last claim the high-energy, long-life, low-cost future that has always been its promise.

Subject of Research: Halogen-assisted sulfur oxidation in lithium-sulfur batteries via disulfur dichloride formation

Article Title: Halogen-assisted sulfur oxidation

Article References: Halogen-assisted sulfur oxidation. (n.d.). https://doi.org/10.1038/s41560-026-02086-7

Image Credits: AI Generated

DOI: 10.1038/s41560-026-02086-7

Keywords: lithium-sulfur batteries, sulfur oxidation, disulfur dichloride, halogen chemistry, battery voltage, cycling stability, polysulfide shuttle, energy density, chlorine chemistry, energy storage, Nature Energy, battery sustainability

The crux of the challenge lies in the top cell of the stack. In a triple-junction architecture, three subcells with different bandgaps are stacked so that each absorbs a different slice of the solar spectrum: a wide-bandgap top cell captures the most energetic photons, while middle and bottom cells harvest the redder light that passes through. For an all-perovskite design, the top absorber needs a bandgap of roughly 2.0 electronvolts, which requires a perovskite composition dominated by bromide rather than iodide. The problem is that pushing the bromide-to-iodide ratio that high triggers a cascade of material pathologies—surface wrinkling, chemical inhomogeneity, and large open-circuit voltage deficits—that have historically throttled the performance of these ultrawide-bandgap films.

The Nanjing researchers traced these problems back to the physics and chemistry of film formation. When a mixed bromide-iodide perovskite precursor solution is spun into a thin film and crystallized, the two halides do not necessarily solidify in lockstep. Iodide-rich and bromide-rich regions can nucleate at different moments, leaving the finished film with local variations in halide composition. Those variations create tiny bandgap fluctuations across the film, which in turn generate internal stress as different regions of the crystal lattice strain to accommodate one another. The visible symptom is wrinkling of the film surface—morphological disorder that degrades the uniformity of the interface where charge extraction begins.

To combat this, the team developed a strategy they describe as surface reconstruction combined with halide homogenization, executed through synergistic solvent and additive engineering. The first element involves a solvent treatment that induces a controlled reconstruction of the perovskite surface, suppressing the wrinkle formation that normally accompanies crystallization of these high-bromide compositions. The second element is a transient chlorine additive delivered via oleylammonium chloride. During film formation, the chloride ions are temporarily incorporated into the crystal lattice, where they act as a chemical mediator: their presence synchronizes the crystallization of bromide and iodide, ensuring that both halides lock into the lattice at the same rate rather than segregating into iodine-rich and bromine-rich domains.

The payoff of this coordinated approach is visible at every scale the researchers examined. Kelvin probe measurements showed that the treated films exhibit a uniform surface potential, in contrast to the patchy electrostatic landscapes of conventional ultrawide-bandgap perovskites. Time-resolved spectroscopic characterization revealed suppressed non-radiative recombination—the parasitic process in which photoexcited carriers annihilate each other as heat rather than contributing to current—and improved carrier mobility. Most strikingly, the open-circuit voltage of a single-junction device built on the 2.0-eV absorber reached 1.46 volts, a figure that dramatically narrows the notorious voltage deficit that has plagued wide-bandgap perovskites and that represents a critical step toward the theoretical performance limits of multijunction stacks.

Open-circuit voltage is the parameter that matters most in a triple-junction cell. Unlike single-junction devices, where current is the chief battleground, a series-connected multijunction stack forces all three subcells to operate at the same current, and the total voltage is the sum of the individual subcell voltages. Every millivolt lost to recombination or halide disorder in the top cell subtracts directly from the module’s total output. By achieving a 1.46-volt open-circuit voltage from a 2.0-eV absorber, the Nanjing team recovered a substantial fraction of the voltage that previous designs forfeited, converting the material-science fix into a direct efficiency gain at the device level.

To build the full triple-junction device, the researchers integrated their improved ultrawide-bandgap top cell with two carefully optimized lower absorbers, with bandgaps of 1.6 and 1.22 electronvolts respectively. The resulting monolithic device, in which all three junctions are grown sequentially on a single substrate, delivered a power conversion efficiency of 30.1 percent under standard test conditions, with a certified value of 29.3 percent—an efficiency that places all-perovskite triple-junction technology in the same league as the best perovskite-silicon tandems while using only low-cost, solution-processable absorbers. Importantly, the devices also demonstrated robust operational stability, addressing one of the most persistent doubts about perovskite photovoltaics.

The significance of the work extends beyond a single record number. The field’s broader goal, as the authors note, is all-perovskite multijunction photovoltaics exceeding 35 percent efficiency—a threshold that would rival the performance of the III-V compound semiconductors used in space-grade solar panels at a small fraction of the manufacturing cost. Triple-junction architectures are the most credible route to that target, but they live or die by the quality of the ultrawide-bandgap top cell, because the 2.0-eV absorber must absorb the harsh blue end of the spectrum without squandering voltage. The demonstration that solvent-induced surface reconstruction and transient chloride incorporation can tame the crystallization of these difficult compositions offers the field a reproducible recipe, rather than a one-off material trick.

There are also practical signals in how the result was achieved. Both components of the strategy—solvent engineering and small-molecule halide additives—are compatible with existing deposition workflows for perovskite films, including the antisolvent and thermal annealing steps used across the industry. The approach required no exotic processing equipment or entirely new material system, which improves the odds that the technique can be scaled to larger areas and integrated into commercial production lines. The work, which involved collaborators at the Australian National University and ULVAC-PHI Instruments in addition to Nanjing University, has already resulted in a granted patent held with Renshine Solar, a perovskite commercialization company founded by Tan, underscoring the team’s intent to translate the laboratory result toward manufacturing.

For now, the result stands as the most convincing demonstration yet that all-perovskite triple-junction solar cells are a viable technology rather than a theoretical curiosity. By showing that the stubborn problems of surface wrinkling, halide heterogeneity, and voltage deficit in 2.0-eV perovskites can be resolved through a rational, chemistry-level understanding of crystallization, the Nanjing team has removed one of the central bottlenecks on the road to ultrahigh-efficiency, low-cost solar power. If subsequent studies can preserve these gains while scaling the films and extending device lifetimes, the 35-percent-efficiency milestone that once seemed distant may arrive sooner than expected.

The voltage figure reported for the ultrawide-bandgap subcell deserves particular attention when set against the radiative limit. A 2.0-electronvolt absorber in an ideal diode would deliver an open-circuit voltage approaching 1.7 volts under one-sun illumination, so the 1.46 volts achieved here still leaves a deficit, but one that is markedly smaller than the losses of roughly 0.7 volts or more that have typified high-bromide perovskites in earlier studies. Because voltage losses in mixed-halide films are largely attributable to non-radiative recombination at halide-segregation-induced defects, the observed improvement is consistent with the idea that homogenizing the bromide and iodide distribution removes the very sites where carriers were previously lost.

The transient role of the chloride additive fits a broader pattern in halide perovskite chemistry. Chloride has long been known to influence grain growth, crystallite orientation, and defect density in lead-halide films, but it typically remains in the lattice only in small quantities or is expelled during annealing. Using oleylammonium chloride as a delivery vehicle adds a further dimension: the long organic cation can interact with the precursor solution and the developing film surface, slowing nucleation and giving the bromide and iodide species time to intermix before the lattice locks in. The fact that chlorine is largely absent from the final absorber means the strategy improves the film without introducing a foreign species whose long-term stability might be questioned.

The characterization approach used by the team also reflects how perovskite research has matured. Kelvin probe force microscopy maps surface potential with nanoscale resolution, allowing researchers to see whether electrostatic inhomogeneity persists after treatment, while time-resolved photoluminescence distinguishes radiative from non-radiative decay pathways. Combining these probes with device-level measurements makes it possible to connect a processing intervention directly to the microscopic defect physics and then to the macroscopic efficiency gain, a chain of evidence that strengthens confidence that the improvement is mechanistic rather than coincidental.

It is also worth situating the result within the trajectory of the field. All-perovskite tandems crossed 29 percent efficiency only recently, and triple-junction perovskite devices have lagged behind their perovskite-silicon counterparts because the ultrawide-bandgap top absorber was the weakest link. The certified 29.3 percent reported here, achieved entirely with solution-processed perovskite absorbers, suggests that the remaining headroom toward 35 percent depends less on inventing new architectures than on continuing to reduce voltage losses and optical losses in each subcell. The operational stability data accompanying the efficiency figures will be scrutinized closely, since encapsulated multijunction devices must endure prolonged illumination and thermal cycling, but the demonstration that a heavily brominated top cell can be made both efficient and durable removes a long-standing objection to the all-perovskite approach.

Subject of Research: Crystallization control of ultrawide-bandgap 2.0-eV perovskite absorbers for high-efficiency all-perovskite triple-junction solar cells

Article Title: Crystallization control of 2.0-eV bandgap perovskites for all-perovskite triple-junction solar cells

Article References: Zhang, Y., Wang, E., Liu, H., Zhou, D., Lin, R., Li, H., Xu, D., Lou, J., Zhu, H., Li, M., Wang, Y., Duan, C., Zhu, Y., Bui, A. D., Nguyen, K., MacDonald, D., Yang, O., Ju, H., Li, L., … Tan, H. (2026). Crystallization control of 2.0-eV bandgap perovskites for all-perovskite triple-junction solar cells. Nature Energy. https://doi.org/10.1038/s41560-026-02135-1

Image Credits: AI Generated

DOI: 10.1038/s41560-026-02135-1

Keywords: perovskite solar cells, triple-junction, ultrawide-bandgap, crystallization control, halide homogenization, surface reconstruction, open-circuit voltage, power conversion efficiency, multijunction photovoltaics, oleylammonium chloride, non-radiative recombination, Nature Energy