But making a LiF-based SEI usually comes with a drawback. Many LiF-forming electrolyte strategies rely on anions moving into the lithium-ion solvation environment. That rearrangement weakens the electrolyte’s ability to transport ions quickly. The result is a built-in compromise: improved interphase formation at the cost of lower ionic conductivity, which can undermine fast charging and performance in cold conditions.

In a new study, Chen, Huang, Zhang and co-workers report a solvent-bridged electrolyte design intended to decouple these conflicting requirements. Their approach starts with LiPF6 as the salt source, dissolved in a cosolvent system built around two distinct roles. One solvent type is a bridging cyclic ether that can “share” coordination between Li+ and PF6−, effectively solvating both species. The second solvent component is a structural linear ether that influences the electrolyte’s liquid-range behavior—helpful for keeping the electrolyte functional under harsh temperatures.

By reducing direct Li+–anion contact, the formulation encourages LiF-rich SEI formation without forcing the anions to fully enter the primary lithium solvation sheath. This balance is the core of the reported performance gains: higher ionic conductivity remains available for rapid ion transport, while the interphase still develops the protective LiF component associated with long cycling stability.

The implications are striking for extreme operating scenarios. The authors demonstrate stable cycling of micrometre-sized silicon anodes under fast charge rates exceeding 4 C, where time-dependent polarization typically accelerates degradation. Even more challenging, the electrolyte supports operation down to −55 °C, a temperature at which many conventional electrolytes suffer from sluggish ion motion or partial freezing.

The study also addresses an additional stressor: lithium plating. Under conditions that promote plating, a robust and well-composed SEI can determine whether deposited lithium becomes a durable component of the electrode or a catalyst for continued failure. The solvent-bridged strategy helps maintain favorable interphase chemistry while preserving transport properties.

Overall, solvent-bridged electrolytes offer a conceptually new way to manage the trade-off between SEI chemistry and conductivity. Rather than treating LiF-rich interphases and high-rate, low-temperature performance as mutually exclusive, the work suggests that solvent architecture can be engineered to satisfy both simultaneously, potentially accelerating the path toward high-energy cells that remain reliable in demanding real-world use.

Subject of Research: Solvent-bridged electrolytes for high-energy lithium-ion batteries

Article Title: Solvent-bridged electrolytes for high-energy Li-ion batteries under extreme conditions

Article References: Chen, Y., Huang, F., Zhang, Q. et al. Solvent-bridged electrolytes for high-energy Li-ion batteries under extreme conditions. Nat. Chem. (2026). https://doi.org/10.1038/s41557-026-02221-7

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41557-026-02221-7

The crux of this advancement lies in the deliberate engineering of the cathode surface chemistry. By employing a dopant pairing approach, the research team achieved a nearly 9-nanometer thick enriched layer of Ti^4+ near the surface of the NCM811 cathode particles. This titanium-rich surface layer was realized only through the specific presence of Na^+ ions, which appear to facilitate the incorporation and stabilization of Ti^4+ at levels far surpassing typical solubility limits—an effect described by the authors as supersaturation within the layered cathode matrix. Such supersaturation is a novel concept in cathode chemistry, where high-valence d^0 cations like Ti^4+ are introduced in a controlled manner to strategically modify the electrochemical interface.

The implications of achieving this Ti^4+ supersaturation at the cathode surface are profound. First and foremost, the titanium-enriched surface dramatically enhances the structural stability of the cathode material when cycled at ultra-high voltages of 4.8 V versus Li^+/Li. Normally, operating at such voltages accelerates lattice distortion, phase transitions, and the release of oxygen, leading to rapid capacity fade and safety concerns. The Ti^4+ ions act as stabilizing agents that help maintain the layered structure’s integrity, preventing detrimental transformations that would otherwise compromise battery performance.

Moreover, this Ti^4+-rich surface also effectively suppresses the side reactions occurring at the interface between the cathode and the electrolyte—one of the primary avenues for long-term degradation. Typically, at elevated voltages, the electrolyte undergoes oxidation, liberating oxygen (O_2) and carbon dioxide (CO_2) gases that degrade both the electrolyte and the cathode surface. The research reveals that with the dopant-paired Ti-Na surface modification, there is a marked reduction in the evolution of these gaseous species. This suppressed reactivity not only improves the chemical stability of the cathode but also contributes to enhanced safety by reducing gas accumulation inside the battery cell.

A critical consideration in high-energy batteries is how ionic transport evolves with cycling, particularly at harsh voltages that can induce surface reconstruction or impedance growth. The study shows that the Ti^4+-enriched surface layer preserves faster ion transport channels even after prolonged cycling at 4.8 V. This preservation is attributed to the stabilizing structural effects of titanium and the mitigating influence of sodium on lattice distortion, which collectively prevent the formation of resistive surface phases that typically block lithium ion migration.

The significance of incorporating high-valence d^0 cations such as Ti^4+ goes beyond just physical stability. These ions inherently exhibit strong electrostatic interactions that limit oxygen release and lattice oxygen activity, mitigating one of the principal drivers of cathode degradation. Na^+, a larger alkali ion, complements this effect by modifying the local environment, making it thermodynamically favorable to maintain such a high Ti^4+ concentration that otherwise would be unattainable in conventional doping techniques. This synergy between Ti and Na represents an unprecedented control over the cathode’s chemical landscape.

From an engineering perspective, the methodology to achieve this dopant pairing does not rely on complicated or costly processes. Instead, it involves a carefully designed synthesis protocol where Na^+ ions act as a mediator during the doping stage, allowing excess Ti^4+ to be incorporated at the surface without forming unwanted bulk phases or surface defects. This approach can be potentially generalized to other layered oxide cathode systems, indicating a new paradigm for high-voltage battery design.

The practical outcomes of this innovation manifest in enhanced cycling stability and capacity retention under extreme operational voltages. While traditional NCM811 cathodes rapidly lose capacity when charged beyond 4.3 V, the Ti-Na doped variants maintain a significantly higher fraction of their initial capacity after hundreds of cycles at 4.8 V. Such performance not only extends the functional lifespan of batteries but also opens avenues for their use in demanding applications such as electric vehicles operating in extreme climates or aerospace systems requiring dependable high energy storage.

Furthermore, the insights gleaned from this dopant-pairing strategy elucidate fundamental aspects of cathode degradation mechanisms. By stabilizing the surface environment chemically and structurally, the approach effectively decouples the cathode’s electrochemical activity from harmful side processes. This decoupling could inspire future research lines focusing on targeted surface chemistry modulation to address specific degradation pathways.

It is also notable that this innovation comes at a time when the lithium-ion battery industry is aggressively pursuing pushes toward higher voltages and energy densities, with the aim of surpassing current market thresholds. Existing techniques like surface coatings or bulk compositional tweaks have struggled with the competing demands of stability and conductivity at these voltages. This dopant-pairing concept offers a fresh, well-substantiated direction grounded in fundamental electrochemistry and material science.

Looking forward, the potential for this methodology to be integrated into commercial cathode production offers promising prospects. The scalable nature of doping processes and the use of abundant elements such as Ti and Na make this approach feasible for industrial adaptation. Enhanced cathodes based on this principle could influence the next wave of electric vehicle batteries, grid storage solutions, and advanced portable electronics, pushing the envelope of what rechargeable lithium-ion technology can achieve.

In summary, the reported dopant-pairing technique setting a supersaturated Ti^4+ surface layer stabilized by Na^+ ions represents a transformative advancement in lithium-ion battery cathode design. It strikes a critical balance between boosting energy density through higher charging voltages and maintaining the structural and chemical resilience necessary for long-term cycling. This work exemplifies how clever manipulation of cathode chemistry at the nanoscale can yield outsized improvements in battery performance, potentially reshaping the landscape of energy storage technologies for years to come.

Subject of Research: High-voltage stability enhancement of Ni-rich layered lithium-ion battery cathodes via supersaturated high-valence cation doping.

Article Title: Exceptional layered cathode stability at 4.8 V via supersaturated high-valence cation design.

Article References:
Liao, H., Tang, Y., Ma, W. et al. Exceptional layered cathode stability at 4.8 V via supersaturated high-valence cation design. Nat Energy (2025). https://doi.org/10.1038/s41560-025-01831-8

Image Credits: AI Generated

The research introduces a unique PFA-COOH-CNT artificial SEI film synthesized using biomass-derived furfuryl alcohol (FA) in combination with carboxyl functionalized carbon nanotubes (COOH-CNT). The significance of this artificial SEI film lies in its unique properties that promote the uniform deposition of zinc ions while concurrently inhibiting the detrimental side reactions that typically plague zinc anodes. This innovation addresses crucial challenges such as zinc dendrite growth and the hydrogen evolution reaction (HER), which are commonly responsible for the cycles’ limited lifespan in current systems.

The PFA-COOH-CNT membrane achieves noteworthy performance metrics, including an ultra-long cycle life of 2200 hours at current densities of 1 mA‧cm⁻² and specific capacities of 1 mAh‧cm⁻². These metrics far exceed those observed in conventional zinc||zinc symmetric batteries, which typically demonstrate a cycle stability of only 418 hours under similar conditions. The ability of this artificial SEI film to create a stable and efficient operating environment for zinc anodes marks a significant step forward in battery technology.

As the research suggests, the successful incorporation of the PFA-COOH-CNT SEI film leads to a more uniform deposition of zinc ions during the electrochemical processes involved in plating and stripping. This uniformity is crucial as it minimizes the formation of zinc dendrites, mitigating one of the principal causes of battery failure. Furthermore, by effectively hindering the direct contact between the aqueous electrolyte and the zinc anode through hydrophobic properties, the artificial SEI film reduces the likelihood of HER occurrences. This dual functionality is key in enhancing the overall efficiency and longevity of the battery.

In a broader context, the achievement of rechargeable full cells using the PFA-COOH-CNT technology indicates impressive reversible capacities. For instance, the PFA-COOH-CNT@Zn||V₂O₅ full cell exhibits remarkable electrochemical performances, showcasing a reversible capacity of 150.2 mAh‧g⁻¹ at a high current rate of 1 A‧g⁻¹ after 400 cycles. Such results represent a critical advancement in the feasibility of using zinc-based batteries for sustainable energy storage solutions.

This innovation stems from detailed research into the properties of zinc-ion deposition. Professor Gu emphasized the impactful role that both zincophilic and hydrophobic characteristics play in enhancing anode performance. The traditional barriers faced by aqueous zinc-ion batteries are largely attributed to uneven electric field distributions caused by dendrite formation, the phenomenon known as "dead zinc," and the irreversible corrosion catalyzed by HER. By expertly leveraging the properties of the newly designed SEI film, the team effectively stabilizes the zinc anode, paving the way for enhanced cyclic performance.

The creation of hybrid artificial SEI membranes has emerged as a superior alternative to conventional designs, which often fall short during the repetitive charging and discharging cycles of batteries. The inorganic layers can detach under continuous cycling, whereas the organic materials lack sufficient zincophilic properties. In contrast, the innovative combination of FA and COOH-CNT in the newly designed membrane provides both structural robustness and excellent functional performance, drastically reducing the chances of failure.

On a molecular level, the process of synthesizing the artificial SEI involves the esterification of FA and COOH-CNT under acidic conditions, followed by heating. This reaction leads to the formation of a three-dimensional porous framework that houses a plethora of zincophilic groups. Additionally, the self-polymerization of FA into polyfurfuryl alcohol results in a compact and homogenous film that adheres tenaciously to the zinc surface. This critical amalgamation of functionalities boosts the zinc anode’s performance significantly.

The implications of this research extend far beyond zinc-ion batteries, revealing opportunities for application in various energy storage systems. The simple and cost-effective methodology described offers a path toward the development of sustainable battery technologies that could better meet the world’s growing energy demands. Scalability is a crucial aspect of this technology, and its straightforward application using readily available raw materials emphasizes its potential for future development in the field.

Supporting the findings, researchers from the Technical Institute of Physics and Chemistry in Beijing contributed significantly to the project, highlighting a collaborative effort that broadens the scope of impact. Through substantial funding from institutions such as the National Natural Science Foundation of China and other academic grants, this research stands as a testament to the importance of interdisciplinary cooperation in the field of renewable energy.

The future of energy storage appears promising with such advancements in technology and material science. The dual-functionality of PFA-COOH-CNT membranes not only paves the way for longer-lasting battery systems but also demonstrates a commitment to tackling global energy challenges with innovative solutions. The hope is that these developments will lead to greater efficiency, sustainability, and reliability in energy storage solutions globally.

This innovative pursuit towards zinc anode stabilization signals a critical milestone in advancing not only battery technologies but also in promoting a deeper understanding of electrochemical processes. Researchers expect that the enhanced stability and performance could lead to exciting advancements in various applications, including consumer electronics, electric vehicles, and renewable energy storage solutions, thereby ushering in a new era in battery technology.

The outcome of this research emphasizes the value of strategic innovation in energy storage solutions, showcasing how scientific inquiry can lead to transformative developments in technology. The future not only looks brighter for zinc-ion technologies but also reaffirms the importance of continued research and collaboration in overcoming the challenges posed by energy storage applications.

Subject of Research: Development of dual-function artificial SEI membrane for zinc anodes
Article Title: Zincophilic and hydrophobic bifunctional PFA-COOH-CNT artificial SEI film for highly stable Zn anode
News Publication Date: 8-Jan-2025
Web References: Nano Research
References: National Natural Science Foundation of China
Image Credits: Nano Research, Chongqing Technology and Business University

Keywords

Energy storage, zinc-ion batteries, solid electrolyte interphase, artificial membranes, battery technology, charge cycles, dendrite inhibition, electrochemical performance, sustainability, hybrid materials, nanoscale innovation, biomass materials.