The project, titled “Controlling dimensionality and ligand connectivity to tune intercalation properties in transition metal oxychlorides,” addresses one of the central challenges facing rechargeable batteries: how to develop high-performing materials from elements that are abundant, affordable, and less vulnerable to supply-chain limitations. Lithium-ion batteries have become essential in electric vehicles, consumer electronics, and renewable-energy systems, but many of their constituent materials depend on geographically concentrated resources and complex refining networks.

Grimaud, an associate professor of chemistry who joined Boston College in 2022, leads a research group focused on the fundamental chemistry of electrochemical interfaces. These interfaces are the regions where electrodes and electrolytes meet, and they govern how ions move, how electrons flow, and how battery materials change during charging and discharging. A material that appears promising in isolation may perform poorly in a working battery if it reacts unfavorably with the surrounding electrolyte.

“The same battery material may succeed or fail depending on the electrolyte surrounding it,” Grimaud explained. His team is therefore studying not only the solid electrode materials themselves but also the chemical environment in which they operate. Electrolytes—liquids or solids that transport ions between battery electrodes—can influence the stability, reversibility, voltage, and lifetime of a cell. By designing electrolytes with adjustable chemical properties, researchers may be able to make previously unstable materials function reliably.

The new NSF-supported research will focus on mixed-anion materials containing both oxygen and chlorine. In conventional battery compounds, oxygen is often the dominant negatively charged element, or anion. Replacing or combining oxygen with another anion can change the electronic structure, bonding, crystal geometry, and reactivity of a material. Those changes may determine how easily lithium or sodium ions can enter and leave the structure, a process known as intercalation.

During intercalation, ions move reversibly into spaces within a host material without completely destroying its framework. This process is fundamental to the operation of many rechargeable batteries. When a battery charges, lithium or sodium ions migrate into the electrode; when it discharges, they move back while electrons travel through an external circuit. The speed, capacity, and durability of this process depend on the pathways available for ion movement and on whether the host structure can withstand repeated chemical and structural changes.

Grimaud’s team has already achieved reversible lithium intercalation in several oxychloride materials. In one demonstration, a compound composed of iron, oxygen, and chlorine delivered energy density and electrochemical performance comparable to an established iron-and-phosphate material. Iron, oxygen, and chlorine are relatively abundant and inexpensive elements, while phosphate-based materials can be tied to sourcing and refining constraints and may compete with agricultural uses for phosphate resources.

The researchers now aim to determine how the dimensionality of these compounds and the connectivity of their chemical building blocks affect ion storage. In materials science, dimensionality describes whether a structure forms isolated units, chains, sheets, or three-dimensional networks. Ligand connectivity refers to the way atoms or molecular groups bind to a central metal and to one another. Adjusting these features could allow scientists to tune a material’s voltage, capacity, conductivity, structural stability, and selectivity for lithium or sodium.

The implications extend beyond batteries. Grimaud said that precise control over the electronic and structural properties of oxychloride materials could open possibilities in electronics and quantum technologies, where unusual electrical, magnetic, or optical behaviors are valuable. The work may also support the development of sodium-ion batteries, which are attracting interest as a complement to lithium-based systems because sodium is widely distributed and potentially easier to source at large scale.

The CAREER Award will support both laboratory research and educational programs. Grimaud plans to use findings from the project to introduce Boston College students to the links between materials design, energy technology, and environmental consequences. He will also work with students in grades eight through twelve who participate in The Academy, a free enrichment program supported by Boston College’s Pine Manor Institute for Student Success. Laboratory activities will introduce these students to battery chemistry while encouraging them to consider how raw materials are sourced, refined, used, and eventually recycled.

As battery technologies expand rapidly, Grimaud argues that performance alone cannot define progress. Future materials must be evaluated alongside their social and ecological costs, including mineral availability, energy-intensive processing, waste, and geopolitical dependence. By combining fundamental chemistry with education and broader sustainability questions, the project aims to develop better battery materials while preparing a new generation of scientists to think critically about the technologies they create.

Subject of Research: Battery materials chemistry, transition metal oxychlorides, lithium- and sodium-ion batteries, electrochemical interfaces, and tunable electrolytes

Image Credits: Boston College

Keywords

Chemistry, energy, electrochemistry, electrochemical cells, batteries, battery materials, lithium-ion batteries, sodium-ion batteries, materials science, quantum technologies, National Science Foundation, Boston College

Traditionally, the science of solid–electrolyte interphase (SEI) formation and electrode–electrolyte interactions has been dominated by classical electric double layer models. While these models have provided useful macroscopic insight, they fall short of capturing the complex, molecular-level negotiations that occur in this interfacial region. Interactions among ions and solvent molecules—critical to the battery’s operation—are governed by nuanced thermodynamic and kinetic principles that classical approaches oversimplify. The team’s study addresses this gap by incorporating both thermodynamic and kinetic aspects of the ISS, offering unprecedented clarity on mechanisms like ion migration, desolvation, and interfacial coordination structures.

A key revelation from this research is the recognition that the chemistry at the electrode-electrolyte interface is not static. Instead, it is a highly dynamic milieu where solvation structures evolve continuously throughout battery cycling. The ISS impacts how ions coordinate near the electrode surface, influence charge transfer rates, and control the nature and quality of the resulting SEI layer. Such a layer is crucial—it acts as a protective film, permitting ion conduction while preventing detrimental side reactions. By better understanding the ISS’s behavior, researchers seek to tailor these interphases for optimal ion transport and mechanical robustness.

One of the central challenges the researchers tackled was deciphering how ion-solvent interactions shift under practical operation conditions. These conditions—characterized by moderately concentrated electrolytes—are especially difficult to model due to the heterogeneity of species present and the fluctuations induced by electrochemical cycling. Sophisticated computational simulations allied with cutting-edge spectroscopy provided the team with atomic-level insights into how anions and additives in the electrolyte orchestrate the ISS evolution. Crucially, they demonstrated that enriching the ISS with carefully selected anions and additives substantially enhances the conductive and mechanical properties of the SEI.

This strategic manipulation of interfacial chemistry is transformative. By promoting anion- and additive-rich interfacial solvation structures, the formed SEI is not only mechanically resilient but also highly conductive, greatly elevating Coulombic efficiency. Such modified ISSs expand the electrochemical stability window, enabling batteries to function safely and efficiently even under extreme current densities or elevated temperatures. This robustness marks a significant leap forward, addressing one of the most persistent bottlenecks in secondary battery technology: ensuring long cycle life without sacrificing energy density or operational safety.

The interplay of kinetics and thermodynamics in the ISS also governs ion desolvation—a critical step where ions shed their solvation shells before embedding into the electrode. Improved control over desolvation kinetics results in faster charge and discharge rates, reducing overpotentials and enhancing overall rate capability. Ye and colleagues uncovered that by optimizing the ISS composition, desolvation can be accelerated, pushing battery performance closer to theoretical maximums. This insight is especially pertinent for high-power applications such as electric vehicles and renewable energy storage, where rapid charge acceptance is vital.

To uncover these phenomena, the researchers employed a multidisciplinary approach combining advanced spectroscopic methods, electrochemical characterizations, and molecular dynamics simulations. Techniques like synchrotron-based X-ray scattering and nuclear magnetic resonance provided real-time, in situ views of the coordination environments at the interface. Meanwhile, computational models dissected the energetics and pathways of ion migration and solvent dynamics. This powerful coupling of experiment and theory enabled the disambiguation of complex molecular signals that have historically obscured the understanding of ISS dynamics.

What sets this study apart is its inspiration drawn from a seemingly unrelated field: electrocatalysis. In electrocatalysis, the impact of electrolyte effects and interfacial structuring on catalytic performance has been meticulously investigated, generating a rich body of knowledge. The authors leveraged these concepts to redefine how battery scientists view electrolyte-electrode interactions. By adopting analogous frameworks, they demonstrated that battery interphases could be engineered with molecular precision to optimize performance, just as catalysts are tailored for maximum activity and selectivity.

Looking ahead, the implications of harnessing the interfacial solvation structure are profound. Besides enhancing traditional lithium-ion chemistries, the principles unveiled by this research appear readily translatable to emerging battery chemistries such as sodium-ion, magnesium-ion, and solid-state batteries. In all these systems, controlling the precise arrangement and evolution of ions and solvents at the interface will be essential to overcome current limitations in capacity, safety, and cycle life.

Moreover, the ability to regulate ISS properties brings exciting possibilities for battery operation in extreme environments—high temperatures, fast charging conditions, and high-voltage regimes. Such robustness could unlock new markets and applications that have remained elusive due to stability concerns. In parallel, this work charts a promising path toward developing rational electrolyte additives and formulations that “program” the interfacial chemistry for bespoke performance goals.

Beyond empirical trial and error, the approach adopted by Ye, Tu, Zhang, and collaborators represents a paradigm shift toward predictive design informed by atomistic-level understanding. This will accelerate innovation cycles, reduce development costs, and enable battery systems that meet the demanding energy storage needs of the future. The interdisciplinary strategies highlighted in their work make clear that collaboration between electrochemists, spectroscopists, and computational scientists is indispensable for tackling such complex electrochemical interfaces.

In essence, this study redefines the interfacial region in battery electrochemistry not as a passive boundary but as a dynamic, engineerable space whose properties dictate macroscopic battery behavior. By harnessing the rich complexity of the interfacial solvation structure, researchers have opened a new frontier for performance optimization. It is a testament to how advances in fundamental science can directly drive technological breakthroughs critical to a sustainable energy future.

As battery technology continues its rapid evolution, these insights empower the design of materials and electrolyte systems that deliver not just incremental improvements but transformative gains. The future of energy storage may well hinge on controlling the invisible—but powerful—molecular choreography at the electrode-electrolyte interface. This pioneering work embodies a milestone in that journey.

For engineers, materials scientists, and electrochemists alike, these findings serve as both a challenge and an invitation: to explore and exploit the dynamic molecular science of the interfacial solvation structure in pursuit of ever more efficient, safe, and durable battery technologies. The roadmap laid out by Ye, Tu, Zhang, and their team promises a new era where controlling chemistry at the nanoscale directly translates to global impact in energy storage.

Subject of Research: Interfacial solvation structure (ISS) dynamics and their role in secondary battery performance.

Article Title: Harnessing interfacial solvation structure for next-generation secondary batteries.

Article References:
Ye, C., Tu, S., Zhang, SJ. et al. Harnessing interfacial solvation structure for next-generation secondary batteries. Nat Energy (2026). https://doi.org/10.1038/s41560-025-01937-z

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41560-025-01937-z