Researchers at Case Western Reserve University have developed an electrolyte architecture that enables protons to conduct charge via a “hopping” mechanism, offering an alternative to volatile, flammable liquids that dominate conventional battery designs such as lithium‑ion.
The work, published in the Proceedings of the National Academy of Sciences, demonstrates how molecular structure can enable strong ionic transport even in thicker, less volatile fluids typically associated with safer flow battery chemistries.
Flow batteries are among the most scalable stationary storage technologies because their energy capacity scales with tank volume rather than electrode materials. This feature allows multi‑megawatt installations to store energy for hours to days, matching the intermittency profiles of high‑penetration solar and wind generation. However, commercial flow batteries often rely on organic electrolytes with low flash points or vanadium‑based aqueous systems that face supply chain constraints and limited energy densities.
The Case Western team’s structured electrolyte leverages a proton conduction mechanism akin to the Grotthuss process. In this mode, protons rapidly traverse a network of hydrogen bonds by transitory association and dissociation with adjacent molecules. That stands in contrast to vehicular ionic conduction, where ions physically diffuse through the liquid medium, a process that slows dramatically as fluid viscosity increases. The structured electrolyte sustains effective proton transport without necessitating low‑viscosity solvents, enabling safer, non‑volatile formulations that do not readily evaporate or ignite.
Safety concerns have been a persistent barrier to large‑scale adoption of conventional battery chemistries. Lithium‑ion systems, while energy dense, present risks of thermal runaway and fire due to flammable organic electrolytes — factors that constrain siting, regulatory approval, and life cycle management of grid storage assets. Flow batteries inherently dissipate heat better and isolate reactive chemistries in external tanks, but electrolyte stability and conductivity trade‑offs have limited performance. Advances like structured proton‑conducting liquids are significant because they offer an alternative pathway that mitigates flammability without sacrificing charge transport efficiency.
The researchers acknowledge that the current formulation requires further refinement in chemical solubility to enhance energy density — a critical parameter for storage systems intended to replace hours of renewable variability. Solubility limits directly affect how much active species the electrolyte can carry, influencing the overall energy stored per unit volume. Overcoming these limitations is essential for flow systems to compete with incumbent technologies on cost and footprint.
Proton conduction mechanisms are well studied in other electrochemical systems, including aqueous proton batteries and hydrogen fuel cells, where structural diffusion through hydrogen‑bond networks underpins rapid charge transport. Recent studies in aqueous proton environments have shown that engineered hydrogen‑bond pathways can significantly lower interfacial resistance and boost charge‑transfer kinetics. Integrating such principles into flow battery electrolytes could lead to high‑performance storage architectures that combine safety, longevity, and scalable design.
