Understanding proton storage, transfer in aqueous batteries

Researchers from Peking University, led by Professor Pan Feng, have uncovered key mechanisms that govern how protons are stored and transported in aqueous batteries. Their research findings, published in the journal Matter, provide critical insights that could lead to safer, faster-charging and higher-capacity alternatives to lithium-ion batteries. The study also reveals how hydrogen-bond network engineering enables efficient proton storage and transport.

Aqueous batteries, which use water-based electrolytes, are safer than lithium-ion systems but have traditionally suffered from lower energy density. Protons, due to their low mass and high mobility, hold great promise, but their complex chemistry has limited real-world application. Feng’s research demonstrates that protons move through a Grotthuss-type mechanism, hopping between hydrogen bonds rather than diffusing like metal ions. This allows for ultra-fast, “diffusion-free” transport and positions protons as suitable charge carriers for high-performance aqueous batteries.

The research addresses a longstanding challenge in energy storage: achieving safety and high performance. By revealing how hydrogen-bond networks facilitate proton storage and transport, the study lays a theoretical foundation for a new generation of energy systems that could match or exceed lithium-ion technology. Unlike lithium (Li⁺) and sodium (Na⁺), which form stable ionic bonds with oxygen in rigid crystal frameworks, protons (H⁺) form more covalent, saturable H–O bonds and do not integrate into lattices in the same way.

The study proposes three core strategies to optimise aqueous battery performance using hydrogen-bond network engineering. First, in electrode design, the researchers suggest embedding water-containing or anhydrous hydrogen-bonded networks within solid-state materials to create well-defined pathways for proton transport. Second, through electrolyte tuning, the researchers demonstrate that adjusting the concentration of acids and the type of anions present in the electrolyte can stabilise and enhance proton conductivity. Third, in terms of interface engineering, the researchers showed that modifying the electrode surface, such as by introducing hydroxyl (–OH) and carboxyl (–COOH) groups using oxygen plasma treatment, can create proton-bridging channels that lower interfacial charge-transfer resistance and improve reaction kinetics.

These three strategies form a framework that clarifies proton behaviour in aqueous systems and paves the way for safer, faster and more efficient energy storage.

The study supports the development of next-generation, proton-based aqueous batteries that combine safety with high performance. By engineering hydrogen-bond networks, future devices could achieve higher energy density, faster charging and longer lifespan, thereby advancing applications from grid storage to portable electronics and electric vehicles.

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