Peking University researchers, led by Professor Pan Feng from the School of Advanced Materials, have unveiled fundamental mechanisms governing proton storage and transport within aqueous batteries, a breakthrough poised to significantly enhance energy storage safety and performance. Published in Matter on July 7, 2025, their study, "Proton storage and transfer in aqueous batteries," provides critical insights into how hydrogen-bond network engineering facilitates efficient proton movement, potentially leading to safer, faster-charging, and higher-capacity alternatives to conventional lithium-ion systems. This development holds substantial market significance for grid-scale storage, portable electronics, and electric vehicles, addressing a longstanding challenge in the energy sector.

Aqueous batteries, which utilize water-based electrolytes, inherently offer superior safety profiles compared to flammable organic-electrolyte lithium-ion counterparts. However, they have historically faced limitations in energy density. Protons (H⁺), with their exceptionally low mass and high mobility, represent ideal charge carriers for high-performance systems, yet their complex electrochemical behavior has hindered widespread practical application. Pan's team has now definitively demonstrated that protons move through a unique Grotthuss-type mechanism, characterized by rapid hopping between hydrogen bonds rather than traditional diffusion like metal ions. This "diffusion-free" transport mode is key to achieving the ultra-fast kinetics required for next-generation battery performance.

The research not only clarifies proton behavior but also proposes a unified framework for optimizing aqueous battery performance through precise hydrogen-bond network engineering. The team outlines three core strategies. First, in electrode design, they advocate for embedding water-containing or anhydrous hydrogen-bond networks directly within solid-state materials to establish well-defined, efficient pathways for proton transport. Second, through electrolyte tuning, the study illustrates that meticulous adjustment of acid concentrations and anion types within the electrolyte can significantly stabilize and enhance overall proton conductivity. Third, regarding interface engineering, the researchers demonstrated that modifying electrode surfaces, for instance by introducing hydroxyl (–OH) and carboxyl (–COOH) groups via oxygen plasma treatment, can create crucial proton-bridging channels. These channels are shown to substantially lower interfacial charge-transfer resistance, thereby improving reaction kinetics and overall battery efficiency.

This comprehensive study provides a robust theoretical foundation for developing advanced proton-based aqueous batteries that combine the inherent safety of water-based systems with performance metrics that could rival or surpass current lithium-ion technology. By strategically engineering hydrogen-bond networks, future battery designs could achieve unprecedented energy densities, significantly faster charging rates, and extended operational lifespans, accelerating the transition towards more sustainable and reliable energy infrastructure across diverse applications.