Reconfiguring the Hydrogen Networks of Aqueous Electrolyte to Stabilize Iron Hexacyanoferrate for High‐Voltage Decoupled Cell

Abstract Prussian blue analogs (PBAs) are promising insertion‐type cathode materials for different types of aqueous batteries, capable of accommodating metal or non‐metal ions. However, their practical application is hindered by their susceptibility to dissolution, which leads to a shortened lifespan. Herein, we have revealed that the dissolution of PBAs primarily originates from the locally elevated pH of electrolytes, which is caused by the proton co‐insertion during discharge. To address this issue, the water‐locking strategy has been implemented, which interrupts the generation and Grotthuss diffusion of protons by breaking the well‐connected hydrogen bonding network in aqueous electrolytes. As a result, the hybrid electrolyte enables the iron hexacyanoferrate to endure over 1000 cycles at a 1 C rate and supports a high‐voltage pH‐decoupled cell with an average voltage of 1.95 V. These findings provide insights for mitigating the dissolution of electrode materials, thereby enhancing the viability and performance of aqueous batteries.