Ultralow-concentration electrolyte boosting K0.486V2O5 for high-performance proton storage

High-concentration electrolytes are considered a promising tool for widening stable electrochemical windows and enhancing the performance of aqueous batteries. However, their high cost, viscosity, low conductivity remain thorny issues. Because special Grotthuss mechanism protons in water, proton batteries can use low-concentration electrolyte to obtain sufficient kinetic performance. Herein, we present an unusual, ultralow-concentration sulfuric acid (0.01 mol L−1) boost stability K-ion pre-intercalated V2O5 (K0.486V2O5, KVO). The KVO electrode exhibits reversible capacity approximately 129 mA h g−1 at current density 50 impressive retention 78% over 20,000 cycles 1 A g−1. Ultralow-concentration chemistry will open novel route exploit durable low-cost energy storage systems.