Ultrafast Nucleation Reverses Dissolution of Transition Metal Ions for Robust Aqueous Batteries

Abstract

The dissolution of transition metal ions causes the notorious peeling of active substances and attenuates electrochemical capacity. Frustrated by the ceaseless task of pushing a boulder up a mountain, Sisyphus of the Greek myth yearned for a treasure to be unearthed that could bolster his efforts. Inspirationally, by using ferricyanide ions (Fe(CN)<inf>6</inf>^3-) in an electrolyte as a driving force and taking advantage of the fast nucleation rate of copper hexacyanoferrate (CuHCF), we successfully reversed the dissolution of Fe and Cu ions that typically occurs during cycling. The capacity retention increased from 5.7% to 99.4% at 0.5 A g^-1after 10,000 cycles, and extreme stability of 99.8% at 1 A g^-1after 40,000 cycles was achieved. Fe(CN)<inf>6</inf>^3-enables atom-by-atom substitution during the electrochemical process, enhancing conductivity and reducing volume change. Moreover, we demonstrate that this approach is applicable to various aqueous batteries (i.e., NH<inf>4</inf>⁺, Li⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺, and Al³⁺).