Designing High-Donicity Anions for Rechargeable Potassium Superoxide/Peroxide Batteries

Abstract

A battery cathode based on the superoxide/peroxide redox not only inherits the advantage of oxygen (O2) batteries in high capacities and low costs but also overcomes the disadvantages in O2 storage, electrolyte evaporation, and anode deactivation due to O2 crossover. Herein, we report an enhanced potassium superoxide (KO2)/peroxide (K2O2) conversion by adopting a high-donicity anion additive in the ether-based electrolyte. Such an anion was synthesized via a “Solvent-in-Anion” strategy and validated to enhance the electron donicity of the electrolyte. The use of high-donicity anion could lead to enhanced KO2 utilization (≈90.2 %) by retarding electrode passivation and allow the full charging back of K2O2 through the solution-mediated pathway without electrocatalysts. No apparent cell degradation is observed during the first 120 cycles by controlling the reversible depth-of-discharge capacity at 292 mAh g−1 (Formula presented.) within an O2-free region. The K−KO2 cell delivers a high energy efficiency (>84.4 %) and a lifespan of over 1440 hours.