Electrolyte Regulation of Bismuth Ions toward High-Performance Aqueous Manganese-based Batteries

Aqueous manganese (Mn)-based batteries in cathode solid/ liquid MnO2/Mn2+ chemistry have attracted widespread attention thanks to their high theoretical capacity and long cycle stability. However, the sluggish kinetics of solid-state anode reactions is accountable for the limited Mn-based battery performance at high rates. In this study, we report aqueous MnO2-Cr (Bi) batteries with excellent electrochemical performance that are achieved via the electrolyte regulation of Bi3+ for both the MnO2 cathode and liquid-state Cr anode reactions. Compared with the pristine MnO2-Cr cell, the electrochemical performance of the MnO2-Cr (Bi) cell regulated by the Bi3+ in the electrolyte is significantly improved. Specifically, our MnO2-Cr (Bi) full cell exhibits a low overpotential of 89 mV, a discharge voltage of 1.55 V, and high energy efficiency of 91.4% at relatively low rates. Moreover, a stable lifetime of 12 000 cycles at a rate of 200 C and an ultrahigh rate of 400 C with a discharge plateau above 1 V is achieved. The exciting results demonstrate that the aqueous MnO2-Cr (Bi) cells are of great interest for the deployment of economical and practical batteries for large-scale energy storage applications.