Zn anode sustaining high rate and high loading in organic electrolyte for rechargeable batteries

Abstract

Rechargeable aqueous Zn battery, the promising candidate for future energy storage devices still suffers from multiple disadvantages of low reversibility, uncontrolled dendrite growth, and limited electrochemical potential window. Alternatively, organic electrolytes can theoretically resolve the thermodynamic instability of Zn anode, but at the expense of high-rate capability due to their inferior ionic conductivity. Here we report N, N-dimethyl formamide (DMF) based non-aqueous electrolyte containing Cu2+ ions as an additive (Cu2+-DMF). The combined effect of high thermodynamic stability of Zn anode in DMF electrolyte and in-vitro Cu-Zn alloy interphase can surpass both aqueous and non-aqueous electrolyte performance. High-rate capability, low overpotential of ∼50 mV at 20.0 mA cm−2/20.0 mAh cm−2, supreme stability over 1400 h at 5.0 mA cm−2/5.0 mAh cm−2, high Coulombic efficiency (CE, ∼99.60 %) and wide electrochemical stability window (∼2.45 V vs. Zn/Zn2+) is observed for Cu2+-DMF electrolyte. As a proof-of-concept, Zn||δ-MnO2 battery configuration in DMF electrolyte exhibits stable cycling, high-rate capability, and excellent reversibility. For deep understanding, the electrochemical kinetics and storage mechanism are also validated through multiple characterization techniques. This work is a substantial step towards the cost-effective construction of rechargeable non-aqueous Zn ion batteries.