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

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 similar to 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, similar to 99.60 %) and wide electrochemical stability window (similar to 2.45 V vs. Zn/Zn2+) is observed for Cu2+-DMF electrolyte. As a proof-of-concept, Zn||delta-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.

Automated summary

This study reports a non-aqueous electrolyte based on N, N-dimethyl formamide (DMF) with Cu2+ ions as an additive (Cu2+-DMF). The electrolyte exhibits high thermodynamic stability of the zinc anode and the advantage of Cu-Zn alloy interface, resulting in high-rate capability, supreme stability, and a wide electrochemical stability window.