Tetraethylene Glycol Dimethyl Ether (TEGDME)-Water Hybrid Electrolytes Enable Excellent Cyclability in Aqueous Zn-Ion Batteries

Abstract

Aqueous zinc-ion batteries (AZIBs) are considered hopeful large-scale electrochemical energy storage devices because of their simple production process, high specific capacity, intrinsic safety and low cost. However, the dendritic growth of Zn and side reactions cause rapid battery performance degradation, which limits the application of AZIBs for large-scale energy storage. In this work, following the addition of tetraethylene glycol dimethyl ether (TEGDME) to 1 mol L−1 (M) Zn(CF3SO3)2 aqueous electrolyte as a cosolvent, the 1 M Zn(CF3SO3)2/TEGDME-H2O (1:1 by volume) hybrid electrolyte showed enhanced battery performance resulting from the expanding electrochemical window, inhibiting the growth of zinc dendrites and the parasitic reactions on the negative Zn electrode. The experimental results show that this hybrid electrolyte enabled a high coulombic efficiency (CE) of >99% for 200 cycles in the Zn||Cu battery and a steady discharge/charge property for 1000 h with a low overpotential of 100 mV at 1 mA cm−2 (the capacity: 1.13 mAh) in the Zn||Zn battery. Remarkably, Zn||V2O5 batteries with the hybrid electrolyte also performed much better in terms of cycling stability than a device with a 1 M Zn(CF3SO3)2 aqueous electrolyte. Zn||V2O5 batteries delivered a high specific capacity of 200 mAh g−1 with an average CE of >99.9% after 1500 cycles at 0.5 A g−1. This study provides a promising strategy for the development of high-performance electrolyte solutions for practical rechargeable AZIBs.

Keywords

• aqueous zinc-ion battery
• electrolyte
• cosolvent
• tetraethylene glycol dimethyl ether
• vanadium pentoxide