Triggering aqueous electrolyte molecular association via solvent eutectic strategy to enable zinc metal battery operation at −60℃

Abstract

It is a great challenge to circumvent the performance deterioration of aqueous zinc metal batteries (AZMBs) at low temperatures, which root from solvent solidification of water. Herein, via triggering aqueous electrolyte molecular association by solvent eutectic strategy, an aqueous solvent eutectic electrolyte of DMF-H2O solvent (SE-electrolyte) is prepared for adapting to the application of zinc metal battery at low temperature. The SE-electrolyte reduces the content of free water molecules, lowers the freezing point of the electrolyte, thus avoiding side reactions and broadening the operating temperature range of zinc batteries to −60℃. At room temperature, Zn||PANI full battery can cycle stably more than 10,000 times at 2 A/g high discharge current, the capacity retention rate is about 50%, and the average Coulomb efficiency is 99.79%. Under the harsh conditions of −45℃ and −60℃, the Zn||PANI whole battery can be stably cycled more than 1000 cycles with the current density of 0.2 A/g, and the Coulomb efficiency is close to 100%. The excellent low temperature electrochemical performance of SE-electrolyte indicates a bright prospect for the use of aqua zinc batteries in low temperature, and is a key step for the comprehensive and extensive application of aqueous zinc metal batteries.