Novel electrolyte assisted ultralow-temperature zinc battery

Abstract

Secondary battery is an indispensable component in energy storage as it can uninterruptedly store the energy and release it when being required. Among them, zinc (Zn) rechargeable battery gains much attention due to its cost advantage. However, poor climate adaptation much weaken the competitiveness, and temperature-induced deterioration can be mainly blamed on the slow reaction-kinetics of Zn anode under low temperature. Under this scenario, an anti-freezing electrolyte with Zinc (II)Bis(trifluoromethanesulfonyl)imide (Zn(TFSI)2) salt and ternary solvents of acetonitrile (AN), methyl acetate (MA) and dichloromethane (DCM) is proposed. It successfully broadens the working temperature of Zn secondary battery to − 90 °C. The elaborately regulated solvation can ensure smooth ion-transfer in liquid zone, more importantly, it expedites the desolvation without much affecting the interface transportation. With the optimized electrolyte configuration, reversible Zn plating/stripping at ultra-low temperature has been realized. The Zn|polytriphenylamine (PTPAn) battery thus can reserve 70 % capacity at − 80 °C, and present extremely stable cycling and impressive rate capability at − 80 °C and − 60 °C. The results well address the kinetics issues encountered in the low-temperature Zn secondary battery, and reveals that only with appropriate solvation, the high ion-permeability of the interface as well as easy de-solvation can be guaranteed. The work provides a guideline for designing advanced electrolyte, and supplies a reliable and effective strategy for the all-weather electrochemical energy storage.