High-performance Zn-graphite battery based on LiPF6 single-salt electrolyte with high working voltage and long cycling life

Zinc-ion batteries (ZIBs) are promising alternative energy storage devices to lithium-ion batteries owing to the merits of large abundance, high theoretical capacity, and environmental friendliness. However, critical challenges including low working voltage (below 2 V), low energy density as well as dendrites formation during long cycling caused by aqueous ZIB systems still hinder their practical applications. Herein, a high-voltage Zn-graphite battery (ZGB) based on a non-zinc ion single-salt electrolyte (2.5 M LiPF6 in carbonate solvent) is developed. Moreover, we surprisingly found that Zn2+ is dissolved in the LiPF6 single-salt electrolyte during resting and discharging processes, thus enabling reversible Zn plating/stripping mechanism on the Zn foil anode in the ZGB over the voltage window of 1.0-3.1 V. As a result, the ZGB achieves long-term cycling performance with a capacity retention of similar to 100% for over 1200 cycles at 3C and high Coulombic efficiency of similar to 100% in 1.0-3.1 V with no dendrites formation. Moreover, the ZGB exhibits a high working voltage of up to 2.2 V, thus contributing to both high energy density (up to 210 Wh kg(-1)) and high power density (up to 1013 W kg(-1)), superior than most reported ZIBs. (C) 2020 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

A high-voltage Zn-graphite battery with a non-zinc ion single-salt electrolyte has been developed, achieving high energy density and long-term cycling performance.