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

摘要

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 Zn^(2+) 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 ~100% for over1200 cycles at 3 C and high Coulombic efficiency of ~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.