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

Abstract

A Zn-graphite battery with high working voltage and long cycling life was fabricated based on LiPF 6 single-salt electrolyte. The working mechanism and electrochemical performance were investigated. • A high-voltage ZGB based on LiPF 6 single-salt in EMC/TMS electrolyte was constructed. • Zn 2+ was found to be dissolved in the electrolyte during resting and discharging. • The ZGB achieved long-term cyclability and high energy density over 1.0–3.1 V. 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 LiPF 6 in carbonate solvent) is developed. Moreover, we surprisingly found that Zn 2+ is dissolved in the LiPF 6 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 over 1200 cycles at 3C 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.