Enabling reliable lithium metal batteries by a bifunctional anionic electrolyte additive

Lithium metal has been considered as an attractive anode for high energy density lithium battery because of high specific capacity and the lowest redox potential. However, the growth of Li dendrites during cycling has hindered the practical application of Li metal battery (LMB). Herein, TTFEB is adopted as a bifunctional electrolyte additive to improve the performance of Li metal anode, which is beneficial for the surface chemistry of anode and the property of the electrolyte. A LiF-rich SEI layer and enhanced Li+ migration in electrolyte can be achieved with 2% TTFEB, which result in uniform Li deposition without uncontrollable Li dendrites. With controlled Li deposition in TTFEB-containing electrolyte, a significantly improved Coulombic efficiency (~ 96%) in Li|Cu cell, long lifetime (over 1000 h), and weak polarization in Li|Li cell can be obtained. Moreover, excellent cycling performance and rate capability of Li|LiFePO4 cells with TTFEB are also presented in this work. Our strategy provides new insights on the diverse function of electrolyte additives for rechargeable LMB.