Long-Lasting Solid Electrolyte Interphase for Stable Li-Metal Batteries

Abstract

Lithium batteries composed of Li-metal anodes, ester-based electrolytes, and Ni-rich Li[NixCoyMn1-x-y]O-2 (NCM) cathodes have emerged as potential candidates for next-generation energy storage technologies. However, identifying suitable electrolytes, which are highly compatible with NCM cathodes and simultaneously form stable solid electrolyte interphase (SEI) layers on Li-metal anode surfaces, is a significant challenge. Herein, we introduce a new electrolyte additive of P2S5 -saturated CS2 (PSC) solution (1 wt.%) to modify the ester-based electrolyte, and then, an ionically conductive SEI can be generated to stabilize the Li-metal significantly. We discover that the P2S5 can be solvated by the CS2, in which the solution can facilitate the in situ formation of a stable SEI containing inorganic Li-P-S compounds (Li-ion conductors, likely Li3PS4), enabling the dendrite-free and highly reversible Li-metal anode. Then, a practical battery, configured by a Li-metal anode, PSC-modified electrolyte, and a Li[Ni0.73Co0.10Mn0.15Al0.02]O-2 cathode, demonstrates high capacity, cycling stability, and Coulombic efficiency over 1500 cycles.