Constructing solid electrode-electrolyte interfaces in high-voltage Li|LiCoO2 batteries under dual-additive electrolyte synergistic effect

Abstract

High-voltage lithium metal batteries (LMBs) using lithium cobalt oxide (LCO) as cathode can deliver the coveted high energy density, but come at a sacrifice of cycling stability due to the unstable electrode/electrolyte interphase and LCO instability at high voltage. Here, we demonstrate a modified conventional carbonate-based electrolyte for Li|LCO LMBs by simply introducing vinylene carbonate (VC) and KBF4 as the organic/inorganic dual-additive. In a synergistic way, the dual-additive is capable of helping to generate thin and dense cathode electrolyte interphase (CEI) on LCO, effectively alleviating the drastic electrolyte decompositions at high voltage, as well as the irreversible transition from O3 to H1-3 phase, Co dissolving, and structure collapse of LCO. Meanwhile, the corrosion layer on Li anode is also mitigated due to the dual-additive-derived solid electrolyte interphase (SEI) film. Based on the dual-additive electrolyte, the assembled 4.6 V Li|LCO LMB achieves promising long-term cycling performance with a capacity retention of 91.1% after 300 cycles at 1 C (1 C = 274 mA g−1). The simple and effective electrolyte engineering strategy can promote the development of high-voltage lithium metal batteries.