Stabilizing the electrode–electrolyte interface for high-voltage Li‖LiCoO2 cells using dual electrolyte additives

Abstract

Rechargeable Li‖LiCoO₂ batteries are attractive due to their high energy density. However, the growth of lithium dendrites and the degradation of cathode at high potential hinder their practical application. Herein, we propose an advanced fluorinated carbonate-based electrolyte consisting of trans-4,5-difluoro-1,3-dioxolan-2-one (DFEC) and tri-(trimethylsilyl) phosphite (TMSPi) as dual additives to construct a stable interface on both the anode and cathode. The results show that DFEC can promote the formation of a stable solid-electrolyte-interface (SEI) layer on the lithium anode to inhibit the growth of dendrites. Additionally, TMSPi is conducive to the production of an inorganic-rich cathode–electrolyte interface (CEI) layer on the LiCoO₂ cathode to inhibit the dissolution of cobalt. Finally, the Li‖LiCoO₂ cells with this electrolyte could obtain an initial capacity of 211.6 mAh g⁻¹ (846.4 Wh kg⁻¹, active substances based on cathodes) at 1C (1C = 274 mA g⁻¹) with a high-capacity retention of 81.6% after 200 cycles at a high upper cut-off voltage of 4.6 V. This work provides valuable insights into the development of electrolytes for high-voltage Li‖LiCoO₂ cells.