Overcoming The Low Initial Coulombic Efficiency of Si Anodes Through Prelithiation in All-solid-state Batteries

All-solid-state batteries using Si as the anode have shown promising performance without continual solid-electrolyte interface (SEI) growth. However, the low initial Coulombic efficiency (ICE) of Si limits their energy density. In this work, a prelithiation strategy was adopted to improve the ICE and conductivity of Si all-solid-state cells. Lithiated Si anodes were examined in symmetric-, half-, and full-cell configurations to understand the cell-level improvement. A full cell comprising a Li1Si anode achieved over 95% of ICE when paired with a lithium cobalt oxide (LCO) cathode. Additionally, a comparison of cells containing either a lithium nickel manganese cobalt oxide (NCM) or LCO cathode paired with either Si or LixSi at the anode revealed performance improvements with Si prelithiation only in anode-limited cases. Rate and long-term cycling capabilities were evaluated for Si- and Li1Si-containing cells, showing higher discharge capacities at all rates for Li1Si than Si. With Li1Si, 73.8% capacity retention was achieved after 1000 cycles, a 15% improvement when compared to a pure Si anode. With Li1Si, a high areal capacity of up to 10 mAh cm-2 was attained using a dry-processed LCO cathode film, suggesting that the prelithiation method may be suitable for high loading next-generation all-solid-state batteries.