Suppressing Li voids in all-solid-state lithium metal batteries through Li diffusion regulation

Abstract

The application of all-solid-state lithium metal batteries (ASSLMBs) is hampered by the dynamic deterioration of solid-solid contacts. Anodic degradation is primarily attributed to the accumulation of lithium (Li) voids due to the limited Li diffusion abilities of the anodes. Here, a ternary composite Li anode is introduced by comprising carbon materials embedded within the Li-magnesium substrate. This design effectively suppresses the Li void-induced dynamic deterioration of interfacial contact during continuous cycling. The enhanced Li diffusion pathway with accelerated diffusion rate in bulk anode aids in maintaining contact post-Li stripping, therefore mitigating interface damage caused by Li void formation. The ternary composite anode affords an areal capacity of 14.2 mAh cm⁻² with Li utilization rate of 85%. Cooperated with LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) cathodes, the full cells exhibit long-term stability of >300 cycles under room temperature. These findings provide an effective strategy to construct conformal interfaces for high-capacity and long-life ASSLMBs.