A lean-lithium metal anode based on Gr@MgF2 for solid-state batteries

Utilizing thin Li anodes is the key to realizing high-energy-density solid-state lithium metal batteries (SSLMBs). However, the practical implementation of thin Li anodes is significantly challenged by the inevitable formation of lithium dendrites, as well as the lithium depletion caused by interfacial side reactions. To address this, we propose a lumped Li-Gr@MgF₂ (LGMF) anode comprised of lithiated MgF₂-coated graphite, which precisely reconstructs the lean-lithium metal anode through bottom-up integration. Finely optimized electrode units of LiC₆-LiMg/LiF possess lithiophilic Li-Mg alloy and high-interface-energy LiF interfacial modification, which regulate the lithium-ion flux and effectively suppress dendrite growth. Assembling electrode units collaboratively establishes the ion-electron percolating network within the LGMF, fully activating the entire anode. The optimized LGMF anodes extend the longevity of carbonate-based quasi-solid-state symmetric cells to 2400 h at 0.2 mA cm⁻²/0.2 mAh cm⁻², even under limited lithium conditions. LiFePO₄ full cells utilizing LGMF anodes exhibit steady galvanostatic cycling over 400 cycles, attaining a notable capacity retention of 95.5 % at 0.5 C. Meanwhile, the LGMF||LiNi_0.83Co_0.12Mn_0.05O₂ cells demonstrate enhanced rate capability and prolonged electrochemical lifespan. This strategy offers practical insight for lean-lithium metal anode engineering toward high-energy-density SSLMBs.