In-situ generated Li3N/Li-Al alloy in reduced graphene oxide framework optimizing ultra-thin lithium metal electrode for solid-state batteries

• A 40 µm thick composite lithium anode is proposed. • In-situ generated Li 3 N (inside electrode) and Li-Al alloy nucleation sites mitigate the dendrite growth. • The Li 3 N-modified solid electrolyte interphase (SEI) enhances the interfacial stability. • The solid-state symmetric cell cycles over 2100 h at 0.2 mA cm −2 /0.2 mAh cm −2 with a low voltage hysteresis (<10 mV). Optimization of lithium metal anode is a pivotal part in facilitating the evolution of next-generation high energy density solid-state lithium metal batteries (LMBs). However, the practical application of lithium anode in solid-state LMBs is limited by uncontrollable dendrite growth and the poor interfacial contact with solid electrolyte. Herein, a 40 µm thin lithium composite anode based on the AlN-embedded reduced graphene oxide (rGO) scaffold synthesized via one-step molten lithium infusion is proposed. The resulting lithiophilic Li-Al alloy and high ion-conductive Li 3 N in situ constructed the lithium ion diffusing highways inside electrode, enabling a well-oriented Li deposition and effectively inhibiting the dendrite growth. Combined with in-situ polymerization and Li 3 N-modified solid electrolyte interphase (SEI), the composite anodes can prolong the lifespan of symmetric cell to 2100 h at 0.2 mA cm −2 /0.2 mAh cm −2 in carbonate-based solid polymer electrolytes. Moreover, LAG||LiFePO 4 full cells also excelled in cycling capability and rate performance. This modified electrode offers a promising synergistic solution for designing high-performance solid-state LMBs.