Dual N-modification enables high-performance Solid-State Li metal batteries with Li5.5PS4.5Cl1.5

All-solid-state lithium batteries (ASSLIBs) have received a lot of attention due to their excellent safety and high energy density, making them a potential alternative to traditional liquid lithium-ion batteries. However, the growth of lithium dendrites within sulfide solid electrolytes is a major challenge in realizing its full potential. Here, a new strategy of modifying the bare Li metal anode surface with a layer of Li3N and introducing N-dopants into the Li5.5PS4.5Cl1.5 electrolyte structure is designed. Such dual N-modification prevents the growth of lithium dendrite, particularly at high current densities during the lithium plating/stripping processes. The dense Li3N interfacial layer induces uniform deposition of lithium ions and optimizes their transport across the interface. When Li dendrites penetrate the interlayer, they are consumed by the N-modified Li5.7PS4.3N0.2Cl1.5 electrolyte, further forming high interfacial energy Li3N to prevent further growth of lithium dendrites. The effectiveness of this strategy has been demonstrated in both lithium symmetric batteries and all-solid-state lithium metal batteries (ASSLMBs). Symmetrical batteries exhibit a stable cycle duration of 400 h at different current densities (0.2 ∼ 1.0 mA cm−2). The corresponding battery consisting of the bare NCM622 cathode, Li5.7PS4.3N0.2Cl1.5 electrolyte, and Li3N-coated Li metal anode delivers a high initial discharge capacity of 183.1 mAh/g at 0.1C and maintains a discharge capacity of 163.4 mAh/g after 50 cycles. The dual N-modification strategy on both bare lithium metal anode and solid electrolytes can significantly enhance the lithium metal compatibility, providing the possibility to construct ASSLMB with superior electrochemical performances.