Reactive strontium nitride Additive: Constructing ion/electronic conductive paths for garnet-based solid-state lithium metal batteries

Abstract

Solid-state lithium metal batteries (SSLMBs) using the garnet electrolyte Li6.4La3Zr1.4Ta0.6O12 (LLZTO) offer high safety and energy density compared to liquid organic electrolyte lithium-ion batteries. However, the interfacial electrochemical stabilization of Li metal anode with LLZTO leads to problems such as high interfacial resistance and Li dendrite growth, which hinders the wide application of SSLMBs. In this work, a multifunctional Li-Sr-N composite anode by mixing molten Li with Sr3N2 is constructed, in which the reactive wetting of in situ-formed Li3N achieves intimate interfacial contact, and the ionic/electronic conductive paths created by Li-Sr alloys and Li3N effectively homogenise Li deposition and suppress Li dendrites. The interfacial resistance is reduced to 40.42 Ω cm2, and the symmetric cell is stably cycled for 5500 h and 600 h at current densities of 0.1mA cm−2 and 0.4 mA cm−2, respectively, and the full cell of Li-Sr-N|LLZTO|LiFePO4 could be stably cycled for 200 cycles at 0.5C. The preparation of composite anodes using Sr3N2 as an additive may be a new strategy for producing of garnet-based SSLMBs with outstanding energy density and safety performance.