Enhanced air stability and interface compatibility in Nb-O-doped Cl-rich Li-argyrodites for all-solid-state Li metal batteries

Cl-rich Li-argyrodites are one type of sulfide solid electrolytes (SSEs) with a high ionic conductivity and suitable mechanical properties for practical application. However, their tolerance against moisture in air and compatibility with metallic Li need further improvements. Here, we demonstrate that Nb-O dual-doping can be a good strategy for advanced Cl-rich Li-argyrodite SSEs, prepared by high energy ball milling and annealing method. Our results show that the Nb-O co-doping enhances the interface compatibility towards metallic Li and improves the moisture resistance, while maintains a fast ion transport. The Nb-O incorporation improves the Young's modulus and mitigates the side reaction of Li-argyrodite with Li. The doping-optimized sample demonstrates a high critical current density of 2.28 mA cm⁻² and a long-term Li plating/stripping stability under a relatively high current density (1 mA cm⁻²) for nearly 3000 cycles. Notably, the corresponding all-solid-state lithium batteries (ASSLBs), using a Li metal electrode, can maintain a superior cycling stability for over 1000 cycles at 1 C.