Built-in superionic conductive phases enabling dendrite-free, long lifespan and high specific capacity composite lithium for stable solid-state lithium batteries

Solid-state lithium metal batteries (SSLMBs) are considered as one of the most promising energy storage systems because of their high-energy density and intrinsic good safety. However, the practical application of SSLMBs is hindered by the huge interfacial resistance and growth of detrimental Li dendrites. To solve these obstacles, a composite lithium anode (CLA) with built-in well-dispersed ionic conductive Li 3 N and LiN x O y species is specially designed and prepared, which on one hand greatly promote the intrinsic ionic diffusion capability of the bulk lithium anode, and on the other hand simultaneously improve the wettability of the anode towards solid-state electrolyte (SSE), construct a robust and high ionic conductive solid-state interface and effectively enhance the chemical contact of Li/SSE as demonstrated by density functional theory (DFT) calculations. A top-level area specific capacity (1.5 mA h cm −2 , 0.5 mA cm −2 ) and ultra-high critical current density (1.4 mA cm −2 ) are achieved for all-solid-state symmetric cells at room temperature. The full SSLMB coupling with the CLA and commercial LiFePO 4 (LFP) cathode achieves excellent cycling performance as long as 500 cycles with a capacity retention of 80.0% and high-rate capability of 2.0 C. Even under high voltage (4.3 V) conditions, the solid-state full cell matched with LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) could stably be cycled more than 115 times with a retention of 80.0%. The findings provide a new composite anode strategy for high-performance solid-state Li metal batteries. A composite lithium anode with built-in superionic conductive Li 3 N and LiN x O y phases can greatly promote the ionic diffusion capability of bulk lithium, simultaneously improve the wettability, and construct a robust ionic conductive interface.