A Nondeposition Solid-Solution Li Alloy Anode for Solid-State Batteries

Lithium-based metal has been regarded as the most promising anode for high-energy all-solid-state lithium metal batteries (ASLMBs). However, its uncontrollable deposition/dissolution mechanism causes fast cell failure due to severe dendritic growth, poor interfacial stability, and rapid mechanical degradation. Herein, a nondeposition Li alloy was developed via a thermo-mechanical coupled synthesis with flexible processability and capacity customizability. A single-phase LiGa alloy with dual electronic/ionic conductivity and a low working potential (0.2 V) was obtained that exhibited a reversible solid-solution alloy/dealloy mechanism, thus fundamentally avoiding the deposition of highly active metallic Li at the electrolyte/anode interface. With prominent merits of both nondeposition mechanism and electronic/ionic conductivity, the LiGa-based symmetric cell with Li 6 PS 5 Cl enables a radically extended lifespan from 450 to 6000 h and an ultrahigh current density exceeding 7.1 mA·cm –2 . Besides, this nondeposition-type Li alloy allows high stability toward various solid electrolytes, including poly(ethylene oxide), Li 3 InCl 6, and Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3, providing new choices for high-energy ASLMBs.