High Diffusivity Lithium Intermetallic in Two-Phase Alloy Negative Electrode for Solid-State Batteries

Alloying offers a promising solution to the challenges of metallic lithium anodes in solid-state lithium batteries. Here, we explore a two-phase lithium alloy system, comprising lithium–intermetallic and lithium–metallic phases. Experimental measurements, supported by computational modelling, quantify the influence of both microstructural features and intermetallic properties on electrochemical performance. We demonstrate that the rapid lithium diffusivity in the Li₃Bi intermetallic, when combined with a lithium–magnesium matrix, provides continuous fast lithium diffusion pathways that alleviate typical transport limitations during discharge. This work highlights the potential of scalable metallurgical approaches for optimising electrode architecture in solid-state battery systems.