Borohydride Solid-State Electrolytes: Ion Transport Mechanisms and Modifications

The ongoing global transition toward higher energy density and enhanced safety in energy systems has positioned all-solid-state lithium batteries as a pivotal solution to current energy storage limitations, owing to their intrinsic safety characteristics and lithium metal anode compatibility. Borohydride-based solid-state electrolytes demonstrate exceptional performance characteristics, including high ionic conductivity exceeding 10-3 S/cm at room temperature, broad electrochemical stability windows, and structurally tunable [BH4] anion frameworks. This paper systematically describes the structural features of borohydride solid-state electrolyte and analyzes the conductive mechanism of this electrolyte from the point of view of defect chemistry; At the same time, this paper not only nearly reviews the progress of modification of borohydride solid-state electrolytes in the direction of solid solution and elemental doping in recent years, but also reveals the technical challenges of borohydride solid-state electrolytes in their own performance and scale-up preparation. Based on this, this paper looks at future research directions for borohydride solid-state electrolytes in terms of material properties, interface engineering and process optimization.