Prelithiation of Alloy Anodes via Roll Pressing for Solid-State Batteries

Solid-state batteries with alloy-type negative electrodes can feature enhanced energy density and safety compared to conventional Li-ion batteries. However, diffusional Li trapping within Li alloys often causes low initial Coulombic efficiency and leads to capacity loss with cycling. Here, a general roll-pressing prelithiation method compatible with a variety of alloy-type negative electrodes (silicon, aluminum, tin, and multi-phase alloys) is introduced, which is shown to improve performance in solid-state batteries. By warm-rolling lithium foil of controlled thickness with various alloy-type electrodes, both slurry-cast and foil-type electrodes can be uniformly prelithiated via direct chemical reaction. The prelithiated electrodes exhibit enhanced specific capacity and extended cycle life in batteries with Li₆PS₅Cl solid-state electrolyte. Prelithiated multi-phase foil electrodes with a tailored interface are shown to exhibit superior cycling stability down to 2 MPa stack pressure. This prelithiation technique offers a pathway to overcome intrinsic challenges in alloy anodes for solid-state batteries.