Interface\nEngineering of Aluminum Foil Anode for Solid-State\nLithium-Ion Batteries under Extreme Conditions

Alloy foil anodes have garnered significant attention\nbecause of\ntheir compelling metallic characteristics and high specific capacities,\nwhile solid-state electrolytes present opportunities to enhance their\nreversibility. However, the interface and bulk degradation during\ncycling pose challenges for achieving low-pressure and high-performance\nsolid-state batteries. In this study, we engineered a nonintrusive\nsolid-state electrolyte rich in fluorine and boron and developed aluminum\nmetal foils featuring a densely structured and highly lithiated interface,\neffectively suppressing interfacial contact loss and promoting the\nformation of a stable interfacial layer rich in fluorine and boron,\nhelping to minimize fluctuations in Coulombic efficiency. With high\nareal cathode capacities (∼2.5 mAh cm<sup>–2</sup>),\nthe low-pressure solid-state battery exhibited stable cycling performance\nfor over 140 cycles, achieving an average Coulombic efficiency of\n99.86%. Our findings provide a solid framework for designing durable\nelectrolyte/anode interfaces in ambient-pressure, intrinsically safe\nalloy-foil-based solid-state batteries.