A Tailored Interface Design for Anode‐Free Solid‐State Batteries

Abstract Anode‐free solid‐state batteries (AFSSBs) are considered to be one of the most promising high‐safety and high‐energy storage systems. However, low Coulombic efficiency stemming from severe deterioration on solid electrolyte/current collector (Cu foil) interface and undesirable Li dendrite growth impede their practical application, especially when rigid garnet electrolyte is used. Here, an interfacial engineering strategy between garnet electrolyte and Cu foil is introduced for stable and highly efficient AFSSBs. By utilizing the high Li ion conductivity of LiC₆ layer, interfacial self‐adaption ability arising from ductile lithiated polyacrylic acid polymer layer and regulated Li deposition via Li‐Ag alloying reaction, the garnet‐based AFSSB delivers a stable long‐term operation. Additionally, when combined with a commercial LiCoO₂ cathode (3.1 mAh cm⁻²), the cell also exhibits an outstanding capacity retention due to the tailored interface design. The strategies for novel AFSSBs architecture thus offer an alternative route to design next‐generation batteries with high safety and high density.