A Stable Matrix Assisting Highly Compatible and Maintainable Lithium‐Garnet Interface for Solid‐State Batteries

Abstract Solid‐state Li metal batteries (SSLMBs) are attractive due to their capability to simultaneously offer high energy density and high‐level safety when combining Li metal anodes, solid‐state electrolytes (SSEs), and high‐voltage cathodes together. However, SSLMBs may well incur short circuits caused by Li dendrites penetrations, which mainly originate from the instability and poor contact between Li metal and SSEs. Herein, by taking full advantage of the reaction products of Li and Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 (LATP), a lithium‐LATP composite anode (Li‐LATP) is obtained, in which a stable matrix is formed to enhance the contact between Li and the garnet‐type SSEs, alleviating the volume change and preserving an intact interface during the charge/discharge process. Consequently, the Li‐LATP/garnet/Li‐LATP symmetric cell displays a fairly low interfacial resistance of 6 Ω cm 2 and stable cycling performance for over 2500 h with a low overpotential. Furthermore, the LiCoO 2 /garnet/Li‐LATP full cell also shows a high discharge capacity of 159 mAh g −1 and great cycling performance.