Enhancing performance in all-solid-state lithium batteries with tape cast sandwich-like flexible composite solid electrolyte membranes

All-solid-state lithium batteries (ASSLBs) are considered to be the next generation of the most promising lithium battery technology due to their energy density, safety and stability. Nevertheless, the solid-state electrolyte (SSE), a critical element in ASSLBs, encounters notable obstacles like limited ionic conductivity and elevated interfacial impedance. A sandwich like composite solid electrolyte is proposed to address the above issues. This design features a ceramic-rich (CR) solid electrolyte membrane sandwiched between two polymer-rich (PR) solid electrolyte membranes (named PR-CR-PR). The CR membrane offers mechanical strength, preventing lithium dendrites from penetrating, while the PR membranes enhance interfacial contact with the electrodes. The PR-CR-PR electrolyte not only enhances the stability of Li metal, enabling stable cycle for over 500 h, but also extends the electrochemical window to 6.17 V. Electrochemical results show that the LiFePO 4 /PR-CR-PR/Li battery achieves a specific capacity of 161.97 mAh g −1 at 0.2 C. The battery still maintains a high discharge specific capacity of 147.72 mAh g −1 and a capacity retention rate of 91.2 % after 500 cycles. This study demonstrates a promising strategy to prepare low-cost and highly stable electrolytes using a multilayer design for further mass production of high energy density ASSLBs.