Integrated Structure of Cathode and Double-Layer Electrolyte for Highly Stable and Dendrite-Free All-Solid-State Li-Metal Batteries

All-solid-state batteries have become the most potential next-generation energy-storage devices. However, it is quite difficult to simultaneously achieve a single solid-state electrolytes (SSEs) layer with both dendrite-free Li metal plating and low interfacial resistance between the cathode and SSEs. Herein, an integrated structure of cathode and double-layer solid electrolyte membrane (IS-CDL) is designed, which greatly improves the interfacial contact and suppresses the Li dendrite growth. The first "polymer in ceramic" solid electrolyte layer (SL1) consists of 80 wt % Li_1.4Al_0.4Ti_1.6(PO₄)₃ (LATP) nanoparticles and 20 wt % polyethylene oxide (PEO), and the second polymer electrolyte layer is PEO-based solid electrolyte layer (SL2). The SL1 with high mechanical properties can hinder the growth of Li dendrites and reduce the interfacial resistance with the cathode. The SL2 can inhibit the side reaction between the Li metal and LATP. The Li symmetric cells with sandwich-type hierarchical electrolyte (SL2/SL1/SL2) can stably cycle over 3200 h at 0.1 mA cm^-2 at 45 °C. The obtained all-solid-state LiFePO₄-IS-CDL/Li batteries present a capacity of 142.6 mA h g^-1 at 45 °C with the capacity retention of 91.7% after 100 cycles, and all-solid-state NCM811-IS-CDL/Li batteries deliver a specific capacity of 175.5 mA h g^-1 at 60 °C. This work proposes an effective strategy to fabricate all-solid-state lithium batteries with high electrochemical performance.