<p>The all-solid-state lithium metal battery (ASSLMB) has drawn much attention for its high energy density and excellent safety, and is considered a promising candidate for next generation battery systems. However, the typical all-solid-state electrolyte based on polyethylene oxide (PEO) still suffer from low ion conductivity and Li⁺ transfer number, limiting their practical application. Here, we fabricated a composite all-solid-state electrolyte by intercalating layered double hydroxides into a phenolic resin (PR)-modified PEO-based all-solid-state electrolyte, in which PEO and PR can form a self-supporting structure through hydrogen bonding interactions, lowering the crystallinity of PEO, meanwhile, the layered double hydroxides were delaminated by the Li salts induced from the strong electrostatic interaction, promoting the dissociation of Li salts and increasing the Li⁺ transference number. Thus, the as-prepared solid electrolyte displays high ionic conductivity of 1.8 × 10^− 4 S cm^− 1 and Li⁺ transference number of 0.74. The Li || Li symmetrical cells with such a solid electrolyte exhibit a small voltage hysteresis at 0.1&#xa0;mA cm^− 2 after 1000&#xa0;h under room temperature. Full cells with LiFePO₄ cathode deliver a high discharge capacity of 152.6 mAh g^− 1 and capacity retention at 0.1&#xa0;C under room temperature. This work offers a promising route to the practical application of ASSLMB.</p> TOC <p>A composite all-solid-state electrolyte is achieved by intercalating layered double hydroxides into a phenolic resin (PR)-modified PEO-based electrolyte, resulting in extremely high ionic conductivity of 1.8×10^-4 S cm^-1 and Li⁺ transference number of 0.74</p> <p></p>