An Interdigitated Li-Solid Polymer Electrolyte Framework for Interfacial Stable All-Solid-State Batteries

All-solid-state lithium metal batteries are prominent candidates for next-generation batteries with high energy density and low safety risks. However, the traditional planar contact between Li metal and solid-state electrolytes (SSEs) exhibits substantive void formation and large interfacial morphological fluctuation, causing poor interfacial stability. Here, an interdigitated Li-solid polymer electrolyte framework (I-Li@SPE), a pioneering demonstration of 3D interface in polymer-based all-solid-state batteries, is designed, transferring the Li-SSE interfacial contact from planar to 3D for enhanced interfacial integrity. A smooth and intact 3D Li-SSE interfacial contact after repeated cycling that precedes planar Li-SSE contact, is shown. COMSOL simulation indicates I-Li@SPE reduces local current densities by more than 40% and moderates interfacial variation by more than 50%. As a result, I-Li@SPE achieves high critical current density of 1 mA cm⁻², as well as promising high areal capacity cycling of 4 mAh cm⁻² at 0.4 mA cm⁻². This work provides a new structure for Li-SSE composite fabrication and high-capacity solid-state Li batteries.