A fast ionic transport copolymeric network for stable quasi-solid lithium metal battery

Solid-state lithium (Li) metal batteries overwhelm the lithium-ion batteries by harvesting high energy from Li metal anode with ultrahigh capacities and gaining excellent safety from solid electrolytes. However, the uncontrollable solvents in solid electrolytes usually aggravate poor interfacial contact with lithium metal anode and deteriorate Li+ pathways. Here a copolymeric network-structured ion conductor by rationally integrating cellulose nanofibril as a two-in-one functional material is employed to anchor the solvent. Taking advantages of tightly anchoring of cellulose nanofibril to solvent, the as-constructed quasi-solid polymer-based electrolyte offers rapid Li+ transport channels and realizes effective Li-dendrite suppression, which enables high ionic conductivity of 1.93 × 10−3 S cm−1 at room temperature, long-term Li plating/stripping over 1900 h, and high capacity retention of 99%. This work provides a fresh strategy for creating solid electrolytes that meet both high ionic conductivity and interfacial stability requirements for practical solid-state lithium metal battery.