Single-Ion Conducting Multi-block Copolymer Electrolyte for Lithium-Metal Batteries with High Mass Loading NCM811 Cathodes

Abstract

Lithium-metal batteries comprising a single-ion conducting polymer electrolyte and a nickel-rich LiNi_1-x-yCo_xMn_yO₂ (NCM) positive electrode (cathode) potentially offer very high energy density and great safety. However, such cell chemistry is very demanding concerning the required interfacial stability of the polymer electrolyte, and the realization of high mass loading cathodes remains a great challenge. Herein, the development of a new single-ion conducting multi-block copolymer electrolyte including trifluoromethyl groups in the ionophilic block is reported. After ethylene carbonate (EC) is incorporated into the self-standing and easily processable polymer membranes, high ionic conductivity along with very high limiting current density and suitable anodic stability are obtained. These enable stable cycling of Li∥NCM₈₁₁ cells─also at high C rates (up to 5C) and active material mass loadings of the NCM₈₁₁ cathode of >10 mg cm^–2, which are both key steps toward the potential commercialization of this class of electrolytes.