Quasi-Double-Layer Solid Electrolyte with Adjustable Interphases Enabling High-Voltage Solid-State Batteries.

Increasing the energy density and long-term cycling stability of lithium-ion batteries necessitates the stability of electrolytes under high/low voltage application and stable electrode/electrolyte interfacial contact. However, neither single polymer nor liquid electrolyte can realize it due to their limited internal energy gap, which cannot avoid lithium metal deposition and electrolyte oxidation simultaneously. Herein, a novel type quasi-double-layer composite polymer electrolytes (QDL-CPEs) are proposed by using the plasticizers with high oxidation stability (propylene carbonate) and high reduction stability (diethylene glycol dimethyl ether) in the polyvinylidene fluoride (PVDF) based electrolyte composites. In-situ polymerization of propylene carbonate can function as the cathode electrolyte interface (CEI) film, which can enhance the antioxidant ability. The nucleophilic substitution reaction between diethylene glycol dimethyl ether and PVDF increases the reduction stability of the electrolyte on the anodic side, without the formation of lithium dendrite. The QDL-CPEs has high ionic conductivity, enhanced electrochemical reaction window, adjustable electrode/electrolyte interphases, and no additional electrolyte-electrolyte interfacial resistance. Thus, this ingenious design of QDL-CPEs improve the cycling performances of the NCM811//QDL-CPEs//hard carbon full cell at room temperature, paving a new way for designing solid-state battery systems accessible for practical applications. This article is protected by copyright. All rights reserved.