Tuning hybrid liquid/solid electrolytes by lowering Li salt concentration for lithium batteries

Hybrid liquid/solid electrolytes (HLSEs) consisting of conventional organic liquid electrolyte (LE), polyacrylonitrile (PAN), and ceramic lithium ion conductor Li1.5Al0.5Ge1.5(PO4)3 (LAGP) are proposed and investigated. The HLSE has a high ionic conductivity of over 2.25 × 10−3 S/cm at 25 °C, and an extended electrochemical window of up to 4.8 V versus Li/Li+. The Li|HLSE|Li symmetric cells and Li|HLSE|LiFePO4 cells exhibit small interfacial area specific resistances (ASRs) comparable to that of LE while much smaller than that of ceramic LAGP electrolyte, and excellent performance at room temperature. Bis(trifluoromethane sulfonimide) salt in HLSE significantly affects the properties and electrochemical behaviors. Side reactions can be effectively suppressed by lowering the concentration of Li salt. It is a feasible strategy for pursuing the high energy density batteries with higher safety.