Ceramic-Doped in Cross-Linked Solid Polymer Electrolyte for Solid-State Batteries

Abstract

Replacing liquid electrolytes with solid-state Li-ion conductors is one way to achieve safe rechargeable batteries with high energy density. Semi-interpenetrating polymer network (s-IPN) was synthesized from the mixture of poly(propylene carbonate), poly(ethylene glycol) methyl ether acrylate, poly(ethylene glycol) diacrylate (PEGDA), and lithium bis(trifluoromethane)sulfonamide salt via one-pot thermal curing method. The crosslinker PEGDA content and salt concentration were optimized and the best result was abtained at a molar ratio of EO:Li ∼ 14:1. The electrolyte with higher salt concentration had lower ionic conductivity, consistent with higher glass transition temperature of poly(ethylene glycol) chain. Differential scanning calorimetry has shown a low degree of crystallinity when lithium lanthanum zirconate doped tantalum (LLZTO) was added to the s- IPN electrolyte which corresponds to an increase in ionic conductivity, 4.5 x 10-4 S/cm at 40°C. The resulting composite polymer electrolyte (CPE) showed high electrochemical stability up to 5.5 V. Lithium plating and stripping at 0.1 mA/cm2 at room temperature revealed a stable Li/electrolyte interface and no dendrite formation. Cycling performance of a full solid-state cell made with the CPE using LiFePO4 as the cathode will be discussed. Figure 1