Lowering the operating temperature of PEO-based solid-state lithium batteries via inorganic hybridization

Employing the solid polymer electrolyte (SPE) instead of traditional liquid electrolyte is an effective way to develop high safety and high-energy density solid-state lithium batteries. Herein, for the first time, the Ni 3 B 2 O 3 (NBO) nanorods are incorporated into polyethylene oxide (PEO)-based SPE. Particularly, the optimized NBO-embedded SPE shows a high ionic conductivity of 8.5 × 10 −5 S cm −1 at 30 °C, lowering the operating temperature of PEO-based SPE substantially. The corresponding LiFePO 4 /Li battery demonstrates a high discharge capacity of 154 mAh g −1 after 80 cycles at 0.2 C under 30 °C, with favorable capacity retention of 97.5%. The remarkable properties are attributed to the high ionic conductivity of modified SPE at ambient temperature, which is resulted from the decreased crystallinity and melting transition point, increased movement of PEO chain, and promotion of lithium salt dissociation, as well as the formation of the lithium ion migrating pathway on the interface between PEO and NBO nanorods.