Ultrastable Lithium-Ion Batteries Prepared by Introducing γ-LiAlO2 in a Gel Polymer Electrolyte at 50 °C Working Temperature

Poly(vinylidene fluoride) (PVDF) gel polymer electrolytes (GPEs) show great potential for application in lithium-ion batteries (LIBs) due to their outstanding characteristics. However, the inferior thermal stability and low ionic conductivity limit their practical application. Herein, γ-LiAlO2 was synthesized and applied in a polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP)-polybenzimidazole containing an ether bond (OPBI)-polyoxyethylene (PEO) (PHOP-LAO) GPE for improving its thermal stability and ionic conductivity properties. The ionic conductivity of PHOP-LAO is 4.83 mS cm–1, which increased by 210% compared with that of the PHOP sample. It is worth noting that the thermal shrinkage of the PHOP-LAO membrane is greatly reduced (less than 1% at 230 °C for 1 h). PHOP-LAO shows outstanding thermal stability, which is beneficial for the safety of LIBs. When the PHOP-LAO GPE was applied to LIBs with Li1.04Ni1/3Co1/3Mn1/3O2 as a cathode, the LIBs exhibit remarkable and stable cycling performance with a discharge capacity retention rate of 85% after 500 cycles at a 2 C rate and maintain a power capability retention rate of up to 77% of the initial capability at the high rate of 10 C (50 °C). PHOP-LAO thus shows great potential for achieving ultra-stable and safe LIBs in the future.