Incorporating lithium magnesium silicate into PVDF-HFP based solid electrolyte to achieve advanced solid-state lithium-ion batteries

Polymer electrolytes possess good flexibility and processability, and have wide application prospects in the field of battery. However, polymer electrolytes have the disadvantages of low ionic conductivity, narrow electrochemical window and poor mechanical properties. Herein, we designed a PVDF-HFP based composite electrolyte filled with lithium magnesium silicate. The addition of lithium magnesium silicate can disrupt the ordered arrangement of polymer chain segments, promote the dissociation of lithium salts, increase the content of [NMP-Li+], reduce the gap on the surface of PVDF-HFP electrolyte membrane, inhibit the migration of anions and improve the electrochemical stability of the electrolyte membrane. To improve the mechanical properties of the electrolyte membrane, polyethylene membrane with excellent mechanical property was added into the electrolyte membrane. The modified PVDF-HFP based polymer composite electrolyte membrane has high ionic conductivity (2.56 × 10−4 S·cm−1) under room temperature and high lithium ion migration number (0.41). Due to its good lithium ion transmission ability, the oxidation potential (4.8 V) and the ability to restrain lithium dendrite growth of the modified PVDF-HFP based composite electrolyte have been effectively boosted. The whole battery assembled with this electrolyte membrane and NCM622 can stably cycle for 50 cycles at 0.5 C (capacity retention rate is 89.6%).