A Highly-Efficient Composite Separator with Strong Ligand Interaction for High-Temperature Lithium-Ion Batteries

Graphical Hot in, so hot in here ! By incorporating colloidal TiO 2 in PVDF-HFP, a composite separator is fabricated showing a robust micro-structure sustaining high-temperature treatment. LFP/Li batteries based on the PVDF-HFP/colloidal-TiO 2 separator deliver a charge-discharge capacity of 156.9 mAh g −1 (0.1 C) at room temperature and 120.8 mAh g −1 (0.5 C) after annealing batteries at 140 °C for 3 hours with a 99 % capacity retention. A PVDF-HFP/colloidal-TiO 2 composite separator is synthesized for high-temperature lithium-ion batteries. Incorporation of colloidal TiO 2 in the PVDF-HFP matrix forms a highly-uniform composite micro-structure with strong adsorption interactions between TiO 2 and PVDF-HFP due to the presence of citric acid. The strong interactions are giving rise to advantageous mechanical robustness, separator/electrode interface and electrolyte uptake. The separator shows remarkable stability upon thermal treatment at 150 °C. With a high ionic conductivity up to 1.57×10 −3 S cm −1 , the LFP/Li cell with PVDF-HFP/colloidal-TiO 2 composite separator delivers charge-discharge capacities of 156.95 mAh g −1 (0.1 C) at room temperature and 120.8 mAh g −1 (0.5 C) after annealing cells at 140 °C for 3 hours with a 99 % capacity retention after 100 cycles. The PVDF-HFP/colloidal-TiO 2 separator demonstrates promising potentials for practical applications in high-temperature environments.