Preparation and Characterization of TiO2-Reinforced TPU/PDMS Composite Gel Polymer Electrolyte for Lithium Batteries

To further enhance the comprehensive performance of polymer electrolytes, this study prepares a ternary composite gel polymer electrolyte (CGPE) based on TiO 2 /thermoplastic polyurethane (TPU)/polydimethylsiloxane (PDMS) via a solution casting method, systematically investigating the influence of TiO 2 content on the properties of CGPE. Structural characterization reveals that TiO 2 nanoparticles achieve a “dual crystalline phase regulation” mechanism by inhibiting polymer crystallization and introducing anatase crystal phase. When the TiO 2 content is 9 wt%, the CGPE exhibits optimal performance: ionic conductivity reaches 4.59 × 10 −3 S/cm, an 81.5% increase compared to the pure polymer matrix; tensile strength is 9.61 MPa, elongation at break is 449%; lithium ion transference number is 0.78; and the electrochemical stability window is 0–5.0 V versus Li/Li + . The assembled LiFePO 4 /Li half-cell demonstrates a rate capability of 87.4% when the current density increases from 0.1 to 1 C, with 99.2% retention after 100 cycles. The results confirm the application potential of TiO 2 -reinforced CGPE in high-safety lithium-ion batteries.