Lithium battery enhanced by the combination of in-situ generated poly(ionic liquid) systems and TiO₂ nanoparticles

An instant challenge in the development of polymer electrolytes (PEs) for lithium batteries is the trade-off between sacrificing ion transport for improved mechanical properties. Poly(ionic liquid)s (PILs), which have advantages such as good chemical compatibility and electrochemical stability, is expected to lead the progress of next-generation energy technology. Herein, a series of thermally cured PEs featuring cross-linked ionic networks are fabricated via solvent-less, in-situ polymerization and introduced for rechargeable lithium batteries. To further enhance the battery performance, titanium dioxide nanoparticles (TiO₂ NPs) are dispersed into the component to prepare composite polymer electrolytes (CPEs). Room-temperature ionic conductivity of around 1.97 × 10⁻⁴ S cm⁻¹ is achieved from the sample with 0.5 wt % of TiO₂ addition (CPE-8), which is significantly higher than that of the sample (PE-8) without TiO₂ (1.51 × 10⁻⁴ S cm⁻¹). The qualified thermal property and mechanical strength, enhanced stability against lithium metal, and dendrite suppression guarantee the satisfactory prospects of CPE-8 for development in lithium batteries. The specific discharge capacity of the LiFePO₄/Li cell with the CPE-8 is 149 mAh g⁻¹, and 90% of the value is maintained after 140 cycles at 0.2 C under 25 °C. These advancements are attributed to the synergistic effects of in-situ cross-linked PIL networks and TiO₂ NPs, representing a simple and effective approach towards realizing new CPE for high-performance lithium batteries.