High-performance polymer electrolyte membrane modified with isocyanate-grafted Ti3+ doped TiO2 nanowires for lithium batteries

Highlights: • The partly crosslinked polymer electrolyte presents a maximum conductivity of 1× 10⁻⁴ S·cm⁻¹ at 30 °C and wide electrochemical window. • The LiFePO₄ Li cell exhibits excellent capacity retention of 91% after 100 cycles. • Satisfactory stability for NCM811 Li high-voltage lithium batteries. The Ti³⁺ doped TiO₂ nanowires were grafted by tolylene-2,4- diisocyanate (TDI) and applied as a modifier for the preparation of organic–inorganic hybrid electrolyte in high performing lithium batteries. The PEO-based polymer electrolyte was optimized at different organic–inorganic ratios and exhibited excellent lithium-ion conductivity of 1 × 10⁻⁴ S·cm⁻¹ at 30 °C when adding 8% TDI-TiO₂ nanowires, outstanding electrochemical stability with a wide electrochemical window up to 5.5 V at 60 °C and a high lithium-ion transport number of 0.36. The LiFePO₄ PTTNW8% Li cells deliver excellent rate capability and cycling performance, with a high initial discharge capacity up to 151 mAh·g⁻¹ at 60 °C at 0.1 C rate and excellent capacity retention of 91% after 100th cycle. NCM811 PTTNW8% Li high-voltage lithium batteries were also demonstrated at a 50 °C, which displayed a superior cycling performance. Therefore, the prepared PEO-TDI-TiO₂ electrolyte is a promising polymer electrolyte for solid- state lithium batteries.