A triPEG-boron based electrolyte membrane for wide temperature lithium ion batteries

Abstract

A triPEG-boron based solid polymer electrolyte (SPE) membrane is fabricated for all-solid-state lithium ion batteries. With an ether oxygen (EO) : LiN(SO₂CF₃)₂ (LiTFSI) molar ratio of 25 : 1, this electrolyte membrane has ionic conductivities of 2.95 × 10⁻⁵ S cm⁻¹ and 1.28 × 10⁻³ S cm⁻¹, and electrochemical decomposition potentials of 5.23 V and 4.88 V, respectively at 25 °C and 120 °C. The all-solid-state LiFePO₄/SPE/Li batteries show high cycling performance in the temperature range of 25–140 °C. At 25 °C and 0.3C, a discharge capacity of 84 mA h g⁻¹ is obtained at the 200th charge–discharge cycle with approximately 100% coulombic efficiency. The batteries also work well at 140 °C and 3C, delivering a discharge capacity of 146 mA h g⁻¹ initially and 113 mA h g⁻¹ after 200 cycles. These results show that this kind of all-solid-state lithium ion battery has a wider working temperature range than conventional liquid electrolyte lithium ion batteries, indicating their suitability for use in fields with high safety requirements.