LaCoO₃ doping in PVDF-based electrolytes with long-cycle performance and excellent interface compatibility of solid-state batteries in a wide temperature range

Composite polymer electrolytes (CPE) have attracted considerable attention due to their potential to achieve high flexibility and large energy density. However, their practical application is hampered by their suitability at a single temperature and severe lithium dendrite growth. In this work, we have doped the perovskite inorganic filler LaCoO₃ into polyamide (PI) nanofibers and constructed a LaCoO₃/PI/PVDF CPE. Electrochemical characterization of the CPE and density functional theory calculations performed for it show that perovskite nanofibers have abundant oxygen vacancies, which are conducive to accelerating the dissociation of lithium salts and releasing more free lithium ions. Li//Li symmetric batteries exhibit excellent long cycle performance (over 3000 h) at 30 °C, and LiFePO₄//Li batteries exhibit excellent cycling performance with over 1000 cycles at (0.5 C, 30 °C) and 400 cycles at (0.2 C, 60 °C), which can be realized with high voltage cathode NMC 811. The physical properties of the CPEs are also quite outstanding, with good thermal stability as it can withstand a high temperature of 200 °C and tensile strength up to 12.01 MPa. This work presents a new idea for designing CPEs with high safety and excellent electrochemical properties, which can provide stable circulation over a wide temperature range.