Ternary metal oxide filled PEO-based polymer electrolyte for solid-state lithium metal battery: The role of filler particle size

Composite polymer electrolytes with fillers exhibit appealing properties, such as high ionic conductivity, good flexibility, and low cost. However, poor compatibility and electrochemical instability, especially at high current rates, are the disadvantages of these electrolytes. In this study, we report the influence of particle size of Li2O. SiO2. TiO2. P2O5 (LSTP) on polyethylene oxide (PEO)-matrix towards the fabrication of Li-metal batteries with a LiFePO4 cathode. Compared to micron-sized particles, the high surface area of the nanoparticles in the polymer matrix is beneficial for improved electrochemical stability at 0.1 mA cm−2. Furthermore, the nanosized particulates facilitate faster ionic conductivity (1.09 × 10−3 S cm−1 at 80 °C) and excellent stability at higher voltage >4.5 V. Our results clearly indicate the role of filler morphology in enhancing the ionic conductivity and stability. Finally, the full cell made of metallic Li anode and LiFePO4 cathode displays a capacity of 110 mAh g−1 (after 100 cycles under 1C at 60 °C) with a reasonable cycle life using such a nanocomposite solid polymer electrolyte.