Polycarbonate-based solid polymer electrolytes for Li-ion batteries

This paper reports the synthesis and application of high-molecular-weight poly(trimethylene carbonate) (PTMC) as a new host material for solid polymer electrolyte-based Li-ion batteries. PTMC was synthesized through bulk ring-opening polymerization of the cyclic monomer to yield a high-molecular-weight polymer to serve as a base material for the electrolytes. The thermal properties and ionic conductivity of polymer electrolytes with different salt ratios were measured by TGA/DSC and electrochemical impedance spectroscopy, respectively. The most conductive systems were found at [Li+]:[carbonate] ratios of 1:13 and 1:8, which showed electrochemical stability up to 5.0 V vs. Li/Li+ and an ionic conductivity on the order of 10− 7 Scm− 1 at 60 °C. LiFePO4 half-cells using the electrolytes demonstrated a plateau in the specific discharge capacity around 153 mAhg− 1 after long-term cycling. The functionality of the electrolytes for three-dimensional microbatteries was also confirmed.