Solid Polymer Electrolytes Derived from Crosslinked Polystyrene Nanoparticles Covalently Functionalized with a Low Lattice Energy Lithium Salt Moiety

• Main Authors: Xinyi Mei, Wendy Zhao, Qiang Ma, Zheng Yue, Hamza Dunya, Qianran He, Amartya Chakrabarti, Christopher McGarry, Braja K. Mandal
• Format: Article
• Language: English
• Published: MDPI AG 2020-07-01
• Series: ChemEngineering
• Subjects: crosslinked polystyrene; polymer-bound lithium salts; lithium-ion batteries; solid polymer electrolytes; low lattice energy lithium salts
• Online Access: https://www.mdpi.com/2305-7084/4/3/44

Three new crosslinked polystyrene nanoparticles covalently attached with low lattice energy lithium salt moieties were synthesized: poly(styrene lithium trifluoromethane sulphonyl imide) (PSTFSILi), poly(styrene lithium benzene sulphonyl imide) (PSPhSILi), and poly(styrene lithium sulfonyl-1,3-dithiane-1,1,3,3-tetraoxide) (PSDTTOLi). A series of solid polymer electrolytes (SPEs) were formulated by mixing these lithium salts with high molecular weight poly(ethylene oxide), poly(ethylene glycol dimethyl ether), and lithium bis(fluorosulfonyl)imide. The crosslinked nano-sized polymer salts improved film strength and decreased the glass transition temperature (T_g) of the polymer electrolyte membranes. An enhancement in both ionic conductivity and thermal stability was observed. For example, the SPE film containing PSTFSILi displayed ionic conductivity of 7.52 × 10⁻⁵ S cm⁻¹ at room temperature and 3.0 × 10⁻³ S cm⁻¹ at 70 °C, while the SPE film containing PSDTTOLi showed an even better performance of 1.54 × 10⁻⁴ S cm⁻¹ at room temperature and 3.23 × 10⁻³ S cm⁻¹ at 70 °C.