An initiator-free and solvent-free in-situ self-catalyzed crosslinked polymer electrolyte for all-solid-state lithium-metal batteries

Xin Cai; Zhenwei Cai; Haocheng Yuan; Wenjie Zhang; Shen Wang; Haijun Wang; Jinle Lan; Yunhua Yu; Xiaoping Yang

doi:10.1016/j.jcis.2023.06.059

An initiator-free and solvent-free in-situ self-catalyzed crosslinked polymer electrolyte for all-solid-state lithium-metal batteries

J Colloid Interface Sci. 2023 Oct 15:648:972-982. doi: 10.1016/j.jcis.2023.06.059. Epub 2023 Jun 12.

Authors

Xin Cai¹, Zhenwei Cai¹, Haocheng Yuan¹, Wenjie Zhang¹, Shen Wang¹, Haijun Wang¹, Jinle Lan², Yunhua Yu³, Xiaoping Yang¹

Affiliations

¹ State Key Laboratory of Organic-Inorganic Composites, College of Materials Science and Engineering, Beijing University of Chemical Technology, No. 15 Beisanhuan East Road, Chaoyang District, Beijing 100029, PR China.
² State Key Laboratory of Organic-Inorganic Composites, College of Materials Science and Engineering, Beijing University of Chemical Technology, No. 15 Beisanhuan East Road, Chaoyang District, Beijing 100029, PR China. Electronic address: lanjl@mail.buct.edu.cn.
³ State Key Laboratory of Organic-Inorganic Composites, College of Materials Science and Engineering, Beijing University of Chemical Technology, No. 15 Beisanhuan East Road, Chaoyang District, Beijing 100029, PR China. Electronic address: yuyh@mail.buct.edu.cn.

PMID: 37331078
DOI: 10.1016/j.jcis.2023.06.059

Abstract

Linear polymer (e.g. polyethylene oxide, PEO) based electrolytes have been widely studied due to their flexibility and relatively good contact against electrodes. However, the linear polymers are prone to crystallization at room temperature and melting at moderate temperature, restricting their application in lithium metal batteries. To address these problems, a self-catalyzed crosslinked polymer electrolyte (CPE) was designed and prepared by the reaction of poly (ethylene glycol diglycidyl ether) (PEGDGE) and polyoxypropylenediamine (PPO) with only the bistrifluoromethanesulfonimide lithium salt (LiTFSI) added and with no any initiators. LiTFSI catalyzed the reaction by reducing the activation energy to form a crosslinked network structure, which was identified by calculation, NMR and FTIR. The as-prepared CPE has high resilience and a low glass transition temperature (Tg = -60 °C). Meanwhile, the solvent-free in-situ polymerization technique has been adopted in the assembly of the CPE with electrodes to decrease the interfacial impedance greatly and improve the ionic conductivity to 2.05 × 10^-5 S cm^-1 and 2.55 × 10^-4 S cm^-1 at room temperature and 75 °C, respectively. As a result, the in-situ LiFeO₄/CPE/Li battery exhibits outstanding thermal and electrochemical stability at 75 °C. Our work has proposed an initiator-free and solvent-free in-situ self-catalyzed strategy of preparing high performance crosslinked solid polymer electrolytes.

Keywords: Crosslinked polymer electrolyte; Epoxy; Ionic conductivity; Lithium metal batteries; Self-catalyzed polymerization.