Surface positive-charged modification of inorganic fillers to optimize lithium ion conductive pathways in composite polymer electrolytes for lithium-metal batteries

Meihuang Wang; Liying Tian; Yu Cao; Zhe Su; Wanyu Zhang; Shan Yi; Yayun Zhang; Bo Niu; Donghui Long

doi:10.1016/j.jcis.2022.10.137

Surface positive-charged modification of inorganic fillers to optimize lithium ion conductive pathways in composite polymer electrolytes for lithium-metal batteries

J Colloid Interface Sci. 2023 Jan 15;630(Pt B):634-644. doi: 10.1016/j.jcis.2022.10.137. Epub 2022 Oct 31.

Authors

Meihuang Wang¹, Liying Tian¹, Yu Cao¹, Zhe Su¹, Wanyu Zhang¹, Shan Yi¹, Yayun Zhang¹, Bo Niu¹, Donghui Long²

Affiliations

¹ Shanghai Key Laboratory of Multiphase Materials Chemical Engineering, East China University of Science and Technology, School of Chemical Engineering, Shanghai 200237, PR China.
² Shanghai Key Laboratory of Multiphase Materials Chemical Engineering, East China University of Science and Technology, School of Chemical Engineering, Shanghai 200237, PR China. Electronic address: longdh@mail.ecust.edu.cn.

PMID: 36343555
DOI: 10.1016/j.jcis.2022.10.137

Abstract

The incorporation of inorganic fillers into composite polymer electrolytes (CPEs) is a common strategy to improve ionic conductivity. However, the high surface energy of inorganic fillers typically aggravates poor interfacial contact with polymer chains. Herein, we develop a surface positive-charge modification strategy for enhancing the intermolecular interaction of poly(ethylene oxide) (PEO) electrolytes with inorganic fillers and optimizing lithium ion (Li⁺) conductive pathways in CPEs. The SiO₂ nanoparticles are coated with a polydopamine adhesive layer and then functionalized with a branched polyethyleneimine positively charged functional layer. Such surface modification not only effectively induces more amorphous structure into the PEO matrix but also promotes the dissociation of lithium salts and activates more free Li⁺ in the PEO to accelerate Li⁺ transport. The CPEs achieved a superior ionic conductivity of 6.12 × 10^-5 S cm^-1 at 30 °C. In addition, the modified fillers could induce the formation of a lithium fluoride (LiF)-rich solid-state interphase and correspondingly achieve excellent compatibility with Li metal. The Li symmetric battery using the as-prepared CPEs delivered stable Li plating/stripping performances over 3960 h under 0.2 mA cm^-2. The resulting LiFePO₄|Li battery has an excellent capacity retention of 92.8 % after 260 cycles at 0.5C and 60 °C.

Keywords: Composite polymer electrolytes; Interfacial contact; Intermolecular interaction; Lithium metal battery; Surface modification.