ACS applied materials & interfaces | 2019
Confining Hyperbranched Star Poly(ethylene oxide)-Based Polymer into 3D Interpenetrating Network for High Performance All-Solid-State Polymer Electrolyte.
Abstract
The original poly(ethylene oxide) (PEO) based polymer electrolytes normally show low ionic conductivity and inferior mechanical property, which greatly restrict their practical application in all-solid-state lithium ion batteries (LIBs). In this work, hyperbranched star polymer (HSP) with poly(ethylene glycol) methyl ether methacrylate flexible chain segments is embedded into a three-dimensional (3D) interpenetrating cross-linking network created by the rapid one-step UV-derived photopolymerization of the cross-linker (ethoxylated trimethylolpropane triacrylate, ETA) in the presence of lithium salt. The rigid 3D network framework provides the polymer electrolyte with not only enhanced mechanical behavior, including film-forming and dendrite-inhibiting capability, but also nanoconfinement effects which can speed up polymer chain segmental dynamics and reduce the crystallinity of polymer. Depend on this unique rigid-flexible coupling network, the prepared solid polymer electrolyte shows enhanced ionic conductivity (6.8 × 10-5 S cm-1 at 50 oC), widened electrochemical stability window (5.1 V vs. Li/Li+) and enough mechanical stability to suppress the growth of uneven Li dendrite (the Li symmetrical cells can operate steadily at current density both 0.05 and 0.1 mA cm-2 for 1000 h). Moreover, the assembled LiFePO4//Li cell also exhibited good cycle performance at 50 oC, making the hyperbranched star polymer electrolyte with nanoconfined cross-linking structure have potential application in high safety and high-performance LIBs.