Confining Hyperbranched Star Poly(ethylene oxide)-Based Polymer into a 3D Interpenetrating Network for a High-Performance All-Solid-State Polymer Electrolyte

Abstract

The original poly­(ethylene oxide)-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, a hyperbranched star polymer 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) 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 capabilities, but also nanoconfinement effects, which can speed up polymer chain segmental dynamics and reduce the crystallinity of the polymer. Depending 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 °C), 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 both current densities of 0.05 and 0.1 mA cm–2 for 1000 h). Moreover, the assembled LiFePO4//Li cell also exhibited good cycle performance at 50 °C, making the hyperbranched star polymer electrolyte with a nanoconfined cross-linking structure to have potential application in high-safety and high-performance LIBs.

Carbon dots crosslinked gel polymer electrolytes for dendrite‐free and long‐cycle lithium metal batteries

“…However, PCCEs remain stable until the voltage increases to 4.8 V. The enlarged ESW shows that the combination of PEG and CDs can effectively decrease the activity of the terminal group of CDs 32,33 and also improve the oxidation-resistance ability of PEG. 34,35 Figure 2I-L shows photos of these samples. After incorporation of PEG-CDs, the color of the PVDF film changes to yellow, consistent with the color of the PEG-CDs powder.…”

Bistrifluoroacetamide‐Activated Double‐Layer Composite Solid Electrolyte for Dendrite‐Free Lithium Metal Battery

“…Besides, the C-F polar groups of BTFA weakens the coordination between Li + and the ether-oxygen group, ensuring the uniform and stable deposition on Li metal surface. [48,49] To evaluate the electrochemical behaviors of DSE and BTFA-DSE in real cells, rechargeable SSLIBs systems were assembled with LFP as cathode and Li metal as anode. The initial charge/ discharge profiles of LFP|DSE|Li and LFP|BTFA-DSE|Li cells performing at different rates are shown in Figure 5a,b, respectively.…”

Macromolecular Design of Lithium Conductive Polymer as Electrolyte for Solid‐State Lithium Batteries

“…As shown in Figure 3c, ethoxylated trimethylolpropane triacrylate (ETA) with three C=C bonds and C−O, C=O bonds is applied as cross-linker to form a 3D cross-linking network, improving the mechanical properties of the polymer as reported in the reference. [81] A hyperbranched star polymer with flexible ether groups is embedded in the 3D networks acting as an ionic conducting channel. The highest ionic conductivity at 30 °C was 2.9 × 10 −5 S cm −1 when the crosslinker content reached 20 wt%.…”