Cellulose-Br-initiated imidazolium cation and ether linkage regulation of all-solid-state polymer electrolyte for advanced lithium transfer and battery performance

The all-solid-state polymer electrolyte (SPE) with superior electrochemical performance and stability is the most significant part for the development of high safety and reliable batteries . In this work, the ether linkage and imidazolium ionic liquid are incorporated into the modified macromolecular cellulose network via atom transfer radical polymerization for the construction of brush-like cellulose bromide-poly(ethylene glycol) methyl ether methacrylate@1-vinylimidazole ionic liquid (CB-PEGMA@IL) and cellulose bromide-1-vinylimidazole ionic liquid@poly(ethylene glycol) methyl ether methacrylate (CB-IL@PEGMA) composite polymers . The crystallinity of pristine CB is largely decreased on account of the synergistic effect of ionic liquids and ether linkage. In particular, CB-PEGMA@IL presents a lower crystallinity and superior electrochemical performances than that of the CB-IL@PEGMA. With a wide electrochemical stability window (5.3 V vs Li/Li + ), the CB-PEGMA@IL based SPE presents a high ionic conductivity (1.2 × 10 −4  S cm −1 ) and record Li + transference number (0.32). LiFePO 4 /Li battery assembled with CB-PEGMA@IL-SPE shows excellent cycling performance (beyond 150 cycles at 0.2 C) and good rate capacity. Moreover, the overpotential of CB-PEGMA@IL-SPE based symmetric battery can keep ∼0.03 V even after 200 h cycling (100 μA cm −2 ). The soft-packed battery based on CB-PEGMA@IL-SPE can withstand bending and present stable voltage output upon folding at various angles. This rigid-flexible hybrid SPE provides a unique candidate for the fabrication of wearable high-tech electronic devices.