Supramolecular polymer cross-linking gel electrolyte for highly stable quasi-solid-state lithium metal batteries
Jiaying Zhang, Lijing Yan, Yue Zhao, Xianhe Meng, Tingli Ma
Abstract
Lithium (Li) metal batteries have the advantage of high energy density, but the Li dendrites risk piercing the separator and causing a short circuit in the battery. Replacing the liquid electrolytes with gel electrolytes is considered an effective strategy to solve the issues. Herein, a poly(vinylidene fluoride- co -hexafluoropropylene) (PVDF-HFP)-based gel electrolyte, improved with multifunctional supramolecular polymer (MSP), was prepared to enhance the cycling stability and energy density of quasi-solid-state Li metal batteries. The MSP addictive constructs a cross-linked network structure with PVDF-HFP matrix and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) through hydrogen bonding, improving the mechanical strength of the composite gel electrolyte (PH-10%MSP-GE) to against the growth of Li dendrites. Moreover, the pre-lithiated sulfonic acid groups, conductive polyether groups of MSP, and the attraction of TFSI – anions, promote the Li-ion transportation of the composite gel electrolyte. Finally, the Li||Li symmetric cell cycle stably for over 450 h. The Li||LiFePO 4 full cell demonstrates a high energy density and excellent cycling stability for over 600 cycles, with a capacity retention rate of up to 98.7%. This work provides valuable insights into the preparation of multifunctional composite gel polymer electrolytes and competitive quasi-solid-state Li metal batteries.