Poly(Ionic Liquid)‐Based Composite Gel Electrolyte for Lithium Batteries

• Published in: ChemElectroChem Vol. 6; no. 13; pp. 3319 - 3326
• Main Authors: Safa, Meer, Adelowo, Ebenezer, Chamaani, Amir, Chawla, Neha, Baboukani, Amin Rabiei, Herndon, Marcus, Wang, Chunlei, El‐Zahab, Bilal
• Format: Journal Article
• Language: English
• Published: Weinheim John Wiley & Sons, Inc 01.07.2019
• Subjects: Batteries; Cathodes; Cationic polymerization; Charge transfer; composite materials; Electrochemical impedance spectroscopy; Electrolytes; Electrolytic cells; Fillers; gel polymer electrolyte; Glass; Ion currents; Ionic liquids; Ions; Lithium; Lithium batteries; Performance enhancement; poly(ionic liquid); Polymers; Reaction products; Scanning electron microscopy
• ISSN: 2196-0216; 2196-0216
• DOI: 10.1002/celc.201900504

Composite gel polymer electrolyte (cGPE) containing a poly(ionic liquid) (PIL) polymer, imidazolium cation‐based ionic liquid as a solvent, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as salt, and glass fillers with various concentrations have been developed and tested in lithium batteries. cGPEs with 1 wt% glass filler shows the highest ionic conductivity and lithium‐ion transference number with 25 % and 18.18 % improvement compared to gel polymer electrolyte (GPE), respectively. Raman results show that the improvement is due to the improved ion‐pair dissociation of LiTFSI, which causes improvement of Li+ mobility. Cyclic charge‐discharge studies using binder‐free LiFePO4/C cathode and lithium anode for 100 cycles at various C‐rates and at a fixed rate of C/2 for 300 cycles show superior performances compared to other cGPEs and GPE. Electrochemical impedance spectroscopy and scanning electron microscopy confirm uniform deposition of reaction products on the cathode surface, which improves the charge‐transfer reactions and hence improves cyclic performances for cGPE‐1 cells with increasing cycles. Glass fillers: Poly(ionic liquid)‐based composite gel polymer electrolyte containing various percentages of glass micro‐fillers are prepared by solvent‐cast method. The composite electrolytes with 1 wt% glass‐filler content show improved cyclic stability and rate capability at room temperature.