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Chemically Cross‐Linked Poly(2‐hydroxyethyl methacrylate)‐Supported Deep Eutectic Solvent Gel Electrolytes for Eco‐Friendly Supercapacitors
Author(s) -
Qin Huan,
Panzer Matthew J.
Publication year - 2017
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.201700586
Subject(s) - materials science , chemical engineering , electrolyte , polymer , ionic conductivity , supercapacitor , ethylene glycol , methacrylate , polymer chemistry , deep eutectic solvent , ionic liquid , ethylene glycol dimethacrylate , copolymer , electrochemistry , organic chemistry , eutectic system , electrode , chemistry , composite material , catalysis , alloy , engineering , methacrylic acid
Nonvolatile, ion‐dense electrolytes, such as ionic liquids and deep eutectic solvents (DESs) are attractive candidates for safe, high‐performance electrochemical/electrostatic energy storage devices. In this report, an inexpensive and eco‐friendly DES (1 : 2 mixture of choline chloride/ethylene glycol) has been incorporated into a solid‐state gel electrolyte using a chemically cross‐linked polymer scaffold formed through in situ UV copolymerization of 2‐hydroxyethyl methacrylate (HEMA) and poly(ethylene glycol) diacrylate. A high room‐temperature ionic conductivity of 5.7 mS cm −1 has been obtained for a DES gel containing 13.2 vol % polymer scaffold. Tunable DES gel compressive elastic modulus values, between 14 kPa and 1.0 MPa, could be obtained by varying the polymer content. Clear evidence of hydrogen‐bonding interactions between the poly(HEMA) scaffold and the DES anion was revealed through species self‐diffusivity measurements as well as by FTIR spectroscopy. Using a 22.9 vol % polymer‐supported DES gel as electrolyte/separator in a supercapacitor prototype with activated carbon fabric electrodes, a specific capacitance of 33.3 F g −1 and an energy density of 15.8 Wh kg −1 (based on the mass of two electrodes) were obtained during discharge at a current density of 0.01 A g −1 . This work supports the notion that chemically cross‐linked polymer‐supported DES gel electrolytes are suitable for solid‐state, flexible supercapacitor applications.