The Effect of Zwitterion on Electrochemical Properties of Quasi-Solid-State Polymer Electrolyte for Supercapacitors
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초록
내용
A quasi-solid-state polymer electrolyte (QPE) is designed by integrating a cross-linked poly(ethylene glycol) (PEG) network with an electrolyte mixture of ionic liquids and zwitterions for supercapacitors. The synthesized QPE exhibits a high ionic conductivity σ (2.8 x 10-3 S/cm at 303 K). The zwitterion-containing QPE shows much higher static dielectric constant (εs = 69) than the zwitterion-free QPE (εs = 48). The enhanced εs also leads to an increase in ion concentration participating in σ. This is because more ions can be dissociated by lowering Coulomb energy (Ec ~ 1/εs) in the high-dielectric medium. The zwitterion-containing QPE-based supercapacitor also exhibits excellent electrochemical performance; i.e., the incorporation of zwitterion results in an increase in specific capacitance (Cs) from 98 to 195 F/g at a current density of 200 mA/g. The proposed strategy provides new insights into the development of QPE designs for practical applications to high-performance solid-state supercapacitors.