Enhancing Energy Density in Flexible All-Solid-State Supercapacitors via Dielectricizer Zwitterion-Containing Quasi-Solid-State Polymer Electrolyte

H Kwon and S Kim and H Park and JS Park and J Park and Y Lee and SJ Yang and UH Choi, ADVANCED FUNCTIONAL MATERIALS, 34 (2024).

DOI: 10.1002/adfm.202406727

To improve the energy density of quasi-solid-state polymer electrolyte (QPE)-based supercapacitors, the design of zwitterion-containing QPE (ZQPE) with a high dielectric constant (epsilon s) is proposed. This enhancement would increase the capacitance of ZQPE-based supercapacitors, given the direct proportionality between capacitance and dielectric constant. The optimized ZQPE exhibits a high ionic conductivity (2.2 x 10-3 S cm-1) and good mechanical robustness (4.1 x 104 Pa) at room temperature. The ZQPE shows a much higher static dielectric constant (epsilon s = 69) than the zwitterion-free QPE (epsilon s = 48), as supported by density functional theory calculations and molecular dynamics simulations. The flexible all-solid-state supercapacitor, fabricated with ZQPE and activated carbon electrodes, exhibits excellent electrochemical performance. The incorporation of zwitterion to QPE results in an increase in specific capacitance from 178 to 225 F g-1 with a wide operating potential window (0-4 V). The ZQPE-based supercapacitor also exhibits a large energy density of 142 Wh kg-1 at a power density of 464 W kg-1 and remarkable long-term electrochemical and mechanical cycling stability, retaining 80% of its capacitance retention over 10 000 cycles and even under rolling deformation for 1500 cycles. This strategy offers new insights for developing QPE designs for high energy density all-solid-state supercapacitors. Zwitterion-containing quasi-solid-state polymer electrolytes (ZQPEs) are developed with high dielectric constant zwitterions. The optimized ZQPE demonstrates excellent ionic conductivity, flexible mechanical performance, and high static dielectric constant. Furthermore, the flexible all-solid-state supercapacitor fabricated with ZQPE exhibits high specific capacitance, substantial energy density, and long-term cycling stability even under mechanical deformation. image

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