Highly conductive V4C3T MXene-enhanced polyvinyl alcohol hydrogel electrolytes for flexible all-solid-state
Xiaoqing Bin1, Minhao Sheng1, Wenxiu Que1
1Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education, International Center for Dielectric Research, Shaanxi Engineering Research Center of Advanced Energy Materials and Devices, School of Electronic Science and Engineering, Xi'an Jiaotong University, Xi'an, China.
Abstract:
Hydrogel electrolytes are an integral part of flexible solid-state supercapacitors. To further improve the low ionic conductivity, large interfacial resistance and poor cycling stability for hydrogel electrolytes, the V4C3T MXene-enhanced polyvinyl alcohol hydrogel electrolyte was fabricated to enhance its mechanical and electrochemical performance. The high-conductivity V4C3T MXene (16,465.3 S m-1) bonding transport network was embedded into the PVA-H2SO4 hydrogel electrolyte (PVA- H2SO4-V4C3T MXene). Results indicate that compared to the pure PVA-H2SO4 hydrogel electrolyte (105.3 mS cm-1, 48.4%@2,800 cycles), the optimal PVA-H2SO4-V4C3T MXene hydrogel electrolyte demonstrates high ionic conductivity (133.3 mS cm-1) and commendable long-cycle stability for the flexible solid-state supercapacitors (99.4%@5,500 cycles), as well as favorable mechanical flexibility and self-healing capability. Besides, the electrode of the flexible solid-state supercapacitor with the optimal PVA-H2SO4-V4C3T MXene hydrogel as the solid-state electrolyte has a capacitance of 370 F g-1 with almost no degradation in capacitance even under bending from 0° to 180°. The corresponding energy density for flexible device is 4.6 Wh kg-1, which is twice for that of PVA-H2SO4 hydrogel as the solid-state electrolyte.
