Electrochemical performance of acetalized polyvinyl alcohol membrane for quasi-solid-state supercapacitors

Application of water-based supercapacitor is largely limited by the disadvantages regarding electrolyte leakage and electrolyte corrosion. To address these issues, herein, a quasi-solid-state supercapacitor based on carbon felt (CF) electrode with PVA-KI/H2SO4 mixed gel electrolyte has been fabricated and an stable uniform acetalized polyvinyl alcohol (UAPVA) membrane in acidic condition has been reported for the first time. Given the excellent chemical and mechanical properties, the UAPVA membrane can facilitate I− transportation and still be restored to its original shape after stretching, bending and twisting, which is highly desirable for advanced flexible quasi-solid-state device applications. The as-prepared device exhibits outstanding electrochemical performance with bending 180o and then recovering to 0o. The specific capacitance remains 90.2% after 2400 cycles at 0.75 mA cm−2, indicating its good mechanical flexibility and stability. Remarkably, four quasi-solid-state supercapacitors can easily light up a red LED. The acquired electrochemical results highlight the promise of a successful membrane preparation strategy for the development of quasi-solid-state supercapacitors. Meanwhile, the addition of redox agents to traditional electrolyte solutions can be an effective way to achieve high-performance energy storage devices.