All solid-state electric double-layer capacitors based on alkaline polyvinyl alcohol polymer electrolytes

Solid-state electrochemical double-layer capacitors (ELDCs) based on alkaline polyvinyl alcohol (PVA) solid polymer electrolytes (SPEs) are prepared. Electrochemical capacitance performance of these capacitors is studied by cyclic voltammetry, galvanostatic charge-discharge testing, and ac impedance spectroscopy. For comparison, two types of EDLC cells are constructed and tested. It is found that an EDLC with a PVA polymer electrolyte exhibits much higher capacitance and longer cycle-life than one with the PP/PE separator. The specific capacitance for the EDLC with the PVA-based SPE is in the range of 100-112 F g−1, and depends on the scan rate or the charge-discharge current rates. The results also indicate that the solid-state EDLC shows a relatively stable specific capacitance of 100 F g−1 after 1000 cycles. The findings suggest that the PVA-based SPE is a promising material for use in EDLCs.