Reduced Self-Discharge of Supercapacitors Using Piezoelectric Separators

The application of supercapacitors for long-term energy storage is largely limited by their self-discharge behavior. Finding an effective approach to suppress self-discharge remains a great research challenge. Herein, a porous poly(vinylidene fluoride) (PVDF) membrane with a piezoelectric effect is employed as supercapacitor separators for reduced self-discharge. The PVDF membrane is prepared via a phase-inversion method followed by polarization to induce piezoelectricity. Self-discharge tests indicate that both open-circuit voltage (OCV) decay rate and leakage current of the supercapacitors with piezoelectric PVDF separators are reduced by more than 30% compared to those with nonpiezoelectric separators. The much lower self-discharge rate can be attributed to the impeded diffusion of electrolyte ions across the polarized PVDF separators.