Piezoelectric self-charging cells (SCC) have attracted much interest due to their capability to store piezoelectrically generated energy without a rectification circuit element. In this respect, several approaches have been made to improve the self-charging performance by using ferroelectric nanoparticles and polymer films as separators in the SCC structure. However, self-charging performance of the SCC has been hindered by low conversion efficiency of these devices for practical applications.
Herein, we report a high performance SCC with carbon nanotube (CNT) coated electrodes, realized by employing the ferroelectric poly (vinylidenefluoride-co-trifluoroethylene) P(VDF-TrFE) as a separator in the supercapacitor structure. To effectively charge the SCC, the key requirements are to generate sufficient piezoelectric potential using a ferroelectric separator and to design the electrodes that can store charges separated by piezoelectric potential. To this end, we optimized the supercapacitor structure by adjusting electrode design by spray-coating CNT on Au/polyethylene terephthalate (PET) substrate and the thickness of PVDF-TrFE separator layer. Under the applied force of 0.3 MPa, the SCC fabricated using this approach demonstrates fast charging performance by comparison to other previously reported SCCs, charging up to 1V at relatively short period time. In addition, the based SCC can work as a self-powered strain sensor, effectively detecting different strains without an external power source by the piezoionic effect. The approach used here is simple, effective, and suitable to develope high performance self-charging cell and its potential as a self-powered sensor device.
Acknowledgement: This subject is supported by Korea Ministry of Environment(MOE) as Advanced Technology Program for Environmental Industry Program.