Fabrication and performance studies of a cable-type flexible asymmetric supercapacitor.

In the present work a novel cable-type asymmetric supercapacitor was fabricated using plate-like β-Ni(OH)2 as the positive and activated carbon as the negative electrode, with polyvinyl alcohol-KOH (PVA-KOH) as the gel polymer electrolyte. The β-Ni(OH)2 plates were prepared by a reflux method and the activated carbon was derived from Tamarindus indica fruit shell by chemical activation. The working voltage of the fabricated cable-type asymmetric supercapacitor (ASC) was 1.4 V, and it achieved per-unit-length and gravimetric capacitances of 40.7 mF cm(-1) and 37.5 F g(-1) respectively at 2 mA. Besides, the fabricated ASC delivered a maximum per-unit-length (gravimetric) energy density of 10.7 μW h cm(-1) (9.8 W h kg(-1)) at a power density of 169 μW cm(-1) (154 W kg(-1)). In addition, it exhibited a better capacitance retention, of 88% over 1000 cylces and 76% over 2000 cycles.