NiWO4 nanoparticle decorated lignin as electrodes for asymmetric flexible supercapacitors

Abstract

In order to meet our increasing energy demand, a flexible, lightweight, and highly organized energy management strategy is needed for flexible supercapacitors. With that perspective, an anode electrode has been designed by depositing NiWO₄ nanoparticles on lignin (lig) on an aluminum substrate. A supercapacitor was assembled by using Al/lig–NiWO₄ as the anode, Al/AC (activated carbon) as the cathode, and PVA/H₃PO₄ gel as the electrolyte. Superior electrochemical performance was achieved even after 2000 cycles of charge and discharge study. The maximum specific capacitance at 0.13 A g⁻¹ is 17.01 mF cm⁻², which is more than 42 times that reported. The capacitance retention is maintained at about 97% after 1000 cycles, and at 84% after 2000 cycles. The maximum energy and power densities are 2 W h cm⁻² and 100 W cm⁻², respectively. A series of the composition of lig : NiWO₄ : PVDF was tested to optimize the electrochemical performance. It was found that the best performance was achieved for the ratio (10 : 80 : 10) that had predominantly NiWO₄ nanoparticles. The remarkable electrochemical performance of this new class of capacitors makes them useful for a wide variety of electronics.