Electrochromo-supercapacitor based on direct growth of NiO nanoparticles

In this paper, uniform NiO nanoparticles on different substrates were successfully synthesized by a simple and low-cost solvothermal method. The high capacitance (1386Fg^-1 at 1Ag^-1) and excellent rate capability were achieved for NiO nanoparticle film as supercapacitor electrode. A large optical modulation (63.6% at 550nm), high coloration efficiency (42.8cm²C^-1 at 550nm) and good cycling stability can be achieved when the same NiO nanoparticles are used for electrochromic application. The excellent electrochemical performance is attributed to the uniform nanoparticles morphology and stable chemical bonding of the NiO nanoparticle on the substrates, which shorten the ion diffusion length and greatly facilitated the charge transfer both at the contact interfaces and within the electrode materials during the electrochemical process. In addition, we present a smart supercapacitor which function as a regular energy storage device and simultaneously monitor the level stored energy by visual changes. The findings present great promise for NiO nanoparticle film as practical electrode materials as chromo-supercapacitor.