PVP-assisted enhancement in ion storage performance of sol-gel derived nano-structured NiCo2O4 thin films as battery-type electrode

NiCo2O4 thin films were successfully deposited on glass and ITO substrates by sol-gel method. In order to improve the electrochemical ion storage performance, different amounts of polyvinylpyrrolidone (PVP) were added to the solutions as porogen agent, which was totally degraded during the post-annealing process at 500 degrees C, as confirmed by Fourier transform infrared (FTIR) spectroscopy. The electrode with about 0.07 g/cm(3) PVP content in the solution, exhibited 65% higher specific capacity comparing with the electrode fabricated without PVP, due to significant nano-sized porosity remained after degradation of polymer chains, as displayed by field emission scanning electron micrographs (FESEM) of the surface and cross section of the samples. Also the electrochemical measurements in 1 M KOH aqueous electrolyte revealed the ion storage mechanism of the-fabricated samples is battery-type.