Fabrication of nickel oxide carbon nanocomposites for supercapacitor applications

Abstract

The global shift of energy production from fossil fuels to renewable energy sources requires more efficient and reliable electrochemical energy storage devices. In particular, the development of electric or hydrogen powered vehicles calls for muchhigher- performance batteries, supercapacitors and fuel cells than are currently available. As far as supercapacitors are concerned, due to their low cost, easy availability, large active area and good electric conductivity, carbon based materials currently dominate the market as core electrode materials. However, the exploitation of pseudocapactive/faradaic effects to enhance doublelayer capacitance seems to be an alternative means to develop the next generation of high-power and high-energy electrochemical capacitors. However, pseudocapacitors frequently suffer a number of adverse shortcomings including charge storage instability, an increased resistance and short life cycle. In this thesis, above challenges have been explored through the investigation of NiO nanostructures as a promising electrode material in combination with nano-carbon sourced from a relatively cheaper source-camphor. The formulation of new electrolyte systems like ionic liquid was also been tried to improve the operating voltage window of the system which in turn could improve the energy density as well as power density values. In the first part of this thesis, NiO nanoparticles were synthesized as a control system through a molten salt technique. A detailed study has been performed to elucidate the effect of intra- and inter-particle by inclusion of ceria (1 5 wt %) as well as addition of carbon in these nanoparticles and its impact on the electrochemical performance. From the analysis of the relevant parameters, an intrinsic correlation between the effect of ceria, conductance and the internal resistance has been deduced and explained on the basis of cerium as a dopant and ceria as an additive which could reduce the rate of oxygen evolution. ..