Cerium Doped NiO Nanoparticles: A Novel Electrode Material for High Performance Pseudocapacitor Applications

The present study demonstrates a novel electrodeposition approach by which Ce3+ doped NiO nanoparticles coated on titanium foils can be processed into a high surface area electrode for rechargeable energy storage applications. A detailed study has been performed to elucidate how cerium substitution doping and redox reaction behaviors underlying these electrodes impact the cyclic and capacitive behavior of the electrode. These nanoparticles were synthesized via molten salt technique and exhibited particle size of similar to 65 nm. From the analysis of the relevant electrochemical parameters, an intrinsic correlation between the substitutional doping amount, capacitance and the internal resistance has been deduced and explained on the basis of relative contributions from the faradic properties of the Ce3+ doped NiO nanoparticles in different electrolytes of varied concentrations. These thin film electrodes exhibited specific mass capacitance value as high as 1500 Fg(-1) and 1077 Fg (1) (1 Ag (1)) measured from cyclic voltammetry and charge discharge curves respectively, which was found to be 5 times higher than the pristine NiO nanoparticles with a capacitance retention of >70% at the end of 2000th cycle. Further, a working model button cell employing these rechargeable electrodes is also demonstrated exhibiting an energy and power density of 92 Wh Kg(-1) and 10 kW Kg(-1), respectively. It has been shown that electrodes based on such nanoparticles can allow significant room for improvement in the cyclic stability and performance of a hybrid capacitor/battery system.