Electrochemical properties of cadmium doped tin oxide film and activated carbon composite electrode

Abstract

In our previous study, we demonstrated the enhanced conductivity and structural properties of cadmium-doped tin oxide thin films synthesized using the pulsed laser deposition technique. While this work established the fundamental improvements introduced by Cd doping, the potential of these films as electrode materials for supercapacitors remained unexplored. Building on this foundation, the present study investigates the electrochemical performance of Cd:SnO₂ thin films in composite electrodes. Cadmium-doped tin oxide and pure tin oxide thin films were fabricated on glass substrates using the pulsed laser deposition technique, resulting in polycrystalline films with a tetragonal rutile structure. Cd doping significantly reduced the electrical resistance of the films from 7.9 × 10³ Ω/□ to 300.9 Ω/□. These Cd:SnO₂ films were further utilized to develop electrode materials by combining them with activated carbon and carbon black in an 85:15 ratio. Electrochemical studies in a three-electrode system revealed that the Cd:SnO₂/Carbon composite electrodes exhibited superior performance compared to undoped SnO₂/Carbon electrodes. The specific capacitance of the Cd:SnO₂/Carbon composite increased markedly from 25.58 ± 1.3 Fg⁻¹ to 71.62 ± 3.6 Fg⁻¹. Further analysis using galvanometric charge-discharge and electrochemical impedance spectroscopy confirmed significant enhancements in energy storage properties. The Cd:SnO₂/Carbon composite achieved an energy density of 12.35 ± 0.6 Whkg⁻¹ and a power density of 1003.41 ± 50 Wkg⁻¹, surpassing the performance metrics of many reported SnO₂-based systems. This study highlights the critical role of Cd doping in improving both the conductivity and electrochemical performance of SnO₂-based electrodes, providing insights into their potential for next-generation high-performance supercapacitor applications.