Surface-Modified ZnCo₂O₄ Nanoparticles as Binder-Free Electrode for All Solid-State Asymmetric Supercapacitor

Choice of electrode material is crucial to the development of high-performance supercapacitors. Since surface properties are key to the performance of an electrode material for supercapacitors, surface chemical treatment of electrode materials is an interesting topic of research. ZnCo2O4 (ZCO) is a low-cost binary transition metal oxide with high theoretical conductivity and charge storage capacity making it a good choice for supercapacitor electrode. Herein, we present a systematic investigation of the influence of four different surface modifier (3 surfactants, 1 mineralizer) on ZCO electrode directly grown on Ni foam to compare the relative influence on the performance of the modified ZCO electrode. Analyses of the modified ZCO electrodes revealed the formation of cubic spinel phase of ZCO with average particle size of similar to 30 nm. The sodium dodecyl sulfate (ZCO-S) modified electrode (ZCO-S) exhibited the best electrochemical performance with specific capacitance of 1988 F/g at 1 A/g and 87 % capacity retention after 7000 cycles at 10 A/g. Further, an all-solid-state asymmetric supercapacitor (ASC) was fabricated with ZCO-S on Ni foam and carbon nanotube combination which exhibited specific capacitance of 102 F/g at 1 A/g corresponding to power density of similar to 1599 W-kg(-1) establishing ZCO-S as a very good electrode material for supercapacitor.