Enhanced electrochemical properties of NiCoLDH/Co3S4 heterojunction for high-performance supercapacitors applications

Supercapacitors have garnered significant attention in energy storage due to their characteristics of high-power density and energy density. Among various electrode candidates for supercapacitors, heterojunctions have shown great potential. In this study, NiCoLDH/Co₃S₄ heterojunctions were fabricated via a binder-free strategy involving the growth of Co-ZIF-L on nickel foam, followed by sulfurization and urea-assisted hydrothermal growth of NiCoLDH. The resulting heterojunctions exhibited significantly enhanced specific capacitance compared to pristine Co₃S₄ and NiCoLDH. The optimized NiCoLDH/Co₃S₄ −90 min sample achieved a maximum specific capacitance of 624.2 mAh·g⁻¹, attributed to the synergistic effects between Co₃S₄ and NiCoLDH. Density Functional Theory (DFT) calculations revealed that the enhanced performance stemmed from the high electrical conductivity of the heterojunction and the interfacial electric field created by charge redistribution at heterojunction interface, which can accelerate the transport of charged particles, and enhance the specific capacitance. When assembled into an asymmetric supercapacitor with activated carbon (AC) as the anode, the device achieved an energy density of 83.8 Wh·kg⁻¹ and a power density of 850.0 W·kg⁻¹ at 1 A·g⁻¹, with 94.2 % capacity retention after 5000 cycles. These results demonstrate the potential of the NiCoLDH/Co₃S₄ heterojunction for high-performance energy storage applications and provide a promising strategy to enhance the electrochemical performance of transition metal sulfides (TMSs) and layered double hydroxides (LDHs) as electrode materials.