Preparation and electrochemical properties of NiSe/Co3O4 nanocomposites
摘要
Supercapacitors are an important electrochemical energy storage device with broad application prospects that play a pivotal role in ensuring energy security and advancing sustainable development. Electrode materials are a key factor that determines supercapacitor performance, making the development of high-performance supercapacitor electrode materials a major focus of current research. This study synthesized NiSe/Co3O4 composite electrode materials via hydrothermal and electrodeposition methods. The effects of different deposition cycles (5, 7, 9, and 11 cycles) on NiSe/Co3O4 electrodes were systematically investigated. Characterization via SEM, XRD, and XPS revealed uniform loading of NiSe nanosheets onto the Co3O4 substrate. Among the prepared samples, the optimized NiSe-9/Co3O4 composite exhibited the best capacitive performance, achieving a specific capacitance of 1650 F g−1 at a current density of 9.0 mA cm−2. Cycling tests demonstrated a capacity retention of 69% after 4000 cycles, while maintaining a Coulombic efficiency of 100%. An energy density of 50.3 Wh kg−1 (432.6 μWh cm−2) and a power density of 744.2 W kg−1 (6400.0 μW cm−2) were delivered by a symmetric aqueous supercapacitor based on the NiSe-9/Co3O4 composite at a current density of 4.0 mA cm−2. After 5000 cycles, the capacitance retention rate was 81.9%. A solid-state supercapacitor was also fabricated which exhibited energy and power densities of 29.85 Wh kg−1 (256.7 μWh cm−2) and 569.8 W kg−1 (4900.0 μW cm−2), respectively, with a capacity retention rate of 66.7% after 5000 cycles. Water-based devices and solid-state devices can continuously illuminate LEDs for 26 min and 6 min, respectively. This result demonstrates that the NiSe/Co3O4 composite exhibits promising practical application potential in energy storage devices.