Preparation And Electrochemical Performance Investigation Of NiCo₂O₄ Core-shell Nanomaterials

There is a high power density of supercapacitors being as new energy storage devices,but the low energy density affects the widespread using of supercapacitors.The micromorphology and phase structure of nanomaterials are regulated by optimizing material composition and experimental conditions of hydrothermal synthesis,and the micromorphology,phase structure and electrochemical performance of the materials are characterized by SEM,XRD,TEM and electrochemical workstations,revealing the intrinsic relationship between different micro-morphologies and electrochemical properties of materials.The investigation results indicate:The effects of reaction materials,time,temperature,concentration,and amount of urea on the micromorphology and electrochemical performance of the materials are studied.Orthogonal experiments are performed on the reaction raw materials,time,temperature,and concentration to determine the impact of each condition,and the specific capacitance of NiCo₂O₄ is 4,651m F·cm^-2 at 1m A·cm^-2 using the optimal synthesis process.After assembled into the device,the capacitance retention rate is 84%at 10m A·cm^-2 after 2,500 cycles tests,the power density of the device is 7,506.33m W·cm^-3.The nanowire/nanosheet composite structure NiCo₂O₄ electrode material is synthesized by a two-step hydrothermal method.It is difficult to grow directly on the surface of Ni foam for the single nanosheet structure,but a large number of uniformly distributed nanosheets is synthesized on its surface by using nanowires as a matrix.Base on the synthesis process of the nanowire/nanosheet composite structure NiCo₂O₄ electrode material,the nanowire/nanowire structure NiCo₂O₄ electrode material is prepared by adjusting the synthesis conditions.The micro-morphology of the electrode material with the best electrochemical performance is a sea urchin shape.The surface capacitance of electrode material is 2,444m F·cm^-2 at 1m A·cm^-2,and the capacity retention rate can reach 84%after8,000 cycles.The power density of the device is 75,000m W·cm^-3.The NiCo₂O₄/MnO₂ core-shell structure material is prepared via two-step hydrothermal synthesis method.The effects of different concentrations on the micro-morphology of the core-shell structure and electrochemical performance are investigated.The area specific capacitance of the sample is 1,754m F·cm^-2 at 1m A·cm^-2.After 8,000 cycles,the capacity retention rate is 175%at 10m A·cm^-2,and the power density of the device is747,000m W·cm^-3.