The Synthesis And Electrochemical Performance Of Nickel-based Supercapacitor Electrode Materials

Due to its higher theoretical capacitance,low-costs and simple preparation,Ni?OH?₂and Ni O electrode materials have attracted scholars signicant attention.In this paper,Ni?OH?₂ and Ni O electrode materials with porous structure has been successfully prepared by a hydrothermal method.The relationship between the microstructure and electrochemical properties of the electrode materials were studied.Effect of microstructure and electrochemical performances of Ni?OH?₂ and Ni O electrode materials have been investigated using X-ray diffraction?XRD?,scanning electron microscopy?SEM?,Transmission Electron Microscopy?TEM?,Constant current charge discharge,cyclic voltammetry?CV?and electrochemical impedance spectroscopy?EIS?measurements.Microporous ?-Ni?OH?₂ with three-dimensional flowerlike morphology were synthesized from the reaction product OH-and nickel ions by a modified homogeneous precipitation method,where CO?NH2?₂ could be acted as a chelating agent at lower temperatures,and source material of OH-utilizing the hydrolysis reaction at high temperatures.The pore diameter and the specific surface area of ?-Ni?OH?₂ was 1.7 nm and 163 m2 g-1,respectively.The ?-Ni?OH?₂ material used as an electrode in 6 mol L-1KOH electrolyte exhibited a specific capacitance of 1025 F g-1 at a current density of 5 A g-1,and could still retain 917 F g-1 at 10 A g-1 and 649 F g-1 at 20 A g-1,respectively.The test results show that the capacitance retention of the electrode materials at the current density of 10 A g-1 is 29% after 500 cycles.Mesoporous Ni O materials were obtained by heat treatment of microporous?-Ni?OH?₂.The specific surface area and the pore diameter of Ni O was 140 m2 g-1 and 3.6nm,respectively.The Ni O material used as an electrode in 6 mol L-1 KOH electrolyte exhibited a specific capacitance of 289 F g-1 at a current density of 5 A g-1,and could still retain 262 F g-1 at 10 A g-1 and 257 F g-1 at 20 A g-1,respectively.In addition,almost nodecrease of the capacitance was observed after 4000 th charge-discharge cycles at a current density of 10 A g-1.The core-shell structure Ni?OH?₂/Co?OH?₂ electrode material was synthesized via a simple one-pot procedure by homogeneous precipitation technique.The specific surface area of Ni?OH?₂/Co?OH?₂ electrode materials was 229 m2 g-1.A high conductive Co?OH?₂distributed in the peripheral nanolayer of the composites,which is beneficial to capability and cycle stability.Their specific capacitance is up to 1202 and 1022 F g-1 at the current densities of 10 and 20 A g-1,respectively.Furthermore,the capacitance retention of the electrode materials at the current density of 10 A g-1 is 98% after 5000 cycles.Synthesis method provides a novel simple route to fabricate heterostructure materials for capacitors with high electrochemical performance.