Study On The Microstructure Control Of Nickel-based Electrode Materials And Their Electrochemical Performance

The performance of supercapacitors mainly depends on the electrochemical reaction between electrolyte ions and activated materials.To improve the electrochemical performance,the charge transfer during the electrochemical reaction should be enhanced.On the other hand,the stability of the activated materials depends on their endogenous and exogenous structural stability,which determines the cycle stability of the supercapacitor.In this dissertation,based on the nickel-based electrode materials with high theoretical specific capacitance,various methods such as particle size reduction,ions doping and microstructure control were carried out to solve the issues of charge transfer and material stability,trying to obtain high-performance supercapacitors.The main results are as follows:（1）The NiO nanoparticles with small size were synthesized by an one-step solvothermal method with CTAB as an additive.The obtained nanoparticles exhibited high electrochemical performance.Their specific capacitance were as high as 515.6 C g^-1 at 3.1A g^-1 and their capacitance retention rate kept 90%after 5000 cycles of charge and discharge.（2）The Zn²⁺doped Ni（OH）₂ porous spheres were prepared by using a high-shear mixer.The structural stability of Ni（OH）₂ and the transport of electrolyte ions were enhanced due to the doped Zn²⁺and the hierarchical nanostructures of Ni（OH）₂.The obtained Ni（OH）₂ porous spheres have excellent electrochemical performance.Their specific capacitance were as high as 1274 C g^-1 at a current density of 2.1 A g^-1,and its cycle stability had also been greatly improved.Their capacitance retention after 2000 cycles of charging and discharging was increased to 69%.（3）The 2D nanoflakes-interlaced nickel sulfide was obtained by a chemical bath method through adjusting the reaction temperature and pH.This nanoflakes-interlaced structure improved the structural stability of materials and promoted the transportation of electrolyte ions.Therefore,the obtained nickel sulfide showed improved electrochemical performance.Its specific capacitance reached 963.6 C g^-11 at the current density of 2 A g^-1,and it still kept a high capacitance retention of 81%after 8000 cycles of charge and discharge.