The Study On The Nickel Sulfide As Positive Electrode Of Lithium-ion Battery

It is of great significance to develop renewable and clean energy storage equipment,because people pay more attention to today's environmental degradation and energy crisis result of over-exploitation of traditional fossil fuels.Lithium-ion batteries which are essential in our daily life,are widely used as an innovative invent replace traditional energy in portable electronic market because of its advanced merit.The capacity of lithium-ion battery cathode materials have been commercialized is generally low,and various materials have their own limitations,so their performance still lies behind the demands of high-power and long life applications.Exploiting new types of electrode materials with high specific capacities,especially the cathode materials,has played one of the most important roles in the development of lithium ion batteries.During various type of cathode materials for lithium-ion batteries,the transition metal nickel sulfide are seen as a value electrode materials with higher theoretical capacity and lower cost.However,the poor cycle stability in the charging-discharging process and lower electrical conductivity?as compared with the carbon material or alloy material?of transition metal nickel sulfides have hold back their applications in the cathode materials for lithium-ion batteries.Two common ways are widely used to overcome these shortages,including developing a variety of nanostructure materials,complexing with carbons and direct in situ growing electrode materials on conductive substrates.This thesis mainly content is including:the evolution,structures,working principles and research progress of lithium-ion batteries.Then some typical commercial cathode materials and their synthesis method are introduced.The instrument and reagent used in this work and characterization of the materials are introduced thoroughly.In this work,simple two hydrothermal methods are developed to make unique nickel sulfide nanomaterials.Firstly,flower-like microspheres structure precursor formed by interconnected Ni?OH?₂ nanosheets was synthesized,then through sulfured reaction formed NiS microspheres and the nanostructures is based on the precursor's;and the physically morphology and electrochemical performance test are carry out;then Ni₃S₂ was in situ developed on the Ni current collector.The influence of hydrothermal temperature,time,and precursor density on electrochemical performance were research.The results of this study are following:in this work we successfully grew Ni₃S₂ on Ni foam as a cathode material;electrochemical performance test was achieved by button cells which were directly assembled in an glove box fulling with argon;at a current density of 1 A/g,the initial capacity of battery is about 1450mAh/g and then remain1000mAh/g;the material have higher charge-discharge efficiency but poor stability;though complexing with carbon,the cycle life also low.After comparing and analyzing the conditions,the factors are selected as follows:hydrothermal temperature for160?,reaction time for 6 h,the weight of precursor 20 mg.