Preparation Of Transition Metal Sulfides And Zinc Ion Batteries By Electrospinning Technology

With the development of society,the demand for portable electronic devices and electric vehicles has soared,which has greatly stimulated the research enthusiasm of efficient and low-cost energy storage systems.As a new type of aqueous rechargeable battery,nickel-zinc battery has shown great potential due to its advantages of high output voltage,high energy density,low resource cost,safety and environmental protection.However,unfortunately,nickel-zinc batteries also face the problems of low conductivity and fast capacity degradation of nickel-based cathode materials,as well as serious dendrite of zinc cathode.At the same time,traditional Ni-based cathode electrodes are generally consist of none capacity contribution additives and heavy current collectors,resulting in a low percentage of the active materials.Aiming at the above problems of aqueous nickel-zinc battery.This paper takes high conductivity and stable structure cobalt nickel sulfide（NiCo₂S₄）as the research object,and uses electrospinning technology to assist hydrolysis adsorption,carbonization and hydrothermal vulcanization to synthesize NiCo₂S₄functionalized electrospinning carbon fibers（expressed as CNF@NiCo₂S₄）.and then the electrochemical performance of CNF@NiCo₂S₄as electrode materials in the three electrodes was investigated and assembled into aqueous nickel-zinc batteries and quasi-solid-state electrolyte nickel-zinc batteries to evaluate the electrochemical performance.The specific research work is divided into the following three aspects:（1）The polyacrylonitrile/polystyrene（PAN/PS）nanofiber membrane was first prepared by electrospinning technology,and then the NiCo₂S₄nanoparticles were uniformly anchored on the surface of the electrospinning carbon fiber（CNF）by hydrolysis,adsorption,carbonization and hydrothermal vulcanization.Composition CNF@NiCo₂S₄electrode materials.The morphology and structure of CNF@NiCo₂S₄electrode materials were analyzed by FESEM,TEM,XRD and XPS,and electrochemical analysis of CNF@NiCo₂S₄electrode materials by three-electrode test in 3 M Potassium hydroxide（KOH）solution with 0.1 M zinc acetate（Zn（CH₃COO）₂）.As a result,the prepared CNF@NiCo₂S₄electrode materials exhibit excellent electrochemical performance.The area specific capacity of CNF@NiCo₂S₄electrode material can reach 0.34 mAh cm^-2when the current density is 2 mA cm^-2,even at 20mA cm^-2,it still has an area specific capacity of 0.28 mAh cm^-2.Moreover,according to the overall weight,the CNF@NiCo₂S₄electrode can exhibit a high capacity of 218mAh g^-1at 2 mA cm^-2(corresponding to 1.26 A g^-1).（2）Using self-supporting CNF@NiCo₂S₄film as cathode and commercial zinc plate as anode,a aqueous CNF@NiCo₂S₄//Zn battery was prepared.The area capacity of 0.32 mAh cm^-2and the high volume capacity of 35.9 mAh cm^-3at the current density of 2 mA cm^-2,there is still 0.21 mAh cm^-2area capacity at 20 mA cm^-2current density.And at 10 mA cm^-2current density,the capacity still has 83%retention after 2000 charge/discharge cycles.（3）Three different hydrogel electrolytes（polyvinyl alcohol（PVA）hydrogel electrolytes,polyethylene oxide（PEO）hydrogel electrolytes and sodium polyacrylate（PANa）hydrogel electrolytes）were prepared in the course of further study.Ultimately,PANa quasi-solid-state cells exhibit the best electrochemical performance,showing an area capacity of 0.28 mAh cm^-2at a current density of 1 mA cm^-2,and the capacity of82.3%after 500 charge/discharge cycles at a current density of 3 mA cm^-2.