Study On Electrode Preparation And Performance Of Ni-Zn Aqueous Battery

The continuous development of human society has intensified the consumption of energy.According to the current consumption rate,mankind will soon face an energy crisis,and our country is no exception.At present,a large portion of China’s fossil energy sources,such as oil and natural gas,are dependent on foreign imports.Energy has long been an important issue in China’s development.With the rapid development of portable electronic equipment and various kinds of automobiles,higher requirements are placed on energy storage devices,and thus energy storage technology is regarded as an important national strategy.In the past decades,flexible alkaline metal ion batteries(Li,Na,K)have been developed.Which have the advantages,high energy density,but also a series of problems,such as high production cost,and electrolyte is toxic organic electrolytes,which limits its development.One of the most important components of electrochemical energy storage equipment is the secondary water battery.The most important feature of this kind of battery is the use of aqueous electrolyte.Comparing with organic electrolyte,it has the advantages of higher conductivity,higher safety,lower production cost,and etc.Its disadvantage is its low energy density and low energy density.The best way to solve this problem is to increase the specific capacity of electrode materials.Nickel hydroxide is a promising electrode.In order to improve the performance of the cathode materials,a layer of one-dimensional nitrogen-doped carbon nanofibers was deposited on the carbon cloth,and then a mixture of nickel(Ⅱ)hydroxide and nickel hydroxide was synthesized on the carbon cloth by hydrothermal method.In order to match with the cathode material,the zinc anode material with high theoretical capacity was chosen in this paper and we design and fabricate carbon-doped ZnO nanorods to suppress these problems.The specific work is as follows:1.First of all,polypyrrole nanofibers(PPy)were deposited on carbon cloth by electrodeposition,and then carbonized into nitrogen-doped carbon nanofibers by annealing in Argon,then a two dimensional mixture of nickel hydroxide and nickel(Ⅱ)hydroxide was synthesized via hydrothermal synthesis on one dimensional nitrogen doped carbon nanofibers.The binderless three dimensional structure facilitates the transport and diffusion of electrons and ions for faster chemical kinetics processes.Then the electrochemical workstation was used to test the performance of the sample material,the results show that the specific capacity of the electrode material is 0.32mAh cm-2 at current density of 1 mA cm-2.When the current density is increased by 10 times,the specific capacity remains 84.3%.After 2000 cycles at the current density of 10mA cm-2,the area specific capacity remains 92.86%of the initial capacity.2.Zinc oxide is a common negative electrode material,which is easily dissolved in alkaline electrolyte and the growth of zinc dendrites limits its electrochemical energy storage properties.The carbon-doped ZnO nanorods were synthesized by one-step hydrothermal method and then annealed in Argon at high temperature to form carbon-doped ZnO nanorods.After high temperature annealing,many holes appeared on the nanorods,which not only provided more active sites for the materials,but also facilitated better contact between the materials and the electrolyte.Moreover,carbon doping can not only inhibit the formation of zinc dendrites,but also improve the stability of the material.The sample material is subjected to electrochemical testing using an electrochemical workstation and the test results show that the specific volume of the material remains 87.9%after 2000 cycles at the scanning rate of 10 mV s-1,which shows that the material has good cycle stability.Finally,an aqueous alkaline Ni-Zn battery has been fabricated with nitrogen doped carbon nanofiber/hydroxyl nickel(Ⅱ)hydroxide as the positive electrode and carbon doped zinc oxide as the negative electrode.The battery was then tested using an electrochemical workstation.The results show that the maximum energy density is 0.437 mWh cm-2 and the maximum power density is 32.4 mW cm-2,and the area specific capacity remained 72.1%of the original capacity after 2000 cycles at the current density of 10 mA cm-2,The results show that the material has high energy density,high power density and good cycle stability.