Research On Zinc-air Battery For Electric Vehicle

With environmental problems becoming more and more serious, theclean-energy vehicles come into people’s consideration. In recent years,many countries and automobile companies have been researching anddeveloping the electric vehicles that are of reasonable price and excellentperformance. However, until now, there has no one electric vehicle whichcan be accepted and widely used. There are three reasons that can accountfor this: first of all, the performance of low-cost electric vehicles is not asgood as the traditional cars at the same price. Meanwhile, the chargingprocess of the electric vehicle faces many challenges because of theimperfect infrastructure. Additionally, the electric vehicles of excellentperformance are too expensive, for example, the Electric Vehicle made byTesla. Therefore, it is imperative to develop the high-quality and low-costelectric cars. Power battery, the power source of electric cars, itsperformance directly influences the development of electric cars. Zinc-airbattery is considered to be a potential power battery of electric vehicle,due to its advantages of low cost and high capacity.Previous studies on the zinc-air battery focus on its discharge capacity,power density and the preparation of electrode catalyst. However thispaper started from the research of the single battery, optimized theperformance of the battery and finally fabricated a high-quality zinc-air battery.Zinc-air battery is composed of zinc anode, a cathode, and an alkalineelectrolyte. It owns more positive active substance compared with otherbatteries in the same quality, because its cathode active material is fromthe oxygen in the air, so it tends to possess higher capacity. Besides, zinc,an abundant metal in the crust, is very cheap. However, there are stillsome problems limit the widely use of zinc-air battery such as passivationof the zinc electrode, low utilization rate of the electrode, and chargingproblems etc, remaining to be solved. Focusing on the mentionedproblem, a series of experimental research are performed in this paper.In the beginning, the electrical conductivity of potassium hydroxidesolution was tested and the relationship between conductivity andtemperature was studied. The result demonstrates that the conductivityincreases with the increase of potassium hydroxide mass fraction in thesolution. The conductivity of the solution is highest, when the massfraction of potassium hydroxide in the solution is33%, corresponding tothe7.3mol/L molar concentration of the solution. When the temperatureranges from10℃to70℃, electrical conductivity increases with the riseof temperature, and the relationship conforms Arrhenius equation.The preparation methods of zinc electrode and air electrode are studied.And we designed a battery structure that can change electrode spacing.The battery is assembled into battery pack and the open-circuit voltage of the battery is tested. The open-circuit voltage of the battery is still up to1.4V after placing the battery for3600min.Thirdly, this paper studies the influence of PVDF binder’s content onthe air electrode performance. The results have shown that the airelectrode has the best performance in the condition that the content ofbinder is10%of the total mass of the rest solid powder materials.Fourthly，study the performance of zinc powder electrode, zinc powderelectrode with catalyst and zinc sheet electrode. The results have shownthat the largest differences accurs in performance of zinc powderelectrode between small current discharge and large current discharge.The capacity of zinc powder electrode with catalyst has a part ofreduction at large current discharge. There is few difference in thecapacity of zinc sheet electrode between small current discharge and largecurrent discharge. But all electrodes’ discharge voltage greatly reduces atlarge current discharge.Fifthly，this paper studies the influence of zinc thickness on the batteryperformance. The experiment results have shown that the thinner of thezinc sheet is, the higher of utilization rate and the higher of the capacitydensity will be. The minimum thickness of zinc sheet used in ourexperiment is0.1mm. It has the largest discharge capacity and utilizationrate of zinc.Sixthly，this paper studies the influence of electrode spacing on the battery performance. the results have shown that the battery has the bestperformance when the spacing is3mm. The effect of electrode spacing ismore obvious at large current density discharge.Seventhly，this paper studies the impact of the current density on thecell performance at constant current discharge. The results have shownthat the discharge current density has a significant impact on the batteryperformance. Discharge capacity and discharge voltage decreases as thecurrent density increases. This is because the larger the current is, themore severe concentration polarization is.At last, this paper innovatively combines ultrasonic oscillation with thezinc-air battery and designs a kind of zinc-air battery equipped byultrasound oscillation. The experiment results have shown that ultrasoundcan be used to enhance the discharge capacity and improve theperformance of the battery.