Optimization Of ORR Catalyst And Electrolytic Solution For Aluminium Air Battery

The electric vehicle industry grows rapidly in recent years.In 2018,the sales of electric vehicle have exceeded 1 million in China.The short board of pure electric vehicle is short driving mileage and long charging time.It can’t meet the needs of large and wide market such as long-distance bus,double-shift rental,urban logistics,long-distance transportation and so on.Therefore,it is imperative to study on-board batteries with high energy density and power density.Aluminum Air Battery is a kind of fuel cell with high energy density.The theoretical energy density of aluminium anode reaches 8100Wh/kg,and the energy density of aluminium air battery system exceeds 300Wh/kg,which has attracted researchers’ wide extensive attention.At present,great progress has been made in the research of aluminium anodes and catalysts of aluminium air batteries.A variety of oxygen reduction reaction catalysts with catalytic efficiency close to Pt/C have been developed,and the utilization rate of some aluminium alloy anodes has been more than 85%.We can see low power saltwater lamps equipped with aluminium air batteries in the market.However,the industrialization of high-power aluminium air batteries has not yet been realized.The main reasons are catalyst cost,electrolyte,battery system and so on.In order to reduce overpotential and polarization in oxygen reduction reaction(ORR)of fuel cell,ORR catalyst with strong conductivity,stable chemical performance and high catalytic activity is necessary in order to reduce electrochemical polarization in oxygen reduction process.One of the reasons that the industrialization of high-power aluminium air batteries has not been realized is that the research on aluminium air electrolyte is relatively few.The technical feasibility analysis and economic analysis of aluminium air batteries are still in the blank stage.The purpose of this paper is to provide valuable reference materials for the industrialization of aluminium air battery.The main work of this thesis is summarized as follows:(1)In this paper,ORR catalysts for LaMn〇3 and various carbon materials are prepared by sol-gel method.The electrochemical test shows that LaMnO 3-CNTs has obvious synergistic catalytic effect,which is mainly manifested in the corrected initial potential,half-wave potential and higher limit current density.Compared with commercial Pt/C catalysts,LaMnO 3-CNTs exhibits better long-term durability in alkaline solution.The agglomeration of LaMnO3 nanomaterials can be avoided by compounding LaMnO3 precursor with CNTs and then synthesizing LaMn〇3 nanomaterial.The maximum power density of the catalyst is 265.8 mW cm-2,which is much higher than LaMn〇3-graphene and LaMnO 3-acetylene black.It is confirmed that LaMnO 3-CNTs has broad application prospects as the catalyst for aluminum air battery.In the methanol tolerance test,the ORR performance of LaMnO 3-CNTs in alkaline methanol solution is still very good,which indicates that LaMnO3-CNTs also has a good application prospects in the field of methanol fuel cells.The preparation of the catalyst is simple and easy to scale up.(2)This thesis compares the electrochemical performance of two typical electrolytes(salt solution and alkaline solution)for aluminium air batteries by a self-made electrolyte testing device for aluminium air battery,and also compares the differences of other technical indicators(such as viscosity,temperature,energy density of aluminium anode,crystal structure and micro-morphology of products),to provides a basis for the selection of electrolyte for aluminium air batteries.The experimental data confirms that the electrochemical impedance of the Al-air battery using alkaline solution as electrolyte is smaller,the power density is higher,the viscosity and temperature of the electrolyte are smaller,and the energy density of the aluminum anode is higher.The energy density and efficiency of the aluminum anode for Al-air battery using salt solution as electrolyte is 1760 Wh/kg and 21.7%,respectively,and while using alkaline solution as electrolyte is 2985.8 Wh/kg and 36.9%,respectively.Referring to the technical specifications of Trumpchi Gb3,under the condition of using alkaline electrolyte,the energy produced by consumption of 1 kg Al can drive a Trumpchi GE3 for 18 km.For high-power aluminium air batteries,alkaline solution is better as electrolyte.In this thesis,the effect of reaction products(Al(OH)3)on Al-air battery under alkaline condition is discussed.As more and more aluminum hydroxide is dissolved in the NaOH solution(from 1g/100 ml to 40g/100ml),the voltage of aluminum air battery only drops 0.1V The experimental data shows that the effect of reaction products on the electrochemical performance of Al-air battery is very small.In this thesis,it is also confirmed that the constant current discharge of Al-air battery with acidic electrolyte can only be maintained for 10 ? 20 minutes,and the energy density of Al anode is very low.The energy density of all aluminum anodes are less than 500Wh/kg.Acidic solution is not suitable as aluminium air battery electrolyte.Furthermore,it has been demonstrated that carbonation of alkaline electrolyte has adverse effects on the electrochemical performance of aluminium air batteries.When more and more CO2 dissolved in the NaOH solution(from 0 to 1.8mol CO2/L),the voltage of aluminum air battery drops 0.15 V When alkaline electrolyte is not used,it should be closed storage.(3)In this thesis,the market research,technical feasibility analysis,economic analysis and project risk analysis of UPS equipped with aluminium air batteries are carried out by means of mathematical modeling and technical economics,which fills the blank in this field.The result shows that the aluminium-air battery has the characteristics of high energy density and low power density,the energy density is 311Wh/kg,which is twice that of lithium battery;the power density is 17.48W/kg,which is only 10% of lithium battery.In online UPS equipped with aluminium-air battery the replacement period of aluminium anode is 5 years in actual working condition;and the replacement cycle of electrolyte is 2.5 years.Replacing some lead-acid batteries of online UPS with aluminium air batteries can not reduce the quality of UPS.It is technically feasible to use online UPS with aluminium air batteries as a backup power source in communication base stations.If UPS is used for more than 5 years,the cost of online UPS equipped with aluminium air batteries is cheaper than that of conventional online UPS.The cost of air electrodes for aluminium air batteries is much higher than that of electrolytes and aluminium anodes.The longer service time of the air electrode of the aluminium air battery is,the better the economy of the battery.Improving the power density of air electrodes and reducing the production cost of air electrodes is an important step in the industrialization of aluminium air batteries.Combining with the actual situation of aluminium air battery,the actual demand of communication base station for standby power supply and the existing technical standards,a preliminary design scheme of on-line UPS suitable for communication base station,2kVA and equipped with aluminium air battery is proposed,which fills the blank in this field.