Study On The Manufacturing Technology For Uniformity Of The Power Lithium-ion Battery

With its high output voltage,high specific energy,high capacity and high energy conversion efficiency,low self-discharge rate,long cycle life,non-memory effect and etc.to their advantage,the power lithium-ion battery has become the mainstream in the current power battery markets.The power type lithium-ion battery can be used as a source of power after cell group.However,the non-uniformity of individual cell has become one main reason for the issues as poor performance,short cycle life and low-security.In view of the current situation of the relatively backward manufacturing technology of lithium ion battery in China,this paper studies the influencing factors of the consistency of lithium ion battery.The specific contents of this paper are as follows:1.The lithium-ion battery manufacturing technology is a major cause of effecting battery uniformity.The main technological processes of three production stages–battery pole piece manufacturing,cell assembling,and cell testing and sorting were analyzed.By studying on the relationship between the battery manufacturing equipment at the present stage and the consistency,the key factors which influence the battery performance and uniformity can be obtained in the manufacturing process.2.In order to get the key factors which affect the consistency of the battery,the grey correlation degree and AHP method are used to analyze the consistency.Firstly,we acquire raw data of weight analysis by expert scoring.The second,the weights of experts and factors are obtained by using grey relational theory and analytic hierarchy process(AHP).Lastly,we united expert weight and factor weight by weighted arithmetic means to obtain the comprehensive weight of the index.According to weight size,we can get several key technology affecting uniformity which are pole piece rolling,vacuum drying,slurry mixing and liquid injection process.3.The specific factors that cause the thickness uniformity of the sheet are analyzed,and then the results show that the uniformity of the thickness uniformity is directly related to the roll deflection.By using ANSYSWorkbench software,the influence of roll diameter,rolling force and sheet width on the roll deformation is simulated and analyzed.We can conclude that the roll diameter,the rolling force and the sheet width have an effect on the uniformity of the battery pole piece.4.Through the study of the vacuum drying process of the core,it is concluded that the uniformity of the temperature distribution in the drying chamber is the key to the drying of the core.Using the Fluent simulation software to simulate the flow field in the drying chamber,the distribution of the flow field in the drying chamber is obtained when the inlet velocity and the pressure change.The simulation results show that the inlet air velocity and the pressure inside the chamber have great influence on the wind speed in the chamber,which affects the uniformity of the core drying.