Study On Pressure Effect On Performance And Life Cycle Of Soft-Packaged Lithium-ion Battery

Environmental pollution and energy shortage have always been two major problems faced by automobile enterprises.Electric vehicles have the characteristics of energy saving,environmental protection and low noise.They have gradually become the hot pursuit of domestic and foreign automobile manufacturers.Electric vehicles can also solve these two problems very well.In recent years,with the popularity of electric vehicles,power batteries have become more and more important and difficult to promote new energy vehicles.In this paper,three-component soft-packed lithium-ion batteries are taken as the object,and the relationship between pressure,battery expansion and battery life is studied and analyzed by experimental means.The main work of this paper is as follows:(1)Review and analyze the current status and future development trends of electric vehicles and power batteries at home and abroad,introduce the internal structure and working mechanism of lithium battery cells,learn the basic terminology of lithium ion batteries,and focus on the attenuation mechanism of lithium ion batteries.(2)Analyzing the structure and working principle of lithium-ion battery monomer,introducing the basic terminology of lithium-ion battery.(3)Designing a battery pressurization device to carry out pressure experiments,analyzing the influence of pressure on battery life through different groups of pressure experiments,finding out the optimum pressure field of the lithium-ion battery,and exploring the similarities and differences between the cycle life of the battery under this optimum pressure and that of the normal non-pressurized battery,and comparing and analyzing the charge-discharge curves of the pressurized battery in different life periods.(4)Explore the change of battery expansion during charging and discharging and the change of pressure in the whole cycle life of battery,and analyze the reasons of battery expansion from the angle of the change of battery plate and gas swell.(5)Learn the design principle of battery module and the choice ofbattery series and parallel connection,and try to design battery module.Experiments show that proper pressure can not only keep the discharge capacity of lithium batteries good,but also slow down the decline of battery capacity and prolong the life cycle of batteries.Experiments show that during the battery cycle,the battery expands during charging and shrinks during discharging.The overall expansion of the battery is mainly caused by the negative electrode.For the cell monomer used in this experiment,the suitable pressure can prolong the battery life by more than 38.9%.