Study On Thermal Behavior Of Lithium-Ion Battery In The Formation Process And Design Of Cooling Structuer

Due to the advantages of lithium-ion battery抯high specific energy, long cycle life, and small environmental pollution, it is becoming the mainstream power source of new energy vehicle. Lithium-ion power battery is the key part of automobile, the charging and discharging performance and reliability will affect the cost and performance of a vehicle directly, A lot of heat is produced in the electrochemical reaction of times charging and discharging during formation process. Therefore the cooling quality of battery and battery surrounding situation in the process of charging and discharging become the key factor affects the formation effect of lithium battery. Formation unit of actual lithium battery is the research object of this subject, the mechanism of heating and cooling method of lithium battery are researched from two aspects, theory and experiment simulation, and thus to explore the design method of cooling structure.It has important practical significance and application value for the production of lithium-ion battery.The research main contents in this paper can be summarized as follows:1, Surve structure constitutes of lithium-ion battery, the electrochemical principle, formation process, and the heat generating mechanism in the process of lithium battery charging and discharging adequately. Provide a theoretical basis for further theoretical analysis and numerical simulation.2, Thermal effect model of lithium-ion battery is established and the thermal physical parameters of lithium-ion battery is calculated based on the heat transfer and disperse characteristics of lithium-ion battery. Based on the battery heating theory of Bernadi D, lithium battery heating rate model is established and internal heat of battery during formation process is calculated.3, Fluid dynamics simulation of battery pack heating model is analysed by using Fluent software, build lithium-ion battery抯thermal model, set the boundary conditions, caluate the heating temperature field of lithium-ion battery cell and pack in the state of nature. Further analysis the temperature distribution of lithium battery charging and discharging unit. Investigate the effect of space charging and discharging unit on temperature field of lithium battery pack. All of these provide analysis basis for the design of cooling structure.4, From the view of fluid mechanics theory, this paper launch the design of cooling structure. Put forward four kinds of design schemes, which include blowing-in from the top, induced draft from bottom, nearly closed ventilated box, variable cross-section ventilated box. At the same time, applies Fluent to finish the numberical simulation of four cooling structure, complete quantitatively analysis of effect factors of heat efficiency in cooling structure. Finally, the cooling structure抯key parameters are determined accordingly.This paper put forward temperature field simulation and analysis method during formation process of lithium battery, effective mathematical model is established, a variety design and analysis of cooling structure is carried out, these will be the effective design methods and design basis for thermal design during formation process of lithium-ion battery, also be reference for design of the key component of automatic production line of lithium-ion formation...