Lithium ion battery discharge cycle heating characteristics of the study

Source: 2020 - 04 - 12 then hits: lithium-ion battery discharge cycle heating characteristics of the thermal characteristics of the lithium ion battery of battery thermal management system development has the vital significance. By numerical method in the process of lithium-ion battery discharge micro thermal characteristics are studied, and a solid electrolyte of lithium battery discharge cycle ( SEI) Movies and ohm heat change law were analyzed, the results show that the lithium battery in the high rate discharge ( > 5度) , the heat generated by the SEI film is an important part of a lithium battery heating; With the progress of the discharge cycle, lithium battery positive particles on the surface of the SEI linear pattern thickening, lead to SEI resistance increasing. Discharge temperature is higher, the faster the lithium battery cathode SEI thickening, the faster capacity declined. 0 foreword lithium ion battery has ratio can, discharge voltage, and the advantages of good cycle life, is considered to be pure electric vehicles ( EV) And hybrid cars ( HEV) One of the best energy storage device. Is to guarantee the safe operation of the high power lithium battery thermal management system of one of the core technology. Too high temperature will lead to the lithium battery electrolyte on the surface of ( SEI) The destruction of the membrane, so as to shorten the service life of the battery, can lead to security issues such as battery explosion. So the thermal characteristics of the lithium battery in complex conditions is the basis of the development of thermal control technology, the power battery thermal management system development is of important scientific significance. At present, mainly through the numerical simulation and experimental analysis to study the thermal characteristics of lithium-ion batteries. Proposed by conan Doyle and battery energy equation in the electrochemical model proposed bernardi, scholars at home and abroad, on the basis of more than lithium batteries thermoelectric coupling model is developed, using thermoelectric coupling model calculation such as lithium pool in discharge characteristics of different temperatures, and the analysis of the influence of temperature and the related parameters of lithium battery discharge characteristics. Thermoelectric coupling model is used to calculate the winding temperature of lithium ion batteries. J。 v。 azquez - Arenas and others using thermoelectric coupling model to simulate square lithium ion battery, battery temperature on the discharge characteristics are studied and the influence of lithium ion concentration distribution, quantitative analysis of the influence of different heat source on the battery calorific value. At present, the study of thermal characteristics of lithium batteries mostly using thermoelectric coupling model, and less consideration to the lithium battery capacity degradation problem. In the process of lithium battery charge and discharge cycle, the cathode film will gradually thickening due to deposition, lithium battery internal resistance increases, resulting in significant increase in the heating rate of lithium battery. In the lithium battery thermoelectric coupling model, considering the circular attenuation problem, analysis the influence of temperature on the lithium battery capacity attenuation. But the model and the research results of the proposed model applies only to research the model of specific lithium-ion batteries, the lack of generality. Battery of thermoelectric scale model is applied in this article, considering the attenuation in the process of cell cycle SEI changes affect cells generate heat. Lithium battery cycle are analyzed in detail the heat in the process of change and the influence of temperature on battery life, the following conclusions: 1. In the process of high-speed lithium-ion batteries discharge ( > 5c) , the heat generated by the SEI film is an important component of the lithium battery to generate heat, accounting for more than 14% of the total quantity of heat; 2. With the development of the discharge cycle, lithium battery cathode SEI gradually thickening, the higher the discharge temperature, SEI grow faster, the faster the capacity decline; 3. The thickness of the SEI and resistance increases linearly with the increase of the number of discharge). 4. Lithium battery discharge SEI generated in the process of heat and temperature rise will increase gradually with the increase of discharge cycles.