Advances in thermal characterization of lithium-ion batteries at different aging stages
The study of the thermal characteristics of lithium-ion batteries at different aging stages is of great significance for the safe operation and control of lithium-ion batteries throughout their life cycle. Firstly, the experimental research progress on the intrinsic thermal parameters and heat production parameters of different aging stages of the battery is sorted out, and the law and internal mechanism of the relevant parameters changing with the aging stage of the battery are clarified; combined with the comprehensive review and analysis of the electric model, thermal model and aging model of the thermal characteristics of lithium-ion batteries, the rule of change of the heat production and temperature rise of lithium-ion batteries with the ambient temperature and multiplicity in the different aging stages is summarized. This work can provide a reference for the study of thermal characteristics and thermal management strategies of lithium-ion batteries throughout their life cycle.
As an important carrier of electric energy storage, lithium-ion batteries have gained rapid development in the field of electric energy storage with their advantages of high specific energy, environmental friendliness, and flexible configuration, but the safety problem is also very prominent. According to incomplete counting, nearly 80 lithium-ion battery-related energy storage safety accidents have been reported worldwide so far in 2017. The study of the thermal characteristics of lithium-ion batteries is an important basis for the safety management of batteries, including the study of battery thermal characteristics parameters and battery heat production sources. Among them, the battery thermal characteristics parameters mainly involve the battery intrinsic thermal characteristics parameters 5542024.4 Vol.48 No.4 (such as specific heat capacity, thermal conductivity) and the battery thermal characteristics parameters (such as entropy coefficient of heat, open-circuit voltage, internal resistance, etc.); the source of the battery's heat generation on the one hand, comes from the battery's ohmic resistance in the process of charging and discharging (including the battery's internal ohmic internal resistance as well as external ohmic resistance of lugs, etc.) and internal resistance of polarization. The source of heat generation comes from the irreversible Joule heat brought by the battery ohmic resistance (including the internal ohmic resistance of the battery and the external ohmic connection resistance such as the lug connection etc.) and polarization resistance during the charging and discharging process on the one hand, and the reversible entropy heat brought by the electrochemical reaction on the other hand. The high or low temperature of the battery will affect the life and safety of the battery, so it is necessary to develop a suitable thermal management strategy to keep the operating temperature of the battery within the appropriate range. However, in the process of battery cycling, the capacity of the battery will continue to decline, accompanied by the aging phenomenon such as the increase of internal resistance, which will not only have an impact on the relevant thermal characteristics of the parameters, but will also cause an increase in the power of heat production of the battery, thus affecting the effectiveness of the thermal management strategy of the battery. In addition, cyclic aging batteries are more prone to self-generated heat and thermal runaway under abnormal temperature shocks, which reduces the safety of batteries. Therefore, the study of the thermal characteristics of lithium-ion batteries at different aging stages is crucial for the development of dynamic thermal management strategies for the whole life cycle of the batteries and the improvement of the safety of the batteries during operation.
