What are the factors that cause the inconsistency of lithium power lithium-ion battery cell and module parameters?

1) Factors leading to inconsistent parameters of lithium-power lithium-ion battery cells The inconsistency of lithium-power lithium-ion battery cell parameters is a continuous accumulation process. The longer the time, the greater the difference between the parameters of the lithium-ion battery cells. The reason is that the use of lithium-power lithium-ion battery modules is affected by environmental factors, causing the inconsistency of lithium-power lithium-ion battery cell parameters to be gradually amplified, resulting in accelerated performance of some lithium-power lithium-ion battery cells Attenuation, eventually leading to the end of the life of the lithium-power lithium-ion battery module. The factors that affect the inconsistency of lithium-power lithium-ion battery cell parameters are: 1) During the manufacturing process of lithium-power lithium-ion battery cells, due to the instability of the manufacturing process processing level, material accuracy, and purity, the final product performance parameters are inconsistent. . Lithium-powered lithium-ion battery cells processed with different batches of positive electrodes, negative electrodes and electrolytes generally cannot be mixed. Even if the parameters of the lithium-powered lithium-ion battery cells are very consistent during the sorting process, the state of the lithium-powered lithium-ion battery cells after a period of use in the future cannot be guaranteed. Therefore, the current solution is to guard against the use of different batches of positive electrodes. , The negative electrode and the lithium-ion battery cells processed by the electrolyte are mixed for use. Consistency is affected by many aspects such as processing procedures. 2) The processing technology of lithium power lithium-ion battery cells is more complicated. In the entire processing process, the consistency of each process is very important, but the most difficult to ensure consistency is the coating process. , The thickness and averageness of the coating and the activity of the material are not easy to be controlled by mechanical means, and are an important process that causes the difference in lithium-ion battery cells. The differences in the manufacturing process can only be compensated in the sorting process. In the processing of lithium-powered lithium-ion battery cells, even if the batching, pulping, coating, cutting, rolling and other processes are strictly controlled, the standard deviation between batches of products can only be reduced, but the inconsistency cannot be eliminated. (2) Factors that cause inconsistencies in the parameters of lithium-power lithium-ion battery modules. The critical structures of lithium-power lithium-ion battery cells include positive electrode, positive electrode current collector, negative electrode, negative electrode current collector, diaphragm and electrolyte. The inconsistency in performance of lithium-powered lithium-ion battery cells can ultimately be rooted in these components. The inconsistency of lithium-power lithium-ion battery cells will inevitably be transferred to the lithium-power lithium-ion battery module. The importance of lithium-power lithium-ion battery cell sorting will be reflected in the formed lithium-power lithium-ion battery module . Single lithium-power lithium-ion battery cells are welded, clamped, connected in series and parallel to form a lithium-power lithium-ion battery module. The process inconsistency in this processing process will inevitably lead to inconsistencies between the lithium-power lithium-ion battery module and the module. The most intuitive sign is the inconsistent internal resistance of the lithium-power lithium-ion battery module. 1) In the process of forming the lithium power lithium ion battery module, the inconsistent welding process can easily cause the difference in welding resistance. The internal resistance of the lithium-power lithium-ion battery cell is of the order of several or ten milliohms. The slight inconsistency in the welding resistance during the welding process is unacceptable for the lithium-power lithium-ion battery module. 2) The size, connection method and surface solution of the copper bars or high-voltage wires used for the connection between the lithium-power lithium-ion battery modules and the modules will also affect the consistency of the lithium-power lithium-ion battery modules. The main concern is the internal resistance of the current lithium-powered lithium-ion battery module. 3) Lithium-powered lithium-ion battery modules with different connection methods (screw connection, crimping or welding) have different effects on the consistency of lithium-powered lithium-ion battery modules in use. In addition to considering the manufacturability of production, the influence of connection resistance must also be considered. If the connection point is welded, if the surface solution is not done well, oxidation corrosion occurs, and its resistance will naturally increase. For solder joints without corrosion, the resistance will be different from that of solder joints with corrosion. (3) Factors that cause inconsistencies in the parameters of the lithium-power lithium-ion battery modules are put into use. After the lithium-power lithium-ion battery modules are put into use, the cell parameters of each single-cell lithium-power lithium-ion battery in the lithium-power lithium-ion battery module Affected by differences in electrolyte density, temperature and ventilation conditions, degree of self-discharge and charge-discharge process. Because the position of the lithium-powered lithium-ion battery cell in the lithium-powered lithium-ion battery module is different, the lithium-powered lithium-ion battery cell that is wrapped in the center of the lithium-powered lithium-ion battery module is different from the lithium-powered lithium-ion battery cell. The single lithium power lithium-ion battery cell in the outermost layer of the ion battery module has very different heat dissipation conditions. Before the thermal equilibrium is reached, the temperature conditions of different single-cell lithium-power lithium-ion battery cells are different. 1) If the lithium-power lithium-ion battery pack is installed in different locations, the difference in the ambient temperature will have different effects on the consistency of the lithium-power lithium-ion battery module. Due to the difference in the distance from the external environment and the distance from the heat source, the temperature conditions of the lithium-power lithium-ion battery module at different positions in the lithium-power lithium-ion battery pack will be different. 2) The different positions of lithium-power lithium-ion battery cells relative to the current collector copper bars will cause different heat dissipation conditions between each other, resulting in inconsistencies in the thermal environment temperature of the lithium-power lithium-ion battery cells. 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