Possible reasons for the attenuation of lithium batteries

Performance degradation: high technical and technological requirements 1. Capacity degradation: equivalent to a decline in the total value of the city's processing, which may be due to the reduction of jobs, the high cost of living or the deterioration of the living environment, and the loss of employed population. Correspondingly, the positive and negative active materials are reduced and the movable Li+ is reduced. 2. New internal resistance: equivalent to low work efficiency in the city, which may be due to high administrative resistance from the government, or high cost of commuting to and from get off work caused by the paralysis of the transportation system, and unreasonable urban planning to live and work farther and farther. That is, the ohmic impedance of the battery increases, the electrical conductivity decreases, and the Li+ movement path deteriorates. 3. High self-discharge: It is equivalent to an increase in the proportion of urban unemployed people, occupying the resources of the city but not creating benefits. That is, Li+ is abnormally depleted, and the internal battery is short-circuited. Safety attenuation: Good quality is required 1. Increased risk of internal short circuit: The diaphragm is damaged or shattered or shrunk by heat. 2. Mechanical deformation and leakage: The gas pressure inside the battery causes the battery to deform and break. Through the above description, we can roughly imagine the reason that causes the battery to attenuate. Then, what are the detailed usage scenarios that lead to the above situation? This article will focus on sorting out the detailed attenuation scenarios and influencing factors of the battery. 1. The positive and negative materials fall off and age. The positive and negative electrodes of the battery will continue to shrink and expand during the continuous charging and discharging process, and the positive and negative materials will fall off on the current collector, so that the number of lattices that can be embedded in Li+ Decrease, thereby affecting the battery capacity. The following figure shows the topological change of the reaction of lithium iron phosphate cathode material. During the charge and discharge process, the cathode material undergoes LiFePo4 and FePo4 conversion. Due to the relatively good overall structural stability, the lattice collapse is not prone to occur. However, the structure of some cathode materials (such as LCO) is easily destroyed, resulting in the loss of active material in the cathode material. 2. SEI film analysis and regeneration quality requirements. In the analysis of battery principle, it is mentioned that the electrolyte will interact with the negative electrode during the formation process, and consume a part of Li+ to form an SEI film; this SEI film can protect the electrode. Above, if the SEI film is stable enough, it can be warned that the electrolyte and the negative electrode material will continue to react. But in reality, the SEI film will be more or less continuously analyzed and regenerated. In this process, the positive and negative materials, electrolyte, and Li+ will continue to be lost (this is also part of the reason for the self-discharge of the battery). Moreover, the continuous thickening of the SEI film will cause the blockage of the diffusion pores on the negative electrode surface, which is not conducive to the diffusion of Li+, which also leads to the continuous increase of the internal resistance of the battery. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: Analysis of the difference between lithium iron batteries and alkaline batteries