Briefly describe several major factors affecting the cycle life of lithium batteries

1. Data type: The choice of data is the top element that affects the function of lithium batteries. If the material with poor circulation function is selected, no matter how reasonable the process is and no matter how perfect it is made, the circulation of the battery cell will not be guaranteed; if the better material is selected, even if there are some problems in the subsequent production, the circulation function may not be bad. Too outrageous (Lithium cobalt oxide is only about 135.5mAh/g and lithium-evolved battery cell, 1C although more than 100 dives but 0.5C, 500 times more than 90%; after a battery is disassembled, the negative electrode has black graphite particles The battery cell, the circulation function is normal). 2. Positive and negative electrode compaction: The positive and negative electrode compaction is too high, although it can increase the energy density of the battery, but it will certainly reduce the circulation function of the material to a certain extent. From a theoretical analysis, the greater the compaction, the greater the damage to the structure of the material, and the structure of the material is the basis to ensure that the lithium battery can be recycled; in addition, it is difficult to ensure the higher the positive and negative poles of the batteries. The liquid retention capacity of the battery is the basis for the battery cell to complete the normal cycle or more cycles. 3. Moisture: Excessive moisture will cause side reactions with positive and negative active materials, damage its structure and affect circulation. At the same time, too much moisture is not conducive to the formation of SEI film. But together with the trace amount of water that is difficult to remove, the trace amount of water can also ensure the function of the battery to a certain extent. Unfortunately, Wenwu’s personal experience in this area is almost zero, and I can’t say much. Everyone is interested to search the forum for information on this topic, there are still quite a few. 4. Coating film density: It is almost an impossible mission to consider the influence of film density on the cycle of a single variable. The inconsistency of the film density of lithium battery equipment either brings about a difference in capacity, or a difference in the number of layers of battery core winding or lamination. For batteries of the same type, same capacity and the same material, decreasing the film density is equivalent to adding one or more layers of winding or lamination, and the corresponding added barrier can absorb more electrolyte to ensure circulation 5, excessive negative electrode : The reason for the excessive negative electrode is to consider the influence of the first irreversible capacity and the density error of the coating film, and the influence on the cycle function is also a consideration. Regarding the lithium cobaltate plus graphite system, it is more common for negative graphite to become the weaker side of the cycle. If the negative electrode is lacking enough, the battery cell may not release lithium before cycling, but the structure of the positive electrode changes little after hundreds of cycles, but the structure of the negative electrode is severely damaged and cannot completely accept the lithium ions supplied by the positive electrode, thereby forming an overcapacity. Drop early. 6. Electrolyte volume: There are three reasons for the lack of electrolyte volume to affect the circulation. One is the lack of injection volume, and the second is that although the injection volume is sufficient, the aging time is not enough or the positive and negative electrodes are formed due to excessive compaction. Insufficient liquid, and thirdly, the internal electrolyte of the circulating cell is consumed. The lack of injection volume and the lack of liquid retention capacity have previously written 'Impact of Electrolyte Lack on Cell Function7. The objective conditions of the test: charge-discharge rate, cut-off voltage, charge cut-off current during the test, overcharge and over-discharge during the test, test room temperature, sudden suspension during the test, test point and internal resistance of the battery's touch Such external factors will more or less affect the results of the circulatory function test. In addition, different materials have different sensitivity to the above objective factors. Consistent test specifications and knowing the characteristics of common and important materials should be enough for daily operations. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete.