1, moisture Excessive moisture will cause side reactions with the positive and negative active materials, destroying its structure and affecting the cycle. At the same time, too much moisture is not conducive to the formation of SEI film, but trace amounts of water are difficult to remove while trace amounts of water are also The performance of the battery core can be guaranteed to some extent. 2, positive and negative compaction The positive and negative compaction is too high, although the energy density of the cell can be increased, but the cycle performance of the material is also reduced to a certain extent. From the theoretical analysis, the greater the compaction, the greater the structural damage to the material, and The structure of the material is the basis for ensuring that the lithium ion battery can be recycled; in addition, it is difficult to ensure a high liquid holding capacity for the cell with a high positive and negative compaction, and the liquid holding amount is a normal cycle of the cell or more. The basis of the cycle. 3. Objective conditions of testing During the test, the charge and discharge rate, the cut-off voltage, the charge cut-off current, the overcharge and overdischarge during the test, the temperature of the test room, the sudden interruption during the test, the contact resistance of the test point and the cell, etc., may be more or more Or less affect the cycle performance test results. In addition, different materials are sensitive to the above objective factors. Uniform test standards and understanding of commonality and important material characteristics should be sufficient for daily work. 4, the excess of the anode The reason for the excess of the negative electrode is that in addition to the influence of the first irreversible capacity and the deviation of the coating film density, the influence on the cycle performance is also considered. For the lithium cobaltate plus graphite system, the negative electrode graphite becomes the "short plate" in the cycle. "One side is more common. If the anode is not enough, the battery may not be decomposed before the cycle. However, after several hundred cycles, the structure of the positive electrode changes little but the structure of the negative electrode is severely damaged and the lithium ion provided by the positive electrode cannot be completely received. Lithium causes a premature decline in capacity. 5, coating film density Considering the effect of membrane density on the cycle of a single variable is almost an impossible task. The inconsistency of the membrane density either brings about the difference in capacity, or the difference in the number of layers of the core winding or the lamination. In the case of cells, reducing the film density is equivalent to increasing the number of layers or layers of winding or lamination. The corresponding diaphragm can absorb more electrolyte to ensure circulation, and the cell can be increased in consideration of a thinner film density. The rate performance, pole piece and bare cell baking will also be easier to remove water. Of course, too thin film density coating error may be more difficult to control, large particles in the active material may also be coated, rolled The pressure has a negative impact, and more layers mean more foil and diaphragm, which means higher cost and lower energy density, so the balance needs to be evaluated. 6, material types The choice of materials is the first factor affecting the performance of lithium-ion batteries. The materials with poor cycle performance are selected. The process is reasonable and finished, and the cycle of the cells is inevitably guaranteed. The better materials are selected, even after the follow-up. There are some problems in the process, and the cycle performance may not be too ridiculous. From the material point of view, the cycle performance of a full battery is the cycle performance after the positive electrode is matched with the electrolyte, and the cycle after the negative electrode and the electrolyte are matched. The performance of the two, the worse one, the material's cycle performance is poor, on the one hand, the crystal structure changes too fast during the cycle and can not continue to complete lithium intercalation, on the one hand may be due to activity The material and the corresponding electrolyte cannot form a dense and uniform SEI film, causing the active material and the electrolyte to react prematurely, causing the electrolyte to be consumed too quickly and affecting the circulation. In the design of the battery core, if one pole confirms the selection of materials with poor cycle performance, the other pole does not need to select materials with better cycle performance and waste. 7, the amount of electrolyte There are three main reasons for the lack of electrolyte solution, one is that the amount of liquid injection is insufficient, and the other is that although the amount of liquid injection is sufficient, the aging time is not enough or the positive and negative electrodes are not fully immersed due to high compaction, etc. The electrolyte inside the circulating cell is consumed. Thirdly, the microscopic representation of the matching of the positive and negative electrodes, especially the negative electrode and the electrolyte, is the formation of dense and stable SEI, while the visible performance of the right eye is not only the consumption rate of the electrolyte during the cycle, but also the incomplete SEI. On the one hand, the membrane cannot effectively prevent the negative electrode from reacting with the electrolyte to consume the electrolyte. On the other hand, in the defective portion of the SEI film, the SEI film is regenerated as the cycle progresses, thereby consuming the reversible lithium source and the electrolyte. Whether it is a cell with hundreds or even thousands of cycles or a battery with dozens of dips, if the electrolyte is sufficient before the cycle and the electrolyte has been consumed after the cycle, it is possible to increase the amount of electrolyte. To the extent that it improves its cycle performance. Fully Automatic Washing Machine
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The battery we pay most attention to is the lithium-ion battery, because the battery of our mobile phone, pad, and notebook is a lithium-ion battery, and its battery life has always been a key direction of enterprise research. The importance of cycle performance to lithium-ion batteries is not to be said. On a macro level, longer cycle life means less resource consumption. Therefore, the factors affecting the cycle performance of lithium-ion batteries are related to each lithium battery industry. People have to consider the issue.