As an 18650 Battery Factory, share with you.
The importance of cycle performance to 50ah Lithium Battery need not be said. In a macro perspective, longer cycle life means less resource consumption. Therefore, the factors affecting the cycle performance of lithium-ion batteries are related to the lithium battery industry People have to consider the issue of large-capacity lithium batteries.
SANYO Lithium Ion Battery
Excessive moisture will cause side reactions with the positive and negative electrode active materials, destroy its structure and affect circulation. At the same time, excessive moisture is not conducive to the formation of the SEI film. However, while the trace amount of water is difficult to remove, the trace amount of water is also difficult to remove. Can guarantee the performance of the battery to a certain extent.
2.Positive and negative electrode compaction
Positive and negative electrode compaction is too high, although it can increase the energy density of the battery, but it will also reduce the cycling performance of the material 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 lithium-ion batteries can be recycled.
3. Objective conditions for testing
The external factors such as the charge and discharge ratio during the test, the cut-off voltage, the charge cut-off current, the over-charge and over-discharge during the test, the temperature of the test room, the sudden interruption during the test, and the internal resistance of the contact point between the test point and the cell will all be more A little affect the cycle performance test results. In addition, the sensitivity of different materials to the above-mentioned objective factors varies, and unified testing standards and understanding of commonalities and characteristics of important materials should be sufficient for daily work.
4.The negative electrode is excessive
The reason for the excess of the negative electrode is to consider the influence of the first-time irreversible capacity and the density deviation of the coating film, as well as the influence on the cycle performance. For lithium cobaltate plus graphite systems, negative graphite becomes the "short board" side of the cycle. If the negative electrode is not excessive enough, the cell may not precipitate lithium before the cycle, 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 fully receive the lithium ions provided by the positive electrode to cause lithium precipitation, resulting in excessive capacity. Drop large-capacity lithium batteries early.
5. Density of coating film
It is almost impossible to consider the influence of the film density on the cycle with a single variable. Inconsistent film density will either lead to a difference in capacity, or a difference in the number of cells wound or laminated. For cells of the same type, same capacity and material, reducing the film density is equivalent to increasing the number of layers of one or more layers of winding or lamination. The corresponding increase in the separator can absorb more electrolyte to ensure circulation. Considering that a thinner film density can increase the rate performance of the battery cell, the baking and dewatering of the pole piece and the bare battery cell will also be easier.
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