Several Factors Affecting The Cycle Performance Of Lithium Titanate Batteries

Several factors affecting the cycle performance of lithium titanate batteries

Needless to say, the importance of cycling performance on lithium titanate batteries. From a macro perspective, longer cycle life means less resource consumption. Therefore, the factors that affect the cycle performance of lithium batteries are issues that everyone related to the lithium battery industry has to consider. The following lists a few factors that may affect the battery cycle performance for your reference.

Types of materials: The choice of materials is the first factor that affects the performance of lithium batteries. If the material with poor cycle performance is selected, the process is reasonable and the production is perfect, and the cycle of the battery core will inevitably be unable to be guaranteed; if you choose a better material, even if there are some problems in the subsequent manufacture, the cycle performance may not be poor Too outrageous (Lithium cobaltate is only about 135.5mAh / g and the lithium is discharged. Although 1C dives more than 100 times, it is 0.5C and 500 times more than 90%; after the battery is disassembled, the negative electrode has black graphite particles ), The cycle performance is normal). From a material point of view, the cycle performance of a full battery is determined by the poorer of the cycle performance after matching the positive electrode and the electrolyte and the cycle performance after matching the negative electrode and the electrolyte. The cycle performance of the material is poor. On the one hand, the crystal structure may change too fast during the cycle to continue the lithium insertion and delithiation. On the one hand, the active material and the corresponding electrolyte cannot generate a dense and uniform SEI film. Premature side reactions with the electrolyte cause the electrolyte to be consumed too quickly and affect circulation. In the design of the cell, 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, which is wasteful.

Positive and negative electrode compaction: The positive and negative electrode compaction is too high, although it can improve the energy density of the cell, 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 damage to the structure of the material, and the structure of the material is the basis for ensuring that the lithium battery can be recycled; in addition, the battery cells with higher positive and negative electrode densities are difficult to guarantee higher The liquid retention capacity is the basis for the battery cell to complete the normal cycle or more cycles.

Moisture: Excessive moisture will cause side reactions with the positive and negative active materials, destroy their structure and affect circulation. At the same time, too much moisture is not conducive to the formation of SEI film. However, while trace amounts of water are difficult to remove, trace amounts of water can also ensure the performance of the battery cell to a certain extent. Unfortunately, Wen Wu's personal experience in this area is almost zero, and he can't say much. If you are interested, you can search for information on this topic in the forum. There are still many.

Coating film density: A single variable considering the effect of film density on circulation is almost an impossible task. The inconsistency of the film density will either bring about a difference in capacity, or a difference in the number of cell windings or lamination layers. For batteries of the same model, same capacity and same material, reducing the membrane density is equivalent to adding one or more layers of winding or lamination. The correspondingly increased separator can absorb more electrolyte to ensure circulation. Considering that the thinner film density can increase the rate performance of the cell, the baking and dewatering of the pole piece and the bare cell will also be easier. Of course, the error of the thin film density coating may be more difficult to control. The large particles may also have a negative impact on coating and rolling. More layers means more foils and separators, which in turn means higher costs and lower energy density. Therefore, the evaluation also needs to be balanced.