How to improve the capacity density of batteries Lithium - Ion Battery Equipment

How to improve the capacity density of batteries -Lithium - Ion Battery Equipment

Improving the energy density of batteries (limited to capacity batteries) is the first priority in designing batteries.

If the capacity is not enough, no matter how low the unit price is, how good the cycle is, and how high the safety is, the battery that is made may not be interested. So how can we improve the energy density of the battery? It can be considered from several aspects:(Lithium - Ion Battery Equipment)

1. Increase the performance of materials that contribute to battery capacity;

2. Reduce the volume of materials that do not contribute to battery capacity;

3. Use more advanced production equipment;

4. Improve the manufacturing process conditions and carry out stricter production monitoring;

5. Optimize the miscellaneous items that affect the capacity;

Let's start to discuss the categories separately:

1. Increase the performance of materials that contribute to battery capacity: This is mainly for positive and negative active materials, which is the most direct method to increase capacity density. The main directions include:

①Use larger materials: such as lithium-rich materials for positive electrodes, high-voltage ternary materials, high-voltage lithium cobalt oxide materials, binary materials, etc.; soft carbon and hard carbon for negative electrodes, silicon-tin-based compounds, etc.

② Use positive and negative materials with higher compaction density.

③ Use active substances with better adhesiveness and conductivity: This can reduce the content of adhesives and conductive agents in the dressing, thereby increasing the capacity of the dressing per unit mass; in addition, the amount of adhesives and conductive agents is reduced. Processing properties such as compaction of the active material of the material can also be improved.

④ Use materials with smaller thickness rebound: after the lithium-ion battery is cycled, the thickness will rebound to a certain extent; the design needs to reserve the rebound thickness after the cycle; and when using materials with a smaller thickness rebound (according to what we have seen so far) See, these materials are also materials with good cycle performance), you can transfer the saved space for thickness rebound to the design thickness of the cell, thereby increasing the design capacity of the cell.

⑤Choose a material system with better performance: a single "good positive electrode", "good negative electrode" and "good electrolyte" together cannot guarantee a "good battery". The combination of materials with poor matching will not only reduce the cycle performance of the battery, but may also affect the rate performance and even the performance of the positive and negative electrodes. Similarly, when the material matching is better, the performance, cycle, and expansion rate of the battery will be affected. The performance may be improved.

With the increasing maturity of lithium-ion battery material technology, the potential of common lithium cobalt oxide and graphite has almost reached its limit. In the future, if other mature systems can be produced, it will have a revolutionary impact on the energy density improvement of lithium-ion batteries!

2. Reduce the volume of materials that do not contribute to battery capacity: This item is more complicated, mainly including: using thinner aluminum-plastic film, using thinner battery separator, using thinner tabs, and using thinner copper foil and aluminum foil, use thinner transparent tape, etc.

It can be seen that the improvement in this area is basically based on "thin". Under the limited volume, the reduction of the volume of the aluminum-plastic film, diaphragm, etc., which does not directly contribute to the capacity, means the increase of chemical substances that can provide capacity, thereby increasing the capacity of the cell.

However, when these materials are thinner, their mechanical strength and safety performance will be affected; on the one hand, auxiliary material manufacturers are required to reduce the volume without substantially reducing the material properties; Manufacturing parameters and even equipment (for example, thinner aluminum foil means higher roll elongation coefficient and increased probability of fragmentation during coating and roll pressing; thinner diaphragm has higher risk of short circuit rate; thinner aluminum plastic The membrane is more prone to pin breakage; thinner tabs will reduce the rate capability of the battery, etc.).

Replacing these thinner materials requires a lot of certification from the battery factory. If the number of trial production is too small, it is impossible to accurately obtain statistical data. If the problem is too large, it will cause waste. Compared with improving the performance of active substances, reducing the content of inactive substances seems to have more ideas, and the aspects involved are equally broad.




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