The thickness of laser drilled microporous copper foil is 8 μ m~12 μ m (the copper foil used in 3C digital batteries is 6-7 μ m), and the thickness of aluminum foil is 12 μ m~20 μ m

The method to improve the specific energy of batteries is to use higher capacity positive and negative electrode materials, thinner separator paper, thinner copper foil and aluminum foil to minimize other auxiliary additives as much as possible.

At present, the thickness of copper foil used in the production of lithium-ion batteries is 8 μ m~12 μ m (copper foil used in 3C digital batteries is 6-7 μ m), and the thickness of aluminum foil is 12 μ m~20 μ m. As a positive and negative electrode conductive substrate, it accounts for 15%~20% of the weight of lithium-ion batteries. How to further reduceCopper aluminum foilWeight ratio, increase specific energy? Therefore, under such environmental stimuli, microporous copper foil and aluminum foil were born:

Advantages of aluminum foil laser micro hole:

For foils of the same specifications, microporous foils with a porosity of 17% reduce weight by 17%; The surface density is the same, but the positive and negative compaction increases (some materials fill the pores).

2. Effectively improve the rate performance of lithium batteries; For traditional foil lithium batteries, the migration of lithium ions diffuses through the two-dimensional direction of the foil to the ear end. After drilling, the diffusion path of lithium ions can be transformed into three-dimensional and all-round penetration. By increasing the contact surface between the positive and negative electrode materials entering the pores and the foil, the migration radius of lithium ions can be reduced and the conductivity efficiency can be improved.

3. Effectively reduce the internal resistance of lithium batteries; Comparison of the same foil materials shows that using punched copper foil and aluminum foil can effectively reduce internal resistance by 8% to 20%.

The permeation efficiency of lithium battery electrolyte after injection can be greatly improved, and the permeation consistency can be guaranteed 100%. For traditional foil lithium batteries, the electrolyte diffuses longitudinally to the center, and after drilling, it exhibits three-dimensional permeation diffusion, completely eliminating the problem of some battery pole piece centers being unable to penetrate. One of the reasons for the lack of consistency in individual batteries within the industry is penetration consistency.

5. Improved the surface adhesion of the foil. The positive and negative surfaces of the positive and negative electrode coating form a working bite state through the material between the pores, greatly reducing the probability of electrode detachment.

6. Improve the bending flexibility of the polarizer, making it more suitable for the application of flexible batteries. (The existing company produces wearable lithium batteries in bulk, with significantly improved performance)

Lithium capacitors, supercapacitors, nickel cadmium, and nickel hydrogen batteries use microporous copper foil, which significantly improves their performance. The reason for not promoting it on a large scale is due to cost issues. Laser drilling has extremely high production efficiency. Expected cost after mass production will be higher than traditionalDouble gloss copper foilThe price increase is limited (estimated to be around 130000/ton).

What are the advantages of using microporous foil materials in lithium-ion batteries? (Taking microporous foil with a porosity of 17% as an example)

1. Directly improving the specific energy of lithium batteries;
Equal standard foil material, microporous foil with a porosity of 17%, weight reduction of 17%; Equal surface density, positive and negative electrode compaction progress (some data is filled into the pores).

2. Useful progress in lithium battery rate function;
Conventional foil based lithium batteries disperse lithium ions towards the electrode ears in a two-dimensional direction through the foil. After the foil is perforated, the dispersion path of lithium ions can be transformed into three-dimensional and all-round penetration, and can be added to the contact surface between the positive and negative electrode materials entering the pores and the foil, reducing the radius of lithium ion migration and improving conductivity. (In my personal opinion, the bottleneck of lithium ion rate function is not the conduction of electrons, but the transfer of power by lithium ions. For example, the application of porous carbon black in rate type batteries is more effective than the experimental effect of non porous conductive agents.)

3. Effectively reducing the internal resistance of lithium batteries;

The comparison of equal foil materials shows that using punched copper foil and aluminum foil together can effectively reduce internal resistance by 8% to 20%.

Theoretical basis, estimation isConductive foil materialThe two-layer effect formed by the addition of positive and negative touch surfaces and the decrease in internal resistance of the foil material itself. (Uncertain)

The Advanced Institute of Technology believes that if the thickness of the coating on the positive and negative electrodes is less than the radius of the micropores in the foil, the internal resistance will increase; otherwise, the internal resistance will decrease. The touch distance between the outermost lithium ions of the coating and the surface of the foil is related to the magnification function. In battery cell design, the higher the surface density, the lower the performance of the magnification function may be. (Looking forward to discussing with professional friends)

4. The moisturizing power of lithium battery electrolyte after writing can fluctuate greatly and ensure 100% moisturizing consistency.

Conventional foil lithium batteries disperse and moisturize the electrolyte from the longitudinal four sides towards the base, and after drilling, it penetrates and disperses in a three-dimensional manner, completely eliminating the problem of some battery electrode bases not being moisturized. In the professional world, one of the factors that have led to poor consistency of individual battery cells is the consistency of moisturizing.