Let's take a look at some methods of material modification, here are mainly borrowed from Shanghai Shanshan's material improvement concepts to learn with you.
This is mainly for high energy density design ideas. From two aspects to improve, one is to improve the degree of graphitization, which has two benefits, can improve the gram capacity and improve the compaction of the material; The second is that the surface is evenly coated, which reduces the active point, reduces the consumption of lithium ions, and improves the first effect.
By reducing the rebound of the electrode and the change in the thickness of the whole battery, the energy density can also be improved. There are two options here, one is to refine the particles to reduce the swelling, and the other is to carry out granulation to achieve the effect of reducing the overall stress through the stress relief between different particles. However, the feasibility of the first solution is not very high, because when the particle size is reduced, the bulk density of the material and the compaction density of the final electrode will be reduced.
Of course, in the actual application process, often the product needs a balanced material, so the high-end artificial graphite that is currently used more is this scheme, using secondary particles and refining primary particles. "Charge for 5 minutes, talk for 2 hours", I believe everyone will be familiar with it. This can be achieved through fast-charging batteries, so let's see how graphite can achieve it.
Let's take a look at the effect, this is the carbon coating made of the surface. As mentioned earlier, hard carbon and soft carbon materials have better rate performance, because the surface treatment effectively increases the transmission speed of lithium ions.
If the particle size is smaller, the transmission path is shorter for the lithium ions inside the material, and it is also convenient to quickly embed and come out, and at the same time, the end face of the secondary particles is more, which is also more conducive to the activity of lithium ions.
