Best thermal conductive paste

Theoretical research on lithium battery conductive agents believes that conductive carbon black is a "point-point" contact model, carbon nanotubes are a "line-point" contact model, and graphene is a "surface-point" contact model. This model allows active material particles to build a "long-range" conductive network on the current collector. The so-called "long-range" conductive network, that is, a better connection structure of the conductive path, has a benefit for the transmission of ions and electrons....

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Best thermal conductive paste, the track of new conductive agents, why are carbon nanotubes ahead of graphene?

We have sorted out the research history, performance characteristics, standard progress and downstream market of graphene and carbon nanotubes, and based on the above objective content, we try to make some subjective judgments.

Before the discovery of graphene, the scientific research community had done sufficient research on the physical structure and electromagnetic thermochemical properties of carbon nanotubes, and various carbon nanotube macroscopic bodies could be prepared. After French scientists first prepared carbon nanotube fibers in 2000, in 2002, Professor Wu Dehai's team at Tsinghua University could prepare 20 cm long carbon nanotube bundles. To this day, the research heat of carbon nanotubes in the scientific research community is still not inferior to graphene.

As a conductive agent, graphene has a steric effect on lithium ions.

Theoretical research on lithium battery conductive agents believes that conductive carbon black is a "point-point" contact model, carbon nanotubes are a "line-point" contact model, and graphene is a "surface-point" contact model. This model allows active material particles to build a "long-range" conductive network on the current collector. The so-called "long-range" conductive network, that is, a better connection structure of the conductive path, has a benefit for the transmission of ions and electrons.

However, in actual application research, it was found that larger-sized graphene as a conductive agent will form a lithium ion steric effect. It is difficult for lithium ions to pass through the graphene hexagonal ring composed of carbon atoms. Therefore, larger-sized graphene will lengthen the lithium ion transmission path and reduce the lithium ion transmission efficiency.

So, what size of graphene is more suitable as a conductive agent? Generally, the size of the positive electrode material is used as an analogy. It is generally believed that when the diameter of the graphene sheet is less than 20μm, the steric effect of lithium ions can be ignored. Therefore, graphene has a steric effect as a conductive agent, which limits its application to a certain extent.

Graphene conductive agents are only suitable for lithium iron phosphate systems and need to be compounded with carbon nanotubes.

In terms of application, as consumers' demand for long driving range and lightweight of automobiles, especially passenger cars, gradually increases, lithium batteries are the development trend, but lithium batteries are not the field where graphene conductive agents are applicable.

Although graphene conductive agents also have the characteristics of excellent conductivity, their application range is limited compared to carbon nanotubes. The commonly used solution in the industry is to use graphene and carbon nanotubes in lithium iron phosphate batteries.

The more common compounding solutions include 3:2 "carbon nanotubes + graphene", 67:30:3 "SP + carbon nanotubes + graphene", etc. It can be seen that the performance improvement of both ternary batteries and lithium iron phosphate batteries cannot be separated from the new conductive agent doped with carbon nanotubes.

From the perspective of new energy vehicles, the parallel development route of lithium iron phosphate and ternary materials in the medium and long term is relatively clear, but the natural conductivity of lithium iron phosphate is worse than that of ternary, so the demand for carbon nanotube conductive agents will be strong.

From the perspective of lithium battery material technology iteration, high nickel positive electrode materials and silicon-based negative electrode materials will become one of the main directions of power battery development. Carbon nanotube conductive agents can improve the poor conductivity of the two. Therefore, in the long run, carbon nanotube conductive agents will gradually become rigid demand.

TANFENG Technology Co., Ltd. is a leader in the field of carbon nanotube conductive agents, and its shipments are growing rapidly. The company has a number of core patented technologies. Compared with its peers, the relevant performance of its carbon nanotube products is at the leading level.

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