What are the characteristics of the carbon-coated aluminum foil that major new energy companies have invested in?

First, the advantages of coated carbon aluminum foil

The passivation layer on the surface of aluminum foil in the charge and discharge process can avoid corrosion of the electrolyte, and is often used as a positive collector fluid to match LiCoO2, lithium manganate, ternary materials and LiFePO4, etc., but conventional aluminum foil usually has the following limitations:

Aluminum foil has a certain rigidity, and the contact area between the anode material and the anode material is limited, which affects the internal resistance of the anode sheet.

The bonding strength of aluminum foil with binder and active substance is limited. Due to the constant change of electrode volume in cyclic charge and discharge, the bonding between particle matter is loose and easy to drop powder, which makes the battery capacity and cycle life rapidly decay.

The oxidation decomposition products of the electrolyte have an electrochemical reaction on the surface of the aluminum foil, which leads to and accelerates the corrosion of the aluminum foil.

Therefore, the application trend of high-end batteries, especially power batteries, is that aluminum foil needs to be modified, and the modification methods of aluminum foil mainly include the following points:

Surface treatment (chemical etching, electrochemical etching, DC anodizing, corona treatment);

Conductive coating (surface coated with carbon, graphene coating, carbon nanotube coating, composite coating);

3D porous structure (foam structure, nanoribbon structure, nanocone mechanism, fiber braid mechanism);

Composite modification treatment.

Among them, the surface coating of carbon is a common modification method of aluminum foil.

Carbon coated aluminum foil is a material used for the positive electrode fluid collection of lithium-ion batteries after adding a carbon coating layer on the surface of aluminum foil. The carbon materials in the coating mainly include carbon black, graphite sheet and graphene. After the carbon material powder and certain film forming agent, solvent and auxiliary agent are prepared into a slurry, it is coated on the surface of aluminum foil, and a dense carbon coating layer is formed after drying.

Carbon coated aluminum foil

Compared with the blank aluminum foil, the carbon coated aluminum foil can improve the conductivity of the positive electrode sheet and reduce the internal resistance of the battery. For example, the electrical conductivity of lithium iron phosphate itself is poor, and the lack of a bridge between the optical aluminum foil and the transmission of electrons, after carbon coating on the surface of the aluminum foil, the carbon coating layer can play a bridge role, the positive active substance and aluminum foil tightly bonded, the particles embedded in each other, thereby improving the conductivity of the positive electrode sheet, and ultimately reducing the internal resistance of the battery. In addition, the carbon coating can make the surface of the aluminum foil uniform convex, increase the contact area between the active substance in the electrolyte and the positive collector fluid, so as to transfer electrons faster and collect current when the high current fast charge and discharge, which can improve the battery rate charge and discharge performance, help the lithium battery to improve the use efficiency and adapt to the large rate fast charge.

Its advantages are:

Reduce the interface impedance of fluid collector, reduce polarization, improve cycle life and magnification performance;

Improve the adhesion between the active substance and the collector, reduce the amount of binder and reduce the production cost;

Prevent the collector fluid from being corroded and oxidized, and extend the battery life.

In summary, coated carbon aluminum foil has the ability to improve battery energy density, inhibit battery polarization, reduce battery internal resistance, increase battery cycle life, and is currently mainly used in lithium iron phosphate batteries. In recent years, with the increase of battery energy density requirements, the market demand for carbon-coated aluminum foil has been continuously released, and nearly 90% of power lithium batteries have been used carbon-coated aluminum foil.

In 2020, the global market size of carbon coated aluminum foil reached $224 million and is expected to reach $1.129 billion in 2027, with a compound growth rate (CAGR) of 25.91% from 2021 to 2027.

From the production point of view, China, Japan and other regions are currently the world's largest carbon-coated aluminum foil production areas. At the same time, with the industrial upgrading of the domestic economy, customers have put forward more quality requirements and higher technical indicators for carbon-coated aluminum foil, and the specifications and functional changes are more and more diversified. Enterprises coated with carbon aluminum foil should actively improve product quality, so as to make their products attractive to the market.

The main producers of carbon coated aluminum foil in the market include Showa Denko, Toyo Aluminum, Japan black Lead, Shenzhen Yuqiang, Dingsheng new materials, etc., the world's top five enterprises accounted for nearly 62% of the market, the international market is mostly monopolized by enterprises in the Asia-Pacific region, and the price competition is more fierce, affecting the benign development of the market.

The main consumption areas of carbon aluminum foil are North America, Europe, China, Japan and other countries and regions with industrial development systems. These regions account for more than the majority of the global market. At the same time, Southeast Asian countries such as Malaysia, Indonesia, Thailand and other economies have developed rapidly in recent years, with greater market potential.