Why is aluminum foil used for the cathode?

It is mainly divided into three aspects. The first is the electrochemical aspect. As a metal material, aluminum has a middle activity. It will form an aluminum oxide protective film in the air, which has high electrochemical potential and good corrosion resistance; secondly, in terms of mechanical properties , easy to process, good mechanical strength, weldable and riveted, and good thermal and electrical conductivity; again in terms of cost, the reserve is large, the cost is low, it is not a heavy metal, and it is not a strategic resource; therefore, it has been used as a collector of cathode electrodes for so many years.

2) Inspection of aluminum foil: The inspection of incoming materials by general battery companies includes outer packaging, appearance, thickness, width, areal density, material, welding performance, tensile strength, elongation, etc., depending on the thickness and material of aluminum foil. There are internal testing standards, and the testing is relatively simple, so I won’t go into details here.

3) The technological development of aluminum foil: With the improvement of the energy density of power batteries, the aluminum foil as the current collector is getting thinner and thinner, so it is required to have lower impurity content, less self-discharge, better thickness uniformity, Higher surface tension, better bonding performance, thinner thickness, higher strength, higher conductivity, suitable elongation and other requirements. At the same time, in order to increase the content of active substances, aluminum foil surface coating technology It is also developing very quickly. The following will briefly introduce these new technologies.

A. Coating technology: The use of functional coatings for surface treatment of battery conductive substrates is a breakthrough technological innovation. Carbon-coated aluminum foil is to coat dispersed nano-conductive graphite and carbon coated particles uniformly and delicately On aluminum foil. It can provide excellent static electrical conductivity, collect the micro current of the active material, which can greatly reduce the contact resistance between the material and the current collector, and can improve the adhesion between the two, which can reduce the use of adhesives In turn, the overall performance of the battery is significantly improved.

B. Porous aluminum foil: With the development of technology, porous aluminum foil technology has also emerged, which can carry more active materials and make the contact between active material particles closer.

As far as the current technology is concerned, porous aluminum foil has not been applied in large quantities, and there are still problems in coating, low tensile strength, rolling press broken tape, and large burrs leading to large self-discharge. Further research and solutions are needed. There are some small soft package data that can significantly increase the energy density, but we believe that distance industrialization is still difficult, and the pre-manufacturing process of lithium-ion batteries needs to be optimized to match this technology.

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