Hello Everyone,
I am currently optimizing the production process for the battery packs.
I would like to know how the great the increase in contact resistance with an aluminium oxide layer on the battery terminals?
I am going to use laser welding to bind the terminals together. If I file the terminal just before the welding to remove the top layer, will it make any difference? how quick is the passivation of aluminium?
Any literature would be very helpful. Is it possible to find out experimentally using the Impedance spectroscopy?
Thanks in advance.
The first layer of aluminum oxide, 1.5 nm - 2 nm, is formed instantaneously as its formation depends only on the arrival of oxygen to the surface of Al. After that, the oxidation depends on the arrival of the oxygen as well as its diffusion through the existing oxide layer. The later growth, up to 4.5 nm, takes several days.
Based on that, If you file the terminal just before the welding then it is expected to obtain only the first layer.
Bulk aluminum oxide is an insulator. Therefore its bandgap and electrical resistivity are very high. However, when Al2O3 is present as a thin layer on Al substrate, its electrical properties will be different from that of bulk. Still, you can expect a high electrical resistance. Therefore, you have to remove this layer before welding by abrading with sand papers or filing. Air formed oxide layer does not thicken that fast. Otherwise welding of aluminum will be very difficult. Impedance spectroscopy will be helpful to determine the resistance of the oxide layer, but you are going to change the interfacial condition during the experiments.
Aluminum oxid (Al2O3) represents an insulator with high value of electrical resistance 1x1014 Ω·cm. Al2O3 is created in very fine (a few nanometers) layer due to chemical reaction of aluminium with air oxygen. The battery terminal (e.g. in cars) should be protected against aluminum oxide ocurence with special grease. Al2O3 presence leads to a high resistance contact at the terminal reducing the performance of the battery.
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