Why do lithium batteries use aluminum for their positive terminals and nickel for their negative terminals?
Why do lithium batteries use aluminum for their positive terminals and nickel for their negative terminals?
1. Both are conductive, soft, easy to stick together, inexpensive, and can form an oxide film on the surface.
2. Copper/nickel oxide is composed of semiconductors, with conductive characteristics, and the thickness of the oxide is too thick, so it has a high impedance, and aluminum oxide is a kind of insulating material, it can not conduct electricity, but it is very thin, it can use its channel action to conduct, if the oxide layer is too thick, its conductivity will decline, and even lead to insulation. Generally, the surface of the collector should be cleaned prior to use to remove dirt and to remove thicker layers of oxidation.
3. With high positive potential and thick aluminum film, can effectively prevent the oxidation of the concentrated flow. The oxidation layer of copper/nickel is relatively loose, in order to avoid oxidation, it is best to low potential, and Li is not easy to form a lithium alloy with Cu/Ni at low potential, but if copper/nickel is oxidized in large amounts, the lithium reaction between Li/ cu/Ni, but at low potential, aluminum foil can not be used as a negative material, which will lead to the alloying of LiAi.
4. The composition of the concentrate is very demanding. The impurity of aluminum will cause the film to be not dense, resulting in pitting, and more seriously, the surface layer of aluminum is destroyed, resulting in the formation of LiAi alloy.
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