Explore The Profound Knowledge In The Positive And Negative Poles Of The Battery Ears! Did You Know Everything?

Tabs are a raw material for lithium-ion polymer battery products. For example, mobile phone Bluetooth, Bluetooth batteries, and notebook batteries that we use in our daily life all require tabs.

Lithium batteries are divided into positive and negative poles, and the tabs are the metal conductors that lead out the positive and negative poles from the battery. In layman's terms, the ears of the positive and negative poles of the battery are the contact points when charging and discharging, (like We have to breathe through the nose) But this contact point is not the copper sheet we see on the outside of the battery, but a connection inside the battery. The tabs are generally divided into three materials, and the positive electrode of the battery is made of aluminum (Al ) materials, nickel (Ni) is used for the negative electrode, and nickel-plated copper (Ni-Cu) materials are also available. They are all composed of two parts, a film and a metal strip.

So, here comes the question, why use aluminum as the lug for the positive electrode of the lithium battery cell, and nickel for the negative electrode?

1. Both are used as current collectors because of their good conductivity, soft texture (maybe also conducive to bonding), relatively common and cheap, and a layer of oxide protective film can be formed on the surface of both.

2. The oxide layer on the copper/nickel surface is a semiconductor, the electrons are conductive, the oxide layer is too thick, and the impedance is large; while the aluminum oxide on the aluminum surface oxide layer is an insulator, the oxide layer cannot conduct electricity, but because it is very thin, it is realized through the tunnel effect Electronic conductivity, if the oxide layer is thicker, the conductivity of the aluminum foil is extremely poor, or even insulating. Generally, it is better to clean the surface of the current collector before use. On the one hand, it can remove oil stains and thick oxide layer.

3. The positive potential is high, and the thin aluminum oxide layer is very dense, which can prevent the oxidation of the current collector. The thin oxide layer of copper/nickel is relatively loose. In order to prevent its oxidation, it is difficult for lithium to form a lithium intercalation alloy with copper/nickel at low potential. However, if the copper/nickel surface is oxidized in large quantities, lithium will interact with oxidation Copper/nickel undergoes lithium intercalation reaction, while aluminum foil cannot be used as a negative electrode, and lithium-aluminum alloying will occur at low potential.

4. The current collector requires pure composition. Impurity of aluminum composition will lead to incomplete surface film and pitting corrosion, which is more important than the production of lithium aluminum alloy due to the destruction of the surface film.

To sum up, aluminum is used for the positive electrode of the battery, and nickel is used for the negative electrode.

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