Lithium iron phosphate batteries require copper. For lithium-ion batteries, the commonly used positive electrode current collector is aluminum foil and the negative electrode current collector is copper foil to ensure the stability of the current collector inside drums. , the purity of both must be greater than 98%.
As we all know, the working principle of lithium iron phosphate battery is an electrochemical device that converts chemical energy into electrical energy. In this process, a medium is required to transmit the electrical energy converted from chemical energy. Here you need conductive materials. Among ordinary materials, metallic materials are the most conductive materials. Among metal materials, copper foil and aluminum foil are cheap and have good conductivity. InAt the same time, in lithium batteries, there are two main processing methods: winding and rolling. Compared to winding, the pole pieces used to prepare batteries must have a certain degree of flexibility to ensure that the pole pieces do not suffer from brittle breakage and other problems during winding. Among metal materials, copper and aluminum foil are also soft metals. The final step is to consider the preparation cost of lithium batteries. Relatively speaking, copper and aluminum foil are relatively cheap, and the world is rich in copper and aluminum element resources.
2. Copper and aluminum foil are relatively stable in air. Aluminum readily reacts chemically with oxygen in the air, forming a dense oxide film on the surface of the aluminum to prevent further reactions of the aluminum. This thinhe oxide film also has a certain protective effect on the aluminum in the electrolyte. Copper itself is relatively stable in air and practically does not react in dry air.
3. The potential of the positive and negative electrodes of lithium batteries determines whether aluminum foil is used for the positive electrode and copper foil is used for the positive electrode. negative electrode. The potential of the positive electrode is high, and the copper foil is easily oxidized at a high potential, while the oxidation potential of aluminum is high, and the surface of the aluminum foil has a film of dense oxide, which also has a good protective effect on aluminum. inside. Both are used as current collectors because they have good conductivity, are relatively soft (which can also be beneficial for bonding), are relatively common and cheap, and can form a protective oxide filmon their surfaces. Copper foil and aluminum foil have the advantages of good electrical conductivity, formed oxidation protective film, soft texture conducive to bonding, mature manufacturing technology and relatively low price, so they are selected as the main materials for current collectors of lithium batteries. The positive electrode potential of the lithium iron phosphate battery is high, and the oxide layer of the aluminum foil is relatively dense, which can prevent oxidation of the current collector. However, copper will undergo lithium insertion reaction at high potential and is not suitable. for use as a positive electrode current collector. The positive electrode current collector generally uses aluminum foil; while the negative electrode, the potential is low and the aluminum foil can easily form aLow potential aluminum-lithium alloy. The negative electrode current collector generally uses copper. foil, copper foil and aluminum foil are not interchangeable.
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