Li-ion battery positive and negative electrode

Lithium-ion batteries are generally divided into the main four major parts are cathode materials, anode materials, isolation membranes and electrolytes. However, in addition to the main four parts, the storage of positive and negative materials is an important component of lithium batteries. basic information of the set fluid

For lithium-ion batteries, the usual use of the positive collector is aluminum foil, negative collector fluid is copper foil, in order to ensure the stability of the set fluid in the battery, both purity requirements above 98%. With the development of lithium-ion technology, whether it is used for digital products lithium battery or electric vehicle battery, we all hope that the battery energy density as high as possible, the weight of the battery is more and more light, and in the set of fluid this is the most important to reduce the thickness and weight of the set fluid, from the intuitive to reduce the size and weight of the
copper Foil Thickness requirements

With the rapid development of lithium battery in recent years, the development of the collector fluid is very fast. Positive aluminum foil from the previous few years of 16um down to 14um, and then to 12um, now many battery manufacturers have been mass production using 10um aluminum foil, and even used to 8um. And the cathode with copper foil, due to its good flexibility of copper foil, its thickness from the previous 12um to 10um, then to 8um, to the present there is a large number of battery manufacturers with 6um, and some manufacturers are developing 5um/4um are possible to use. As the lithium battery for the use of copper foil purity requirements, the density of the material at the same level, with the development of the thickness of the lower, its surface density is correspondingly reduced, the weight of the battery is also more and more small, in line with our demand for lithium batteries.
Why use copper foil for cathode

First, copper foil conductive good, soft texture, low price. As we all know, the working principle of lithium battery is a kind of electrochemical device that converts chemical energy into electric energy, so in this process, we need a kind of medium to transfer the energy of chemical energy conversion, here need conductive material. In ordinary materials, metal materials are the best conductive materials and in the metal materials cheap conductivity and good is the copper foil and aluminum foil. At the same time, in the lithium battery, we mainly have two kinds of winding and laminated processing methods. Relative to the winding, the need for the preparation of the battery of the pole piece has a certain degree of softness, in order to ensure that the pole piece in the winding without brittle fracture and other problems, and the metal material, copper foil is a soft texture of the metal. The last is to consider the cost of battery preparation, relative to the price of copper foil relatively cheap, the world's copper and aluminum resources rich.

Second, copper foil in the air is relatively stable. Aluminum can easily react with the oxygen in the air, creating a dense oxide film on the surface of the aluminum, preventing further aluminum reactions, and the thin oxide film has a certain protective effect on aluminum in the electrolyte. Copper in the air itself is relatively stable, in the dry air basically does not react.

Third, the positive and negative electrode potential of lithium battery to determine the positive aluminum foil, cathode with copper foil, rather than vice versa. High positive potential, copper foil at high potential is easily oxidized, and aluminum oxidation potential is high, and aluminum foil surface has a dense oxide film, the internal aluminum also has a good protective effect.

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