Why lithium battery cathode with copper foil the anode aluminum foil?

Source: 2020 - 03 - 28 good tidings hits: why lithium battery cathode with copper foil belt, the anode with aluminum foil on lithium ion batteries, the use of the positive collector of the general solution is aluminum foil, the cathode liquid collector is the copper foil, in order to guarantee the stability of the collector fluid inside the cell, both the purity of 98% or more. Lithium batteries and electric technology constantly open up, whether used for digital products or the batteries of electric cars, we expect the battery energy density is high, as far as possible the weight of the battery is more and more light, and the decline in fluid are the main set the thickness and the weight of the fluid, reduced the volume and weight of the battery from intuitive. Lithium ion battery anode used aluminum foil, the copper foil, for three reasons: one is the copper foil conductive performance is good, quality of a material soft, price is cheap. As we all know, the working principle of lithium-ion batteries that convert chemical energy into electricity is an electrochemical device, so in the process, we need a medium to convert chemical energy into electricity, conducting information need is here. In the general material of speculation, the conductivity of the metal material is the best data, and in metal materials, electrical conductivity cheap is good copper foil and aluminum foil. In general, in the lithium battery, we basically have two kinds of processing methods: winding and laminating method. Related to the winding, the requirements for the preparation of cell has certain flexibility, to ensure the winding sheet does not exist in the brittleness problem, and the metal materials are speculated that the copper foil is a kind of relatively soft metal. Is, after all, considering the preparation cost of batteries, relatively speaking, the price of copper foil is relatively cheap, copper and aluminum in the world is rich in resources. Second, the copper foil is relatively stable in the air. Aluminum react with the oxygen in the air, only in the outside of the form a thin layer of aluminum oxide film, prevent further reaction. The thin oxide film can protect the aluminum electrolyte. Copper in itself is relatively stable in the air, in the monotony of root don't react in the air. Third, the positive and negative potential of lithium-ion batteries should choose to take the positive, of the aluminum foil with the cathode copper foil, not the other way round. The anode potential is high, the copper foil is easy to oxidation under high voltage, high oxidation potential, and aluminum and the aluminum foil surface has a thin layer of oxide film, also have good protection to the interior of the aluminum. These two kind of material has good conductivity, soft texture ( It may also be conducive to bonding) , relatively common and cheap, coupled with the appearance of them can form a layer of oxide film. Li-ion battery with copper foil surface roughness requirement: in terms of collecting liquid, besides its thickness and weight, the production and function of the lithium battery has a lot of influence. Especially the cathode collector fluid, due to the defects of preparation technology, currently on the market of copper foil have single-sided, double-sided, double-sided MAO coarsening. Caused by asymmetric double structure of double coating on the cathode of asymmetry, contact resistance results in uneven double negative capacitance of the release. At the same time, double-sided asymmetric anode coating can also lead to bond strength, yes, double charge-discharge cycle life of anode coating imbalance, thus speeding up the battery capacity attenuation.