What are lithium battery pack cells? How to evaluate the technical level of lithium battery cells? The battery cell is an important part of the lithium battery pack assembly. A lithium battery pack that has been delivered to the market through safety inspection by the manufacturer usually consists of several parts such as the battery cell, management unit and casing. consist of.

　　What is a lithium battery pack cell?

　　Lithium battery pack cells refer to a single electrochemical cell containing positive and negative electrodes and are generally not used directly. It is mainly composed of positive electrode material, negative electrode material, electrolyte, separator and casing. The quality of the battery core directly determines the quality of the lithium battery pack.

　　Lithium battery pack cell types

　　There are three types of batteries that are widely used on the market, mainly 18650 batteries, polymer batteries and lithium iron phosphate batteries.

　　1. 18650 battery cell

　　The 18650 type lithium battery refers to a battery with a diameter of 18mm and a length of 65mm. 0 indicates a cylindrical battery. The technology of 18650 battery cells is relatively mature. The battery structure is stable, the specific capacity is high, the overall performance is outstanding, and it can be used in many ranges because of its small size.

　　2. Polymer battery core

　　The difference between polymer cells and traditional lithium-ion batteries lies in the production process. Lithium batteries are wound and soft in size. Polymers are stacked and have a stiffer shape. For polymer and lithium batteries of the same volume, the capacity of polymer is larger, about 30% higher. And safer, with less risk of explosion. long lasting.

　　3. Lithium iron phosphate battery

　　Lithium iron phosphate battery cells, in terms of material composition, are more common in resources on the earth. The P-O bond in the lithium iron phosphate crystal in the battery core is stable and difficult to decompose. Even at high temperatures or overcharge, it will not collapse and generate heat or form strong oxidizing substances like lithium cobalt oxide, so it has good safety.

　　What is the technical level of lithium battery pack cells?

　　In terms of the technical level of lithium batteries, there is still a big gap between domestic and foreign countries. This time, the editor will analyze the technical level of domestic lithium battery cells from the three packaging systems of lithium battery pack cells.

　　The three packaging systems of lithium batteries are square shell, cylindrical, and soft pack. These three packaging systems are the most widely used methods around the world.

　　1) Square shell

　　In terms of square case batteries, the energy density of domestic companies has reached 240Wh/kg, and there are plans to increase the energy density of lithium batteries to 300Wh/kg by 2020.

　　Internationally, some foreign companies produce lithium batteries that are 10Wh/kg higher than domestic companies, and their energy density has reached 250Wh/kg. However, industry insiders speculate that the cathode material used in this higher energy density lithium battery may be different from the materials used in China.

　　Although there is still some gap between domestic companies and foreign companies in terms of energy density, this gap is not too big, and the selection of cell materials between the two may be different.

　　If you simply want to compare technical levels, the energy density between square case batteries of the same specification is more comparable. So from a technical perspective alone, there may not be much difference between domestic and foreign technologies.

　　2) Cylindrical

　　In terms of cylindrical batteries, the energy density of lithium batteries produced by domestic manufacturers has reached 240Wh/kg, and the foreign technical level has reached 250Wh/kg.

　　Compared with foreign countries, there is a 10Wh/kg gap in energy density between cylindrical batteries and square-shell batteries. However, regarding this gap, domestic companies are also trying their best to catch up. I believe that it is not far away to catch up with the technical level of foreign lithium batteries.

　　3) Soft bag

　　If the energy density of soft-packed batteries needs to be compared with batteries in other packaging methods, then in terms of technology, soft-packed batteries will definitely be able to reach a high density level of 200Wh/kg faster.

　　Due to the green and environmentally friendly materials of lithium batteries and their advantages in energy density, they have been developed consistently at home and abroad, and research on their technology will continue to improve.

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