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Various classifications of batteries

Broadly speaking, batteries can be divided into three categories: chemical batteries, physical batteries and biological batteries, among which in electric vehicles, the most widely used is chemical batteries, and this issue mainly explains chemical batteries.

Definition of chemical battery: A chemical battery is a device that converts chemical energy into electrical energy. The main part consists of an electrolyte solution and two electrodes, the positive and negative electrodes immersed in the solution. In use, a wire is connected to two electrodes, i.e., an electric current passes through (discharges) and electrical energy is obtained.

Classification: Chemical batteries are currently the most widely used batteries in the field of electric vehicles, and can be divided into two categories: batteries and fuel cells from a structural point of view. AT PRESENT, MOST OF THE MODELS ON THE MARKET USE BATTERIES TO DRIVE THE VEHICLE, SUCH AS NIO ES8, TELA MODEL3 AND SO ON.

storage battery

Status: In the process of technological development, car companies have used different types of batteries, but out of cost and technical considerations. At present, the vast majority of batteries have been eliminated by the market, such as lead-acid batteries, lithium manganese oxide batteries and so on. At present, the mainstream batteries on the market are mainly lithium-ion batteries, and a few car companies use nickel-metal hydride batteries, such as Toyota.

Lithium-ion batteries

The development history of lithium batteries is not very long, but at the beginning of its birth more than 40 years ago, it has become one of the most commonly used battery types in electric vehicles with its advantages of high energy density and cycle service life. Nowadays, the lithium batteries equipped with electric vehicles on sale mainly include lithium iron phosphate batteries and ternary lithium batteries, and there are significant differences between these two batteries in their own characteristics, let's talk about lithium iron phosphate batteries first.

Lithium iron phosphate batteries

At present, there are few models using lithium iron phosphate batteries, and the more typical one is the electric vehicle DENZA jointly established by BYD and Daimler Group. Its thermal stability is the best in the current automotive lithium battery, only at the high temperature of 500-600 °C, its internal chemical composition begins to decompose, and because the number of lithium iron phosphate is less than that of lithium batteries, such as DENZA uses 144 lithium iron phosphate batteries, compared with lithium batteries, the number of batteries is much less, and the burden on its BMS battery management system is smaller. However, due to the battery energy density of lithium iron phosphate batteries of 100-110Wh/kg, compared with ternary lithium batteries, its battery energy density is poorer, resulting in the same weight of the battery, the mileage is much worse than that of ternary lithium batteries, so most car companies on the market do not use it.