Introduction to the structure of lead-acid batteries and lithium batteries

1. The structure of the lead-acid battery The positive electrode material of the lead-acid battery (VRLA) is mainly composed of PbO2, the negative electrode material is mainly composed of Pb, and the electrolyte is usually dilute sulfuric acid. In the discharge state of a lead-acid battery, the most important component of the positive electrode is lead dioxide, and the most important component of the negative electrode is lead; in the charged state, following the double sulfate reaction rule, the important components of the positive and negative electrodes have lead sulfate (PbSO4) crystal grains. The nominal voltage of a single-cell lead-acid battery is 2.0V, which can discharge to 1.5V and charge to 2.4V. In application, 6 single-cell lead-acid batteries are often connected in series to form a nominal 12V lead-acid battery. There are also 24V, 36V, 48V and so on. The theoretical specific energy is 166.9Wh/kg, and the actual specific energy is 35-45Wh/kg. Due to the conductivity of the electrolyte, high current charging is not allowed when lead-acid batteries are self-discharged and charged. Therefore, the charging of lead-acid batteries is generally limited to less than 0.3C. The processing technology of lead-acid batteries is relatively mature. Although many companies have made many innovations and breakthroughs in the preparation of positive and negative materials in this technology, there are no fundamental innovations and breakthroughs in the basic technology of using materials. On the basis of the improvement and innovation of the preparation process, the storage capacity, self-discharge and charging resistance of lead-acid batteries have been improved to a certain extent. But no qualitative change has taken place. The materials used in lead-acid batteries have a certain risk of environmental pollution. In the complex working environment of low-speed electric vehicles, electrolyte leakage is extremely likely, or other circumstances may cause the positive and negative materials in the lead-acid battery to escape to the environment, causing certain pollution to the environment. At present, the preparation of lead-acid batteries is relatively complete from the upstream lead mines and various processing plants, and the competition is relatively sufficient. In addition, the technology maturity of the industry development, including the localization rate of industrial equipment, is relatively complete. High, so the product price is relatively low, and it is very cost-effective to use on low-speed electric vehicles. 2. The structure of the lithium battery, the lithium battery is important to rely on the movement of lithium ions between the positive electrode and the negative electrode to work. During the charging and discharging process, Li+ intercalates and deintercalates back and forth between the two electrodes. The important thing for the positive electrode material is that the active material of lithium is generally lithium manganese oxide or lithium cobalt oxide, lithium nickel cobalt manganese oxide material (commonly known as ternary), lithium iron phosphate and other active lithium materials. The negative electrode material is important because the negative electrode uses lithium-carbon intercalation compound LiXC6, which is basically a carbon material with good performance and chemical stability, such as graphite, carbon fiber, glassy carbon, etc. In terms of negative electrode material, graphene is due to its excellent charge and discharge performance. More and more attention has been paid by various lithium battery manufacturers and investment institutions. The electrolyte is usually a carbonate solvent in which lithium hexafluorophosphate is dissolved, while the polymer is gel-like electrolyte. The current energy density of relatively hot lithium batteries is about 100-150Wh/kg, which is obviously much higher than that of lead-acid batteries. . Since the electrolyte uses organic solvents, the conductivity is very weak. Makes the self-discharge of the lithium battery very small. High current charging is allowed during charging. Therefore, the general charging of lithium batteries can reach 1C. The processing technology of lithium batteries is currently very mature, but there is still a long way to go in the localization of core materials such as positive and negative electrodes and separators. With the continuous progress and development of the assembly process and a large amount of domestic capital flocking to the lithium battery industry chain. Continuous breakthroughs in key raw materials, coupled with a large number of newly started lithium battery manufacturers in the past two years will be built and put into production in the next two years, will inevitably lead to an oversupply of lithium batteries, and prices will inevitably fall. With the intensive investment of capital and the improvement of the upstream and downstream industrial chain, the price of lithium batteries will surely reach a level acceptable for low-speed electric vehicles. More importantly, the material structure of the lithium battery itself determines that it will not pose a huge risk of environmental pollution. Disclaimer: Some pictures and content of articles published on this site are from the Internet, if there is any infringement, please contact to delete. Previous: What are the characteristics of 18650 lithium batteries?