Introduction of Lithium Ion Battery and Lithium Ion Battery Pack

Lithium-ion battery is a kind of rechargeable battery, which mainly depends on the movement of lithium ions between the positive electrode and the negative electrode through the electrolyte to achieve charging and discharging. According to the different electrolyte materials used in lithium-ion batteries, lithium-ion batteries can be divided into two categories: liquid lithium-ion batteries and polymer lithium-ion batteries. The former uses liquid electrolytes, while the latter uses solid polymer electrolytes instead. There are two forms, dry and colloidal. In addition to the different electrolytes used in these two types of lithium-ion batteries, the positive and negative materials and working principles they use are basically the same. At present, lithium-ion batteries use lithium-containing compounds as the positive electrode and carbon materials as the negative electrode. There is no metal lithium in the positive and negative electrode materials, only lithium ions. The positive electrode materials include lithium sulphate, lithium manganate, ternary materials and lithium iron phosphate, and the negative electrode is generally graphite. As shown in Figure 1, a lithium-ion battery is mainly composed of a positive electrode, a negative electrode, an electrolyte, a separator, and a battery case. The diaphragm adopts porous insulating material, which is mainly used to isolate the positive and negative electrodes of the battery. It prevents electrons from moving between the positive and negative electrodes of the battery, but allows lithium ions (Li+) to move between the positive and negative electrodes through the micropores on the diaphragm. When a lithium ion battery is charged, Li+ is released from the gap of the positive electrode under the use of electric field force, and inserted into the negative electrode through the electrolyte through the separator. At this time, the negative electrode is in a rich state and the positive electrode is in a lithium-poor state; On the contrary, Li+ is extracted from the gap of the negative electrode and inserted into the positive electrode through the electrolyte. At this time, the positive electrode is in the lithium-rich state and the negative electrode is in the lithium-poor state. Therefore, during the charging and discharging cycle, Li+ undergoes intercalation and deintercalation reactions on the positive and negative electrodes respectively, Li+ moves back and forth between the positive and negative electrodes, and electrons move between the positive and negative electrodes of the battery through the battery's external lead to form a charge, Discharge current. Therefore, people vividly refer to lithium-ion batteries as rocking chair batteries. The operating voltage of a lithium ion battery depends on the lithium ion intercalation compound itself and the concentration of lithium ions constituting the electrode. Due to the small voltage and capacity of single lithium ion batteries, it cannot meet the requirements of the use of automobiles. It is necessary to combine n single lithium ion batteries to form a battery pack (commonly known as battery pack) before they can be used as power lithium batteries for automobiles. Usually, the automobile power lithium battery pack is assembled by dozens or even hundreds of single cells. In a battery pack, there are bound to be individual differences in the capacity and voltage of the single cells, which makes it difficult for each single cell to be consistent during charging and discharging. The over-discharge, over-charge or internal short circuit of the single battery will heat up the battery, which will not only affect the service life of the battery, but also have safety risks. Therefore, in order to ensure the safety and service life of the battery pack, the voltage, temperature and current collection lines are generally set in the lithium-ion battery pack, so that the battery management system (BMS) can collect the parameters of the battery pack and perform real-time monitoring. To ensure that the battery pack is in normal working condition. 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: Detailed explanation of the precautions for the use of electric vehicle batteries