Analysis of the charge and discharge characteristics of lithium batteries

The charge and discharge characteristics of lithium batteries The positive electrode of the cell is LiCoO2, LiNiO2 and LiMn2O2. During this period, LiCoO2 was originally a crystal with a stable layer structure. However, when xLi ions are removed from LiCoO2, its structure may change, but whether it changes depends on the size of x. Through research, it is found that when x>0.5, the structure of b1-xcoo2 is extremely unstable, the crystal will collapse, and the external appearance is the collapse of the cell. Therefore, the battery should be used to control the value of x in b1-xcoo2 by binding the charging voltage. The charging voltage is generally not greater than 4.2v, so x is less than 0.5. At this time, the crystal shape of b1-xcoo2 is still stable. -C6 itself has its own characteristics, when the first time to positive LiCoO2-C6, when Li returns to the positive electrode to discharge LiCoO2, but becomes a necessary part of the Li in the center of the cathode C6 to ensure normal insertion of LiCoO2-C6 next time , Otherwise the battery is short, in order to ensure that there is a part of Li in the anode C6, it is usually ended by bundling the discharge threshold voltage: the safe maximum charge voltage is 4.2V and below, and the discharge threshold voltage is 2.5V and above. The recall effect is used through crystallization, and this reaction rarely occurs in lithium batteries. However, due to various reasons, lithium batteries will still lose capacity after multiple recharges. The first is the modification of the positive and negative data itself. From a molecular level, the positive and negative hole structures containing lithium ions will gradually sink and block. From a chemical point of view, it is the passivation of positive and negative data, showing side effects and other stable compounds. There is also physical evidence that the positive electrode data is gradually declining, and so on. After all, the amount of lithium ions that can move freely during the charging and discharging process of the battery is reduced. Overcharging and discharging cause permanent damage to the electrodes of lithium batteries. From the molecular level, it can be intuitively known that anode carbon emissions will cause excessive release of lithium ions and a recessed layered structure. Overcharging will put too much lithium. The ions are forcibly stuffed into the structure of the cathode carbon, and some lithium ions can no longer be released. Improper temperature can cause other chemical reactions, and compounds that we did not anticipate appear in lithium batteries. Therefore, many lithium batteries have maintenance temperature control gaps or electrolyte additives between the positive and negative electrodes. When the battery heats up to a certain temperature, the composite membrane hole is closed or the electrolyte is denatured, the internal resistance of the battery increases until the circuit is disconnected and the battery no longer heats up to ensure that the battery charging temperature is normal. 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: Tesla uses cobalt-free batteries, that is, lithium iron phosphate batteries?