Why does iron-lithium battery charge more temperature than discharge?

Many companies’ lithium battery products can achieve normal discharge at low temperatures, but at the same temperature, it is more difficult to achieve normal charging, or even unable to charge. When Li+ is embedded in the graphite material, it must first be desolvated. This process consumes a certain amount of energy. , Hindering the diffusion of Li+ into the graphite; on the contrary, when Li+ is released from the graphite material into the solution, there will be a solvation process, and solvation does not consume energy, and Li+ can quickly release the graphite. Therefore, the charge acceptance capability of graphite materials is clearly inferior to the discharge acceptance capability. In a low temperature environment, there are certain risks in the charging of iron-lithium batteries. Because as the temperature decreases, the kinetic characteristics of the graphite negative electrode become worse. During the charging process, the electrochemical polarization of the negative electrode is clearly intensified, and the precipitated metal lithium is likely to form lithium dendrites, piercing the diaphragm and causing the short circuit of the positive and negative electrodes. . Try to be wary of lithium batteries charging at low temperatures. When the battery has to be charged at low temperature, the lithium battery should be charged with a small current (ie slow charge) as much as possible, and the lithium battery should be fully stored after charging, so as to ensure that the metal lithium precipitated from the negative electrode can react with the graphite. Embedded in the graphite anode. The exploration and research of low-temperature resistance performance of iron-lithium batteries by companies and scientific research institutions in the industry mainly focus on the process improvement of existing positive and negative materials, and create conditions for the battery to work at low temperatures by increasing the local environmental temperature of the battery. Iron-lithium battery materials are moving towards nanometer, and the particle size, electrical resistance, and the axis length of the AB plane will affect the low temperature characteristics of the battery. From the perspective of the materials processed by the three processes, the granular graphite with a large interlayer spacing has relatively low bulk impedance and ion migration resistance; in terms of electrolyte, at present, energy storage electric low-temperature lithium iron phosphate batteries have been widely used in Inner Mongolia, the three northeastern provinces and other regions. Promotion. At present, many battery technicians use the principle of generating heat by energizing metal wires, adding nickel foil to the battery cell, and the nickel foil generates heat when energized, which increases the internal temperature of the battery. After reaching a certain temperature, the foil will automatically disconnect to ensure battery safety. It is known that in a test environment of -30°C, the battery using this technology can quickly heat up to above 0°C in 30 seconds, the discharge power is increased by more than 6 times, and the charging power is increased by more than 10 times. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete.