What effect does temperature have on lithium iron phosphate batteries?

The effect of temperature on the appearance of lithium iron phosphate batteries; the charging of lithium iron phosphate batteries is a process in which lithium ions are extracted from the positive electrode through the electrolyte migration and inserted into the negative electrode material. The lithium ions are polymerized to the negative electrode, and one lithium ion is captured by six carbon atoms. At low temperatures, the chemical reaction activity decreases, and the migration of lithium ions slows down. The lithium ions on the surface of the negative electrode have not been inserted into the negative electrode and have been reduced to metallic lithium, and precipitated on the surface of the negative electrode to form lithium dendrites, which are easy to pierce. The diaphragm causes a short circuit in the battery, which damages the battery and causes a safety accident. The discharge capacity of lithium iron phosphate battery at a temperature of 0～-20℃ is equivalent to 88.05%, 65.52% and 38.88% of the discharge capacity at a temperature of 25℃; the uniform discharge voltage is 3.134, 2.963V and 2.788V, -20℃ The uniform discharge voltage is 0.431V lower than that at 25°C. It can be seen from the above decomposition that as the temperature decreases, the uniform discharge voltage and discharge capacity of lithium batteries are reduced, especially when the temperature is -20°C, the discharge capacity and uniform discharge voltage of the battery drop faster. Low temperature has an impact on the positive and negative electrodes, electrolyte and binder of lithium iron phosphate batteries. For example, the positive electrode of a lithium iron phosphate battery has relatively poor electronic conductivity, and it is prone to polarization in low temperature environments, thereby reducing battery capacity; affected by low temperature, the speed of graphite lithium insertion is reduced, and metal lithium is likely to precipitate on the surface of the negative electrode. If it is left for a long time after charging If it is insufficient and put into use, the metal lithium cannot be fully embedded in the graphite again, and part of the metal lithium continues to exist on the surface of the negative electrode, which is very likely to form lithium dendrites, which affects the safety of the battery. At low temperatures, the viscosity of the electrolyte will increase, and the lithium ion migration resistance will also increase. In addition, in the processing technology of lithium iron phosphate batteries, the adhesive is also a very critical factor. Low temperature has an effect on the performance of the adhesive. There will also be a greater impact. Not only that, when the lithium iron phosphate battery is charged at low temperature, the lithium ions may not have time to be embedded in the graphite negative electrode, which precipitates to form metallic lithium dendrites on the surface of the negative electrode. This reaction consumes the lithium ions in the battery that can be repeatedly charged and discharged, and greatly When the battery capacity is reduced, the deposited metal lithium dendrites may also pierce the separator, thereby affecting the safety performance. The low-temperature characteristics of lithium iron phosphate batteries are determined by the characteristics of their materials and are difficult to change. Many experiments have been done, and the low-temperature performance of different materials of lithium batteries is also different. The hottest lithium iron phosphate at present is the worst in low-temperature performance. Our product discharges 89% of the maximum capacity at -10℃, which should be in the industry. It is relatively high; the discharge capacity can reach 95% at 55°C, and the attenuation at relatively low temperature is relatively small. 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: Analysis of the advantages and characteristics of industrial lithium batteries