How adaptable is the battery to temperature

The charging temperature of lithium-ion batteries should generally be restricted to 0-60°C. Excessive temperature of the battery will damage the battery and may cause explosion. Although the temperature is too low, it will not cause safety problems, but it is difficult to charge the electric vehicle battery. Because there will be a part of the heat energy inside the battery during the charging process, the temperature of the battery should be detected during high-current charging, and the charging should be stopped when the set charging temperature is exceeded to ensure safety. The high temperature cycle function of the lithium manganate battery is relatively poor, but the low temperature function is relatively good. The high temperature function of the lithium iron phosphate battery is better, but the low temperature function is relatively poor. In actual testing or application, the capacity of lithium iron phosphate batteries is greatly affected by temperature. When the temperature is 2~3℃, the capacity may differ by 1%~2%. The higher the temperature, the greater the discharged capacity. Strictly control the ambient temperature at the time. Within a certain range, with the increase in temperature, the increase in the capacity of lithium-ion batteries is more obvious. For example, the discharge capacity of a nickel-hydrogen battery at 55°C is only more than 90% of the capacity at room temperature, while the discharge capacity of a lithium-ion battery at 55°C can usually exceed the capacity at room temperature. Figure 3-19 shows the different discharge capacities of lithium iron phosphate batteries at 18～48℃ (based on the discharge capacity at 20℃). Schematic diagram of the discharge capacity curve of lithium-ion batteries at different low temperatures (used here to indicate general changing trends). Compared with the room temperature of 20°C, the capacity attenuation at the low temperature of -20°C is more obvious, and the capacity loss is more at -30°C, and even less than half of the capacity at -40°C. Let's take a look at the factors that affect low temperature performance. By comparing the relationship between capacity and electrolyte conductivity (Figure 2), it can be seen that the lower the temperature, the lower the conductivity of the battery electrolyte. When the conductivity decreases, the ability of the solution to conduct active ions decreases. The resistance to the internal reaction of the battery will increase (this resistance is represented by impedance in electrochemistry), resulting in a decrease in discharge capacity, that is, a decrease in capacity. Furthermore, by measuring the impedance of each part (positive electrode, negative electrode, electrolyte) inside the battery, the influence of each part on the battery impedance can be seen (Figure 3). When the temperature is less than about -10℃, the interface impedance of the positive electrode and the negative electrode (graphite as an example in the figure) increases rapidly, and the impedance of the electrolyte rises rapidly after about -20℃. The combined result of these impedances is shown as The battery impedance rises rapidly around <-10°C (indicated by Li-ioncell in the figure). Saft, a famous French battery company, once studied the effect of high temperature on battery performance through 2Ah cylindrical batteries (positive electrode material NCM, using PVdF binder, negative electrode material carbon, using CMC/SBR binder), and compared the differences between the two batteries. High temperature conditions: B2 battery-first cycle at 60°C for 2 times, then cycle at 85°C B3 battery-first cycle at 60°C for 2 times, then cycle at 120°C. Statement: Some pictures and content of articles published on this site From the Internet, if there is any infringement, please contact to delete the previous article: How to prevent wrong charging of car batteries