As we all know, low-temperature environments will have a certain impact on the performance of electric vehicle batteries. Low-temperature lithium batteries are special batteries specially developed for the low-temperature defects inherent in the performance of chemical power sources. From the perspective of low temperature, they can be divided into three types: civilian low-temperature batteries, special low-temperature batteries, and extreme environment low-temperature batteries.
Characteristics of low-temperature lithium batteries:
Special low-temperature lithium batteries are a requirement for temperature, mainly for low-temperature environments of minus 40°C, requiring the battery to be able to reach more than 80% of the rated capacity at 0.2C discharge. The main feature is that the capacity must be sufficient at low temperatures and can work normally.
At present, the commercial civilian low-temperature lithium batteries on the market have better performance in the form of lithium cobalt oxide formula lithium batteries in low-temperature polymer lithium batteries. After years of research and development, many lithium battery manufacturers have their own proprietary battery formulas, which have the following advantages in low-temperature lithium battery performance:
(1) High low-temperature discharge performance, with a minimum discharge efficiency of more than 60% at 0.2C at -50℃; at -40℃, the discharge capacity reaches 80% at 0.2C;
(2) Low-temperature lithium batteries have a wide operating temperature range, from -50°C to 50°C;
(3) Excellent low-temperature cycle performance, with a charge and discharge rate of 0.5C at -30℃, and a capacity of more than 85% after 300 cycles;
(4) High safety performance, UL/CE/UN certified;
(5) Flexible size, can be customized in size and shape according to customer needs;
(6) Compared with traditional lithium polymer batteries, it breaks through the discharge temperature limit of -20℃~60℃.
(7) It has the ability to be mass-produced and has good battery consistency;
(8) Low-temperature lithium batteries can generate large currents and maintain large capacity at -50°C;
(9) Low-temperature lithium batteries can still maintain their excellent performance under a -50°C working environment;
(10) Low-temperature lithium batteries can be widely used in cold climates and military equipment.
What are the effects of low temperature on the performance of lithium batteries?
At low temperatures, the viscosity of the electrolyte decreases. The conductivity decreases, and the activity of the active material also decreases. This will increase the concentration difference of the electrolyte, enhance polarization, and terminate the charging of the lithium battery early. Lithium iron phosphate has a fatal disadvantage. The low-temperature performance of lithium iron phosphate batteries is slightly worse than that of batteries of other technical systems. Low temperature has an impact on the positive and negative electrodes, electrolytes, and adhesives of lithium iron phosphate.
At low temperatures, the activity of the positive electrode material decreases, resulting in a decrease in the number of lithium ions that can move and bring discharge current, which is the fundamental reason for the decrease in capacity.
The performance of lithium batteries deteriorates severely at low temperatures, and some side reactions will occur during the charging and discharging process of lithium-ion batteries. The main side reactions are the irreversible reactions between lithium ions and electrolytes, which will cause the capacity of lithium batteries to decline and further deteriorate the battery performance.
Summary: Using lithium batteries at low temperatures will not perform well regardless of charging or discharging, and may affect the life span, so it should be avoided.
