At present, lithium iron phosphate batteries are the most widely used batteries in electric vehicles and home energy storage system. They are safe and have a long lifespan, but lithium iron phosphate has a fatal disadvantage: its low temperature performance is slightly worse than other technical systems. Low temperature has a certain influence on the positive and negative electrolytes and binders of lithium iron phosphate batteries. For example, the positive electrode of lithium iron phosphate battery itself has poor conductivity. Under the influence of low temperature, the rate of graphite intercalation of lithium decreases, and the metal lithium on the negative surface is short-lived. Assuming the lack of time after charging is put into use, the lithium metal cannot be fully intercalated into the graphite, and a part of the metal lithium continues to exist on the surface of the negative, it may form lithium Dendrites affect the safety of the battery; at low temperatures, the viscosity of the electrolyte increases, and the resistance to lithium ion removal increases. In addition, in the production process of lithium iron phosphate batteries, the binder is also a very critical element, and low temperature will also have a greater impact on the function of the binder.

Influence of low temperature on lithium titanate battery

It is also a lithium ion battery, and the low temperature resistance of lithium titanate battery is better. The lithium potential embedded in the spinel structure of the lithium titanate cathode material is about 1.5v, which does not constitute lithium dendrites, and the volumetric strain during charging and discharging is less than 1%. The nano-lithium titanate battery can be charged and discharged at high current and fast charged at low temperature, which ensures the durability and safety of the battery. Lithium titanate batteries have the material advantage of low-temperature fast charging, which is difficult for other batteries to match. Why does charging take more temperature than discharging?

Many companies' battery products can be discharged normally at low temperature, but at the same temperature, it is difficult to charge normally, or even impossible to charge. When Li+ is embedded in a graphite material, the first thing to do is to dissolve it. This process consumes a certain amount of energy to prevent Li+ from dispersing into the graphite. In contrast, there is a solvation process for Li+ to enter the solution from the graphite material, and the solvation process does not consume energy, so Li+ can be quickly removed from the graphite. Therefore, the charge acceptability of graphite materials is significantly lower than the discharge acceptability.

At low temperatures, there is a certain risk of battery charging. Because the dynamic properties of graphite anodes change with decreasing temperature. During the charging process, the electrochemical polarization of the anode is significantly enhanced. The separated metallic lithium briefly forms lithium dendrites, which break through the separator and cause a short circuit between the positive and negative electrodes.

Prevents lithium-ion batteries from being charged at low temperatures. When the battery must be at a lower temperature, it is necessary to choose a small current (ie slow charging) to charge the lithium-ion battery, and the position after the lithium-ion battery is charged, and then ensure that the metal lithium anode reacts to separate the graphite, and the graphite anode begins to intercalate .

Industrial companies and scientific research institutions have carried out research and research on the low temperature resistance function of the battery, most of which focus on the improvement of the existing positive and negative electrode material technology, and through the positive environmental temperature of the battery part work under circumstances. With the further development of this technology, lithium ion batteries will have further breakthroughs in low temperature environments for electric vehicles and home energy storage system.