Low-temperature performance of lithium batteries and analysis of factors restricting low-temperature performance of lithium batteries

Among all the environmental factors, temperature has the greatest impact on the charge and discharge performance of the battery, and the electrochemical reaction of the lithium battery at the electrode/electrolyte interface is related to the ambient temperature. At low temperatures, the viscosity of the electrolyte decreases and the conductivity decreases, and the activity of the active material will also decrease, which will increase the concentration difference of the electrolyte, strengthen the polarization, and terminate the charging earlier. More importantly, the diffusion rate of lithium ions in the carbon anode will be slower, and the temperature will drop, and the reaction rate of the electrode will also drop. Lithium batteries work under low temperature conditions. The capacity of the battery drops sharply and the polarization is strengthened. Under low temperature conditions, lithium ions are difficult to be inserted into the negative electrode and relatively easy to be extracted from the negative electrode, which leads to a decrease in capacity and a polarization of the battery. The change is related to the decrease in the conductivity of the electrolyte at low temperatures, the decrease in the diffusion rate of lithium ions in the electrode, and the increase in impedance due to the formation of a new SEI film on the surface of the negative electrode due to the deposition of lithium metal during the charging process. It is necessary to preheat the battery before charging or using the lithium battery in a low temperature environment. The way that the battery management system in the electric vehicle heats the battery can be roughly divided into two categories: external heating and internal heating. These heating methods are generally located in the battery pack, or set in the container of the thermal circulation medium. The internal heating method heats the battery by exciting the electrochemical substances inside the battery through alternating current, so that the battery itself generates heat. Factors that restrict the low-temperature performance of lithium batteries 1. The three-dimensional structure of the cathode material restricts the diffusion rate of lithium ions. Different cathode materials have different three-dimensional structures, and the effect is particularly clear at low temperatures; 2. The phase between the electrolyte and the anode and the diaphragm at low temperatures The capacitance becomes worse; the viscosity of the electrolyte increases, and even partially solidifies, resulting in low ion conductivity; 3. The diffusion coefficient of lithium ions in the active material decreases at low temperature, and the charge transfer resistance increases significantly; 4. The negative electrode of lithium battery in low temperature environment The SEI film is thickened, and the impedance of the SEI film increases, which leads to a decrease in the conduction rate of lithium ions in the SEI film; 5. At low temperatures, the negative electrode lithium is severely precipitated, and the precipitated metal lithium reacts with the electrolyte, and its product deposition leads to the thickness of the solid electrolyte interface Added. Disclaimer: Some pictures and content of the articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous article: What is the reason why there are more solar lithium batteries than lead-acid batteries?