Why does the capacity of lithium-ion batteries become lower at low temperatures?

When used in a low-temperature environment, lithium-ion batteries have problems such as low capacity, serious attenuation, poor cycle rate performance, obvious lithium ion evolution, and unbalanced lithium ion deintercalation, which make them unable to meet the use of certain specific areas. In a low temperature environment, the viscosity of the electrolyte increases, and even partially solidifies, resulting in a decrease in the conductivity of the lithium-ion battery. The compatibility between the electrolyte, the negative electrode and the separator becomes poor in a low temperature environment. Lithium ions are severely precipitated in the negative electrode of a lithium-ion battery in a low temperature environment, and the precipitated metal lithium ions react with the electrolyte, and the product deposition causes the thickness of the solid electrolyte interface (SEI) to increase. In the low temperature environment, the diffusion system of the lithium ion battery in the active material decreases, and the charge transfer resistance (Rct) increases significantly. According to effective statistics, when a lithium-ion battery is discharged at minus 20°C, only about 30% of the nominal capacity. Some traditional low-temperature lithium-ion batteries can meet the normal discharge between -20~+55℃. However, in aerospace, polar scientific research, special equipment and other fields, lithium-ion batteries are required to work normally at -40°C. Therefore, the emergence of low-temperature lithium-ion batteries is of great significance. Low-temperature lithium-ion battery is a special type of lithium-ion battery specially developed for the low-temperature defects inherent in the performance of chemical power sources. The low-temperature lithium-ion battery uses VGCF and activated carbon with a specific surface area of u200bu200b(2000±500)㎡/g as additives and its matching positive and negative electrode materials. Special electrolyte with special additives is injected to ensure the low-temperature discharge of the low-temperature lithium-ion battery. At the same time, the volume change rate of 24h at 70℃ is ≦0.5%, and it has the safety and storage functions of conventional lithium-ion batteries. Low-temperature lithium-ion battery refers to the working temperature below -40℃, and can meet the national standard of lithium-ion battery GB31241-2014 'Safety requirements for lithium ion batteries and battery packs for portable electronic products' or the national military standard of the People's Republic of China GJB4477-2002 'Lithium battery Lithium-ion batteries required by 'Package General Specification'. Important application fields: special equipment, aerospace, polar scientific research, frigid rescue, power communication, public safety, medical electronics, railways, ships, robots and other fields. Low-temperature lithium-ion batteries have the advantages of light weight, high specific energy and longevity, and are widely used in various electronic devices. Among them, the low-temperature battery polymer lithium-ion battery also has the advantages of simple packaging, easy to change the geometric shape of the battery, ultra-light and ultra-thin and high safety, and has become the power source for many mobile electronic products. Ordinary civilian batteries cannot be used at -20°C, while low-temperature lithium-ion batteries can still be used at -50°C. At present, low-temperature batteries are generally used in a temperature environment of 0°C or below. In addition to communication power supplies, military mobile power supplies, signal power supplies, and small power equipment drive power supplies also use low-temperature batteries. These power supplies also have low-temperature performance requirements when working in the field. 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: What are the key factors in the performance of lithium-ion batteries