Analysis of the cause of the lithium battery capacity attenuation

Source: 2020 - 03 - 29 the archite hits: what was the reason for the lithium battery capacity attenuation? 1. The misuse of lithium battery when lithium battery charging share less than 120%, no significant loss of capacity. When the lithium battery charging share greater than 120%, lithium deposits occur in the beginning of the cathode, due to form a thick layer of SEI film, impedance increases, leading to loss of active lithium. If overcharge continue, will cause the heat loss of lithium-ion batteries. When lithium battery charging rate is too high, the differentiation rate of electrolyte will be faster, the thicker sediments formed in the anode graphite, containing lithium deposits. In addition, a large proportion can also lead to battery charging and discharging capacity loss, this is because the volume is negative in the process of charging and discharging will attack shortened and inflation, the greater the charge and discharge current, shorten the expansion, the more intense, the pressure, the greater the cathode particles are more likely to attack the volume of a rapidly changing break or from a fluid collection, loop attenuation speed up. 2. Temperature coefficient needs to be pointed out that the working environment and conditions of lithium-ion batteries for its capacity of damage. Temperature is one of the key factors affecting the service life of lithium-ion batteries. Too high or too low temperature activity can lead to the development of lithium ion content, destroy the electrode data structure, dissolving metal ions, lead to serious capacity attenuation. The working temperature of conventional lithium-ion batteries: - 20 ℃ ~ 60 ℃, but generally lower than 0 ℃ after the function of the lithium battery will decline, with the decrease of discharge also, so the lithium battery fully functional working temperature, the general is 0 ~ 40 ℃. Some of the special environmental requirements of the temperature of the lithium battery is different, some can even be several hundred degrees Celsius. When the low temperature, the electrolyte viscosity increase, ionic conduction speed slow down, speed of the electronic/remove mismatch, the battery polarization is serious, charge and discharge capacity fell sharply. In particular, under the condition of the low temperature charging, li + from the anode will not be embedded in the cathode carbon layer of crystal lattice, formation of lithium metal crystal negative extremes, led to the decrease of the battery capacity, charging low temperature for a long time can lead to lithium dendrites pierced diaphragm, cause a short-circuit. The main factors influencing the lithium battery capacity attenuation is the positive and negative data structure damage or inactivation, the differentiation of the electrolyte, the misuse of lithium-ion batteries, etc. Battery charging and discharging process is a confusion of the electrochemical process, and lead to battery capacity attenuation factor is not a single, the deterioration of one aspect can lead to other factors influence the battery capacity, cycle function, energy density, etc.