What are the effects of conductive agents on the charge and discharge performance of lithium iron phosphate batteries?

The addition of conductive agent in the preparation process of lithium iron phosphate battery slurry is still essential. Adding a conductive agent can make it form a conductive network in LiFePO, collect micro current, reduce the contact resistance of the electrode, accelerate the migration rate of electrons, and thereby improve the charge and discharge performance of LiFePO. Lithium iron phosphate material has the advantages of low cost, good environmental compatibility, high specific capacity, and good stability, making it a potential cathode material for lithium batteries. Due to the low conductivity of lithium iron phosphate materials, a certain amount of conductive agent needs to be added when compounding. The specific surface area of u200bu200bthe conductive agent is large and there are many particles per unit mass, which is conducive to forming a chain conductive network in the electrode, thereby improving the conductivity of the electrode. , It helps to exert the capacity of lithium iron phosphate battery and reduce the internal polarization resistance of the battery. Commonly used conductive agents are carbon black, graphite, carbon fiber, metal fiber and so on. The high-structure carbon black has fine particles, tightly packed network chains and large specific surface area, which is conducive to the formation of a chain conductive structure in the electrode. Among the many types of carbon black, acetylene black (AB) is the best. It is generally believed that the degree of lattice formation of acetylene black is low, and the Gibbs free energy of lithium ion insertion and extraction is not much different; and because the conductivity of acetylene black is large, and the resistance exotherm is small, it affects iron phosphate The degree of safety of lithium batteries is small. Graphite and carbon fiber have the characteristics of good electrical conductivity, low density, stable structure and chemical stability, and are also often used as conductive agents for lithium battery cathode materials. As a kind of nanofiber material, carbon nanotube has a high aspect ratio, large specific surface area and good electrical and thermal conductivity. In theory, it is an ideal conductive agent for lithium batteries. The content of the conductive agent also has a distinct effect on improving the charge and discharge performance of LiFePO4 lithium iron phosphate batteries. If the content of the conductive agent is too low, it is difficult to form an effective conductive network, and can not form enough electronic conductive channels, which is not conducive to high current charging and discharging; if the content is too high, the relative content of the active material is reduced, and the volume specific capacity of the battery is reduced. The use of 1%CNT+3%superP+1%KS-6 composite additive in the positive electrode material of lithium iron phosphate battery can exert the synergistic use of the composite additive and can effectively improve the overall performance of the battery. The test data stated that the specific capacity of the cell reached 146.32mAh/g, which was higher than the specific capacity of the cell with the CNT+superP composite additive, which was 139.06mAh/g; the average value of the internal resistance of the former after the cell was divided was 1.0m. The latter is 3.25m. In addition, the self-discharge of the CNT+SP+KS-6 composite additive battery cell is small, and the battery cycle performance is excellent. After 2165 cycles of the battery, the capacity retention rate is 91.78%, and the battery cycle life is expected to be more than 4000 (80% DOD) , Which can meet the needs of power lithium-ion batteries and energy storage lithium iron phosphate batteries. 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.