The addition of conductive agents is still essential in the preparation process of lithium iron phosphate battery slurry. Adding conductive agents can form a conductive network in LiFePO, collect micro currents, reduce electrode contact resistance, accelerate electron migration rate, and thus improve the charging and discharging performance of LiFePO.
Lithium iron phosphate material has become a highly promising positive electrode material for lithium-ion batteries due to its low cost, good environmental compatibility, high specific capacity, and good stability. Due to the low conductivity of lithium iron phosphate materials, a certain amount of conductive agent needs to be added during ingredient preparation. The conductive agent has a large specific surface area and more particles per unit mass, which is conducive to forming a chain like conductive network in the electrode, thereby improving the conductivity of the electrode, helping to maximize the capacity of lithium iron phosphate batteries and reduce the polarization resistance of the battery.
Common conductive agents include carbon black, graphite, carbon fiber, metal fiber, etc. High structured carbon black has fine particles, tightly packed network chains, and a large specific surface area, which is conducive to the formation of a chain like conductive structure in the electrode. Among many types of carbon black, acetylene black (AB) is the best. It is generally believed that acetylene black has a low degree of lattice formation, and the Gibbs free energy of lithium ion insertion and extraction in it is not significantly different; Also, due to the high conductivity of acetylene black and its low resistance and heat release, its impact on the safety of lithium iron phosphate batteries is relatively small.
Graphite and carbon fiber have good conductivity, low density, stable structure, and chemical stability, and are also commonly used as conductive agents for lithium-ion battery cathode materials. Carbon nanotubes, as a type of nanofiber material, have a high aspect ratio, a large specific surface area, and good conductivity and thermal conductivity, making them theoretically an ideal conductive agent for lithium-ion batteries.
The content of conductive agents also has a significant impact on improving the charging and discharging performance of LiFePO4 lithium iron phosphate batteries. If the content of conductive agent is too low, it is difficult to form an effective conductive network, which cannot form sufficient electronic conductive channels and is not conducive to high current charging and discharging; If the content is too high, it reduces the relative content of active substances, resulting in a decrease in the volume specific capacity of the battery.
