Conductive carbon black furnace black super P Li

In the charge discharge cycle of lithium battery, when there is current passing through the positive and negative electrodes, there will be a net reaction, indicating that the electrode has lost its original equilibrium state, and the electrode potential will deviate from the equilibrium potential, resulting in the commonly known polarization. The polarization of lithium battery can be divided into ohmic polarization, electrochemical polarization and concentration polarization. Polarization voltage is an important parameter for electrochemical reaction in lithium-ion batteries. If the polarization voltage is unreasonable for a long time, the precipitation of lithium metal in the negative electrode will be accelerated, and in serious cases, it will pierce the diaphragm and lead to short circuit. According to the initial experimental data of lithium battery, the conductivity of living material alone is not enough to meet the requirements of electron migration rate.
The conductive agent of lithium-ion battery has two important uses in the whole lithium-ion battery: conducting electrons and absorbing electrolyte; therefore, the addition of conductive agent can improve the rate, circulation, reduce the internal resistance and increase the battery capacity of lithium-ion battery; the conductive agent can not be added more or less, more will not only affect the energy density, but also affect the positive electrode capacity.
The primary function of conductive agent is to improve the electronic conductivity. In order to ensure that the electrode has good charging and discharging performance, a certain amount of conductive agent is usually added to the electrode plate to collect the micro current between the active substances and between the active substances and the current collector, so as to reduce the contact resistance of the electrode, accelerate the movement rate of electrons, and effectively improve the lithium ion in the electric field Therefore, the charge discharge efficiency of the electrode can be improved. In addition, the conductive agent can also improve the processability of the electrode, promote the infiltration of electrolyte on the electrode, and effectively improve the migration rate of lithium ion in the electrode material, reduce the polarization, so as to improve the charge discharge efficiency of the electrode and the service life of the lithium battery.
At present, the conductive agent in lithium-ion batteries is mainly conventional conductive carbon black sp. the conductive carbon black is characterized by small particle size, chain or grape shape under scanning electron microscope. Single carbon black particle has a very large specific surface area, which is closely stacked, which is conducive to the close contact between particles, forming a conductive network in the electrode, which is conducive to the adsorption of electrolyte, and thus improving the ionic conductivity At the same time, the carbon black particles agglomerate to form a branched chain structure, which can form a chain conductive structure with the active material, which helps to improve the electronic conductivity of the material. In addition, it can also play the role of liquid absorption and retention in the battery.
However, due to the large specific surface area of conductive carbon black, the process problem is that it is difficult to disperse and has strong oil absorption. Therefore, it is necessary to improve the mixing process of live material and conductive agent to improve its dispersion, and control the carbon black content within a certain range (usually below 1.5%).

General Characteristics

Carbon black Super P Li SEM

Structure and conductive mechanism of conductive agent

SEM pictures of various common conductive agents