As the commercialization of lithium batteries becomes more and more widespread, the charging and discharging process of the battery of the lithium battery on the surface of the positive electrode material is that when the battery is discharged, the lithium ions in the holes enter the positive active material, and if the current is increased, the polarization increases. The discharge is difficult, so the conductivity between the electrons is poor, and the conductivity of the active material is not enough. In order to ensure good charge and discharge performance of the electrode, a certain amount of conductive agent is usually added during the production of the pole piece. The function of collecting microcurrents between the active materials and the current collector.
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As the commercialization of lithium batteries becomes more and more widespread, the charging and discharging process of the battery of the lithium battery on the surface of the positive electrode material is that when the battery is discharged, the lithium ions in the holes enter the positive active material, and if the current is increased, the polarization increases. The discharge is difficult, so the conductivity between the electrons is poor, and the conductivity of the active material is not enough. In order to ensure good charge and discharge performance of the electrode, a certain amount of conductive agent is usually added during the production of the pole piece. The function of collecting microcurrents between the active materials and the current collector.
Conductive agent review
As the conductive material of lithium ion battery, there are mainly conductive agents such as SUPER-P, KS-6, conductive graphite, carbon nanotubes, graphene, carbon fiber VGCF, etc. These conductive agents have their own advantages and disadvantages. Specifically:
Application of conductive agent
01: SP
At present, the domestic lithium ion battery conductive agent is still based on the conventional conductive agent SP. Carbon black has better ionic and electronic conductivity, and carbon black has a larger specific surface area, which is advantageous for the adsorption of electrolytes and increases the ionic conductivity. In addition, the carbon primary particles agglomerate to form a branched structure, which can form a chain-like conductive structure with the active material, and contribute to improving the electronic conductivity of the material.
02: Graphite conductive agent
Basically artificial graphite, artificial graphite as a conductive agent has a smaller particle size than the artificial graphite of the negative electrode material, which facilitates compaction of the pole piece particles and improves ion and electron conductivity.
03: CNT conductive agent
The proportion of applications in the field of high-end digital batteries is more than 50%, and the proportion of applications in the field of power batteries is relatively low. However, in recent years, as power batteries have gradually improved performance requirements such as energy density, rate performance, and cycle life, the proportion of CNT conductive agents used in this field is gradually increasing.
04: Ketchen Black
Ketchen Black only needs a very low addition amount to achieve high conductivity, so Ketchen Black has always been the best in conductive carbon black, and has long been a leader in the market. Compared with other conductive carbon blacks used in batteries, Ketchen Black has a unique branched form. The advantage of this form is that the conductive contacts have many conductive contacts, and the branches form more conductive paths, so that a very high conductivity can be achieved with a small amount of addition (other carbon blacks are mostly spherical or flake-like, Therefore, a high amount of addition is required to achieve the required electrical conductivity).
Keqin Black is currently the leading superconducting carbon black. At present, the top 10 of lithium battery are basically used or tested. Among them, EC-300J is mainly used for nickel-hydrogen and nickel-cadmium batteries; ECP and ECP-600JD are mainly used for lithium batteries with high rate, large capacity and current density, especially ECP-600JD. The industry generally believes that its superior conductivity, high purity and unique branched structure will emerge in the era of iron-lithium as a positive electrode material.
There are two types of products used in batteries for Ketchen Black: CarbonECP and CarbonECP600JD, CP300JD.
Conductive agent content
a) The role of the conductive agent in the electrode is to provide a channel for electron movement. The content of the conductive agent is suitable to obtain a higher discharge capacity and better cycle performance. When the content is too low, the number of electronic conductive channels is small, which is disadvantageous for large current charge and discharge; Too high reduces the relative amount of active material and reduces battery capacity.
b) The presence of the conductive agent can affect the distribution of the electrolyte in the battery system. Due to the space limitation of the lithium ion battery, the amount of electrolyte injected is limited, generally in a lean state, and the electrolyte is connected internally as a battery system. The distribution of the positive and negative ions has a crucial influence on the migration and diffusion of lithium ions in the liquid phase. When the content of the conductive agent in one end electrode is too high, the electrolyte is concentrated at this pole, and the lithium ion transport process of the other pole is slow, the polarization is high, and it is easy to fail after repeated cycles, thereby affecting the overall performance of the battery. .
C) When the content of the conductive agent reaches a turning point, too much will only reduce the electrode density and decrease the capacity, while too little will result in low utilization of the active material in the electrode and a decrease in high rate discharge performance.
Conductive agent outlook
According to the analysis, carbon nanotubes and graphene can be made into conductive paste at present, and the price is much more expensive than ordinary carbon black SP. Carbon black is a very mature conductive agent and the price is relatively stable. In the future, with the increase of the scale effect, the price of CNTs and graphene will be relatively large, and the future application prospects are objective.
Jiangsu Acrel Electrical Manufacturing Co., LTD. , https://www.acrel.com.pk