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With the commercialization of lithium batteries more and more widely, lithium battery batteries in the cathode material surface charge and discharge process is when the battery discharge time, in the hole of lithium ions into the positive active material, if the current increases the polarization increase , The discharge is difficult, so that the electrical conductivity between the poor, just by the active substance of the province's conductivity is far from enough, in order to ensure good electrode charge and discharge performance, in the pole piece is usually added a certain amount of conductive agent , Between the active substances and the collector to collect the role of micro-current.
With the commercialization of lithium batteries more and more widely, lithium battery batteries in the cathode material surface charge and discharge process is when the battery discharge time, in the hole of lithium ions into the positive active material, if the current increases the polarization increase , The discharge is difficult, so that the electrical conductivity between the poor, just by the active substance of the province's conductivity is far from enough, in order to ensure good electrode charge and discharge performance, in the pole piece is usually added a certain amount of conductive agent , Between the active substances and the collector to collect the role of micro-current.
Summary of conductive agents
As the lithium ion battery conductive material used in the main conventional conductive agent SUPER-P, KS-6, conductive graphite, carbon nanotubes, graphene, carbon fiber VGCF, 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 or conventional conductive agent SP-based. Carbon black has better ionic and electrical conductivity, because carbon black has a greater specific surface area, it is conducive to the adsorption of electrolytes and improve ionic conductivity. In addition, the carbon particles are agglomerated to form a branched structure, which can form a chained conductive structure with the active material, which contributes to the improvement of the electrical conductivity of the material.
02: graphite conductive agent
The artificial graphite, which is a conductive agent, has a smaller particle size than that of the artificial graphite of the negative electrode material, which facilitates the compaction of the pole piece particles and improves the ionic and electrical conductivity.
03: CNT conductive agent
In the field of high-end digital battery applications more than 50% of the proportion of applications in the field of power battery is relatively low. However, in recent years, with the power battery on the energy density, magnification performance, cycle life and other performance requirements gradually increased, CNT conductive agent in the field of application is gradually increasing.
04: Keqin black
Keqin black only need a very low amount of added to achieve high conductivity, so Kelin black has been conductive carbon black in the best, a long time in the market in a leading position. Compared with other conductive carbon black used in batteries, Kochin black has a unique branched shape. The advantage of this form is that the conductive contact point of the conductor and more, the formation of more conductive branch channel, which only a small amount of added to achieve a very high conductivity (other carbon black mostly spherical or sheet, So the need to add a high amount to achieve the required electrical).
Keqin black is currently the forefront of the super conductive carbon black, the current top 10 lithium are basically in use or test. ECCP is mainly used for nickel-cadmium, nickel-cadmium batteries; ECP and ECP-600JD are mainly used for high-capacity large-capacity and current density of lithium, which is particularly prominent ECP-600JD. The industry generally believe that: its superior conductivity and high purity and unique branch structure, in the era of lithium iron for the cathode material will emerge.
There are two types of products used in batteries: CarbonECP and CarbonECP600JD, CP300JD.
The content of the conductive agent
A) the role of the conductive agent in the electrode is to provide electronic movement of the channel, the conductive agent content can be a higher discharge capacity and better performance, the content is too low, the electronic conduction channel is not conducive to high current charge and discharge; Too high to reduce the relative content of active substances, so that the battery capacity decreased.
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 the injected electrolyte is limited, and it is generally in the lean state, and the electrolyte is connected as an internal battery Positive and negative ions, the distribution of lithium ions in the liquid phase in the migration and diffusion has a crucial impact. When the content of the conductive agent in the one end of the electrode is too high, the electrolyte is enriched at this pole and the other lithium ion transfer process is slow, the degree of polarization is high, and it is easy to fail after repeated cycles, thus affecting the overall performance of the battery The
C) When the content of the conductive agent reaches a turning point on the line, too much will only reduce the electrode density, so that capacity decreased, and too little will lead to low efficiency of the active material in the electrode, and high rate discharge performance.
Conductive agent outlook
Analysis that the current carbon nanotubes and graphene can be made conductive paste, the price is much more expensive than ordinary carbon black SP. Carbon black is a very mature conductive agent, the price is relatively stable. CNT and graphene in the future with the large-scale effect of the increase, the price decline is relatively large space, the future application of objective.
