A kind of diffusion connection method of composite electrode of lithium battery

Abstract

The invention relates to the technical field of lithium batteries, in particular to a diffusion connection method of a composite electrode of a lithium battery. The diffusion connection method comprises the following steps that (A), respectively mounting diffusion molds on a positive electrode and a negative electrode; (B), mounting an aluminum polar rod on the diffusion mold positioned on the positive electrode, and mounting a copper pole bottom plate on the diffusion mold positioned on the negative electrode; (C), applying pressure between the aluminum polar rod and the copper polar bottom plate under a vacuum environment, and realizing power-on between the positive electrode and the negative electrode and enabling the aluminum polar rod and the copper pole bottom plate to perform diffusion connection at a constant temperature; and (D), cooling the aluminum polar rod and the copper pole bottom plate. According to the diffusion connection method of the composite electrode of the lithium battery disclosed by the invention, through control over the temperature, the pressure, the current and the vacuum degree, the quick diffusion connection between the aluminum polar rod and the copper pole bottom plate for a pole-shaped lithium battery cover plate is realized; and moreover, the time is short, the loss is less, the pollution is avoided, and batch production is realized.

Description

technical field [0001] The invention relates to the technical field of lithium batteries, in particular to a method for diffusion connection of composite electrodes of lithium batteries. Background technique [0002] With the increase in the use of coal and oil, non-renewable energy is becoming more and more scarce. It is of great significance to switch to power sources to reduce the use of non-renewable energy, so the research on lithium-ion batteries is very important. At present, the power supply used in electric vehicles and electric tools generally needs to have the characteristics of high capacity and high power, and the discharge current of the battery will also reach hundreds of amperes, which puts forward higher requirements for the connection of the battery pack. At present, there are mainly two methods for connecting the batteries of the battery pack. One is that the battery pole and the connecting row are fastened by nuts; the second is that the connecting row a...

AI Technical Summary

Problems solved by technology

The first connection method will cause the nut to loosen due to vibration, oxidation, etc. after long-term use, which will inevitably lead to serious heating and high temperature at the connection, which will increase the internal resistance of the battery, and will even lead to battery failure; Due to the constraints of equipment, process and other factors, the second connection method cannot increase the size of the connection row, which leads to the requirement that high current discharge cannot be passed; the third connection method needs to use more raw materials for grinding and connection, and the loss of raw materials is large. There are many steps and processes, which are time-consuming and cannot be commercialized

[0003] The traditional pole-shaped lithium battery cover plate uses vacuum brazing for copper and aluminum poles. On the one hand, the oxide film on the surface of the aluminum substrate is difficult to remove, and the brazing filler metal does not wet the base metal well, and cannot wet the reinforcing phase ; On the other hand, the conventional solder does not contain a reinforcing phase so that the strength of the welded joint is not high, but if the reinforcing phase is added to the solder before welding, it is easy to cause the segregation and depletion of the reinforcing phase in the brazing seam

Some scholars also use ultrasonic-assisted brazing of aluminum matrix composites. There is a dispersed reinforcement phase in the brazing seam. However, an ultrasonic generator with a certain power is required to assist in removing the oxide film on the surface of aluminum matrix composites during the welding process. Therefore, this method is suitable for large-scale Welding of dimensional members has limitations

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