Low-efficiency and low-consumption water seal lithium ion battery film extraction process

Abstract

The invention discloses a low-efficiency and low-consumption water seal lithium ion battery film extraction process and belongs to the field of battery film wet-method preparation extraction. According to the process, a battery film is extracted in extraction equipment filled with an extraction agent; the extraction equipment comprises an extraction tank which is filled with the extraction agent and is sealed, a guide roller which is arranged inside the extraction tank and is used for conveying the film, and extraction agent heating devices; the film is submerged into the extraction agent; a water seal layer is further arranged on the upper layer of the extraction agent; a group of partition plates which are arranged high and low in a staggered manner are arranged inside the extraction tank; the partition plates inside the extraction tank form a snake-shaped extraction agent flowing channel; the heating devices are arranged on the partition plates; multi-stage counter flow extraction is implemented; the flowing direction of the extraction agent is opposite to the conveying direction of the film; the extraction agent is continuously conveyed into the extraction tank; the concentration of the extraction agent is greater than 99.5%; the liquid feeding amount is (2-5)*10<5>*(v<2>*W / L)m<3> / h; W represents the width of the film and has the unit of m; L represents the extraction length and has the unit of m; v represents the speed of the film and has the unit of m / h. By adopting the process, the extraction temperature of the extraction agent can be increased, and the extraction activity can be greatly improved.

Description

technical field [0001] The invention belongs to the field of wet preparation and extraction of battery thin films, and relates to a high-efficiency and low-consumption water-seal extraction process. The extraction process of the invention can increase the extraction temperature of methylene chloride to 20-35°C, greatly increasing the extraction activity of the extractant; and Due to the design of the water seal layer, the volatilization of the extraction agent is extremely small, which greatly reduces the volatilization consumption of the extraction agent, and achieves good economic benefits and production requirements. Background technique [0002] Lithium-ion battery thin film wet preparation process uses the principle of thermally induced phase separation, mixes polyethylene and small molecule agents in the same phase, forms a thick polyethylene sheet with micropores after quenching, and then stretches it to make a micron-sized film. Then, through the extraction process, ...

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Problems solved by technology

[0003] In the above-mentioned extraction process, the extractant used is dichloromethane with a density of 1.33g / cm 3 , with a boiling point of 39.8°C and is extremely volatile. The existing extraction process is the bottleneck that limits the production speed of lithium-ion battery films. The extraction effect is affected by extraction time, extraction concentration and extraction activity:

[0004] 1. The extraction time is related to the length of the diaphragm to be extracted, and the extraction time can only be increased by increasing the size of the extraction equipment;

[0005] 2. The extraction concentration, that is, the concentration of dichloromethane, can be increased by increasing the influent flow rate, the maximum concentration is 100%, and the improvement space is small, but it will cause a lot of waste of the extraction agent and environmental pollution, and the difficulty of post-processing of the extraction agent will increase;

[0006] 3. The extraction activity is related to the extraction temperature. The higher the temperature, the greater the activity and the better the extraction effect. However, in the existing diaphragm extraction, the extraction temperature that can be achieved is about 20°C

However, the shortcomings of the traditional extraction process are obvious: low extraction activity, large consumption of dichloromethane, and strong pungent odor

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