Method for recycling negative electrode of lithium ion battery

Abstract

The invention relates to the technical field of batteries, in particular to a method for recycling a negative electrode of a lithium ion battery, which comprises the following steps of: firstly, removing metal ions in graphite by using a wet method; secondly, the recycled graphite is subjected to heat treatment in the air atmosphere, the conductive agent and the binder are removed, and finally the material is further coated with pyrolytic carbon. The method realizes effective recovery and regeneration of the graphite material in the waste lithium ion battery, and has important economic and social values.

Description

Technical Field

[0001] The invention relates to the technical field of batteries, and in particular to a method for recycling negative electrodes of lithium-ion batteries. Background Art

[0002] With the increasing use of electric vehicles around the world, the consumption of lithium-ion power batteries has increased dramatically, so a large number of lithium-ion power batteries are retired from electric vehicles every year. Echelon use as storage batteries will be the preferred choice for these retired batteries. However, for those scrapped batteries that cannot be used in echelons, disassembly and recycling of valuable materials is the only option.

[0003] Recovering high-value metal elements (such as Li, Ni, Co, Al and Cu) from scrapped lithium-ion batteries is the main focus of current recycling processes. However, since the added value of anode materials is lower than that of the above-mentioned precious metal materials and the regeneration process is difficult, the recycling and reuse of anode materials has not attracted widespread attention so far. Considering the rapid increase in the number of scrapped lithium-ion batteries, it is believed that the fully closed cycle reuse of recovered negative electrode materials after effective regeneration can also bring considerable economic benefits and achieve sustainable development of the lithium-ion power battery industry. The traditional mechanical separation method of separating negative electrode active materials and current collectors is not only difficult to process on a large scale, but also a large amount of impurities will stick to the separated products, which increases the difficulty of impurity removal; wet processing can be processed in large quantities, and the separation efficiency is high, and the impurities in the separated products are less. In addition, the use of pyrolysis to remove impurities can volatilize the electrolyte and decompose the binder.

[0004] Therefore, the comprehensive use of various separation and recovery methods to treat waste graphite negative electrodes can effectively recover all components of the negative electrode. Summary of the invention

[0005] This scheme provides a method for recycling negative electrodes of lithium-ion batteries, which realizes the effective recycling of graphite materials in waste lithium-ion batteries and has important economic and social value. It specifically includes the following steps:

[0006] Step 1: After the recovered negative electrode graphite material is acid-leached in H2SO4 solution for 3 hours, it is filtered, washed and dried to remove metal ions in the graphite material;

[0007] Step 2: The dried graphite material is transported to a rotary kiln through a pipeline, heated to decompose the adhesive in the graphite material, rinsed with water after heat treatment, and dried again to remove the residual conductive agent and adhesive in the graphite material;

[0008] Step 3: The graphite material after heat treatment in step 2 needs to be re-coated.

[0009] Preferred technical solution 1: The coating process in step 3 is as follows: first, the treated graphite material is dispersed in a phenolic resin-ethanol solution, reacted in a reactor for 5 hours, filtered, and transported to a drying furnace for curing, the cured graphite material is transported to a rotary kiln for calcining with nitrogen, and finally the graphite material is sent to a crusher for crushing.

[0010] Preferred technical solution 2: In step 2, the heating temperature of the rotary kiln is set to 500° C., and the heating time is set to 1 hour.

[0011] Preferred technical solution three: the mass ratio between the phenolic resin and ethanol is phenolic resin:ethanol=6:100.

[0012] Preferred technical solution 4: The concentration of the H2SO4 solution in step 1 is 3%.

[0013] Preferred technical solution five: the acid leaching temperature in step one is 80°C.

[0014] Preferred technical solution six: the curing temperature in the drying oven is 120° C. and the curing time is 1 hour.

[0015] Preferred technical solution seven: the calcination temperature is 900° C. and the calcination time is 1 hour.

[0016] The above structure enables this solution to have the following beneficial effects:

[0017] The metal ions in the graphite are removed by wet method, and the recovered graphite is heat treated in an air atmosphere to remove the conductive agent and binder. The material is further coated with pyrolytic carbon, which achieves the effective recycling and regeneration of graphite materials in waste lithium-ion batteries, which has important economic and social value. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0019] Figure 1 This is the principle diagram of graphite recycling and regeneration in this scheme;

[0020] Figure 2 This is the graphite recycling process diagram for this scheme. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0022] See also Figure 1-Figure 2 , a method for recycling negative electrodes of lithium-ion batteries, comprising the following steps:

[0023] Step 1: After the recovered negative electrode graphite material is acid-leached in a 3% H2SO4 solution at 80°C for 3 hours, it is filtered, washed and dried to remove metal ions in the graphite material;

[0024] Step 2: After the graphite material in step 1 is dried, it is transported to a rotary kiln through a pipeline, and the temperature is set to 500° C. and the heating time is set to 1 hour in an air atmosphere to decompose the adhesive in the graphite material. After the heat treatment, it is rinsed with water and dried again to remove the residual conductive agent and adhesive in the graphite material;

[0025] Step 3: The graphite material after heat treatment in step 2 needs to be re-coated, and the coating process is as follows: First, the treated graphite material is dispersed in a phenolic resin-ethanol solution (the mass ratio between phenolic resin and ethanol is phenolic resin: ethanol = 6:100), reacted in a reactor for 5 hours, filtered, transported to a drying furnace and cured at 120°C for 1 hour, the cured graphite material is transported to a rotary kiln and burned at 900°C for 1 hour with nitrogen, and finally the graphite material is sent to a crusher for fine crushing.

[0026] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for recycling negative electrodes of lithium-ion batteries, It is characterized in that The steps include: Step 1: After the recovered negative electrode graphite material is acid-leached in H2SO4 solution for 3 hours, it is filtered, washed and dried to remove metal ions in the graphite material; Step 2: The dried graphite material is transported to a rotary kiln through a pipeline, heated to decompose the adhesive in the graphite material, rinsed with water after heat treatment, and dried again to remove the residual conductive agent and adhesive in the graphite material; Step 3: The graphite material after heat treatment in step 2 needs to be re-coated.

2. A method for recycling negative electrodes of lithium-ion batteries according to claim 1, It is characterized in that The coating application process in step 3 is as follows: First, the treated graphite material is dispersed in a phenolic resin-ethanol solution, reacted in a reactor for 5 hours, filtered, and transported to a drying furnace for solidification. The solidified graphite material is transported to a rotary kiln for calcination with nitrogen, and finally the graphite material is sent to a crusher for crushing.

3. A method for recycling negative electrodes of lithium-ion batteries according to claim 1, It is characterized in that In step 2, the heating temperature of the rotary kiln is set to 500° C., and the heating time is set to 1 hour.

4. A method for recycling negative electrodes of lithium-ion batteries according to claim 2, It is characterized in that The mass ratio between the phenolic resin and ethanol is phenolic resin:ethanol=6:

100.

5. A method for recycling negative electrodes of lithium-ion batteries according to claim 1, It is characterized in that The concentration of the H2SO4 solution in step 1 is 3%.

6. A method for recycling negative electrodes of lithium-ion batteries according to claim 5, It is characterized in that The acid leaching temperature in step 1 is 80°C.

7. A method for recycling negative electrodes of lithium-ion batteries according to claim 2, It is characterized in that The curing temperature in the drying oven is 120° C. and the curing time is 1 hour.

8. A method for recycling negative electrodes of lithium-ion batteries according to claim 2, Features: The calcination temperature is 900° C. and the calcination time is 1 hour.

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