CN104600392A - Method for recovering electrolyte of waste lithium ion battery - Google Patents

Abstract

The invention discloses a method for recovering the electrolyte of a waste lithium ion battery, which comprises the following steps: 1) dissecting the waste lithium ion battery, taking out the battery cell, putting the battery cell into a centrifuge for separation, and obtaining the waste electrolyte; 2) ) Filter, decolorize, and dehydrate the obtained waste electrolyte; 3) Analyze the composition of the dehydrated waste electrolyte, supplement electrolyte and organic solvent to adjust the composition ratio of the electrolyte used in lithium-ion batteries, and make electrolyte products. The invention can realize the recycling of the electrolyte solution of the waste lithium battery, avoid the pollution of the environment by the electrolyte solution, and is highly efficient and environment-friendly. Recycled products can be used as electrolytes and returned to the lithium battery industry, saving resources and reducing pollution.

Description

A kind of waste lithium ion battery electrolyte recovery method

technical field

The invention relates to the field of recycling lithium ion batteries, in particular to a method for recycling the electrolyte of waste lithium ion batteries.

Background technique

Lithium-ion batteries are widely used in electronics, transportation, and other fields because of their significant advantages such as high voltage, large capacity, low cost, good safety performance, long life, no memory effect, and environmental friendliness. With the development of science and technology and the rapid development of the electric vehicle industry, people's demand for lithium-ion batteries has increased sharply, and the consumption of lithium-ion batteries is increasing. It is expected that in the next few years, a large number of waste batteries will be generated after the end of life of lithium-ion batteries. Lithium-ion electrolyte is an organic liquid, which will absorb water and deteriorate in the air. At the same time, it contains toxic components, which will pollute the environment if leaked in the air. In the green recycling technology of lithium-ion batteries, the electrolyte needs to be recycled or harmlessly treated. Therefore, in order to recycle and reuse materials, save costs and protect the environment, it is necessary to recycle lithium battery electrolyte.

At present, there are few researches at home and abroad on the recycling and collection of electrolyte in waste lithium-ion batteries. The Chinese invention patent application with the publication number CN201110427431 discloses a method for recovering the electrolyte of waste lithium-ion batteries. The organic solvent contained in the electrolyte is obtained mainly through high-vacuum decompression rectification and rectification, and is recovered after rectification and purification. Publication number CN201310290286 reports a method for recovering the electrolyte of waste lithium-ion batteries. The electrolyte is collected by high-speed centrifugation, and the organic solvent is recovered by extraction and rectification. Publication number CN201310374644 reports a method and device for collecting the electrolyte of waste lithium-ion batteries. The cut of the battery is tilted downward and placed in a vacuum negative pressure environment, and the battery is squeezed to collect the electrolyte. Publication number CN201410069599 reports a method for recycling the electrolyte of waste lithium-ion batteries, using low-temperature freezing to eliminate the hazards of the electrolyte, freezing the battery cells with liquid nitrogen, collecting ice-like particles of the electrolyte, and adding water through the distillation of the electrolyte As a catalyst for the decomposition of lithium hexafluorophosphate to achieve harmless treatment of the electrolyte. These methods have the disadvantages of low efficiency, high energy consumption, complicated process, high requirements on equipment, and disadvantages for industrialized production.

Contents of the invention

The purpose of the present invention is to provide a recycling method for the electrolyte of waste lithium-ion batteries. Aiming at the current situation of resource utilization of lithium-ion batteries, an environmentally friendly method is adopted to realize the recycling of the electrolyte of waste lithium-ion batteries and avoid the pollution of the electrolyte to the environment. , efficient and environmentally friendly. Due to the small amount of electrolyte and the difficulty in recycling, and when the electrolyte is infiltrated with the pole piece, it is even more difficult to separate. Therefore, this patent adopts centrifugal separation technology to process and recover the electrolyte. Through component analysis, electrolyte and organic solvent are added to make lithium The electrolyte commonly used in ion batteries is returned to the lithium battery industry, saving resources and reducing pollution.

The technical scheme of the present invention is: a kind of recovery method of waste lithium ion battery electrolyte, comprises the following steps:

1) Dissect the waste lithium-ion battery, take out the battery cell, put the battery cell into a centrifuge to separate, and obtain the waste electrolyte;

2) Filter, decolorize, and dehydrate the waste electrolyte obtained in step 1);

3) Analyze the composition of the waste electrolyte obtained in step 2), supplement the electrolyte and organic solvent to adjust the composition ratio of the electrolyte used in the lithium-ion battery, and make the electrolyte product.

Step 1) Operate under the condition of humidity < 30%, preferably under the condition of moisture content ≤ 1000ppm, and optimally operate under the condition of moisture content ≤ 20ppm, to prevent the electrolyte from absorbing water;

Preferably, step 1) optimally also includes: discharge the residual power of the used lithium battery, clean and remove impurities on the surface of the battery, and then dry it before dissecting it;

Preferably, step 1) optimally also includes: smashing the battery cells in step 1), centrifuging to obtain waste electrolyte, adding an organic solvent and repeating the countercurrent washing method several times, collecting the washing liquid; and collecting the collected The washing liquid is distilled and concentrated, and the solvent obtained by distillation is continued to be used as the washing liquid. After concentration, the washing liquid is mixed with the waste electrolyte for recovery;

Step 2) The filtration is: the waste electrolyte obtained in step 1) is left to settle or filtered to remove impurities such as positive plates, negative plates, and diaphragms;

The decolorization in step 2) is: add the waste electrolyte after filtering in step 2) to 1/10~1/5 weight ratio activated carbon for adsorption for 30min~5h;

The dehydration in step 2) is: adding molecular sieves with a weight ratio of 1/10 to 1/5 to the decolorized waste electrolyte in step 2), and dehydrating for 3 to 24 hours;

Step 3) The organic solvent includes: ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate, γ-butyrolactone, tetrahydrofuran, One or more mixtures of dimethyl ether, dimethoxymethane, and 1,2-dimethoxyethane;

Step 3) The electrolyte includes: one or more mixed electrolytes of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium difluorooxalate borate, and lithium perchlorate.

Compared with the prior art, the present invention has the advantages of:

1. The present invention realizes the simple treatment of the lithium-ion battery electrolyte without complicated chemical processes. The whole process is simple, efficient, easy to control and clean and environment-friendly.

2. The waste electrolyte recovered by this process is purified and returned to the lithium-ion battery industry after adjusting the ratio of electrolyte and organic solvent in the electrolyte.

The method for recovering the active components of the electrolyte from the waste lithium ion battery mentioned in the present invention can obtain the electrolyte through component analysis, replenish electrolyte and organic solvent, and can directly use it as the electrolyte of lithium ion battery, effectively realizing the electrolyte salt, organic Recycling of solvent resources. This method has simple process, less equipment investment, short production cycle, low recycling cost, high recycling efficiency, and no secondary pollution caused by the recycling process. It can play a positive role in reducing battery production costs, saving resources, and protecting the environment.

Detailed ways

The technical solutions provided by the present invention will be described in detail below in conjunction with specific examples. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, embodiments not described in this specification can be fully understood by those skilled in the art, and will not be described here. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also regarded as the protection scope of the present invention.

Example 1:

1) Discharge the collected waste lithium-ion batteries, discharge the residual power of the waste lithium batteries, and dissect the batteries under the condition of humidity <30%, put the battery cells into a centrifuge to separate them, and obtain the waste electrolyte;

2) Filter the waste electrolyte obtained in step 1), add activated carbon with a weight ratio of 1/5 for 30 minutes to decolorize;

3) Add the waste electrolyte obtained in step 2) to molecular sieves with a weight ratio of 1/5, and dehydrate at room temperature for 3 hours;

5) Analyze the composition of the waste electrolyte obtained in step 3), supplement electrolyte and organic solvent, and make lithium-ion battery electrolyte. The composition of the electrolyte is EC:DMC=1:1 (weight ratio), and the concentration of LiPF ₆ is 1mol/L.

Example 2:

1) Collect waste lithium-ion batteries, discharge the residual power of the waste lithium-ion batteries, clean and remove impurities on the surface of the batteries, dry them under the condition of humidity <30%, then dissect them, smash the battery cells, and use centrifugation to obtain waste electrolyte , then add 10 g each of ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC) and ethyl methyl carbonate (EMC), and repeat the countercurrent washing method 3 times to collect the washing solution;

2) Concentrate the collected washing liquid by distillation, and continue to use the solvent obtained by distillation as washing liquid. After concentration, the washing liquid and the waste electrolyte are mixed and recovered to obtain a mixed waste electrolyte;

3) Filter the mixed waste electrolyte obtained in step 2), and add 1/10 weight ratio of activated carbon to adsorb for 5 hours for decolorization;

4) Add 1/10 weight ratio molecular sieve to the mixed waste electrolyte obtained after decolorization in step 3), and dehydrate at room temperature for 24 hours;

5) Analyze the composition of the waste electrolyte obtained after dehydration in step 4), supplement electrolyte and organic solvent, and make lithium-ion battery electrolyte. The composition of the electrolyte is EC:DMC:DEC:EMC=1:1:1:1 (weight ratio), and the concentration of LiPF ₆ is 1mol/L.

Example 3:

1) Collect waste lithium-ion batteries, discharge the residual power of the waste lithium-ion batteries, clean and remove impurities on the surface of the batteries, dry them under the condition of humidity <30%, then dissect them, smash the battery cells, and use centrifugation to obtain waste electrolyte , then add 15g each of ethylene carbonate (EC) and diethyl carbonate (DEC), repeat the countercurrent washing method 3 times, and collect the washing solution;

2) Concentrate the collected washing liquid by distillation, and continue to use the solvent obtained by distillation as washing liquid. After concentration, the washing liquid and the waste electrolyte are mixed and recovered to obtain a mixed waste electrolyte;

3) Filter the mixed waste electrolyte obtained in step 2), and add 1/8 weight ratio of activated carbon to adsorb for 3 hours for decolorization;

4) Add the mixed waste electrolyte obtained after decolorization in step 3) to molecular sieves with a weight ratio of 1/6, and dehydrate at room temperature for 18 hours;

5) Analyze the composition of the waste electrolyte obtained after dehydration in step 4), supplement electrolyte and organic solvent, and make lithium-ion battery electrolyte. The composition of the electrolyte is EC:DEC=1:1.2 (weight ratio); the concentration of LiPF ₆ is 1mol/L, and the content of LiBF ₄ is 1%.

Example 4:

1) Collect waste lithium-ion batteries, discharge the residual power of waste lithium-ion batteries, clean and remove impurities on the surface of the batteries, dry them under the condition of moisture content ≤ 1000ppm, and then dissect them, smash the battery cells, and use centrifugation to obtain waste electrolysis Then add 15g each of ethylene carbonate (EC), diethyl carbonate (DEC) and 1,2-dimethoxyethane (DME), repeat the countercurrent washing method 3 times, and collect the washing solution;

2) Concentrate the collected washing liquid by distillation, and continue to use the solvent obtained by distillation as washing liquid. After concentration, the washing liquid and the waste electrolyte are mixed and recovered to obtain a mixed waste electrolyte;

3) Filter the mixed waste electrolyte obtained in step 2), and add 1/7 weight ratio of activated carbon to adsorb for 2 hours for decolorization;

4) Add the mixed waste electrolyte obtained after decolorization in step 3) to molecular sieves with a weight ratio of 1/6, and dehydrate at room temperature for 18 hours;

5) Analyze the composition of the waste electrolyte obtained after dehydration in step 4), supplement electrolyte and organic solvent, and make lithium-ion battery electrolyte. The composition of the electrolyte is EC:DEC:DME=1:1.2:1 (weight ratio); the concentration of LiPF ₆ is 1mol/L, and the content of LiBF ₄ is 1.5%.

Example 5:

1) Collect waste lithium-ion batteries, discharge the residual power of waste lithium-ion batteries, clean and remove impurities on the surface of the batteries, dry them under the condition of moisture content ≤ 1000ppm, and then dissect them, smash the battery cells, and use centrifugation to obtain waste electrolyte , then add 10g each of ethylene carbonate (EC), dimethyl ether (DME) and dimethoxymethane (DMM) and repeat the countercurrent washing method 3 times to collect the washing solution;

2) Concentrate the collected washing liquid by distillation, and continue to use the solvent obtained by distillation as washing liquid. After concentration, the washing liquid and the waste electrolyte are mixed and recovered to obtain a mixed waste electrolyte;

3) Filter the mixed waste electrolyte obtained in step 2), add activated carbon with a weight ratio of 1/5 for 30 minutes to decolorize;

4) Add the mixed waste electrolyte obtained after decolorization in step 3) to molecular sieves with a weight ratio of 1/7, and dehydrate at room temperature for 20 hours;

5) Analyze the composition of the waste electrolyte obtained after dehydration in step 4), supplement electrolyte and organic solvent, and make lithium-ion battery electrolyte. The composition of the electrolyte is EC:DME:DMM=1:1:0.8 (weight ratio); the concentration of LiPF ₆ is 1mol/L, and the content of LiClO ₄ is 2%.

Embodiment 6:

1) Collect waste lithium-ion batteries, discharge the residual power of waste lithium-ion batteries, clean and remove impurities on the surface of the batteries, dry them under the condition of moisture content ≤ 20ppm, and then dissect them, smash the battery cells, and use centrifugation to obtain waste electrolyte , then add 15 g each of dimethyl carbonate (DMC), diethyl carbonate (DEC) and ethylene carbonate (EC), repeat the countercurrent washing method 3 times, and collect the washing solution;

2) Concentrate the collected washing liquid by distillation, and continue to use the solvent obtained by distillation as washing liquid. After concentration, the washing liquid and the waste electrolyte are mixed and recovered to obtain a mixed waste electrolyte;

3) Filter the mixed waste electrolyte obtained in step 2), and add 1/9 weight ratio of activated carbon to adsorb for 3 hours for decolorization;

4) Add the mixed waste electrolyte obtained after decolorization in step 3) to molecular sieves with a weight ratio of 1/8, and dehydrate at room temperature for 18 hours;

5) Analyze the composition of the waste electrolyte obtained after dehydration in step 4), supplement electrolyte and organic solvent, and make lithium-ion battery electrolyte. The composition of the electrolyte is EC:DEC:DMC=1:1:1 (weight ratio); the concentration of LiPF ₆ is 1mol/L, and the content of LiODFB is 3%.

Embodiment 7:

1) Collect waste lithium-ion batteries, discharge the residual power of waste lithium-ion batteries, clean and remove impurities on the surface of the batteries, dry them under the condition of moisture content ≤ 20ppm, and then dissect them, smash the battery cells, and use centrifugation to obtain waste electrolyte , then add 15g each of ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC), repeat 3 times by countercurrent washing, and collect the washing liquid;

2) Concentrate the collected washing liquid by distillation, and continue to use the solvent obtained by distillation as washing liquid. After concentration, the washing liquid and the waste electrolyte are mixed and recovered to obtain a mixed waste electrolyte;

3) Filter the mixed waste electrolyte obtained in step 2), and add 1/8 weight ratio of activated carbon to adsorb for 3 hours for decolorization;

4) Add the mixed waste electrolyte solution obtained after decolorization in step 3) to molecular sieves with a weight ratio of 1/6, and dehydrate at room temperature for 12 hours;

5) Analyze the composition of the waste electrolyte obtained after dehydration in step 4), supplement electrolyte and organic solvent, and make lithium-ion battery electrolyte. The composition of the electrolyte is EC:DMC:EMC=1:1:1 (weight ratio), and the concentration of LiPF ₆ is 1mol/L.

Claims (9)

1. A method for recovering the electrolyte of a waste lithium-ion battery, characterized in that, comprising the steps: 1) Dissect the waste lithium-ion battery, take out the battery cell, put the battery cell into a centrifuge to separate, and obtain the waste electrolyte; 2) Filter, decolorize, and dehydrate the waste electrolyte obtained in step 1); 3) Analyze the composition of the waste electrolyte obtained after dehydration in step 2), supplement the electrolyte and organic solvent to adjust the composition ratio of the electrolyte used in the lithium-ion battery, and make the electrolyte product. 2. A method for recycling the electrolyte of waste lithium-ion batteries according to claim 1, characterized in that: said step 1) is operated under the condition of humidity <30%, more preferably under the condition of moisture content ≤ 1000ppm , Optimally operate under the condition of sub-content ≤ 20ppm to prevent the electrolyte from absorbing water. 3. A method for recovering the electrolyte of a waste lithium-ion battery according to claim 1, characterized in that: said step 1) optimally further comprises: discharging the residual power of the waste lithium-ion battery, cleaning and removing impurities on the surface of the battery, Dissected after drying. 4. A method for recycling waste lithium-ion battery electrolyte according to claim 1, characterized in that: said step 1) optimally further comprises: smashing the battery cells in step 1), and centrifuging to obtain waste Electrolyte, then add organic solvent and repeat multiple times by countercurrent washing, collect the washing liquid; distill and concentrate the collected washing liquid, continue to use the distilled solvent as washing liquid, and mix and recycle the concentrated washing liquid and waste electrolyte. 5. A method for recycling waste lithium-ion battery electrolyte according to claim 1, characterized in that: step 2) the filtering is: the waste electrolyte obtained in step 1) is left to settle or filtered to remove the positive plate , Negative plate, diaphragm and other impurities. 6. A method for recycling waste lithium-ion battery electrolyte according to claim 1, characterized in that: the decolorization in step 2) is: adding 1/10~1/5 weight of waste electrolyte after filtering in step 2) It can be adsorbed by activated carbon for 30min~5h. 7. A method for recovering the electrolyte of waste lithium-ion batteries according to claim 1, characterized in that: the dehydration in step 2) is: adding 1/10 to 1/5 of the weight of the waste electrolyte after decolorization in step 2) Ratio of molecular sieve, dehydration 3~24h. 8. A method for recovering the electrolyte of waste lithium-ion batteries according to claim 1 or 4, characterized in that: step 3) the organic solvent includes: ethylene carbonate, propylene carbonate, butylene carbonate, dicarbonate One of methyl ester, diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate, γ-butyrolactone, tetrahydrofuran, dimethyl ether, dimethoxymethane, 1,2-dimethoxyethane or a mixture of more than one. 9. A method for recovering the electrolyte of waste lithium-ion batteries according to claim 1, characterized in that: step 3) the electrolyte includes: lithium hexafluorophosphate, lithium tetrafluoroborate, lithium difluorooxalate borate, lithium perchlorate One or more mixed electrolytes.