A method for recycling waste lithium-ion batteries using plasma ultrasound

Abstract

A method for recycling waste lithium-ion batteries by plasma ultrasound, firstly, the residual power of the waste lithium-ion batteries is emptied, then the shell is cut and removed under continuous vacuum conditions to obtain a battery core, and the electrolyte is extracted, and then the battery core is placed in a closed reaction box, and then an acid solution is transported into the box so that the acid solution submerges the battery core and a plasma instrument, and then an ultrasonic cavitation device is started to generate cavitation bubbles, and then the gaseous molecules in the cavitation bubbles are dissociated by a plasma instrument to generate highly active particles, and then the highly active particles collide with the active material in the battery core until there is no attachment on the current collector, and then the plasma instrument is turned off, and then the powder-liquid mixture is discharged from the bottom of the reaction box, and then filtered to obtain filter residue and filtrate, and the filtrate is a solution of metal ions in the active material. This design not only does not require the overall crushing of the battery, does not require the use of a large amount of acid and alkali reagents, but also has a high recycling efficiency and strong environmental protection.

Description

Technical Field

[0001] The invention relates to a method for recycling waste lithium-ion batteries, belongs to the cross-field of new energy, electrochemistry, physics and hydrometallurgy technology, and in particular to a method for recycling waste lithium-ion batteries by plasma ultrasound. Background Art

[0002] The main components of waste lithium-ion batteries are positive and negative electrode materials, electrolytes and flammable organic separators. Among them, the precious metals and organic chemicals in the positive and negative electrode materials will have a serious impact on environmental safety and human health. In addition, waste lithium-ion batteries contain more than 1 / 4 of lithium cobalt oxide / lithium nickel cobalt oxide / lithium iron phosphate, of which up to 20% of cobalt is an internationally recognized strategic material, and the mass fraction of copper and aluminum exceeds 10%. It also contains a large amount of recyclable plastic shells and metals. Therefore, it is very meaningful to recycle waste lithium-ion batteries.

[0003] Existing recycling technologies all require that the waste lithium-ion batteries be crushed as a whole, and then the crushed materials are distilled, and the electrolyte is recovered by condensation or directly removed by high-temperature incineration. After aluminum is removed by sodium hydroxide, inactivated materials containing nickel, cobalt, and manganese are obtained. This series of complicated steps requires the use of a large amount of acid and alkali reagents, and is accompanied by a series of problems such as the release of waste gas, discharge of waste liquid, and high energy consumption. In particular, the various metal chips generated by the overall crushing, such as iron shell chips, copper chips, and aluminum chips, not only increase the difficulty of recycling the corresponding metals, but also increase the interference with the subsequent recovery of inactivated materials.

[0004] The information disclosed in this background technology section is only intended to increase the understanding of the overall background of the application, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to ordinary technicians in the field. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects and problems existing in the prior art that batteries need to be crushed as a whole and a large amount of acid and alkali reagents need to be used, and to provide a method for recycling waste lithium-ion batteries by plasma ultrasound, which does not require the batteries to be crushed as a whole and does not require the use of a large amount of acid and alkali reagents.

[0006] To achieve the above objectives, the technical solution of the present invention is: a method for recycling waste lithium-ion batteries by plasma ultrasound, comprising the following processes performed in sequence:

[0007] Vacuum dehydration process: firstly, the residual power of the waste lithium-ion battery is emptied, and then the waste lithium-ion battery is placed in a closed battery cutting box, and then the vacuum pump is started to continuously vacuum the battery cutting box, and then the shell of the waste lithium-ion battery is cut and removed to obtain the battery core, and then, when the electrolyte is completely extracted by the vacuum pump, the vacuum operation is stopped, and then the shell and the battery core are taken out from the battery cutting box, and the battery core includes the current collector and the active material, binder and carbon black attached thereto;

[0008] Ultrasonic plasma process: first put the battery cell into a closed reaction box, which is equipped with an ultrasonic cavitation device and a plasma meter, and then transport an acid solution into the reaction box until the acid solution submerges the battery cell and the plasma meter, and then operate the acid solution with an ultrasonic cavitation device to generate cavitation bubbles, and then start the plasma meter to dissociate the gaseous molecules in the cavitation bubbles to generate highly active particles, and then the highly active particles collide with the active substances in the battery cell until there is no attachment on the current collector, and then turn off the plasma meter, and then discharge the powder-liquid mixture from the bottom of the reaction box. After the discharge, take out the current collector from the reaction box;

[0009] Post-recovery process: Filter the powder-liquid mixture to obtain filter residue and filtrate, wherein the filter residue is carbon black and the filtrate is a solution of metal ions in the active substance; the post-recovery operation of the filter residue includes making negative electrode materials, and the recovery operation of the filtrate includes electrodepositing metals.

[0010] After the metal ions in the filtrate in the post-recovery process are deposited, it is directly returned to the ultrasonic plasma process to be input into the reaction box and submerge the battery core together with the acid solution.

[0011] In the vacuum dehydration process, the residual power of the waste lithium-ion battery is emptied by soaking the waste lithium-ion battery in salt water to discharge the battery's own circuit, thereby emptying the residual power.

[0012] In the vacuum dehydration process, the operation of cutting the outer shell of the waste lithium-ion battery is completed by laser cutting.

[0013] In the vacuum dehydration process, the current collector includes a positive electrode current collector, a negative electrode current collector and a separator sandwiched therebetween.

[0014] In the ultrasonic plasma process, the acid solution is an organic acid or a mixture of an organic acid and an inorganic acid; and the pH value of the acid solution is 4-6.

[0015] In the ultrasonic plasma process, the components of the cavitation bubbles include water vapor and air; the highly active particles include hydrogen ions, peroxyl radicals and hydroxyl radicals.

[0016] In the ultrasonic plasma process, the active substance is any one of the following:

[0017] When the lithium-ion battery is a lithium iron phosphate battery, the active material is LiFePO 4 ;

[0018] When the lithium-ion battery is a lithium cobalt oxide battery, the active material is LiCoO 2 ;

[0019] When the lithium-ion battery is a ternary battery, the active material is LiNi x Co y Mn 1-x-y O 2 .

[0020] In the vacuum dehydration process, when the waste lithium-ion batteries are placed in a closed battery cutting box, there are at least two types of waste lithium-ion batteries and at least two types of corresponding active materials.

[0021] In the ultrasonic plasma process, the binder is decomposed into carbon dioxide and water by highly active particles, and the carbon dioxide is collected and used for the recovery and preparation of lithium carbonate.

[0022] In the ultrasonic plasma process, while the powder-liquid mixture is being discharged, the ultrasonic cavitator is continuously operated until the liquid surface of the powder-liquid mixture is flush with the ultrasonic cavitator, and then the ultrasonic cavitator is closed.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. In a method for recycling waste lithium-ion batteries by plasma ultrasound of the present invention, the overall concept is "plasma generates highly active particles to collide with the battery core, so that the metal ions in the active material are all stored in the acidic solution (i.e., the liquid in the powder-liquid mixture), thereby recovering the metal ions in the carbon black and the active material". In the specific operation, the waste lithium-ion battery is first cut to obtain the battery core, and the electrolyte is recovered at the same time, and then the highly active particles are generated to collide with the battery core, so that the metal ions in the active material are all stored in the acidic solution (i.e., the liquid in the powder-liquid mixture), thereby recovering the metal ions in the carbon black and the active material. The advantages of this design include: first, avoiding the overall destruction of the waste battery The invention can not only save a lot of acid, alkali reagents or organic extraction reagents consumed when separating various metal scraps, but also avoid the generation of more waste liquid and waste gas. Secondly, the metal materials destroyed in the prior art can be recycled as a whole, such as the shell and the current collector, which are convenient for reuse. The copper foil, aluminum foil and diaphragm can be recycled in large volumes. Thirdly, the shell and electrolyte are recycled in the vacuum dehydration process, and the active material, carbon black and current collector are recycled in the ultrasonic plasma process. It can be seen that all the materials that can be recycled in the waste lithium-ion battery are basically recycled by this design, and it has a high recycling efficiency. Therefore, the present invention not only does not need to crush the battery as a whole, does not need to use a large amount of acid and alkali reagents, but also has a high recycling efficiency and basically does not generate waste liquid and waste gas.

[0025] 2. In a plasma ultrasonic recycling method for waste lithium-ion batteries of the present invention, when recycling the active material attached to the current collector, the collision reaction between the highly active particles and the active material on the battery core is used, that is, hydrogen ions, peroxyl radicals, hydroxyl radicals and other highly active particles are first generated, and then the highly active particles themselves collide with the active material on the battery core electrode under the high energy and ultrasonic action, promoting the dissolution of composite oxides such as nickel, cobalt, manganese, and lithium in the active material, and can be peeled off from the current collector copper foil and aluminum foil at the same time, which is beneficial to the recycling of active materials and the recycling of metal materials in the current collector, and the recycling efficiency is high. At the same time, unlike the prior art, a large amount of acid and alkali reagents or extraction reagents are required, the cost is low, and it is easy to operate. In addition, it can avoid the generation and discharge of waste liquid and waste gas, and has strong environmental protection. Therefore, the present invention not only has high recycling efficiency and is easy to operate, but also has low cost and strong environmental protection.

[0026] 3. In a plasma ultrasonic recycling method for waste lithium-ion batteries of the present invention, the acid solution is limited to an organic acid or a mixture of an organic acid and an inorganic acid, and the pH value of the acid solution is 4-6. The advantages of this design when applied include: first, it can provide an acidic environment for the metal ions dissolved by the active substance after the collision reaction to avoid hydrolysis and precipitation; second, it can provide water vapor and air dissolved in the solution for the generation of highly active particles, so that the plasma instrument dissociates to generate highly active particles such as hydrogen ions, peroxyl radicals, and hydroxyl radicals; third, it will not damage metal substances such as the current collector, ensuring the subsequent smooth recycling; fourth, the amount used is very small, the cost will not be increased, and waste liquid and waste gas will not be generated. Therefore, the present invention not only has a high efficiency in decomposing active substances, the stability of the final product is strong, but also is easy to recycle the fluid collector, and the operating cost is low.

[0027] 4. In the plasma ultrasonic recycling method of waste lithium-ion batteries of the present invention, while the powder-liquid mixture is discharged, the ultrasonic cavitator is preferably continuously operated until the liquid surface of the powder-liquid mixture is flush with the ultrasonic cavitator, and then the ultrasonic cavitator is turned off. The advantages of this design include: after the powder-liquid mixture is obtained, the continuous operation of the ultrasonic cavitator can shake off the powder deposited and remaining on the surface of the current collector to avoid accumulation, accelerate its mixing into the powder-liquid mixture, and improve the recycling efficiency. Therefore, the recycling efficiency of the present invention is relatively high. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0030] See also Figure 1 , a method for recycling waste lithium-ion batteries by plasma ultrasound, comprising the following processes performed in sequence:

[0031] Vacuum dehydration process: firstly, the residual power of the waste lithium-ion battery is emptied, and then the waste lithium-ion battery is placed in a closed battery cutting box, and then the vacuum pump is started to continuously vacuum the battery cutting box, and then the shell of the waste lithium-ion battery is cut and removed to obtain the battery core, and then, when the electrolyte is completely extracted by the vacuum pump, the vacuum operation is stopped, and then the shell and the battery core are taken out from the battery cutting box, and the battery core includes the current collector and the active material, binder and carbon black attached thereto;

[0032] Ultrasonic plasma process: first put the battery cell into a closed reaction box, which is equipped with an ultrasonic cavitation device and a plasma meter, and then transport an acid solution into the reaction box until the acid solution submerges the battery cell and the plasma meter, and then operate the acid solution with an ultrasonic cavitation device to generate cavitation bubbles, and then start the plasma meter to dissociate the gaseous molecules in the cavitation bubbles to generate highly active particles, and then the highly active particles collide with the active substances in the battery cell until there is no attachment on the current collector, and then turn off the plasma meter, and then discharge the powder-liquid mixture from the bottom of the reaction box. After the discharge, take out the current collector from the reaction box;

[0033] Post-recovery process: Filter the powder-liquid mixture to obtain filter residue and filtrate, wherein the filter residue is carbon black and the filtrate is a solution of metal ions in the active substance; the post-recovery operation of the filter residue includes making negative electrode materials, and the recovery operation of the filtrate includes electrodepositing metals.

[0034] After the metal ions in the filtrate in the post-recovery process are deposited, it is directly returned to the ultrasonic plasma process to be input into the reaction box and submerge the battery core together with the acid solution.

[0035] In the vacuum dehydration process, the residual power of the waste lithium-ion battery is emptied by soaking the waste lithium-ion battery in salt water to discharge the battery's own circuit, thereby emptying the residual power.

[0036] In the vacuum dehydration process, the operation of cutting the outer shell of the waste lithium-ion battery is completed by laser cutting.

[0037] In the vacuum dehydration process, the current collector includes a positive electrode current collector, a negative electrode current collector and a separator sandwiched therebetween.

[0038] In the ultrasonic plasma process, the acid solution is an organic acid or a mixture of an organic acid and an inorganic acid; and the pH value of the acid solution is 4-6.

[0039] In the ultrasonic plasma process, the components of the cavitation bubbles include water vapor and air; the highly active particles include hydrogen ions, peroxyl radicals and hydroxyl radicals.

[0040] In the ultrasonic plasma process, the active substance is any one of the following:

[0041] When the lithium-ion battery is a lithium iron phosphate battery, the active material is LiFePO 4 ;

[0042] When the lithium-ion battery is a lithium cobalt oxide battery, the active material is LiCoO 2 ;

[0043] When the lithium-ion battery is a ternary battery, the active material is LiNix Co y Mn 1-x-y O 2 .

[0044] In the vacuum dehydration process, when the waste lithium-ion batteries are placed in a closed battery cutting box, there are at least two types of waste lithium-ion batteries and at least two types of corresponding active materials.

[0045] In the ultrasonic plasma process, the binder is decomposed into carbon dioxide and water by highly active particles, and the carbon dioxide is collected and used for the recovery and preparation of lithium carbonate.

[0046] In the ultrasonic plasma process, while the powder-liquid mixture is being discharged, the ultrasonic cavitator is continuously operated until the liquid surface of the powder-liquid mixture is flush with the ultrasonic cavitator, and then the ultrasonic cavitator is closed.

[0047] The principle of the present invention is described as follows:

[0048] In the present invention, an ultrasonic cavitation device is first used to operate the acid solution to generate cavitation bubbles, and then a plasma instrument is used to dissociate the gaseous molecules in the cavitation bubbles to generate highly active particles such as hydrogen ions, peroxyl radicals, and hydroxyl radicals. The reaction process is as follows:

[0049] O 2 +H 2 O→HO·+O:O·+H + ,

[0050] Then, the highly active particles react with the active materials on the battery cell pole piece under their own high energy and the action of ultrasound, promoting the dissolution of metals such as nickel, cobalt, manganese, and lithium in the active materials of the pole piece. The process is as follows:

[0051] LiCoO 2 (LiNi x Co y Mn 1-x-y O 2 Or LiFePO 4 )+HO·+O:O·+H + →Co 3+ +Ni 3+ +Mn 3+ +Li + +Fe 3+

[0052] , and can be peeled off from the current collector copper foil and aluminum foil. The acid solution provides the H required by the atomized plasma to promote the reaction of the active substances, but it does not cause dissolution effect on the current collector under the prepared acidity, and can well recycle consumables such as copper foil, aluminum foil and diaphragm.

[0053] In the ultrasonic plasma process of the present invention, the acid solution has two functions: one is to provide an overall acidic environment to ensure that the dissolved metal ions do not undergo hydrolysis and precipitation; the other is to be acted upon by the ultrasonic cavitator to generate cavitation bubbles, and then the plasma instrument dissociates the gaseous molecules in the cavitation bubbles to generate highly active particles. The basis for the generation of cavitation bubbles includes both the acid solution and the air dissolved in the acid solution, and even some of the air outside the acid solution.

[0054] The shell in the present invention refers to a steel shell or an aluminum-plastic film, wherein the shell of a soft-pack battery is generally made of an aluminum-plastic film.

[0055] The filter residue in the present invention is carbon black. This definition does not mean that it is 100% carbon black in an absolute sense, but most of it is carbon black.

[0056] Embodiment 1:

[0057] A method for recycling waste lithium-ion batteries by plasma ultrasound, comprising the following processes performed in sequence:

[0058] Vacuum deliquification process: first, empty the residual power of 50 waste lithium-ion batteries (i.e., lithium cobalt oxide 18650 cylindrical batteries), then put the waste lithium-ion batteries into a closed battery cutting box, then start the vacuum pump to continuously vacuum the battery cutting box, then cut and remove the shell of the waste lithium-ion battery to obtain the battery core, then, when the electrolyte is completely extracted by the vacuum pump, stop the vacuum operation, and then take the shell and the battery core out of the battery cutting box, the battery core includes the current collector and the active material, binder, and carbon black attached thereto;

[0059] Ultrasonic plasma process: first put the battery cell into a closed reaction box, which is equipped with an ultrasonic cavitation device and a plasma meter, and then transport an acid solution into the reaction box until the acid solution submerges the battery cell and the plasma meter, and then operate the acid solution with an ultrasonic cavitation device to generate cavitation bubbles, and then start the plasma meter to dissociate the gaseous molecules in the cavitation bubbles to generate highly active particles, and then the highly active particles collide with the active substances in the battery cell. After 20 minutes of reaction, there is no attachment on the current collector, and then turn off the plasma meter, and then discharge the powder-liquid mixture from the bottom of the reaction box. After the discharge, take out the current collector from the top or side of the reaction box (the positive current collector is aluminum foil, the negative current collector is copper foil, and the positive and negative current collectors are sandwiched with a diaphragm. After the reaction is completed, the three foils are taken out as a whole, and this foil as a whole only needs simple arrangement);

[0060] Post-recovery process: The powder-liquid mixture is filtered to obtain filter residue and filtrate, wherein the filter residue is carbon black and the filtrate is a solution of metal ions in the active substance; the post-recovery operation of the filter residue includes making negative electrode materials, and the recovery operation of the filtrate includes electrodepositing metals. In addition, the filtrate can be directly returned to the reaction box for recycling, or it can be returned to the reaction box for recycling after metals are electrodeposited, thereby completely avoiding the generation of waste liquid.

[0061] Embodiment 2:

[0062] The basic content is the same as that of Example 1, except that:

[0063] The waste lithium-ion batteries were 50 scrapped nickel-cobalt-manganese ternary 18650 cylindrical batteries, and the reaction time in the ultrasonic plasma process was 40 minutes.

[0064] Embodiment 3:

[0065] The basic content is the same as that of Example 1, except that:

[0066] The waste lithium-ion batteries were 50 scrapped lithium iron phosphate 18650 cylindrical batteries, and the reaction time in the ultrasonic plasma process was 10 minutes.

[0067] Embodiment 4:

[0068] The basic content is the same as that of Example 1, except that:

[0069] The waste lithium-ion batteries are 20 scrapped 20Ah ternary soft-pack batteries, and the reaction time in the ultrasonic plasma process is 40 minutes.

[0070] The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiment. Any equivalent modifications or changes made by ordinary technicians in this field based on the contents disclosed by the present invention should be included in the protection scope recorded in the claims.

Claims

1. A method for recycling waste lithium-ion batteries using plasma ultrasound. Features The method comprises the following processes performed sequentially: Vacuum dehydration process: firstly, the residual power of the waste lithium-ion battery is emptied, and then the waste lithium-ion battery is placed in a closed battery cutting box, and then the vacuum pump is started to continuously vacuum the battery cutting box, and then the shell of the waste lithium-ion battery is cut and removed to obtain the battery core, and then, when the electrolyte is completely extracted by the vacuum pump, the vacuum operation is stopped, and then the shell and the battery core are taken out from the battery cutting box, and the battery core includes the current collector and the active material, binder and carbon black attached thereto; Ultrasonic plasma process: first put the battery cell into a closed reaction box, which is equipped with an ultrasonic cavitation device and a plasma meter, and then transport an acid solution into the reaction box until the acid solution submerges the battery cell and the plasma meter, and then operate the acid solution with an ultrasonic cavitation device to generate cavitation bubbles, and then start the plasma meter to dissociate the gaseous molecules in the cavitation bubbles to generate highly active particles, and then the highly active particles collide with the active substances in the battery cell until there is no attachment on the current collector, and then turn off the plasma meter, and then discharge the powder-liquid mixture from the bottom of the reaction box. After the discharge, take out the current collector from the reaction box; Post-recovery process: filtering the powder-liquid mixture to obtain filter residue and filtrate, wherein the filter residue is carbon black and the filtrate is a solution of metal ions in the active substance; the post-recovery operation of the filter residue includes making negative electrode materials, and the recovery operation of the filtrate includes electrodepositing metals; In the ultrasonic plasma process, the acid solution is an organic acid or a mixture of an organic acid and an inorganic acid; and the pH value of the acid solution is 4-6.

2. A method for recycling waste lithium-ion batteries by plasma ultrasound according to claim 1, Features: After the metal ions in the filtrate in the post-recovery process are deposited, it is directly returned to the ultrasonic plasma process to be input into the reaction box and submerge the battery core together with the acid solution.

3. A method for recycling waste lithium-ion batteries by plasma ultrasound according to claim 1 or 2, Features: In the vacuum dehydration process, the operation of cutting the outer shell of the waste lithium-ion battery is completed by laser cutting.

4. A method for recycling waste lithium-ion batteries by plasma ultrasound according to claim 1 or 2, Features: In the vacuum dehydration process, the current collector includes a positive electrode current collector, a negative electrode current collector and a separator sandwiched therebetween.

5. A method for recycling waste lithium-ion batteries by plasma ultrasound according to claim 1 or 2, Features: In the ultrasonic plasma process, the components of the cavitation bubbles include water vapor and air; the highly active particles include hydrogen ions, peroxyl radicals and hydroxyl radicals.

6. A method for recycling waste lithium-ion batteries by plasma ultrasound according to claim 1 or 2, Features: In the ultrasonic plasma process, the active substance is any one of the following: When the lithium-ion battery is a lithium iron phosphate battery, the active material is LiFePO 4 ; When the lithium-ion battery is a lithium cobalt oxide battery, the active material is LiCoO 2 ; When the lithium-ion battery is a ternary battery, the active material is LiNi x Co y Mn 1-x-y O 2 .

7. A method for recycling waste lithium-ion batteries by plasma ultrasound according to claim 1 or 2, Features: In the vacuum dehydration process, when the waste lithium-ion batteries are placed in a closed battery cutting box, there are at least two types of waste lithium-ion batteries and at least two types of corresponding active materials.

8. A method for recycling waste lithium-ion batteries by plasma ultrasound according to claim 1 or 2, Features: In the ultrasonic plasma process, the binder is decomposed into carbon dioxide and water by highly active particles, and the carbon dioxide is collected and used for the recovery and preparation of lithium carbonate.

9. A method for recycling waste lithium-ion batteries by plasma ultrasound according to claim 1 or 2, Features: In the ultrasonic plasma process, while the powder-liquid mixture is being discharged, the ultrasonic cavitator is continuously operated until the liquid surface of the powder-liquid mixture is flush with the ultrasonic cavitator, and then the ultrasonic cavitator is closed.

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