Method for repairing and recycling waste battery positive electrode material

Abstract

The invention provides a method for repairing and recovering a positive electrode material of a waste battery, which adopts an electrochemical method, realizes efficient supplement or extraction of lithium in the positive electrode material of the waste battery in a water-based electrolyte, forms a lithium salt precipitate by adding an auxiliary agent, and realizes respective recovery of a lithium salt and a lithium-poor positive electrode material. Compared with an existing recovery technology, the method has the advantages of being easy and convenient to operate, low in energy consumption in the repairing process, low in cost and free of waste generation. Besides, different types of lithium battery materials can be recovered into lithium salt and lithium-poor positive electrode materials respectively, so that the detection of the content of residual lithium in active substances is avoided, the production process is simplified, and the production cost and time are reduced. The lithium extraction and lithium supplement processes of the positive electrode material can be completed in the same electrolytic tank, so that the voltage required by the reaction is reduced, the efficient utilization of energy is realized, the pH value of the electrolyte is balanced, the process cost is further reduced, and the production efficiency is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery material recycling, and in particular relates to a highly efficient repair and recycling method for battery electrode materials. Background Art

[0002] As one of the most important rechargeable batteries in the world today, lithium-ion batteries play a key role in promoting the development of electric vehicles, mobile devices and renewable energy. Their high energy density and long life make them an indispensable energy storage solution in modern life. However, with the widespread use of lithium-ion batteries, the problem of waste battery disposal is becoming increasingly serious.

[0003] Therefore, the importance of lithium-ion battery recycling technology is becoming increasingly prominent. Effective recycling can not only reduce the demand for limited resources and ease the pressure on mineral mining, but also reduce the pollution of toxic metals and chemicals to the environment. Efficient recycling can maximize the use of useful materials in waste batteries, reduce energy waste, and contribute to sustainable development and environmental protection goals. Therefore, the importance of lithium-ion batteries and their recycling technology is not only reflected in promoting scientific and technological innovation, but also in prompting us to manage and utilize this key energy storage technology more responsibly.

[0004] The existing recycling technologies for lithium-ion batteries are mainly divided into: hydrometallurgy, pyrometallurgy and direct recovery. Among them, hydrometallurgy and pyrometallurgy have high energy consumption, high pollutant emissions, high costs and will destroy the battery material structure, while the traditional direct recovery method can directly recover the electrode material without destroying the crystal structure of the electrode material, greatly reducing costs and energy consumption. The positive electrode active material of the battery obtained by the direct recovery method (the positive electrode active material of the battery is the key component involved in the electrochemical reaction in the battery, and it plays a vital role in the charging and discharging process. The positive electrode of the lithium-ion battery usually contains lithium compounds, such as lithium cobalt oxide (LiCoO2), lithium nickel cobalt manganese oxide (NCM) or lithium iron phosphate (LiFePO4)) usually needs to be repaired by calcination, that is, the active material, lithium salt and reducing agent are mixed and treated at high temperature to replenish the lithium content in the active material. However, this method has the problems of high energy consumption and high cost, and toxic and harmful gases and greenhouse gases (such as HF, CO2) are released during the heat treatment process. In addition, when recycling the positive active material of waste batteries, it is necessary to detect the residual lithium content to determine the amount of lithium salt and reducing agent to be added during the calcination repair process. Since the lithium content of different waste batteries varies greatly, each batch of batteries needs to be processed separately, which reduces the recycling efficiency and increases the detection cost. Therefore, it is difficult for existing methods to achieve low-energy consumption, low-cost, pollution-free and efficient recycling of waste battery materials with different charge states. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a method for repairing and recycling positive electrode materials of waste batteries. The method can achieve two results: (1) replenishing lithium: efficiently replenishing the missing lithium content in the positive electrode materials of waste batteries under low energy consumption conditions, thereby facilitating the subsequent reproduction of positive electrode materials. (2) extracting and recycling lithium: by extracting lithium elements from different types of positive electrode materials of waste batteries into a water-based electrolyte, and then adding an auxiliary agent to form a lithium salt precipitate, lithium salts and low-lithium-content lithium-poor positive electrode materials are obtained, thereby avoiding the detection of the remaining lithium content in the active substances of waste batteries during the recycling process. This simplifies the recycling process of different types of waste lithium batteries, improves production efficiency, and reduces production costs. In addition, these two effects can be achieved in the same electrolytic cell to balance the pH of the electrolyte while reducing the voltage required for the reaction, further shortening the recycling cycle and reducing costs.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] One of the technical solutions of the present application provides a method for repairing and recycling positive electrode materials of waste batteries, comprising the following steps:

[0008] The recycled positive electrode material of waste batteries is used as the electrode material in the electrolytic cell; a constant voltage or current is applied, and lithium ions in the electrode material on the anode side are extracted, and / or lithium ions on the cathode side are embedded in the electrode material; the current and voltage are continued to be applied, and the bubbles generated at the interface between the current collector and the active material during the electrolysis of water are used to achieve the stripping of the active material and the current collector, thereby obtaining the positive electrode material supplemented with lithium, and / or the lithium-deficient positive electrode material and the current collector; after the reaction, an auxiliary agent is added to the electrolytic cell to obtain lithium salt precipitation, thereby achieving comprehensive recovery of lithium-containing substances.

[0009] Furthermore, the positive electrode material recovered from waste batteries is the positive electrode plate of the waste batteries; the positive electrode plate comes from at least any one of lithium ion batteries, lithium sulfur batteries, sodium ion batteries, sodium sulfur batteries or potassium ion batteries.

[0010] Furthermore, the positive electrode material of the waste battery is used alone as the cathode / anode of the electrolytic cell, or is used simultaneously as the cathode and anode of the electrolytic cell; the said simultaneously being used as the cathode and anode of the electrolytic cell means that part of the positive electrode material recovered from the waste battery is used as the cathode, and part of it is used as the anode;

[0011] Furthermore, when the positive electrode material of the waste battery is used alone as the cathode / anode of the electrolytic cell, the other electrode of the electrolytic cell is a porous metal electrode; the porous metal electrode includes: any one of porous electrodes made of stainless steel, titanium, aluminum or nickel; the porous metal electrode is an electrode that does not participate in the electrochemical reaction and only serves as an electron transfer medium. They play a role in supporting the electrolyte and maintaining the voltage during the electrolysis or electroplating process.

[0012] Furthermore, the electrolytic cell includes, in addition to the cathode and the anode, at least a wire connected between the cathode and the cathode, an external power supply arranged on the wire, an electrolyte immersed in the cathode and cathode pole pieces, and an electrolytic cell containing the electrolyte;

[0013] The electrolytic cell is set up according to conventional technical solutions in the field; the wire is selected according to conventional operations of those skilled in the art, and is usually made of a metal with high conductivity, such as copper or aluminum; the voltage of the external power supply is 5-30V, and the electrode current density is 5-100mA / cm 2 , the external power supply is used to apply a constant voltage or current.

[0014] Furthermore, the electrolyte is a water-based electrolyte, the electrolyte of which is one or more of sulfate, bicarbonate, and nitrate, and one or more of lithium salt, sodium salt, potassium salt, and ammonium salt; the salt concentration of the electrolyte is 0.05-1.5 mol / L.

[0015] Furthermore, the auxiliary agent is at least any one of carbonate, phosphate, and fluoride, and is at least any one of sodium salt, potassium salt, and ammonium salt.

[0016] Furthermore, the method is carried out at normal temperature and pressure.

[0017] The second technical solution of the present application provides a regenerated positive electrode material, which is a lithium-supplemented positive electrode material obtained by the above method.

[0018] The third technical solution of the present application is to provide a lithium-poor positive electrode material obtained by the above method.

[0019] A fourth technical solution of the present application provides a battery comprising the above-mentioned regenerated positive electrode material.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The present invention uses an electrochemical method to replace the existing calcination method to repair and recycle the positive electrode materials of waste batteries. Compared with the prior art, the present method significantly reduces energy consumption and the use of chemical raw materials, and further significantly reduces the recycling cost.

[0022] (2) The repair process of the present invention does not require pretreatment of the electrodes removed from waste lithium-ion batteries, and lithium ions can be directly added to the lithium-deficient positive electrode materials in a water-based electrolyte, thereby greatly reducing the lithium-supplementing additives required for the subsequent reproduction of electrode materials. At the same time, ions can be extracted from positive electrode materials with unknown lithium content to obtain lithium-deficient positive electrode materials, eliminating the step of detecting the lithium content in the positive electrode materials during the recycling process, improving production efficiency, and simplifying the subsequent positive electrode material reproduction process.

[0023] (3) The present invention does not involve the treatment and recycling of waste gas and solid waste during the repair and recycling process, and the waste liquid generated only contains inorganic salts used for conductivity and electrolytes in the electrolyte of waste batteries. The electrolyte can be recovered by recrystallization, achieving efficient recovery of various components of waste batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The time-voltage curves of the repair and lithium extraction processes in Examples 1 and 3 of the present invention;

[0025] Figure 2 It is a flow chart of the electrode recovery process in the present invention;

[0026] Figure 3 The charge and discharge curves of the lithium iron phosphate battery before and after lithium supplementation in the present invention;

[0027] Figure 4 is a schematic diagram of an electrolysis device in the present invention;

[0028] The numbers in the figure indicate:

[0029] 1 is cathode, 2 is anode, 3 is wire, 4 is external power supply, 5 is electrolyte, and 6 is electrolytic cell. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below in conjunction with specific embodiments. It should be noted that the following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention. Although the steps in the present invention are arranged with numbers, they are not used to limit the order of the steps, unless the order of the steps is clearly stated or the execution of a certain step requires other steps as a basis, otherwise the relative order of the steps can be adjusted. It is understood that the term "and / or" used herein relates to and covers any and all possible combinations of one or more of the associated listed items.

[0031] All raw materials of the present invention have no particular limitation on their sources, and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0032] The metal porous electrode is a foam nickel electrode with a size of 1*20*20mm.

[0033] The waste batteries come from Shuangdeng Group Co., Ltd.

[0034] In Comparative Example 1 and Example 1, the lithium iron phosphate electrode is used as the cathode (positive electrode material) in the electrolytic cell, and the lithium ions on the cathode side will be embedded in the positive electrode material to obtain the positive electrode material after lithium supplementation.

[0035] In Examples 2, 4, and 5, the lithium iron phosphate electrode is used as the anode (negative electrode) in the electrolytic cell, and lithium ions are extracted from the positive electrode material on the anode side to obtain a lithium-poor positive electrode material and a current collector.

[0036] In Example 3, the lithium iron phosphate electrode serves as both the anode and the cathode in the electrolytic cell, and can simultaneously realize the extraction of lithium ions from the positive electrode material on the anode side and the embedding of lithium ions into the lithium ion positive electrode material on the cathode side, thereby obtaining a lithium-supplemented positive electrode material, a lithium-deficient positive electrode material and a current collector.

[0037] The specific configuration of the embodiment is shown in Table 1, and the flow chart of the electrode recovery process is shown in Table 1. Figure 2 The schematic diagram of the electrolysis device is shown in Figure 4 shown. Figure 4 In the method of the present invention, the electrode sheet placed on the cathode 1 side and the electrode sheet placed on the anode 2 side are connected to an external power supply 4 through a wire 3, and the electrode sheets are placed in an electrolytic cell 6 containing an electrolyte 5.

[0038] Table 1

[0039]

[0040] Comparative Example 1

[0041] Cut the waste lithium iron phosphate pole pieces in industrial production into 2*2cm 2 A small piece was used as the cathode of the water electrolysis electrolytic cell. The electrolytic cell uses 0.5 mol / L ammonium sulfate as the electrolyte, and a mixed metal oxide electrode mesh with the same area as the working electrode is used as the counter electrode. The electrolytic cell is then connected to a constant current power supply through a wire, and the power supply parameters are set to a current of 80 mA and a time of 24 s. After the above treatment, the positive electrode material can be separated from the aluminum foil by itself. After the experiment, the separated positive electrode material and the current collector are obtained. The obtained positive electrode material layer is washed with deionized water, crushed with a pulverizer, and then mixed with N-methylpyrrolidone at a mass ratio of 2:8 into a slurry, which is then coated on an aluminum foil for drying, and then rolled and cut into discs with a diameter of 12 mm, and assembled with lithium metal into a battery for charge and discharge tests at a current density of 15.5 mA / g.

[0042] Example 1

[0043] A highly efficient repair method for battery electrode materials comprises the following steps: cutting the positive electrode sheet of the recycled waste lithium iron phosphate battery into 2*2cm 2The electrolytic cell uses 0.5 mol / L ammonium sulfate and 0.1 mol / L lithium sulfate as the electrolyte, and uses a mixed metal oxide electrode mesh with the same area as the working electrode as the counter electrode. Then the electrolytic cell is connected to a constant current power supply through a wire, and the power supply parameters are set to 40 mA and 540 s. The voltage between the two electrodes of the electrolytic cell is measured by an electrochemical workstation, such as Figure 1 As shown, the reaction voltage gradually increased to 2.73 V during the lithium replenishment process and then tended to stabilize.

[0044] After the experiment, the separated lithium iron phosphate material and current collector were obtained. The obtained lithium iron phosphate material was washed with deionized water, crushed with a pulverizer, mixed with N-methylpyrrolidone at a mass ratio of 2:8 into a slurry, and then coated on aluminum foil for drying, then rolled and cut into 12mm diameter discs, and assembled with lithium metal into a battery for charge and discharge tests at a current density of 15.5mA / g.

[0045] Example 2

[0046] A highly efficient recycling method for battery electrode materials comprises the following steps: cutting the positive electrode sheet of the recycled waste lithium iron phosphate battery into 2*2cm 2 The small piece was used as the anode of the water electrolysis electrolytic cell. The electrolytic cell uses 0.5 mol / L ammonium sulfate as the electrolyte and a mixed metal oxide electrode mesh with the same area as the working electrode as the counter electrode. The electrolytic cell was then connected to a constant current power supply through a wire, and the power supply parameters were set to 32 mA and 1100 s. The lithium content of the lithium-poor lithium iron phosphate obtained after the reaction was measured to be 9% (Table 2).

[0047] Example 3

[0048] A highly efficient method for repairing and recycling battery electrode materials comprises the following steps: cutting the positive electrode sheet of the recycled waste lithium iron phosphate battery into 2*2cm 2 The small pieces were used as the cathode and anode of the water electrolysis electrolytic cell. The electrolytic cell used 0.5 mol / L ammonium sulfate and 0.1 mol / L lithium sulfate as electrolyte. The electrolytic cell was then connected to a constant current power supply through a wire, and the power supply parameters were set to 32 mA and 540 s. The voltage at both electrodes of the electrolytic cell was measured by an electrochemical workstation, such as Figure 1 As shown, the reaction voltage gradually increased to 2.18 V during the lithium replenishment process and then stabilized.

[0049] Example 4

[0050] A highly efficient recycling method for battery electrode materials comprises the following steps: cutting the recycled positive electrode sheet of nickel cobalt manganese oxide lithium battery into 2*2 cm 2A small piece of quartz crystal was used as the anode of the water electrolysis electrolytic cell. The electrolytic cell uses 0.5 mol / L sodium sulfate as the electrolyte, and a mixed metal oxide electrode mesh with the same area as the working electrode is used as the counter electrode. The electrolytic cell is then connected to a constant current power supply through a wire, and the power supply parameters are set to 50 mA and 1000 s. The lithium content of the lithium-poor nickel cobalt manganese oxide obtained after the reaction is measured to be 8% (Table 2).

[0051] Example 5

[0052] A highly efficient recycling method for battery electrode materials comprises the following steps: cutting the recycled positive electrode sheet of lithium cobalt oxide battery into 2*2cm 2 A small piece of lithium cobalt oxide was used as the anode of the water electrolysis electrolytic cell. The electrolytic cell uses 0.5 mol / L potassium sulfate as the electrolyte and a mixed metal oxide electrode mesh with the same area as the working electrode as the counter electrode. The electrolytic cell was then connected to a constant current power supply through a wire, and the power supply parameters were set to 60 mA and 800 s. The lithium content of the lithium-poor cobalt oxide obtained after the reaction was measured to be 10% (Table 2).

[0053] Experimental results:

[0054] like Figure 1 As shown, compared with using a mixed metal oxide electrode mesh for the counter electrode, using waste battery positive electrode sheets for both electrodes can significantly reduce the operating voltage, energy consumption and production costs.

[0055] like Figure 3 As shown, after lithium supplementation, the initial charging capacity of lithium iron phosphate increased from 112 mAh / g to 144 mAh / g, indicating that the method of the present invention can efficiently supplement the missing lithium content in the positive electrode material, which is beneficial to the subsequent electrode material reproduction process.

[0056] The results of the embodiment for obtaining lithium-poor positive electrode materials are shown in Table 2. After lithium extraction, the remaining lithium content of different materials is all within 9%, indicating that different types of positive electrode materials will not affect the lithium extraction efficiency of this method. Therefore, the present application can extract ions from positive electrode materials with unknown lithium content to obtain lithium-poor positive electrode materials with similar lithium content, eliminating the step of detecting the lithium content in the positive electrode material during the recycling process, improving production efficiency, and simplifying the subsequent positive electrode material reproduction process.

[0057] Table 2

[0058]

[0059] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for repairing and recycling positive electrode materials of waste batteries, characterized in that: The following steps are involved: The recycled waste battery positive electrode material is used as the electrode material in the electrolytic cell; a constant voltage or current is applied, and lithium ions in the electrode material on the anode side are extracted, and / or lithium ions on the cathode side are embedded in the electrode material; the current and voltage are continued to be applied to realize the stripping of the active material and the current collector, thereby obtaining the positive electrode material supplemented with lithium, and / or the lithium-deficient positive electrode material and the current collector; after the reaction, an auxiliary agent is added to the electrolytic cell to obtain a lithium salt precipitate, and the lithium-containing material is recovered; The recycled positive electrode material is a positive electrode plate of a waste battery; the positive electrode plate comes from at least any one of a lithium ion battery, a lithium sulfur battery, a sodium ion battery, a sodium sulfur battery or a potassium ion battery.

2. The method for repairing and recycling the positive electrode material of waste batteries according to claim 1, characterized in that: The positive electrode material of the waste battery is used as the cathode / anode of the electrolytic cell alone, or as the cathode and anode of the electrolytic cell at the same time; the simultaneous use as the cathode and anode of the electrolytic cell means that part of the positive electrode material recovered from the waste battery is used as the cathode and part as the anode.

3. The method for repairing and recycling the positive electrode material of waste batteries according to claim 1, characterized in that: When the waste battery positive electrode material is used alone as the cathode / anode of the electrolytic cell, the other electrode of the electrolytic cell is a porous metal electrode; the porous metal electrode is any one of the porous electrodes made of stainless steel, titanium, aluminum or nickel.

4. The method for repairing and recycling the positive electrode material of waste batteries according to claim 1, characterized in that: In addition to the cathode and the anode, the electrolytic cell also includes at least a wire connected between the cathode and the anode, an external power supply arranged on the wire, an electrolyte immersed in the cathode and anode pole pieces, and an electrolytic tank containing the electrolyte; The conductor is any one of copper and aluminum; The voltage of the external power supply is 5-30V, and the electrode current density is 5-100mA / cm 2 , the external power supply is used to apply a constant voltage or current.

5. The method for repairing and recycling the positive electrode material of waste batteries according to claim 4, characterized in that: The electrolyte is a water-based electrolyte, the electrolyte of which is one or more of sulfate, bicarbonate, and nitrate, and one or more of lithium salt, sodium salt, potassium salt, and ammonium salt; the salt concentration of the electrolyte is 0.05-1.5 mol / L.

6. The method for repairing and recycling the positive electrode material of waste batteries according to claim 1, characterized in that: The auxiliary agent is at least any one of carbonate, phosphate and fluoride, and is at least any one of sodium salt, potassium salt and ammonium salt.

7. The method for repairing and recycling the positive electrode material of waste batteries according to claim 1, characterized in that: The method is carried out at normal temperature and pressure.

8. A regenerated positive electrode material, characterized in that: The regenerated positive electrode material is a lithium-supplemented positive electrode material prepared by the method according to any one of claims 1 to 7.

9. A battery comprising the regenerated positive electrode material according to claim 8.

10. A lithium-deficient positive electrode material, characterized in that: The lithium-deficient positive electrode material is prepared by the method according to any one of claims 1 to 7.

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