A method for direct regeneration of waste lithium-ion battery positive electrode materials by electrochemical lithiation

Abstract

The present invention discloses a direct regeneration method for electrochemical lithiation of waste lithium-ion battery positive electrode materials. First, the waste lithium battery is disassembled to obtain positive electrode materials, graphite and a diaphragm. The positive electrode material and the graphite / platinum electrode constitute an electrochemical device, and a solution system containing a lithium additive dissolved in an aqueous solution, an ionic liquid or a low eutectic reagent is subjected to an electrochemical reaction. After the reaction, the positive electrode material is taken out and subjected to a two-step roasting process to obtain a repaired and regenerated positive electrode powder, which regenerates the electrochemical properties of the battery prepared by the positive electrode material.

Description

Technical Field

[0001] The present invention belongs to the field of industrial waste treatment and resource utilization in the field of environmental protection technology, and in particular relates to a method for direct regeneration of waste lithium-ion battery positive electrode materials by electrochemical lithiation, which is an environmentally friendly and efficient method for comprehensive recycling of waste lithium battery positive electrode materials. Background Art

[0002] In recent years, based on the requirements of energy sustainable development, safety and goal achievement, new energy vehicles have become a strategic emerging industry with a rapid market growth. Lithium-ion power batteries have become the core components of new energy vehicles. With the development of the new energy vehicle industry, the battle for lithium resources has intensified. At present, the recycling technology of lithium battery positive electrode materials is mainly based on traditional pyrometallurgy and hydrometallurgy. By destroying the chemical structure of the positive electrode material, metals and compounds of Li, Ni, Co and Mn are obtained. The recycling process has prominent problems such as high energy consumption, high recycling cost and secondary pollution. There are still many bottleneck problems in the safe discharge of waste lithium batteries, classification and separation of positive electrode materials and regeneration of metal resources that have not been solved. Therefore, the green, efficient and low-cost recycling of waste lithium batteries can not only generate high economic value, but also is an inevitable requirement to alleviate the contradiction between supply and demand of scarce resources in the world, promote the sustainable development of the new energy industry and protect the environment.

[0003] At present, the recycling methods of discarded lithium-ion batteries are mainly concentrated on hydrometallurgical technology (such as acid leaching, full dissolution, etc.) and pyrometallurgical technology (carbonization roasting reduction, chlorination volatilization, etc.). Hydrometallurgical technology usually converts metals such as Li, Ni, Co, and Mn into water-soluble ions through oxidation and complexation of chemical reagents in acidic or alkaline solutions, and then separates and extracts metal elements through chemical precipitation, ion exchange, extraction, adsorption, etc. These technologies have low recovery rates, consume a lot of reagents, and waste liquids need environmentally friendly treatment during application. If the lithium-deficient sites of discarded lithium batteries can be repaired, there is no need to decompose lithium positive electrode materials through chemical metallurgical methods. Summary of the invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a method for direct regeneration of waste lithium-ion battery positive electrode materials by electrochemical lithiation, that is, to directly regenerate the waste positive electrode materials by electrochemical lithiation of the waste lithium-ion battery positive electrode materials. The whole process is environmentally friendly, efficient, and has no secondary waste, thereby realizing the environmentally friendly, efficient, and low-cost reuse of waste lithium batteries.

[0005] The specific technical scheme for achieving the purpose of the present invention is as follows:

[0006] A method for direct regeneration of waste lithium-ion battery positive electrode materials by electrochemical lithiation, the method comprising the following steps:

[0007] ① Discharge and disassemble the discarded lithium-ion batteries to obtain the positive electrode material, negative electrode graphite and diaphragm of the lithium battery, and remove the positive electrode material;

[0008] ② The positive electrode material is heated at a temperature ranging from 100 to 600 o C for 1h~24h; after cooling, the lithium-containing positive electrode powder and aluminum sheet are screened out through a sieve; the lithium-containing positive electrode powder and new aluminum foil are passed through a tablet press to make a lithium-containing positive electrode tablet electrode; the lithium defect amount is determined by ICP-AES; the positive electrode tablet electrode is placed in an electrochemical device, and the positive electrode tablet electrode is used as a cathode, a graphite sheet or a platinum sheet is used as an anode, and a reference electrode is used to form an electrochemical device; wherein the positive electrode material includes lithium iron phosphate (LiFePO4), lithium manganese oxide (LiMn2O4), lithium cobalt oxide (LiCoO2), nickel cobalt manganese ternary material (LiNi x Co y Mn 1-x-y O2 (x: 0.01-0.99, y: 0.01-0.99)) and lithium nickel cobalt aluminum oxide (LiNi a Co b Al 1-a-b O2(a: 0.01-0.99, b: 0.01-0.99));

[0009] ③ Using one or more of LiX, LiOH, Li2CO3, LiNO3, Li3PO4, Li2SO4, Li2SO3, Li3BO3 and Li2O as lithium additives, where X is F, Cl, Br or I, and determining the content or addition ratio of the lithium additive according to the lithium defect amount in the positive electrode material, i.e., the lithium deficiency content range of 0.0001% to 99.9999%; if multiple lithium reagents are mixed and added, the addition compatibility and ratio are as follows: the addition ratio of LiX:LiOH is in the range of 1 to 30; the addition ratio of LiX:Li2SO4 is in the range of 1 to 20; the addition ratio of LiX:LiNO3 is in the range of 1 to 20; the ratio of LiX:Li3PO4 is in the range of 1 to 25; the ratio of LiX:Li2SO4 is in the range of 1 to 20; the ratio of LiX:Li2SO3 and LiX:Li3BO3 is in the range of 1 to 20;

[0010] ④ Dissolve the lithium additive in one or more eutectic reagents (choline chloride, imidazole, pyridine, urea, ethylene glycol, citric acid, glycerol). The ratio of lithium additive to eutectic reagent ranges from 0.1 to 100, and the ratio of eutectic reagent is as follows:

[0011] Choline chloride eutectic reagent ratio: Choline chloride (C5H 14The ratio of ClNO:urea (CON2H4) is in the range of 1 to 5, and the ratio of choline chloride (C5H 14 The ratio of ClNO:ethylene glycol (CH2OH)2) is in the range of 1 to 8, choline chloride (C5H 14 The ratio of ClNO:citric acid (C6H8O7) is in the range of 1 to 8, choline chloride (C5H 14 The ratio of ClNO):propylene glycol (C3H8O3) ranges from 1 to 5.

[0012] The ratio of imidazole eutectic reagents: imidazole (C3H4N2): urea (CON2H4) is in the range of 1~10, imidazole (C3H4N2): ethylene glycol (CH2OH)2 is in the range of 1~8, imidazole (C3H4N2): citric acid (C6H8O7) is in the range of 1~8, imidazole (C3H4N2): glycerol (C3H8O3) is in the range of 1~5.

[0013] The ratio of pyridine low eutectic reagents: pyridine (C5H5N): urea (CON2H4) is in the range of 1~10, the ratio of pyridine (C5H5N): ethylene glycol (CH2OH)2 is in the range of 1~8, the ratio of pyridine (C5H5N): citric acid (C6H8O7) is in the range of 1~8, and the ratio of pyridine (C5H5N): propylene glycol (C3H8O3) is in the range of 1~8.

[0014] The above-mentioned lithium additive and low eutectic reagent mixed solution was used for electrochemical constant current lithium insertion. The electrochemical reaction conditions were: the current range of the positive and negative electrodes was 0.0001A~1×10 5 A, lithium additive concentration range is 0.001mol / l~1×10 5 mol / l, reaction time range is 1min ~1000h, temperature is controlled at 0~500 o C, stirring speed range is 10-1000 r / min.

[0015] ⑤ After the electrochemical reaction, the lithium-ionized positive electrode sheet is taken out and placed in a muffle furnace. The calcination mode is further adopted to reduce the crystal structure of the positive electrode powder. The positive electrode powder is then heated to 500-1200 °C. o C for 2h~24h to obtain a repaired and regenerated positive electrode lithium-containing powder; the regenerated positive electrode powder, aluminum sheet and organic adhesive are coated to obtain a regenerated positive electrode material.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) This method is simple to operate and easy to implement. It can directly regenerate waste lithium battery positive electrode materials without using traditional chemical metallurgical methods, which will greatly reduce the recycling process cost and subsequent environmental protection costs.

[0018] (2) This method is applicable to the repair of all lithium battery positive electrode materials. The repair rate is improved, the energy consumption is reduced, and the charge and discharge performance of the battery prepared by the repaired positive electrode powder reaches the level of a new battery. Compared with the traditional wet method for recycling lithium batteries, this method has significant advantages. The present invention overcomes the problems of complex process, low recovery rate and large amount of waste acid and wastewater in the traditional wet method for recycling lithium battery positive electrode materials.

[0019] (3) It is highly efficient, environmentally friendly, and highly resource-efficient, making it suitable for large-scale industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a morphology diagram of the regenerated positive electrode material of the present invention. DETAILED DESCRIPTION Example

[0021] First, the discarded lithium batteries are discharged and disassembled to obtain lithium-containing positive electrode materials. The materials are calcined at a temperature range of 450 oC for 12 hours. After cooling, the positive electrode powder and aluminum sheet are sieved out through a sieve. The lithium-containing positive electrode powder and new aluminum foil are passed through a tablet press to make a lithium-containing positive electrode pressed electrode. The lithium defect content is determined to be 0.045% by ICP-AES. The positive electrode material is placed in an electrochemical device, with the positive electrode material as the cathode, a graphite sheet or a platinum sheet as the anode, and a reference electrode as an auxiliary to form an electrochemical device. LiCl is used as a lithium additive, and the content of the lithium additive is determined according to the amount of lithium defects in the positive electrode material. The lithium additives LiCl and LiOH (in a ratio of 1:5) are dissolved in a low eutectic reagent (choline chloride (C5H 14 The electrochemical constant current lithium insertion was carried out in a solution of 1:5 (ClNO):ethylene glycol (CH2OH)2) with a current density of 0.5 mA / cm 2 After the electrochemical reaction, the lithium-ionized electrode sheet was taken out and placed in a muffle furnace. The calcination mode was further adopted to reduce the crystal structure of the positive electrode powder. The positive electrode powder was then heated to 900 °C. o C for 12 hours to obtain the repaired and regenerated positive electrode lithium-containing powder. The regenerated positive electrode powder, aluminum sheet and organic adhesive are coated to obtain a regenerated positive electrode material; its morphology is shown in Figure 1 shown. Example

[0022] First, the discarded lithium batteries are discharged and disassembled to obtain lithium-containing positive electrode materials. oC for 8 hours. After cooling, the positive electrode powder and aluminum sheet are separated by a sieve. The lithium-containing positive electrode powder and aluminum foil are passed through a tablet press to make a lithium-containing positive electrode pressed electrode. By ICP-AES, the lithium defect content is determined to be 0.07%. . The positive electrode material is placed in an electrochemical device, with the positive electrode material as the cathode, the graphite sheet or platinum sheet as the anode, and a reference electrode as an auxiliary to form an electrochemical device. LiCl:LiOH=5 is used as a lithium additive, and the content of the lithium additive is determined according to the lithium defect content in the positive electrode material. The multi-lithium salt reagent with the addition ratio of lithium additives LiCl, Li2SO4, and LiNO3 in the range of 1:10:10 is added to the pyridine (C5H5N): citric acid (C6H8O7) solvent in the range of 1:7, and the electrochemical constant current lithium insertion is carried out, and the current density is 0.5 mA / cm 2 After the electrochemical reaction, the lithium-ionized electrode sheet was taken out and placed in a muffle furnace. The calcination mode was further adopted to reduce the crystal structure of the positive electrode powder. The positive electrode powder was then heated to 900 °C. o C for 12 h to obtain a repaired and regenerated positive electrode lithium-containing powder. The regenerated positive electrode powder, aluminum sheet and organic adhesive are coated to obtain a regenerated positive electrode material.

[0023] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all such improvements and changes should belong to the claims attached to the present invention.

Claims

1. A method for direct regeneration of waste lithium-ion battery positive electrode materials by electrochemical lithiation, characterized in that: The method comprises the following steps: ① Discharge and disassemble the discarded lithium-ion batteries to obtain the positive electrode material, negative electrode graphite and diaphragm of the lithium battery, and remove the positive electrode material; ② The positive electrode material is heated at a temperature ranging from 100 to 600 o C for 1 h to 24 h; after cooling, the lithium-containing positive electrode powder and aluminum sheet are screened out through a sieve; the lithium-containing positive electrode powder and new aluminum foil are passed through a tablet press to make a lithium-containing positive electrode tablet electrode; the lithium defect amount is determined by ICP-AES; the positive electrode tablet electrode is placed in an electrochemical device, and the positive electrode tablet electrode is used as a cathode, a graphite sheet or a platinum sheet is used as an anode, and a reference electrode is used to form an electrochemical device; wherein the positive electrode material includes lithium iron phosphate, namely LiFePO4, lithium manganese oxide, namely LiMn2O4, lithium cobalt oxide, namely LiCoO2, and a nickel-cobalt-manganese ternary material LiNi x Co y Mn 1-x-y O2 and LiNi a Co b Al 1-a-b O2; where: x: 0.01-0.99, y: 0.01-0.99; a: 0.01-0.99, b: 0.01-0.99; ③ Using one or more of LiX, LiOH, Li2CO3, LiNO3, Li3PO4, Li2SO4, Li2SO3, Li3BO3 and Li2O as lithium additives, where X is F, Cl, Br or I, and determining the content or addition ratio of the lithium additive according to the lithium defect amount in the positive electrode material, i.e., the lithium deficiency content range of 0.0001% to 99.9999%; if multiple lithium reagents are mixed and added, the addition compatibility and ratio are in the range of 1 to 30 for LiX:LiOH; 1 to 20 for LiX:Li2SO4; 1 to 20 for LiX:LiNO3; 1 to 20 for LiX:Li3PO4; 1 to 25 for LiX:Li2SO4; 1 to 20 for LiX:Li2SO3 and LiX:Li3BO3; ④ Dissolve the lithium additive in one or more eutectic reagents of choline chloride, imidazole, pyridine, urea, ethylene glycol, citric acid and glycerol; the ratio of the lithium additive to the eutectic reagent is in the range of 0.1 to 100, and the eutectic reagent ratio is as follows: Choline chloride eutectic reagent ratio: Choline chloride C5H 14 The ratio of ClNO: urea CON2H4 ranges from 1 to 5, and the ratio of choline chloride C5H 14 The ratio of ClNO:ethylene glycol (CH2OH)2 ranges from 1 to 8, choline chloride C5H 14 The ratio of ClNO: citric acid C6H8O7 is in the range of 1 to 8, and choline chloride C5H 14 The ratio of ClNO: glycerol C3H8O3 ranges from 1 to 5; The ratio of imidazole eutectic reagents: imidazole C3H4N2: urea CON2H4 is in the range of 1-10, imidazole C3H4N2: ethylene glycol (CH2OH)2 is in the range of 1-8, imidazole C3H4N2: citric acid C6H8O7 is in the range of 1-8, imidazole C3H4N2: glycerol C3H8O3 is in the range of 1-5; The ratio of pyridine eutectic reagents: the ratio of pyridine C5H5N: urea CON2H4 is in the range of 1-10, the ratio of pyridine C5H5N: ethylene glycol (CH2OH)2 is in the range of 1-8, the ratio of pyridine C5H5N: citric acid C6H8O7 is in the range of 1-8, and the ratio of pyridine C5H5N: glycerol C3H8O3 is in the range of 1-8; The lithium additive and the low eutectic reagent mixed solution are used for electrochemical constant current lithium insertion. The electrochemical reaction conditions are: the current range of the positive and negative electrodes is 0.0001A~1×10 5 A, lithium additive concentration range is 0.001mol / l~1×10 5 mol / l, the concentration range of eutectic reagent is 5 mol / l~1×10 5 The reaction time range is 1min ~1000h, and the temperature is controlled at 0~500 o C, stirring speed range is 10-1000 r / min; ⑤ After the electrochemical reaction, the lithium-ionized positive electrode sheet is taken out and placed in a muffle furnace. The calcination mode is further adopted to reduce the crystal structure of the positive electrode powder. The positive electrode powder is then heated to 500-1200 °C. o C for 2h~24h to obtain a repaired and regenerated positive electrode lithium-containing powder; the regenerated positive electrode powder, aluminum sheet and organic adhesive are coated to obtain a regenerated positive electrode material.

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