Method for preparing cup2@nc by using retired lithium ion battery negative copper foil and application thereof

Abstract

The application belongs to the field of waste utilization and electrode technology, and relates to a method for preparing CuP2@NC by using negative copper foil of a retired lithium ion battery and application, comprising the following steps: 1) recovering copper foil: recovering copper foil from the retired lithium ion battery through disassembly, sorting and ball milling; 2) preparing CuP2@NC samples: taking a carbon source, red phosphorus and the copper foil of step 1), and mixing according to a mass ratio of copper:carbon:red phosphorus of 1:1:1-1:3:2, and obtaining under plasma ball milling in a nitrogen atmosphere; and 3) carbonizing to obtain CuP2@NC nanoparticles. The application prepares CuP2@NC nanoparticles from the copper foil recovered from the retired lithium ion battery through sorting and ball milling, does not need high-temperature reduction of copper single elements, greatly reduces energy consumption, realizes resource recycling, and the prepared CuP2@NC nanoparticles have good electronic conductivity and can be used as negative electrode material of a sodium ion battery.

Description

Technical Field

[0001] This invention belongs to the fields of waste utilization and electrode technology, and relates to a method and application for preparing CuP2@NC using copper foil from the negative electrode of retired lithium-ion batteries. Background Technology

[0002] To achieve sustainable development, the major strategic goals of "carbon peaking" and "carbon neutrality" have been proposed. Lithium-ion batteries, with their advantages of high energy density, small size, long lifespan, and environmental friendliness, have been widely used in daily life. Therefore, lithium-ion batteries undoubtedly occupy an important position in the major strategy of achieving the "dual carbon" goals. However, the increasing number of retired and used lithium-ion batteries has brought serious waste management challenges. Aluminum current collectors (aluminum foil) and copper current collectors (copper foil) are important components of lithium-ion batteries, accounting for more than 15% of the battery's weight. Directly discarding them results in resource waste and environmental pollution; at the same time, producing new current collectors requires energy consumption, increasing costs.

[0003] Sodium is abundant, inexpensive, and shares similar chemical properties with lithium. Therefore, sodium-ion batteries are considered a promising energy storage device for large-scale application, potentially replacing lithium-ion batteries. Sodium-ion batteries operate on the same mechanism as lithium-ion batteries, but the radius of sodium ions differs. Specific radius of lithium ions Due to thermodynamic and kinetic limitations, traditional graphite anodes for lithium-ion batteries cannot meet the requirements of sodium-ion battery anodes. Therefore, developing sodium-ion battery anodes with high specific energy is essential.

[0004] Among the current numerous sodium-ion battery negative electrode researches, transition metal phosphides are considered as potential negative electrode materials for sodium-ion batteries due to their extremely high theoretical specific capacity and low redox potential. The preparation methods of transition metal phosphides include: patent CN201811104179.X discloses a phosphorus-based negative electrode material for sodium-ion batteries and a preparation method. The phosphorus-based negative electrode material is prepared by adding 5-propionamido isophthalic acid and copper nitrate as raw materials to an imidazole aqueous solution, evaporating and crystallizing to obtain a copper-based metal-organic framework, and then compounding and carbonizing with phosphorus to form a porous carbon-based skeleton conductive network connected copper phosphide; for example, Yan Yu et al. prepared Cu3(PO4)2·3H2O nanosheets using copper acetate trihydrate and ammonium dihydrogen phosphate as raw materials and water and ethanol as solvents, obtained C-Cu3(PO4)2·3H2O after coating with dopamine hydrochloride, and finally obtained CuP2 composite packaged by cross-linked hollow carbon sheets (CHCS-CuP2) after reduction by Ar / H2 mixed gas and phosphorization using red phosphorus as a phosphorus source. The CHCS-CuP2 prepared by this method exhibits good conductivity and capacity retention when used as a negative electrode of a sodium-ion battery (ACS Nano 2018, 12, 7018-7027); in addition, patent CN201610452201.4 discloses a transition metal phosphide / porous carbon composite material used as a negative electrode material for sodium-ion batteries. The precursor of the transition metal phosphide / porous carbon composite material is prepared by using transition metal salt and organic ligand as raw materials in an organic solvent at 150-200 DEG C for 12-24 h to obtain a metal-organic framework, then using inorganic phosphorus as a phosphorus source, inert gas as a protective gas, and heating to 300-700 DEG C to obtain a transition metal phosphide, which is used as a negative electrode material for sodium-ion batteries.

[0005] In summary, the main method for synthesizing copper phosphide negative electrode material precursor at present is to synthesize metal-organic frameworks or nanomaterials containing divalent copper ions, and then to obtain elemental copper by Ar / H2 mixed gas reduction at high temperature and then to phosphorize. Although this method can achieve the preparation of copper phosphide negative electrode material, it has the following problems: high temperature or H2 reduction is often required during synthesis, the preparation system requires high energy consumption, which is contrary to the “double carbon” strategic goal, the reaction time is long, and organic solvents are used, which pollutes the environment. Therefore, it is very meaningful to develop a low-energy-consumption, high economic and social benefit method to prepare copper phosphide nanomaterials. SUMMARY

[0006] In order to solve the technical problems of resource waste caused by retired lithium batteries and high energy consumption of sodium-ion electrode materials, the application provides a method for preparing CuP2@NC by using retired lithium-ion battery negative electrode copper foil and application thereof.

[0007] The application prepares CuP2@NC nanoparticles from the copper foil recovered from the retired lithium ion battery by the method of sorting and ball milling, without high-temperature reduction of copper element, greatly reduces energy consumption, and realizes resource recycling; the prepared CuP2@NC nanoparticles have good electronic conductivity and can be used as a negative electrode material of a sodium ion battery.

[0008] A method for preparing CuP2@NC from retired lithium ion battery negative copper foil, comprising the following steps:

[0009] 1) Recovering copper foil

[0010] The copper foil is recovered from the retired lithium ion battery by disassembling, sorting and ball milling;

[0011] 2) Preparing CuP2@NC sample

[0012] The carbon source, red phosphorus and the copper foil of step 1) are taken and mixed according to the mass ratio of copper foil: carbon source: red phosphorus 1:1:1-1:3:2, and CuP2@NC sample is obtained by plasma ball milling under nitrogen atmosphere;

[0013] 3) Carbonization

[0014] The above CuP2@NC sample is carbonized to obtain CuP2@NC nanoparticles.

[0015] Further limitation, in step 2), the carbon source is glucose, dopamine hydrochloride or stearic acid.

[0016] Further limitation, in step 2), the time of plasma ball milling is 6h-8h.

[0017] Further limitation, the specific process of recovering copper foil in step 1) is:

[0018] 1.1) The retired lithium ion battery is sequentially discharged, disassembled and sorted to obtain a negative electrode material;

[0019] 1.2) The negative electrode material of step 1.1) is sorted and ball milled under nitrogen atmosphere to obtain copper foil.

[0020] Further limitation, in step 1.1), salt water is used for discharging, and the concentration of the salt water is 2mol / L.

[0021] Further limitation, in step 1.2), the ball milling includes primary ball milling and secondary ball milling; the primary ball milling is normal temperature ball milling or high temperature ball milling, and the primary ball milling time is 6h-8h; the high temperature ball milling temperature is 400℃-600℃, and the secondary ball milling time is 6h-8h; sorting is performed after each ball milling.

[0022] Further limited, the carbonization condition of step 3) is: the carbonization temperature is 500 DEG C, and the carbonization time is 2h.

[0023] The CuP2@NC nanoparticles are prepared by the method of preparing CuP2@NC from the retired lithium ion battery negative copper foil.

[0024] The CuP2@NC nanoparticles are used as an anode in a sodium ion battery.

[0025] Further limited, the CuP2@NC nanoparticles used as an anode in the sodium ion battery have a first coulombic efficiency of 81.7%.

[0026] Compared with the prior art, the application has the beneficial effects that:

[0027] 1. The preparation method of the application uses retired waste lithium ion battery negative copper foil as raw material, avoids energy consumption and emission caused by Ar / H2 high-temperature reduction of copper single element, greatly reduces energy consumption, realizes recycling of waste resources, and has significant economic and social benefits.

[0028] 2. The application uses a continuous ball milling method to prepare CuP2@NC nanoparticles from retired lithium ion battery negative copper foil, and the whole preparation process is simple, the ball milling time is short, the conditions are mild, safe, and the raw materials are cheap and easy to obtain, the equipment requirement is low, and mass production is easy.

[0029] 3. The CuP2@NC nanoparticles prepared by the preparation method of the application have good electronic conductivity, and the nitrogen-doped carbon shell effectively limits the volume expansion during sodium intercalation, thereby greatly improving the cycle performance; when used as a negative electrode of a sodium ion battery, it can exhibit high first coulombic efficiency and discharge specific capacity, meeting the demand of electrode materials.

[0030] 4. The application provides a method for preparing a negative electrode of a sodium ion battery from retired waste lithium ion battery negative copper foil, which has great application and research prospects in the preparation and sodium storage performance of the negative electrode of the sodium ion battery. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The process flow chart for preparing CuP2@NC from retired lithium ion battery negative copper foil of the application;

[0032] Figure 2 The SEM image of copper prepared in Example 4;

[0033] Figure 3 The XRD image of CuP2@NC nanoparticles prepared in Example 8;

[0034] Figure 4 The SEM image of nitrogen-doped carbon-coated copper phosphide nanoparticles prepared in Example 8;

[0035] Figure 5 is a TEM image of nitrogen-doped carbon-coated copper diphosphide nanoparticles prepared in Example 8;

[0036] Figure 6 is a cyclic voltammogram of CuP2@NC nanoparticles prepared in Example 8;

[0037] Figure 7 is the electrochemical performance of nitrogen-doped carbon-coated copper diphosphide obtained under different ball milling states. DETAILED DESCRIPTION

[0038] The present application will be further described in conjunction with the examples and drawings, so that the advantages and features of the present application can be more easily understood by those skilled in the art, and the scope of protection of the present application can be more clearly defined.

[0039] Reference Figure 1 The method for preparing CuP2@NC using retired lithium-ion battery negative copper foil provided by the present application comprises the following steps.

[0040] 1) Recovering copper foil

[0041] The copper foil is recovered from the retired lithium-ion battery by disassembling, sorting and ball milling.

[0042] Specifically, the process of recovering the copper foil is.

[0043] 1.1) The retired lithium-ion battery is sequentially discharged, disassembled and sorted to obtain negative electrode material.

[0044] In this step, the salt water is discharged for 2 days, and the concentration of the salt water is 2 mol / L.

[0045] 1.2) The negative electrode material of step 1.1) is ball milled and sorted under a nitrogen atmosphere to obtain copper foil.

[0046] In this step, the ball milling includes primary ball milling and secondary ball milling.

[0047] The purpose of the primary ball milling is to preliminarily remove the binder and negative electrode powder.

[0048] The primary ball milling is high-temperature ball milling or normal-temperature ball milling, and the ball milling time is 6h-8h.

[0049] The temperature of the high-temperature ball milling is 400℃-600℃.

[0050] The purpose of the secondary ball milling is to remove the residual binder and negative electrode powder on the surface and the part of copper corroded by the electrolyte through physical and chemical reactions. The secondary ball milling is conventional ball milling or high-energy ball milling, and the ball milling time is 6h-8h.

[0051] Specifically, after each stage of ball milling, sorting is performed.

[0052] 2) Preparation of CuP2@NC sample

[0053] The carbon source, red phosphorus, and copper foil of step 1) are taken and mixed in a mass ratio of copper:carbon:red phosphorus of 1:1:1-1:3:2 to obtain a CuP2@NC sample by plasma ball milling under a nitrogen atmosphere.

[0054] In this step, the carbon source is glucose, dopamine hydrochloride, or stearic acid.

[0055] Preferably, the carbon source is glucose.

[0056] In this step, the time of plasma ball milling is 6-8 h.

[0057] 3) Carbonization

[0058] The above CuP2@NC sample is carbonized to obtain CuP2@NC nanoparticles. The carbonization conditions are: carbonization temperature is 500°C, and carbonization time is 2 h.

[0059] The examples described below by means of the attached drawings are exemplary and are intended to serve as an explanation of the present application and cannot be understood as a limitation thereof.

[0060] In the following examples, the operation methods used, such as sorting, mixing, etc., are all conventional technical means in the art. In the following examples, the reagents and chemicals used are all analytical pure purchased from the market.

[0061] Example 1

[0062] The method for preparing CuP2@NC using retired lithium-ion battery negative copper foil provided in this embodiment comprises the following steps.

[0063] 1) Recovering copper foil from retired lithium-ion battery

[0064] 1.1) Discharge the retired lithium-ion battery. Remove the outer packaging of the single retired lithium-ion battery to expose the aluminum shell, and then place it in a 5L sodium chloride solution with a concentration of 2 mol / L for 2 days of discharge.

[0065] 1.2) Disassemble and sort the discharged battery to obtain the negative electrode. Sort the electrode material of the disassembled and broken waste lithium battery, and use foam sorting to divide it into waste positive electrode material and waste negative electrode material according to their different physical and chemical properties.

[0066] 1.3) Under a nitrogen atmosphere, the negative electrode material is placed in a normal temperature ball mill for ball milling for 8 h to preliminarily remove the binder and negative electrode powder, and sorting to obtain a primary copper foil.

[0067] 1.4) The obtained primary copper foil is placed in a conventional ball mill under a nitrogen atmosphere for 8 h, and the surface residual binder and negative electrode powder and the part of the copper foil corroded by the electrolyte are removed by physical and chemical reactions while the copper foil is pulverized, and then the copper foil is separated by a density separation screen.

[0068] 2) Preparation of CuP2@NC sample

[0069] 100 mg of copper, 100 mg of carbon source, and 100 mg of red phosphorus are respectively placed in a glove box, mixed uniformly, loaded into a ball mill tank, and placed in a plasma ball mill under a nitrogen atmosphere for 8 h to obtain a CuP2@NC sample.

[0070] In this embodiment, the carbon source is glucose.

[0071] 3) Carbonization

[0072] The above-prepared CuP2@NC sample is placed in a tube furnace and argon is introduced for carbonization, the carbonization temperature is 500°C, and the carbonization time is 2 h to obtain CuP2@NC nanoparticles.

[0073] Example 2

[0074] The method for preparing CuP2@NC using the negative copper foil of the retired lithium ion battery provided in this embodiment is the same as that in Example 1, except that the high-temperature ball milling in step 1.3) is at a temperature of 600°C.

[0075] Example 3

[0076] The method for preparing CuP2@NC using the negative copper foil of the retired lithium ion battery provided in this embodiment is the same as that in Example 1, except that the high-energy ball mill is used in step 1.4).

[0077] Example 4

[0078] The method for preparing CuP2@NC using the negative copper foil of the retired lithium ion battery provided in this embodiment is the same as that in Example 3, except that the high-temperature ball milling in step 1.3) is at a temperature of 600°C.

[0079] Example 5

[0080] The method for preparing CuP2@NC using the negative copper foil of the retired lithium ion battery provided in this embodiment is the same as that in Example 1, except that 100 mg of copper, 300 mg of carbon source, and 200 mg of red phosphorus are used.

[0081] Example 6

[0082] The method for preparing CuP2@NC by using the negative copper foil of the retired lithium ion battery provided in this embodiment is the same as that in embodiment 2, except that 100 mg of copper, 300 mg of carbon source and 200 mg of red phosphorus are used.

[0083] Example 7

[0084] The method for preparing CuP2@NC by using the negative copper foil of the retired lithium ion battery provided in this embodiment is the same as that in embodiment 3, except that 100 mg of copper, 300 mg of carbon source and 200 mg of red phosphorus are used.

[0085] Example 8

[0086] The method for preparing CuP2@NC by using the negative copper foil of the retired lithium ion battery provided in this embodiment is the same as that in embodiment 4, except that 100 mg of copper, 300 mg of carbon source and 200 mg of red phosphorus are used.

[0087] The CuP2@NC nanoparticles prepared in the application are nitrogen-doped carbon-coated copper diphosphide nanoparticles, and the performance thereof is verified through the following experiments.

[0088] Verification test 1

[0089] The copper foil obtained through high-temperature and high-energy ball milling in embodiment 4 is taken to determine the SEM image, and the result is shown in Figure 2 .

[0090] Referring to Figure 2 It can be seen that the obtained copper particles are relatively uniform, and the surface is also relatively smooth.

[0091] Verification test 2 XRD image

[0092] The XRD image of the CuP2@NC nanoparticles prepared in embodiment 8 is tested. The result is shown in Figure 3 .

[0093] Through Figure 3 It can be seen that the obtained copper diphosphide belongs to a monoclinic phase, wherein the crystal face completely corresponds to the crystal face of the standard card (JCPDS No. 76-1190 CuP2), indicating that pure-phase copper diphosphide is synthesized by using the continuous ball milling method.

[0094] Verification test 3

[0095] The SEM of the nitrogen-doped carbon-coated copper diphosphide obtained in embodiment 8 is shown in Figure 4 It can be seen that the obtained nitrogen-doped carbon-coated copper diphosphide nanoparticles are relatively uniform, small in size and basically nanosized.

[0096] Verification test 4

[0097] The TEM of the obtained nitrogen-doped carbon-coated copper diphosphide is as followsFigure 5 It can be seen that the carbon layer uniformly coats the copper phosphide, which effectively limits the volume expansion caused by sodium insertion and inhibits the capacity decay caused by the structural damage of the copper phosphide.

[0098] Verification Test 5

[0099] The CuP2@NC nanoparticles prepared in Example 8 were mixed with a conductive agent, acetylene black, and a binder (CMC, sodium carboxymethyl cellulose) at a mass ratio of 8:1:1, and then a proper amount of ultrapure water was added as a solvent, and the mixture was stirred uniformly. The obtained slurry was coated on an aluminum foil, which was dried at 120°C for 10h under vacuum, and then a round sheet with a diameter of 14mm was punched out by a sheet punching machine, and was compacted under a pressure of 10Mpa to obtain a positive sheet of a button cell.

[0100] In an argon-filled glove box, a button cell was prepared according to the order of assembly of a button cell, with a metal sodium foil as a negative electrode, 1mol / L NaPF6 DME as an electrolyte, and a glass fiber separator (GF / D).

[0101] In this example, a BTS test system of Shenzhen Neware Company was used to perform constant current charge and discharge tests at room temperature at 0.01V-2.5V, and a CHI660e produced by Shanghai Chenhua Company was used to perform cyclic voltammetry tests. The mechanism of the assembled battery was discussed by cyclic voltammetry, the test voltage window was 0.01V-2.5V, and the scan rate was 0.1mV / s. -1 The obtained cyclic voltammogram is shown in Figure 6 .

[0102] Referring to Figure 6 , there are two wide reduction peaks near 0.35V and 0.01V in the cathode scan, which is due to the generation of Cu and Na3P from the multi-step sodium reaction of copper phosphide. In the subsequent anode scan, two wide peaks appear at 0.65 and 0.88V, showing a reversible desodium process. After the first cycle, the CV curve overlaps and remains stable, showing great stability.

[0103] Verification Test 6

[0104] The CuP2@NC samples prepared in Example 1, Example 2, Example 3 and Example 4 under different ball milling states were taken.

[0105] According to the test method of Verification Test 5, the electrochemical performance of the nitrogen-doped carbon-coated copper phosphide (i.e. CuP2@NC sample) obtained under different ball milling states was obtained, and the results are shown in Figure 7 .

[0106] From Figure 7It can be seen that the electrochemical performance of the nitrogen-doped carbon-coated copper phosphide obtained by high-temperature high-energy ball milling is the most stable, the first coulombic efficiency is 88.7%, and the discharge specific capacity is 502.8 mAh g -1 at 0.1 A g -1 after 80 cycles; this is due to the high nanocrystallization of copper phosphide and the advantages of carbon coating caused by the interaction between high-temperature high-energy and plasma ball milling. At the same time, this fully shows that the nitrogen-doped carbon-coated copper phosphide prepared by the application has excellent cycle performance when applied to sodium ion batteries, and is a promising negative electrode material for sodium ion batteries.

[0107] Obviously, the described embodiments are only part of the embodiments of the application, not all the embodiments, and all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the application.

Claims

1. A method for preparing CuP2@NC using copper foil from the negative electrode of a retired lithium-ion battery, characterized by comprising the following steps: 1) Recycling copper foil Copper foil is recovered from retired lithium-ion batteries through dismantling, sorting, and ball milling. The specific process for recycling copper foil in step 1) is as follows: 1.1) Retired lithium-ion batteries are sequentially discharged, disassembled, and sorted to obtain negative electrode materials; 1.2) Under a nitrogen atmosphere, the negative electrode material from step 1.1) is sorted and ball-milled to obtain copper foil; The ball milling includes a primary ball milling and a secondary ball milling; the primary ball milling is either a room temperature ball milling or a high temperature ball milling, and the primary ball milling time is 6h-8h; the high temperature ball milling temperature is 400℃-600℃, and the secondary ball milling time is 6h-8h; 2) Preparation of CuP2@NC samples Take carbon source, red phosphorus and copper foil from step 1), and mix them according to the mass ratio of copper foil: carbon source: red phosphorus of 1:1:1 to 1:3:

2. Then, obtain CuP2@NC sample by plasma ball milling under nitrogen atmosphere. In step 2), the carbon source is glucose, dopamine hydrochloride, or stearic acid; 3) Carbonization The CuP2@NC sample was carbonized to obtain CuP2@NC nanoparticles.

2. The method for preparing CuP2@NC using copper foil from the negative electrode of a retired lithium-ion battery according to claim 1, characterized in that, In step 2), the plasma ball milling time is 6-8 hours.

3. The method for preparing CuP2@NC using retired lithium-ion battery negative electrode copper foil according to claim 1, characterized in that, Step 1.1) involves saline discharge with a concentration of 2 mol / L and a volume of 5 L, lasting for 2 days.

4. The method for preparing CuP2@NC using copper foil from the negative electrode of a retired lithium-ion battery according to claim 1, characterized in that, In step 1.2), sorting is performed after each stage of ball milling.

5. The method for preparing CuP2@NC using copper foil from the negative electrode of a retired lithium-ion battery according to claim 1, characterized in that, The carbonization conditions for step 3) are: carbonization temperature of 500℃ and carbonization time of 2h.

6. CuP2@NC nanoparticles prepared by the method for preparing CuP2@NC using copper foil from a retired lithium-ion battery anode as described in claim 1.

7. The CuP2@NC nanoparticles as described in claim 6 are used as a negative electrode in sodium-ion batteries.

8. The application according to claim 7, characterized in that, The sodium-ion battery using CuP2@NC nanoparticles as the negative electrode achieved an initial coulombic efficiency of 88.7%.

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