Alkali metal ion battery positive electrode material repair and regeneration method, positive electrode material and application

Abstract

The present invention discloses a method for repairing and regenerating positive electrode materials of alkali metal ion batteries, positive electrode materials and applications thereof, wherein the repair and regeneration method comprises: pretreatment, doping the recovered positive electrode materials with halide ions, and / or doping the Ni in the positive electrode materials with alkyl free radicals. 3+ Reduction; Alkali metal supplementation, adding alkali metal ions to the pretreated positive electrode material; Sintering, sintering the positive electrode material after supplementation of alkali metal ions. This application uses halide ions to dope the recovered positive electrode material. The addition of halide ions can attract alkali metal ions, reduce the migration energy of alkali metals, and stabilize the material skeleton; Alkane free radicals have reducing properties and can reduce Ni 3+ Reduction to Ni 2+ According to the principle of charge conservation, the diffusion resistance of alkali metal ions can be reduced. Both can make the waste positive electrode powder have a better alkali metal replenishing effect in the alkali metal replenishing process.

Description

Technical Field

[0001] The present invention relates to the technical field of alkali metal ion batteries, and in particular to a method for repairing and regenerating positive electrode materials of alkali metal ion batteries, positive electrode materials and applications thereof. Background Art

[0002] Alkali metal ion batteries include lithium ion batteries, sodium ion batteries and potassium ion batteries. Among them, lithium ion batteries are currently widely used, while sodium ion batteries and potassium ion batteries are less used and are mainly in the research stage.

[0003] Lithium nickel cobalt manganese oxide (LNCMnO) offers advantages such as low pollution, low cost, high performance, and excellent stability. As one of the most widely used cathode materials for lithium-ion batteries, it holds excellent development prospects. The increasing use of ternary batteries has generated a large amount of waste batteries, which contain a large number of valuable components with great recycling value and significance. Faced with such a huge recycling market, the development of efficient and low-cost recycling technologies is urgently needed to avoid wasting resources.

[0004] The traditional process is generally to recycle valuable metal elements, prepare them into valuable metal salts, and then prepare positive electrode materials. For example, CN110724818A discloses a fully wet recycling process for waste lithium batteries, which has the advantages of a short process and a high recovery rate. However, the traditional wet process involves acid dissolution and chemical precipitation, and a large amount of acid solution is used, which complicates the recycling process. In addition, there are some regeneration methods that regenerate and repair positive electrode materials by directly supplementing lithium elements. For example, CN111410239A discloses a regeneration and recovery method for retired nickel cobalt manganese oxide battery positive electrode materials, which uses direct lithium supplementation and calcination to regenerate positive electrode materials, and has the advantages of simple operation, low cost, and high recovery rate. However, Ni in waste positive electrode materials 3+ The presence of Li + The strong repulsive force of ions makes Li + It is difficult to replenish the ions into the defective sites of the used positive electrode materials, resulting in lithium replenishment efficiency that cannot meet expectations.

[0005] Based on the current development of lithium-ion batteries, we can speculate that sodium-ion batteries and potassium-ion batteries may also face similar situations as lithium-ion batteries. Therefore, it is very necessary to develop a method for repairing and regenerating the positive electrode of spent alkali metal ion batteries with high alkali metal replenishment efficiency.

[0006] In view of this, the present invention is proposed. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for repairing and regenerating an alkali metal ion battery cathode material, a cathode material and an application thereof.

[0008] The present invention is achieved in that:

[0009] In a first aspect, the present invention provides a method for repairing and regenerating a cathode material of an alkali metal ion battery, comprising the following steps:

[0010] Pretreatment, using halide ions to dope the recovered cathode material, and / or using alkyl radicals to dope the Ni in the cathode material 3+ Perform restoration;

[0011] Alkali metal supplementation: analyzing the content of each element in the recovered positive electrode material, and supplementing the doped positive electrode material with alkali metal ions according to the element stoichiometric ratio of the positive electrode material;

[0012] Sintering: Sintering the positive electrode material after the alkali metal ions are supplemented to obtain a repaired positive electrode material.

[0013] In an optional embodiment, the pretreatment is to perform plasma irradiation on the positive electrode material using a plasma generator;

[0014] Preferably, the gas source of the plasma generating device is a halide;

[0015] Preferably, the halogen in the alkyl halide is fluorine;

[0016] Preferably, the alkyl halide is at least one of monofluoroethane, monofluoromethane or 1-fluoropropane.

[0017] Preferably, the fluorine doping amount is 0.5%-5% of the mass fraction of the recovered positive electrode material.

[0018] In an optional embodiment, the power of the plasma generating device is 50-200 W, and the plasma irradiation time is 5-60 min.

[0019] In an optional embodiment, the positive electrode material contains alkali metal and nickel;

[0020] Preferably, the positive electrode material is a lithium-ion battery positive electrode material;

[0021] Preferably, the positive electrode material is NCM positive electrode material.

[0022] In an optional embodiment, the positive electrode material is in powder form.

[0023] In an optional embodiment, the supplementation of alkali metal ions is performed by mixing the pretreated positive electrode material with an alkali metal source;

[0024] Preferably, the mixing is performed by grinding;

[0025] Preferably, the alkali metal source is one or more of alkali metal hydroxides, alkali metal carbonates, alkali metal sulfates, alkali metal nitrates, alkali metal chlorides, alkali metal oxalates, and alkali metal acetates;

[0026] Preferably, the alkali metal is lithium.

[0027] In an optional embodiment, the sintering temperature is 800-1000° C., and the sintering time is 2-10 h;

[0028] Preferably, the sintering is performed in an oxygen atmosphere.

[0029] In an optional embodiment, the positive electrode material is obtained by pyrolyzing a positive electrode sheet.

[0030] In a second aspect, the present invention provides a positive electrode material obtained by the method for repairing and regenerating positive electrode materials for alkali metal ion batteries according to any one of the aforementioned embodiments.

[0031] In a third aspect, the present invention provides a use of the positive electrode material described in any one of the aforementioned embodiments in an alkali metal ion battery.

[0032] The present invention has the following beneficial effects:

[0033] The present invention adopts halide ions to dope the recovered positive electrode material. The incorporation of halide ions can attract alkali metal ions, reduce the migration energy of alkali metals, and stabilize the material skeleton. Alkane free radicals have reducing properties and can convert Ni 3+ Reduction to Ni 2+ According to the principle of charge conservation, the diffusion resistance of alkali metal ions can be reduced. Both can make the waste positive electrode material have a better alkali metal replenishing effect in the alkali metal replenishing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 This is a flow chart of the repair and regeneration of the positive electrode material of the alkali metal ion battery in this application. DETAILED DESCRIPTION

[0036] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0037] This embodiment provides a method for repairing and regenerating positive electrode materials of alkali metal ion batteries, such as Figure 1 As shown, the following steps are included:

[0038] Pretreatment, using halide ions to dope the recovered cathode material, and / or using alkyl radicals to dope the Ni in the cathode material 3+ Perform restoration;

[0039] Supplementing alkali metals, analyzing the content of each element, and supplementing alkali metal ions into the doped positive electrode material according to the element stoichiometric ratio of the recovered positive electrode material;

[0040] Sintering: Sintering the positive electrode material after the alkali metal ions are supplemented to obtain a repaired positive electrode material.

[0041] The present invention adopts halide ions to dope the recovered positive electrode material. The incorporation of halide ions can attract alkali metal ions, reduce the migration energy of alkali metals, and stabilize the material skeleton. Alkane free radicals have reducing properties and can convert Ni 3+ Reduction to Ni 2+ According to the principle of charge conservation, the diffusion resistance of alkali metal ions can be reduced. Both can make the waste positive electrode powder have a better alkali metal replenishing effect in the alkali metal replenishing process.

[0042] When halide ions are used to dope the positive electrode material, alkyl radicals are used to dope the Ni 3+ The two work together to make the waste cathode powder treated in this way have a better effect in the process of replenishing alkali metals than the single doping of halide ions or the single use of alkyl radicals to reduce the Ni in the cathode material. 3+ The reduction is carried out and the effect of replenishing alkali metals is more significantly improved.

[0043] While existing techniques involve fluorine doping during the synthesis of positive electrode materials, the present application addresses a different technical problem. Fluorine and other halide ions are doped to increase the efficiency and effectiveness of the alkali metal ion replenishment process. Furthermore, fluorine doping during the synthesis process displaces other anions (such as oxygen) rather than increasing the anion content, and thus fails to increase the anion ratio and regulate charge balance.

[0044] In another optional embodiment of the present application, the pretreatment is to perform plasma irradiation on the positive electrode material using a plasma generator;

[0045] Preferably, the gas source of the plasma generating device is a halide;

[0046] Preferably, the halogen in the alkyl halide is fluorine;

[0047] Preferably, the alkyl halide is at least one of monofluoroethane, monofluoromethane or 1-fluoropropane.

[0048] Preferably, the fluorine doping amount is 0.5%-5% of the mass fraction of the recovered positive electrode material.

[0049] The plasma in this embodiment can be generated by electrostatic coupling, inductive coupling, and electromagnetic wave coupling. Compared with the ordinary mixed doping method, plasma doping, on the one hand, does not cause the introduction of a large amount of carbon elements while doping fluorine ions, and does not reduce the initial discharge gram capacity of the material; on the other hand, alkyl radicals and halide ions can more fully interact with the positive electrode material, and the doping effect is better.

[0050] There are oxygen vacancies in the failed ternary positive electrode material. The electronegativity of fluorine is stronger than that of oxygen. After fluorine enters the oxygen vacancy, it is not easily captured. Fluorine entering the oxygen vacancy increases the content of negative ions. Since there are no vacancies in the positive electrode material that can accommodate alkyl free radicals, the alkyl free radicals reduce trivalent nickel to divalent nickel and are not doped in the positive electrode material. The two can work together to reduce the resistance to lithium entry during the lithium replenishment process.

[0051] Using halogenated hydrocarbons as doping raw materials, the plasma doping method adopted does not require the introduction of other impurities. The doping effect can be controlled by controlling the flow rate of the doping raw materials and the power of the plasma generator. The doping method is more environmentally friendly and controllable.

[0052] In other optional embodiments of the present application, the power of the plasma generating device is any value between 50-200 W, for example, 50 W, 100 W, 150 W, 200 W, etc. can be selected; the time of the plasma irradiation is any value between 5-60 min, for example, 5 min, 15 min, 30 min, 45 min, 60 min, etc. can be selected.

[0053] The optimal parameters of power, irradiation time and doping material flow rate can be adjusted according to the doping amount.

[0054] In other optional embodiments of the present application, the positive electrode material contains alkali metal and nickel;

[0055] Preferably, the positive electrode material is a lithium-ion battery positive electrode material;

[0056] Preferably, the positive electrode material is NCM positive electrode material.

[0057] In other optional embodiments of the present application, the positive electrode material is in powder form, and the particle size is related to the recycled positive electrode material. The powder form is beneficial to improving the uniformity of doping.

[0058] In other optional embodiments of the present application, the supplementation of alkali metal ions is performed by mixing the pretreated positive electrode material with an alkali metal source;

[0059] Preferably, the mixing is performed by grinding;

[0060] Preferably, the alkali metal source is one or more of alkali metal hydroxides, alkali metal carbonates, alkali metal sulfates, alkali metal nitrates, alkali metal chlorides, alkali metal oxalates, and alkali metal acetates;

[0061] Preferably, the alkali metal is lithium.

[0062] In other optional embodiments of the present application, the sintering temperature can be any value between 800-1000°C, for example, 800°C, 850°C, 900°C, 950°C, 100°C, etc., and the sintering time can be any value between 2-10h, for example, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, etc.;

[0063] Preferably, the sintering is performed in an oxygen atmosphere.

[0064] In other optional embodiments of the present application, the positive electrode material is obtained by pyrolysis of the positive electrode sheet. Pyrolysis only separates the positive electrode material in the positive electrode sheet. In order to improve the doping effect, the positive electrode material can be crushed after separation to make the positive electrode material into powder.

[0065] In a second aspect, the present invention provides a positive electrode material obtained by the method for repairing and regenerating positive electrode materials for alkali metal ion batteries according to any one of the aforementioned embodiments.

[0066] In a third aspect, the present invention provides a use of the positive electrode material described in any one of the aforementioned embodiments in an alkali metal ion battery.

[0067] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0068] Example 1:

[0069] This embodiment provides a method for repairing and regenerating a cathode material of an alkali metal ion battery, comprising the following steps:

[0070] Step 1: After discharging, disassemble and sort the used NCM523 batteries to obtain the positive electrode sheets.

[0071] Step 2: Pyrolysis the positive electrode sheet to peel off the positive electrode powder.

[0072] Step 3: Plasma doping of the spent cathode powder was performed. The plasma power was 100 W, the treatment time was 5 minutes, and the doping material was fluoroethane. According to elemental analysis, the fluorine doping level was 1% of the mass fraction of the spent cathode material. If the fluorine doping level indicated by elemental analysis was insufficient, the treatment was repeated until the fluorine doping level reached 1% of the mass fraction of the spent cathode material.

[0073] Step 4: Weigh the lithium source to be replenished based on the elemental ratio of the positive electrode material. Grind and mix the doped spent positive electrode powder and lithium carbonate.

[0074] Step 5: After grinding, the powder is sintered at 850°C for 4 hours in an oxygen atmosphere to obtain the repaired positive electrode material.

[0075] The capacity of the repaired cathode material was tested. The following method was used: the regenerated cathode material, acetylene black, and PVDF were homogenized in a mass ratio of 8:1:1. The slurry was then coated onto aluminum foil. After drying, the slurry was cut into pieces, weighed, roller-pressed, and vacuum-dried to obtain the cathode sheets. A lithium metal sheet was used as the anode, Celgard 2500 as the separator, the electrolyte was 1.0M LiPF6, and the electrolyte solvent was an EC:DMC (mass ratio of 3:7). CR2032 button cells were assembled in a glove box.

[0076] The test temperature was 25°C, the test cutoff voltage was 2.8-4.3V, and the test process was carried out at a charge and discharge rate of 1C (1C=150mAh / g). It was measured that the initial discharge capacity of the repaired and regenerated material could reach 151.5mAh / g. After 100 cycles, the discharge capacity was 141.2mAh / g, and the capacity retention rate was 93.2%.

[0077] Example 2:

[0078] This embodiment provides a method for repairing and regenerating a cathode material of an alkali metal ion battery, comprising the following steps:

[0079] Step 1: After discharging, disassemble and sort the used NCM523 batteries to obtain the positive electrode sheets.

[0080] Step 2: Pyrolysis the positive electrode sheet to peel off the positive electrode powder.

[0081] Step 3: Plasma doping of the spent cathode powder was performed. The plasma power was 100 W, the treatment time was 3 minutes, and the doping material was fluoromethane. Elemental analysis indicated that the fluorine doping level was 0.5% of the mass fraction of the spent cathode material. If the fluorine doping level indicated by elemental analysis was insufficient, the treatment was repeated until the fluorine doping level reached 0.5% of the mass fraction of the spent cathode material.

[0082] Step 4: Analyze the content of each element and grind and mix the doped waste positive electrode powder and lithium carbonate according to the element stoichiometric ratio of the positive electrode material.

[0083] Step 5: After grinding, the powder is sintered at 850°C for 4 hours in an oxygen atmosphere to obtain the repaired positive electrode material.

[0084] Under the same method and conditions as in Example 1, it was measured that the initial discharge capacity of the repaired and regenerated material could reach 151.8 mAh / g. After 100 cycles, the discharge capacity was 141 mAh / g, and the capacity retention rate was 92.9%.

[0085] Example 3:

[0086] This embodiment provides a method for repairing and regenerating a cathode material of an alkali metal ion battery, comprising the following steps:

[0087] Step 1: After discharging, disassemble and sort the used NCM523 batteries to obtain the positive electrode sheets.

[0088] Step 2: Pyrolysis the positive electrode sheet to peel off the positive electrode powder.

[0089] Step 3: Plasma doping of the spent cathode powder was performed. The plasma power was 100 W, the treatment time was 8 minutes, and the doping material was fluoromethane. According to elemental analysis, the fluorine doping level was 2% of the mass fraction of the spent cathode material. If the fluorine doping level indicated by elemental analysis was insufficient, the treatment was repeated until the fluorine doping level reached 2% of the mass fraction of the spent cathode material.

[0090] Step 4: Analyze the content of each element and grind and mix the doped waste positive electrode powder and lithium carbonate according to the element stoichiometric ratio of the positive electrode material.

[0091] Step 5: After grinding, the powder is sintered at 850°C for 4 hours in an oxygen atmosphere to obtain the repaired positive electrode material.

[0092] Under the same method and conditions as in Example 1, it was measured that the initial discharge capacity of the repaired and regenerated material could reach 150.9 mAh / g. After 100 cycles, the discharge capacity was 140.9 mAh / g, and the capacity retention rate was 93.4%.

[0093] Comparative Example 1:

[0094] This embodiment provides a method for repairing and regenerating a cathode material of an alkali metal ion battery, comprising the following steps:

[0095] Step 1: After discharging, disassemble and sort the used NCM523 batteries to obtain the positive electrode sheets.

[0096] Step 2: Pyrolysis the positive electrode sheet to peel off the positive electrode powder.

[0097] Step 3: Plasma doping of the spent cathode powder. The plasma power was 100 W, and the treatment time was 2 minutes. Fluorine gas was used as the doping source. Elemental analysis indicated that the fluorine doping level was 1% of the mass fraction of the spent cathode material. If the fluorine doping level indicated by elemental analysis was insufficient, the treatment was repeated until the fluorine doping level reached 1% of the mass fraction of the spent cathode material.

[0098] Step 4: Analyze the content of each element and grind and mix the doped waste positive electrode powder and lithium carbonate according to the element stoichiometric ratio of the positive electrode material.

[0099] Step 5: After grinding, the powder is sintered at 850°C for 4 hours in an oxygen atmosphere to obtain the repaired positive electrode material.

[0100] Under the same method and conditions as in Example 1, it was measured that the initial discharge capacity of the repaired and regenerated material could reach 142.3 mAh / g. After 100 cycles, the discharge capacity was 125.4 mAh / g, and the capacity retention rate was 88.1%.

[0101] Comparative Example 2:

[0102] This embodiment provides a method for repairing and regenerating a cathode material of an alkali metal ion battery, comprising the following steps:

[0103] Step 1: After discharging, disassemble and sort the used NCM523 batteries to obtain the positive electrode sheets.

[0104] Step 2: Pyrolysis the positive electrode sheet to peel off the positive electrode powder.

[0105] Step 3: Plasma doping of the waste cathode powder. Plasma power 100W, treatment time 5min, doping raw material methane.

[0106] Step 4: Analyze the content of each element and grind and mix the doped waste positive electrode powder and lithium carbonate according to the element stoichiometric ratio of the positive electrode material.

[0107] Step 5: After grinding, the powder is sintered at 850°C for 4 hours in an oxygen atmosphere to obtain the repaired positive electrode material.

[0108] Under the same method and conditions as in Example 1, it was measured that the initial discharge capacity of the repaired and regenerated material could reach 147.2 mAh / g. After 100 cycles, the discharge capacity was 119.4 mAh / g, and the capacity retention rate was 81.1%.

[0109] Comparative Example 3:

[0110] This comparative example provides a method for repairing and regenerating a positive electrode material of an alkali metal ion battery, comprising the following steps:

[0111] Step 1: After discharging, disassemble and sort the used NCM523 batteries to obtain the positive electrode sheets.

[0112] Step 2: Pyrolysis the positive electrode sheet to peel off the positive electrode powder.

[0113] Step 3: Analyze the content of each element and grind and mix the spent cathode powder with a lithium source based on the elemental stoichiometric ratio of the cathode material. The lithium source is lithium hydroxide.

[0114] Step 4: After grinding, the powder is sintered at 850°C for 4 hours in an oxygen atmosphere to obtain the repaired positive electrode material.

[0115] Under the same method and conditions as in Example 1, it was measured that the initial discharge capacity of the repaired and regenerated material could reach 140.3 mAh / g. After 100 cycles, the discharge capacity was 116.7 mAh / g, and the capacity retention rate was 83.2%.

[0116] Table 1 Effects of various embodiments and comparative examples

[0117]

[0118]

[0119] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for repairing and regenerating positive electrode materials of alkali metal ion batteries, characterized in that: The following steps are involved: Pretreatment, wherein the pretreatment uses halide ions to dope the recovered positive electrode material, and uses alkyl radicals to dope Ni in the positive electrode material. 3+ Reduction is performed; the pretreatment is to irradiate the cathode material with plasma using a plasma generator, the gas source of the plasma generator is a haloalkane, and the haloalkane is at least one of monofluoroethane, monofluoromethane or 1-fluoropropane; Supplementing alkali metals, replenishing alkali metal ions into the pretreated positive electrode material; Sintering: Sintering the positive electrode material after the alkali metal ions are supplemented to obtain a repaired positive electrode material.

2. The method for repairing and regenerating the positive electrode material of an alkali metal ion battery according to claim 1, characterized in that: The amount of fluorine doping in the pretreatment step is 0.5%-5% of the mass fraction of the recovered positive electrode material.

3. The method for repairing and regenerating the positive electrode material of an alkali metal ion battery according to claim 1, characterized in that: The power of the plasma generating device is 50-200W, and the plasma irradiation time is 5-60 minutes.

4. The method for repairing and regenerating the positive electrode material of an alkali metal ion battery according to claim 1, characterized in that: The positive electrode material is a lithium ion battery positive electrode material.

5. The method for repairing and regenerating the positive electrode material of an alkali metal ion battery according to claim 1, characterized in that: The positive electrode material is NCM positive electrode material.

6. The method for repairing and regenerating the positive electrode material of an alkali metal ion battery according to claim 1, characterized in that: The positive electrode material is in powder form.

7. The method for repairing and regenerating the positive electrode material of an alkali metal ion battery according to claim 1, characterized in that: The alkali metal ions are supplemented by mixing the pretreated positive electrode material with an alkali metal source.

8. The method for repairing and regenerating the positive electrode material of an alkali metal ion battery according to claim 7, characterized in that: The mixing is performed by grinding.

9. The method for repairing and regenerating the positive electrode material of an alkali metal ion battery according to claim 7, characterized in that: The alkali metal source is one or more of alkali metal hydroxides, alkali metal carbonates, alkali metal sulfates, alkali metal nitrates, alkali metal chlorides, alkali metal oxalates, and alkali metal acetates.

10. The method for repairing and regenerating the positive electrode material of an alkali metal ion battery according to claim 9, characterized in that: The alkali metal is lithium.

11. The method for repairing and regenerating the positive electrode material of an alkali metal ion battery according to claim 1, characterized in that: The sintering temperature is 800-1000° C., and the sintering time is 2-10 h.

12. The method for repairing and regenerating the positive electrode material of an alkali metal ion battery according to claim 11, characterized in that: The sintering is performed in an oxygen atmosphere.

13. The method for repairing and regenerating positive electrode materials of alkali metal ion batteries according to claim 1, characterized in that: The positive electrode material is obtained by pyrolyzing a positive electrode sheet.

14. A positive electrode material obtained by the method for repairing and regenerating positive electrode materials for alkali metal ion batteries according to any one of claims 1 to 13.

15. Use of the positive electrode material according to claim 14 in an alkali metal ion battery.

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