CN114420921B - Method for regenerating lithium ion battery anode material by microwave - Google Patents

Method for regenerating lithium ion battery anode material by microwave Download PDF

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CN114420921B
CN114420921B CN202210321029.4A CN202210321029A CN114420921B CN 114420921 B CN114420921 B CN 114420921B CN 202210321029 A CN202210321029 A CN 202210321029A CN 114420921 B CN114420921 B CN 114420921B
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lithium
ion battery
lithium ion
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positive electrode
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CN114420921A (en
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徐佳丽
彭祖铃
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China Lithium Battery Technology Co Ltd
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China Lithium Battery Technology Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/54—Reclaiming serviceable parts of waste accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies
    • Y02W30/84—Recycling of batteries or fuel cells

Abstract

Discloses a method for regenerating a lithium ion battery cathode material by microwave, which comprises the following steps: (1) collecting the positive pole piece of the lithium ion battery and separating out a current collector to obtain a positive pole material of the lithium ion battery; (2) and (2) fully mixing the lithium ion battery positive electrode material obtained in the step (1) with a solid lithium source according to the amount of lithium matched Li/TM (lithium/metal) of 1-1.1, and then carrying out microwave treatment on the mixture in an air or pure oxygen atmosphere, wherein in the formula Li/TM, Li is the mole number of Li in the solid lithium source, and TM is the sum of the mole numbers of each metal element in the lithium ion battery positive electrode material obtained in the step (1). Through microwave treatment, energy consumption can be reduced, lithium supplement of the positive electrode material is realized, the supplemented lithium can reach the inside of the positive electrode material deeply, higher capacity recovery is realized, and the structure of the positive electrode material is recovered.

Description

Method for regenerating lithium ion battery anode material by microwave
Technical Field
The invention relates to the field of lithium ion batteries, in particular to a method for regenerating a lithium ion battery anode material by using microwaves.
Background
With the continuous development of new energy industry and the wide application of lithium ion batteries, the number of retired batteries will also increase explosively. In order to reduce the cost of comprehensively recycling the anode and cathode materials of the lithium ion battery and achieve the purposes of resource recycling and environmental protection, research on the recycling, regeneration and the like of the anode and cathode materials is becoming more and more urgent and important.
In the case of a positive electrode material for a lithium ion battery, after a long-term charge-discharge cycle, part of lithium remains in a negative electrode and cannot be deintercalated, so that the positive electrode material is deficient in lithium, and the battery capacity is significantly reduced. Therefore, the lithium supplement and structural repair of the positive electrode material have been continuously sought so that the positive electrode material can be regenerated and reused. In general, the direct regeneration method recovers the positive electrode material through a physical separation process, and then performs lithium supplement and structural defect repair through post-treatment processes (such as remelting and annealing) to obtain a regenerated positive electrode. The conventional direct regeneration method of the lithium ion battery is mostly limited to a high-temperature solid phase method, the method needs to be carried out at a higher temperature, the energy loss is large, and structural reduction cannot be realized at a high temperature for some recycled anode materials with serious structural damage, so that structural defects of the anode materials cannot be completely recovered.
Therefore, there is still a need for a new method for regenerating a lithium ion cathode material, which can save energy consumption, and can allow lithium atoms to reach the inner layer from the surface layer of the recovered cathode material to realize deep lithium supplement and structure repair of the cathode material simultaneously, compared with the existing high-temperature solid phase method.
Disclosure of Invention
In order to solve the above problems, the present inventors have conducted extensive studies and extensive experiments, and have proposed a novel method for regenerating a positive electrode material for a lithium ion battery by microwaves, in which the recovered positive electrode material is mixed with a lithium source, and subjected to microwave treatment in a solid phase state without the need for conventional high-temperature calcination.
Specifically, the invention provides a method for regenerating a lithium ion battery anode material by microwave, which comprises the following steps:
(1) collecting the positive pole piece of the lithium ion battery and separating out a current collector to obtain a positive pole material of the lithium ion battery;
(2) and (2) fully mixing the lithium ion battery positive electrode material obtained in the step (1) with a solid lithium source according to the amount of lithium matched Li/TM which is 1-1.1, drying, and then carrying out microwave treatment on the mixture in an air or pure oxygen atmosphere, wherein Li is the mole number of Li in the solid lithium source, and TM is the sum of the mole numbers of all metal elements in the lithium ion battery positive electrode material obtained in the step (1).
According to the method, when solid-phase microwave lithium supplement is carried out in the step (2), compared with the existing high-temperature solid-phase method, the microwave can promote lithium to jump from a ground state to an excited state, the excited lithium can be rapidly diffused to the surface of the ternary lithium ion battery anode material and a lattice structure with lithium vacancies inside, so that the effect of inhibiting lithium-nickel mixed discharge is achieved while the original layered structure is recovered, the surface lithium supplement of the anode material is realized, the internal structure of NCM is repaired, the method is also suitable for the ternary anode material with serious lattice collapse, and the effective recovery of deep performance can be realized; on the other hand, the microwave also has a high-frequency thermal effect and can supply heat for a lithium supplement system, so that the conventional high-temperature solid-phase method thermal reduction lithium supplement effect can be realized only by the microwave without external heating. In addition, the microwave lithium supplement technology can realize the direct regeneration of the NCM ternary cathode material in a short time, has short flow and simple and convenient operation, and is suitable for industrial production.
In short, through microwave treatment, not only can energy consumption be reduced and lithium supplement of the cathode material be realized, but also the supplemented lithium can reach the inside of the cathode material, higher capacity recovery is realized, and meanwhile, the structure of the cathode material is recovered.
Detailed Description
The present application will be described in further detail below with reference to examples. The features and advantages of the present application will become more apparent from the description.
In addition, the technical features related to the different embodiments of the present application described below may be combined with each other as long as they do not conflict with each other.
As mentioned above, the present invention provides a method for regenerating a lithium ion battery cathode material by microwave, comprising the following steps:
(1) collecting the positive pole piece of the lithium ion battery and separating out a current collector to obtain a positive pole material of the lithium ion battery;
(2) and (2) fully mixing the lithium ion battery positive electrode material obtained in the step (1) with a solid lithium source according to the amount of lithium matched Li/TM which is 1-1.1, drying, and then carrying out microwave treatment on the mixture in an air or pure oxygen atmosphere, wherein Li is the mole number of Li in the solid lithium source, and TM is the sum of the mole numbers of all metal elements in the lithium ion battery positive electrode material obtained in the step (1).
In one embodiment of the method according to the present invention, the method further comprises a step of performing alkaline washing on the lithium ion battery positive electrode material after step (1) and before step (2) to remove residual current collectors in the lithium ion battery positive electrode material.
In another embodiment of the method according to the invention, further comprising the step of performing an alcohol wash after the alkaline wash to remove residual alkali during the alkaline wash.
In another embodiment of the method according to the invention, the lithium ion battery positive electrode material is one or more selected from the group consisting of: LiMnO2；LiCoO2；LiNiO2；LiMn2O4；LiFePO4；LiNixCoyMn1-x-yO2Wherein x is more than 0 and less than 1, y is more than 0 and less than 1, and x + y is more than 0 and less than 1.
Preferably, the positive electrode material of the lithium ion battery is nickel-containingPositive electrode materials, e.g. LiNiO2Or LiNixCoyMn1-x- yO2Since Li generates lithium hydroxide in the aqueous phase, lithium vacancies are created in the structure; for nickel-containing materials, the presence of lithium vacancies can produce lithium-nickel mischarge. Therefore, lithium cannot be replenished particularly by water for a material containing nickel.
In another embodiment of the method according to the invention, the solid lithium source is lithium hydroxide (LiOH) or lithium carbonate (Li)2CO3)。
In another embodiment of the process according to the invention, the moisture content in the mixture described in step (2) is below 1000ppm, preferably below 500ppm, more preferably below 100 ppm.
In another embodiment of the method according to the invention, the frequency of the microwaves is between 17 and 300 GHz. When the microwave frequency is lower than 17GHz, the microwave penetration capability is weak, and lithium can be supplemented only by utilizing long-time microwave irradiation to generate high temperature, and lithium can be supplemented only on the surface of the material; when the frequency is more than 17GHz, lithium ions in the lithium source instantly obtain energy and jump from a ground state to an excited state, the microwave frequency is in a higher state, the penetration capability is strong, the lithium ions are promoted to be rapidly supplemented to lithium vacancies lacking in a material structure, and deep lithium supplement is realized.
In another embodiment of the method according to the present invention, the power of the microwave is 200 to 700W.
In another embodiment of the process according to the invention, the microwave treatment in step (2) is carried out for 0.5 to 5 hours.
In the invention, the positive pole piece of the lithium ion battery is collected and the current collector is separated, high-temperature desorption can be adopted, namely, the binder is melted by heating, and then the current collector is separated from the positive pole material by a tool such as a brush; or crushing the positive pole piece, and then dissolving the binder by a polar solvent to separate the current collector from the positive pole material.
Alternatively, when the current collector and the positive electrode material are separated by a solvent method, the crushed positive electrode fragments may be subjected to ultrasonic treatment in a polar solvent, followed by filtering the current collector with a screen, wherein the polar solvent is an aprotic polar solvent, for example, N-methylpyrrolidone (NMP), Dimethylsulfoxide (DMSO), N-Dimethylformamide (DMF), N-dimethylacetamide (DMAc), acetone, or the like; the ultrasonic treatment can be carried out at the temperature of 20-50 ℃ for 5-60 min, and the mesh size of the used screen can be generally 70-400 meshes, preferably 100-200 meshes according to the size of the positive fragments.
It is noted that after filtering the current collector through a screen, the polar solvent may be removed by a filtration (e.g., ceramic plate filtration) method, thereby obtaining a positive electrode material of a lithium ion battery from which the current collector is removed. If necessary, the cathode material can be dried and then used for the next step of microwave lithium supplement.
Alternatively, when the current collector and the positive electrode material are separated by a solvent method, a belt dryer can be used to dry the wet positive electrode material, the whole drying process is carried out in a closed drying box, and hot air is provided by a hot blast stove burning coal. And the anode filter cake is uniformly fed onto a conveyor belt in the drying box by a feeding machine, the conveyor belt moves forwards at a constant speed, and the product is output from the tail part of the drying box after being dried.
After drying, the obtained impurity-removed lithium ion battery anode material can be analyzed and tested by adopting a gradient temperature rise method of a Karl Fischer moisture tester, and the water content in the battery anode material is ensured to be less than or equal to 1000 ppm.
The specific test method comprises the following steps: heating and baking the test sample in a card type heating furnace by adopting a step-type heating method, and loading substances volatilized by baking the sample into a Karl Fischer test system by using high-purity nitrogen as carrier gas for testing. When the testing speed is reduced to the background speed +0.1 mug/s under each temperature gradient or the testing time reaches 20min, the test is stopped, and then the next temperature stage is entered for testing. The test temperature was 170 ℃ and the temperature gradient was 20 ℃.
As a preferred example of the lithium ion battery cathode material, the nickel-rich ternary cathode material has the advantages of high capacity, long service life, low cost, rich raw material sources and the like, and is a novel lithium ion battery material with a great application prospect. The nickel-rich ternary cathode material is initially in a layered structure, lithium can be reversibly inserted and extracted between layers, but after long-term charge-discharge cycle use, part of lithium remains in a cathode and cannot be extracted, lithium vacancies are generated in the layered structure due to lithium deficiency of the cathode material, and the lithium vacancies can cause collapse of the layered lattice structure and mixed discharge of lithium and nickel. Therefore, in addition to the lithium source for lithium supplement, it is important to sufficiently incorporate lithium into the interior thereof for effective repair of the layered structure thereof. According to the method, the microwave lithium supplement is completely carried out under a solid phase, so that the lithium source is prevented from reacting with water under a water phase system to generate lithium hydroxide, and further lithium vacancy is avoided.
Alternatively, the foregoing high-temperature thermal melting desorption or polar solvent desorption may cause a small amount of aluminum of the positive electrode current collector to remain in the positive electrode material separated from the current collector, so that preferably, before lithium supplement, the positive electrode material is treated by three-stage alkaline washing or excessive alkaline washing to remove the remaining aluminum of the current collector, where the three-stage alkaline washing refers to washing with three types of high, medium and low concentrations of alkali in sequence. The alkaline washing can adopt sodium hydroxide or lithium hydroxide solution, and in the case of adopting aluminum foil as a current collector, not only can residual aluminum scraps in the cathode material be removed, but also Al of a coating layer on the surface of the cathode material can be removed2O3And obstacles are eliminated for subsequent microwave lithium supplement, so that lithium can reach the interior of the positive electrode material structure. Three-stage alkali washing is carried out because of the surface coating layer Al2O3Firstly, sodium metaaluminate is generated with sodium hydroxide, then Al and water generate Al (OH)3Precipitating, and then generating sodium metaaluminate with the rest sodium hydroxide, wherein the sodium metaaluminate is easy to dissolve in water and the aluminum hydroxide is insoluble, and excessive alkali washing is adopted to prevent the aluminum hydroxide residue in the middle section, and the reaction formula is as follows:
Al2O3 + 2NaOH = 2NaAlO2 + H2o formula 1
2Al + 6H2O = 2Al(OH)3↓ + 3H2↓2
Al(OH)3 + NaOH = NaAlO2 + 2H2O formula 3
Further, when the solid-phase microwave lithium supplement is carried out according to the method of the invention, the lithium is supplemented with a high-temperature solid phaseCompared with the method, the microwave can not only generate a heat effect, but also promote lithium ions to transit from a ground state to an excited state, and excited lithium can be rapidly supplemented into a lattice structure with lithium vacancies inside, so that the anode material with lattice collapse recovers an initial layered structure. In addition, lithium cobaltate LiCoO is used as a binary positive electrode material with a layered structure2The method of the present invention is also applicable to the regeneration of the positive electrode material.
In the method according to the present invention, the positive electrode material obtained by alkali washing may be subjected to alcohol washing to prevent sodium hydroxide or lithium hydroxide from remaining, and the alcohol used for the aforementioned alcohol washing may be, for example, absolute ethyl alcohol, which is not particularly limited.
In the method, a solid lithium source is added according to the amount of lithium matched Li/TM which is 1-1.1 and mixed into a mixture, wherein Li is the mole number of Li in the solid lithium source, and TM is the sum of the mole numbers of metal elements in the lithium ion battery anode material subjected to ultrasonic treatment or ultrasonic and alkali washing treatment. When Li/TM is lower than 1, the stoichiometric ratio of lithium is less than 1, and the material is still in a lithium loss state; when Li/TM is greater than 1.1, the addition of an excessive amount of lithium source results in residual alkali (residual LiOH or LiCO) on the surface of the material3) And further affects the capacity recovery of the positive electrode material.
In the method, the microwave frequency used for the microwave solid phase lithium supplement is 17GHz-300 GHz. On one hand, the high-frequency thermal effect of the microwave can supply heat for the lithium supplement system, so that the lithium supplement effect of the conventional high-temperature solid phase method thermal reduction can be realized only by the microwave even if external heating is not needed, and the energy consumption can be greatly reduced by adopting the method disclosed by the invention. On the other hand, the microwave can promote lithium to transition from a ground state to an excited state, and the excited lithium can be rapidly diffused to a lithium position on the surface of the cathode material and collapsed in the internal structure, so that the original layered structure is restored, and the effect of inhibiting lithium-nickel mixed discharge is achieved. Therefore, according to the method provided by the invention, lithium can be supplemented to the surface layer of the cathode material, the internal structure of the cathode material can be repaired, and deep and sufficient lithium supplement and repair can be realized.
In the method, the power of the microwave solid phase lithium supplement is preferably 200-700W, and the time of the microwave solid phase lithium supplement is preferably 0.5-5 h. When the microwave power is lower than 200W, the heat generation effect is slow, and the lithium supplement efficiency is reduced; and the microwave power is higher than 700W, the heat runaway of the anode material is easy to occur, and the grain boundary fusion of the material is caused. In addition, when the microwave processing time is less than 0.5h, lithium in the lithium source is not completely excited, so that insufficient lithium supplement is caused, and the structure of the positive electrode material cannot be completely recovered; after the microwave treatment exceeds 5 hours, lithium supplement and structure repair of the material are realized, and unnecessary resource waste is caused by continuing the microwave treatment.
The present invention is further illustrated by the following examples.
Example 1
Mixing LiNi0.56Co0.12Mn0.32O2The method comprises the following steps of (N562) crushing a ternary positive plate, sending the crushed ternary positive plate into an NMP ultrasonic pool, carrying out ultrasonic treatment at 50 ℃ for 20min, filtering out a current collector aluminum foil by using a 300-mesh screen, pouring an ultrasonic pool solution into a ceramic filter plate filter, and collecting black powder of the positive electrode obtained by filtering. And (5) washing with absolute ethyl alcohol and drying to obtain the purified and impurity-removed recycled ternary cathode material.
And (3) uniformly mixing the purified and impurity-removed ternary cathode material with a LiOH lithium source, adjusting Li/TM to be 1.02, and directly performing microwave lithium supplement under the condition of pure oxygen, wherein the microwave frequency is 28GHz, and the microwave treatment time is 2 h.
Example 2
Reacting LiNi0.56Co0.12Mn0.32O2The method comprises the following steps of (N562) crushing a ternary positive plate, sending the crushed ternary positive plate into an NMP ultrasonic pool, carrying out ultrasonic treatment at 50 ℃ for 20min, filtering out a current collector aluminum foil by using a 300-mesh screen, pouring an ultrasonic pool solution into a ceramic filter plate filter, and collecting black powder of the positive electrode obtained by filtering. And sequentially adopting NaOH alkali liquids with high concentration (3mol/L), medium concentration (1mol/L) and low concentration (0.2mol/L) to wash and filter in sections to obtain ternary anode black powder, and finally washing and drying the ternary anode black powder by using absolute ethyl alcohol to obtain the purified and impurity-removed recovered ternary anode material.
And (3) uniformly mixing the purified and impurity-removed ternary cathode material with a LiOH lithium source, adjusting Li/TM to be 1.02, and directly performing microwave lithium supplement under the condition of pure oxygen, wherein the microwave frequency is 28GHz, and the microwave treatment time is 2 h.
Example 3
Reacting LiNi0.56Co0.12Mn0.32O2And (N562) crushing the ternary positive plate, putting the crushed ternary positive plate into a high-temperature box type furnace, carrying out heat treatment for 5 hours at 500 ℃, and carrying out vibration screening to obtain positive black powder. Sequentially washing the ternary anode black powder with three alkali liquids with high concentration (1mol/L) and low concentration (0.2mol/L) in a high concentration (3mol/L) manner to obtain a ternary anode material by stages, and finally washing and drying with absolute ethyl alcohol to obtain the purified ternary anode material.
Uniformly mixing the purified ternary cathode material with LiOH, adjusting Li/TM to 1.02, directly supplementing lithium by microwave under the condition of oxygen content, controlling the microwave frequency to be 28GHZ, and controlling the microwave treatment time to be 2 h.
Example 4
The process steps of example 1 were followed to perform microwave lithium replenishment, except that Li was used2CO3As a lithium source, the microwave frequency was 28 GHz.
Example 5
Microwave lithium replenishment was carried out according to the procedure of example 1, except that a lithium source was added to adjust the Li/TM to 1.10.
Example 6
The lithium was replenished by microwave according to the procedure of example 1, except that the microwave frequency was 17.6GHz and the microwave treatment time was 1 h.
Example 7
The process steps of example 1 were followed to supplement lithium with microwaves except that the microwave frequency was 300MHz and the microwave treatment time was 8 h.
Comparative example 1
Crushing the ternary positive plate, then sending the crushed ternary positive plate into a box type furnace, carrying out heat treatment at 500 ℃ for 5 hours, pouring the heat-treated plate material into a vibrating screen, screening current collector fragments and pole powder, carrying out sectional flushing and filtering on the collected pole powder by adopting NaOH alkali liquor with high (3mol/L), medium (1mol/L) and low (0.2mol/L) concentrations to obtain ternary positive black powder, finally washing by using absolute ethyl alcohol and drying to obtain the purified and impurity-removed recovered ternary positive material.
Adding LiOH lithium source, adjusting Li/TM to 1.02, introducing oxygen, and treating at 900 deg.C for 12 h.
Comparative example 2
And (3) crushing the ternary positive plate, then sending the crushed ternary positive plate into an NMP ultrasonic pool, carrying out ultrasonic treatment at 50 ℃ for 20min, then filtering out a current collector aluminum foil by using a screen, then pouring the ultrasonic pool solution into a ceramic filter plate filter, and collecting the filtered positive black powder. And sequentially adopting NaOH alkali liquids with high concentration (3mol/L), medium concentration (1mol/L) and low concentration (0.2mol/L) to wash and filter in sections to obtain ternary anode black powder, and finally washing and drying the ternary anode black powder by using absolute ethyl alcohol to obtain the purified and impurity-removed recovered ternary anode material. And then dispersing the ternary cathode material in a water phase, adding LiOH serving as a lithium source, adjusting the Li/TM to be 1.02, and treating for 2 hours under the microwave with the frequency of 28 GHz.
Comparative example 3
And (3) crushing the ternary positive plate, then sending the crushed ternary positive plate into an NMP ultrasonic pool, carrying out ultrasonic treatment at 50 ℃ for 20min, then filtering out a current collector aluminum foil by using a screen, then pouring the ultrasonic pool solution into a ceramic filter plate filter, and collecting the filtered positive black powder. And sequentially adopting NaOH alkali liquids with high concentration (3mol/L), medium concentration (1mol/L) and low concentration (0.2mol/L) to wash and filter in sections to obtain ternary anode black powder, and finally washing and drying the ternary anode black powder by using absolute ethyl alcohol to obtain the purified and impurity-removed recovered ternary anode material. Then, the lithium is supplemented by microwave under the condition of pure oxygen, the microwave frequency is 50MHz, and the microwave treatment time is 2 h.
Comparative example 4
And (3) crushing the ternary positive plate, then sending the crushed ternary positive plate into an NMP ultrasonic pool, carrying out ultrasonic treatment at 50 ℃ for 20min, then filtering out a current collector aluminum foil by using a screen, then pouring the ultrasonic pool solution into a ceramic filter plate filter, and collecting the filtered positive black powder. And sequentially adopting NaOH alkali liquids with high concentration (3mol/L), medium concentration (1mol/L) and low concentration (0.2mol/L) to wash and filter in sections to obtain ternary anode black powder, and finally washing and drying the ternary anode black powder by using absolute ethyl alcohol to obtain the purified and impurity-removed recovered ternary anode material. Then, the lithium is supplemented by microwave under the condition of pure oxygen, the microwave frequency is 500GHz, and the microwave treatment time is 2 h.
The performance test of the battery is explained next.
And (3) testing the cycle performance: the regenerated positive electrode materials from examples and comparative examples were subjected to positive electrode slurry mixing of 97.6% positive electrode material +0.9% conductive carbon SP +1.1% PVDF +0.4CNTs in NMP at 25 ℃, double-coated, and assembled into a monolithic battery. The full charge-discharge cycle test was performed until the capacity of the battery was reduced to 80% of the initial capacity by charging at the maximum charge rate and discharging at 1C rate, and the capacity retention rate was recorded, and the test results and the details of each example and comparative example are summarized in table 1 below.
It is to be noted that the sources of the materials used in the present invention are as follows:
name of material For short Source
Conductive carbon SP cabot
PVDF (polyvinylidene fluoride) Suwei
Carbon nanotube CNTs tiannai
NaOH sodium hydroxide
N-methylpyrrolidone NMP rhizoma
TABLE 1
Figure DEST_PATH_IMAGE001
As shown in Table 1 above, the discharge capacity retention rates of examples 1 to 7 were all 95% or more; comparing examples 1-2 and comparative example 1, the regenerated active material obtained by microwave lithium supplement showed better cycle stability after being assembled into a battery, mainly because: a microwave lithium supplement mode is not adopted, Li which is lacked in the ternary cathode material cannot be supplemented, and therefore the capacity recovery rate is low; compared with the examples 1-2 and the comparative example 2, the regenerated active material obtained by microwave hydrothermal lithium supplement shows poor cycle performance after being assembled into a battery, mainly because the microwave hydrothermal lithium supplement has water participation, water is used as a transmission medium and can absorb the energy of microwave to generate heat, under the condition of existence of the water, excited lithium ions can contact water molecules and are rapidly quenched by the energy absorbed by the water molecules, and lithium supplement can not be realized through transition of the lithium ions, so that the capacity retention rate is far lower than that of the microwave solid-phase lithium supplement disclosed by the invention; with the combination of examples 1-7 and comparative examples 3 and 4, the cycle performance is reduced when the microwave frequency is lower than 17 GHz/higher than 300 GHz.
Therefore, the lithium ion battery anode material regenerated by alkali washing and solid-phase microwave lithium supplement according to the method has better cycle performance, short flow and low energy consumption, and is more beneficial to industrial production.
The present application has been described above in connection with preferred embodiments, which are, however, merely exemplary and illustrative. On the basis of the above, the present application can be subjected to various substitutions and modifications, and the present application is in the protection scope of the present application.

Claims (9)

1. A method for regenerating a lithium ion battery anode material by microwave is characterized by comprising the following steps:
(1) collecting the positive pole piece of the lithium ion battery and separating out a current collector to obtain a positive pole material of the lithium ion battery;
(2) fully mixing the lithium ion battery positive electrode material obtained in the step (1) with a solid lithium source according to the amount of lithium Li/TM which is 1.02-1.1, and then carrying out microwave treatment on the mixture in the atmosphere of air or pure oxygen, wherein in the formula Li/TM, Li is the mole number of Li in the solid lithium source, and TM is the sum of the mole numbers of all metal elements in the lithium ion battery positive electrode material obtained in the step (1);
the moisture content of the mixture in step (2) is less than 1000 ppm.
2. The method according to claim 1, further comprising a step of performing alkali washing on the lithium ion battery positive electrode material after the step (1) and before the step (2) to remove residual current collectors in the lithium ion battery positive electrode material.
3. The method of claim 2, further comprising the step of performing an alcohol wash after the alkaline wash to remove residual alkali from the alkaline wash.
4. The method according to any one of claims 1 to 3, wherein the lithium ion battery positive electrode material is one or more selected from the group consisting of: LiMnO2；LiCoO2；LiNiO2；LiMn2O4；LiFePO4；LiNixCoyMn1-x-yO2Wherein x is more than 0 and less than 1, y is more than 0 and less than 1, and x + y is more than 0 and less than 1.
5. The method of claim 4, wherein the lithium ion battery positive electrode material is LiNiO2(ii) a Or is LiNixCoyMn1-x-yO2Wherein x is more than 0 and less than 1, y is more than 0 and less than 1, and x + y is more than 0 and less than 1.
6. The method of claim 4, wherein the solid lithium source is LiOH or Li2CO3。
7. The method according to claim 1, wherein the frequency of the microwave is 17 to 300 GHz.
8. The method according to claim 7, wherein the power of the microwave is 200-700W.
9. The method according to claim 1, wherein the microwave treatment in the step (2) is performed for 0.5 to 5 hours.
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