CN117003235A - Method for regenerating graphite in waste battery - Google Patents
Method for regenerating graphite in waste battery Download PDFInfo
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- CN117003235A CN117003235A CN202310703684.0A CN202310703684A CN117003235A CN 117003235 A CN117003235 A CN 117003235A CN 202310703684 A CN202310703684 A CN 202310703684A CN 117003235 A CN117003235 A CN 117003235A
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 191
- 229910002804 graphite Inorganic materials 0.000 title claims abstract description 177
- 239000010439 graphite Substances 0.000 title claims abstract description 177
- 238000000034 method Methods 0.000 title claims abstract description 42
- 239000010926 waste battery Substances 0.000 title claims abstract description 22
- 230000001172 regenerating effect Effects 0.000 title claims abstract description 12
- 238000000576 coating method Methods 0.000 claims abstract description 34
- 238000000498 ball milling Methods 0.000 claims abstract description 31
- 238000001354 calcination Methods 0.000 claims abstract description 31
- 239000011248 coating agent Substances 0.000 claims abstract description 31
- 239000002699 waste material Substances 0.000 claims abstract description 28
- 239000000463 material Substances 0.000 claims abstract description 25
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims abstract description 24
- 229910001416 lithium ion Inorganic materials 0.000 claims abstract description 24
- 239000010405 anode material Substances 0.000 claims abstract description 23
- 238000001035 drying Methods 0.000 claims abstract description 19
- 238000011065 in-situ storage Methods 0.000 claims abstract description 9
- 239000002904 solvent Substances 0.000 claims abstract description 8
- 239000012298 atmosphere Substances 0.000 claims abstract description 7
- 239000010406 cathode material Substances 0.000 claims abstract description 7
- 238000010907 mechanical stirring Methods 0.000 claims abstract description 7
- 239000007788 liquid Substances 0.000 claims abstract description 6
- 239000010426 asphalt Substances 0.000 claims description 36
- 239000002253 acid Substances 0.000 claims description 29
- 239000007773 negative electrode material Substances 0.000 claims description 26
- 238000003756 stirring Methods 0.000 claims description 22
- 239000012535 impurity Substances 0.000 claims description 18
- 229910003481 amorphous carbon Inorganic materials 0.000 claims description 17
- 230000008569 process Effects 0.000 claims description 17
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 16
- 229910052751 metal Inorganic materials 0.000 claims description 16
- 239000002184 metal Substances 0.000 claims description 16
- 238000001291 vacuum drying Methods 0.000 claims description 16
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims description 15
- 238000000746 purification Methods 0.000 claims description 15
- 238000011069 regeneration method Methods 0.000 claims description 15
- 238000010438 heat treatment Methods 0.000 claims description 14
- 239000002994 raw material Substances 0.000 claims description 14
- JUJWROOIHBZHMG-UHFFFAOYSA-N Pyridine Chemical compound C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 claims description 12
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 claims description 12
- 238000002791 soaking Methods 0.000 claims description 12
- 238000002386 leaching Methods 0.000 claims description 11
- 238000012216 screening Methods 0.000 claims description 10
- 239000011230 binding agent Substances 0.000 claims description 9
- 238000001816 cooling Methods 0.000 claims description 9
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 8
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 8
- 229910052799 carbon Inorganic materials 0.000 claims description 8
- 238000003837 high-temperature calcination Methods 0.000 claims description 8
- 229910021645 metal ion Inorganic materials 0.000 claims description 7
- 239000003960 organic solvent Substances 0.000 claims description 7
- 238000004140 cleaning Methods 0.000 claims description 6
- 239000008367 deionised water Substances 0.000 claims description 6
- 229910021641 deionized water Inorganic materials 0.000 claims description 6
- 238000001914 filtration Methods 0.000 claims description 6
- UMJSCPRVCHMLSP-UHFFFAOYSA-N pyridine Natural products COC1=CC=CN=C1 UMJSCPRVCHMLSP-UHFFFAOYSA-N 0.000 claims description 6
- 238000007790 scraping Methods 0.000 claims description 6
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 claims description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 claims description 5
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 claims description 5
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 claims description 4
- 229910052786 argon Inorganic materials 0.000 claims description 4
- 239000003792 electrolyte Substances 0.000 claims description 4
- 229910052757 nitrogen Inorganic materials 0.000 claims description 4
- -1 salt sulfate Chemical class 0.000 claims description 4
- 230000000630 rising effect Effects 0.000 claims description 3
- 238000001704 evaporation Methods 0.000 claims description 2
- 230000035484 reaction time Effects 0.000 claims description 2
- 238000005554 pickling Methods 0.000 claims 1
- 238000011084 recovery Methods 0.000 abstract description 16
- 238000003763 carbonization Methods 0.000 abstract description 7
- 239000002245 particle Substances 0.000 abstract description 6
- 238000004064 recycling Methods 0.000 abstract description 4
- 238000010306 acid treatment Methods 0.000 abstract 1
- 239000002002 slurry Substances 0.000 description 18
- 239000000047 product Substances 0.000 description 10
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 8
- 229910052744 lithium Inorganic materials 0.000 description 8
- 239000012299 nitrogen atmosphere Substances 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- 230000001276 controlling effect Effects 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 239000000203 mixture Substances 0.000 description 7
- 239000003921 oil Substances 0.000 description 7
- 230000008439 repair process Effects 0.000 description 6
- 238000000967 suction filtration Methods 0.000 description 6
- 230000007547 defect Effects 0.000 description 5
- 150000003839 salts Chemical class 0.000 description 5
- 238000000926 separation method Methods 0.000 description 5
- 238000007873 sieving Methods 0.000 description 5
- 239000006228 supernatant Substances 0.000 description 5
- 238000005303 weighing Methods 0.000 description 5
- 239000011247 coating layer Substances 0.000 description 4
- 239000007770 graphite material Substances 0.000 description 4
- 239000007791 liquid phase Substances 0.000 description 4
- 125000004122 cyclic group Chemical group 0.000 description 3
- 239000007772 electrode material Substances 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000010410 layer Substances 0.000 description 3
- 229910021382 natural graphite Inorganic materials 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 239000012300 argon atmosphere Substances 0.000 description 2
- 230000002238 attenuated effect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 125000004432 carbon atom Chemical group C* 0.000 description 2
- 239000003575 carbonaceous material Substances 0.000 description 2
- 238000012512 characterization method Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- 230000008929 regeneration Effects 0.000 description 2
- 230000007847 structural defect Effects 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 239000006230 acetylene black Substances 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 238000009831 deintercalation Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
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- 239000000428 dust Substances 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 229910021389 graphene Inorganic materials 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 238000009854 hydrometallurgy Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000005486 organic electrolyte Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 238000009853 pyrometallurgy Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000004626 scanning electron microscopy Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/20—Graphite
- C01B32/21—After-treatment
- C01B32/215—Purification; Recovery or purification of graphite formed in iron making, e.g. kish graphite
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/20—Graphite
- C01B32/21—After-treatment
-
- 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
-
- 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
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Geology (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Inorganic Chemistry (AREA)
- Environmental & Geological Engineering (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Carbon And Carbon Compounds (AREA)
Abstract
The application discloses a method for regenerating negative graphite in waste batteries, and relates to the field of lithium ion battery negative material recovery. Comprising the following steps: acid treatment is carried out on the disassembled graphite in the waste batteries under mechanical stirring to obtain primarily purified graphite; placing the primarily purified graphite in a tube furnace, calcining under inert atmosphere and high temperature, and modifying the graphite surface in situ; and placing graphite into a ball milling tank containing coating liquid, carrying out surface coating in a wet ball milling mode, drying to remove solvent, and placing the dried product into a tube furnace for carbonization treatment to obtain the regenerated graphite anode material. The method is used for realizing the recycling of the waste graphite cathode, so that the technical problems of larger particle size, uneven coating, lower capacity when the graphite cathode material obtained by the existing method is used as the cathode material in a lithium ion battery, lower initial efficiency, quicker capacity attenuation and the like are solved, and the problem of black pollution to the environment caused by the fact that the waste graphite cathode cannot be effectively utilized can be avoided.
Description
Technical Field
The application discloses a graphite regeneration method in waste batteries, and relates to the field of lithium ion battery negative electrode material recovery.
Background
In recent years, new energy markets have rapidly developed, and the holding capacity of lithium ion batteries has rapidly increased. The power lithium battery is the first power battery of the new energy automobile at present by virtue of the advantages of high energy density, long cycle life, low self discharge, environmental protection and the like since the industrialization of the Sony company. Meanwhile, an energy storage technology based on lithium battery promotes electric wave in the traffic field, and simultaneously increases the demand of lithium ion battery material resources and aggravates the scarcity of the resources. How to recycle the waste lithium ion batteries by using a simple and green method is an urgent problem to be solved in the sustainable development link of the industrial chain in the new energy field.
In recent years, the waste lithium ion battery anode material has been industrially produced by the mature technologies of hydrometallurgy, pyrometallurgy and the like. In contrast, lithium ion battery cathodes are often buried or incinerated at high temperatures, and this unreasonable treatment method exacerbates the deterioration of environmental problems such as dust pollution and greenhouse effect. In addition, as a key strategic resource, the global available graphite is only 2.5 hundred million tons, and if the waste lithium battery cathode material cannot be properly treated, huge resource waste and economic loss are caused. More importantly, if not handled carefully, with the increasing number of waste lithium ion batteries, the lithium, heavy metal ions (nickel, cobalt, manganese) and organic electrolyte (lithium hexafluorophosphate, carbonate) remaining in the waste graphite will cause catastrophic consequences such as fire, explosion, leakage of harmful substances, etc. From the aspects of resource shortage, serious environmental pollution, potential safety hazard and the like, the regeneration of the anode material of the waste lithium ion battery and the resource utilization of the product thereof should be continuously concerned.
At present, materials such as silicon base, lithium titanate and the like only account for about 9% of the market of commercial negative electrode materials, the graphite proportion is as high as 90%, the rising trend is presented, the future market is very large, and the regeneration and repair of the waste graphite negative electrode materials become hot spots in the field of battery recovery. Although the surface structure and the composition can be changed due to long-time charge and discharge cycles, the bulk structure of the graphite material shows relatively high structural stability, and can meet the secondary utilization of the lithium ion battery through deep purification and structural repair. Aiming at deep purification and structural repair of the anode material, searching for a proper recovery process creates additional economic value, and the recovery process of the anode material of the waste lithium ion battery in the prior art has the following problems:
1. the graphite recovered from the leached residue contains more metal impurities, which results in difficult recovery, low recovery rate, and the recovered graphite cannot meet the raw material grade required for battery manufacturing;
2. the expansion of interlayer spacing, the change of lattice structure and the doping of impurities are the remarkable characteristics of the negative electrode graphite after the failure of the waste lithium ion battery, so that the surface structure and the composition of graphite particles are remarkably changed, the performance of the regenerated graphite is limited, and meanwhile, the structural repair of the waste graphite in the recovery process of the waste lithium ion battery is not explored.
In view of the foregoing, there is a need for an efficient regeneration method to repair the structural defects of waste graphite, so that the regenerated graphite achieves higher electrochemical activity and excellent cycle stability.
Disclosure of Invention
The application discloses a graphite regeneration method in waste batteries, which solves the problem of recycling graphite in negative electrode materials of lithium batteries.
In order to achieve the above purpose, the following technical scheme is adopted:
a graphite regeneration method in waste batteries comprises the following steps:
s1, raw materials: firstly, removing a negative electrode piece from a waste lithium ion battery, directly scraping a negative electrode material on the surface of the negative electrode piece, then soaking the recovered negative electrode material in an organic solvent, continuously stirring to remove electrolyte on the surface of the negative electrode piece, and then filtering, drying, crushing and screening to obtain a graphite negative electrode material;
s2, acid leaching pretreatment: the graphite cathode material obtained by pretreatment in the step S1 is used as a raw material, metal impurities in the graphite cathode material are fully dissolved into a solution phase through acid leaching and mechanical stirring, then metal ions entering the solution phase are converted into soluble metal salt sulfate, deionized water is used for repeatedly cleaning until the pH value is 6-8, and vacuum drying is carried out at 80 ℃ to obtain primarily purified graphite;
s3, high-temperature calcination: placing the graphite subjected to primary purification in the step S2 in a tube furnace, calcining in an inert atmosphere to completely crack and convert binder organic matters remained on the surface of the graphite into amorphous carbon, and modifying the amorphous carbon on the surface of the graphite in situ to obtain secondary purified graphite;
s4, coating and secondary calcining: soaking the graphite secondarily purified in the step S3 in a coating liquid containing a carbon source, carrying out surface coating in a wet ball milling mode, evaporating and drying to remove a solvent, placing the carbon coating material attached to the surface in a tube furnace, carrying out secondary calcination in an inert atmosphere, cooling and screening to obtain the battery-grade regenerated graphite anode material.
Preferably, the organic solvent in step S1 is one of dimethyl carbonate, ethylene carbonate and propylene carbonate.
Preferably, the screen mesh number of the screening treatment in step S1 is 100 mesh.
Preferably, in step S2, sulfuric acid is used to acid-wash the graphite anode material, and the concentration of the acid solution is 0.5-4mol/L.
Preferably, the mass ratio of graphite to acid solution in the step S2 is 1 (1-10) g/ml, the reaction time of the acid leaching process is 0.5-6h, and the treatment temperature is 25-80 ℃.
Preferably, the inert atmosphere in the step S3 is one of argon and nitrogen, the temperature rising rate in the calcining process is 2-5 ℃/min, the calcining temperature is 800-1000 ℃, and the calcining time is 3-6h.
Preferably, in the step S4, the ball-material ratio of the materials in the ball milling tank is 1:5, the rotating speed is 350-500r/min, and the ball milling time is 6-10h.
Preferably, the carbon source coated in the step S4 is asphalt, the coating solvent is one of tetrahydrofuran, pyridine and toluene, and the addition amount of the asphalt is 3-15 wt% of the mass of the graphite.
Preferably, the product in the step S4 is placed in a tube furnace, one of argon and nitrogen is used, the heating rate in the high-temperature treatment process is 2-5 ℃/min, the calcining temperature is 800-1000 ℃, and the calcining time is 3-6h.
Preferably, the screen mesh number of the screening treatment in step S4 is 100 mesh.
Compared with the prior art, the application has the beneficial effects that:
1. according to the scheme, a graphite recycling method is designed, and graphite anode materials recycled in waste lithium ion batteries are soaked in an organic solvent, so that electrolyte on the surface of the anode materials is removed; the pretreated graphite is used as a raw material for acid washing and purification, so that an acid solution and metal impurities fully react to form soluble metal salts, residual metal impurities in the graphite are effectively removed, the purity of the graphite is improved, and the problems that the residual metal impurities are more and the graphite recovery is not facilitated are solved. Then, the powder is calcined by high-temperature roasting, so that organic residues such as polyvinylidene fluoride and acetylene black are further carbonized to be converted into amorphous carbon, most of F, P, S and other volatile impurities are removed, and the purity of the material is improved. In addition, carbon atoms are rearranged in the high-temperature calcination process, so that the defects of the graphite structure are repaired; finally, a layer of carbon material is coated on the surface of the waste graphite by a ball milling process and a rapid heating technology, surface reconstruction is carried out, and the added asphalt forms amorphous carbon to fill the defects and pores originally formed by long-time charge and discharge cyclic use, so that the specific surface area is reduced, and the electrochemical activity and the cyclic stability of the material are improved.
2. Compared with the prior art, the method has the advantages of simple process, low recovery energy consumption and cost, high purity of the recovered material, environment-friendly process and no pollution. After the organic solvent is cleaned, acid leaching is performed, purification is performed, and high-temperature calcination is performed, impurities such as electrolyte, metal ions, binders and the like attached to the surface of graphite are efficiently removed, and the purity of the material is obviously improved. In the scheme, the ball milling coating process not only can reduce the particle size of graphite, but also can enable carbon materials dispersed in the graphite to be uniformly attached to the surface of the material, so that the uniform coating of the graphite is realized; the traditional graphite repairing process flow relates to ball milling screening and liquid phase cladding process flow is combined into a whole, so that the recovery flow is simplified, and the process flow is simple and efficient; more importantly, the method can solve the technical problems that the particle size of the graphite material obtained by the existing graphite recovery method is too large, the coating is uneven, the graphite structure of the battery can not be maintained when the battery is used as a negative electrode material, the capacity is rapidly attenuated, and the like. Solves two problems of graphite recovery and restoration at one time, and has important guiding significance for the resource utilization of waste lithium batteries. The assembled half-cell is superior to the graphite material of the traditional liquid phase repair in specific capacity, rate capability and long cycle performance.
3. The method provided by the scheme is simple in process, easy for large-scale industrial production, low in material recovery cost and high in recovery rate, and the prepared graphene-coated carbon anode material recovered from waste has excellent high-current charge-discharge performance, excellent cycling stability, high first coulomb efficiency and high charge-discharge specific capacity.
Drawings
FIG. 1 is a scanning electron microscope image of acid treated graphite and reclaimed graphite produced by the present application;
FIG. 2 is a flow chart of a conventional regeneration method of comparative examples 1 and 2;
FIG. 3 is a flow chart of the regeneration method of examples 1-4.
Description of the embodiments
The application is described in further detail below with reference to the attached drawings and embodiments:
example 1
A graphite regeneration method in waste batteries comprises the following steps:
s1, raw materials: firstly, removing a negative electrode plate from a waste lithium ion battery, directly scraping graphite negative electrode materials on the surface of the negative electrode plate, then, soaking the recovered graphite negative electrode materials in dimethyl carbonate, continuously stirring for 2 hours, filtering out the dimethyl carbonate, and obtaining the graphite negative electrode materials with 100 meshes through drying and sieving by a 100-mesh sieve.
S2, acid leaching pretreatment: and (2) taking the graphite anode material pretreated in the step (S1) as a raw material, placing graphite into sulfuric acid solution with the concentration of 0.5mol/L, controlling the mass ratio of the graphite to the acid solution to be 1:1g/ml, heating the graphite to 25 ℃ by an oil bath, and uniformly stirring for 0.5h. And (3) after the obtained slurry is subjected to suction filtration, transferring the slurry to a vacuum drying oven and drying the slurry for 5 hours at 80 ℃. The impurities in the material are fully dissolved by mechanical stirring (stirring speed is 200 rpm/min), metal ions in the graphite are converted into soluble metal salts, deionized water is used for repeatedly cleaning until the pH value is 6-8, and vacuum drying is carried out at the temperature of 80 ℃ to obtain the graphite which is primarily purified.
S3, high-temperature calcination: and (2) placing the graphite subjected to primary purification in the step (S2) in a tube furnace, calcining for 3 hours in an argon atmosphere at a speed of 2 ℃/min from room temperature to 800 ℃, cooling the tube furnace to below room temperature, and taking out the tube furnace to convert binder organic matters in the product into amorphous carbon, and modifying the amorphous carbon on the surface of the graphite in situ to obtain the graphite subjected to secondary purification.
S4, coating and secondary calcining: firstly, weighing 3wt% of medium-temperature asphalt, placing the medium-temperature asphalt into a beaker, adding 25ml of toluene, uniformly stirring for 30min, placing the mixture into a centrifuge tube for centrifugal separation, removing asphalt which is insoluble in toluene solution, and pouring supernatant into a 500ml ball milling tank. Soaking graphite in the step S3 in a ball milling tank containing 25ml of toluene, then ball milling for 6 hours at a rotating speed of 350rpm/min by adopting a wet ball milling mode, transferring to a vacuum drying oven for drying for 10 hours at 100 ℃ after the solvent volatilizes completely, finally placing the dried product in a tubular furnace, calcining for 3 hours at a speed of 2 ℃/min from room temperature to 800 ℃ in an argon atmosphere, cooling to below room temperature along with the furnace, taking out, sieving with a 100-mesh sieve, and obtaining the battery-grade regenerated graphite anode material.
Example 2
A graphite regeneration method in waste batteries comprises the following steps:
s1, raw materials: firstly, removing a negative electrode plate from a waste lithium ion battery, directly scraping off a natural graphite negative electrode material on the surface of the negative electrode plate, then, soaking the recovered graphite negative electrode material in ethylene carbonate, continuously stirring for 3 hours, filtering ethylene carbonate, drying, and sieving with a 100-mesh sieve to obtain a 100-mesh graphite negative electrode material;
s2, acid leaching pretreatment: and (2) taking the graphite anode material pretreated in the step (S1) as a raw material, placing graphite into sulfuric acid solution with the concentration of 2mol/L, controlling the mass ratio of the graphite to the acid solution to be 1:5g/ml, heating the graphite to 40 ℃ by an oil bath, and uniformly stirring for 3 hours. And (3) after the obtained slurry is subjected to suction filtration, transferring the slurry to a vacuum drying oven and drying the slurry for 5 hours at 80 ℃. Fully dissolving impurities in the material by mechanical stirring (stirring speed is 300 rpm/min), converting metal ions in graphite into soluble metal salts, repeatedly cleaning with deionized water to pH value of 6-8, and vacuum drying at 80 ℃ to obtain primarily purified graphite.
S3, high-temperature calcination: and (2) placing the graphite subjected to primary purification in the step (S2) in a tube furnace, calcining for 4 hours in a nitrogen atmosphere at a speed of 3 ℃/min from room temperature to 900 ℃, cooling the tube furnace to below room temperature, and taking out the tube furnace to convert binder organic matters in the product into amorphous carbon, and modifying the amorphous carbon on the surface of the graphite in situ to obtain the graphite subjected to secondary purification.
S4, coating and secondary calcining: firstly, weighing 5wt% of medium-temperature asphalt, placing the medium-temperature asphalt into a beaker, adding 25ml of pyridine, uniformly stirring for 30min, placing the mixture into a centrifuge tube for centrifugal separation, removing asphalt which is insoluble in pyridine solution, and pouring supernatant into a 500ml ball milling tank. Soaking graphite in the step S2 in a ball milling tank, then ball milling for 8 hours at a rotating speed of 400rpm/min in a wet ball milling mode, transferring to a vacuum drying oven for drying at 100 ℃ for 10 hours after the solvent volatilizes completely, placing the material with asphalt attached to the surface in a tube furnace, and heating to 900 ℃ for carbonization for 4 hours at a speed of 3 ℃/min in a nitrogen atmosphere to obtain the regenerated graphite anode material.
Example 3
A graphite regeneration method in waste batteries comprises the following steps:
s1, raw materials: firstly, removing a negative electrode plate from a waste lithium ion battery, directly scraping graphite negative electrode materials on the surface of the negative electrode plate, then, soaking the recovered graphite negative electrode materials in propylene carbonate, continuously stirring for 3 hours, filtering the propylene carbonate, drying and sieving with a 100-mesh sieve to obtain a 100-mesh graphite negative electrode material;
s2, acid leaching pretreatment: and (2) taking the graphite anode material pretreated in the step (S1) as a raw material, placing graphite into sulfuric acid solution with the concentration of 4mol/L, controlling the mass ratio of the graphite to the acid solution to be 1:10g/ml, heating the graphite to 60 ℃ by an oil bath, and uniformly stirring for 6 hours. And (3) after the obtained slurry is subjected to suction filtration, transferring the slurry to a vacuum drying oven and drying the slurry for 5 hours at 80 ℃. Fully dissolving impurities in the material by mechanical stirring (stirring speed is 300 rpm/min), converting metal ions in graphite into soluble metal salts, repeatedly cleaning with deionized water to pH value of 6-8, and vacuum drying at 80 ℃ to obtain primarily purified graphite.
S3, high-temperature calcination: and (2) placing the graphite subjected to primary purification in the step (S2) in a tube furnace, calcining for 6 hours at a temperature of between room temperature and 1000 ℃ at a speed of 5 ℃/min in a nitrogen atmosphere, cooling the tube furnace to below the room temperature, and taking out the tube furnace to convert binder organic matters in the product into amorphous carbon, and modifying the surface of the graphite in situ to obtain the graphite subjected to secondary purification.
S4, coating and secondary calcining: firstly, weighing 7wt% of medium-temperature asphalt, placing the medium-temperature asphalt into a beaker, adding 25ml of tetrahydrofuran, uniformly stirring for 30min, placing the mixture into a centrifuge tube for centrifugal separation, removing asphalt which is insoluble in tetrahydrofuran solution, and pouring supernatant into a 500ml ball milling tank. Soaking graphite in the step S2 in a ball milling tank, then ball milling for 10 hours at a rotating speed of 500rpm/min by adopting a wet ball milling method, transferring to a vacuum drying oven for drying for 10 hours at 100 ℃, placing a material with asphalt attached to the surface in a tube furnace, and heating to 1000 ℃ for carbonization for 6 hours at a speed of 5 ℃/min in a nitrogen atmosphere to obtain the regenerated graphite anode material.
Example 4
A graphite regeneration method in waste batteries comprises the following steps:
s1, raw materials: firstly, removing a negative electrode plate from a waste lithium ion battery, directly scraping natural graphite negative electrode materials on the surface of the negative electrode plate, then, soaking the recovered natural graphite negative electrode materials in dimethyl carbonate, continuously stirring for 3 hours, filtering propylene carbonate, drying, and sieving with a 100-mesh sieve to obtain a 100-mesh graphite negative electrode material;
s2, acid leaching pretreatment: and (2) taking the graphite anode material pretreated in the step (S1) as a raw material, placing graphite into sulfuric acid solution with the concentration of 4mol/L, controlling the mass ratio of the graphite to the acid solution to be 1:5g/ml, heating the graphite to 80 ℃ in an oil bath, and uniformly stirring for 6 hours. And (3) after the obtained slurry is subjected to suction filtration, transferring the slurry to a vacuum drying oven and drying the slurry for 5 hours at 80 ℃. Fully dissolving impurities in the material by mechanical stirring (stirring speed is 300 rpm/min), converting metal ions in graphite into soluble metal salts, repeatedly cleaning with deionized water to pH value of 6-8, and vacuum drying at 80 ℃ to obtain primarily purified graphite.
S3, high-temperature calcination: and (2) placing the graphite subjected to primary purification in the step (S2) in a tube furnace, calcining for 6 hours at a temperature of between room temperature and 1000 ℃ at a speed of 5 ℃/min in a nitrogen atmosphere, cooling the tube furnace to below the room temperature, and taking out the tube furnace to convert binder organic matters in the product into amorphous carbon, and modifying the surface of the graphite in situ to obtain the graphite subjected to secondary purification.
S4, coating and secondary calcining: firstly, weighing 15wt% of medium-temperature asphalt, placing the medium-temperature asphalt into a beaker, adding 25ml of tetrahydrofuran, uniformly stirring for 30min, placing the mixture into a centrifuge tube for centrifugal separation, removing asphalt which is insoluble in tetrahydrofuran solution, and pouring supernatant into a 500ml ball milling tank. Soaking graphite in the step S2 in a ball milling tank, then ball milling for 10 hours at a rotating speed of 500rpm/min by adopting a wet ball milling method, transferring to a vacuum drying oven for drying for 10 hours at 100 ℃, placing a material with asphalt attached to the surface in a tube furnace, and heating to 1000 ℃ for carbonization for 6 hours at a speed of 5 ℃/min in a nitrogen atmosphere to obtain the regenerated graphite anode material.
The technical principle of the scheme is as follows:
according to the method for recycling graphite in the waste batteries, firstly, metal impurities in graphite slag are removed by acid washing, and then, the reaction is carried out by controlling the temperature, the stirring speed and the heat preservation time, so that the dissolution of indissolvable metal impurities is promoted. Meanwhile, the scheme also controls the acid solution, the treatment time and the temperature of the acid solution, promotes the collision reaction between acid molecules and metal impurities, thereby improving the impurity removal efficiency and obtaining the primarily purified graphite after the treatment.
Then, the preliminarily purified graphite is calcined at high temperature, so that the binder organic matters remained in the graphite are fully contacted with inert gases, completely cracked and converted into amorphous carbon, and the amorphous carbon is modified on the surface of the graphite in situ; meanwhile, by precisely controlling the calcination temperature and the calcination time, the carbon atoms are re-shot while the materials are purified, and the defects of the graphite structure are repaired. And by controlling the calcination temperature, the heating rate and the time, the organic matters in the waste graphite anode material are decomposed and carbonized, the form of graphite is fixed, and the structural defect of graphite is recovered.
Finally, asphalt with specific weight is added into graphite, an asphalt coating layer is formed on the surface of the graphite in a wet ball milling mixing and high-temperature calcining mode, and cracks formed on the surface of the directly recovered negative electrode material due to long-time charge and discharge cyclic use are repaired, so that the negative electrode material has excellent electrochemical activity and stable circulation.
The preparation method of the asphalt coating liquid is not particularly limited, and the technical scheme known in the art can be adopted. According to the scheme, the asphalt is dissolved by using the organic solvents, so that the components are uniformly mixed, and the coating effect of the asphalt on the regenerated graphite is improved. Meanwhile, the mixing parameters of the graphite and the asphalt coating liquid are controlled in the range, so that a uniform asphalt coating layer can be formed on the surface of the graphite, the coating layer is smoother, the coating effect is better, and the first efficiency of a battery taking the recycled graphite as a negative electrode is improved; and the scheme also controls the temperature, time and heating rate of carbonization treatment, is favorable for carbonization of the carbonization process, can lead asphalt to be carbonized completely, forms an integrated structure with graphite, improves the surface defect of the graphite, improves the surface property of graphite materials, can further improve the first efficiency of the battery taking the recycled graphite as a negative electrode, and obtains better cycle performance and multiplying power performance.
Comparative example 1
The comparative example adopts a traditional regeneration method, a certain amount of waste graphite is weighed and placed in sulfuric acid solution with the concentration of 4mol/L, the mass ratio of the graphite to the acid solution is controlled to be 1:5g/ml, and the oil bath is heated to 60 ℃ and is uniformly stirred for 6 hours; and (3) after the obtained slurry is subjected to suction filtration, transferring the slurry to a vacuum drying oven and drying the slurry for 5 hours at 80 ℃. And (3) placing the dried graphite in a tube furnace, calcining for 6 hours in a nitrogen atmosphere at a temperature of 5 ℃/min from room temperature to 1000 ℃, cooling the tube furnace to below room temperature, and taking out the tube furnace to convert binder organic matters in the product into amorphous carbon, and modifying the surface of the graphite in situ to obtain the graphite anode material.
Comparative example 2
The comparative example adopts a traditional regeneration method, a certain amount of waste graphite is weighed and placed in sulfuric acid solution with the concentration of 2mol/L, the mass ratio of the graphite to the acid solution is controlled to be 1:5g/ml, and the oil bath is heated to 60 ℃ and is uniformly stirred for 6 hours; and (3) after the obtained slurry is subjected to suction filtration, transferring the slurry to a vacuum drying oven and drying the slurry for 5 hours at 80 ℃. And (3) placing the dried graphite in a tubular furnace, heating to 800 ℃ along with the furnace, preserving heat for 4 hours, cooling to below room temperature along with the furnace, and taking out.
Weighing 5wt% of medium-temperature asphalt, placing the asphalt into a beaker, adding 25ml of pyridine, uniformly stirring for 30min, placing the mixture into a centrifuge tube for centrifugal separation, removing asphalt which is insoluble in pyridine solution, and pouring supernatant into the beaker; the pretreated graphite is added into the coating liquid in batches, and the rotating speed can be properly adjusted in the period; after stirring for 4 hours at room temperature, the temperature of the oil bath is raised to 70 ℃, and stirring is continued until the solvent is completely volatilized; and (3) placing the material with the asphalt attached to the surface into a tube furnace, and heating to 900 ℃ at a speed of 5 ℃/min under the nitrogen atmosphere to carbonize for 4 hours to obtain the battery grade regenerated graphite anode material.
The products obtained in examples 1-4 and comparative examples 1-2 were used for characterization, and the characterization results obtained are shown below.
As shown in FIG. 1, the particle size of the acid-treated graphite (a in FIG. 1) and the regenerated graphite (b in FIG. 1) was about 15-20 μm in scanning electron microscopy. The surface of the graphite subjected to preliminary purification has cracks and impurity adhesion objects with different degrees; after asphalt is repaired, the surface defects of the regenerated graphite are gradually reduced, and a layer of compact and round amorphous carbon is gradually formed on the surface of the graphite, so that the intercalation/deintercalation of lithium ions is facilitated, and the electrochemical performance is good.
As shown in the following table 1,
table 1: electrical properties of regenerated graphite
The graphite prepared in the examples was used as a negative electrode material, and a lithium sheet was used as a counter electrode, and assembled into a button cell. The charge-discharge cycle test was performed at a current density of 0.5C (1c=372 mA g-1) in a voltage range of 0.01 to 2V at 20 to 25 ℃. From table 1 the following conclusions can be drawn: (1) The particle size of graphite is reduced, which is beneficial to shortening the lithium ion transmission path, thereby improving the cycle stability of the electrode material. (2) Compared with the traditional liquid phase coating, the ball milling coating process can realize uniform coating of the carbon coating, not only can stabilize the electrode structure, but also can improve the rate capability of the electrode material. (3) The thickness of asphalt coating is reasonably regulated and controlled, and the overall performance of graphite is better optimized. The thickness of the coating layer is critical to the structure of the electrode material. The asphalt coating content is excessive, and the formed amorphous carbon content is increased, so that the overall coulombic efficiency of the coated material is reduced; the coating formed by asphalt is too weak to support the graphite structure, and the graphite layers are peeled off in the subsequent circulation process, so that the capacity is rapidly attenuated.
As shown in fig. 2 and 3, the ball milling and coating processes of examples 1 to 4 can combine ball milling and screening and liquid phase coating in the conventional processes of comparative examples 1 and 2 into one flow, the production process is simple and efficient and expandable, and the obtained product has excellent electrochemical properties, and the work provides an effective strategy for industrial graphite recovery, provides a new way for preparing high-performance lithium ion battery graphite cathodes, and has good commercial application prospects.
The foregoing is merely exemplary of the present application and the details of construction and/or the general knowledge of the structures and/or characteristics of the present application as it is known in the art will not be described in any detail herein. It should be noted that modifications and improvements can be made by those skilled in the art without departing from the structure of the present application, and these should also be considered as the scope of the present application, which does not affect the effect of the implementation of the present application and the utility of the patent. The protection scope of the present application is subject to the content of the claims, and the description of the specific embodiments and the like in the specification can be used for explaining the content of the claims.
Claims (10)
1. A graphite regeneration method in waste batteries is characterized in that: the method comprises the following steps:
s1, raw materials: firstly, removing a negative electrode piece from a waste lithium ion battery, directly scraping a negative electrode material on the surface of the negative electrode piece, then soaking the recovered negative electrode material in an organic solvent, continuously stirring to remove electrolyte on the surface of the negative electrode piece, and then filtering, drying, crushing and screening to obtain a graphite negative electrode material;
s2, acid leaching pretreatment: the graphite cathode material obtained by pretreatment in the step S1 is used as a raw material, metal impurities in the graphite cathode material are fully dissolved into a solution phase through acid leaching and mechanical stirring, then metal ions entering the solution phase are converted into soluble metal salt sulfate, deionized water is used for repeatedly cleaning until the pH value is 6-8, and vacuum drying is carried out at 80 ℃ to obtain primarily purified graphite;
s3, high-temperature calcination: placing the graphite subjected to primary purification in the step S2 in a tube furnace, calcining in an inert atmosphere to completely crack and convert binder organic matters remained on the surface of the graphite into amorphous carbon, and modifying the amorphous carbon on the surface of the graphite in situ to obtain secondary purified graphite;
s4, coating and secondary calcining: soaking the graphite secondarily purified in the step S3 in a coating liquid containing a carbon source, carrying out surface coating in a wet ball milling mode, evaporating and drying to remove a solvent, placing the carbon coating material attached to the surface in a tube furnace, carrying out secondary calcination in an inert atmosphere, cooling and screening to obtain the battery-grade regenerated graphite anode material.
2. A method for regenerating graphite in a waste battery as claimed in claim 1, wherein: the organic solvent in the step S1 is one of dimethyl carbonate, ethylene carbonate and propylene carbonate.
3. A method for regenerating graphite in a waste battery as claimed in claim 2, wherein: the number of meshes of the screening treatment in step S1 is 100 mesh.
4. A method for regenerating graphite in a waste battery as claimed in claim 1, wherein: in the step S2, sulfuric acid is used for pickling the graphite anode material, and the concentration of the acid solution is 0.5-4mol/L.
5. The method for regenerating graphite in a waste battery as claimed in claim 4, wherein: in the step S2, the mass ratio of graphite to acid solution is 1 (1-10) g/ml, the reaction time of the acid leaching process is 0.5-6h, and the treatment temperature is 25-80 ℃.
6. A method for regenerating graphite in a waste battery as claimed in claim 1, wherein: in the step S3, the inert atmosphere is one of argon and nitrogen, the temperature rising rate in the calcining process is 2-5 ℃/min, the calcining temperature is 800-1000 ℃, and the calcining time is 3-6h.
7. A method for regenerating graphite in a waste battery as claimed in claim 1, wherein: in the step S4, the ball-material ratio of the materials in the ball milling tank is 1:5, the rotating speed is 350-500r/min, and the ball milling time is 6-10h.
8. The method for regenerating graphite in a waste battery as claimed in claim 7, wherein: in the step S4, the coated carbon source is asphalt, the coating solvent is one of tetrahydrofuran, pyridine and toluene, and the addition amount of the asphalt is 3-15 wt% of the mass of graphite.
9. The method for regenerating graphite in a waste battery as claimed in claim 8, wherein: and (3) placing the product obtained in the step S4 in a tube furnace, wherein one of argon and nitrogen is used, the heating rate in the high-temperature treatment process is 2-5 ℃/min, the calcining temperature is 800-1000 ℃, and the calcining time is 3-6h.
10. A method for regenerating graphite in a waste battery as claimed in claim 1, wherein: the number of meshes of the screening treatment in step S4 is 100 mesh.
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| CN117594899B (en) * | 2024-01-18 | 2024-04-12 | 江苏杰成新能源科技有限公司 | Deep impurity removal and repair regeneration method for waste battery cathode material |
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