CN116387483A - Si@C@MOFs composite material and preparation method thereof, negative electrode material, negative electrode plate and lithium battery - Google Patents
Si@C@MOFs composite material and preparation method thereof, negative electrode material, negative electrode plate and lithium battery Download PDFInfo
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- 239000002131 composite material Substances 0.000 title claims abstract description 43
- 238000002360 preparation method Methods 0.000 title claims abstract description 32
- 239000007773 negative electrode material Substances 0.000 title claims abstract description 17
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 13
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 13
- 239000000463 material Substances 0.000 claims abstract description 143
- 239000012621 metal-organic framework Substances 0.000 claims abstract description 98
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 57
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 45
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 39
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 34
- 239000010703 silicon Substances 0.000 claims abstract description 34
- 150000003377 silicon compounds Chemical class 0.000 claims abstract description 29
- 238000000034 method Methods 0.000 claims description 31
- 239000002210 silicon-based material Substances 0.000 claims description 23
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 21
- 239000003575 carbonaceous material Substances 0.000 claims description 20
- 239000013110 organic ligand Substances 0.000 claims description 20
- 229910052751 metal Inorganic materials 0.000 claims description 17
- 239000002184 metal Substances 0.000 claims description 17
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 16
- 150000003839 salts Chemical class 0.000 claims description 16
- 239000002904 solvent Substances 0.000 claims description 14
- YSWBFLWKAIRHEI-UHFFFAOYSA-N 4,5-dimethyl-1h-imidazole Chemical compound CC=1N=CNC=1C YSWBFLWKAIRHEI-UHFFFAOYSA-N 0.000 claims description 12
- KKEYFWRCBNTPAC-UHFFFAOYSA-N Terephthalic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-N 0.000 claims description 12
- QMKYBPDZANOJGF-UHFFFAOYSA-N benzene-1,3,5-tricarboxylic acid Chemical compound OC(=O)C1=CC(C(O)=O)=CC(C(O)=O)=C1 QMKYBPDZANOJGF-UHFFFAOYSA-N 0.000 claims description 12
- 239000003607 modifier Substances 0.000 claims description 12
- 238000009835 boiling Methods 0.000 claims description 11
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims description 10
- 125000005336 allyloxy group Chemical group 0.000 claims description 10
- 238000004519 manufacturing process Methods 0.000 claims description 10
- 229910052708 sodium Inorganic materials 0.000 claims description 10
- 239000011734 sodium Substances 0.000 claims description 10
- 238000003756 stirring Methods 0.000 claims description 10
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- 239000011248 coating agent Substances 0.000 claims description 9
- 238000000576 coating method Methods 0.000 claims description 9
- 238000005245 sintering Methods 0.000 claims description 9
- 239000013154 zeolitic imidazolate framework-8 Substances 0.000 claims description 9
- MFLKDEMTKSVIBK-UHFFFAOYSA-N zinc;2-methylimidazol-3-ide Chemical compound [Zn+2].CC1=NC=C[N-]1.CC1=NC=C[N-]1 MFLKDEMTKSVIBK-UHFFFAOYSA-N 0.000 claims description 9
- 239000002245 particle Substances 0.000 claims description 8
- 239000000243 solution Substances 0.000 claims description 8
- ONDPHDOFVYQSGI-UHFFFAOYSA-N zinc nitrate Chemical compound [Zn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ONDPHDOFVYQSGI-UHFFFAOYSA-N 0.000 claims description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 7
- 229910021645 metal ion Inorganic materials 0.000 claims description 7
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 7
- ZOIORXHNWRGPMV-UHFFFAOYSA-N acetic acid;zinc Chemical compound [Zn].CC(O)=O.CC(O)=O ZOIORXHNWRGPMV-UHFFFAOYSA-N 0.000 claims description 5
- 229940011182 cobalt acetate Drugs 0.000 claims description 5
- QAHREYKOYSIQPH-UHFFFAOYSA-L cobalt(II) acetate Chemical compound [Co+2].CC([O-])=O.CC([O-])=O QAHREYKOYSIQPH-UHFFFAOYSA-L 0.000 claims description 5
- LUIGSJYSMIUMPK-UHFFFAOYSA-N propane-1-sulfonoperoxoic acid Chemical compound CCCS(=O)(=O)OO LUIGSJYSMIUMPK-UHFFFAOYSA-N 0.000 claims description 5
- XZTJQQLJJCXOLP-UHFFFAOYSA-M sodium;decyl sulfate Chemical compound [Na+].CCCCCCCCCCOS([O-])(=O)=O XZTJQQLJJCXOLP-UHFFFAOYSA-M 0.000 claims description 5
- BDHFUVZGWQCTTF-UHFFFAOYSA-M sulfonate Chemical compound [O-]S(=O)=O BDHFUVZGWQCTTF-UHFFFAOYSA-M 0.000 claims description 5
- 239000004246 zinc acetate Substances 0.000 claims description 5
- 239000007864 aqueous solution Substances 0.000 claims description 4
- UFMZWBIQTDUYBN-UHFFFAOYSA-N cobalt dinitrate Chemical compound [Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O UFMZWBIQTDUYBN-UHFFFAOYSA-N 0.000 claims description 4
- 229910001981 cobalt nitrate Inorganic materials 0.000 claims description 4
- 229910000152 cobalt phosphate Inorganic materials 0.000 claims description 4
- ZBDSFTZNNQNSQM-UHFFFAOYSA-H cobalt(2+);diphosphate Chemical compound [Co+2].[Co+2].[Co+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O ZBDSFTZNNQNSQM-UHFFFAOYSA-H 0.000 claims description 4
- 239000011701 zinc Substances 0.000 claims description 4
- 229910052725 zinc Inorganic materials 0.000 claims description 4
- XTVVROIMIGLXTD-UHFFFAOYSA-N copper(II) nitrate Chemical compound [Cu+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O XTVVROIMIGLXTD-UHFFFAOYSA-N 0.000 claims description 3
- OPQARKPSCNTWTJ-UHFFFAOYSA-L copper(ii) acetate Chemical compound [Cu+2].CC([O-])=O.CC([O-])=O OPQARKPSCNTWTJ-UHFFFAOYSA-L 0.000 claims description 3
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 claims description 3
- 230000000630 rising effect Effects 0.000 claims description 2
- 239000010410 layer Substances 0.000 abstract description 39
- 239000005543 nano-size silicon particle Substances 0.000 abstract description 24
- 238000003763 carbonization Methods 0.000 abstract description 10
- 230000008901 benefit Effects 0.000 abstract description 8
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- 239000010405 anode material Substances 0.000 description 12
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- 239000000203 mixture Substances 0.000 description 9
- 230000008569 process Effects 0.000 description 9
- 238000012360 testing method Methods 0.000 description 8
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 7
- 230000001351 cycling effect Effects 0.000 description 7
- 229910001416 lithium ion Inorganic materials 0.000 description 7
- 238000011056 performance test Methods 0.000 description 7
- 238000005229 chemical vapour deposition Methods 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 5
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 4
- 239000011889 copper foil Substances 0.000 description 4
- 239000013078 crystal Substances 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000010000 carbonizing Methods 0.000 description 3
- 239000010406 cathode material Substances 0.000 description 3
- 239000003792 electrolyte Substances 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
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- 238000012986 modification Methods 0.000 description 3
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 description 2
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- 238000005520 cutting process Methods 0.000 description 2
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- 239000010936 titanium Substances 0.000 description 2
- 238000005303 weighing Methods 0.000 description 2
- 238000003917 TEM image Methods 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
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- 230000003139 buffering effect Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000006258 conductive agent Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 239000011258 core-shell material Substances 0.000 description 1
- 238000009831 deintercalation Methods 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
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- 230000002401 inhibitory effect Effects 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
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- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical compound [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 1
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- 150000003751 zinc Chemical class 0.000 description 1
Images
Classifications
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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
- H01M4/362—Composites
- H01M4/366—Composites as layered products
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
-
- 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
-
- 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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/134—Electrodes based on metals, Si or alloys
-
- 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
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
- H01M4/386—Silicon or alloys based on silicon
-
- 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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
-
- 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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
-
- 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
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention relates to a Si@C@MOFs composite material and a preparation method thereof, a negative electrode material, a negative electrode plate and a lithium battery. According to the invention, the carbon-containing material layer is coated on the surface of the silicon compound, and the MOFs material layer is coated on the surface of the carbon-containing material layer, so that the volume expansion of silicon is favorably inhibited. In addition, the carbon-containing material provides good conductivity, and the outer MOFs material exerts the advantage of frame stability, so that the nano silicon fully exerts the advantage of capacity. In addition, the coating layer with the buffer structure is directly prepared by two-step growth and one-step carbonization, so that the reaction energy consumption is sufficiently reduced, the operation convenience is optimized, and a certain reference meaning is provided for industrialization related materials.
Description
Technical Field
The invention relates to the field of lithium ion battery anode materials, in particular to a Si@C@MOFs composite material and a preparation method thereof, an anode material, an anode piece and a lithium battery.
Background
Since the commercialization of lithium ion batteries by sony corporation in the 90 th century, the battery industry has evolved dramatically. Particularly, the lithium ion battery has the advantages of excellent cycle performance, no memory effect, high working voltage, environmental friendliness and the like, and plays an important role in the current life, and particularly, the lithium ion battery is an ideal energy source for electric automobiles and mobile equipment.
The negative electrode of the current commercial lithium ion battery is made of graphite material, and the theoretical capacity of graphite is about 372mAh/g; with the progress of technology and the improvement of requirements, the requirements of the next generation of high specific energy lithium ion batteries cannot be met. Researchers are therefore pressing to find alternative materials to graphite, where silicon (theoretical capacity of about 4200 mAh/g) has a high theoretical capacity, suitable Li insertion/extraction + The potential becomes the first choice for the negative electrode of the next generation lithium battery. However, rapid capacity decay due to the large volume expansion effect (about 300%) created when silicon is alloyed with lithium has been a barrier to silicon commercialization. Therefore, how to suppress the expansion of silicon during charge and discharge has been the main content of the study.
There are techniques for coating silicon materials with carbonization layers of MOFs to inhibit silicon expansion. However, it is difficult to obtain a negative electrode material having high capacity and excellent stability and cycle performance by coating a silicon material with only a carbonized layer of MOFs.
In addition, in the prior art, there is a technique of suppressing the charge-discharge expansion of silicon by obtaining a silicon oxide-based composite anode material by: mixing SiO, zinc salt, ferric salt, an organic ligand and an organic solvent, then placing the mixture into a chemical vapor deposition furnace, heating the mixture under the protection of inert gas, and introducing an organic carbon source for reaction after the temperature is raised to the reaction temperature; then carrying out acid treatment; and placing the sample obtained in the previous step into a chemical vapor deposition furnace, heating under the protection of inert gas, and introducing Ti source and N source gas to react after heating to the reaction temperature, thereby obtaining the silicon oxide-based composite anode material. However, the above method has the following disadvantages: the chemical vapor deposition furnace cannot be used for one-step reaction completely, the acid treatment steps are complicated in the process, the materials are required to be transferred for suction filtration and drying, and organic titanium and nitrogen sources are introduced while CVD is carried out, so that the process is slow, and the material utilization rate is not high.
Disclosure of Invention
Problems to be solved by the invention
In view of the above, there is a need to provide a negative electrode composite material which can suppress the volume expansion of silicon, has a sufficiently high capacity and is excellent in stability and cycle performance, and also a method of producing the same which is low in energy consumption, easy in production process, suppresses the volume expansion of silicon to some extent even if more silicon is possibly added, and can be produced industrially.
Solution for solving the problem
In the invention, the nano silicon is coated by a three-dimensional framework structure formed by growing a second MOFs material on the surface of the nano silicon, and the nano silicon is coated in the space of the framework of the middle layer by coating a layer of a first MOFs material on the surface of the second MOFs material and then forming an intermediate conductive carbon-containing material layer by using high-temperature carbonization treatment. The carbon-containing material provides good conductivity, the first MOFs material plays a role in frame stability, so that the nano silicon fully plays a role in high capacity, and the nano silicon provides the overall material with the characteristic of high capacity, so that the high-capacity anode material is formed. In addition, the invention also provides a preparation flow which has low energy consumption, easy preparation process and industrialized production, and the coating layer with the buffer structure is directly prepared through two-step growth and one-step carbonization. Even if more silicon may be added, the volume expansion of silicon is suppressed to some extent.
The invention provides a Si@C@MOFs composite material which is characterized by comprising a core, an intermediate layer and an outer layer, wherein the core comprises a silicon compound, the intermediate layer comprises a carbon-containing material, and the outer layer comprises a first MOFs material.
The composite material according to the above, wherein the particle size of the silicon-based compound is in the range of 1-2000nm, preferably 20-1000nm, more preferably 20-300nm.
The composite material according to the above, wherein the thickness of the carbonaceous material layer as the intermediate layer is 1 to 2000nm, preferably 10 to 1000nm; the thickness of the first MOFs layer as the outer layer is 0.001 μm to 20. Mu.m, preferably 0.01 μm to 0.5. Mu.m.
The composite material according to the above, wherein the silicon-based compound is selected from one or more of silicon, silicon oxide; preferably, the silicon compound is a negatively charged silicon compound modified by a modifier, and the modifier is one or more selected from PSS, sodium allyloxy sulfonate, sodium allyloxy hydroxy propane sulfonate and sodium n-decyl sulfate.
The composite material of the above, wherein the carbonaceous material is from a second MOFs material; the boiling point of the first MOFs material is higher than the boiling point of the second MOFs material.
The composite material according to the above, wherein the metal ions in the first MOFs material and the second MOFs material are selected from at least one of Zn, co, cu, and the organic ligand is selected from at least one of trimesic acid, terephthalic acid, and dimethylimidazole.
The invention also provides a preparation method of the composite material, which comprises the following steps:
step S1: adding a silicon compound into a carbon source solution, and stirring in a water bath to obtain a Si@ carbon source material with a carbon source coating the silicon compound;
step S2: putting the Si@ carbon source material obtained in the step S1 into an aqueous solution containing an organic ligand for forming a first MOFs material, then adding metal salt, stirring and standing to obtain a Si@ carbon source @ MOFs material of which the Si@ carbon source material is coated by the first MOFs material;
step S3: sintering the Si@ carbon source@MOFs material obtained in the step S2 to carbonize the carbon source, thereby obtaining the Si@C@MOFs composite material.
The preparation method according to the above, wherein the mass ratio of the silicon-based compound to the carbon source is 1:1 to 1:10, preferably 1:2 to 1:5; the ratio of the total mass of the Si@ carbon source material to the mass of the first MOFs material is 1:1-1:10, preferably 1:1.5-1:5.
The preparation method according to the above, further comprising step S0 before step S1: dispersing the silicon compound in a solvent, and adding a modifier to modify the silicon compound, so that the silicon compound has electronegativity.
The preparation method according to the above, wherein the modifier is selected from one or more of PSS, sodium allyloxy sulfonate, sodium allyloxy hydroxy propane sulfonate, and sodium n-decyl sulfate.
The preparation method according to the above, wherein the solvent is selected from one or more of water, ethanol, ethylene glycol, propanol.
The preparation method according to the above, wherein in the step S1, the temperature of the water bath is 1 to 100 ℃, preferably 40 to 80 ℃, and the water bath time is 1 to 24 hours, preferably 2 to 12 hours.
The preparation method according to the above, wherein the step S2 is performed at room temperature for a period of 5 to 24 hours, preferably 8 to 15 hours; the metal salt is added in one portion or in portions.
The preparation method according to the above, wherein in the step S3, the sintering temperature is 700-1500 ℃, the heating rate is 1-8 ℃/min, and the sintering time is 4-10h.
According to the preparation method, the carbon source is a second MOFs material; the carbon source solution is obtained by dissolving a metal salt for forming the second MOFs material and an organic ligand in a solvent; the boiling point of the first MOFs material is higher than the boiling point of the second MOFs material.
The preparation method according to the above, wherein the metal salt used for forming the first MOFs material and the second MOFs material is at least one selected from zinc acetate, zinc nitrate, cobalt acetate, cobalt nitrate, cobalt phosphate, copper acetate, copper nitrate, and the organic ligand used for forming the first MOFs material and the second MOFs material is at least one selected from trimesic acid, terephthalic acid, and dimethylimidazole;
preferably, the second MOFs material is selected from ZIF-8; the first MOFs material is selected from ZIF-67.
The invention also provides a negative electrode material which comprises the Si@C@MOFs composite material or the Si@C@MOFs composite material obtained by the preparation method.
The invention also provides a negative electrode plate which comprises the negative electrode material.
The invention also provides a lithium battery, which comprises the negative electrode plate.
ADVANTAGEOUS EFFECTS OF INVENTION
The technical scheme of the invention has the following beneficial effects:
(1) In the negative electrode material, the capacity advantage of the nano silicon is fully exerted through the framework structure of the first MOFs material, and the conductive network is constructed through forming the stable first MOF structure, so that the conductivity is improved.
(2) The intermediate carbonaceous material layer in the negative electrode material improves the conductivity of single silicon, thereby improving the conductivity of the whole material; the loose structure of the carbonaceous material layer provides more effective space for the nano silicon, releasing the high capacity of the silicon.
(3) The negative electrode material provided by the invention can inhibit the extremely attenuation of the battery capacity caused by structural collapse by inhibiting the excessive volume expansion of silicon, and remarkably improves the capacity compared with a conventional graphite-based negative electrode material and remarkably improves the cycle times compared with a conventional silicon-based negative electrode.
(4) The cathode material can form a more stable SEI film, reduce repeated generation of the SEI film and seriously consume electrolyte, and improve the coulomb efficiency of a battery.
(5) According to the invention, through a two-step growth and one-step carbonization preparation method, an HF etching method, a CVD chemical vapor deposition method, a protective gas burning method and the like which are used in a conventional silicon-carbon system preparation method, the reaction energy consumption is fully reduced, the operation convenience is optimized, and a certain reference significance is provided for industrialization related materials.
Drawings
FIG. 1 shows that example 1 was conducted at 0.5 A.g -1 Cycling diagram at current density.
FIG. 2 shows that example 2 is at 0.5A·g -1 Cycling diagram at current density.
Fig. 3 shows a graph of the rate performance of example 1 at different current densities.
Fig. 4 shows a plot of the rate performance of example 2 at different current densities.
FIG. 5 shows that comparative example 1 was at 0.5 A.g -1 Cycling diagram at current density.
FIG. 6 shows that comparative example 2 was at 0.5 A.g -1 Cycling diagram at current density.
Fig. 7 shows a graph of the rate performance of comparative example 1 at different current densities.
Fig. 8 shows a graph of the rate performance of comparative example 2 at different current densities.
Fig. 9 shows a transmission electron micrograph of the composite material prepared in example 1.
Detailed Description
The following describes embodiments of the present invention, but the present invention is not limited thereto. The present invention is not limited to the configurations described below, and various modifications are possible within the scope of the invention as claimed, and embodiments obtained by appropriately combining the technical means disclosed in the different embodiments and the appropriate combination examples are also included in the technical scope of the present invention. All documents described in the present specification are incorporated by reference in the present specification.
Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
In the present specification, the numerical range indicated by the term "numerical value a to numerical value B" means a range including the end point numerical value A, B.
In the present specification, unless specifically stated otherwise, "a plurality" of "a plurality of" etc. means a numerical value of 2 or more.
In this specification, the terms "substantially", "substantially" or "substantially" mean that the error is less than 5%, or less than 3%, or less than 1% as compared to the relevant perfect or theoretical standard.
In the present specification, "%" means mass% unless otherwise specified.
In the present specification, if "room temperature", "normal temperature" or the like occurs, the temperature thereof may be generally 10 to 37℃or 15 to 35 ℃.
In the present specification, the meaning of "can" or "can" includes both the meaning of the presence or absence of both, and the meaning of both the treatment and the absence of both.
In this specification, "optional" and "optionally" mean that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not.
The term "comprising" in the description of the invention and the claims and in the above figures and any variants thereof is intended to cover a non-exclusive inclusion. For example, a process, method, or system, article, or apparatus that comprises a list of steps or elements is not limited to only those listed but may optionally include additional steps or elements not listed or inherent to such process, method, article, or apparatus.
Reference throughout this specification to "some/preferred embodiments," "an embodiment," etc., means that a particular element (e.g., feature, structure, property, and/or characteristic) described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it is to be understood that the elements may be combined in any suitable manner in the various embodiments.
< first aspect >
A first aspect of the present invention relates to a si@c@mofs composite material comprising a core comprising a silicon compound, an intermediate layer comprising a carbonaceous material and an outer layer comprising a first MOFs material. Hereinafter, the core and the intermediate layer may be abbreviated as "si@c".
In the invention, the silicon compound is selected from one or more of silicon, silicon oxide and silicon oxide. In some preferred embodiments, the silicon-based compound is a negatively charged silicon-based compound modified with a modifier to facilitate uniform growth of the subsequently described second MOFs material on the surface of the silicon-based compound. In the invention, the modifier can be selected from one or more of PSS, sodium allyloxy sulfonate, sodium allyloxy hydroxy propane sulfonate, sodium n-decyl sulfate and the like.
In the present invention, the particle size of the silicon-based compound is in the range of 1 to 2000nm, preferably 20 to 1000nm, more preferably 20 to 300nm. If the grain size of the silicon compound is too large, the formed Si@C structure is unstable, and the structure of the carbon-containing material can not well inhibit the volume expansion of silicon in the charge and discharge processes; if the particle size of the silicon-based compound is too small, the cost is too high.
In some embodiments, the particle size of the silicon-based compound may be 1nm, 10nm, 20nm, 50nm, 80nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, 550nm, 600nm, 650nm, 700nm, 750nm, 800nm, 850nm, 900nm, 950nm, 1000nm, 1200nm, 1500nm, 1800nm, 2000nm, etc.
In the present invention, the mass ratio of the total mass of the silicon-based compound and the carbonaceous material to the first MOFs material may be 1:1 to 1:10, preferably 1:2 to 1:5. In some embodiments, the mass ratio of the total mass of silicon-based compounds and carbonaceous material to the first MOFs material may be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, etc. If the mass ratio is too high, the first MOFs material cannot fully cover the Si@C material, and Si@C material is easy to remain; whereas if the mass ratio is too low, the amount of the first MOFs material is too large, easy to remain, and difficult to collect the product.
In the composite material of the invention, the mass ratio of the silicon compound to the carbonaceous material can be 1:1-1:10, preferably 1:2-1:5. In some embodiments, the mass ratio of the silicon-based compound to the carbonaceous material may be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, etc. The shell formed by too much carbonaceous material is thicker, which is unfavorable for Li in the charge and discharge process + Is inserted/withdrawn from the housing; if the amount of the carbonaceous material is too small, the silicon is not inhibitedThe volume expands during the storage of lithium, thereby causing collapse of the crystal lattice.
In the present invention, the thickness of the carbonaceous material layer as the intermediate layer may be in the range of 1 to 2000nm, preferably 10 to 1000nm, and may be, for example, 1nm, 10nm, 30nm, 50nm, 80nm, 100nm, 150nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1000nm, 1200nm, 1500nm, 1800nm, 2000nm, etc., and if the thickness of the carbonaceous material layer is too thick, it is unfavorable for intercalation and deintercalation of lithium ions during charge and discharge; if the thickness of the carbonaceous material layer is too thin, volume expansion that does not survive the lithium storage process is suppressed, thereby causing collapse of the crystal lattice.
In the present invention, the thickness of the first MOFs layer as the outer layer may be 0.001 μm to 20. Mu.m, preferably 0.01 μm to 0.5. Mu.m, and may be, for example, 0.001 μm, 0.005 μm, 0.01 μm, 0.03 μm, 0.05 μm, 0.08 μm, 0.1 μm, 0.5 μm, 1 μm, 3 μm, 5 μm, 13 μm, 15 μm, 17 μm, 18 μm, 20 μm, etc. If the first MOFs layer is too thin, it is difficult to ensure uniformity of the coating layer, and if the first MOFs layer is too thick, the capacity of the material is reduced.
In the present invention, the carbonaceous material for the intermediate layer is derived from the second MOFs material. Wherein the boiling point of the first MOFs material is higher than the boiling point of the second MOFs material, such that the second MOFs material is capable of carbonizing to form a carbonaceous material without carbonizing the first MOFs material. The loose structure of the carbon-containing material layer from the second MOFs material provides more available space for nano-silicon, freeing up the high capacity of silicon. In addition, the carbon-containing material improves the conductivity of single silicon, and improves the conductivity of the whole material to a certain extent.
In the invention, the metal ions in the first MOFs material and the second MOFs material can be selected from at least one of Zn, co and Cu, and the organic ligand can be selected from at least one of trimesic acid, terephthalic acid and dimethyl imidazole. In some preferred embodiments, the metal ion for the first MOFs material may be Co and the organic ligand may be dimethylimidazole; the metal ion for the second MOFs material may be zinc and the organic ligand may be dimethylimidazole.
In the Si@C@MOFs composite material, the excessive expansion of the volume of silicon is restrained by the stress of the carbon-containing material and the stress of the first MOFs material, so that the extremely attenuation of the battery capacity caused by structural collapse due to the excessive expansion of the volume of silicon is avoided. The carbon in the middle layer provides certain conductivity, improves the conductivity of single silicon, improves the conductivity of the whole material to a certain extent, and also provides certain protection for the silicon, so that the carbon layer from the second MOFs material is loose, provides more effective space for the silicon, and releases the high capacity of the silicon. The MOFs material of the outer layer plays a role in stabilizing a frame, so that the nano silicon fully plays a role in capacity; the conductive network is constructed by forming a stable first MOF structure, thereby improving conductivity.
Compared with the conventional graphite-based negative electrode material, the negative electrode material formed by the composite material provided by the invention has the advantages that the capacity is obviously improved, and the cycle times are obviously improved, so that the negative electrode material provided by the invention has high capacity and stability. In addition, the cathode material can form a more stable SEI film, reduce repeated generation of the SEI film and seriously consume electrolyte, and improve the coulomb efficiency of the battery.
< second aspect >
A second aspect of the present invention relates to a method for producing the si@c@mofs composite material in the above < first aspect >, comprising:
step S1: adding a silicon compound into a carbon source solution, and stirring in a water bath to obtain a Si@ carbon source material with a carbon source coating the silicon compound;
step S2: putting the Si@ carbon source material obtained in the step S1 into an aqueous solution containing an organic ligand for forming a first MOFs material, then adding metal salt, stirring and standing to obtain a Si@ carbon source @ MOFs material of which the Si@ carbon source material is coated by the first MOFs material;
step S3: sintering the Si@ carbon source@MOFs material obtained in the step S2 to carbonize the carbon source, thereby obtaining the Si@C@MOFs composite material.
The silicon compound of the present aspect is the same as the silicon compound of the above < first aspect > in kind, particle diameter, and the like, and will not be described again here.
In some preferred embodiments, the preparation method of the present invention further comprises step S0 prior to step S1: dispersing a silicon compound in a solvent, and adding a modifier to modify the silicon compound, so that the silicon compound has electronegativity.
Examples of the modifier are the same as those in the above < first aspect >. The solvent used herein may be selected from one or more of water, ethanol, ethylene glycol, propanol.
In the present invention, the carbon source is a second MOFs material. The boiling point of the second MOFs material is lower than that of the first MOFs material, so that only the second MOFs material may be carbonized in step S3. Modification of the silicon-based compound to negatively charged properties facilitates uniform growth of the second MOFs material on the surface of the silicon-based compound.
The metal salt used to form the first MOFs material and the second MOFs material may be selected from at least one of zinc acetate, zinc nitrate, cobalt acetate, cobalt nitrate, cobalt phosphate, copper acetate, copper nitrate. The organic ligand used to form the first MOFs material and the second MOFs material may be selected from at least one of trimesic acid, terephthalic acid, dimethyl imidazole. In some preferred embodiments, the metal ion for the first MOFs material may be cobalt acetate, cobalt nitrate or cobalt phosphate, and the organic ligand may be dimethylimidazole; the metal ion for the second MOFs material may be zinc acetate or zinc nitrate and the organic ligand may be dimethylimidazole.
In specific embodiments, the first MOFs material or the second MOFs material may be obtained by dissolving an organic ligand in a solvent such as water or ethanol and then mixing with a metal salt, or dissolving an organic ligand and a metal salt together in a solvent such as water or ethanol.
In step S1, the mass ratio of the silicon-based compound to the carbon source may be 1:1 to 1:10, preferably 1:2 to 1:5, whereby a suitable mass ratio of the silicon-based compound to the carbonaceous material may be ensured. If the carbon source is too much, the shell is thicker, which is unfavorable for Li in the charge and discharge process + Is inserted/withdrawn from the housing; if the amount of the carbon source is too small, the volume expansion of silicon in the lithium storage process is not inhibited, and thus the collapse of the crystal lattice is caused.
In step S1, the temperature of the water bath is 1-100deg.C, preferably 40-80deg.C, and the water bath time is 1-24h, preferably 2-12h. If the water bath temperature is too low, the solvent evaporates too slowly, and if the water bath temperature is too high, the second MOFs material cannot be uniformly coated on the surface of the silicon compound.
In some embodiments of the invention, an amount of the metal salt and the organic ligand are dissolved in a solvent such as water or ethanol, and an amount of the silicon-based compound is added to form a mixed solution. The solvent was then removed by stirring in a water bath to yield Si@ second MOFs material.
In step S2, the mass ratio of the total mass of the Si@ carbon source material to the first MOFs material is controlled to be 1:1 to 1:10, preferably 1:1.5 to 1:5, whereby a suitable mass ratio of si@c to the first MOFs can be ensured. If the mass ratio is too high, the first MOFs material cannot fully cover the Si@C material, and Si@C material is easy to remain; whereas if the mass ratio is too low, the amount of the first MOFs material is too large, easy to remain, and difficult to collect the product.
In the preparation method of the invention, the step S2 is carried out at room temperature, and the standing time is 5-24 hours, preferably 8-15 hours. In step S2, the metal salt may be added in one portion or in divided portions.
In some embodiments of the present invention, the amount of Si@ carbon source material obtained in step S1 is placed in an aqueous solution of an amount of an organic ligand, and then an amount of a metal salt is added at one time or in portions and stirred and left for a period of time, thereby obtaining Si@ carbon source @ MOFs material of the first MOFs material coating the Si@ carbon source material.
In step S3, the sintering temperature (also referred to herein as "carbonization temperature") is 700 to 1500 ℃, preferably 700 to 1000 ℃, the temperature rising rate is 1 to 8 ℃ per minute, preferably 3 to 6 ℃ per minute, and the sintering time is 4 to 10 hours, preferably 5 to 8 hours. If the temperature is too low, the metal nodes in the second MOFs material cannot volatilize, and a larger expansion space cannot be provided for silicon; if the temperature is too high, the metal in the first MOFs material volatilizes.
According to the invention, the coating layer with the buffer structure is directly prepared by two-step growth and one-step carbonization, and the volume expansion of silicon can be inhibited to a certain extent even if more silicon can be added. The preparation method provided by the invention is a preparation flow which has the advantages of low energy consumption, easy preparation process and industrialized production, and compared with an HF etching method, a CVD chemical vapor deposition method, a shielding gas burning method and the like used in the conventional silicon-carbon system preparation method, the preparation method sufficiently reduces the reaction energy consumption, optimizes the operation convenience and provides a certain reference significance for industrialized related materials.
< third aspect >
The invention also provides a negative electrode material which comprises the Si@C@MOFs composite material or the Si@C@MOFs composite material obtained by the preparation method.
The invention also provides a negative electrode plate which comprises the negative electrode material.
The invention further provides a lithium battery which comprises the negative electrode plate.
Examples
The present invention will be described in detail by examples. The examples of embodiments are intended to illustrate the invention and are not to be construed as limiting the invention. The specific techniques or conditions are not identified in the examples and are performed according to techniques or conditions described in the literature in this field or according to the product specifications. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
Example 1
(1) Preparation of Si@C@MOFs composite material
Step S0: 0.1g (particle size of 20-60 nm) of nano silicon powder is weighed and dissolved in 50mL of ethanol solution, and 1mL of PSS is added; modifying the nano silicon powder, and centrifugally separating to obtain the electronegative nano silicon powder.
Step S1: dissolving 5g of zinc acetate and 5g of dimethyl imidazole in 40ml of ethanol, and adding all the nano silicon powder prepared in the step S0; and (3) placing the mixture in a water bath at 50 ℃ to stir and slowly evaporate the solvent, thereby obtaining the ZIF-8@Si core-shell structure.
Step S2: weighing 1g of ZIF-8@Si material prepared in the step S1, putting 1.12g of dimethyl imidazole water solution, adding 2g of cobalt acetate at a time, stirring and standing for 12h, and finally centrifugally drying and collecting the ZIF67@ZIF-8@Si material, wherein the mass ratio of the ZIF-8@Si material to the obtained ZIF-67 is 1:1.
Step S3: and (2) carbonizing ZIF67@ZIF-8@Si prepared in the step (S2) in a tube furnace at a carbonization temperature of 800 ℃, a heating rate of 5 ℃/min and a carbonization time of 6 hours.
(2) Preparation of negative plate and assembly of half battery
Weighing the following components in percentage by mass: 5:5, mixing the cathode material, the conductive agent SP and the adhesive PAA with a proper amount of deionized water to ensure that the solid content of the cathode slurry is 43wt%, mechanically stirring the cathode slurry on a magnetic stirrer for 12 hours, and slowly and uniformly coating the stirred slurry on a copper foil.
And (3) putting the coated copper foil into a vacuum drying oven to be dried for 12 hours at 80 ℃, taking out the copper foil the next day, and cutting the copper foil into 12mm wafers for later use by using a Shenzherake crystal cutting machine.
The negative electrode sheet was transferred into a glove box in preparation for assembly of a full cell. The 2032 battery shell, the PP diaphragm and the commercial LB315 electrolyte are used, the prepared electrode sheet is used as a negative electrode, the lithium sheet is used as a counter electrode to assemble a half battery, the assembled battery still needs to stand for 12 hours, and then an electrochemical test is carried out.
(3) Electrochemical performance test
Different technical tests were performed by a new wilt electrical tester: the method comprises the steps of charge-discharge cycle and rate performance test. The test conditions were: constant temperature and humidity at 25 ℃ and voltage range of 0.01-1.5V;
CV, EIS were tested by the Shanghai Chen Hua CHI660 electrochemical workstation. Wherein the CV test voltage range is 0.01-3V and the scanning speed is 5mV/s; the EIS test frequency is 0.01-10000HZ, and the voltage amplitude is 0.05mV. The test results are shown in table 1 below and in fig. 1 and 3.
Example 2
Except that the mass ratio of ZIF-8@Si to ZIF-67 in step S2 was changed to 1:1, si@C@MOFs composite materials were prepared under the same conditions as in example 1, and negative electrode sheets were prepared by the same steps and conditions as in example 1, and the composition of half cells and electrochemical performance test were performed. The test results are shown in table 1 below and in fig. 2 and 4.
Example 3
In this example, except that the mass ratio of ZIF-8@Si to ZIF-67 was changed to 1:5, a Si@C@MOFs composite material was prepared under the same conditions as in example 1, and a negative electrode sheet was prepared by the same procedure and conditions as in example 1, and the composition and electrochemical performance of a half cell were tested.
The battery prepared in this example has higher cycle performance and rate performance similar to those of example 1.
Example 4
The nano-silicon used in this example had a particle size of 100-200nm, and other steps and conditions were the same as in example 1, and a negative electrode tab was prepared and a half cell composition and electrochemical performance test were performed by the same steps and conditions as in example 1.
The battery prepared in this example has higher cycle performance and rate performance similar to those of example 1.
Example 5
In this example, silicon oxide was used instead of nano silicon, and other steps and conditions were the same as in example 1, and a negative electrode tab was prepared and a half cell composition and electrochemical performance test were performed by the same steps and conditions as in example 1.
The battery prepared in this example has higher cycle performance and rate performance similar to those of example 1.
Comparative example 1
1g of graphite was weighed out in place of the ZIF-8@Si material in step S2 of example 1, si@MOFs composite materials were prepared in accordance with steps S2 and S3 of example 1, and a negative electrode sheet was prepared by the same procedure and conditions as in example 1, and the composition of a half cell and electrochemical performance test were conducted. The test results are shown in table 1 below and in fig. 5 and 7.
Comparative example 2
1g of nano silicon powder was weighed out in place of the ZIF-8@Si material in step S2 in example 1, si@MOFs composite material was prepared in accordance with steps S2 and S3 in example 1, and a negative electrode sheet was prepared by the same procedure and conditions as in example 1, and the composition of a half cell and electrochemical performance test were conducted. The test results are shown in table 1 below and in fig. 6 and 8.
Table 1.0.5A g -1 Capacity retention after 100 cycles
| Examples numbering | 0.5A·g -1 Capacity retention after 100 cycles (%) |
| Example 1 | 80.17 |
| Example 2 | 53.41 |
| Comparative example 1 | 77.48 |
| Comparative example 2 | 1.48 |
The capacity retention rates of the respective examples can be seen from table 1, wherein the capacity retention rates in examples 1 and 2 are 80.17% and 53.41%. As can be seen from FIG. 1, the anode material prepared in example 1 has a higher specific capacity and cycle retention, wherein at 0.5 A.g -1 The specific capacity of the second discharge at the current density of (2) is 876.8 mAh.g -1 The specific capacity after 100 times of circulation is 703.3 mAh.g -1 The capacity retention was 80.17%. The capacity performance was far higher than that of the graphite of comparative example 1 in terms of cycle performance and specific capacity performance, as shown in FIG. 5 (the specific capacity after 100 cycles was 270.76mAh g -1 ) The cycle performance is also superior to that of the comparisonThe pure nano-silicon of example 2 is shown in fig. 6 (100 cycles of the incomplete cycle).
As can be seen from FIG. 2, the anode material prepared in example 2 has a higher specific capacity and cycle retention, wherein at 0.5Ag -1 The specific capacity of the second discharge at the current density of (2) is 790.6mAh g -1 The specific capacity after 100 times of circulation is 422.4mAh g -1 The capacity retention was 53.41%. The capacity performance was far higher than that of the graphite of comparative example 1 in terms of cycle performance and specific capacity performance, as shown in FIG. 5 (the specific capacity after 100 cycles was 270.76mAh g -1 ) The cycling performance was superior to that of the pure nano-silicon of comparative example 2, as shown in fig. 6 (100 cycles of the incomplete cycle).
As can be seen from FIG. 3, the anode material prepared in example 1 has a higher specific capacity and cycle retention, wherein at 0.1. 0.1A g -1 The specific capacity of the second discharge at the current density of (2) is 857.8mAh g -1 After experiencing 2A g -1 High current density cycle and return 0.1A g -1 At a current density of (2), the 30 th-turn discharge capacity was 790.5mAh g -1 The capacity retention was 92.15% and the specific capacity was higher than that of the graphite of comparative example 1 and the nano-silicon of comparative example 2, as shown in fig. 7 and 8, respectively. This demonstrates that the anode material of example 1 can maintain good electrochemical performance under high rate charge and discharge of the battery, and can meet the current fast charge and fast discharge requirements.
As can be seen from FIG. 4, the anode material prepared in example 2 has higher specific capacity and cycle retention, wherein the anode material has a specific capacity of 0.1Ag -1 The specific capacity of the second discharge at the current density of (2) is 782.3mAh g -1 After experiencing 2Ag -1 High current density cycling and return to 0.1Ag -1 At a current density of (2), the 30 th-turn discharge capacity was 758.6mAh g -1 The capacity retention was 96.97%, and the specific capacity was higher than that of the graphite of comparative example 1 and the nano-silicon of comparative example 2, as shown in fig. 7 and 8, respectively. This demonstrates that the anode material of example 2 can maintain good electrochemical performance under high rate charge and discharge of the battery, and can meet the current fast charge and fast discharge requirements.
Fig. 9 is a Transmission Electron Microscope (TEM) photograph of the composite material prepared in example 1. The outermost coating layer is shown to be about 40nm thick and uniformly adhered to the surface of the inner layer. The middle is nano silicon, the thickness of the middle carbon layer is about 50nm, and the coating is relatively uniform in the whole. This demonstrates the reason that examples 1, 2 have a very high capacity retention during cycling, with more buffering than nano-silicon, providing some protection.
The foregoing description of embodiments of the invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the various embodiments described. The terminology used herein was chosen in order to best explain the principles of the embodiments, the practical application, or the technical improvements in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
Industrial applicability
According to the invention, the carbon-containing material layer is coated on the surface of the silicon compound, and the MOFs material layer is coated on the surface of the carbon-containing material layer, so that the volume expansion of silicon is favorably inhibited. In addition, the carbon-containing material provides good conductivity, and the outer MOFs material exerts the advantage of frame stability, so that the nano silicon fully exerts the advantage of capacity. In addition, the coating layer with the buffer structure is directly prepared by two-step growth and one-step carbonization, so that the reaction energy consumption is sufficiently reduced, the operation convenience is optimized, and a certain reference meaning is provided for industrialization related materials.
Claims (19)
1. A si@c@mofs composite material, characterized in that the composite material comprises a core, an intermediate layer and an outer layer, the core comprising a silicon-based compound, the intermediate layer comprising a carbonaceous material, the outer layer comprising a first MOFs material.
2. The composite material according to claim 1, wherein the particle size of the silicon-based compound is in the range of 1-2000nm, preferably 20-1000nm, more preferably 20-300nm.
3. Composite according to claim 1 or 2, wherein the thickness of the layer of carbonaceous material as intermediate layer is 1-2000nm, preferably 10-1000 nm; the thickness of the first MOFs layer as the outer layer is 0.001 μm to 20. Mu.m, preferably 0.01 μm to 0.5. Mu.m.
4. A composite material according to any one of claims 1 to 3, wherein the silicon-based compound is selected from one or more of silicon, silicon oxide; preferably, the silicon compound is a negatively charged silicon compound modified by a modifier, and the modifier is one or more selected from PSS, sodium allyloxy sulfonate, sodium allyloxy hydroxy propane sulfonate and sodium n-decyl sulfate.
5. The composite material of any one of claims 1-4, wherein the carbonaceous material is from a second MOFs material; the boiling point of the first MOFs material is higher than the boiling point of the second MOFs material.
6. The composite material of claim 5, wherein the metal ions in the first and second MOFs materials are selected from at least one of Zn, co, cu, and the organic ligand is selected from at least one of trimesic acid, terephthalic acid, and dimethylimidazole.
7. A method of preparing a composite material, the method comprising:
step S1: adding a silicon compound into a carbon source solution, and stirring in a water bath to obtain a Si@ carbon source material with a carbon source coating the silicon compound;
step S2: putting the Si@ carbon source material obtained in the step S1 into an aqueous solution containing an organic ligand for forming a first MOFs material, then adding metal salt, stirring and standing to obtain a Si@ carbon source @ MOFs material of which the Si@ carbon source material is coated by the first MOFs material;
step S3: sintering the Si@ carbon source@MOFs material obtained in the step S2 to carbonize the carbon source, thereby obtaining the Si@C@MOFs composite material.
8. The production method according to claim 7, wherein the mass ratio of the silicon-based compound to the carbon source is 1:1 to 1:10, preferably 1:2 to 1:5; the ratio of the total mass of the Si@ carbon source material to the mass of the first MOFs material is 1:1-1:10, preferably 1:1.5-1:5.
9. The production method according to claim 7 or 8, further comprising step S0 before step S1: dispersing the silicon compound in a solvent, and adding a modifier to modify the silicon compound, so that the silicon compound has electronegativity.
10. The method of claim 9, wherein the modifier is selected from one or more of PSS, sodium allyloxy sulfonate, sodium allyloxy hydroxy propane sulfonate, sodium n-decyl sulfate.
11. The production method according to claim 9 or 10, wherein the solvent is selected from one or more of water, ethanol, ethylene glycol, propanol.
12. The preparation method according to any one of claims 7-11, wherein in step S1 the water bath is at a temperature of 1-100 ℃, preferably 40-80 ℃, for a water bath time of 1-24h, preferably 2-12h.
13. The preparation method according to any one of claims 7-12, wherein said step S2 is performed at room temperature for a period of 5-24 hours, preferably 8-15 hours; the metal salt is added in one portion or in portions.
14. The production method according to any one of claims 7 to 13, wherein in the step S3, the sintering temperature is 700 to 1500 ℃, the temperature rising rate is 1 ℃/min to 8 ℃/min, and the sintering time is 4 to 10 hours.
15. The method of any one of claims 7-14, wherein the carbon source is a second MOFs material; the carbon source solution is obtained by dissolving a metal salt for forming the second MOFs material and an organic ligand in a solvent; the boiling point of the first MOFs material is higher than the boiling point of the second MOFs material.
16. The production method according to claim 15, wherein the metal salt used for forming the first MOFs material and the second MOFs material is at least one selected from zinc acetate, zinc nitrate, cobalt acetate, cobalt nitrate, cobalt phosphate, copper acetate, copper nitrate, and the organic ligand used for forming the first MOFs material and the second MOFs material is at least one selected from trimesic acid, terephthalic acid, and dimethylimidazole;
preferably, the second MOFs material is selected from ZIF-8; the first MOFs material is selected from ZIF-67.
17. A negative electrode material, characterized in that it comprises the si@c@mofs composite material according to any one of claims 1 to 6 or the si@c@mofs composite material obtained by the production method according to any one of claims 7 to 16.
18. A negative electrode sheet comprising the negative electrode material of claim 17.
19. A lithium battery comprising the negative electrode tab of claim 18.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109216693A (en) * | 2018-09-18 | 2019-01-15 | 江西中汽瑞华新能源科技有限公司 | A kind of preparation method of lithium ion battery silicon-carbon cathode material |
| CN109671928A (en) * | 2018-12-12 | 2019-04-23 | 福建翔丰华新能源材料有限公司 | A kind of silicon based anode material and preparation method thereof of MOFs carbonization cladding |
| CN112366301A (en) * | 2020-11-11 | 2021-02-12 | 宁夏博尔特科技有限公司 | Silicon/silicon oxide/carbon composite negative electrode material for lithium ion battery and preparation method thereof |
| CN115020670A (en) * | 2022-06-30 | 2022-09-06 | 合肥国轩高科动力能源有限公司 | MOFs modified silicon-based negative electrode material and preparation method thereof |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109216693A (en) * | 2018-09-18 | 2019-01-15 | 江西中汽瑞华新能源科技有限公司 | A kind of preparation method of lithium ion battery silicon-carbon cathode material |
| CN109671928A (en) * | 2018-12-12 | 2019-04-23 | 福建翔丰华新能源材料有限公司 | A kind of silicon based anode material and preparation method thereof of MOFs carbonization cladding |
| CN112366301A (en) * | 2020-11-11 | 2021-02-12 | 宁夏博尔特科技有限公司 | Silicon/silicon oxide/carbon composite negative electrode material for lithium ion battery and preparation method thereof |
| CN115020670A (en) * | 2022-06-30 | 2022-09-06 | 合肥国轩高科动力能源有限公司 | MOFs modified silicon-based negative electrode material and preparation method thereof |
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