CN116995200A - Multi-element doped porous silicon core-shell composite material and preparation method and application thereof - Google Patents
Multi-element doped porous silicon core-shell composite material and preparation method and application thereof Download PDFInfo
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- CN116995200A CN116995200A CN202310734366.0A CN202310734366A CN116995200A CN 116995200 A CN116995200 A CN 116995200A CN 202310734366 A CN202310734366 A CN 202310734366A CN 116995200 A CN116995200 A CN 116995200A
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- 239000002131 composite material Substances 0.000 title claims abstract description 51
- 239000011258 core-shell material Substances 0.000 title claims abstract description 24
- 229910021426 porous silicon Inorganic materials 0.000 title claims abstract description 22
- 238000002360 preparation method Methods 0.000 title claims abstract description 18
- 239000005543 nano-size silicon particle Substances 0.000 claims abstract description 59
- 238000000034 method Methods 0.000 claims abstract description 31
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims abstract description 27
- 239000000395 magnesium oxide Substances 0.000 claims abstract description 21
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims abstract description 19
- 229910052749 magnesium Inorganic materials 0.000 claims abstract description 18
- 239000011777 magnesium Substances 0.000 claims abstract description 18
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims abstract description 15
- 239000003054 catalyst Substances 0.000 claims abstract description 13
- 238000007740 vapor deposition Methods 0.000 claims abstract description 12
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims abstract description 10
- 229910003481 amorphous carbon Inorganic materials 0.000 claims abstract description 10
- 229910052796 boron Inorganic materials 0.000 claims abstract description 10
- 238000001027 hydrothermal synthesis Methods 0.000 claims abstract description 10
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims abstract description 9
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 9
- 239000011574 phosphorus Substances 0.000 claims abstract description 9
- 238000000151 deposition Methods 0.000 claims abstract description 3
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical group F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 26
- 229940091250 magnesium supplement Drugs 0.000 claims description 17
- 239000007789 gas Substances 0.000 claims description 16
- 239000011261 inert gas Substances 0.000 claims description 13
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical group [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 12
- VZGDMQKNWNREIO-UHFFFAOYSA-N tetrachloromethane Chemical compound ClC(Cl)(Cl)Cl VZGDMQKNWNREIO-UHFFFAOYSA-N 0.000 claims description 12
- 238000010438 heat treatment Methods 0.000 claims description 11
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 10
- FFBGYFUYJVKRNV-UHFFFAOYSA-N boranylidynephosphane Chemical compound P#B FFBGYFUYJVKRNV-UHFFFAOYSA-N 0.000 claims description 10
- 239000002904 solvent Substances 0.000 claims description 9
- 229910052799 carbon Inorganic materials 0.000 claims description 8
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 8
- 238000006243 chemical reaction Methods 0.000 claims description 7
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- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical group O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 6
- 238000005530 etching Methods 0.000 claims description 6
- 239000002153 silicon-carbon composite material Substances 0.000 claims description 6
- 239000010405 anode material Substances 0.000 claims description 5
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 claims description 4
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims description 4
- 239000005977 Ethylene Substances 0.000 claims description 4
- 239000002253 acid Substances 0.000 claims description 4
- CDQSJQSWAWPGKG-UHFFFAOYSA-N butane-1,1-diol Chemical compound CCCC(O)O CDQSJQSWAWPGKG-UHFFFAOYSA-N 0.000 claims description 4
- DMBHHRLKUKUOEG-UHFFFAOYSA-N diphenylamine Chemical compound C=1C=CC=CC=1NC1=CC=CC=C1 DMBHHRLKUKUOEG-UHFFFAOYSA-N 0.000 claims description 4
- 238000001035 drying Methods 0.000 claims description 4
- 238000004321 preservation Methods 0.000 claims description 4
- 229910021578 Iron(III) chloride Inorganic materials 0.000 claims description 3
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 claims description 3
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 claims description 3
- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 claims description 3
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 claims description 3
- 229960005336 magnesium citrate Drugs 0.000 claims description 3
- 235000002538 magnesium citrate Nutrition 0.000 claims description 3
- 239000004337 magnesium citrate Substances 0.000 claims description 3
- CRGZYKWWYNQGEC-UHFFFAOYSA-N magnesium;methanolate Chemical compound [Mg+2].[O-]C.[O-]C CRGZYKWWYNQGEC-UHFFFAOYSA-N 0.000 claims description 3
- PLSARIKBYIPYPF-UHFFFAOYSA-H trimagnesium dicitrate Chemical compound [Mg+2].[Mg+2].[Mg+2].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O.[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O PLSARIKBYIPYPF-UHFFFAOYSA-H 0.000 claims description 3
- 239000008096 xylene Substances 0.000 claims description 3
- RVDLHGSZWAELAU-UHFFFAOYSA-N 5-tert-butylthiophene-2-carbonyl chloride Chemical compound CC(C)(C)C1=CC=C(C(Cl)=O)S1 RVDLHGSZWAELAU-UHFFFAOYSA-N 0.000 claims description 2
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 claims description 2
- 229910021586 Nickel(II) chloride Inorganic materials 0.000 claims description 2
- QHUNZUWQAIPCAS-UHFFFAOYSA-N [P].[Mg].[B] Chemical compound [P].[Mg].[B] QHUNZUWQAIPCAS-UHFFFAOYSA-N 0.000 claims description 2
- 239000012298 atmosphere Substances 0.000 claims description 2
- GVPFVAHMJGGAJG-UHFFFAOYSA-L cobalt dichloride Chemical compound [Cl-].[Cl-].[Co+2] GVPFVAHMJGGAJG-UHFFFAOYSA-L 0.000 claims description 2
- QMMRZOWCJAIUJA-UHFFFAOYSA-L nickel dichloride Chemical compound Cl[Ni]Cl QMMRZOWCJAIUJA-UHFFFAOYSA-L 0.000 claims description 2
- 239000000377 silicon dioxide Substances 0.000 claims 2
- 125000002734 organomagnesium group Chemical group 0.000 claims 1
- 239000011248 coating agent Substances 0.000 abstract description 4
- 238000000576 coating method Methods 0.000 abstract description 4
- 238000010306 acid treatment Methods 0.000 abstract description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 20
- 238000012360 testing method Methods 0.000 description 20
- 239000011162 core material Substances 0.000 description 18
- 239000000463 material Substances 0.000 description 14
- 230000000052 comparative effect Effects 0.000 description 11
- 229910052786 argon Inorganic materials 0.000 description 10
- 239000003792 electrolyte Substances 0.000 description 10
- 229910052710 silicon Inorganic materials 0.000 description 9
- 239000007788 liquid Substances 0.000 description 8
- 239000010703 silicon Substances 0.000 description 8
- 238000010521 absorption reaction Methods 0.000 description 7
- 229910052744 lithium Inorganic materials 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 5
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 5
- 229910001416 lithium ion Inorganic materials 0.000 description 5
- 230000014759 maintenance of location Effects 0.000 description 5
- 238000001291 vacuum drying Methods 0.000 description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 239000010410 layer Substances 0.000 description 4
- -1 magnesium ethoxide cyclohexane Chemical compound 0.000 description 4
- 239000007773 negative electrode material Substances 0.000 description 4
- 238000007781 pre-processing Methods 0.000 description 4
- 239000008367 deionised water Substances 0.000 description 3
- 229910021641 deionized water Inorganic materials 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
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- 239000004033 plastic Substances 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 101150058243 Lipf gene Proteins 0.000 description 2
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 2
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- 239000003575 carbonaceous material Substances 0.000 description 2
- 238000005253 cladding Methods 0.000 description 2
- 239000011247 coating layer Substances 0.000 description 2
- 239000006258 conductive agent Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 239000008187 granular material Substances 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 229910052814 silicon oxide Inorganic materials 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910013870 LiPF 6 Inorganic materials 0.000 description 1
- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 description 1
- ORUCDOXAKFCOJF-UHFFFAOYSA-N [O-2].[Mg+2].[Li+] Chemical compound [O-2].[Mg+2].[Li+] ORUCDOXAKFCOJF-UHFFFAOYSA-N 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 239000013543 active substance Substances 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
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- 230000009286 beneficial effect Effects 0.000 description 1
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- 238000005229 chemical vapour deposition Methods 0.000 description 1
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- 239000007772 electrode material Substances 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
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- 229910052751 metal Inorganic materials 0.000 description 1
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- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 150000003376 silicon Chemical class 0.000 description 1
- 239000011856 silicon-based particle Substances 0.000 description 1
- 239000011870 silicon-carbon composite anode material Substances 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 238000012876 topography Methods 0.000 description 1
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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- 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
- H01M4/364—Composites as mixtures
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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
- H01M4/38—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
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
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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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
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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
- H01M2004/021—Physical characteristics, e.g. porosity, surface area
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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
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/027—Negative electrodes
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- Chemical Kinetics & Catalysis (AREA)
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- General Chemical & Material Sciences (AREA)
- Composite Materials (AREA)
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- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The embodiment of the invention discloses a multi-element doped porous silicon core-shell composite material, wherein the inner core of the composite material is magnesium oxide doped nano silicon, the outer shell is phosphorus element and boron element doped amorphous carbon, and the mass percentage of the outer shell is 1-10wt% based on the total weight of the composite material as 100%. The preparation process comprises the following steps: firstly, carrying out acid treatment on nano silicon, then carrying out magnesium oxide doping by carrying out hydrothermal reaction with a solution containing organic magnesium and a catalyst, and finally, depositing amorphous carbon, phosphorus and boron on the outer layer by a vapor deposition method. The composite material has higher power and first charge and discharge efficiency through multi-layer doping of multiple elements, amorphous carbon, phosphorus and boron elements are sequentially deposited on the surface of the core, the stability of the core structure and the integrity of the coating are improved, and the impedance is further reduced and the first efficiency is improved by means of doping of the elements.
Description
Technical Field
The invention belongs to the field of lithium ion battery materials, and particularly relates to a multi-element doped porous silicon core-shell composite material, and a preparation method and application thereof.
Background
Silicon is of great interest due to its high theoretical specific capacity and low lithium intercalation potential. Li and Si can form an alloy Li 4.4 Si has a theoretical specific capacity of up to 4200mAh/g, but silicon has a large volume effect (up to 300%) in the process of alloying with lithium, resulting in collapse of an electrode structure and peeling of an active material, so that the electrode material loses electrical contact, capacity is rapidly attenuated, and the conductivity of the silicon is poor, thereby seriously impeding the practical application of pure-phase silicon as a negative electrode material of a lithium ion battery. Silicon in the silicon-carbon composite anode material is used as an active substance to provide lithium storage capacity; the carbon serves as a dispersion matrix to buffer the volume change of the silicon particles when lithium is intercalated and deintercalated, maintain the structural integrity of the electrode, and maintain the electrical contact inside the electrode. Therefore, the silicon-carbon composite material combines the advantages of the two materials, has high specific capacity and long cycle life, and is expected to replace graphite to become a new generation of lithium ion battery anode material.
However, the silicon-carbon composite material also has the defects that the power performance is influenced by poor electronic conductivity and the energy density of the full battery is influenced by low efficiency for the first time. One of the measures to increase the power and first efficiency of the material is doping, cladding and alloying of the material. For example, patent number CN111048770B discloses a ternary doped silicon-based composite material, a preparation method and application thereof, the composite anode material comprises silicon, silicon oxide, dopant, silicate and carbon coating layers, the silicate and doped element oxide are uniformly distributed in the silicon oxide substrate to form a uniform composite structure, the carbon material coating layer is uniformly coated on the surface of the composite structure, the first efficiency and the cycle performance of the material are improved, the first doped element and the second doped element are physically mixed, the consistency is poor, the binding force between the materials is poor, and the multiplying power and the expansion performance of the material are not improved.
Disclosure of Invention
In order to solve the defects in the prior art, the invention provides the multi-element doped porous silicon core-shell composite material, and the power performance, the first efficiency and the expansion resistance of the silicon-carbon material are improved through the doping of multiple elements and the change of a combination mode between materials.
In order to achieve the technical purpose, the invention adopts the following technical scheme:
the technical purpose of the first aspect of the invention is to provide a multi-element doped porous silicon core-shell composite material, wherein the inner core of the multi-element doped porous silicon core-shell composite material is magnesium oxide doped nano silicon, the outer shell of the multi-element doped porous silicon core-shell composite material is phosphorus element and boron element doped amorphous carbon, and the mass percentage of the outer shell is 1-10wt% based on the total weight of the composite material as 100%.
Further, the mass percentage of magnesium oxide in the inner core is 1-10wt% based on the total weight of the inner core as 100%.
Further, based on 100% of the total weight of the shell, the mass percentage of phosphorus in the shell is 1.5-4.5wt% and the mass percentage of boron is 0.5-1.5wt%.
Further, the particle size of the multi-element doped porous silicon core-shell composite material is 2-20 mu m.
The technical purpose of the second aspect of the invention is to provide a preparation method of a multi-element doped porous silicon core-shell composite material, which comprises the following steps:
pretreatment of nano silicon: carrying out surface etching treatment on the nano silicon by adopting acid steam to obtain porous nano silicon;
preparation of the core: adding porous nano silicon into a solution containing organic magnesium and a catalyst, dispersing, performing hydrothermal reaction in a high-pressure reaction kettle, and drying to obtain a magnesium oxide doped nano silicon core; wherein the organic magnesium is at least one selected from magnesium citrate, magnesium ethoxide and magnesium methoxide; the catalyst is at least one of ferric chloride, cobalt chloride and nickel chloride;
preparation of the shell: and (3) introducing carbon source gas into a container for placing the inner core in an inert atmosphere by adopting a vapor deposition method, heating to react, depositing an amorphous carbon layer on the surface of the inner core, and introducing boron phosphide gas to react to obtain the multi-element doped porous silicon core-shell composite material.
Further, in the pretreatment process of the nano silicon, the acid vapor is hydrofluoric acid vapor. The specific process of carrying out surface etching treatment on the nano silicon is as follows: at the temperature of 50-100 ℃, hydrofluoric acid steam is used for contacting with nano silicon, and etching treatment is carried out for 1-3h.
Further, in the process of preparing the kernel, the organic magnesium and the catalyst are respectively dissolved in a solvent and then mixed, and then the porous nano silicon is added; the organic magnesium solvent is at least one selected from carbon tetrachloride, cyclohexane, N-methyl pyrrolidone, xylene, ethylene glycol and butanediol; the mass concentration of the organic magnesium in the solution is 1-10wt%. The solvent of the catalyst is at least one of carbon tetrachloride, cyclohexane, diphenylamine, butanediol and N-methyl pyrrolidone, and the mass concentration of the catalyst in the solution is 0.5-5wt%.
Further, when preparing the inner core, the porous nano silicon, the organic magnesium and the catalyst are mixed according to the mass ratio of 100:0.5-2:0.1-1.
Further, when preparing the kernel, the temperature of the hydrothermal reaction is 100-200 ℃, the pressure is 1-5Mpa, and the reaction is 1-6h.
Further, in preparing the core, the drying is vacuum drying at 60-100 ℃ for 8-36 hours.
Further, in the preparation of the shell, the specific operation process of the vapor deposition method is as follows: the inner core is placed in a tube furnace, inert gas is firstly introduced to discharge air in the tube furnace, carbon source gas is introduced, then the temperature is raised to 700-1000 ℃ for heat preservation for 1-6 hours, then the temperature is heated to 1000-1300 ℃, boron phosphide gas is introduced and heat preservation is carried out for 1-6 hours, and then inert gas is introduced and the temperature is reduced, so that the magnesium-boron-phosphorus co-doped silicon-carbon composite material is obtained.
Further, the carbon source gas used in the vapor deposition method is selected from at least one of methane, ethane, acetylene, and ethylene.
The technical purpose of the third aspect of the invention is to provide the application of the multi-element doped porous silicon core-shell composite material as the battery anode material.
The implementation of the embodiment of the invention has the following beneficial effects:
(1) The multi-element doped porous silicon core-shell composite material comprises a nano silicon surface doped magnesia inner core and a phosphorus element and boron element doped amorphous carbon outer shell, wherein the multi-element multi-layer doping improves the power and the first efficiency performance of the material;
(2) According to the invention, firstly, through acid treatment, the surface of the nano silicon is made to be porous, the specific surface area of the nano silicon is increased, and the expansion resistance of the nano silicon is enhanced; secondly, in the preparation process of the kernel, organic magnesium is used as a raw material in a hydrothermal reaction mode, so that magnesium is doped on the surface of the nano silicon in a magnesium oxide mode, the doping uniformity is good, and the magnesium oxide is connected with a silicon matrix in a chemical bond mode, so that the preparation method has the advantages of reducing the impedance of a composite material and improving the power performance compared with other element doping modes; and amorphous carbon, phosphorus and boron elements are sequentially deposited on the surface of the magnesia doped nano silicon kernel by a vapor deposition method, so that the stability of the kernel structure and the integrity of cladding can be improved, and the impedance is further reduced and the first efficiency is improved by means of doping of the elements. The nano silicon is doped with magnesium by a hydrothermal method, and the method has the advantages of good uniformity, mild reaction conditions of organic magnesium and the like.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Wherein:
fig. 1 is an SEM image of the multi-element doped porous silicon core-shell composite material prepared in example 1.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In examples 1-3 a multi-element doped porous silicon core-shell composite was prepared:
example 1
S1, preprocessing nano silicon: heating hydrofluoric acid to 80 ℃ to form hydrofluoric acid steam, then introducing the hydrofluoric acid steam into a plastic vessel containing nano silicon, preserving heat for 2 hours, and then washing with deionized water to obtain porous nano silicon with etched surface;
s2, preparing a kernel: adding 100g of porous nano silicon into 20mL of carbon tetrachloride solution of 5wt% magnesium citrate, uniformly mixing and dispersing the mixture with 50mL of carbon tetrachloride solution of 1wt% ferric chloride, transferring the mixture into a high-pressure reaction kettle, performing hydrothermal reaction for 3h at 150 ℃ and 3Mpa pressure, filtering, and vacuum drying filter residues at 80 ℃ for 24h to obtain a magnesium oxide doped nano silicon inner core;
s3, preparing a shell: transferring the inner core of the magnesium oxide doped nano silicon into a tube furnace, adopting a vapor deposition method, firstly introducing argon inert gas to discharge the air in the tube, introducing methane gas (the flow is 50 mL/min), heating to 900 ℃, preserving heat for 3 hours, then heating to 1200 ℃, introducing boron phosphide gas, preserving heat for 3 hours, then introducing argon inert gas, and cooling to room temperature to obtain the multi-element doped porous silicon core-shell composite material.
Example 2
S1, preprocessing nano silicon: heating hydrofluoric acid to 50 ℃ to form hydrofluoric acid steam, then introducing the hydrofluoric acid steam into a plastic vessel containing nano silicon, preserving heat for 3 hours, and then washing with deionized water to obtain porous nano silicon with etched surface;
s2, preparing a kernel: adding 100g of porous nano silicon into 100mL of 0.5wt% magnesium ethoxide cyclohexane solution, uniformly mixing and dispersing the mixture with 100mL of 0.1wt% cobalt chloride cyclohexane solution, transferring the mixture into a high-pressure reaction kettle, carrying out hydrothermal reaction for 6h at the temperature of 100 ℃ and the pressure of 5Mpa, filtering, and vacuum drying filter residues at the temperature of 80 ℃ for 24h to obtain a magnesium oxide doped nano silicon core;
s3, preparing a shell: transferring the inner core of the magnesium oxide doped nano silicon into a tube furnace, adopting a vapor deposition method, firstly introducing argon inert gas to discharge the air in the tube, introducing acetylene gas (flow 10 mL/min) to heat up to 1000 ℃ for 1h, then heating to 1300 ℃, introducing boron phosphide for 1h, then introducing argon inert gas, and cooling to room temperature to obtain the multi-element doped porous silicon core-shell composite material.
Example 3
S1, preprocessing nano silicon: heating hydrofluoric acid to 100 ℃ to form hydrofluoric acid steam, then introducing the hydrofluoric acid steam into a plastic vessel containing nano silicon, preserving heat for 1h, and then washing with deionized water to obtain porous nano silicon with etched surface;
s2, preparing a kernel: adding 100g of porous nano silicon into 20mL of 10wt% magnesium methoxide xylene solution, uniformly dispersing the solution and 20mL of 5wt% nickel chloride diphenylamine solution, transferring the solution into a high-pressure reaction kettle, carrying out hydrothermal reaction for 1h at the temperature of 200 ℃ and the pressure of 1Mpa, filtering, and vacuum drying filter residues at the temperature of 80 ℃ for 24h to obtain a magnesium oxide doped nano silicon inner core;
s3, preparing a shell: transferring 100g of the inner core of the magnesia doped nano silicon into a tube furnace, adopting a vapor deposition method, firstly introducing argon inert gas into a discharge tube, introducing ethylene gas (the flow is 100 mL/min), heating to 700 ℃, preserving heat for 6 hours, then heating to 1000 ℃, introducing boron phosphide, preserving heat for 6 hours, then introducing argon inert gas, and cooling to room temperature to obtain the multi-element doped porous silicon core-shell composite material.
Comparative example 1
100g of nano silicon and 2g of magnesium powder are added into 500mL of ethanol, uniformly mixed by a ball mill, then transferred into a tube furnace, and subjected to chemical vapor deposition, firstly, air in an argon inert gas discharge tube is introduced, ethylene gas (with the flow of 100 mL/min) is introduced, the temperature is raised to 700 ℃ and kept for 6 hours, and then, the temperature is reduced to room temperature under the argon atmosphere, so that the silicon-carbon composite material is obtained.
Comparative example 2
The procedure of example 1 was followed except that the pretreatment of S1 for nano-silicon was not performed, to obtain a composite material.
Comparative example 3
S1, carrying out the pretreatment process of nano silicon, wherein the pretreatment process is the same as the step S1 in the embodiment 1, and obtaining the porous nano silicon with etched surface;
s2, preparing a kernel: adding 100g of porous nano silicon and 0.26g of magnesia powder into 500mL of ethanol, and uniformly mixing by a ball mill to obtain a magnesia physically doped nano silicon core;
s3, preparing a shell: the core prepared in the step S2 is adopted, and other operation processes are the same as the step S3 of the embodiment 1, so that the composite material is obtained.
Comparative example 4
S1, preprocessing nano silicon: step S1 in example 1;
s2, preparing a kernel: step S2 as in example 1;
s3, preparing a shell: transferring the inner core of the magnesia doped nano silicon into a tube furnace, adopting a vapor deposition method, firstly introducing argon inert gas into a discharge tube of air, introducing methane gas (the flow is 50 mL/min), heating to 900 ℃, preserving heat for 3 hours, then introducing the argon inert gas, and cooling to room temperature to obtain the composite material.
Performance testing of the materials prepared in the above examples and comparative examples:
(1) Topography testing
SEM test was performed on the multi-element doped porous silicon core-shell composite material prepared in example 1, and the test results are shown in fig. 1. As can be seen from FIG. 1, the composite material has a granular structure with slight bonding between the granules, and the granule size is between 5 and 15 μm.
(2) Physical and chemical performance test
The composite materials prepared in examples 1-3 and comparative examples 1-4 were tested for tap density and specific surface area according to the method of national standard GBT-24533-2019 "graphite negative electrode materials for lithium ion batteries", and the powder conductivity was tested by a four-probe tester. The test results are shown in Table 1.
TABLE 1
(3) Button cell testing
The composite materials in examples 1-3 and comparative examples 1-4 are used as negative electrode materials of lithium ion batteries to be assembled into button batteries, and the specific preparation method of the negative electrode materials is as follows: adding binder, conductive agent and solvent into the composite material, stirring to slurry, coating on copper foil, oven drying, and rolling. The adhesive is LA132 adhesive, the conductive agent SP, the solvent is NMP, and the composite material comprises the following components: SP: LA132: nmp=95 g:1g:4g:220mL, preparing a negative electrode plate; a metal lithium sheet is used as a counter electrode; the electrolyte adopts LiPF 6 EC+DEC, liPF in electrolyte 6 The electrolyte is a mixture of EC and DEC with the volume ratio of 1:1, and the concentration of the electrolyte is 1.3mol/L; the diaphragm adopts a polypropylene PP film. The button cell assembly was performed in an argon filled glove box. Electrochemical performance was carried out on a wuhan blue electric CT2001A type battery tester with a charge-discharge voltage ranging from 0.00V to 2.0V and a charge-discharge rate of 0.1C, and the first discharge capacity and first efficiency of the button cell were tested, and the test results are shown in table 2.
TABLE 2
As can be seen from tables 1 and 2, the specific capacity and the first efficiency of the composite materials prepared in the examples of the present invention are significantly better than those of the comparative examples. The reasons for this may be: the primary efficiency is improved by doping magnesium into the nano silicon to form lithium magnesium oxide in the charge and discharge process, and meanwhile, the shell is coated with boron phosphide, so that on one hand, the probability of direct contact between the nano silicon and electrolyte is reduced, the occurrence of side reaction is reduced, and the primary efficiency is improved; meanwhile, boron phosphide has higher specific capacity than amorphous carbon, and can improve the specific capacity of the material. Meanwhile, the coating material boron phosphide has the characteristic of high tap density, and the tap density of the anode material is improved.
(3) Soft package battery test:
the composite materials of examples 1 to 3 and comparative examples 1 to 4 were mixed with 90% of artificial graphite, respectively, as an estimated material to prepare a negative electrodeA sheet made of NCM532 as a positive electrode material; liPF in electrolyte 6 As electrolyte, a mixture of EC and DEC in a volume ratio of 1:1 is used as a solvent; a5 Ah soft package battery was prepared using Celgard 2400 membrane as a separator.
a. Liquid absorption capacity test
And (3) a 1mL burette is adopted to absorb the electrolyte VmL, a drop is dripped on the surface of the pole piece, timing is carried out until the electrolyte is absorbed, the time t is recorded, and the liquid absorption speed V/t of the pole piece is calculated. The test results are shown in Table 3.
b. Liquid retention rate test
Calculating theoretical liquid absorption m of the pole piece according to the pole piece parameters 1 And weigh the weight m of the pole piece 2 Then the pole piece is placed into electrolyte to be soaked for 24 hours, and the weight of the pole piece is weighed to be m 3 Calculating the liquid absorption m of the pole piece 3 -m 2 And calculated according to the following formula: retention = (m) 3 -m 2 )*100％/m 1 . The test results are shown in Table 3.
TABLE 3 Table 3
As can be seen from Table 3, the liquid absorption and retention capacities of the silicon composites obtained in examples 1-3 are significantly higher than those of the comparative examples. Experimental results show that the silicon-carbon composite material has higher liquid absorption and retention capacity. The reasons for this may be: the specific surface of the composite material is larger, and the liquid absorption and retention capacity of the material is improved.
c. Pole piece rebound rate test
Firstly, testing the average thickness D1 of the pole piece by adopting a thickness gauge, then placing the pole piece in a vacuum drying oven at 80 ℃ for drying for 48 hours, testing the thickness D2 of the pole piece, and calculating according to the following formula: rebound rate= (D2-D1) ×100%/D1. The test results are shown in Table 4.
d. Pole piece resistivity test
The resistivity of the pole pieces was measured using a resistivity tester and the test results are shown in table 4.
TABLE 4 Table 4
As can be seen from the data in table 4, the negative electrode sheet prepared by the composite material of the present invention has significantly lower rebound rate and resistivity than the negative electrode sheet prepared by the composite material of the present invention. The reasons for this may be: the multi-layer coating in the shell can bind the expansion of the core material in the charge-discharge process and the rolling process, thereby reducing the rebound of the pole piece.
e. Cycle performance test
The cycle performance of the battery was tested at 25.+ -. 3 ℃ with a charge/discharge rate of 1C/1C and a voltage range of 2.8V-4.2V. The test results are shown in Table 5.
F. Quick charge performance
Constant current+constant voltage charging was performed at a rate of 3C up to a voltage of 4.2V, and a constant current ratio=constant current capacity/(constant current capacity+constant voltage capacity) was calculated. The test results are shown in Table 5.
TABLE 5
As can be seen from table 5, the cycle performance and the fast charge performance (constant current ratio) of the battery prepared from the composite material prepared by the embodiment of the invention are obviously superior to those of the comparative example, and the reason is probably that the pole piece prepared from the composite material has a lower expansion rate, the structure of the pole piece is more stable in the charge and discharge process, and the cycle performance of the pole piece is improved; in addition, the low-impedance elements of the multi-layer doped magnesium and boron reduce impedance and improve the constant current ratio of the battery.
The foregoing disclosure is illustrative of the present invention and is not to be construed as limiting the scope of the invention, which is defined by the appended claims.
Claims (10)
1. A multi-element doped porous silicon core-shell composite material is characterized in that the core is magnesium oxide doped nano silicon, the shell is phosphorus element and boron element doped amorphous carbon, and the mass percentage of the shell is 1-10wt% based on the total weight of the composite material being 100%.
2. The porous silica core-shell composite material according to claim 1, wherein the mass percentage of magnesium oxide in the core is 1 to 10wt% based on 100% of the total weight of the core.
3. The porous silica core-shell composite material according to claim 1, wherein the mass percentage of phosphorus in the shell is 1.5-4.5wt% and the mass percentage of boron is 0.5-1.5wt% based on 100% of the total weight of the shell.
4. The method for preparing the multi-element doped porous silicon core-shell composite material of claim 1, comprising the following steps:
pretreatment of nano silicon: carrying out surface etching treatment on the nano silicon by adopting acid steam to obtain porous nano silicon;
preparation of the core: adding porous nano silicon into a solution containing organic magnesium and a catalyst, dispersing, performing hydrothermal reaction in a high-pressure reaction kettle, and drying to obtain a magnesium oxide doped nano silicon core; wherein the organic magnesium is at least one selected from magnesium citrate, magnesium ethoxide and magnesium methoxide; the catalyst is at least one of ferric chloride, cobalt chloride and nickel chloride;
preparation of the shell: and (3) introducing carbon source gas into a container for placing the inner core in an inert atmosphere by adopting a vapor deposition method, heating to react, depositing an amorphous carbon layer on the surface of the inner core, and introducing boron phosphide gas to react to obtain the multi-element doped porous silicon core-shell composite material.
5. The method according to claim 4, wherein in the pretreatment of nano-silicon, the acid vapor is hydrofluoric acid vapor; the specific process of carrying out surface etching treatment on the nano silicon is as follows: at the temperature of 50-100 ℃, hydrofluoric acid steam is used for contacting with nano silicon, and etching treatment is carried out for 1-3h.
6. The preparation method according to claim 4, wherein during the preparation of the core, the organomagnesium and the catalyst are dissolved in the solvent respectively and then mixed, and then the porous nano-silicon is added; the organic magnesium solvent is at least one selected from carbon tetrachloride, cyclohexane, N-methyl pyrrolidone, xylene, ethylene glycol and butanediol; the mass concentration of the organic magnesium in the solution is 1-10wt%; the solvent of the catalyst is at least one of carbon tetrachloride, cyclohexane, diphenylamine, butanediol and N-methyl pyrrolidone, and the mass concentration of the catalyst in the solution is 0.5-5wt%; the porous nano silicon, the organic magnesium and the catalyst are mixed according to the mass ratio of 100:0.5-2:0.1-1.
7. The preparation method according to claim 4, wherein the hydrothermal reaction is carried out at a temperature of 100-200 ℃ and a pressure of 1-5Mpa for 1-6 hours when preparing the core.
8. The method according to claim 4, wherein the specific operation of the vapor deposition method is as follows: the inner core is placed in a tube furnace, inert gas is firstly introduced to discharge air in the tube furnace, carbon source gas is introduced, then the temperature is raised to 700-1000 ℃ for heat preservation for 1-6 hours, then the temperature is heated to 1000-1300 ℃, boron phosphide gas is introduced and heat preservation is carried out for 1-6 hours, and then inert gas is introduced and the temperature is reduced, so that the magnesium-boron-phosphorus co-doped silicon-carbon composite material is obtained.
9. The method according to claim 4, wherein the carbon source gas used in the vapor deposition method is at least one selected from the group consisting of methane, ethane, acetylene and ethylene.
10. Use of the composite material of claim 1 or the composite material prepared by the preparation method of claim 4 as a battery anode material.
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| CN118387879B (en) * | 2024-06-20 | 2024-09-13 | 深圳索理德新材料科技有限公司 | Multielement doped silicon-carbon composite material, preparation method thereof and lithium ion battery |
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