CN113471419A - Silicon-carbon composite material and preparation method and application thereof - Google Patents
Silicon-carbon composite material and preparation method and application thereof Download PDFInfo
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- CN113471419A CN113471419A CN202110645634.2A CN202110645634A CN113471419A CN 113471419 A CN113471419 A CN 113471419A CN 202110645634 A CN202110645634 A CN 202110645634A CN 113471419 A CN113471419 A CN 113471419A
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- 239000002153 silicon-carbon composite material Substances 0.000 title claims abstract description 38
- 238000002360 preparation method Methods 0.000 title claims abstract description 13
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 127
- 239000011856 silicon-based particle Substances 0.000 claims abstract description 38
- 238000000034 method Methods 0.000 claims abstract description 26
- 239000007773 negative electrode material Substances 0.000 claims abstract description 20
- 239000011148 porous material Substances 0.000 claims abstract description 10
- 239000002245 particle Substances 0.000 claims description 19
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical group [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims description 15
- 229910001416 lithium ion Inorganic materials 0.000 claims description 15
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 claims description 13
- 239000005011 phenolic resin Substances 0.000 claims description 13
- 229920001568 phenolic resin Polymers 0.000 claims description 13
- 239000000463 material Substances 0.000 claims description 11
- 238000000151 deposition Methods 0.000 claims description 9
- 238000007740 vapor deposition Methods 0.000 claims description 9
- 239000004005 microsphere Substances 0.000 claims description 8
- 239000002994 raw material Substances 0.000 claims description 7
- 230000008021 deposition Effects 0.000 claims description 6
- 239000003792 electrolyte Substances 0.000 claims description 6
- 229910007245 Si2Cl6 Inorganic materials 0.000 claims description 2
- 229910007264 Si2H6 Inorganic materials 0.000 claims description 2
- 229910005096 Si3H8 Inorganic materials 0.000 claims description 2
- 229910003910 SiCl4 Inorganic materials 0.000 claims description 2
- 229910003818 SiH2Cl2 Inorganic materials 0.000 claims description 2
- 229910003828 SiH3 Inorganic materials 0.000 claims description 2
- 229910003822 SiHCl3 Inorganic materials 0.000 claims description 2
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 claims description 2
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 claims description 2
- PZPGRFITIJYNEJ-UHFFFAOYSA-N disilane Chemical compound [SiH3][SiH3] PZPGRFITIJYNEJ-UHFFFAOYSA-N 0.000 claims description 2
- FDNAPBUWERUEDA-UHFFFAOYSA-N silicon tetrachloride Chemical compound Cl[Si](Cl)(Cl)Cl FDNAPBUWERUEDA-UHFFFAOYSA-N 0.000 claims description 2
- 229910001415 sodium ion Inorganic materials 0.000 claims description 2
- LXEXBJXDGVGRAR-UHFFFAOYSA-N trichloro(trichlorosilyl)silane Chemical compound Cl[Si](Cl)(Cl)[Si](Cl)(Cl)Cl LXEXBJXDGVGRAR-UHFFFAOYSA-N 0.000 claims description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 abstract description 22
- 229910052710 silicon Inorganic materials 0.000 abstract description 22
- 239000010703 silicon Substances 0.000 abstract description 22
- 230000008569 process Effects 0.000 abstract description 10
- 230000008602 contraction Effects 0.000 abstract description 6
- 230000015556 catabolic process Effects 0.000 abstract description 5
- 230000008859 change Effects 0.000 abstract description 5
- 238000006731 degradation reaction Methods 0.000 abstract description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 36
- 229910052757 nitrogen Inorganic materials 0.000 description 18
- 229910052799 carbon Inorganic materials 0.000 description 15
- 229910002804 graphite Inorganic materials 0.000 description 12
- 239000010439 graphite Substances 0.000 description 12
- 238000007599 discharging Methods 0.000 description 9
- 238000004146 energy storage Methods 0.000 description 9
- 239000005543 nano-size silicon particle Substances 0.000 description 8
- 239000010410 layer Substances 0.000 description 7
- 239000000203 mixture Substances 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 6
- 238000001816 cooling Methods 0.000 description 6
- 239000007789 gas Substances 0.000 description 6
- 239000011248 coating agent Substances 0.000 description 5
- 238000000576 coating method Methods 0.000 description 5
- 125000004122 cyclic group Chemical group 0.000 description 5
- 239000002002 slurry Substances 0.000 description 5
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- 230000014759 maintenance of location Effects 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 description 3
- 229910003481 amorphous carbon Inorganic materials 0.000 description 3
- 239000011247 coating layer Substances 0.000 description 3
- 239000002131 composite material Substances 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000011868 silicon-carbon composite negative electrode material Substances 0.000 description 3
- 230000002776 aggregation Effects 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 239000002041 carbon nanotube Substances 0.000 description 2
- 229910021393 carbon nanotube Inorganic materials 0.000 description 2
- 239000011258 core-shell material Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 239000007770 graphite material Substances 0.000 description 2
- 238000009776 industrial production Methods 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 239000002243 precursor Substances 0.000 description 2
- 239000002210 silicon-based material Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 238000010998 test method Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910032387 LiCoO2 Inorganic materials 0.000 description 1
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 239000013543 active substance Substances 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 238000010000 carbonizing Methods 0.000 description 1
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- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 1
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 239000011246 composite particle Substances 0.000 description 1
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- 239000000428 dust Substances 0.000 description 1
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- 239000008151 electrolyte solution Substances 0.000 description 1
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- 230000004927 fusion Effects 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000007731 hot pressing Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- -1 polyethylene Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 229920001187 thermosetting polymer Polymers 0.000 description 1
- 238000001291 vacuum drying 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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
-
- 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
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Composite Materials (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention discloses a silicon-carbon composite material and a preparation method and application thereof. In the charging process of the secondary battery, when the silicon particles deposited in the pores of the activated carbon expand, enough space is provided around the silicon particles to accommodate the expanded silicon particles, so that the change of the electrode thickness caused by the expansion or contraction of the silicon is greatly inhibited, and the occurrence of electrode degradation problems such as the falling of a negative electrode material is reduced.
Description
Technical Field
The invention belongs to the field of negative electrode materials of lithium ion secondary batteries, and particularly relates to a silicon-carbon composite material, a preparation method of the silicon-carbon composite material and application of the silicon-carbon composite material in the negative electrode materials of the lithium ion secondary batteries.
Background
The lithium ion secondary battery has the characteristics of high energy storage ratio, high safety, low cost, easiness in large-scale production and the like, and is widely applied as a power supply of a smart phone, an electric automobile and an energy storage system. The negative electrode material of the lithium ion secondary battery which is currently industrialized is mainly graphite material, and with the extensive research on the secondary battery in recent years, the energy storage capacity of the lithium ion secondary battery which takes graphite as the main negative electrode material is greatly improved. The theoretical energy storage ratio of graphite is 372mAh/g, and although the prior battery technology is close to the limit energy storage ratio of the graphite cathode, the requirements of miniaturized intelligent equipment and electric automobiles on secondary batteries with high energy storage ratio and high output power are still difficult to meet.
In order to solve the problem, researchers introduce an element with higher lithium ion energy storage efficiency into the existing graphite negative electrode as a solution, wherein silicon has the advantages of high lithium ion energy storage efficiency (theoretical capacity of 4200Amh/g), easy obtainment and the like, and has great attraction as a negative electrode material of a novel secondary battery.
The silicon particles expand and contract greatly during the storage and release of lithium ions (the literature reports that the volume of silicon increases by more than 3 times after lithium ions are adsorbed). After repeated charging and discharging, the silicon particles which are continuously expanded and contracted are gradually cracked, so that the silicon particles are further fragmented and react with the electrolyte to consume the electrolyte in the battery. In addition, the negative electrode particles are particularly likely to fall off from the electrode by breaking the bond of the binder due to the stress generated by the change in the thickness of the electrode caused by the expansion and contraction of the silicon particles. At present, the expansion and contraction of silicon causes the degradation of battery electrodes and the severe capacity fading, so that the practical requirements are temporarily difficult to achieve.
In order to solve the above problems, researchers have proposed various proposals for suppressing the volume expansion of the silicon material and further improving the structural stability of the silicon material, such as a silicon-carbon composite material in which silicon particles are coated between carbon matrix materials to form a core-shell structure.
CN2013103597397 mentions that a silicon-carbon composite negative electrode material sequentially comprises nano silicon/graphite particles, a first carbon coating layer and an organic cracking carbon layer structure from inside to outside, wherein the nano silicon/graphite particles are formed by coating a nano silicon particle layer with graphite as an inner core of a volume expansion buffer substrate to form spherical or spheroidal composite particles; the first carbon coating layer is a carbon nano tube and/or amorphous carbon, the carbon nano tube and/or amorphous carbon is inserted into a gap network formed among the nano silicon particles and/or coated outside the nano silicon particles, and the ionic conductivity of the material is improved; and the organic cracking carbon layer is an outermost coating layer of the silicon-carbon composite negative electrode material. The silicon-carbon composite negative electrode material improves the cycle performance and the charge and discharge performance of the battery to a certain extent, but still cannot thoroughly inhibit the overall expansion of the electrode caused by the expansion of silicon element, and the preparation process is extremely complex, the quantity of the silicon element which can be embedded is not large, the capacity of the battery cannot be greatly improved, and the large-scale industrial production is difficult to carry out.
The chinese patent CN103326023A discloses a silicon-based composite negative electrode material, which is an embedded composite core-shell structure, wherein the core is a structure formed by embedding nano-silicon particles in the inner layer gap of hollow graphite, and the shell is a non-graphite carbon material. According to the invention, the nano silicon particles are embedded in the graphite inner layer and the surface of the graphite particles is uniformly coated by adopting a mode of combining mechanical grinding, mechanical fusion, isotropic pressure treatment and a carbon coating technology. Although the cycle performance and the first efficiency of the battery are improved to a certain extent, the material still cannot inhibit the overall expansion of the electrode due to the expansion of the silicon particles, and the amount of the silicon particles which can be embedded is not large, so that the capacity of the battery cannot be greatly improved. In addition, the preparation method is also extremely complex, the cost is high, and large-scale industrial production cannot be realized.
Chinese invention patent CN103078092A mentions a preparation method of a silicon-carbon (Si/C) composite cathode material of a lithium ion battery, in the invention, a silicon source (before or after etching treatment) and graphite are dispersed in a solvent under the condition that a second additive exists, and a precursor solid is obtained after the solvent is completely volatilized by controlling the temperature; and coating the precursor solid with amorphous carbon. The nano silicon prepared by etching has large specific surface and is difficult to be uniformly dispersed on the graphite surface, so that the silicon-carbon material prepared by the method has serious silicon agglomeration and cannot solve the problem of poor cycle performance of the material caused by the expansion of silicon.
Disclosure of Invention
In order to solve the above technical problems, the first invention of the present application aims to provide a microspherical silicon carbon composite material.
The second invention of the present application is to provide a method for preparing the microspherical silicon-carbon composite material.
A third object of the present invention is to provide a negative electrode material containing the microspherical silicon carbon composite material.
A fourth object of the present invention is to provide a secondary battery containing the negative electrode material.
The technical scheme of the invention is as follows:
a silicon carbon composite comprising activated carbon and silicon particles deposited on the inner and outer surfaces of the pores of the activated carbon.
According to the present invention, the deposition rate of the silicon particles is 1.0 to 70%, more preferably 10 to 70%. When the battery is charged and discharged circularly, firstly, because the silicon particles are excessively filled, the volume expansion of the silicon does not have enough space to accommodate, and therefore strong internal stress is generated in the expansion process to damage electrode particles; secondly, when excessive silicon is deposited, the adhesion of silicon deposited on the outer surface of the microsphere is greatly increased, and the silicon in the part also expands and contracts in the charge and discharge processes, so that the electrode is deteriorated.
According to the invention, the activated carbon is microspherical.
According to the invention, the activated carbon comprises pores with the pore diameter of 0.1-50nm, including micropores 0.1-2nm and mesopores 2-50nm, and also has macropores more than 50 nm; the content of mesopores is 5% by volume or more, more preferably 10% by volume or more, and still more preferably 15% by volume or more. When the content of the mesoporous silicon particles, which is used as a deposition space for the main silicon particles, is too low, the amount of silicon particles that can be introduced is limited, and the introduction of the silicon particles requires a longer time, resulting in a low production efficiency. If the content of macropores is too large, local aggregation of a large amount of silicon is likely to occur, and the aggregated portion is likely to expand and contract during cyclic charge and discharge to cause cracking, thereby shortening the life of the electrode; preferably, the volume content of the macropores is less than 10%, preferably less than 5%.
According to the invention, the activated carbon has an average particle size of 10 μm or less, preferably a particle size of 0.1 to 10 μm, preferably 0.1 to 5 μm. When the active carbon with the particle size of more than 10 microns is selected as a raw material and silicon particles are introduced into the active carbon by adopting a vapor deposition method and then used as a negative electrode material, the thickness of the prepared electrode is thicker, and in the charging and discharging process of the battery, the path of lithium ions reaching the central part of the active carbon particles through pores of the active carbon is too long, so that the rapid and high-current charging and discharging performance is reduced.
According to the invention, the specific surface area of the activated carbon is 500-3000m2Per g, preferably 800-2(ii) in terms of/g. When the specific surface area is too small, as a carrier of silicon particles, sufficient space cannot be provided for depositing silicon, so that the energy storage property is not remarkably improved; when the specific surface area is too large, the strength of the activated carbon microspheres used as a carrier is easily low, and the activated carbon particles are damaged in the vapor deposition of silicon and the specific application process.
According to the invention, the activated carbon has a sphericity of 0.5 or more, preferably 0.7 or more, for example 0.5, 0.6, 0.7, 0.8, 0.9, 1.
According to the invention, the raw material of the activated carbon is microspherical phenolic resin.
According to the present invention, the source of the silicon particles includes, but is not limited to, SiH4，Si2H6，Si3H8，SiCl4，SiHCl3，Si2Cl6，SiH2Cl2，SiH3One or more of Cl.
According to the invention, the silicon particles are of nanometric size.
The invention also provides a preparation method of the silicon-carbon composite material, which comprises the following steps: and depositing silicon particles in the activated carbon by adopting a vapor deposition method to prepare the silicon-carbon composite material.
According to the invention, the mass ratio of the silicon particles to the activated carbon is 1: 10-1, preferably 1: 5-1, and more preferably 1.72: 1.
According to the present invention, the vapor deposition method may employ vapor deposition equipment such as a rotary furnace, a fluidized bed, etc.
According to the invention, the temperature in the furnace during deposition is 400-1200 ℃; the deposition time is determined according to the amount of silicon deposited required. For example, the furnace temperature is 400 ℃, 500 ℃, 600 ℃, 800 ℃, 1000 ℃, 1200 ℃.
According to the invention, the specific preparation method of the silicon-carbon composite material comprises the following steps: the raw material of the active carbon is carbonized at high temperature under the inert gas environment to form the active carbon with a porous structure, and then silicon particles are deposited in the active carbon by adopting a vapor deposition method to prepare the silicon-carbon composite material.
The method can be used for preparing the activated carbon with different particle sizes, and can be used for the working procedures of carbonizing, crushing, finely crushing, classifying after activation and the like of the raw materials of the activated carbon.
The preparation of the activated carbon adopts the method commonly used in the prior art, for example, the activated carbon raw material (such as thermosetting phenolic resin) is dissolved in water or organic solvent, and then is atomized, dried, carbonized and activated to obtain the activated carbon.
The silicon-carbon composite material has the advantages that in the charging and discharging process of the secondary battery, when silicon particles deposited in active carbon pores expand, enough space is reserved around the silicon particles after expansion, so that the change of the electrode thickness caused by silicon expansion and contraction is greatly inhibited, and the problem of electrode degradation caused by falling of a negative electrode material due to the change of the electrode thickness is solved.
The application also provides a negative electrode material which contains the silicon-carbon composite material.
According to the invention, the negative electrode material contains more than 5 wt% of silicon-carbon composite material, preferably more than 15 wt%.
The invention also provides application of the anode material to a secondary battery.
According to the invention, the secondary battery comprises a positive pole piece, a negative pole piece, a diaphragm and electrolyte, wherein the diaphragm and the electrolyte are arranged between the positive pole piece and the negative pole piece, and the negative pole piece comprises a negative current collector and a negative material arranged on the negative current collector.
Preferably, the secondary battery is a lithium ion battery or a sodium ion battery.
Advantageous effects
(1) Through the sieve mesh effect of the pores of the activated carbon, silicon particles are uniformly distributed to the micropores (below 2 nm), mesopores (2-50nm) and macropores (above 50nm) of the activated carbon in a nanoscale size by a vapor deposition method, so that silicon-carbon compounding is realized.
(2) In the charging process of the secondary battery, when the silicon particles deposited in the pores of the activated carbon expand, enough space is provided around the silicon particles to accommodate the expanded silicon particles, so that the change of the electrode thickness caused by the expansion or contraction of the silicon is greatly inhibited, and the occurrence of electrode degradation problems such as the falling of a negative electrode material is reduced.
(3) Compared with the common irregularly-shaped activated carbon particles, the microspherical activated carbon has the advantages of minimum external surface area and smooth and uniform particle surface due to the symmetrical spherical shape, and when silicon particles are introduced into the activated carbon by adopting a vapor deposition method and then used as a negative electrode material, the compacted density per unit volume is high, the particles are in close contact, and the electrical conductivity of the electrode material can be greatly improved. In addition, compared with irregularly-shaped activated carbon, the microspherical activated carbon has small surface area, so that the prepared battery has high initial charging and discharging efficiency, and when lithium ions reach the center of particles through the activated carbon in the charging and discharging processes of the battery, the path length is uniform, so that the charging and discharging speed is stable.
In addition, the microspherical activated carbon has smooth, edge-angle-free and uniform surfaces, so that the risk that the optimal performance of the electrode cannot be exerted due to the fact that particles are mutually rubbed, collided and broken to generate new surfaces and a large amount of nano-scale fine dust in the transportation and use processes can be effectively reduced.
(4) The secondary battery of the present invention has characteristics of large capacity, excellent cyclic chargeability (capacity retention rate is 95% or more after 100 cycles of charge and discharge), excellent coulombic efficiency (coulombic efficiency is 99% or more after 100 cycles of charge and discharge), extremely low electrode thickness expansion rate (electrode thickness expansion rate is 5% or less after 100 cycles of charge and discharge), and the like.
(5) The preparation process is simple and convenient to operate.
Detailed Description
The technical solution of the present invention will be further described in detail with reference to specific embodiments. It is to be understood that the following examples are only illustrative and explanatory of the present invention and should not be construed as limiting the scope of the present invention. All the technologies realized based on the above-mentioned contents of the present invention are covered in the protection scope of the present invention.
Unless otherwise indicated, the raw materials and reagents used in the following examples are all commercially available products or can be prepared by known methods.
Example 1
100g of microspherical phenolic resin-based activated carbon (the source of the microspherical phenolic resin-based activated carbon is PF-7001, a new material Limited company of Jinzhi Fangzheng, Jinan, D50 is 3 microns, and the specific surface area is 600m2The macroporous content is less than 5 percent, the mesoporous volume content is 11 percent, the sphericity is 0.8, the mixture is put into a rotary furnace, the temperature is increased to 500 ℃ at the speed of 5 ℃/min under the protection of 1.0L/min high-purity nitrogen, the mixture is kept for 2 hours, and then the high-purity nitrogen is switched to high-purity SiH4And keeping the gas at the flow rate of 2L/min for 1 hour, switching to high-purity nitrogen protection, and naturally cooling to room temperature to obtain 105g of silicon-carbon composite microspheres.
Example 2
100g of microspherical phenolic resin-based activated carbon (the source of the microspherical phenolic resin-based activated carbon is PF-7001, a new material Limited company of Jinzhi Fangzheng, Jinan, D50 is 3 microns, and the specific surface area is 1800m2The volume content of the mesopores is 20 percent, the volume content of the macropores is less than 5 percent, the sphericity is 0.8, the mixture is put into a rotary furnace, the temperature is increased to 500 ℃ at the speed of 5 ℃/min under the protection of 1.0L/min high-purity nitrogen, the mixture is kept for 2 hours, and then the high-purity nitrogen is switched to high-purity SiH4And keeping the gas at the flow rate of 2L/min for 2 hours, switching to high-purity nitrogen protection, and naturally cooling to room temperature to obtain 112g of silicon-carbon composite microspheres.
Example 3
100g of microspherical phenolic resin-based activated carbon (the source of the microspherical phenolic resin-based activated carbon is PF-7001, a new material Limited company of Jinzhi Fangzheng, Jinan, D50 is 3 microns, and the specific surface area is 1940m2(ii) a mesoporous volume content of 26% and a macropore volumeContent less than 5%, sphericity 0.8) is put into a rotary furnace, the temperature is raised to 500 ℃ at the speed of 5 ℃/min under the protection of 1.0L/min high-purity nitrogen, and after 2 hours of maintenance, the high-purity nitrogen is switched to high-purity SiH4And keeping the gas at the flow rate of 2L/min for 3 hours, switching to high-purity nitrogen protection, and naturally cooling to room temperature to obtain 124g of silicon-carbon composite microspheres.
Example 4
100g of microspherical phenolic resin-based activated carbon (the source of the microspherical phenolic resin-based activated carbon is PF-7001, a new material Limited company of Jinzhi Fangzheng, Jinan, D50 is 3 microns, and the specific surface area is 2230m2The mesoporous volume content is 37 percent, the macroporous volume content is less than 5 percent, the sphericity is 0.8) is put into a rotary furnace, the temperature is raised to 500 ℃ at the speed of 5 ℃/min under the protection of 1.0L/min high-purity nitrogen, the high-purity nitrogen is switched to high-purity SiH after being kept for 2 hours4And keeping the gas at the flow rate of 2L/min for 3 hours, switching to high-purity nitrogen protection, and naturally cooling to room temperature to obtain 140g of silicon-carbon composite microspheres.
Comparative example 1
100g of amorphous activated carbon (D50 ═ 5 μm, specific surface area 1820 m)2The volume content of the macropores is less than 5 percent, the volume content of the mesopores is 10 percent, and the active carbon particles are irregularly amorphous) is put into a rotary furnace, the temperature is raised to 500 ℃ at the speed of 5 ℃/min under the protection of 1.0L/min high-purity nitrogen, the temperature is kept for 2 hours, and then the high-purity nitrogen is switched to high-purity SiH4And keeping the gas at the flow rate of 2L/min for 3 hours, switching to high-purity nitrogen protection, and naturally cooling to room temperature to obtain 126g of the silicon-carbon composite material.
Comparative example 2
100g of microspherical phenolic resin-based activated carbon (the source of the microspherical phenolic resin-based activated carbon is PF-7001, a new material Limited company of Jinzhi Fangzheng, Jinan, D50 is 3 microns, and the specific surface area is 400m2/g, the volume content of the macropores is less than 5 percent, the volume content of the mesopores is 3 percent, and the sphericity is 0.8), putting the mixture into a rotary furnace, heating the mixture to 500 ℃ at the speed of 5 ℃/min under the protection of 1.0L/min high-purity nitrogen, keeping the temperature for 2 hours, and then switching the high-purity nitrogen into high-purity SiH4The gas is maintained at a flow rate of 2L/min for 1 hour and then switched back to high-purity nitrogen protection, and naturalAfter cooling to room temperature, 102g of silicon-carbon composite microspheres were prepared.
Application examples 1 to 6
The silicon-carbon composite materials prepared in examples 1-4 and comparative examples 1-2 were used for preparing negative electrode plates, and the negative electrode plates were prepared by the following methods:
90g of the silicon-carbon composite materials prepared in the examples 1 to 4 and the comparative examples 1 to 2 are taken, 5g of the conductive aid, 2.5g of carboxymethyl cellulose with solid content and 2.5g of SBR with solid content are added, a proper amount of pure water is added to adjust the slurry to proper viscosity, and then the slurry is placed into a rotation and revolution mixer to be mixed to prepare the negative electrode material.
The negative pole slurry is uniformly coated on copper foil with the thickness of 20 microns, the coating thickness is 150 microns, and the negative pole piece is prepared after hot pressing and vacuum drying.
In consideration of capacity balance of the positive and negative pole pieces, the same positive pole piece is used for the evaluation, the capacity ratio of the positive pole piece to the negative pole piece is set to be 1.2, and the weight of the active substance required by the negative pole piece is calculated according to the actual measurement capacity of the positive pole piece.
The negative electrode plate or the negative electrode material prepared by using the silicon-carbon composite materials in the embodiments 1 to 4 and the comparative examples 1 to 2 is used for preparing the lithium ion battery, and the obtained battery is respectively marked as application examples 1 to 6 (the embodiments 1 to 4 correspond to the application examples 1 to 4 in sequence, and the comparative examples 1 to 2 correspond to the application examples 5 to 6 in sequence).
The same positive pole piece is adopted in all the application examples 1 to 6, and the preparation method of the positive pole piece comprises the following steps:
90g LiCoO25g of conductive carbon black SUPER C45 and 5g of PVDF as a binder are mixed with a proper amount of N-methyl pyrrolidone, and the mixture is fully stirred and mixed to prepare the slurry for the positive electrode.
Uniformly coating the slurry on an aluminum foil with the thickness of 20 microns, and drying to obtain a positive pole piece, wherein the density of the positive pole piece is 3.6g/cm3。
Isolation film
In application examples 1 to 6, the polyethylene material diaphragm with the total thickness of 20 microns is adopted.
Electrolyte solution
In application examples 1 to 6, EC was used: EMC: DMC 1:2:2 (volume ratio) was used as an electrolyte.
The following test methods or calculation methods were used for the cyclic charge and discharge test, the electrode layer thickness expansion rate test, the capacity retention rate, and the coulombic efficiency of the batteries prepared in application examples 1 to 6. Meanwhile, the silicon content in the silicon-carbon composite materials in application examples 1 to 6 was tested. The test method or the calculation method specifically comprises the following steps:
(1) and (3) cyclic charge and discharge test: after the constant current of 100mA/g is charged to 4.2V, the constant current of 100mA/g is discharged to 3.0V.
(2) Electrode layer thickness expansion rate: (D2-D1)/D1 x 100
D1 initial electrode thickness
D2, SOC is 100% after charging and discharging for 100 times, electrode thickness after storing at 85 ℃ for 4 hours
(3) Capacity retention rate:
capacity maintenance ratio (%) after 100 cycles (100 th capacity/first capacity 100)
(4) Coulombic efficiency: discharge/charge capacity 100
(5) The silicon content (i.e., the deposition rate of silicon particles) test is determined by high frequency combustion infrared absorption.
The specific test experimental data are shown in table 1:
TABLE 1
Analysis of the data in table 1 shows that the battery prepared from the silicon-carbon composite material has the characteristics of large capacity, excellent cyclic chargeability (the capacity retention rate is more than 95% after 100 cycles of charge and discharge), excellent coulombic efficiency (the coulombic efficiency is more than 99% after 100 cycles of charge and discharge), extremely low electrode thickness expansion rate (the electrode thickness expansion rate is less than 5% after 100 cycles of charge and discharge), and the like.
The invention effectively solves the fatal defects of the prior silicon-carbon composite electrode, such as over-quick electrode degradation, shortened battery life and the like caused by the expansion and contraction of silicon particles in the charging and discharging processes.
The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A silicon carbon composite comprising activated carbon and silicon particles deposited on the inner and outer surfaces of the pores of the activated carbon.
2. Silicon carbon composite according to claim 1, characterized in that the deposition rate of the silicon particles is 1.0-70%, more preferably 10-70%.
Preferably, the activated carbon is in the form of microspheres.
Preferably, the raw material of the activated carbon is microspherical phenolic resin.
3. The silicon-carbon composite material according to any one of claims 1 to 2, wherein the activated carbon has a pore size of 0.1 to 50nm, including micropores of 0.1 to 2nm, mesopores of 2 to 50nm, and macropores of 50nm or more.
The content of mesopores is preferably 5% by volume or more, more preferably 10% by volume or more, and still more preferably 15% by volume or more.
Preferably, the volume content of the macropores is less than 10%, preferably less than 5%.
4. Silicon-carbon composite according to any of claims 1 to 3, characterized in that the activated carbon has an average particle size of 10 μm or less, preferably a particle size of 0.1 to 10 μm, preferably 0.1 to 5 μm.
Preferably, the specific surface area of the activated carbon is 500-3000m2(ii) in terms of/g. Preferably 800-2/g。
Preferably, the activated carbon has a sphericity of 0.5 or more, preferably 0.7 or more.
Preferably, the source of the silicon particles includes, but is not limited to, SiH4，Si2H6，Si3H8，SiCl4，SiHCl3，Si2Cl6，SiH2Cl2，SiH3One or more of Cl.
5. The method for preparing a silicon-carbon composite material according to any one of claims 1 to 4, wherein the method comprises: and depositing silicon particles in the activated carbon by adopting a vapor deposition method to prepare the silicon-carbon composite material.
6. The preparation method according to claim 5, wherein the mass ratio of the silicon particles to the activated carbon is 1:10 to 1, preferably 1:5 to 1.
7. The negative electrode material is characterized by containing the silicon-carbon composite material.
Preferably, the negative electrode material contains 5 wt% or more of a silicon-carbon composite material, preferably 15 wt% or more.
8. Use of the negative electrode material according to claim 7 in a secondary battery.
9. The use of claim 8, wherein the secondary battery comprises a positive electrode plate, a negative electrode plate, a separator disposed between the positive electrode plate and the negative electrode plate, and an electrolyte; the negative pole piece comprises a negative pole current collector and a negative pole material arranged on the negative pole current collector.
10. Use according to claim 8, wherein the secondary battery is a lithium ion battery or a sodium ion battery.
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| WO2023245652A1 (en) * | 2022-06-24 | 2023-12-28 | 上海杉杉科技有限公司 | Spherical silicon-based lithium storage material and preparation method therefor |
| WO2024044963A1 (en) * | 2022-08-30 | 2024-03-07 | 宁德新能源科技有限公司 | Negative electrode sheet, secondary battery, and electronic device |
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| WO2023245652A1 (en) * | 2022-06-24 | 2023-12-28 | 上海杉杉科技有限公司 | Spherical silicon-based lithium storage material and preparation method therefor |
| WO2024044963A1 (en) * | 2022-08-30 | 2024-03-07 | 宁德新能源科技有限公司 | Negative electrode sheet, secondary battery, and electronic device |
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