CN110474025A - A kind of multi-stage buffering structure silicon-carbon cathode material and its preparation method and application - Google Patents

A kind of multi-stage buffering structure silicon-carbon cathode material and its preparation method and application Download PDF

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CN110474025A
CN110474025A CN201810447992.0A CN201810447992A CN110474025A CN 110474025 A CN110474025 A CN 110474025A CN 201810447992 A CN201810447992 A CN 201810447992A CN 110474025 A CN110474025 A CN 110474025A
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silicon
carbon cathode
carbon
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cathode material
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陈旭
曲宗凯
杨文胜
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Beijing University of Chemical Technology
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Beijing University of Chemical Technology
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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
    • 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
    • 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
    • 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
    • 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
    • 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 present invention provides a kind of preparation methods of lithium ion battery silicon-carbon composite material, the silicon-carbon cathode material is by the hybrid shaping according to a certain percentage of nano-structure porous silicon, graphite, pitch, final products are obtained after calcining, wherein Si-C composite material is the microballoon with multi-stage buffering structure.The nano-structure porous silicon is obtained by magnesiothermic reduction diatomite with nanosizing is sanded, and is dispersed in inside silicon-carbon complex microsphere, wherein the partial size of silicon is less than 200 nm and there is one layer of uniform clad on surface.The silicon-carbon cathode material is high-efficient for lithium ion battery, capacity is big, good cycling stability, and the preparation method of silicon-carbon cathode material is simple, at low cost, is suitble to large-scale production.

Description

A kind of multi-stage buffering structure silicon-carbon cathode material and its preparation method and application
Technical field
The present invention relates to a kind of multi-stage buffering structure silicon-carbon cathode material, and preparation method thereof and it is negative as lithium ion battery The application of pole material.
Background technique
Due to lithium ion battery have pollution-free, long service life, it is small in size, can be quickly charged and discharged outstanding advantages of, Through being widely used in portable electronic device and electric car.In recent years, battery energy density is required with people It increasingly improves, the material system of current battery is not able to satisfy high-energy density requirement gradually.For negative electrode material, graphite Class negative electrode material has been widely used in commercial Li-ion battery, but the theoretical capacity of graphite negative electrodes material is only 372mAh/g can no longer meet the demand for development of lithium ion battery small-size light-weight, driving for a long time.Therefore novel bear is developed Pole material system is always the emphasis and hot spot researched and developed.
Silicon based anode material is due to being following most promising bear with high specific capacity and low removal lithium embedded current potential One of pole material system.However silicon generates huge volume change during removal lithium embedded, is easy to cause the destruction of electrode structure With unstable SEI film, finally make the capacity rapid decay of battery, the serious silicon based anode material that limits is in lithium ion battery In application.In recent years, the cyclical stability of silicon is mainly improved by the nanosizing of silicon and silicon based composite material, but prepared Journey is complicated, low output, it is difficult to realize commercialization large-scale production.
It is one of the best approach for improving silicon volume expansion problem that designing, which has the Si-C composite material of multi-stage buffering structure,. Document Controlled synthesis of yolk-mesoporous shell Si@SiO2 nanohybrid designed For high performance Li ion battery. RSC Adv., 2014,4 (40): in 20814-20820, Sun Deng the Si-C composite material for utilizing template to prepare a kind of yolk eggshell structure that double carbon-coatings coat, inside and outside double-layer carbon shell is utilized And the cavity building multi-stage buffering structure between silicon particle and carbon-coating alleviates the volume expansion of silicon.Patent 201710232281.7 In obtained a kind of silicon-carbon cathode material of nucleocapsid clad structure, before this using dopamine be carbon source, carbon is obtained by template Silicon particle is coated, secondary cladding then is carried out to obtained carbon coating silicon particle with graphene again and roasts to obtain final shell packet Cover the silicon-carbon cathode material of structure.The Si-C composite material of current multi-stage buffering structure need mostly using such as template it The more complicated preparation method of class, cost are high, it is difficult to meet the needs of commercial Li-ion battery application.
Summary of the invention
The purpose of the present invention is to provide a kind of preparation method of multi-stage buffering structure Si-C composite material and by the party Si-C composite material made from method and application, method of the invention is easy to operate, cost is lower, resulting Si-C composite material tool There is higher chemical property.
To achieve the goals above, one aspect of the present invention provides a kind of multi-stage buffering structure Si-C composite material, the silicon Carbon composite includes by it include wherein nanosizing porous silicon as first order buffer structure, pitch-coating layer is as second Grade buffer structure, skeleton structure constructed by crystalline flake graphite is as third level buffer structure.Wherein pitch-coating layer is divided into body again Phase clad and table phase clad.It is calculated on the basis of the total weight of the negative electrode material, wherein silicone content is 10%-30%, Carbon content is 70%-90%.
Second aspect of the present invention provides a kind of preparation method of Si-C composite material, this method comprises:
(1) diatomite and metal magnesium powder ball milling mixing is uniform, high temperature reduction reaction is carried out under the protection of inert gas.
(2) reduzate obtained by step (1) is first subjected to pickling, being then washed to pH is 6 to 8, centrifuge separation, and vacuum is dry It is dry to obtain porous silicon.
(3) porous silicon obtained by step (2) is carried out that nanosizing processing is sanded, be then centrifuged, vacuum drying obtains Nano-structure porous silicon.
(4) by nano-structure porous silicon obtained by step (3), crystalline flake graphite and pitch wet ball grinding at high speed are mixed Uniform slurry.
(5) by step (4) resulting slurry, after spray-dried machine is granulated, by the silicon carbon material of preparation in inertia gas It is roasted under atmosphere, obtains multi-stage buffering structure silicon-carbon cathode material.
The mass ratio of wherein nano-structure porous silicon, crystalline flake graphite and pitch is 1:2-10:0.5-3, maturing temperature 600- 1200 °C。
Second aspect of the present invention provides Si-C composite material prepared by the above method.
Third aspect present invention provides the cathode including above-mentioned Si-C composite material.
Fourth aspect present invention provides the lithium ion battery including above-mentioned cathode.
The method have the advantages that:
(1) it is raw material using diatomite, porous silicon is obtained by magnesiothermic reduction, most obtains nanoporous through crumbling method is sanded afterwards Silicon realizes the conversion of the energy and material from cheap ore raw materials to high added value.
(2) silicon-carbon cathode material is synthesized by spray granulation, method is simple, it is only necessary to pass through uniformly mixed slurry As soon as crossing step mist projection granulating, multi-stage buffering structure Si-C composite material can be obtained after roasting.
(3) graphite can improve silicon particle as support frame in the multi-stage buffering structure Si-C composite material prepared by Dispersion effect and electric conductivity；Pitch is closely combined silicon particle with graphite, and and graphite as binder and cladding carbon-coating Conductive network is collectively formed, while asphalt carbonization is formed by agraphitic carbon can also improve the interface performance of silicon and electrolyte.
(4) traditional cladded type silicon-carbon cathode material is compared, nanosizing is porous in multi-stage buffering structure Si-C composite material Silicon is as first order buffer structure, and pitch-coating layer as second level buffer structure, make by skeleton structure constructed by crystalline flake graphite For third level buffer structure, multi-stage buffering structure can preferably alleviate the volume expansion of silicon.
Detailed description of the invention
The X-ray diffractogram of porous silicon in Fig. 1 embodiment 1
The X-ray diffractogram of Si/C-1 in Fig. 2 embodiment 1
The scanning electron microscope (SEM) photograph of Si/C-1 in Fig. 3 embodiment 1
The scanning electron microscope (SEM) photograph of partial enlargement for Fig. 3 of Si/C-1 in Fig. 4 embodiment 1
The projection electron microscope of Si/C-1 in Fig. 5 embodiment 1
The projection electron microscope of partial enlargement for Fig. 5 of Si/C-1 in Fig. 6 embodiment 1
The high-resolution of Si/C-1 projects electron microscope in Fig. 7 embodiment 1
Specific embodiment
The endpoint of disclosed range and any value are not limited to the accurate range or value herein, these ranges or Value should be understood as comprising the value close to these ranges or value.For numberical range, between the endpoint value of each range, respectively It can be combined with each other between the endpoint value of a range and individual point value, and individually between point value and obtain one or more New numberical range, these numberical ranges should be considered as specific open herein.
One aspect of the present invention provides a kind of multi-stage buffering structure Si-C composite material, and the Si-C composite material includes nanometer The porous silicon of change is as first order buffer structure, and pitch-coating layer is as second level buffer structure, bone constructed by crystalline flake graphite Frame structure is as third level buffer structure.
According to the present invention, in the Si-C composite material of the invention, the first order buffer structure is by the more of nanosizing What hole silicon was constituted, the porous silicon of nanosizing is exactly size in nanoscale rank, has the simple substance silicon particle of porous structure, preferentially , the partial size of the porous silica particle of the nanosizing is 80-150 nm.The second level buffer structure is by shape after asphalt carbonization At agraphitic carbon constitute, wherein agraphitic carbon includes inside Si-C composite material body phase and surface coating layer, preferential The thickness of surface agraphitic carbon clad is in 10-20 nm.The support frame that the third level buffer structure is made of crystalline flake graphite It constitutes.The size of crystalline flake graphite is 1-10 μm, and the support frame size of the crystalline flake graphite composition is at 5-23 μm.
In the present invention, the nanosizing porous silicon is supported on crystalline flake graphite, and silicon particle and crystalline flake graphite it Between, crystalline flake graphite between each other by formed after asphalt carbonization it is unformed coated, crystalline flake graphite composition support frame in stone It combines closely between ink and graphite and non-fully, it will be appreciated that form three-dimensional network by the agraphitic carbon that the asphalt carbonization is formed Shape structure.
Preferably, in the Si-C composite material, the above-mentioned multi-buffer knot formed by porous nano silicon-graphite-pitch The partial size of structure Si-C composite material is about 5-23 μm.
In accordance with the present invention it is preferred that the content of element silicon is 10-30 weight %, carbon in the Si-C composite material Content be 70-90 weight %.
Second aspect of the present invention provides a kind of preparation method of multi-stage buffering structure Si-C composite material, this method packet It includes: in accordance with the present invention it is preferred that, in the Si-C composite material, the content of element silicon is 10-30 weight %, the content of carbon For 70-90 weight %.
Second aspect of the present invention provides a kind of preparation method of multi-stage buffering structure Si-C composite material, this method packet It includes:
(1) diatomite and metal magnesium powder ball milling mixing is uniform, high temperature reduction reaction is carried out under the protection of inert gas.
(2) reduzate obtained by step (1) is first subjected to pickling, being then washed to pH is 6 to 8, centrifuge separation, and vacuum is dry It is dry to obtain porous silicon.
(3) porous silicon obtained by step (2) is carried out that nanosizing processing is sanded, be then centrifuged, vacuum drying obtains Nano-structure porous silicon.
(4) by nano-structure porous silicon obtained by step (3), crystalline flake graphite and pitch wet ball grinding at high speed are mixed Uniform slurry.
(5) by step (4) resulting slurry, after spray-dried machine is granulated, by the silicon carbon material of preparation in inertia gas It is roasted under atmosphere, obtains multi-stage buffering structure silicon-carbon cathode material.
The mass ratio of wherein nano-structure porous silicon, crystalline flake graphite and pitch is 1:2-10:0.5-3, maturing temperature 600- 1200 °C。
According to the present invention, in step (1) by the element silicon in diatomite by with magnesium metal occur magnesium thermit so that silicon substrate Originally it is completely converted into elemental silicon, and magnesium then exists with magnesia, it is also possible to it there remains the elemental magnesium that part is not reacted completely.Step (2) elemental magnesium that magnesia and remainder do not react completely, which is removed, using pickling in obtains the elemental silicon of porous structure.Step Suddenly carrying out nanosizing processing to porous silicon using sand mill in (3) reduces its size to 80-150 nm.Nanometer is more in step (4) Hole silicon, crystalline flake graphite and pitch wet ball grinding at high speed, obtains uniformly mixed slurry.It utilizes in step (5) and makes by spraying Grain technology obtains nano-structure porous silicon-graphite-pitch precursor, obtains multi-stage buffering structure silicon-carbon cathode material by high-temperature roasting Material.
Wherein, in step (1), in order to enable the silicon in silicon-containing material can fully be converted into elemental silicon, it is preferable that silicon The molar ratio of diatomaceous earth and magnesium powder is 1:0.8-1.2, preferably 1:0.85-1.The magnesium thermit is preferably so that in step (1), institute It states in the product of magnesium thermit, element silicon exists in the form of elemental silicon, and magnesium elements are in the form of magnesia, optional magnesium metal In the presence of.It is highly preferred that forming the product of the magnesium thermit by elemental silicon, magnesia and optional magnesium metal.
Wherein, the granularity of the silicon-containing material can change in a wider range, it is preferable that the granularity of the silicon-containing material It is 1-50 μm, is preferably 1-30 μm, more preferably 1-20 μm.
According to the present invention, the magnesium metal provides preferably in the form of magnesium powder, and especially granularity is 1-100 μm of magnesium powder.
According to the present invention, in order to enable silicon-containing material more can adequately be contacted with magnesium metal, magnesium thermit is being carried out Before, first silicon-containing material and magnesium metal can be mixed, such as by way of ground and mixed, then be sent again hot to magnesium is carried out Reaction.The temperature of the magnesium thermit is 650-750 DEG C, preferably 650-700 DEG C.Preferably, the time of the magnesium thermit For 1-10 h, preferably 2-8 h.Wherein, the magnesium thermit can in any reactor that can be realized above-mentioned condition into Row, such as silicon-containing material and magnesium metal can be first sealed in reactor, then reactor is placed in tube furnace and is added Heat.
Wherein, the inert atmosphere is one of following: nitrogen, argon gas.
According to the present invention, step (2) acid cleaning process is successively to use hydrochloric acid, sulfuric acid, one of hydrofluoric acid or several Kind carries out pickling, and pickling processes remove magnesia, the unreacted diatomite of magnesium metal and part, obtain the silicon of porous structure Grain.Such as the acid solution that the pickling uses is hydrochloric acid, concentration is preferably 1-5 mol/L.
According to the present invention, the dosage of the acid solution can change in a wider range, it is preferable that the institute relative to 1 g The product of calcination process is stated, the dosage of the acid solution is 50-100 mL.
According to the present invention, the porous silicon that sanded treatment process described in step (3) can make magnesium thermit obtain is in ruler It is further reduced on very little, becomes the porous silicon of nanosizing.Wherein sand mill revolving speed is 1800-2400 r/min, is preferably 2000-2300 r/min, the sand milling time be 0.1 h-3 h, be preferably 0.5 h-2 h, in sand milling solvent for use be water, ethyl alcohol, One of acetone or several mixing.
According to the present invention, wet ball grinding purpose described in step (4) is to mix nano-structure porous silicon, crystalline flake graphite, pitch Facilitate the operation of subsequent step at uniform slurry.Wherein the revolving speed of ball mill is 300-1000 r/min, preferably 400- 800r/min；Solvent used in wet ball grinding is water, ethyl alcohol, one of acetone or several mixing.Nano-structure porous silicon, scale The mass ratio of graphite and pitch is 1:2-10:0.5-3, is preferably 1:2-8:0.5-2.
According to the present invention, step (5) mist projection granulating process is both by the dry process of liquid slurry and by nanoporous The process of silicon, crystalline flake graphite, pitch three's mixture pelleting spheroidization.
Second aspect of the present invention provides Si-C composite material prepared by the above method.
As described above, method of the invention can easy to operate, cost chemical property is made lower, environmentally protectively High, particularly high cycle performance Si-C composite material, the Si-C composite material are as described above.Wherein, carbon-coating master It to be agraphitic carbon.
Third aspect present invention provides the cathode including above-mentioned Si-C composite material.
According to the present invention, above-mentioned Si-C composite material is distributed mainly in the negative electrode material layer of cathode as negative electrode active material Material.
Wherein, the cathode mainly includes negative current collector and the negative electrode material layer that is formed thereon.
The negative electrode material layer usually contains negative electrode active material, conductive agent and binder, wherein the negative electrode material is this The above-mentioned Si-C composite material of invention, and conductive agent and binder all use in negative electrode material layer using this field is conventional Conductive agent and binder, for example, the conductive agent can be one of acetylene black, electrically conductive graphite, conductive black etc. or more Kind.The binder for example can be with one of PVDF, carboxymethyl cellulose, sodium carboxymethylcellulose, butadiene-styrene rubber etc. or more Kind.Wherein, the weight ratio of negative electrode active material, conductive agent and binder is preferably 70:5-15:15-25.
Wherein, negative current collector can be for example copper foil, copper mesh etc..
Fourth aspect present invention provides the lithium ion battery including above-mentioned cathode.
According to the present invention, the lithium ion battery can be the construction of the lithium ion battery of this field routine, as long as including Above-mentioned cathode, there is no any restrictions for the other component of the lithium ion battery by the present invention.
The present invention will be described in detail by way of examples below.
Embodiment 1
The present embodiment is for illustrating multi-stage buffering structure Si-C composite material and preparation method thereof of the invention.
(1) 10g diatomite (its partial size is 1-20 μm, the same below) and 8.5 g magnesium powders (granularity is 1-100 μm) are carried out Ball milling mixing, ratio of grinding media to material 1:10, protection gas are argon gas.Uniformly mixed powder is put into closed reactor, is sealed and placed in In the tube furnace of argon gas full of purity 99.9%, heated up with the rate of 5 DEG C/min from room temperature to 675 DEG C and keep 4 h with Carry out magnesium thermit；
(2) product after opening tube furnace magnesium thermit is in (the production of the calcination process relative to 1g of 1mol/L dilute hydrochloric acid Object, the dosage of dilute hydrochloric acid are progress soaking and washing in 100mL)；It then washes and using supercentrifuge in 3900 rmp/min Revolving speed under be centrifuged 3 minutes, remove supernatant and wash centrifugation, so circulation three times to supernatant pH value be 7, then use second Alcohol is centrifuged after washed once, and the sample being collected into is placed 70 DEG C of dry 12h in a vacuum drying oven, obtains porous silicon particle.
(3) the porous silicon particle of 5 g appeal gained is dispersed in the ethanol solution of 150 mL and is placed in sand mill, sand mill 2200 rmp/min of revolving speed, is sanded 1.5 h of time, and product is centrifuged 5 under the revolving speed of 8000 rmp/min using supercentrifuge Minute, supernatant is removed, the sample being collected into is placed into 70 DEG C of dry 12h in a vacuum drying oven, obtains nano-structure porous silicon Grain.
(4) nano-structure porous silicon by 2 g appeal preparation is added in 100 mL deionized waters, is stirred using magnetic stirrer, 500 rmp/min of revolving speed, mixing time are 0.5 h, then add 6 g graphite and 2 g asphalt powders, 800 rmp/min of revolving speed, 2 h of mixing time.The sample that stirring finishes is transferred in 300 mL stainless steel jar mills, planetary ball mill ball milling, ball are used Material mass ratio is 10:1, and revolving speed is 600 rmp/min, and Ball-milling Time is 8 h, and the slurry that ball milling is obtained is placed in 250 mL beakers In, it is granulated using spray dryer, air inlet temperature is 160 °C, and air outlet temperature is 90 °C.By obtained material 1000 Under °C, 2h is roasted in argon atmosphere, heating rate is 5 °C/min.Multi-stage buffering structure silicon-carbon cathode material Si/C-1 is obtained, The content of element silicon is 23 weight %.
XRD qualification result: carrying out X-ray diffraction to magnesium thermit, acid treated product, as a result as shown in Figure 1, can be with Find out, magnesium thermit, acid treated product 2 θ of XRD spectrum have high-visible diffraction maximum within the scope of 10-80 °, own The Si (JPCDS 77-2111) that diffraction maximum can refer to be designated as cube.X-ray is carried out to the Si/C-1 after mist projection granulating, roasting to spread out Penetrate, as a result as shown in fig. 2, it can be seen that 2 θ of XRD spectrum of Si/C-1 composite material have within the scope of 10-80 ° it is high-visible Diffraction maximum, diffraction maximum are respectively the characteristic peak of graphite and silicon.
SEM electron microscope: its SEM of Si/C-1(is schemed as shown in figure 3 and figure 4 using scanning electron microscope) it analyzes； Wherein, Si/C-1 composite material is the more uniform spheric granules (Fig. 3) of partial size, and particle surface is relatively smooth smooth, and partial size is about For 20 μm (Fig. 4).
TEM electron microscope: using scanning electron microscope to Si/C-1 composite material (its TEM figure is as shown in Fig. 5 and Fig. 6) into Row analysis；Wherein, Si/C-1 composite material is fine and close full particle (Fig. 5), evenly dispersed nanometer inside Si/C-1 particle Porous silicon particle (Fig. 6).
HRTEM electron microscope: analyzed Si/C-1 composite material that (its HRTEM figure is shown in figure using high-resolution-ration transmission electric-lens 7), Si/C-1 composite material surface has the agraphitic carbon clad of one layer of 12 nm, this for table asphalt phase be carbonized to be formed it is unformed Carbon coating layer (Fig. 7).
Embodiment 2
The present embodiment is for illustrating Si-C composite material and preparation method thereof of the invention.
According to method described in embodiment 1, the difference is that, the additional amount of step (4) crystalline flake graphite is 7 g, and pitch adds Entering amount is 1 g；The content of the Si-C composite material Si/C-2 element silicon finally obtained is 21 weight %.
Embodiment 3
The present embodiment is for illustrating Si-C composite material and preparation method thereof of the invention.
According to method described in embodiment 1, the difference is that, the additional amount of step (4) crystalline flake graphite is 6.5 g, pitch Additional amount is 1.5 g；The content of the Si-C composite material Si/C-3 element silicon finally obtained is 20 weight %.
Embodiment 4
The present embodiment is for illustrating Si-C composite material and preparation method thereof of the invention.
According to method described in embodiment 1, the difference is that, the additional amount of step (4) crystalline flake graphite is 5.5 g, pitch Additional amount is 2.5 g；The content of the Si-C composite material Si/C-4 element silicon finally obtained is 23 weight %.
Comparative example 1
According to method described in embodiment 1, the difference is that, the additional amount of step (4) crystalline flake graphite is 8 g, is added without pitch；Most The content of the Si-C composite material D1 element silicon obtained eventually is 69 weight %.
Comparative example 2
According to method described in embodiment 1, unlike, the additional amount of step (4) crystalline flake graphite is 6 g, be added without pitch and 2 g of glucose is added；The content of the Si-C composite material D2 element silicon finally obtained is 24 weight %.
Test case
The preparation of battery:
(1) cathode is prepared: respectively using the resulting Si-C composite material of above-mentioned example as negative electrode active material and acetylene black (purchased from Sichuan open source Hui Neng new material Science and Technology Ltd.), carboxymethyl cellulose are (purchased from the intelligent energy new material science and technology of Sichuan open source Co., Ltd) and butadiene-styrene rubber (purchased from Sichuan increase income Hui Neng new material Science and Technology Ltd.) according to weight ratio 70:10:10:10 Yu Shuizhong is uniformly hybridly prepared into negative electrode material slurry, then it is coated in copper foil current collector, in 80 DEG C of vacuum drying oven Middle dry 10h back roller is pressed into cathode pole piece.
It (2) is to electrode with metal lithium sheet, diaphragm uses 2400 diaphragm of Celgard using cathode pole piece as working electrode (U.S.), electrolyte are the LiPF for being added to 10 weight % fluorinated ethylene carbonates (FEC)6Mixed solution (the solvent of (1mol/L) For the EC(ethylene carbonate of volume ratio 1:1:1), DMC(dimethyl carbonate) and DEC(diethyl carbonate) mixed solvent). In UN-Lab type glove box (O2< 1 ppm, H21 ppm of O <) in be assembled into button cell.Silicon-carbon composite wood is respectively adopted as a result, Expect Si/C-1 to Si-C composite material Si/C-4 as negative electrode active material by obtained button cell C1-C4, it is compound using silicon-carbon Material D1 and simple substance silicon materials D2 is as negative electrode active material by obtained button cell DC1 and DC2.
Charging and discharging capacity test: land battery test system is used, with the current density of 0.2 A/g, respectively to above-mentioned The initial charge specific capacity of button cell, coulombic efficiency measures for the first time, the charge specific capacity and corresponding after 100 circulations Coulombic efficiency measures, and calculates capacity retention ratio of the circulation after 100 weeks；The results are shown in Table 1.
Table 1
It can be seen that Si-C composite material of the invention with excellent chemical property by the result of table 1, can be used as negative Pole active material uses.
The preferred embodiment of the present invention has been described above in detail, and still, the present invention is not limited thereto.In technology structure of the invention Think in range, it can be with various simple variants of the technical solution of the present invention are made, including each technical characteristic with any other Suitable method is combined, and it should also be regarded as the disclosure of the present invention for these simple variants and combination, belongs to this hair Bright protection scope.

Claims (7)

1. a kind of multi-stage buffering structure silicon-carbon cathode material comprising wherein the porous silicon of nanosizing is buffered as the first order and tied Structure, pitch-coating layer as second level buffer structure, skeleton structure constructed by crystalline flake graphite as third level buffer structure, Middle pitch-coating layer is divided into body phase clad and table phase clad again, is calculated on the basis of the total weight of the negative electrode material, Middle silicone content is 10%-30%, carbon content 70%-90%.
2. according to claim 1, silicon-carbon cathode material is prepared using nanoporous silicon powder, graphite, pitch as raw material, Wherein the average grain diameter of nanoporous silicon powder is 10 nm-500 nm, preferably 40 nm-300 nm；Graphite be crystalline flake graphite and Spherical graphite, preferably average grain diameter are in 500 crystalline flake graphite between nm-30 μm, and more preferably average grain diameter is at 1 μm -10 Crystalline flake graphite between μm.
3. according to claim 1 to the preparation method of 2 described in any item multi-stage buffering structure silicon-carbon cathode materials, including preparation The step of nano-structure porous silicon, the step of preparing silicon-carbon cathode presoma, and the step of calcining silicon-carbon cathode presoma.
4. the preparation method of multi-stage buffering structure silicon-carbon cathode material according to any one of claims 1 to 3, specific steps It is as follows: (1) it is diatomite and metal magnesium powder ball milling mixing is uniform, high temperature reduction reaction, (2) are carried out under the protection of inert gas Reduzate obtained by step (1) is first subjected to pickling, being then washed to pH is 6 to 8, and centrifuge separation, vacuum drying obtains porous Porous silicon obtained by step (2) is carried out that nanosizing processing is sanded, is then centrifuged, it is more that vacuum drying obtains nanometer by silicon, (3) Hole silicon, (4) by nano-structure porous silicon obtained by step (3), crystalline flake graphite and pitch wet ball grinding at high speed are uniformly mixed Slurry, (5) by step (4) resulting slurry, after spray-dried machine is granulated, by the silicon carbon material of preparation in inertia atmosphere Under roasted, obtain multi-stage buffering structure silicon-carbon cathode material.
5. the preparation method according to claim 4, it is characterised in that: the molar ratio of diatomite and magnesium powder is in step (1) 1:0.8-1.2 preferably 1:0.85-1；The revolving speed of ball mill is 100-400 r/min, preferably 200-300 r/min；Ball milling Process and high temperature reduction process all carry out under an inert atmosphere, and the inert atmosphere is one of following: nitrogen, argon gas； High temperature reduction temperature is 650 °C -750 °C, is preferably 650 °C -700 °C, and step (2) acid cleaning process is successively to use Hydrochloric acid, sulfuric acid, one or more of hydrofluoric acid carry out pickling, and the revolving speed of the centrifuge separation is 3000-4000 r/min, institute Stating vacuum drying temperature is 80 °C -100 °C, and the time is 2 h-5 h, and step (3) the sand mill revolving speed is 1800-2400 R/min is preferably 2000-2300 r/min, and it is preferably 0.5 h-2 h that the sand milling time, which is 0.1 h-3 h, used molten in sand milling Agent is water, ethyl alcohol, one of acetone or several mixing, and the revolving speed of the centrifuge separation is 8000-10000 r/min, institute Stating vacuum drying temperature is 80 °C -100 °C, and the time is 2 h-5 h, and the revolving speed of step (4) ball mill is 300-1000 r/ Min, preferably 400-800r/min；Solvent used in wet ball grinding be water, ethyl alcohol, one of acetone or several mixing, The mass ratio of nano-structure porous silicon, crystalline flake graphite and pitch is 1:2-10:0.5-3, is preferably 1:2-8:0.5-2, spray in step (5) Mist drying machine air inlet temperature is 120-200 DEG C, and outlet temperature is 50 DEG C -130 DEG C；Atomizer is two fluid-type atomizers, into Gas velocity degree is 1-10 L/min, and gas needed for spray dryer is following middle one kind: air, nitrogen, argon gas；Charging rate is 10-50 r/min, the maturing temperature be 600-1200 DEG C, heating rate be 1-10 DEG C/min, preferably 2-8 DEG C/min；It burns The knot time is 1-10h, and preferably 1-8h, the inert atmosphere is one of following: nitrogen, argon gas.
6. the multi-stage buffering structure silicon-carbon cathode material that any preparation method of claim 3-5 is prepared.
7. application of the multi-stage buffering structure silicon-carbon cathode material as lithium ion battery negative material described in claim 6.
CN201810447992.0A 2018-05-11 2018-05-11 A kind of multi-stage buffering structure silicon-carbon cathode material and its preparation method and application Pending CN110474025A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110931756A (en) * 2019-12-13 2020-03-27 成都爱敏特新能源技术有限公司 High-performance silicon-carbon composite negative electrode material with adjustable particle size and preparation method thereof
KR102300157B1 (en) * 2020-03-31 2021-09-08 재단법인 한국탄소산업진흥원 MANUFACTURING METHOD OF CNT-SiOx COMPOSITES FOR LITHUM ION BATTERY AND CATHODE MATERIAL USING THE SAME
CN114914408A (en) * 2021-02-10 2022-08-16 中国石油化工股份有限公司 Silicon-carbon composite material and preparation method and application thereof

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110931756A (en) * 2019-12-13 2020-03-27 成都爱敏特新能源技术有限公司 High-performance silicon-carbon composite negative electrode material with adjustable particle size and preparation method thereof
KR102300157B1 (en) * 2020-03-31 2021-09-08 재단법인 한국탄소산업진흥원 MANUFACTURING METHOD OF CNT-SiOx COMPOSITES FOR LITHUM ION BATTERY AND CATHODE MATERIAL USING THE SAME
CN114914408A (en) * 2021-02-10 2022-08-16 中国石油化工股份有限公司 Silicon-carbon composite material and preparation method and application thereof

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