CN105762360B - Graphene coated silicon composite cathode material and its preparation method and application - Google Patents
Graphene coated silicon composite cathode material and its preparation method and application Download PDFInfo
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- CN105762360B CN105762360B CN201610205702.2A CN201610205702A CN105762360B CN 105762360 B CN105762360 B CN 105762360B CN 201610205702 A CN201610205702 A CN 201610205702A CN 105762360 B CN105762360 B CN 105762360B
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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
- H01M4/58—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
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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
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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
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- H—ELECTRICITY
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- 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
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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
- H01M4/624—Electric conductive fillers
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- 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 graphene coated silicon composite cathode materials and its preparation method and application, it includes the cavity structure being made of graphene and the silicon nanoparticle that is coated in the cavity structure, the partial size of the silicon nanoparticle is 1~100nm, and weight percent shared by silicon nanoparticle is 5~95%.It should be freeze-dried after being mixed under ultrasound condition the preparation method comprises the following steps: disperse graphene oxide and silicon powder in deionized water；Product after the freeze-drying is post-processed, graphene coated silicon composite cathode material is obtained.The negative electrode material can be applied in lithium ion battery.The present invention has the advantages that a kind of synthesized pea shape graphene coated silicon composite cathode material is used in lithium ion battery, discharge capacity is up to 3215mAh/g for the first time, and coulombic efficiency is 74% for the first time, and shows excellent circulation and high rate performance.
Description
Technical field
The present invention relates to a kind of graphene coated silicon composite cathode materials and its preparation method and application, belong to new energy material
Material and its preparation field.
Background technique
Theoretical lithium storage content (4140mAh/g) and abundant resource of the silicon materials because of its superelevation, it is considered to be most have latent
Power replaces graphite to become lithium ion battery negative material of new generation, with meet increasingly developed portable electronic, electric vehicle with
And urgent need of the renewable energy storage to higher energy density and higher power density.
However silicon particle (forms Li in lithiumationxSi) and during de- lithium (becoming simple substance Si again) can occur serious
Powder phenomenon-tion forms molecule.In addition the electric conductivity of silicon particle is relatively poor, and more discontinuous little particles are formed after dusting
Electric conductivity is caused further to weaken.These phenomenons eventually result in the capacity and cycle life all sharp-decays of battery.Volume is swollen
Swollen effect and poor electric conductivity become the main bottleneck for hindering silicium cathode Materials.
In order to overcome this phenomenon, to improve the utilization rate of silicon materials, scientists have done a large amount of research.Many is started
Property work show the silicon materials by regulation synthesis special appearance, or can have in silicon face coated with conductive buffer layer
Effect improves the battery performance of silicium cathode material.If Xiaolin Li is in Nat.Commun.2014,5, the 4105 mesoporous silicon seas delivered
Silk floss can effectively buffer the volume expansion of silicon, which can discharge the capacity of 750mAh/g, pass through under the current density of 1A/g
After crossing 1,000 circulations, capacity retention ratio is up to 80%.And Chaofeng Zhang etc. is in Carbon, 2014,72,169-
The fibrous silicon-carbon composite material of core-shell structure reported on 175 still has 860mAh/g after recycling 200 times under the multiplying power of 0.3C
Capacity.For another example the structure that Zailei Zhang etc. is reported on Angew.Chem.Int.Ed.2014,53,5165-5169 connects
Continuous porous carbon-silicon composite material, capacity are up to 1500mAh/g.
Compared to other carbonaceous materials, graphene makes it show more excellent electricity due to its unique atomic layer structure
The performances such as, calorifics and mechanics.Itself has the double theoretical capacity (744mAh/g) in graphite again.Result of study shows to lead to
Certain way is crossed by graphene and the compound available more excellent electrode material of performance of silicon.And this also becomes current research
One of heat subject.Silicon/graphene composite material preparation method mainly has spray drying process, CVD method, and hydro-thermal method filters
Method etc..Jingbo Chang etc. has obtained Si/ graphene using the method for replacing dip coated Si and graphene on nickel screen and has answered
Condensation material still has the capacity of 700mAh/g when multiplying power is up to 10C.In addition to this, there are also the available performance of CVD method is excellent
Different composite material.But these methods operate more complicated, and cost is relatively high, although obtained composite material property
Can be excellent, but there are also bigger gaps for the theoretical capacity apart from silicon.
Summary of the invention
For the defects in the prior art, it is an object of the invention to overcome above-mentioned the shortcomings of the prior art, provides
A kind of pea shape graphene coated silicon composite cathode material and preparation method thereof.Pea shape graphene coated silicon provided by the invention
Composite material has the characteristics that capacity height and good cycling stability；Preparation method is simple and easy to do, and yield is high, is suitble to extensive work
Industry metaplasia produces.
The present invention is achieved by the following technical solutions:
In a first aspect, the present invention provides a kind of graphene coated silicon composite cathode materials comprising be made of graphene
Cavity structure and the silicon nanoparticle that is coated in the cavity structure, the partial size of the silicon nanoparticle be 1~100nm,
And weight percent shared by silicon nanoparticle is 5~95%.The cavity structure that the graphene is constituted is similar to pea pods, by institute
Silicon particle is stated tightly to coat wherein.
Second aspect, the present invention provides a kind of preparation method of graphene coated silicon composite cathode material as the aforementioned,
It includes the following steps:
It disperses graphite oxide powder and silicon powder in deionized water, is freeze-dried after being mixed under ultrasound condition, ultrasound
Under the conditions of, it not only can be fully dispersed to silicon powder progress, but also graphite oxide powder can be removed, obtain graphene oxide；
Product after the freeze-drying is post-processed, graphene coated silicon composite cathode material is obtained.
Preferably, the temperature of the freeze-drying is -80~10 DEG C, and pressure is 0~101000Pa.If being higher than this
One range, the requirement to instrument and freeze drying equipment will be very high, so that production cost be greatly improved；If being lower than this model
It encloses, it will be difficult to guarantee refrigerating effect.
Preferably, the mass ratio of the graphite oxide powder and silicon powder is 1:(0.2~5), the graphite oxide powder
Mass ratio with deionized water is 1:(0.2~5).The ratio and graphite oxide powder and deionized water of graphite oxide powder and silicon powder
Ratio graphite oxide powder can be made fully dispersed in deionized water, while keeping silicon powder fully dispersed in graphite oxide.
Preferably, the method for the post-processing is one of following processing:
A, it disperses the product after freeze-drying in solvent, solvent thermal reaction is carried out at 100~240 DEG C, obtains stone
Black alkene coats silicon composite cathode material；The temperature range can make graphene oxide be reduced to graphene, cannot reach lower than 100 DEG C
To reduction effect, the requirement higher than 240 DEG C to pressure vessel can be very high, and production cost is greatly improved.
B, the product after freeze-drying is subjected at 200~1200 DEG C high-temperature calcination, it is compound obtains graphene coated silicon
Negative electrode material.The calcination temperature range can make graphene oxide be reduced to graphene, and reduction effect cannot be reached lower than 200 DEG C
Fruit, requirement higher than 1200 DEG C to calciner can be very high, lead to that increased production cost.
Preferably, the solvent is selected from water, methanol, ethyl alcohol, ethylene glycol, ether, acetone, tetrahydrofuran, benzene, first
One of benzene, dimethylbenzene, N,N-dimethylformamide, N-Methyl pyrrolidone are a variety of.
Preferably, the heating rate of the high-temperature calcination is 0.5~40 DEG C/min.The heating rate can ensure that
Graphene oxide is effectively reduced to graphene, will not generate apparent bulking effect.
Preferably, the temperature of the high-temperature calcination is 700~1000 DEG C.
Preferably, the high-temperature calcination is carried out in any one following atmosphere:
Air, nitrogen, argon gas or hydrogen volume score be 1~20% it is hydrogen-argon-mixed.
The third aspect, the present invention also provides a kind of graphene coated silicon composite cathode material as the aforementioned prepare lithium from
Application in sub- battery.
Compared with prior art, the present invention have it is following the utility model has the advantages that
1, the method that the present invention is creatively combined using freeze-drying with heat treatment, synthetic method is simple and easy, no
It needs to adjust pH value, does not also need any reducing agent or surfactant, do not need using expensive instrument, it is also not cumbersome
Experimental procedure.Used abundant raw material, and cheap and easy to get, product yield high, solvent for use can be also recycled, entire real
Process efficiency height is tested, controllability is strong, and it is low in cost, it is simple and environmentally-friendly, it is suitble to industrialized production；
2, in synthesis process of the invention, first in the uniformly mixed situation of graphite oxide powder and silicon powder dry by freezing
It is dry, silicon powder is fixed in the graphene oxide for shrinking and reuniting, then by being further heat-treated, graphene oxide is reduced
While further shrinkage crimping, silicon powder particle is more closely wrapped up wherein, this allows for material knot prepared by the present invention
Structure is stablized, and pattern is uniform；
3, in the composite material synthesized by the present invention, the graphene for being closely coated on silicon face can greatly improve material
Electric conductivity, and closing or the closed cavity of class that graphene is formed can effectively buffer caused by silicon particle volume expansion
Negative effect, to maintain the stability of material structure；
4, a kind of synthesized pea shape graphene coated silicon composite cathode material is used in lithium ion battery, is put for the first time
Capacitance is up to 3215mAh/g, and coulombic efficiency is 74% for the first time, and shows excellent circulation and high rate performance.
Detailed description of the invention
Upon reading the detailed description of non-limiting embodiments with reference to the following drawings, other feature of the invention,
Objects and advantages will become more apparent upon:
Fig. 1 is the SEM figure of pea shape graphene coated silicon composite cathode material made from the embodiment of the present invention 1；
Fig. 2 be the present invention use embodiment 1 to obtain novel anode material hydroxy chloride cobalt be assembled into lithium ion battery with
The current density of 100mA/g, the charging and discharging curve figure twice before the voltage range of 1.2~0.01V；
Fig. 3 be the present invention use embodiment 7 to obtain novel anode material hydroxy chloride cobalt be assembled into lithium ion battery with
The current density of 100mA/g, the charging and discharging curve figure twice before the voltage range of 1.2~0.01V.
Specific embodiment
The present invention is described in detail combined with specific embodiments below.Following embodiment will be helpful to the technology of this field
Personnel further understand the present invention, but the invention is not limited in any way.It should be pointed out that the ordinary skill of this field
For personnel, without departing from the inventive concept of the premise, various modifications and improvements can be made.These belong to the present invention
Protection scope.
In the present invention graphite oxide the preparation method is as follows:
Under 0~20 DEG C of water-bath, 3~5g graphite powder is added in 100~150mL concentrated sulfuric acid, 10~20g is added with stirring
Potassium permanganate stirs 3~4h, and temperature rises to 30~35 DEG C, and 300~500mL deionized water is added, and stirs 1~3h, is added 15
The hydrogenperoxide steam generator that~25mL mass concentration is 30% stirs 5~20 minutes, by centrifuge separation, with mass concentration 5%
After hydrochloric acid solution, deionized water are washed and dried repeatedly, graphite oxide is obtained.
The assembling of lithium ion battery and test method are as follows:
By the binder of pea shape graphene coated silicon composite cathode material and 20wt.% of the invention, (solid content is
The N- crassitude for the Kynoar that the butadiene-styrene rubber of 2wt.%-sodium carboxymethylcellulose lotion or concentration are 0.02g/mL
Ketone solution) and 20wt.% conductive agent (Super P conductive carbon black) mixing, after mixing evenly be coated in copper foil on, be put into baking oven
In 60~80 DEG C dry.It is washed into pole piece with the formed punch of 12~16mm of diameter again, is put into vacuum drying oven and is done at 60~120 DEG C
It dry 8~12 hours, is then transferred into the glove box full of argon gas.It is to electrode with metal lithium sheet, ENTEK PE perforated membrane is
Diaphragm, the ethylene carbonate and dimethyl carbonate (volume ratio 1:1) mixed solution of 1mol/L lithium hexafluoro phosphate are electrolyte, and
The fluorinated ethylene carbonate that 10% (volume fraction) is added in the electrolyte, is assembled into CR2016 button cell, in LAND battery
Constant current charge-discharge performance test is carried out in test macro (offer of Wuhan Jin Nuo Electronics Co., Ltd.), charge and discharge blanking voltage is opposite
In Li/Li+For 1.2~0.01V.
The electrolyte of lithium ion battery is not limited to the ethylene carbonate of above-mentioned lithium hexafluoro phosphate and mixing for dimethyl carbonate
Solution is closed, can be the electrolyte of lithium salts, solvent and electrolysis additive composition, the lithium salts includes lithium hexafluoro phosphate
(LiPF6), LiBF4 (LiBF4) or lithium perchlorate (LiClO4) etc. inorganics salt and biethyl diacid lithium borate
(LiBOB), the organics salt such as two (trifluoromethane sulfonic acid) imine lithiums (LiTFSI), the solvent include ethylene carbonate (EC),
At least one of propene carbonate (PC), dimethyl carbonate (DMC) and diethyl carbonate (DEC), lithium salt in electrolyte
Less than 2mol/L.The electrolysis additive includes fluorinated ethylene carbonate (FEC), vinylene carbonate (VC) etc..
Embodiment 1
The present embodiment is related to a kind of preparation method of pea shape graphene coated silicon composite cathode material, the method includes
Following steps:
It disperses nano silica fume and 40mg graphite oxide powder that 80mg partial size is 20nm or so in 20ml deionized water, surpasses
After sound dispersion, in -50 DEG C, when pressure is 5Pa after freeze-drying 36 hours, by the sample dispersion after drying in 40ml dehydrated alcohol
In, it is placed in the reaction kettle of inner liner polytetrafluoroethylene and carries out solvent thermal reaction, reaction temperature is 170 DEG C, is reacted 12 hours, reaction
Product afterwards is washed with deionized, and in -50 DEG C, is freeze-dried 24 hours when pressure is 5Pa, obtains pea shape graphene coated
Silicon composite cathode material.In the composite material, mass ratio shared by nano silicon particles is about 83%.
The SEM of pea shape graphene coated silicon composite cathode material made from the present embodiment schemes as shown in Figure 1, composite material
Pea shape microscopic appearance is presented, be wrapped in outer layer is graphene, and silicon particle is wrapped by wherein.
Pea shape graphene coated silicon composite cathode material made from the present embodiment is assembled into battery and carries out charge and discharge electrical measurement
Examination, as shown in Fig. 2, battery is under the current density of 100mA/g, in the voltage range of 1.2~0.01V when charge and discharge, for the first time
Embedding lithium capacity is 3215mAh/g, and reversible capacity is 2379mAh/g for the first time, and first circle coulombic efficiency is 74%.What is recycled for the second time can
Inverse capacity is 2374mAh/g, and almost without loss compared with for the first time, it is 95% that coulombic efficiency, which also increases rapidly,.
Comparative example 1
80mg silicon powder (average grain diameter 20nm) and 40mg graphite oxide powder are dispersed in 20ml deionized water, ultrasound
60min makes it be uniformly dispersed, and is then spray-dried, and for inlet temperature at 220 DEG C, outlet temperature removes moisture at 140 DEG C,
Obtain the composite material of graphene oxide and silicon；Then it places it in high temperature furnace, is passed through hydrogen-argon-mixed (hydrogen containing 5v/v%
Gas), 600 DEG C of progress the high temperature anneals are warming up to, 5 hours is kept the temperature, restores graphene oxide, then naturally cool to
Room temperature obtains silicon graphene composite negative pole material, which forms spherical compound of diameter about 400nm
Grain.In above-mentioned preparation process, the graphene oxide of addition restores to the end generates graphene, the proportion of goods damageds 40%.
Silicon graphene composite material obtained is assembled into battery and carries out charge-discharge test, in 100mA/g
Current density under, in the voltage range of 1.2~0.01V when charge and discharge, initial coulomb efficiency 64%, reversible appearance for the first time
Amount is only 1748mAh/g, and the reversible capacity of the 2nd circulation is 1602mAh/g, and decaying is obvious.
Embodiment 2
The present embodiment is related to a kind of preparation method of pea shape graphene coated silicon composite cathode material, the method includes
Following steps:
It disperses nano silica fume and 10mg graphite oxide powder that 80mg partial size is 1nm or so in 50ml deionized water, surpasses
After sound dispersion, in 10 DEG C, when pressure is 101000Pa after freeze-drying 72 hours, by the sample dispersion after drying in 10ml N,
In dinethylformamide, it is placed in the reaction kettle of inner liner polytetrafluoroethylene and carries out solvent thermal reaction, reaction temperature is 240 DEG C,
Reaction 2 hours, the product after reaction is washed with deionized, and in 10 DEG C, is freeze-dried 72 hours, obtains when pressure is 101000Pa
To pea shape graphene coated silicon composite.In the composite material, mass ratio shared by nano silicon particles is about 95%.
Pea shape graphene coated silicon composite cathode material made from the present embodiment is assembled into battery and carries out charge and discharge electrical measurement
Examination is 50mA/g in current density, and voltage range carries out charge-discharge test when being 1.2~0.01V.Embedding lithium capacity is up to for the first time
3810mAh/g, reversible capacity is 2023mAh/g for the first time, and first circle efficiency is 53%.
Embodiment 3
The present embodiment is related to a kind of preparation method of pea shape graphene coated silicon composite, and the method includes as follows
Step:
It disperses nano silica fume and 200mg graphite oxide powder that 5mg partial size is 100nm or so in 40ml deionized water,
After ultrasonic disperse, in -80 DEG C, when pressure is 0Pa after freeze-drying 2 hours, by the sample dispersion after drying in 200ml ethylene glycol
In, it is placed in the reaction kettle of inner liner polytetrafluoroethylene and carries out solvent thermal reaction, reaction temperature is 100 DEG C, is reacted 72 hours, reaction
Product afterwards is washed with deionized, and in -80 DEG C, is freeze-dried 12 hours when pressure is 0Pa, obtains pea shape graphene coated
Silicon composite.In the composite material, mass ratio shared by nano silicon particles is about 5%.
Pea shape graphene coated silicon composite cathode material made from the present embodiment is assembled into battery and carries out charge and discharge electrical measurement
Examination is 50mA/g in current density, and voltage range carries out charge-discharge test when being 1.2~0.01V.Embedding lithium capacity is for the first time
1203mAh/g, reversible capacity is 554mAh/g for the first time, and first circle efficiency is 53%.
Embodiment 4
The present embodiment is related to a kind of preparation method of pea shape graphene coated silicon composite, and the method includes as follows
Step:
It disperses nano silica fume and 40mg graphite oxide powder that 80mg partial size is 40nm or so in 40ml deionized water, surpasses
After sound dispersion, in -80 DEG C, when pressure is 0Pa after freeze-drying 12 hours, the sample after drying is placed in tube furnace, in nitrogen
Under gas shielded, 1000 DEG C are warming up to the speed of 0.5 DEG C/min, is naturally cooling to room temperature after keeping 2h to get pea shape stone is arrived
Black alkene coats silicon composite.In the composite material, mass ratio shared by nano silicon particles is about 90%.
Pea shape graphene coated silicon composite cathode material made from the present embodiment is assembled into battery and carries out charge and discharge electrical measurement
Examination is 50mA/g in current density, and voltage range carries out charge-discharge test when being 1.2~0.01V.Embedding lithium capacity is for the first time
3741mAh/g, reversible capacity is 2821mAh/g for the first time, and first circle efficiency is 75%.Second of reversible capacity is 1957mAh/g, library
Human relations efficiency is 87%.
Embodiment 5
The present embodiment is related to a kind of preparation method of pea shape graphene coated silicon composite, and the method includes as follows
Step:
It disperses nano silica fume and 80mg graphite oxide powder that 80mg partial size is 40nm or so in 80ml deionized water, surpasses
After sound dispersion, in -80 DEG C, it is freeze-dried 12 hours, the sample after drying is placed in tube furnace, in 5v/ when pressure is 0Pa
Under v% hydrogen-argon-mixed atmosphere, 700 DEG C are warming up to the speed of 10 DEG C/min, is naturally cooling to room temperature after keeping 6h to get pea is arrived
Beans shape graphene coated silicon composite.In the composite material, mass ratio shared by nano silicon particles is about 70%.
Pea shape graphene coated silicon composite cathode material made from the present embodiment is assembled into battery and carries out charge and discharge electrical measurement
Examination is 50mA/g in current density, and voltage range carries out charge-discharge test when being 1.2~0.01V.Embedding lithium capacity is for the first time
2905mAh/g, reversible capacity is 2021mAh/g for the first time, and first circle efficiency is 70%.
Embodiment 6
The present embodiment is related to a kind of preparation method of pea shape graphene coated silicon composite, and the method includes as follows
Step:
It disperses nano silica fume and 80mg graphite oxide powder that 80mg partial size is 40nm or so in 80ml deionized water, surpasses
After sound dispersion, in -80 DEG C, when pressure is 0Pa after freeze-drying 12 hours, the sample after drying is placed in tube furnace, in sky
Under gas atmosphere, 100 DEG C are warming up to the speed of 50 DEG C/min, is naturally cooling to room temperature after keeping 72h to get pea shape graphite is arrived
Alkene coats silicon composite.In the composite material, mass ratio shared by nano silicon particles is about 60%.
Pea shape graphene coated silicon composite cathode material made from the present embodiment is assembled into battery and carries out charge and discharge electrical measurement
Examination is 100mA/g in current density, and voltage range carries out charge-discharge test when being 1.2~0.01V.Embedding lithium capacity is for the first time
1815mAh/g, reversible capacity is 1001mAh/g for the first time, and first circle efficiency is 55%.
Embodiment 7
The present embodiment is related to a kind of preparation method of pea shape graphene coated silicon composite cathode material, the method includes
Following steps:
It disperses nano silica fume and 50mg graphite oxide powder that 80mg partial size is 20nm or so in 20ml deionized water, surpasses
After sound dispersion, in -50 DEG C, when pressure is 1Pa after freeze-drying 36 hours, by the sample dispersion after drying in 40ml deionized water
In, it is placed in the reaction kettle of inner liner polytetrafluoroethylene and carries out solvent thermal reaction, reaction temperature is 170 DEG C, is reacted 12 hours, reaction
Product afterwards is washed with deionized, and in -50 DEG C, is freeze-dried 24 hours when pressure is 1Pa, obtains pea shape graphene coated
Silicon composite cathode material.In the composite material, mass ratio shared by nano silicon particles is about 80%.
Pea shape graphene coated silicon composite cathode material made from the present embodiment is assembled into battery and carries out charge and discharge electrical measurement
Examination, as shown in figure 3, battery is under the current density of 100mA/g, in the voltage range of 1.2~0.01V when charge and discharge, for the first time
Embedding lithium capacity is 2756mAh/g, and reversible capacity is 1973mAh/g for the first time, and first circle coulombic efficiency is 71.6%.It recycles for the second time
Reversible capacity is 1972mAh/g, and it is 94% that coulombic efficiency, which also increases rapidly,.
It in summary it can be seen, the method that the present invention is creatively combined using freeze-drying with heat treatment, synthetic method
It is simple and easy, adjustment pH value is not needed, any reducing agent or surfactant are not needed yet, is not needed using expensive instrument,
Also not cumbersome experimental procedure.Used abundant raw material, and cheap and easy to get, product yield high, solvent for use can also be returned
It receives and utilizes, whole experiment process is high-efficient, and controllability is strong, and it is low in cost, it is simple and environmentally-friendly, it is suitble to industrialized production；
In synthesis process of the invention, first in the uniformly mixed situation of graphite oxide powder and silicon powder dry by freezing
It is dry, silicon powder is fixed in the graphene oxide for shrinking and reuniting, then by being further heat-treated, graphene oxide is reduced
While further shrinkage crimping, silicon powder particle is more closely wrapped up wherein, this allows for material knot prepared by the present invention
Structure is stablized, and pattern is uniform；
By inventing in synthesized composite material, the graphene for being closely coated on silicon face can greatly improve material
Electric conductivity, and closing or the closed cavity of class that graphene is formed can effectively buffer caused by silicon particle volume expansion
Negative effect, to maintain the stability of material structure；
It is used in lithium ion battery by a kind of synthesized pea shape graphene coated silicon composite cathode material, puts for the first time
Capacitance is up to 3215mAh/g, and coulombic efficiency is 74% for the first time, and shows excellent circulation and high rate performance.
Specific embodiments of the present invention are described above.It is to be appreciated that the invention is not limited to above-mentioned
Particular implementation, those skilled in the art can make various deformations or amendments within the scope of the claims, this not shadow
Ring substantive content of the invention.
Claims (2)
1. a kind of preparation method of graphene coated silicon composite cathode material, which comprises the steps of:
It disperses nano silica fume and 40mg graphite oxide powder that 80mg partial size is 20nm in 20ml deionized water, ultrasonic disperse
Afterwards, it in -50 DEG C, when pressure is 5Pa after freeze-drying 36 hours, by the sample dispersion after drying in 40ml dehydrated alcohol, sets
Solvent thermal reaction is carried out in the reaction kettle of inner liner polytetrafluoroethylene, reaction temperature is 170 DEG C, is reacted 12 hours, after reaction
Product is washed with deionized, and in -50 DEG C, is freeze-dried 24 hours when pressure is 5Pa, obtains pea shape graphene coated silicon
Composite negative pole material.
2. graphene coated silicon composite cathode material prepared by a kind of preparation method as described in claim 1 prepare lithium from
Application in sub- battery.
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| CN106159227A (en) * | 2016-07-27 | 2016-11-23 | 电子科技大学 | silicon-carbon composite lithium ion battery cathode material and preparation method thereof |
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| CN112018336A (en) * | 2019-05-29 | 2020-12-01 | 新奥科技发展有限公司 | Silicon-carbon composite material, preparation method thereof, positive electrode material and aluminum ion battery |
| CN111048757B (en) * | 2019-12-12 | 2022-06-10 | 中南大学 | B. N-codoped graphene-coated silicon nano anode material and preparation method thereof |
| CN111106338B (en) * | 2019-12-26 | 2021-06-08 | 浙江大学 | Preparation method of silicon/amorphous carbon/graphene lithium ion battery anode material |
| CN114335527B (en) * | 2020-09-29 | 2024-04-09 | 山东海科创新研究院有限公司 | High-performance silicon-carbon composite material, preparation method thereof and lithium ion battery |
| CN112940690B (en) * | 2021-02-05 | 2021-11-02 | 中国科学院苏州纳米技术与纳米仿生研究所南昌研究院 | Phase change energy storage material with pod structure and preparation method and application thereof |
| CN114122372B (en) * | 2021-11-10 | 2024-03-29 | 云南中晟新材料有限责任公司 | Low-expansion silicon-carbon negative electrode material for lithium ion battery and preparation method thereof |
| CN114933299B (en) * | 2022-06-14 | 2023-07-14 | 西安交通大学苏州研究院 | Functionalized modified graphene oxide, preparation method and application |
| CN117276523A (en) * | 2023-06-20 | 2023-12-22 | 湖北斯诺新材料科技有限公司 | Preparation method and application of silicon-carbon composite material |
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