CN109817957A - A kind of preparation method of pitch-coating silicon doping natural flake graphite negative electrode material - Google Patents
A kind of preparation method of pitch-coating silicon doping natural flake graphite negative electrode material Download PDFInfo
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Abstract
The present invention provides a kind of preparation methods of pitch-coating silicon doping natural flake graphite negative electrode material, belong to negative electrode material preparation technical field, comprising the following steps: mix nitric acid solution with natural flake graphite, magnetic agitation reaction is filtered, washed, dry；Nano silica fume is weighed, dissolution is added to absolute ethanol, adds calgon, stirs evenly rear sonic oscillation, adjusts pH value, silane coupling agent is added, magnetic agitation is heated to reflux, and is sufficiently reacted, is then centrifuged for, and is dried, grinding；Will treated natural flake graphite nano silica fume mix with treated, toluene is added in grinding, and nitrogen protection is stirred to react, and filters, washing, drying；NG/Si composite material and pitch toluene solution are mixed, feeding is dried in the shade, then constant temperature drying, is ground, and pyrolysis obtains product.The method of the present invention improves the electrochemistry cycle performance and specific discharge capacity of natural flake graphite.
Description
Technical field
The invention belongs to graphite modified technical fields, and in particular to a kind of pitch-coating silicon doping natural flake graphite cathode
The preparation method of material.
Background technique
Lithium ion battery is the representative of contemporary heavy-duty battery, is a kind of New Green Energy product-derived, be widely used in information,
Telecommunication and power industry.Carbon negative pole material is widely used in commodity lithium ion battery at present.Wherein, graphite negative electrodes material is come with it
Source is extensive, and performance is stablized, and several big advantages such as energy conservation and environmental protection become the main Types of carbon negative pole material.
Graphite material mainly includes natural graphite, artificial graphite and various graphitized carbons (such as graphited coke, graphitization
Carbon fiber, graphitized intermediate-phase carbosphere) three classes.Natural graphite refers to that natural graphite mine passes through mining, flotation, screening and purification
Natural graphite material obtained.The natural graphite in China is broadly divided into amorphous graphite (micro crystal graphite) and crystalline flake graphite two
Kind, micro crystal graphite particle bad mechanical property is easily broken, therefore, it is difficult to carry out shaping spheroidising, therefore practical at present
Natural graphite is mainly crystalline flake graphite.The problem of crystalline flake graphite is primarily present as lithium ion battery negative material has: natural stone
Ink is poor with compatibility of electrolyte, and during first charge-discharge, organic solvent and lithium ion are embedded in restore in graphite flake layer altogether and generate
Gas, and a part of lithium is consumed, cause first charge discharge efficiency low；Graphite spacing is less than the crystal face interlayer of compound L i-GIC between lithium layer
Away from, cause in charge and discharge process, graphite particle repeated expansion and shrinkage, cause graphite linings peel off, dusting, influence circulating battery stablize
Property.It is generally necessary to be modified processing to crystalline flake graphite, specific method includes shaping classification, surface oxidation, cladding, doping etc..
Publication No. provides a kind of inorganic doping/coating modification natural graphite, system for the patent document of CN103972508A
Preparation Method and its application.Preparation method includes the following steps: natural graphite and oxidizing acid, inorganic doping raw material in reaction kettle
Middle carry out hydro-thermal reaction, reaction temperature is between 90 ~ 180 DEG C, the reaction time 0.5 ~ 12 hour, obtains product expanded graphite A；It will
Expanded graphite A is dried in baking oven, obtains dry expanded graphite B；Under protective atmosphere to expanded graphite B 600 ~ 1600 DEG C into
Row high-temperature process, while being passed through itrogenous organic substance and forming one layer of nitrogen clad in expanded graphite B surface, finally obtain modified natural
Graphite.The preparation method simple process of the invention, easily controllable, raw material sources are extensively and cheap, and material is reproducible, and takes into account
The advantages of doping and coating modification, but the specific capacity of gained modified natural graphite is lower.
The patent document of publication number CN105977489A discloses a kind of lithium ion battery modification of microcrystalline graphite cathode material
Preparation method, comprise the following steps that 1) shaping crush: by natural micro crystal graphite be added to agitating ball mill carry out ball milling 1 ~
4h, then filtration drying obtains the graphite composite powder after ball milling；2) it coats: the powdered graphite that step 1) is obtained and catalyst, drip
After blueness mixing, 0.5 ~ 1h of heating stirring at 150 ~ 200 DEG C is vacuumized；Its vacuum degree is 500 ~ 2000Pa, and mixing speed is
2500~3000rpm；3) be graphitized: by after cladding powdered graphite carry out 10 ~ 48h of graphitization processing, carbonization temperature be 2800 ~
3200 degree, obtain modification of microcrystalline graphite cathode material.This method uses graphitization by the purifying of natural micro crystal graphite, being not directed to
Learn the poisonous and harmful reagent in method of purification, environment-friendly and green；Catalyst is added during this method cladding, graphitization can be promoted
Degree, increases substantially its capacity, and coating under vacuum effectively to wrap up surface, promotes tap density and table is compared in reduction
Area, cycle performance are greatly improved.But the specific capacity of negative electrode material obtained by this method is lower.
Summary of the invention
The technical problem to be solved by the present invention is in view of the deficiencies of the prior art, provide a kind of pitch-coating silicon doping
The preparation method of natural flake graphite negative electrode material, to improve the electric specific capacity and cycle performance of natural flake graphite.
In order to solve the above technical problems, the technical scheme adopted by the invention is that:
A kind of preparation method of pitch-coating silicon doping natural flake graphite negative electrode material, comprising the following steps:
S1: nitric acid solution is mixed with natural flake graphite, is reacted 2-4 hours under magnetic agitation, and filtering obtains the first sediment,
First sediment is washed, dry, the natural flake graphite that obtains that treated；
S2: weighing nano silica fume, is added to absolute ethanol dissolution, adds calgon, after mixing evenly sonic oscillation, ice
Second acid for adjusting pH value is subsequently added into silane coupling agent, and magnetic agitation is heated to reflux, and sufficiently reacts, and is then centrifuged for de- ethyl alcohol, dries
It is dry, grinding, the nano silica fume that obtains that treated；
S3: will treated the natural flake graphite with it is described treated that nano silica fume mixes, grind, in gained mixture
Toluene is added, under nitrogen protection, 70-75 DEG C is stirred to react 5-6 hours, and filtering obtains the second sediment, and it is heavy to wash described second
Starch, it is dry, obtain NG/Si composite material；
S4: the NG/Si composite material being added in powder mixer, pitch toluene solution is poured into top spray device, is opened
Top spray device, stirring mix the NG/Si composite material and pitch toluene solution, and feeding is dried in the shade, and then constant temperature drying, grinds
Mill, pyrolysis, obtains product.
Preferably, the concentration of the nitric acid solution is 0.1-0.25mol/l, and the natural flake graphite quality and nitric acid are molten
The ratio of liquid product is 1:(40-50) g/ml.
Preferably, the partial size D of the natural flake graphite90It is 5-15 microns.
Preferably, the temperature of magnetic agitation described in step S1 is 23-28 DEG C, and the temperature of the drying is 80-85 DEG C.
Preferably, the pH value is 6.2-6.5.
Preferably, the mass ratio of the nano silica fume, calgon and silane coupling agent is 100:(2-5): (9-12).
Preferably, the ratio of the pitch toluene solution studies on asphaltene amount and volume of toluene is 0.08-0.12g/ml.
Preferably, the mass ratio of the pitch and natural flake graphite is (7-12): 100.
Preferably, the temperature of constant temperature drying described in step S4 is 60-65 DEG C.
Preferably, the process conditions of the pyrolysis are as follows: in N2Under protection, start to be warming up to the speed of 12-15 DEG C/min
400-450 DEG C, 3-5h is kept the temperature, then be warming up to 800-850 DEG C with the speed of 6-8 DEG C/min, keep the temperature 1-3h, naturally cool to room
Temperature.
Compared with prior art, beneficial effects of the present invention are as follows:
In view of the deficiencies of the prior art, the present invention provides a kind of systems of pitch-coating silicon doping natural flake graphite negative electrode material
Preparation Method so that the electrochemistry cycle performance and specific discharge capacity of natural flake graphite are improved, make natural flake graphite with
Solvent has higher compatibility.
Firstly, the present invention carries out oxidation modification to natural flake graphite using concentrated nitric acid, by surface oxidation treatment, not only
Nanoscale micropore can be increased on the surface of graphite, provide more spaces for the insertion of lithium ion, that improves graphite material can
Inverse capacity；The higher position of graphite surface activity can be eliminated so that graphite surface has relatively uniform reactivity, prevent because
Activity is inhomogenous, and surface curvature is larger, the accumulation of the generations such as point effect, and the higher position of reactivity and electrolyte are sent out
Raw more violent reaction, causes the SEI film thickness generated different；Non-uniform SEI film more holds during charge and discharge
Breakage easily occurs, the chemical property of active material is impacted.It is closed in addition, the control of degree of oxidation has surface oxidation
The influence of keyness.The oxidation of appropriateness is conducive to improve the charge-discharge performance of material；But graphite surface oxidation is excessively violent, just has
A large amount of oxygen-containing group occurs, and surface is irregular also to be greatly improved, so that the irreversible lithium ion during first charge-discharge damages
Consumption increases, and the property of the SEI film resulted in is deteriorated, and solvation lithium ion can enter graphite layers, reduces graphite instead
Chemical property.The present invention combines overall performance by further investigation, using concentrated nitric acid as oxidant, to graphite surface
Uniform alumina is carried out, and when the concentration of nitric acid solution is 0.1-0.25mol/l, natural flake graphite quality and nitric acid solution body
Long-pending ratio be 1:(40-50) g/ml when, oxidation material shows more excellent charge/discharge capacity and cycle performance.
Secondly, the present invention is using element silicon as doped chemical, it is molten in ethyl alcohol using calgon raising nano-silicon first
Dispersibility in liquid is then adjusted to suitable pH, using silane coupling agent, such as: KH550, KH560 carry out surface to nano-silicon
It is modified, improve its compatibility with organic environment by carrying out surface organic coating to nano-silicon, moreover it is possible to effectively prevention particle cluster
It is poly-, improve its dispersibility, to improve the combined efficiency of nano-silicon particle and natural flake graphite, experiment shows doped silicon member
Element can effectively improve the electrochemical properties of graphite, and silicon belongs to storage lithium active material, can form active material with graphite,
The two synergistic effect is played, cycle performance is improved.
Again, the present invention forms one layer of specific surface area in graphite surface after high temperature carbonization in Graphite Coating pitch
On the one hand lesser amorphous carbon avoids solvent and contacts with the direct of graphite, inhibits the insertion due to solvent molecule and cause
Graphite flake layer obscission, expand the range of choice of electrolyte, a large amount of disordered structure of another aspect amorphous carbon layer
In the presence of reducing the barrier effect between the directionality and particle of diffusion, substantially improve the performance of graphite electrode
The present invention is handled by carrying out surface oxidation, element silicon doping and pitch-coating to natural flake graphite, so that naturally
The discharge capacity for the first time of crystalline flake graphite negative electrode material improves 30% or more；Capacity retention ratio is on 76% or so after circulation 50 times；This
Treated that material shows good chemical property for invention.
Specific embodiment
For a better understanding of the present invention, the contents of the present invention, but this hair are further fairly set out below with reference to embodiment
Bright protection content is not limited solely to the following examples.In the following description, give a large amount of concrete details so as to
More thorough understanding of the invention is provided.It will be apparent, however, to one skilled in the art that the present invention can be with
It is carried out without one or more of these details.In other examples, in order to avoid confusion with the present invention, for
Some technical characteristics well known in the art are not described.
Embodiment 1
A kind of preparation method of pitch-coating silicon doping natural flake graphite negative electrode material, comprising the following steps:
S1: nitric acid solution is mixed with natural flake graphite, is reacted 2 hours under magnetic agitation, and filtering obtains the first sediment, washes
The first sediment is washed, dry, the natural flake graphite that obtains that treated；
S2: weighing nano silica fume, is added to absolute ethanol dissolution, adds calgon, after mixing evenly sonic oscillation, ice
Second acid for adjusting pH value is subsequently added into silane coupling agent, and magnetic agitation is heated to reflux, and sufficiently reacts, and is then centrifuged for de- ethyl alcohol, dries
It is dry, grinding, the nano silica fume that obtains that treated；
S3: will treated natural flake graphite nano silica fume mixes with treated, grind, first be added in gained mixture
Benzene, under nitrogen protection, 70 DEG C are stirred to react 6 hours, and filtering obtains the second sediment, wash the second sediment, dry, obtain NG/
Si composite material；
S4: NG/Si composite material being added in powder mixer, pitch toluene solution is poured into top spray device, opens top spray
Device, stirring mix NG/Si composite material and pitch toluene solution, and feeding is dried in the shade, then constant temperature drying, grind, pyrolysis,
Obtain product.
In the present embodiment, the quality of natural flake graphite is 10g, and following embodiments are identical.
The concentration of nitric acid solution is 0.25mol/l, and natural flake graphite quality and the ratio of nitric acid solution volume are 1:
40g/ml。
The partial size D of natural flake graphite90It is 5-8 microns.
The temperature of magnetic agitation is 25 DEG C in step S1, and dry temperature is 80 DEG C.
The frequency of sonic oscillation is 20kHz, power 300W in step S2, and the processing time is 25-30 minutes, following implementations
Example is identical.
The quality of nano silica fume is 0.5g, pH value 6.2 in step S2.Nano silica fume, calgon with it is silane coupled
The mass ratio of agent is 100:2:9.At 120 ± 5 DEG C, the time was controlled at 4.5-5 hours for the temperature control being heated to reflux.It is silane coupled
Agent is KH550.
Drying temperature is 85 DEG C in step S3.
Pitch is 0.7g in step S4, and the ratio of pitch toluene solution studies on asphaltene amount and volume of toluene is 0.08g/ml.
The temperature of constant temperature drying is 60 DEG C in step S4.Dry in the shade is carried out in the environment of room temperature, no light, well-ventilated
It is dry.
Powder mixer uses MX series rotary mixing machine, Gu it is suitable for solid-mixing, and it is molten to be applicable in pitch toluene
Cladding of the liquid to NG/Si composite material.
The process conditions of pyrolysis are as follows: in N2Under protection, start to be warming up to 400 DEG C with the speed of 12 DEG C/min, keeps the temperature 5h, then
850 DEG C are warming up to the speed of 8 DEG C/min, keeps the temperature 1h, cooled to room temperature.In the present invention, room temperature refers to 23 ± 2 DEG C.
Embodiment 2
A kind of preparation method of pitch-coating silicon doping natural flake graphite negative electrode material, comprising the following steps:
S1: nitric acid solution is mixed with natural flake graphite, is reacted 3 hours under magnetic agitation, and filtering obtains the first sediment, washes
The first sediment is washed, dry, the natural flake graphite that obtains that treated；
S2: weighing nano silica fume, is added to absolute ethanol dissolution, adds calgon, after mixing evenly sonic oscillation, ice
Second acid for adjusting pH value is subsequently added into silane coupling agent, and magnetic agitation is heated to reflux, and sufficiently reacts, and is then centrifuged for de- ethyl alcohol, dries
It is dry, grinding, the nano silica fume that obtains that treated；
S3: will treated natural flake graphite nano silica fume mixes with treated, grind, first be added in gained mixture
Benzene, under nitrogen protection, 72 DEG C are stirred to react 5.5 hours, and filtering obtains the second sediment, wash the second sediment, dry, obtain
NG/Si composite material；
S4: NG/Si composite material being added in powder mixer, pitch toluene solution is poured into top spray device, opens top spray
Device, stirring mix NG/Si composite material and pitch toluene solution, and feeding is dried in the shade, then constant temperature drying, grind, pyrolysis,
Obtain product.
The concentration of nitric acid solution is 0.2mol/l, and the ratio of natural flake graphite quality and nitric acid solution volume is 1:42g/
ml。
The partial size D of natural flake graphite90It is 8-10 microns.
The temperature of magnetic agitation is 23 DEG C in step S1, and dry temperature is 82 DEG C.
The quality of nano silica fume is 0.6g, pH value 6.5 in step S2.
The mass ratio of nano silica fume, calgon and silane coupling agent is 100:3:10.Silane coupling agent is KH550.
Pitch is 0.8g in step S4, and the ratio of pitch toluene solution studies on asphaltene amount and volume of toluene is 0.09g/ml.
The temperature for dripping constant temperature drying in step S4 is 62 DEG C.
The process conditions of pyrolysis are as follows: in N2Under protection, start to be warming up to 420 DEG C with the speed of 13 DEG C/min, keeps the temperature 4h, then
830 DEG C are warming up to the speed of 7 DEG C/min, keeps the temperature 2h, cooled to room temperature.
Embodiment 3
A kind of preparation method of pitch-coating silicon doping natural flake graphite negative electrode material, comprising the following steps:
S1: nitric acid solution is mixed with natural flake graphite, is reacted 4 hours under magnetic agitation, and filtering obtains the first sediment, washes
The first sediment is washed, dry, the natural flake graphite that obtains that treated；
S2: weighing nano silica fume, is added to absolute ethanol dissolution, adds calgon, after mixing evenly sonic oscillation, ice
Second acid for adjusting pH value is subsequently added into silane coupling agent, and magnetic agitation is heated to reflux, and sufficiently reacts, and is then centrifuged for de- ethyl alcohol, dries
It is dry, grinding, the nano silica fume that obtains that treated；
S3: will treated natural flake graphite nano silica fume mixes with treated, grind, first be added in gained mixture
Benzene, under nitrogen protection, 75 DEG C are stirred to react 5 hours, and filtering obtains the second sediment, wash the second sediment, dry, obtain NG/
Si composite material；
S4: NG/Si composite material being added in powder mixer, pitch toluene solution is poured into top spray device, opens top spray
Device, stirring mix NG/Si composite material and pitch toluene solution, and feeding is dried in the shade, then constant temperature drying, grind, pyrolysis,
Obtain product.
The concentration of nitric acid solution is 0.15mol/l, and natural flake graphite quality and the ratio of nitric acid solution volume are 1:
45g/ml。
The partial size D of natural flake graphite90It is 10-12 microns.
The temperature of magnetic agitation is 28 DEG C in step S1, and dry temperature is 85 DEG C.
The quality of nano silica fume is 0.8g, pH value 6.3 in step S2.
The mass ratio of nano silica fume, calgon and silane coupling agent is 100:4:11.Silane coupling agent is KH550.
Pitch is 0.9g in step S4, and the ratio of pitch toluene solution studies on asphaltene amount and volume of toluene is 0.1g/ml.
The temperature of constant temperature drying is 65 DEG C in step S4.
The process conditions of pyrolysis are as follows: in N2Under protection, start to be warming up to 450 DEG C with the speed of 15 DEG C/min, keeps the temperature 3h, then
800 DEG C are warming up to the speed of 6 DEG C/min, keeps the temperature 3h, cooled to room temperature.
Embodiment 4
A kind of preparation method of pitch-coating silicon doping natural flake graphite negative electrode material of the present embodiment, specific steps and embodiment
1 is essentially identical, except that:
The concentration of nitric acid solution is 0.12mol/l, and the ratio of natural flake graphite quality and nitric acid solution volume is 1:46g/ml.
The partial size D of natural flake graphite90It is 12-15 microns.
The temperature of magnetic agitation is 23 DEG C in step S1, and dry temperature is 82 DEG C.
The quality of nano silica fume is 0.9g, pH value 6.2 in step S2.
The mass ratio of nano silica fume, calgon and silane coupling agent is 100:5:12.Silane coupling agent is KH560.
Pitch is 1.0g in step S4, and the ratio of pitch toluene solution studies on asphaltene amount and volume of toluene is 0.11g/ml.
The temperature of constant temperature drying is 65 DEG C in step S4.
The process conditions of pyrolysis are as follows: in N2Under protection, starts to be warming up to 430 DEG C with the speed of 14 DEG C/min, keeps the temperature 3.5h,
820 DEG C are warming up to the speed of 7.5 DEG C/min again, keeps the temperature 2.5h, cooled to room temperature.
Embodiment 5
A kind of preparation method of pitch-coating silicon doping natural flake graphite negative electrode material of the present embodiment, specific steps and embodiment
2 is essentially identical, except that:
The concentration of nitric acid solution is 0.1mol/l, and the ratio of natural flake graphite quality and nitric acid solution volume is 1:50g/ml.
The partial size D of natural flake graphite90It is 8-10 microns.
The temperature of magnetic agitation is 25 DEG C in step S1, and dry temperature is 85 DEG C.
The quality of nano silica fume is 0.7g, pH value 6.3 in step S2.
The mass ratio of nano silica fume, calgon and silane coupling agent is 100:2.5:10.Silane coupling agent is
KH560。
Pitch is 1.1g in step S4, and the ratio of pitch toluene solution studies on asphaltene amount and volume of toluene is 0.12g/ml.
The temperature of constant temperature drying is 63 DEG C in step S4.
The process conditions of pyrolysis are as follows: in N2Under protection, start to be warming up to 425 DEG C with the speed of 15 DEG C/min, keeps the temperature 4h, then
845 DEG C are warming up to the speed of 6.5 DEG C/min, keeps the temperature 1.5h, cooled to room temperature.
Embodiment 6
A kind of preparation method of pitch-coating silicon doping natural flake graphite negative electrode material of the present embodiment, specific steps and embodiment
1 is essentially identical, except that:
The concentration of nitric acid solution is 0.18mol/l, and the ratio of natural flake graphite quality and nitric acid solution volume is 1:44g/ml.
The quality of nano silica fume is 0.5g, the mass ratio of nano silica fume, calgon and silane coupling agent in step S2
For 100:3.5:10.5.
Pitch is 1.2g in step S4, and the ratio of pitch toluene solution studies on asphaltene amount and volume of toluene is 0.1g/ml.
Embodiment 7
A kind of preparation method of pitch-coating silicon doping natural flake graphite negative electrode material of the present embodiment, specific steps and embodiment
3 is essentially identical, except that:
The concentration of nitric acid solution is 0.23mol/l, and the ratio of natural flake graphite quality and nitric acid solution volume is 1:48g/ml.
The quality of nano silica fume is 0.6g, the mass ratio of nano silica fume, calgon and silane coupling agent in step S2
For 100:4.5:12.
Pitch is 1.0g in step S4, and the ratio of pitch toluene solution studies on asphaltene amount and volume of toluene is 0.12g/ml.
The mass ratio of pitch and natural flake graphite is 8:100.
Comparative example 1
A kind of preparation method of coating modification silicon doping natural flake graphite negative electrode material of this comparative example, specific steps and embodiment
1 is essentially identical, except that:
S4: NG/Si composite material is added in powder mixer, the ethanol solution of phenolic resin is poured into top spray device, is opened
Top spray device is opened, stirring mixes the ethanol solution of NG/Si composite material and phenolic resin, and 25 DEG C are stirred 6 hours, and temperature rises to
70 DEG C evaporate ethanol solution, and drying obtains product；Under nitrogen protection, by product 100 DEG C solidify 1 hour, then with 2 DEG C/
The heating rate of min is warming up to 900 DEG C and carbonizes 3 hours, and products therefrom is sieved after charing, obtains phenolic resin coated Si doping day
Right crystalline flake graphite；
Wherein, the mass ratio of phenolic resin and natural flake graphite is 9:100.
Comparative example 2
A kind of preparation method of pitch-coating silicon doping natural flake graphite negative electrode material of this comparative example, specific steps and embodiment
2 is essentially identical, except that:
In step S1, the concentration of nitric acid solution is 0.3mol/l, and natural flake graphite quality and the ratio of nitric acid solution volume are
1:55g/ml.
Comparative example 3
A kind of preparation method of pitch-coating silicon doping natural flake graphite negative electrode material of this comparative example, specific steps and embodiment
3 is essentially identical, except that:
Step S2-S4 is substituted by following step S2 '-S4 ':
Step S2 ': weighing nano silica fume, is added in toluene solution, adds silane coupling agent, is ultrasonically treated 20min, is formed equal
Even suspension；
Step S3 ': and then configuration pitch toluene solution, gained suspension is mixed to simultaneously ultrasound 50min with pitch toluene solution, is obtained
To mixed solution；
Step S4 ': weighing step S1 treated that natural flake graphite is added in powder mixer, and mixed solution is poured into top spray
In device, top spray device is opened, is stirred and evenly mixed, feeding is dried in the shade, then constant temperature drying, is ground, and pyrolysis obtains product.
The dosage and reality of nano silica fume, silane coupling agent, pitch toluene solution and natural flake graphite in the comparative example
Apply that example 3 is identical, and the mass volume ratio of nano silica fume and toluene solution is 0.8g:12ml in step S2 '.
Effect assessment
The negative electrode material of natural flake graphite, embodiment 1-3 and comparative example 1-3 preparation, binder are gathered into inclined difluoro second respectively
Alkene (PVDF) is mixed with conductive black according to mass ratio 85:10:5, be added N-Methyl pyrrolidone (NMP) afterwards grind 30min with
On mix it uniformly, then with scraper by it even spread on copper foil, scraper determine thickness be 0.2mm, then will be coated
Copper foil is put into baking oven to be taken out in 80 DEG C of drying 4h or more, and diaphragm is then depressed into 200 μ m thicks using roll squeezer, reuses blunderbuss
Diaphragm is punched into the round sheet material of diameter 10mm by son, then under vacuum conditions after 120 DEG C of drying 12h, its matter of precise
Amount.Battery assembly is completed in the glove box of applying argon gas, and metal lithium sheet is to electrode, vinyl carbonate (EC): dimethyl carbonate
(DMC): methyl ethyl carbonate (EMC)=1:1:1(volume ratio), the LiPF6 of 1mol/L+Solution is electrolyte, porous polypropylene diaphragm
For diaphragm, button cell is made.Stand after the completion of battery assembly makes electrolyte complete wetting diaphragm and electrode diaphragm for 24 hours, then into
Row battery testing.
Battery capacity cycle performance test method: assembled button cell is connected to LandCT2001A battery testing
Instrument is formulated on channel, carries out charge and discharge to battery using computer controlled constant stream.Charge and discharge stopping potential is 0.001-2.0V, is filled
10s is stood between discharge procedures switching, cycle-index is 50 times.Institute's sample can be directly obtained by battery testing software
Capacity, efficiency and cycle performance information, test result is as shown in table 1-1, table 1-2, table 1-3.
Table 1-1 battery performance test result (1)
。
By table 1-1 it is found that embodiment 1 and comparative example 1 are respectively adopted after natural flake graphite is modified by distinct methods,
It shows compared with the more excellent charging and discharging capacity of natural flake graphite and cycle performance, wherein the effect of embodiment 1 is more
Significantly, illustrate for the present invention, the modified effect of pitch-coating is more preferable.
Table 1-2 battery performance test result (2)
。
By table 1-2 it is found that different oxidation treatment methods is respectively adopted to natural flake graphite in embodiment 2 and comparative example 2
It is modified, test result is shown in the two in first discharge specific capacity value, and there are biggish difference, the oxidation processes of embodiment 2
Condition is apparently more suitable.
Table 1-3 battery performance test result (3)
。
By table 1-3 it is found that different doping and method for coating is respectively adopted to natural scale stone in embodiment 3 and comparative example 3
Ink is modified, and test result is shown: the first discharge specific capacity value of embodiment 3 is apparently higher than comparative example 3, and 50 circulations
Capacity retention rate it is also high compared with comparative example 3, show using the present invention doping and method for coating natural flake graphite is modified
Effect is more excellent.
Finally, it is stated that the above examples are only used to illustrate the technical scheme of the present invention and are not limiting, this field is common
Other modifications or equivalent replacement that technical staff makes technical solution of the present invention, without departing from technical solution of the present invention
Spirit and scope, be intended to be within the scope of the claims of the invention.
Claims (10)
1. a kind of preparation method of pitch-coating silicon doping natural flake graphite negative electrode material, which is characterized in that including following step
It is rapid:
S1: nitric acid solution is mixed with natural flake graphite, is reacted 2-4 hours under magnetic agitation, and filtering obtains the first sediment,
First sediment is washed, dry, the natural flake graphite that obtains that treated；
S2: weighing nano silica fume, is added to absolute ethanol dissolution, adds calgon, after mixing evenly sonic oscillation, ice
Second acid for adjusting pH value is subsequently added into silane coupling agent, and magnetic agitation is heated to reflux, and sufficiently reacts, and is then centrifuged for de- ethyl alcohol, dries
It is dry, grinding, the nano silica fume that obtains that treated；
S3: will treated the natural flake graphite with it is described treated that nano silica fume mixes, grind, in gained mixture
Toluene is added, under nitrogen protection, 70-75 DEG C is stirred to react 5-6 hours, and filtering obtains the second sediment, and it is heavy to wash described second
Starch, it is dry, obtain NG/Si composite material；
S4: the NG/Si composite material being added in powder mixer, pitch toluene solution is poured into top spray device, is opened
Top spray device, stirring mix the NG/Si composite material and pitch toluene solution, and feeding is dried in the shade, and then constant temperature drying, grinds
Mill, pyrolysis, obtains product.
2. the preparation method of pitch-coating silicon doping natural flake graphite negative electrode material according to claim 1, feature
Be: the concentration of the nitric acid solution is 0.1-0.25mol/l, the ratio of the natural flake graphite quality and nitric acid solution volume
Value is 1:(40-50) g/ml.
3. the preparation method of pitch-coating silicon doping natural flake graphite negative electrode material according to claim 1 or 2, special
Sign is: the partial size D of the natural flake graphite90It is 5-15 microns.
4. the preparation method of pitch-coating silicon doping natural flake graphite negative electrode material according to claim 3, feature
Be: the temperature of magnetic agitation described in step S1 is 23-28 DEG C, and the temperature of the drying is 80-85 DEG C.
5. the preparation method of pitch-coating silicon doping natural flake graphite negative electrode material according to claim 4, feature
Be: the pH value is 6.2-6.5.
6. the preparation method of pitch-coating silicon doping natural flake graphite negative electrode material according to claim 5, feature
Be: the mass ratio of the nano silica fume, calgon and silane coupling agent is 100:(2-5): (9-12).
7. the preparation method of pitch-coating silicon doping natural flake graphite negative electrode material according to claim 6, feature
Be: the ratio of the pitch toluene solution studies on asphaltene amount and volume of toluene is 0.08-0.12g/ml.
8. the preparation method of pitch-coating silicon doping natural flake graphite negative electrode material according to claim 7, feature
Be: the mass ratio of the pitch and natural flake graphite is (7-12): 100.
9. the preparation method of pitch-coating silicon doping natural flake graphite negative electrode material according to claim 1, feature
Be: the temperature of constant temperature drying described in step S4 is 60-65 DEG C.
10. the preparation method of pitch-coating silicon doping natural flake graphite negative electrode material according to claim 9, feature
It is: the process conditions of the pyrolysis are as follows: in N2Under protection, start to be warming up to 400-450 DEG C with the speed of 12-15 DEG C/min,
3-5h is kept the temperature, then is warming up to 800-850 DEG C with the speed of 6-8 DEG C/min, keeps the temperature 1-3h, cooled to room temperature.
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| CN113171880A (en) * | 2021-04-23 | 2021-07-27 | 中国矿业大学 | Flotation composite dispersant for lean and fine chalcopyrite and flotation method for lean and fine chalcopyrite |
| CN113644265A (en) * | 2021-07-27 | 2021-11-12 | 北京理工大学 | Preparation method of inorganic conformal-coated natural graphite negative electrode material |
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