CN109888263A - A kind of ferrous metasilicate lithium material of metal-carbon compound coating and its preparation method and application - Google Patents
A kind of ferrous metasilicate lithium material of metal-carbon compound coating and its preparation method and application Download PDFInfo
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Abstract
The present invention provides ferrous metasilicate lithium materials of a kind of metal-carbon compound coating and its preparation method and application, belong to lithium ion battery material technical field.The present invention provides a kind of ferrous metasilicate lithium materials of metal-carbon compound coating, comprising: ferrous metasilicate lithium core；Compound coating layer, the compound coating layer include carbon-coating and the nano metal that is embedded into the carbon-coating.The present invention is catalyzed using nano metal, has obtained the ferrous metasilicate lithium material of the metal-carbon compound coating of high graphitization, has 325mAhg under 0.2C current density‑1Capacity, raw material sources are extensive, at low cost, and have excellent electric conductivity and volumetric properties.
Description
Technical field
The present invention relates to lithium ion battery material technical fields, and in particular to a kind of silicic acid of metal-carbon compound coating is sub-
Iron lithium material and its preparation method and application.
Background technique
Since Nyten et al. has synthesized the ferrosilicon silicate of lithium (Li with electro-chemical activity2FeSiO4) since, different crystal forms
Li2FeSiO4It is found successively, wherein with P21/nAnd Pmn21The Li of space group structure2FeSiO4It is most commonly seen.Due in poly- yin
By [SiO between iron ion in ionic structure4] tetrahedron separates, electronics transfer is difficult in lattice, the Li of various crystal forms2FeSiO4
Band gap is big (about 3.0eV), electronic conductivity extremely low (about 10-14S.cm-1), unmodified Li2FeSiO4Usually only
It can be in first week release less than 150mAh.g-1Capacity.Conductive carbon coating and nanosizing can be effectively improved the conduction of positive electrode
Property and electro-chemical activity, and successfully solve polyanionic structure LiFePO4Conductivity problems.In recent years, both at home and abroad
Scholar uses similar strategy to carry out a large amount of improvement Li2FeSiO4The research work of performance, the strategy of carbon coating combination nanostructure
Discharge capacity is generally risen above into 160mAh.g-1, realize the reversible deintercalation of more than one lithium ion.However, even if low
Most results of study and Li of (about 0.1C) under current density condition2FeSiO4Theoretical capacity (332mAh.g-1) still phase
Away from very remote.
It is found when Zheng et al. and Fu et al. are using raman study carbon coating layer, Li2FeSiO4Electric conductivity and appearance
Performance is measured with clad graphitized carbon (sp2Carbon key) ratio raising and significantly improve, this benefit most from graphitized carbon tool
There is better electron conduction (referring to Fu R, Li Y, Yang H, Zhang Y, Cheng X, Improved Performance
of Li2FeSiO4/C Composite with Highly Rough Mesoporous Morphology.Journal of
the Electrochemical Society,2013.160(5):A3048-A3053).High graphitization journey is prepared in the prior art
Degree clad, which generally has CVD method and mixes previously prepared graphene oxide, restores two methods, if Yang et al. is using in advance
The graphene oxide and Li of preparation2FeSiO4Mixing, obtains high-graphitized carbon coating layer (referring to Yang after heat treatment
J,Hu L,Zheng J,He D,Tian L,Mu S,Pan F,Li2FeSiO4 nanorods bonded with graphene
for high performance batteries.Journal of Materials Chemistry A,2015.3(18):
9601-9608).But both methods cost of material is high, and preparation process is complicated, needs that Li is formerly prepared2FeSiO4Basis
On, then coat, degree of graphitization can not be regulated and controled；And discharge capacity is not high, it is difficult to meet industrial requirement.
Summary of the invention
The purpose of the present invention is to provide ferrous metasilicate lithium material of a kind of metal-carbon compound coating and preparation method thereof and
Using.The ferrous metasilicate lithium material of metal-carbon compound coating provided by the invention has excellent electric conductivity and volumetric properties, and
Raw material sources are extensive, preparation process is easy, and at low cost, degree of graphitization is controllable.
In order to achieve the above-mentioned object of the invention, the present invention the following technical schemes are provided:
The present invention provides a kind of ferrous metasilicate lithium materials of metal-carbon compound coating, comprising: ferrous metasilicate lithium core；
Compound coating layer, the compound coating layer include carbon-coating and the nano metal that is embedded into the carbon-coating.
Preferably, on the basis of the quality of the ferrous metasilicate lithium material of the metal-carbon compound coating, the ferrous metasilicate
The mass content of lithium core is greater than 90%, and the mass content of the nano metal is greater than 0.1%.
Preferably, the chemical formula of the ferrous metasilicate lithium material of the metal-carbon compound coating is Li2FeSiO4/C/Mx,
Middle M is Fe, Co or Ni, 0 < x < 0.2.
The present invention provides the preparation sides of the ferrous metasilicate lithium material of metal-carbon compound coating described in above-mentioned technical proposal
Method, comprising the following steps:
Lithium salt solution, iron salt solutions and teos solution are mixed, hydrolysis occurs, obtains the first mixed liquor；
First mixed liquor is mixed with citric acid solution, the first gel reaction occurs, obtains the second mixed liquor；
Second mixed liquor is mixed with metal salt solution, the second gel reaction occurs, obtains gel；
The gel is successively dried, pre-burning and sintering, obtains the ferrosilicon silicate of lithium material of metal-carbon compound coating
Material.
Preferably, the molar ratio of the molysite in the iron salt solutions and the citric acid in the citric acid solution is (1:0.5
~1:50).
Preferably, the temperature of the hydrolysis is 10~90 DEG C, and the time of the hydrolysis is 1~600min.
Preferably, the temperature of first gel reaction and second gel reaction independently is 40~99 DEG C, described
The time of first gel reaction and second gel reaction independently is 0.5~240h.
Preferably, the temperature of the drying is 50~200 DEG C, and the time of the drying is 0.5~240h；
The temperature of the pre-burning is 250~450 DEG C, and the time of the pre-burning is 0.1~1000h；
The temperature of the sintering is 550~1250 DEG C, and the time of the sintering is 0.5~240h.
Preferably, after the completion of the sintering, it is also preferable to include gained sintered product is cooled to room temperature, metal-carbon is obtained
The ferrous metasilicate lithium material of compound coating；The cooling rate is 0.001~40 DEG C/min.
The present invention also provides the ferrous metasilicate lithium material of metal-carbon compound coating described in above-mentioned technical proposal or above-mentioned skills
Ferrous metasilicate lithium material the answering in lithium ion battery for the metal-carbon compound coating that preparation method described in art scheme is prepared
With.
The present invention provides a kind of ferrous metasilicate lithium materials of metal-carbon compound coating, comprising: ferrous metasilicate lithium core；
Compound coating layer, the compound coating layer include carbon-coating and the nano metal that is embedded into the carbon-coating.The present invention utilizes nanometer
Metal catalytic has obtained the ferrous metasilicate lithium material of the metal-carbon compound coating of high graphitization, has had under 0.2C current density
325mAh·g-1Capacity, raw material sources are extensive, at low cost, and have excellent electric conductivity and volumetric properties.
The present invention provides the preparation methods of the ferrous metasilicate lithium material of the metal-carbon compound coating, including following step
It is rapid: lithium salt solution, iron salt solutions and teos solution being mixed, hydrolysis occurs, obtains the first mixed liquor；It will be described
First mixed liquor is mixed with citric acid solution, and the first gel reaction occurs, obtains the second mixed liquor；By second mixed liquor with
Metal salt solution mixing, occurs the second gel reaction, obtains gel；The gel is successively dried, pre-burning and sintering, is obtained
To the ferrous metasilicate lithium material of metal-carbon compound coating.The present invention uses gel method, using ethyl orthosilicate as silicon source, with lemon
Acid is that carbon source can directly obtain the ferrous metasilicate of the metal-carbon compound coating of high graphitization under the catalytic action of metal salt
Lithium material is coated again without first preparing ferrosilicon silicate of lithium, and degree of graphitization is controllable, and the operation is more convenient, safety and environmental protection,
It is suitable for industrialized production.
Detailed description of the invention
Fig. 1 is Li prepared by the embodiment of the present invention 12FeSiO4/C/Fe0.1XRD spectra；
Fig. 2 is Li prepared by the embodiment of the present invention 22FeSiO4/C/Fe0.1XRD spectra；
Fig. 3 is Li prepared by the embodiment of the present invention 32FeSiO4/C/Fe0.1XRD spectra；
Fig. 4 is Li prepared by the embodiment of the present invention 42FeSiO4/C/Fe0.2XRD spectra；
Fig. 5 is the Li of comparative example preparation2FeSiO4The XRD spectra of/C；
Fig. 6 is Li prepared by the embodiment of the present invention 12FeSiO4/C/Fe0.1Raman spectrogram；
Fig. 7 is Li prepared by the embodiment of the present invention 22FeSiO4/C/Fe0.1Raman spectrogram；
Fig. 8 is Li prepared by the embodiment of the present invention 32FeSiO4/C/Fe0.1Raman spectrogram；
Fig. 9 is the Li of comparative example preparation2FeSiO4The Raman spectrogram of/C；
Figure 10 is the Li of comparative example preparation2FeSiO4Discharge curve of/the C under 0.2C current density；
Figure 11 is Li prepared by the embodiment of the present application 12FeSiO4/C/Fe0.1Discharge curve under 0.2C current density；Its
In, 1 recycled for first week；2 recycle for second week；3 be third Zhou Xunhuan；4 recycle for 4th week；5 be the 5th Zhou Xunhuan；
Figure 12 is Li prepared by the embodiment of the present invention 52FeSiO4/C/Ni0.1XRD spectra；
Figure 13 is Li prepared by the embodiment of the present invention 62FeSiO4/C/Co0.1XRD spectra.
Specific embodiment
The present invention provides a kind of ferrous metasilicate lithium materials of metal-carbon compound coating, comprising: ferrous metasilicate lithium core；
Compound coating layer, the compound coating layer include carbon-coating and the nano metal that is embedded into the carbon-coating.In the present invention, described
The partial size of the ferrous metasilicate lithium material of metal-carbon compound coating is preferably 20~500nm, more preferably 40~60nm, most preferably
For 50nm；The thickness of the compound coating layer is preferably 1~100nm, more preferably 3~10nm, most preferably 5nm.In this hair
In bright, the forming process of the compound coating layer specifically: nano-metal particle outside ferrous metasilicate particle with carbon-coating phase mutual connection
Touching, during follow-up sintering, nano-metal particle absorbs the amorphous carbon of the clad of raw material, then in temperature-fall period
In lamellar graphitic carbon be precipitated from nano-metal particle be coated on ferrous metasilicate particle surface, nano-metal particle and silicon again
Sour ferrous iron particle is bound up by graphited carbon coating layer.
In the present invention, on the basis of the quality of the ferrous metasilicate lithium material of the metal-carbon compound coating, the silicic acid
The mass content of ferrous lithium core is preferably greater than 90%, more preferably 98%；The mass content of the nano metal is preferably greater than
0.1%, more preferably 2%.In the present invention, the partial size of the nano metal is preferably 5~50nm, more preferably 15~
25nm, most preferably 20nm.
In the present invention, the chemical formula of the ferrous metasilicate lithium material of the metal-carbon compound coating is preferably Li2FeSiO4/
C/Mx, wherein M is preferably Fe, Co or Ni, 0 < x < 0.2；More preferably 0.1≤x < 0.2.
The present invention provides the preparation sides of the ferrous metasilicate lithium material of metal-carbon compound coating described in above-mentioned technical proposal
Method, comprising the following steps:
Lithium salt solution, iron salt solutions and teos solution are mixed, hydrolysis occurs, obtains the first mixed liquor；
First mixed liquor is mixed with citric acid solution, the first gel reaction occurs, obtains the second mixed liquor；
Second mixed liquor is mixed with metal salt solution, the second gel reaction occurs, obtains gel；
The gel is successively dried, pre-burning and sintering, obtains the ferrosilicon silicate of lithium material of metal-carbon compound coating
Material.
The present invention mixes lithium salt solution, iron salt solutions and teos solution, and hydrolysis occurs, and it is mixed to obtain first
Close liquid.
In the present invention, the concentration of the lithium salt solution is preferably 1~3mol/L, more preferably 2.85mol/L；The lithium
The solvent of salting liquid is preferably the mixed liquor of dehydrated alcohol and water, the volume ratio of the dehydrated alcohol and water be preferably 1:(1~
0.2), more preferably 3:2；Lithium salts is preferably lithium nitrate or lithium acetate.In a specific embodiment of the present invention using lithium nitrate as
The lithium source of ferrous metasilicate lithium core is conducive to dissolve in the mixed liquor of water and ethyl alcohol.
In the present invention, the concentration of the iron salt solutions is preferably 0.5~3mol/L, more preferably 2.85~3mol/L；
The solvent of the iron salt solutions is preferably the mixed liquor of dehydrated alcohol and water, and the volume ratio of the dehydrated alcohol and water is preferably
(0.5~10): 1, more preferably 3:2；Molysite is preferably ferric nitrate, iron chloride, ferric acetate or ferric oxalate.The present invention is made with molysite
For the source of iron of ferrous metasilicate lithium core, be conducive to dissolve in the mixed liquor of water and ethyl alcohol.
In the present invention, the concentration of the teos solution is preferably 0.5~1.5mol/L, more preferably
1.425mol/L；The solvent of the teos solution is preferably the mixed liquor of dehydrated alcohol and water, the dehydrated alcohol with
The volume ratio of water is preferably (0.5~10): 1, more preferably 3:1.In the present invention, the preparation side of the teos solution
Formula is preferably to instill ethyl orthosilicate in the mixed liquor of dehydrated alcohol and water, and the speed of the dropwise addition is preferably 0.05mL/
min.The present invention is conducive in the mixed liquor of water and ethyl alcohol uniformly using ethyl orthosilicate as the silicon source of ferrous metasilicate lithium core
Mixing.
In the present invention, the lithium salts in the lithium salt solution, the molysite in iron salt solutions and the teos solution
In ethyl orthosilicate molar ratio be preferably (1.9~2.1): 1:1, more preferably 2:1:1.
In the present invention, lithium salt solution and iron salt solutions are preferably added sequentially to teos solution by the mixing
In mixed, the present invention use above-mentioned order of addition, it is therefore an objective to inhibit Li2SiO3The appearance of equal impurity.In the present invention, institute
It states mixing preferably to carry out under agitation, the speed of the stirring is preferably 10~800r/min, more preferably 50~100r/
Min, most preferably 60r/min.
In the present invention, the temperature of the hydrolysis is preferably 10~90 DEG C, and more preferably 30 DEG C；The hydrolysis
Time be preferably 1~600min, more preferably 40~300min, most preferably 60min.
After obtaining the first mixed liquor, the present invention mixes first mixed liquor with citric acid solution, and the first gel occurs
Reaction, obtains the second mixed liquor.In the present invention, the concentration of the citric acid solution is preferably 0.5~40mol/L, more preferably
For 4.285mol/mL；The solvent of the citric acid solution is preferably the mixed liquor of dehydrated alcohol and water, the dehydrated alcohol and water
Volume ratio be preferably (0.5~10): 1, more preferably 3:2.The present invention is using citric acid as the silicic acid of metal-carbon compound coating
The carbon source of ferrous lithium material is conducive to control nano metal and is uniformly distributed, and obtains carbon-coating.
In the present invention, the molar ratio of the molysite in the iron salt solutions and the citric acid in the citric acid solution is preferred
For (0.2~10): 3, more preferably 1:3, the effect that the present invention limits above-mentioned amount ratio is to prevent gel uneven, and provide foot
Enough carbon atoms obtain nano-metal particle for subsequent carbon-thermal reduction.
In the present invention, the mixing preferably carries out under agitation, and the speed of the stirring is preferably 10~800r/
Min, more preferably 50~100r/min, most preferably 60r/min.In the present invention, first gel reaction is preferably returning
It is carried out under the conditions of stream；The temperature of first gel reaction is preferably 40~99 DEG C, more preferably 60~90 DEG C, most preferably 80
℃；The time of first gel reaction is preferably 0.5~240h, more preferably 1~10h, most preferably 5h.Described first
In gel reaction process, condensation reaction occurs in the solution for lithium salts, molysite, ethyl orthosilicate, microcosmic under citric acid effect to receive
Aggregation, which is formed, in rice region meets Li2FeSiO4The micelle of chemical element metering ratio.
After obtaining the second mixed liquor, the present invention mixes second mixed liquor with metal salt solution, and the second gel occurs
Reaction, obtains gel.In the present invention, the concentration of the metal salt solution is preferably 0.01~1mol/L, more preferably
0.4mol/L；The solvent of the metal salt solution is preferably the mixed liquor of dehydrated alcohol and water, the body of the dehydrated alcohol and water
Product is than being preferably (0.5~10): 1, more preferably 3:2.Metal salt is preferably nitric acid metal salt, chlorination metal salt, metal acetate
Salt or oxalic acid metal salt, more preferably ferric nitrate, ferrous oxalate, cobalt nitrate, cobalt acetate, cobalt oxalate, nickel acetate, nickel oxalate or nitre
Sour nickel.In the present invention, the molar ratio of the metal salt in the metal salt solution and the molysite in the iron salt solutions is preferably
(0.01~10): 1, more preferably 0.1:1.
In the present invention, the metal salt solution is preferably added in second mixed liquor by the mixing mixes
It closes, the mixing preferably carries out under agitation, and the speed of the stirring is preferably 10~800r/min, more preferably 50~
100r/min, most preferably 60r/min.In the present invention, second gel reaction preferably carries out under reflux conditions；It is described
The temperature of second gel reaction is preferably 40~99 DEG C, more preferably 60~90 DEG C, most preferably 80 DEG C；Second gel is anti-
The time answered is preferably 0.5~240h, more preferably 1~10h, most preferably 19h.The present invention is carrying out the first gel reaction
Afterwards, the purpose that metal salt solution is added again into the second mixed liquor of gained is to form the region of metal ion enrichment, after being conducive to
Phase forms nano-metal particle.
After obtaining gel, the gel is successively dried the present invention, pre-burning and sintering, obtains the compound packet of metal-carbon
The ferrous metasilicate lithium material covered.In the present invention, the temperature of the drying is preferably 50~200 DEG C, and more preferably 70~90 DEG C,
Most preferably 80 DEG C；The time of the drying is preferably 0.5~240h, more preferably 20~30h, most preferably for 24 hours.The present invention
By drying and removing the moisture in gel, it help to obtain the uniform product of ingredient.
In the present invention, the pre-burning preferably carries out in air；The temperature of the pre-burning is preferably 250~450 DEG C, more
Preferably 300~400h, most preferably 250 DEG C；The time of the pre-burning is preferably 0.1~1000h, more preferably 60~90h,
Most preferably 80h.The present invention help to obtain residual carbon for subsequent cladding by pre-burning.
In the present invention, the sintering preferably carries out under the conditions of protective atmosphere, and the protective atmosphere is preferably argon
Gas atmosphere, nitrogen atmosphere or reducing atmosphere, more preferably argon atmosphere；The pressure of the sintering is preferably 0.001~1MPa,
More preferably 0.2Mpa；The temperature of the sintering is preferably 550~1250 DEG C, more preferably 700~800 DEG C, most preferably 750
℃；The time of the sintering is preferably 0.5~240h, more preferably 8~12h, most preferably 10h.In specific reality of the invention
It applies in example and is sintered under the above conditions by limiting, nanometer pure iron particle and a Li can be obtained simultaneously2FeSiO4Particle.
The present invention, it is also preferable to include gained sintered product is cooled to room temperature, obtains metal-carbon after the completion of the sintering
The ferrous metasilicate lithium material of compound coating.In the present invention, the cooling rate is preferably 0.001~40 DEG C/min, more preferably
For 1~30 DEG C/min, most preferably 2~5 DEG C/min.It is in order to by amorphous carbon that the present invention, which limits cooling rate in above range,
It is converted into graphitized carbon.In the present invention, the room temperature refers to 10~200 DEG C.The present invention can be controlled by adjusting rate of temperature fall
The degree of graphitization of carbon-coating processed.
The present invention also provides the ferrous metasilicate lithium material of metal-carbon compound coating described in above-mentioned technical proposal or above-mentioned skills
Ferrous metasilicate lithium material the answering in lithium ion battery for the metal-carbon compound coating that preparation method described in art scheme is prepared
With the present invention is preferably using the ferrous metasilicate lithium material of the metal-carbon compound coating as the positive electrode of lithium ion battery.This
Invent provide metal-carbon compound coating ferrous metasilicate lithium material discharge capacity with higher (theoretical capacity >
330mAh.g-1), it can be improved the discharge performance of lithium ion battery.
Below in conjunction with the embodiment in the present invention, the technical solution in the present invention is clearly and completely described.It is aobvious
So, described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.Based on the reality in the present invention
Example is applied, every other embodiment obtained by those of ordinary skill in the art without making creative efforts all belongs to
In the scope of protection of the invention.
Embodiment 1
0.02mol ethyl orthosilicate is instilled into 14mL by dehydrated alcohol and water (volume with the rate of addition of 0.05mL/min
Than 3:1) composition mixed liquor in, obtain teos solution；
0.04mol lithium nitrate is dissolved in the mixed liquor that 14mL is made of dehydrated alcohol and water (volume ratio 3:2), is obtained
Lithium nitrate solution；
0.04mol ferric nitrate is dissolved in the mixed liquor that 14mL is made of dehydrated alcohol and water (volume ratio 3:2), is obtained
First iron nitrate solution；
0.06mol citric acid is dissolved in the mixed liquor that 14mL is made of dehydrated alcohol and water (volume ratio 3:2), is obtained
Citric acid solution；
0.002mol ferric nitrate is dissolved in the mixed liquor that 5mL is made of dehydrated alcohol and water (volume ratio 3:2), is obtained
Second iron nitrate solution；
The lithium nitrate solution, the first iron nitrate solution are sequentially added in sequence in the teos solution,
Hydrolysis occurs under the conditions of the mixing speed of 60r/min, 30 DEG C, the time of the hydrolysis is 60min, obtains first
Mixed liquor；
First mixed liquor is added in the citric acid solution, the mixing speed of 60r/min, 80 DEG C of conditions next time
First gel reaction occurs for stream, and the time of first gel reaction is 5h, obtains the second mixed liquor；
Second iron nitrate solution is added in above-mentioned second mixed liquor, and continues return stirring 19h, it is solidifying to occur second
Glue reaction, obtains gel；
By the gel, drying for 24 hours, obtains presoma under the conditions of 80 DEG C；Then by the presoma in air, 250
Pre-burning 80h under the conditions of DEG C, then the pre-burning product is placed in argon atmosphere, setting pressure is 0.2MPa, in 750 DEG C of conditions
Then the sintered product is cooled to room temperature (specific 25 DEG C) with the cooling rate of 2 DEG C/min, obtains metal-by lower sintering 10h
The ferrous metasilicate lithium material Li of carbon compound coating2FeSiO4/C/Fe0.1, the Li2FeSiO4Partial size be 50nm；Wherein, compound
Clad with a thickness of 2~5nm, the partial size of Nanoscale Iron is 20nm in the compound coating layer.
Embodiment 2
It is essentially identical with the preparation method of embodiment 1, it the difference is that only and be adjusted to calcined temperature by " 250 DEG C "
" 350 DEG C " obtain the ferrous metasilicate lithium material Li of metal-carbon compound coating2FeSiO4/C/Fe0.1, the Li2FeSiO4Grain
Diameter is 60nm；Wherein, compound coating layer with a thickness of 2~5nm, the partial size of Nanoscale Iron is 30nm in the compound coating layer.
Embodiment 3
It is essentially identical with the preparation method of embodiment 1, the difference is that only by the cooling rate of sintered product by " 2 DEG C/
Min " is adjusted to " 20 DEG C/min ", obtains the ferrous metasilicate lithium material Li of metal-carbon compound coating2FeSiO4/C/Fe0.1, described
Li2FeSiO4Partial size be 50nm；Wherein, compound coating layer with a thickness of 5nm, the partial size of Nanoscale Iron in the compound coating layer
For 25nm.
Embodiment 4
It is essentially identical with the preparation method of embodiment 1, it the difference is that only the concentration for increasing the second iron nitrate solution,
The concentration of second iron nitrate solution is 0.8mol/L, obtains the ferrous metasilicate lithium material of metal-carbon compound coating
Li2FeSiO4/C/Fe0.2, the Li2FeSiO4/C/Fe0.2Partial size be 50nm；Wherein, compound coating layer with a thickness of 2~
5nm, the partial size of Nanoscale Iron is 20~40nm in the compound coating layer.
Embodiment 5
It is essentially identical with the preparation method of embodiment 1, it the difference is that only and the second iron nitrate solution is substituted for nitric acid
The concentration of nickel solution, the nickel nitrate solution is 0.4mol/L, obtains the ferrous metasilicate lithium material of metal-carbon compound coating
Li2FeSiO4/C/Ni0.1, the Li2FeSiO4/C/Ni0.1Partial size be 50nm；Wherein, compound coating layer with a thickness of 5nm,
The partial size of Nanoscale Iron is 20nm in the compound coating layer.
Embodiment 6
It is essentially identical with the preparation method of embodiment 1, it the difference is that only and the second iron nitrate solution is substituted for nitric acid
The concentration of cobalt liquor, the nickel nitrate solution is 0.4mol/L, obtains the ferrous metasilicate lithium material of metal-carbon compound coating
Li2FeSiO4/C/Co0.1, the Li2FeSiO4/C/Co0.1Partial size be 50nm；Wherein, compound coating layer with a thickness of 5nm,
The partial size of Nanoscale Iron is 20nm in the compound coating layer.
Comparative example
Carbon coating ferrous metasilicate lithium material is prepared, preparation method is specially to omit that the second nitre is prepared and added in embodiment 1
Sour ferrous solution carries out the step of the second gel reaction, obtains Li2FeSiO4/C。
Test example
The carbon coating of ferrous metasilicate lithium material and comparative example preparation to the metal-carbon compound coating of Examples 1 to 6 preparation
Ferrous metasilicate lithium material is characterized, and gained XRD spectra is shown in Fig. 1~5 and Figure 12~13.It can be seen by Fig. 1~5 and Figure 12~13
Out, the Li that Examples 1 to 6 is prepared2FeSiO4/C/Fe0.1XRD spectra in have apparent Li2FeSiO4Diffraction maximum and gold
Belong to the diffraction maximum of iron；Li prepared by embodiment 42FeSiO4/C/Fe0.2XRD spectra in pure iron content it is higher, Li2FeSiO4Spread out
It is unobvious to penetrate peak；The Li that embodiment 5 is prepared2FeSiO4/C/Ni0.1XRD spectra in have apparent Li2FeSiO4Diffraction maximum
With the diffraction maximum of metallic nickel；The Li that embodiment 6 is prepared2FeSiO4/C/Co0.1XRD spectra in have apparent Li2FeSiO4
The diffraction maximum of diffraction maximum and metallic cobalt；The Li of comparative example preparation2FeSiO4There is no metal simple-substance in/C.
The carbon coating of ferrous metasilicate lithium material and comparative example preparation to the metal-carbon compound coating of Examples 1 to 3 preparation
The degree of graphitization of ferrous metasilicate lithium material is detected, and gained Raman spectrogram is shown in Fig. 6~9.It can be seen from Fig. 6~9 originally
Li prepared by inventive embodiments 12FeSiO4/C/Fe0.1Degree of graphitization be 76.6%, embodiment 2 prepare Li2FeSiO4/
C/Fe0.1Degree of graphitization be 73.5%, embodiment 3 prepare Li2FeSiO4/C/Fe0.1Degree of graphitization be 66%, and
The Li of comparative example preparation2FeSiO4The degree of graphitization of/C is only 52%, illustrates that the application significantly improves ferrosilicon silicate of lithium cladding
The degree of graphitization of layer is conducive to improve electric conductivity and volumetric properties.
The Li that embodiment 1 is obtained2FeSiO4/C/Fe0.1The Li obtained with comparative example2FeSiO4The discharge capacity of/C carries out
Detection, tests its discharge curve under 0.2C current density, acquired results are shown in Figure 10~11.It can be seen from Figure 10~11
The Li of comparative example preparation2FeSiO4/ C peak capacity under 0.2C current density is only 270mAhg-1, prepared by the present invention
Li2FeSiO4/C/Fe0.1Peak capacity under 0.2C current density is up to 325mAhg-1, significantly improve discharge capacity.
The above is only a preferred embodiment of the present invention, it is noted that for the ordinary skill people of the art
For member, various improvements and modifications may be made without departing from the principle of the present invention, these improvements and modifications are also answered
It is considered as protection scope of the present invention.
Claims (10)
1. a kind of ferrous metasilicate lithium material of metal-carbon compound coating characterized by comprising
Ferrous metasilicate lithium core；
Compound coating layer, the compound coating layer include carbon-coating and the nano metal that is embedded into the carbon-coating.
2. the ferrous metasilicate lithium material of metal-carbon compound coating according to claim 1, which is characterized in that with the gold
On the basis of the quality of category-carbon compound coating ferrous metasilicate lithium material, the mass content of the ferrous metasilicate lithium core is greater than
90%, the mass content of the nano metal is greater than 0.1%.
3. the ferrous metasilicate lithium material of metal-carbon compound coating according to claim 1 or 2, which is characterized in that the gold
The chemical formula of category-carbon compound coating ferrous metasilicate lithium material is Li2FeSiO4/C/Mx, wherein M is Fe, Co or Ni, 0 < x <
0.2。
4. the preparation method of the ferrous metasilicate lithium material of any one of claims 1 to 3 metal-carbon compound coating, feature
It is, comprising the following steps:
Lithium salt solution, iron salt solutions and teos solution are mixed, hydrolysis occurs, obtains the first mixed liquor；
First mixed liquor is mixed with citric acid solution, the first gel reaction occurs, obtains the second mixed liquor；
Second mixed liquor is mixed with metal salt solution, the second gel reaction occurs, obtains gel；
The gel is successively dried, pre-burning and sintering, obtains the ferrous metasilicate lithium material of metal-carbon compound coating.
5. the preparation method according to claim 4, which is characterized in that molysite and the citric acid in the iron salt solutions
The molar ratio of citric acid in solution is (1:0.5~1:50).
6. the preparation method according to claim 4, which is characterized in that the temperature of the hydrolysis is 10~90 DEG C, institute
The time for stating hydrolysis is 1~600min.
7. the preparation method according to claim 4, which is characterized in that first gel reaction and second gel are anti-
The temperature answered independently is 40~99 DEG C, and the time of first gel reaction and second gel reaction independently is 0.5
~240h.
8. the preparation method according to claim 4, which is characterized in that the temperature of the drying is 50~200 DEG C, described dry
The dry time is 0.5~240h；
The temperature of the pre-burning is 250~450 DEG C, and the time of the pre-burning is 0.1~1000h；
The temperature of the sintering is 550~1250 DEG C, and the time of the sintering is 0.5~240h.
9. the preparation method according to claim 4 or 8, which is characterized in that after the completion of the sintering, it is also preferable to include by institute
It obtains sintered product and is cooled to room temperature, obtain the ferrous metasilicate lithium material of metal-carbon compound coating；The cooling rate is 0.001
~40 DEG C/min.
10. the ferrous metasilicate lithium material or claim 4~9 of the described in any item metal-carbon compound coatings of claims 1 to 3
Ferrous metasilicate lithium material the answering in lithium ion battery for the metal-carbon compound coating that any one preparation method is prepared
With.
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| CN106252588A (en) * | 2016-09-14 | 2016-12-21 | 湘潭大学 | The spherical Li of lithium ion battery that a kind of size is controlled2feSiO4the preparation method of/C positive electrode material |
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| CN1649189A (en) * | 2004-12-29 | 2005-08-03 | 浙江大学 | Method for preparing carbon coated lithium ferrous phosphate composite material including metal conductive agent |
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| CN105895872A (en) * | 2016-04-13 | 2016-08-24 | 杨仲英 | Preparation method of coated lithium iron silicate composite material |
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