CN109256540A - The method and anode modified material of lanthanum sesquioxide are coated on the surface of the material - Google Patents
The method and anode modified material of lanthanum sesquioxide are coated on the surface of the material Download PDFInfo
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- CN109256540A CN109256540A CN201810942745.8A CN201810942745A CN109256540A CN 109256540 A CN109256540 A CN 109256540A CN 201810942745 A CN201810942745 A CN 201810942745A CN 109256540 A CN109256540 A CN 109256540A
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- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
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- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
- H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
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- H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
- H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
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Abstract
The present invention provides a kind of method for coating lanthanum sesquioxide on the surface of the material and the anode modified materials prepared with this method, comprising the following steps: is successively distributed in solvent material to be covered and lanthanum salt, obtains the first mixed liquor；Appropriate complexing agent is taken, dissolution obtains enveloping agent solution；Enveloping agent solution is added dropwise in the first mixed liquor, after heated stirring, precipitating is obtained by filtration, cleaning collects and precipitates and be dried and be heat-treated to it, and the material that surface is coated with lanthanum sesquioxide can be obtained.In the present invention, after anode material for lithium-ion batteries, nano-carbon material or aromatic amine high molecular compound etc. are mixed with lanthanum salt, the La that is formed under the action of complexing agent3+Complex precipitate is dispersed in the surface of material to be covered, after Overheating Treatment, so that be coated on material surface to be covered is the La of stable structure2O3, the preparation method simple process and can guarantee La2O3Uniformly it is deposited in material surface to be covered.
Description
Technical field
The present invention relates to technical field of lithium ion, in particular to a kind of three oxidation two of cladding on the surface of the material
The method of lanthanum and the anode modified material prepared with this method.
Background technique
Today's society economic development is very rapid, and people's lives level is continuously improved, need of the human society for the energy
It asks and also increasingly rises therewith.However the non-renewable fossil energy such as coal, petroleum, natural gas has been far from satisfying people day
The energy demand that benefit increases, and problem of environmental pollution caused by combustion of fossil fuels is also got worse, and wherein PM2.5 most draws
People gazes at, and many city hazes are serious, therefore the main task of today's society is to find and develop high-efficiency environment friendly sustainable development
New energy.The device that chemical energy can be converted to electric energy is known as electrochmical power source, has been subjected to the wide of many researchers
General concern.Wherein, secondary cell first entered the public visual field in 1899, is a kind of novel electrochmical power source, realizes electricity
Can be with the reversible transformation of chemical energy, secondary cell is at low cost, specific energy is high, high-efficient environmentally friendly and cycle performance
The advantages that good, is therefore widely used in social life every field, pushes the fast development of social economy.
Representative secondary cell has lead-acid accumulator, ickel-cadmium cell, nickel-metal hydride battery and lithium ion battery, relative to
Other secondary cells, lithium ion battery is because operating voltage is high, energy density is big, good rate capability, long service life and right
Environmental-friendly equal many merits, are current comprehensive performance secondary chemical sources of electric energy the most excellent.In recent years, lithium ion battery is answered
More and more extensive with field, with the development of electric vehicle (EV) and hybrid electric vehicle (HEV), high specific energy and high power have become the present
The important directions of Study on Li-ion batteries and development afterwards.Key component of the positive electrode as lithium ion battery is studied and is opened
Hair seems especially urgent.
Lithium ion battery LiNi1/3Co1/3Mn1/3O2Tertiary cathode material specific discharge capacity is high, but during circulation
Its capacity attenuation is serious, in the prior art by oxide coated to alleviate capacity attenuation phenomenon on it, but often occurs
Structural unstable adverse consequences.
Summary of the invention
In consideration of it, prepared the invention proposes a kind of method for coating lanthanum sesquioxide on the surface of the material and with this method
Anode modified material, it is intended to solve existing lithium ion battery LiNi1/3Co1/3Mn1/3O2Tertiary cathode modified material electrochemistry
The poor problem of performance.
Specifically, first aspect present invention proposes a kind of method for coating lanthanum sesquioxide on the surface of the material, including with
Lower step:.
(1) material to be covered and lanthanum salt are successively distributed in solvent, obtain the first mixed liquor.
Specifically, material to be covered is anode material for lithium-ion batteries, nano-carbon material or aromatic amine high molecular
Close object.Anode material for lithium-ion batteries can select binary or ternary lithium ion cell positive material, such as LiCoO2、LiMn2O4、
LiFePO4Or LiNi1/3Co1/3Mn1/3O2.Nano-carbon material can select carbon nanotube, carbon nano-fiber or nano carbon microsphere etc.；Virtue
Fragrant amine high-molecular compound can select the stronger substance of the electric conductivity such as polyaniline.I.e. lanthanum sesquioxide can be coated on lithium from
Sub- cell positive material LiCoO2、 LiMn2O4、LiFePO4、LiNi1/3Co1/3Mn1/3O2, carbon nanotube, carbon nano-fiber, nanometer
On the materials such as carbon ball or polyaniline.The embodiment of the present invention is with anode material for lithium-ion batteries LiNi1/3Co1/3Mn1/3O2For it is (pure
Phase LiNi1/3Co1/3Mn1/3O2For commercial product, without limitation to its source), lanthanum sesquioxide is coated on its surface.
Lanthanum salt can be at least one for lanthanum nitrate, lanthanum acetate and lanthanum chloride.Preferably, lanthanum salt can be lanthanum nitrate, valence
Lattice are cheap, are easily obtained, and with the complex reaction of complexing agent can be carried out more thoroughly, the by-product of reaction is less.Specifically
When implementation, ethyl alcohol can be selected as solvent, material to be covered and lanthanum salt are sequentially added in ethyl alcohol and sufficiently dissolved, favorably
Organic waste materials after reducing reaction；It can be adequately molten by lanthanum salt and material to be covered by the way of ultrasonic vibration, stirring
Solution is in ethanol.
(2) appropriate complexing agent is taken, dissolution obtains enveloping agent solution.
Specifically, complexing agent can be urea, five second of ethylenediamine tetra-acetic acid, hydroxyl ethylenediamine tetra-acetic acid or diethylenetriamine
Acid.Preferably, complexing agent is urea.When it is implemented, ethyl alcohol can also be selected as solvent, urea is added in ethyl alcohol and is carried out
Sufficiently dissolution obtains enveloping agent solution.
In the present embodiment, lanthanum salt and the mass ratio of material to be covered can be determined according to actual needs.Lanthanum salt and institute
The mass ratio for stating complexing agent is 1.08:(1.15~2.69)；Preferably 1.08:1.92.
(3) enveloping agent solution is added dropwise in first mixed liquor, after heated stirring, precipitating is obtained by filtration,
It cleans, collect the precipitating and it is dried and is heat-treated, the material that surface is coated with lanthanum sesquioxide can be obtained.
Specifically, since the temperature needed for reacting is unsuitable excessively high, while in order to enable reaction system temperature-controllable, can
It is heated in a manner of using heating water bath, it is preferred that the temperature of heating water bath is (60-90) DEG C, further preferably
(70-80) DEG C, more preferably 80 DEG C.When it is implemented, bath temperature can be made to be maintained at preset range by the way that thermocouple is added
It is interior.
Using urea as complexing agent, using lanthanum nitrate as lanthanum salt, specific reaction equation is as follows:
The hydrolysis of urea dissolution: CO (NH2)2+H2O=CO2+2NH3
Hydrolysis of urea product NH3With reacting for water: NH3+H2O=HN4 ++OH-
La3+With OH-Reaction: 3OH-+La(NO3)3=La (OH)3+3NO3 -
Total reaction process are as follows: 2La (NO3)3+3CO(NH2)2+9H2O=2La (OH)3+6NO3 -+6HN4 + +3CO2
Further, it is all added to the enveloping agent solution and starts timing, isothermal reaction into first mixed liquor
Precipitating is obtained by filtration in the second obtained mixed liquor by (10-16) h, and washing collects precipitating, and precipitating is dried at room temperature for, obtains
The material of lanthanum hydroxide is coated with to surface.In the step, it is preferred that the reaction time can be 12h.
Further, the surface is coated with to the material of lanthanum hydroxide at (600-1000) DEG C, with default heating
After rate and default rate of temperature fall carry out the heat treatment of a period of time, the material that surface is coated with lanthanum sesquioxide can be obtained.
Preferably, the temperature of heat treatment be (700-900) DEG C, further preferably 800 DEG C；The time of heat treatment is (3-
6) h, preferably 5h.It is (1-3) DEG C/min, preferably 2 DEG C/min that default heating rate, which presets rate of temperature fall,；Default rate of temperature fall
For (1-3) DEG C/min, preferably 2 DEG C/min.
When it is implemented, the material that surface can be coated with to lanthanum hydroxide is placed in ceramic crucible, then crucible is put
It is placed in tube furnace, is warming up to (600-1000) DEG C with default heating rate, then room temperature is cooled to default rate of temperature fall
It obtains to surface and is coated with La2O3Material.
The method for coating lanthanum sesquioxide on the surface of the material that first aspect present invention provides, by lithium ion cell positive material
After material, nano-carbon material or aromatic amine high molecular compound wait covering material to mix with lanthanum salt, under the action of complexing agent
The La of formation3+Complex precipitate is dispersed in the surface of material to be covered, after Overheating Treatment, so that being coated on material to be covered
That expect surface is the La of stable structure2O3, the preparation method is at low cost and can guarantee La2O3Uniformly it is deposited in material to be covered
Material surface is especially deposited in pure phase ternary lithium ion cell positive material so as to improve the chemical property of material to be covered
Expect LiNi1/3Co1/3Mn1/3O2Surface when, can be in pure phase ternary lithium ion since the particle of the lanthanum sesquioxide of preparation is smaller
Thin and compact clad is formed outside anode material, so as to reduce active material LiNi1/3Co1/3Mn1/3O2With electrolyte
Between contact probability, simultaneously, it is suppressed that side reaction between the two can effectively inhibit electrolyte to active material LiNi1/ 3Co1/3Mn1/3O2Corrosiveness, and then improve the structural stability of positive electrode.It can also alleviate in charge and discharge process just
The volume change of pole material, is more conducive to the deintercalation of lithium ion, thus the phenomenon that alleviating active material capacity attenuation, so that
Modified ternary cathode material of lithium ion battery has preferable stability and cycle performance.
Second aspect of the present invention provides a kind of anode modified material, which includes pure phase ternary lithium ion
Cell positive material LiNi1/3Co1/3Mn1/3O2With the lanthanum sesquioxide clad for being coated on its surface, wherein lanthanum sesquioxide
Clad is coated on anode material for lithium-ion batteries surface using above-mentioned preparation method, due to the preparation process letter of lanthanum salt complex compound
Single, raw material is easy to get, and complex reaction can be carried out adequately；Simultaneously as La2O3Active force between molecule is larger, it is difficult to
Mix positive electrode LiNi1/3Co1/3Mn1/3O2Internal structure in, therefore will not be to the production of the crystal structure of positive electrode itself
It is raw to influence.Pure phase LiNi in the embodiment of the present invention1/3Co1/3Mn1/3O2For commercial product, without limitation to its source.
Further, in above-mentioned anode modified material, the La2O3Material and the pure phase ternary in clad
Anode material for lithium-ion batteries LiNi1/3Co1/3Mn1/3O2Mass ratio be (0.01-0.05): 1；Preferably (0.02-0.04):
1；Further preferably 0.03:1.The coating layer material and pure phase ternary anode material for lithium-ion batteries LiNi of appropriate mass ratio1/ 3Co1/3Mn1/3O2, the clad type positive electrode of stable structure can be formed, and make the positive electrode have preferable stability and compared with
Good chemical property, in addition, also the capacity of positive electrode can be adjusted by adjusting the mass ratio.
Correspondingly, the molecular formula of the anode modified material can indicate are as follows: x La in the present embodiment2O3/
LiNi1/3Co1/3Mn1/3O2, x=0.01,0.02,0.03,0.04 or 0.05.
Second aspect of the present invention provide anode modified material, by the precipitation method pure phase ternary lithium ion battery just
Pole material LiNi1/3Co1/3Mn1/3O2Surface depositing homogeneous and structural integrity lanthanum sesquioxide clad, activity can be reduced
Substance LiNi1/3Co1/3Mn1/3O2Contact probability between electrolyte can effectively inhibit electrolyte to active material LiNi1/ 3Co1/3Mn1/3O2Corrosiveness, simultaneously, it is suppressed that side reaction between the two；Also, the structure for improving positive electrode is steady
It is qualitative, the volume change of positive electrode in charge and discharge process can also be alleviated, be more conducive to the deintercalation of lithium ion, to alleviate
The phenomenon that active material capacity attenuation so that modified ternary cathode material of lithium ion battery have preferable stability and
Cycle performance.
Detailed description of the invention
By reading the following detailed description of the preferred embodiment, various other advantages and benefits are common for this field
Technical staff will become clear.The drawings are only for the purpose of illustrating a preferred embodiment, and is not considered as to the present invention
Limitation.And throughout the drawings, the same reference numbers will be used to refer to the same parts.In the accompanying drawings:
Fig. 1 is the method flow diagram of the lanthanum sesquioxide of cladding on the surface of the material provided in the embodiment of the present invention；
Fig. 2 a-d is to coat in pure phase ternary cathode material of lithium ion battery and embodiment 1,3,5 in comparative example of the present invention
La2O3Ternary cathode material of lithium ion battery SEM figure；
Fig. 3 a-b is to coat La in pure phase ternary cathode material of lithium ion battery and embodiment 1 in comparative example of the present invention2O3
Ternary cathode material of lithium ion battery TEM figure；
Fig. 4 is to coat La in pure phase ternary cathode material of lithium ion battery and embodiment 1,3,5 in comparative example of the present invention2O3
Ternary cathode material of lithium ion battery XRD diagram；
Fig. 5 is pure phase ternary anode material for lithium-ion batteries LiNi in comparative example of the present invention1/3Co1/3Mn1/3O2And embodiment
1, lithium ion battery ternary modified material after coating lanthanum sesquioxide in 3,5 is 2.5V-4.5V, current density in voltage range
For the constant current charge-discharge curve graph under conditions of 200mA/g；
Fig. 6 is pure phase ternary anode material for lithium-ion batteries LiNi in comparative example of the present invention1/3Co1/3Mn1/3O2In 1C multiplying power
Lower 100 circle of circulation, the charging and discharging curve figure of the 10th circle to 100 circles；
Fig. 7 is the lithium ion battery ternary modified material after cladding lanthanum sesquioxide in the embodiment of the present invention 3 in 1C multiplying power
Lower 100 circle of circulation, the charging and discharging curve figure of the 10th circle to 100 circles；
Fig. 8 is pure phase ternary anode material for lithium-ion batteries LiNi in comparative example of the present invention1/3Co1/3Mn1/3O2And embodiment
1, lithium ion battery ternary modified material after coating lanthanum sesquioxide in 3,5 is 2.5V-4.5V, current density in voltage range
Cycle performance curve graph when for 200mA/g, under different multiplying；
Fig. 9 is pure phase ternary anode material for lithium-ion batteries LiNi in comparative example of the present invention1/3Co1/3Mn1/3O2And embodiment
The CV figure after 100 circle of lithium ion battery ternary modified material circulation after coating lanthanum sesquioxide in 3；
Figure 10 is pure phase ternary anode material for lithium-ion batteries LiNi in comparative example of the present invention1/3Co1/3Mn1/3O2And implement
The EIS figure after 100 circle of lithium ion battery ternary modified material circulation after coating lanthanum sesquioxide in example 3.
Specific embodiment
The following is a preferred embodiment of the present invention, it is noted that for those skilled in the art
For, without departing from the principle of the present invention, some improvements and modifications can also be made, these improvement and modification are also considered as
Protection scope of the present invention.
Embodiment 1 (1) weighs suitable pure phase ternary anode material for lithium-ion batteries LiNi1/3Co1/3Mn1/3O2,
It is added
It into ethyl alcohol, is uniformly dispersed, then 1.0823g lanthanum nitrate is added thereto and obtains A so that lanthanum nitrate is completely dissolved
Mixed liquor；
(2) 1.1523g urea is weighed, is added into 50ml ethyl alcohol, ultrasonic one end time makes it dissolve to obtain B solution, by B
Solution is added dropwise in the A mixed liquor, is stirred when being added dropwise, and keeping bath temperature is 80 DEG C；It is whole to the B solution
Addition starts timing into the A mixed liquor, is vigorously stirred the mixed liquor of the A mixed liquor and the B solution, isothermal reaction
12h obtains C mixed liquor；
(3) precipitating is obtained by filtration in the C mixed liquor, washing collects precipitating, and precipitating is dried at room temperature for, obtains
The LiNi of lanthanum hydroxide cladding1/3Co1/3Mn1/3O2；
(4) LiNi for coating the lanthanum hydroxide1/3Co1/3Mn1/3O2At 800 DEG C, with the heating rate of 2 DEG C/min
After the heat treatment for carrying out 5h with the rate of temperature fall of 2 DEG C/min, lithium ion battery tertiary cathode modified material can be obtained
0.01La2O3LiNi1/3Co1/3Mn1/3O2。
Embodiment 2 (1) weighs suitable pure phase ternary anode material for lithium-ion batteries LiNi1/3Co1/3Mn1/3O2,
It is added in ethyl alcohol, is uniformly dispersed, then 1.08g lanthanum acetate is added thereto, so that lanthanum acetate is complete
Dissolution, obtains A mixed liquor；
(2) 1.54g urea is weighed, is added into 50ml ethyl alcohol, ultrasonic one end time makes it dissolve to obtain B solution, by B
Solution is added dropwise in the A mixed liquor, is stirred when being added dropwise, and keeping bath temperature is 80 DEG C；It is whole to the B solution
Addition starts timing into the A mixed liquor, is vigorously stirred the mixed liquor of the A mixed liquor and the B solution, isothermal reaction
12h obtains C mixed liquor；
(3) precipitating is obtained by filtration in the C mixed liquor, washing collects precipitating, and precipitating is dried at room temperature for, obtains
The LiNi of lanthanum hydroxide cladding1/3Co1/3Mn1/3O2；
(4) LiNi for coating the lanthanum hydroxide1/3Co1/3Mn1/3O2At 800 DEG C, with the heating rate of 3 DEG C/min
After the heat treatment for carrying out 5h with the rate of temperature fall of 1 DEG C/min, lithium ion battery tertiary cathode modified material can be obtained
0.02La2O3LiNi1/3Co1/3Mn1/3O2。
Embodiment 3 (1) weighs suitable pure phase ternary anode material for lithium-ion batteries LiNi1/3Co1/3Mn1/3O2,
It is added in ethyl alcohol, is uniformly dispersed, then 1.0823g lanthanum chloride is added thereto, so that lanthanum chloride is complete
Fully dissolved obtains A mixed liquor；
(2) 1.92g urea is weighed, is added into 50ml ethyl alcohol, ultrasonic one end time makes it dissolve to obtain B solution, by B
Solution is added dropwise in the A mixed liquor, is stirred when being added dropwise, and keeping bath temperature is 80 DEG C；It is whole to the B solution
Addition starts timing into the A mixed liquor, is vigorously stirred the mixed liquor of the A mixed liquor and the B solution, isothermal reaction
12h obtains C mixed liquor；
(3) precipitating is obtained by filtration in the C mixed liquor, washing collects precipitating, and precipitating is dried at room temperature for, obtains
The LiNi of lanthanum hydroxide cladding1/3Co1/3Mn1/3O2；
(4) LiNi for coating the lanthanum hydroxide1/3Co1/3Mn1/3O2At 700 DEG C, with the heating rate of 1 DEG C/min
After the heat treatment for carrying out 5h with the rate of temperature fall of 2 DEG C/min, lithium ion battery tertiary cathode modified material can be obtained
0.03La2O3LiNi1/3Co1/3Mn1/3O2。
Embodiment 4 (1) weighs suitable pure phase ternary anode material for lithium-ion batteries LiNi1/3Co1/3Mn1/3O2,
It is added in ethyl alcohol, is uniformly dispersed, then 1.0823g lanthanum nitrate is added thereto, so that lanthanum nitrate is complete
Fully dissolved obtains A mixed liquor；
(2) 2.3g urea is weighed, is added into 50ml ethyl alcohol, ultrasonic one end time makes it dissolve to obtain B solution, and B is molten
Liquid is added dropwise in the A mixed liquor, is stirred when being added dropwise, and keeping bath temperature is 80 DEG C；All add to the B solution
Enter and start timing into the A mixed liquor, is vigorously stirred the mixed liquor of the A mixed liquor and the B solution, isothermal reaction 12h,
Obtain C mixed liquor；
(3) precipitating is obtained by filtration in the C mixed liquor, washing collects precipitating, and precipitating is dried at room temperature for, obtains
The LiNi of lanthanum hydroxide cladding1/3Co1/3Mn1/3O2；
(4) LiNi for coating the lanthanum hydroxide1/3Co1/3Mn1/3O2At 900 DEG C, with the heating rate of 2 DEG C/min
After the heat treatment for carrying out 3h with the rate of temperature fall of 2 DEG C/min, lithium ion battery tertiary cathode modified material can be obtained
0.04La2O3LiNi1/3Co1/3Mn1/3O2。
Embodiment 5 (1) weighs suitable pure phase ternary anode material for lithium-ion batteries LiNi1/3Co1/3Mn1/3O2,
It is added in ethyl alcohol, is uniformly dispersed, then 1.0823g lanthanum nitrate is added thereto, so that lanthanum nitrate is complete
Fully dissolved obtains A mixed liquor；
(2) 2.688g urea is weighed, is added into 50ml ethyl alcohol, ultrasonic one end time makes it dissolve to obtain B solution, by B
Solution is added dropwise in the A mixed liquor, is stirred when being added dropwise, and keeping bath temperature is 80 DEG C；It is whole to the B solution
Addition starts timing into the A mixed liquor, is vigorously stirred the mixed liquor of the A mixed liquor and the B solution, isothermal reaction
12h obtains C mixed liquor；
(3) precipitating is obtained by filtration in the C mixed liquor, washing collects precipitating, and precipitating is dried at room temperature for, obtains
The LiNi of lanthanum hydroxide cladding1/3Co1/3Mn1/3O2；
(4) LiNi for coating the lanthanum hydroxide1/3Co1/3Mn1/3O2At 1000 DEG C, with the heating speed of 2 DEG C/min
After the rate of temperature fall of rate and 2 DEG C/min carry out the heat treatment of 6h, lithium ion battery tertiary cathode modified material can be obtained
0.05La2O3LiNi1/3Co1/3Mn1/3O2。
Comparative example
To the pure phase ternary anode material for lithium-ion batteries LiNi of purchase1/3Co1/3Mn1/3O2It is without any processing.
Experimental example
In order to verify La2O3Whether positive electrode LiNi is successfully coated on1/3Co1/3Mn1/3O2Surface and La2O3Cladding
Influence of the layer to tertiary cathode material crystal structure, has carried out SEM, TEM to the positive electrode in embodiment and comparative example respectively
And XRD test.As a result as in Figure 2-4:
Fig. 2 a is LiNi in comparative example1/3Co1/3Mn1/3O2Scanning electron microscope (SEM) photograph, Fig. 2 b-d be respectively embodiment 1,3,5 make
The x La of the different coating contents obtained2O3/LiNi1/3Co1/3Mn1/3O2Scanning electron microscope (SEM) photograph, it can be seen that it is uncoated in comparative example
LiNi1/3Co1/3Mn1/3O2Material be stacked with by rod-shpaed particle composed by, the surface of particle is smooth, particle it
Between not dense packing, mutually there is gap.La after caning be found that cladding in Fig. 2 b-d2O3/LiNi1/3Co1/3Mn1/3O2Table
Face becomes coarse rough, and with the presence of tiny white particle, this result illustrates the lanthanum sesquioxide packet of sample surfaces
Coating is the aggregation being made of a large amount of nano particle.Work as La2O3When covering amount is 1wt%, although there are one on the surface of sample
A little tiny particles but still smoother, but the sufficiently complete densification of clad.Work as La2O3When covering amount is 3wt%, material
The degree of roughness on surface is reinforced, but gap is still had between the particle of ternary material, and can be seen that particle surface is formed
Fine and close clad, this structure not only improve the infiltration of electrolyte, and can be to send out between inhibitory activity substance and electrolyte
Raw side reaction, prevents corrosion of the electrolyte for active material, therefore is conducive to improve the chemical property of material.Work as La2O3Packet
When the amount of covering is 5wt%, material surface forms thicker clad, blocks the hole between ternary material particle, is unfavorable for
The infiltration of electrolyte can cause to hinder to the diffusion of lithium ion.
In order to further appreciate that the variation of cladding front and back material surface, by LiNi uncoated in comparative example1/3Co1/ 3Mn1/3O2X La made from material and embodiment 12O3/LiNi1/3Co1/3Mn1/3O2The characterization of transmission electron microscope is carried out respectively
Figure, as a result respectively as shown in Fig. 3 a, 3b.It can be seen that uncoated LiNi from Fig. 3 a1/3Co1/3Mn1/3O2Surface is smooth.From figure
3b can be seen that cladding La2O3Positive electrode surface become coarse rough, the characterization result and above-mentioned scanning electron microscopy
Mirror characterizes obtained result and is consistent, and illustrates La2O3Successfully it is coated on LiNi1/3Co1/3Mn1/3O2Material surface.
Fig. 4 is positive electrode and x La made from embodiment 1,3,5 in comparative example2O3/LiNi1/3Co1/3Mn1/3O2XRD
Phenogram.It can be seen from the figure that the material of cladding front and back all has α-NaFeO2Layered rock salt structure, belong to six sides
Crystallographic system, R-3m space group.The diffraction maximum of each sample is sharp in figure, occurs without impurity peaks, it was demonstrated that the crystallinity of each sample is good
It is good.For ternary material, (006) and (102) and (108) and (110) two groups of peaks split point degree and can be used to characterize material
Whether there is good layer structure.It is generally believed that (006) and (102) and (108) and (110) two groups of peaks split a point degree
It is bigger, it splits and point is more obvious, it was demonstrated that the layer structure feature of ternary material is more obvious, not vice versa.It can be found that packet from figure
(006) and (102) and (108) and (110) two groups of peak homolysis for covering the sample of front and back are shown clearly, it was demonstrated that sample all has very
Good layer structure.For stratified material, mixing can also be characterized according to the ratio of the relative intensity of certain characteristic peaks
The degree of crystallization of degree and material.It is generally believed that the intensity ratio of characteristic peak I003 and I104 can be used for measuring material Li+
And Ni2+The ratio of mixing degree, I003 and I104 are bigger, it was demonstrated that the Li of the material+And Ni2+The degree of mixing is smaller, crystallization
Degree is higher.Li+And Ni2+The spacing that mixing will lead to lithium layer becomes smaller, and the diffusion admittance of lithium ion becomes smaller, thus to lithium ion
Diffusion causes to hinder, therefore should reduce mixing degree as far as possible by calculating it is found that coating preceding LiNi1/3Co1/3Mn1/3O2's
I003/I104 peak value ratio is 1.138, and lanthanum sesquioxide coating content is 1wt%, the peak sample I003/I104 of 3wt%, 5wt%
Value is than being respectively 1.408,1.521,1.414.La is coated by surface2O3, Li can be reduced+And Ni2+The degree of mixing, wherein
The ratio that embodiment 3, i.e. coating content are the sample I003 and I104 of 3wt% is maximum, it was demonstrated that its Li+And Ni2+The degree of mixing
Small, degree of crystallization is high, can preferably maintain the layer structure of crystal, also be more conducive to the diffusion of lithium ion.
Meanwhile in order to detect every chemical property of the cell positive material in embodiment and comparative example, to above-mentioned tool
Body example carries out electrochemical property test respectively, and figure 5-8 shows experimental result.
As can be seen from Figure 5 uncoated LiNi1/3Co1/3Mn1/3O2First discharge specific capacity be 181.6 mAh/g,
La2O3Coating content is 1wt%, and the sample first discharge specific capacity of 3wt%, 5wt% are respectively 181mAh/g, 181.3mAh/g
And 179.9mAh/g.By 100 circle circulation after, the specific discharge capacity of above-mentioned sample be respectively 70.2mAh/g, 174.3mAh/g,
158.5mAh/g and 156.7mAh/g.Its capacity retention ratio is respectively 38.6%, 87.56%, 96.13%, 87.1%.It can see
Out, La2O3Material capacity conservation rate after cladding obviously rises, from the above in be very easy to find, the content of lanthanum sesquioxide
The most excellent for the cycles samples stability of 3wt%, this is primarily due to the Ni that ternary material generates under high pressure4+It is easy
It reacts with electrolyte, the quality of active material is caused to decline, however, passing through cladding La2O3It can be in the table of ternary material
Face forms protective layer, electrolyte can be reduced to the corrosiveness of active material, to improve its cyclical stability.
Fig. 6-Fig. 7 shows LiNi uncoated in comparative example1/3Co1/3Mn1/3O2And La2O3Covering amount is the sample of 3 wt%
Product recycle 100 circles, the 10th, 20 charging and discharging curve figures enclosed until 100 under 1C multiplying power.It can see from Fig. 6 and Fig. 7, two
The charging and discharging curve of kind sample is all very smooth, and only exists a pair of of charge and discharge platform, and corresponding is Ni2+Redox it is anti-
It answers.By 100 circle circulations, uncoated sample voltage platform decline is fairly obvious, and by coating three on positive electrode surface
Aoxidize two lanthanums, it will be apparent that inhibit the decline of voltage platform, the cyclical stability of cell positive material has obtained greatly mentioning
It is high.
Fig. 8 is shown to uncoated LiNi1/3Co1/3Mn1/3O2And the La of different covering amounts2O3/ LiNi1/3Co1/ 3Mn1/3O2Sample is 2.5V-4.5V in voltage range, carries out charge and discharge cycles test.Respectively according to 0.2C, 0.5C, 1.0C,
The charge-discharge magnification of 2.0C, 3.0C, 5.0C (1C=200mA/g) carry out charge and discharge cycles, respectively recycle 5 under 0.2C and 0.5C multiplying power
It is secondary, 10 result figures are recycled under other each multiplying powers.
From figure 8, it is seen that sample the putting under 0.2C, 0.5C, 1.0C, 2.0C, 3.0C, 5.0 C multiplying powers before cladding
Electric specific capacity is respectively 189mAh/g, 172.7mAh/g, 158.4mAh/g, 140.3 mAh/g, 115.8mAh/g, 86.9mAh/
G coats La2O3Content be 1wt% sample specific discharge capacity be respectively 183mAh/g, 169.1mAh/g, 160.5mAh/
G, 143.7mAh/g, 130.8 mAh/g, 113.4mAh/g coat La2O3The sample that content is 3wt% specific discharge capacity point
Not Wei 187mAh/g, 182mAh/g, 171.2mAh/g, 157.2mAh/g, 146.8mAh/g, 137.5mAh/g, coat La2O3Contain
Amount be 5wt% sample specific discharge capacity be respectively 179.7mAh/g, 174.8 mAh/g, 162.6mAh/g,
149.2mAh/g,141.4mAh/g,129.4mAh/g.It can be seen that under each current density, the multiplying power of the sample after cladding
Performance all has biggish raising, and under high current density, increase it is more obvious.Wherein La2O3Covering amount is 3wt%
Properties of sample improve it is the most excellent.Why this phenomenon can occur, and be primarily due to battery and carry out charge and discharge under big multiplying power
Lithium ion is needed to carry out quick deintercalation in the material when electric, but with electrode material pair can occur for electrolyte in cyclic process
Reaction, causes impedance to increase, so that the diffusion rate of lithium ion declines.However lanthanum sesquioxide can consume electrolyte decomposition
When the part hydrofluoric acid that generates, and lanthanum sesquioxide clad is thin and compact clad, can with inhibitory activity substance with
Side reaction between electrolyte, to improve the high rate performance of the material.
In order to be best understood from electrode material in the microreaction of charge and discharge process and the invertibity of electrode material, Yi Jisan
Two lanthanums cladding is aoxidized on influence caused by electrode reaction impedance, cyclic voltammetry and friendship have been carried out respectively to electrode material
Flow impedance test.Fig. 9-Figure 10 is respectively LiNi uncoated in comparative example1/3Co1/3Mn1/3O2And La2O3Covering amount is 3wt%
Sample 100 circles are recycled under 1C multiplying power after carry out cyclic voltammetry and the obtained result of ac impedance measurement.Circulation
The voltage range of volt-ampere test is 2.5V-4.5.V, scanning speed 0.1mV/s.
As it can be seen in figure 9 that only there is a pair of of redox peaks, and redox electricity in the material of cladding front and back
Position is between 3.6V-4.1V, as the characteristics of ternary material it is found that being Ni corresponding to the redox peaks2+Oxidation also
Original reaction；It is that 4.6V or so redox peaks does not occur in voltage range, it was demonstrated that Co3+Redox reaction does not occur.And
And it can be seen that cladding 3wt%La2O3Sample anode peak and cathode peak between there is smaller potential difference, and peak shape is more
Add it is sharp and symmetrical, these results suggest that by cladding after, polarization of electrode is smaller, have better invertibity.
Figure 10 is the EIS figure that ac impedance measurement obtains, and as can be seen from the figure the AC impedance spectroscopy of two samples is all
Include two parts: the semicircle of high frequency region and the straight line of low frequency range.What wherein the semicircle of high frequency region represented is electrode and solution interface
Load transfer impedance Rct；And corresponding to the straight line of low frequency range be Warburg impedance, the wire body it is existing be lithium ion in ternary material
Expect the diffusion process in ontology.Uncoated material is enclosing the load transfer impedance after recycling by 100 close to 200 Ω, and coats
3wt%La2O3Sample obtain load transfer impedance and there was only 140 Ω or so, by the cladding of lanthanum sesquioxide, effectively reduce load transfer
Impedance.It is primarily due to the cladding by lanthanum sesquioxide, the stability of material structure can be improved, be more conducive to lithium ion
Deintercalation；The direct contact probability between active material and electrolyte can be reduced simultaneously, it is suppressed that side reaction between the two.
The embodiments described above only express several embodiments of the present invention, and the description thereof is more specific and detailed, but simultaneously
Limitations on the scope of the patent of the present invention therefore cannot be interpreted as.It should be pointed out that for those of ordinary skill in the art
For, without departing from the inventive concept of the premise, various modifications and improvements can be made, these belong to guarantor of the invention
Protect range.Therefore, the scope of protection of the patent of the invention shall be subject to the appended claims.
Claims (10)
1. a kind of method for coating lanthanum sesquioxide on the surface of the material, which comprises the following steps:
(1) material to be covered and lanthanum salt are successively distributed in solvent, obtain the first mixed liquor；
(2) appropriate complexing agent is taken, dissolution obtains enveloping agent solution；
(3) enveloping agent solution is added dropwise in first mixed liquor, after heated stirring, precipitating is obtained by filtration, clean,
It collects the precipitating and it is dried and is heat-treated, the material that surface is coated with lanthanum sesquioxide can be obtained.
2. the method according to claim 1 for coating lanthanum sesquioxide on the surface of the material, which is characterized in that described to be covered
Material is anode material for lithium-ion batteries, nano-carbon material or aromatic amine high molecular compound.
3. the method according to claim 1 for coating lanthanum sesquioxide on the surface of the material, which is characterized in that the lanthanum salt is
At least one of lanthanum nitrate, lanthanum acetate and lanthanum chloride.
4. the method according to claim 1 for coating lanthanum sesquioxide on the surface of the material, which is characterized in that the complexing agent
For urea, ethylenediamine tetra-acetic acid, hydroxyl ethylenediamine tetra-acetic acid or diethylene triamine pentacetic acid (DTPA).
5. it is according to claim 1 on the surface of the material coat lanthanum sesquioxide method, which is characterized in that the lanthanum salt with
The mass ratio of the complexing agent is 1.08:(1.15~2.69).
6. the method according to claim 1 for coating lanthanum sesquioxide on the surface of the material, which is characterized in that the step
(3) in, the temperature of heating water bath is (60-90) DEG C.
7. the method according to claim 1 for coating lanthanum sesquioxide on the surface of the material, which is characterized in that the step
(3) it in, is all added to the enveloping agent solution and starts timing into first mixed liquor, isothermal reaction (10-16) h will
Precipitating is obtained by filtration in the second obtained mixed liquor, and washing collects precipitating, and precipitating is dried at room temperature for, and obtains surface cladding
There is the material of lanthanum hydroxide.
8. the method according to claim 7 for coating lanthanum sesquioxide on the surface of the material, which is characterized in that the step
(3) in, the surface is coated with the material of lanthanum hydroxide at (600-1000) DEG C, with default heating rate and default cooling
After rate carries out the heat treatment of a period of time, the material that surface is coated with lanthanum sesquioxide can be obtained.
9. a kind of anode modified material of the preparation of the method as described in any one of the claims 1 to 8, feature exist
In, including pure phase ternary anode material for lithium-ion batteries LiNi1/3Co1/3Mn1/3O2With the lanthanum sesquioxide packet for being coated on its surface
Coating.
10. anode modified material according to claim 9, which is characterized in that three oxidations two in the clad
Lanthanum and the pure phase ternary anode material for lithium-ion batteries LiNi1/3Co1/3Mn1/3O2Mass ratio be (0.01-0.05): 1；Institute
The molecular formula for stating lithium ion battery tertiary cathode modified material is xLa2O3LiNi1/3Co1/3Mn1/3O2, wherein x=0.01,
0.02,0.03,0.04 or 0.05.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103811765A (en) * | 2014-02-27 | 2014-05-21 | 广西师范大学 | Two-dimensional nanocrystalline metal oxide composite coating lithium manganate positive electrode material and preparation method thereof |
| CN105680015A (en) * | 2016-01-28 | 2016-06-15 | 深圳大学 | Cathode material formed by coating lanthanum oxide on surface of ternary material and preparation method of cathode material |
| CN105778154A (en) * | 2014-12-20 | 2016-07-20 | 天津滨浦生产力促进有限公司 | Preparation method of lanthana coated inorganic nano-powder |
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2018
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Patent Citations (3)
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|---|---|---|---|---|
| CN103811765A (en) * | 2014-02-27 | 2014-05-21 | 广西师范大学 | Two-dimensional nanocrystalline metal oxide composite coating lithium manganate positive electrode material and preparation method thereof |
| CN105778154A (en) * | 2014-12-20 | 2016-07-20 | 天津滨浦生产力促进有限公司 | Preparation method of lanthana coated inorganic nano-powder |
| CN105680015A (en) * | 2016-01-28 | 2016-06-15 | 深圳大学 | Cathode material formed by coating lanthanum oxide on surface of ternary material and preparation method of cathode material |
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| Title |
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| 贾晨晓: ""锂离子电池LiNi1/3Co1/3Mn1/3O2三元正极材料制备及其改性研究"", 《中国优秀硕士学位论文全文数据库-工程科技Ⅱ辑》 * |
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