A kind of preparation method of carbon coating tertiary cathode material
Technical field
The present invention relates to technical field of lithium ion, and in particular to a kind of preparation side of carbon coating tertiary cathode material
Method.
Background technique
Current commercialized anode material for lithium-ion batteries is probably divided into three classes according to its structure: the first kind is that have
The lithium metal oxide LiMO of six side's layer structures2(M=Co, Ni, Mn), represent material be mainly cobalt acid lithium, ternary just
Pole material (NCM, NCA), rich lithium material.Second class is the material of spinel structure, represents material mainly and have 4V grades of mangaic acid
Lithium (LiMn2O4).Third class is the compound with polyanionic structure, and representing material is mainly the phosphorus for having olivine structural
Sour iron lithium (LiFePO4)。
Wherein tertiary cathode material energy density with higher, it is environmental-friendly the features such as, this makes ternary material gradually
First choice as power battery anode material.But the material also has its defect, such as cycle performance decline, high rate performance is poor,
This is also the reason of limitation ternary material rapidly develops.
For above problem, the surface of ternary material is modified to can solve certain problem, the modified packet in general surface
Include doping and surface cladding.Wherein cladding means can reduce side reaction of material during circulating battery, carry out to material
Protection, and the covering material of some functionalization can further promote the cycle performance and high rate performance of material.
Carbon coating is to improve the important means of material conductivity, and low cost, advantages of environment protection make carbon coating gradually
The Critical policies modified as positive electrode.Such as the various carbon coating means of LiFePO4, it has obtained on the market at present
It is widely applied.
Mostly using organic matter sugarcane sugar and starch as carbon source in document, heating carbonization in an inert atmosphere.Carbon coating is as anode
The protective layer of material reduces charge transfer impedance, can inhibit the dissolution of metal ion, in addition, carbon coating can also be improved material
The surface electronic conductivity of material improves the electrical contact between material granule, and then improves the chemical property of material.
The patent document of Publication No. CN103474628A discloses a kind of preparation method of carbon coating tertiary cathode material,
The following steps are included: S1, using nickel salt, cobalt salt and manganese salt as raw material, prepare ternary anode material precursor;S2, preparation conductive carbon
Dispersion: it disperses conductive carbon in the water containing organic carbon source;S3, ternary anode material precursor and lithium compound are added
Enter into conductive carbon dispersion, be uniformly mixed, obtains mixture;S4, mixture is dried under vacuum conditions;S5, will be through
The mixture of drying is in confined conditions or the atmosphere high temperature of inert gas shielding is handled, and obtains carbon coating tertiary cathode material
Material.
But for oxide-based tertiary cathode material, promotion and improvement of the carbon coating of commonsense method for performance
It is also extremely limited.Reason is common carbon coating means during carbonization, and carbon source will form the CO with reproducibility
Or the reducibility gas such as H2, it has a certain impact to tertiary cathode material, the valence state of various metals generates variation, so that brilliant
The decline of lattice structure.
Summary of the invention
The purpose of the present invention is to provide a kind of preparation methods of carbon coating tertiary cathode material, to overcome existing carbon packet
The problem of tertiary cathode material is easily restored by carbon under the high temperature conditions in coating method.
To achieve the above object, the present invention adopts the following technical scheme:
A kind of preparation method of carbon coating tertiary cathode material, comprising the following steps:
(1) tertiary cathode material and silica precursor are added in organic solvent, are uniformly mixed, then deionization is added dropwise
Water is stirred to react, and is then evaporated all solvents, and calcining obtains the tertiary cathode material of coated with silica;
(2) tertiary cathode material of coated with silica and organic carbon source are added in dispersing agent, obtain suspension, is evaporated
It is sintered the tertiary cathode material that silica and carbon dual cladding is made afterwards;
(3) tertiary cathode material of silica and carbon dual cladding is soaked in alkaline solution, obtains carbon coating three
First positive electrode.
In preparation method of the invention, step (1) formed coated with silica layer step (2) high temperature cabonization process
In serve as protective layer, to inhibit carbon at high temperature to the reduction of tertiary cathode material, also just solve at present tradition it is carbon-coated
One drawback.After the carbon coating layer that step (2) are formed, silica loses original effect, by step (3) in alkali
Property solution in etching to form single clad.
The tertiary cathode material can be nickel-cobalt-manganternary ternary anode material (NCM), nickel cobalt aluminium tertiary cathode material
(NCA)。
Preferably, the tertiary cathode material is nickel-cobalt-manganternary ternary anode material, chemical molecular formula in step (1)
For Li (Ni1-x-yCoxMny)O2, wherein 0 < x < 0.4,0 < y < 1.The molar ratio of nickel cobalt manganese is 6:2:2,5:2:3,4:4:2 or 1:1:
1。
Preferably, the silica precursor is silica dioxide granule, silicon tetrachloride, positive silicic acid in step (1)
One of ethyl ester, dimethylsilane are a variety of.
Preferably, the silica precursor is with the mass ratio of tertiary cathode material in terms of silica
0.005-0.2:1。
More preferably, ethyl orthosilicate is 0.01:1 with the mass ratio of tertiary cathode material in terms of silica.
Preferably, in step (1), the organic solvent be one of methanol, ethyl alcohol, isopropanol, ethylene glycol or
It is a variety of.
Preferably, the temperature being stirred to react is 20-80 DEG C, revolving speed 800-1000r/min in step (1), when
Between be 2-7h.Deionized water is added dropwise according to stoichiometric ratio, while stirring Si (OH) x for guaranteeing tetraethyl orthosilicate and hydrolyzing
It uniformly adequately covers on the surface of the material.
More preferably, the temperature being stirred to react is 60 DEG C, revolving speed 800r/min, time 3h.
The calcining carries out in air atmosphere, preferably, the temperature of the calcining is 200-700 in step (1)
DEG C, time 2-8h.
More preferably, the temperature of the calcining is 500 DEG C, time 5h.
In step (2), the organic carbon source can be high-molecular organic material or glucide, preferably, described
Organic carbon source be one of sucrose, glucose, polyacrylic acid, starch, polyethylene glycol, dopamine or a variety of.
Preferably, the tertiary cathode material of coated with silica and the mass ratio of organic carbon source are 1 in step (2):
0.01-0.1。
More preferably, the tertiary cathode material of coated with silica and the mass ratio of glucose are 0.05:1.
Preferably, the dispersing agent is water, ethyl alcohol, ethylene glycol, methylene chloride, methanol, isopropanol in step (2)
One of or it is a variety of.
The sintering carries out in protective atmosphere, and the protective atmosphere can be nitrogen.Preferably, in step (2), institute
The temperature for the sintering stated is 100-1000 DEG C, time 1-20h.
More preferably, the temperature of the sintering is 800 DEG C, time 3h.
In step (3), alkaline solution falls the silica coated in ternary material and remaining pasc reaction.As excellent
Choosing, in step (3), the alkaline solution be one of sodium hydroxide, potassium hydroxide, ammonium hydroxide, sodium bicarbonate, sodium carbonate or
It is a variety of.
Preferably, the concentration of the alkaline solution is 0.1mol/L-2mol/L in step (3).
More preferably, the alkaline solution concentration is 0.5mol/L.
Preferably, the time impregnated is 1-2h.
It is that the present invention has the utility model has the advantages that
In carbon coating tertiary cathode material preparation method provided by the invention, using silicon dioxide layer as intermediate protection
Layer prevents carbon source from discharging reducibility gas reduction material of main part during high temperature cabonization, and the carbon coating of formation, which gives full play to, to be led
The excellent electric conductivity of electrical carbon improves the high current charge-discharge ability of battery, and then improves high rate performance.
Detailed description of the invention
Fig. 1 is the SEM figure of carbon coating nickel-cobalt-manganternary ternary anode material made from embodiment 1.
Fig. 2 is the SEM figure of carbon coating nickel-cobalt-manganternary ternary anode material made from embodiment 2.
Fig. 3 is the SEM figure of carbon coating nickel-cobalt-manganternary ternary anode material made from comparative example 1.
Fig. 4 is the SEM figure of the uncoated nickel-cobalt-manganternary ternary anode material of comparative example 2.
Fig. 5 is the TEM figure of carbon coating nickel-cobalt-manganternary ternary anode material made from embodiment 1.
Fig. 6 is the TEM figure of carbon coating nickel-cobalt-manganternary ternary anode material made from embodiment 2.
Fig. 7 is the TEM figure of carbon coating nickel-cobalt-manganternary ternary anode material made from comparative example 1.
Fig. 8 is the TEM figure of the uncoated nickel-cobalt-manganternary ternary anode material of comparative example 2.
Fig. 9 is the XRD diagram of 2 sample of carbon coating nickel-cobalt-manganternary ternary anode material and comparative example made from embodiment 1-3.
Figure 10 is the forthright again of carbon coating nickel-cobalt-manganternary ternary anode material and comparative example 1-2 sample made from embodiment 2-3
It can figure.
Figure 11 is the cycle performance of 1 sample of carbon coating nickel-cobalt-manganternary ternary anode material and comparative example made from embodiment 1-3
Figure.
Specific embodiment
The present invention will be further described below with reference to examples.Following embodiment is only intended to clearly illustrate this
The performance of invention, and the following examples cannot be limited only to.
Embodiment 1
A kind of novel carbon coating nickel-cobalt-manganternary ternary anode material, preparation method are as follows:
Step 1, the NCM622 prepared, i.e. Li (Ni0.6Co0.2Mn0.2)O2For basis material, naked ternary material and
Ethyl orthosilicate (being converted to silica) 1:0.01 in mass ratio is blended in ethyl alcohol phase, 60 DEG C of stirring 3h, is counted according to chemistry
Amount is warming up to 100 DEG C after 800r/min reaction 3h and distributes all solvents, scrape powder than a certain amount of deionized water is slowly added dropwise
It is placed in 500 DEG C of air and is sintered 5h, then cooled down, therefrom obtain the ternary material of coated with silica, be denoted as
SiO2@NCM。
Step 2 is added to 5% glucose solution using the coated with silica ternary material in experimental procedure one
Middle heating stirring, is evaporated to dryness, and is then placed in tube furnace 800 DEG C and is sintered 3h under the atmosphere of nitrogen, silica and carbon
Ternary material is covered in double-contracting, is denoted as C/SiO2@NCM。
Step 3 is put into immersion 1h in the NaOH solution of 0.5mol/L using the material in experimental procedure two and etches away, obtains
To simple carbon encapsulated material, then filtering drying, completes the preparation of carbon-coated positive electrode, is named as #1.
As shown in Figure 1, the SEM for carbon coating nickel-cobalt-manganternary ternary anode material schemes;As shown in figure 5, being carbon coating nickel cobalt manganese
The TEM of tertiary cathode material schemes.
Embodiment 2
A kind of novel carbon coating nickel-cobalt-manganternary ternary anode material, preparation method are as follows:
Step 1 is basis material the NCM622 prepared, naked ternary material and silicon tetrachloride (is converted to titanium dioxide
Silicon) 1:0.005 in mass ratio is blended in ethyl alcohol phase, and 20 DEG C are stirred, 7h, and a certain amount of deionization is being added dropwise according to stoichiometric ratio
Water is warming up to 100 DEG C and distributes all solvents after 800r/min reaction 3h, scrapes powder and is placed in 200 DEG C of air and is sintered 8h,
Then it is cooled down, therefrom obtains the ternary material of coated with silica, be denoted as SiO2@NCM。
Step 2 coats ternary material using the silica in experimental procedure one, is added in 1% glucose solution
Heating stirring is evaporated to dryness, and is then placed in tube furnace and is sintered 20h, pair of silica and carbon under the atmosphere of nitrogen for 100 DEG C
Ternary material is coated, C/SiO is denoted as2@NCM。
Step 3 is put into immersion 1h in the ammonia spirit of 0.1mol/L using the material in experimental procedure two and etches away, obtains
To simple carbon encapsulated material, then filtering drying, completes the preparation of carbon-coated positive electrode, is named as #2.
As shown in Fig. 2, the SEM for carbon coating nickel-cobalt-manganternary ternary anode material schemes;As shown in fig. 6, being carbon coating nickel cobalt manganese
The TEM of tertiary cathode material schemes.
Embodiment 3
A kind of novel carbon coating nickel-cobalt-manganternary ternary anode material, preparation method are as follows:
Step 1: being basis material the NCM622 prepared, in mass ratio naked ternary material and silica dioxide granule
1:0.02 is blended in methanol phase, 80 DEG C of stirring 2h, and a certain amount of deionized water, 800r/min is being added dropwise according to stoichiometric ratio
It is warming up to 100 DEG C after reaction 3h and distributes all solvents, scrape powder and be placed in 700 DEG C of air and be sintered 2h, then carry out cold
But, the ternary material for therefrom obtaining coated with silica, is denoted as SiO2@NCM。
Step 2: coating ternary material using the silica in experimental procedure one, it is added to 10% glucose solution
Middle heating stirring, is evaporated to dryness, and is then placed in tube furnace 1000 DEG C and is sintered 1h under the atmosphere of nitrogen, silica and carbon
Ternary material is covered in double-contracting, is denoted as C/SiO2@NCM。
It is etched away Step 3: being put into the KOH solution of 2mol/L using the material in experimental procedure two and impregnating 1h, obtains list
Pure carbon encapsulated material, then filtering drying, completes the preparation of carbon-coated positive electrode, is named as #3.
Comparative example 1
A kind of common carbon coating nickel-cobalt-manganternary ternary anode material, preparation method are as follows:
It is basis material the NCM622 prepared, is added to heating stirring in 10% glucose solution, is evaporated to
It is dry.It is then placed in tube furnace and is sintered 3h under the atmosphere of nitrogen for 800 DEG C.Carbon-coated nickel-cobalt-manganternary ternary anode material is obtained,
It is named as #4.
As shown in figure 3, the SEM for common carbon coating nickel-cobalt-manganternary ternary anode material schemes;As shown in fig. 7, being common carbon packet
Cover the TEM figure of nickel-cobalt-manganternary ternary anode material.
Comparative example 2
Using NCM622 as uncoated nickel-cobalt-manganternary ternary anode material, it is named as #.As shown in figure 4, being uncoated nickel cobalt
The SEM of manganese tertiary cathode material schemes;As shown in figure 8, the TEM for uncoated nickel-cobalt-manganternary ternary anode material schemes.
Application examples
1, apparent analysis
As can be seen from Figure 9: there is no variations for the main structure of the nickel-cobalt-manganternary ternary anode material of embodiment 1-3 carbon coated.
2, performance test:
Assembled battery method: by the embodiment 1-3 and comparative example 1-2 positive electrode powder prepared and conductive black super
P and binder Kynoar (PVDF) are uniform according to mass ratio 85:10:5 hand lapping.A certain amount of 1- methyl -2- is added
Pyrrolidones (NMP) is stirred evenly with homogenate flesh.Then it is scratched with plate coating machine, blade coating thickness is set as 0.02mm
(before drying).It is put into 80 DEG C to dry five hours, places into 100 DEG C of vacuum oven overnights.It is cut to the electrode that diameter is 11.7mm
Piece is put into argon air box assembled battery in order later.It is tested after standing one day after being completed.
Test method: battery is tested on blue electricity 5V-5mA or 5V-10mA battery test system, and test method is with electric current
Density is to carry out charge-discharge test in the electrochemical window of 2.8-4.3V subject to 1C=180mA/g;And with 0.2C, 0.5C, 1C,
The circulation of charge and discharge is completed under 2C, 5C different multiplying powers.
It was found from Figure 10 and Figure 11: embodiment 1 prepares the tertiary cathode material of carbon at voltage 4.3V, for the first time discharge capacity
For 179.5mAh/g, capacity is in 173.8mAh/g, capacity retention ratio 96.8% after 50 circulations.Ternary material it is forthright again
Can, the specific discharge capacity under the multiplying power of 0.2C, 0.5C, 1C, 2C, 5C be respectively 181mAh/g, 176mAh/g, 167mAh/g,
150mAh/g,138mAh/g.It recycles its specific capacity under 0.2C again after circulation and is still maintained at 178mAh/g.
Embodiment 2 prepares the tertiary cathode material of carbon at voltage 4.3V, and discharge capacity is 172.2mAh/g for the first time, through 50
Capacity is in 153mAh/g, capacity retention ratio 88.9% after secondary circulation.The high rate performance of ternary material, 0.2C, 0.5C, 1C,
Specific discharge capacity under the multiplying power of 2C, 5C is respectively 179mAh/g, 173mAh/g, 167mAh/g, 158mAh/g, 139mAh/g.
It recycles its specific capacity under 0.2C again after circulation and is still maintained at 172mAh/g.
Embodiment 3 prepares the tertiary cathode material of carbon at voltage 4.3V, and discharge capacity is 163mAh/g for the first time, through 50 times
Capacity is in 154mAh/g, capacity retention ratio 94.5% after circulation.The high rate performance of ternary material, 0.2C, 0.5C, 1C, 2C,
Specific discharge capacity under the multiplying power of 5C is respectively 176mAh/g, 165mAh/g, 156mAh/g, 146mAh/g, 121mAh/g.By
Again its specific capacity is recycled after circulation under 0.2C and is still maintained at 173mAh/g.
Comparative example 1 prepares common carbon-coated tertiary cathode material at voltage 4.3V, and discharge capacity is 176mAh/ for the first time
G, capacity is in 143mAh/g, capacity retention ratio 81.3% after 50 circulations.The high rate performance of ternary material, 0.2C,
Specific discharge capacity under the multiplying power of 0.5C, 1C, 2C, 5C be respectively 178mAh/g, 153mAh/g, 143mAh/g, 132mAh/g,
108mAh/g.Recycling its specific capacity under 0.2C again after circulation is 168mAh/g.
In the method for the preparation carbon coating nickel-cobalt-manganternary ternary anode material of above-described embodiment, using silica as intermediate
Protective layer, prevent carbon source discharged during high temperature cabonization reducibility gas reduction material of main part.The carbon coating layer of formation is bright
The aobvious electric conductivity for showing that conductive carbon is excellent improves the big electricity of battery compared with common carbon-coated tertiary cathode material
Charging and discharging capabilities are flowed, to improve high rate performance.
The above statement is only preferred embodiment of the invention, it is noted that those skilled in the art, not
Under the premise of being detached from the invention design, various modifications and improvements can be made, these also should be regarded as protection of the invention
Within the scope of.