CN108807933B - Positive electrode material and preparation method thereof - Google Patents
Positive electrode material and preparation method thereof Download PDFInfo
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- CN108807933B CN108807933B CN201810704189.0A CN201810704189A CN108807933B CN 108807933 B CN108807933 B CN 108807933B CN 201810704189 A CN201810704189 A CN 201810704189A CN 108807933 B CN108807933 B CN 108807933B
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- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
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- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H01M4/02—Electrodes composed of, or comprising, active material
- 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
- H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
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- 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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- H01M4/36—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
- H01M4/52—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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- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
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Abstract
The invention provides a positive electrode material which comprises a ternary material and a coating layer coated on the surface of the ternary material, wherein the coating layer comprises an organic flame-retardant material. According to the cathode material provided by the invention, the organic flame-retardant material is coated on the surface of the ternary material, so that the combustion of electrolyte is inhibited, the negative influence on the electrical property is avoided, and the thermal stability of the ternary cathode material and the electrochemical property of a battery are greatly improved. The invention also provides a preparation method of the cathode material, which comprises the following steps: taking a ternary material, and fully mixing the ternary material with a coating material in a solvent to obtain a mixed solution, wherein the coating material comprises an organic flame-retardant material; and carrying out spray drying on the mixed solution, and then carrying out mechanical fusion to obtain a ternary material coated by a coating layer, namely the anode material. The binding force between the coating layer and the ternary material can be further improved by adopting a mechanical fusion method.
Description
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a positive electrode material and a preparation method thereof.
Background
With the rapid growth of the new energy automobile industry, the market is more and more favored for high energy density batteries. The ternary anode material is continuously pursued in the market by virtue of high gram capacity and better cycle stability. However, the existing ternary cathode material has poor thermal stability, and will decompose and release oxygen at a temperature of about 200 ℃, and the heat generated by the oxygen and combustible electrolyte, carbon material, binder and the like in the battery will further aggravate the decomposition of the cathode, so as to cause thermal runaway, and deflagration will occur in a very short time, thus having a great safety risk.
At present, a coating layer is usually formed on the surface of the ternary cathode material to improve the thermal stability, and various materials are coated on the surface of the ternary cathode material to improve the thermal stability, but the improvement of the thermal stability of the cathode material is limited so far, and the requirement of the industry is not met.
Disclosure of Invention
In view of the above, the invention provides a cathode material and a preparation method thereof, and the organic flame retardant material is coated on the surface of the ternary material, so that the internal resistance of the battery is not reduced while the combustion of the electrolyte is inhibited, the negative influence on the electrical property is not generated, and the thermal stability of the ternary cathode material and the electrochemical property of the battery are greatly improved.
The invention provides a positive electrode material, which comprises a ternary material and a coating layer coated on the surface of the ternary material, wherein the coating layer comprises an organic flame-retardant material.
According to the cathode material provided by the first aspect of the invention, the organic flame-retardant material is coated on the surface of the ternary material, so that negative effects on electrical properties are not generated while electrolyte combustion is inhibited, and the thermal stability of the ternary cathode material and the electrochemical properties of a battery are greatly improved.
Wherein the material of the coating layer further comprises at least one of a nano inorganic material and an electrochemically active material.
The mass fraction of the coating layer in the cathode material is a, wherein 0< a is less than or equal to 20%.
The organic flame retardant material is a cyclotriphosphazene compound, and the cyclotriphosphazene compound comprises one or more of hexamethoxycyclotriphosphazene, hexaphenoxycyclotriphosphazene, hexamethylcyclotriphosphazene, hexap-formyl phenoxycyclotriphosphazene and ethoxy (pentafluoro) cyclotriphosphazene.
The nano inorganic material comprises one or more of aluminum oxide, zirconium oxide, cerium oxide, titanium oxide, barium titanate, silicon dioxide and conductive carbon black, and/or the electrochemical active material comprises one or more of lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadyl phosphate and lithium vanadyl fluorophosphate.
Wherein the pH value of the positive electrode material is 10.0-11.5.
The coating layer comprises uniformly dispersed organic flame-retardant materials, nano inorganic materials and electrochemical active materials, wherein the mass fractions of the organic flame-retardant materials, the nano inorganic materials and the electrochemical active materials in the anode material are b, c and d respectively, wherein b is more than 0 and less than or equal to 2%, c is more than 0 and less than or equal to 16%, and d is more than 0 and less than or equal to 2%.
The invention provides a preparation method of a cathode material, which comprises the following steps:
taking a ternary material, and fully mixing the ternary material with a coating material in a solvent to obtain a mixed solution, wherein the coating material comprises an organic flame-retardant material;
and carrying out spray drying on the mixed solution, and then carrying out mechanical fusion to obtain a ternary material coated by a coating layer, namely a positive electrode material, wherein the coating material comprises an organic flame-retardant material.
According to the preparation method of the cathode material provided by the second aspect of the invention, the ternary material powder coated by the coating material is obtained by spray drying. In addition, the binding force of the coating material and the ternary material is improved through a mechanical fusion method, so that the coating material is coated more tightly, the stacking density of the finally obtained anode material is improved, the specific capacity of the anode material is also improved, and the electrochemical stability of the anode material is improved. The preparation method provided by the invention is simple in process, low in cost, suitable for large-scale production and strong in practicability.
Wherein, the coating material also comprises at least one of nano inorganic material and electrochemical active material, and the preparation method specifically comprises the following steps:
taking a ternary material, fully mixing at least one of a nano inorganic material and an electrochemical active material with the ternary material and the organic flame-retardant material in a solvent to obtain a mixed solution, and performing spray drying and mechanical fusion on the mixed solution to obtain the cathode material.
Wherein the temperature of the spray drying is 80-250 ℃, and/or the rotating speed of the mechanical fusion is 3000-5500rpm, and the time of the mechanical fusion is 3-20 min.
Drawings
In order to more clearly illustrate the technical solution in the embodiment of the present invention, the drawings required to be used in the embodiment of the present invention will be described below.
FIG. 1 is a scanning electron micrograph of a positive electrode material in example 1 of the present invention;
FIG. 2 is a scanning electron micrograph of a raw material NCM523 used in example 1 of the present invention;
FIG. 3 is a scanning electron micrograph of the spray-dried material of example 1 according to the present invention;
FIG. 4 is a graph showing the charge and discharge test of the spray-dried material and the positive electrode material in example 1 of the present invention;
FIG. 5 is a scanning electron micrograph of the spray-dried material of example 2 according to the present invention;
FIG. 6 is a scanning electron micrograph of the positive electrode material in example 2 of the present invention.
Detailed Description
The following is a preferred embodiment of the present invention, and it should be noted that it is obvious to those skilled in the art that various modifications and improvements can be made without departing from the principle of the present invention, and these modifications and improvements are also considered to be within the scope of the present invention.
The positive electrode material provided by the embodiment of the invention comprises a ternary material and a coating layer coated on the surface of the ternary material, wherein the coating layer comprises an organic flame-retardant material.
The organic flame-retardant material can form a protective layer on the surface of the ternary material, so that the oxidation process of the ternary material is inhibited. In the abnormal use state, when a short circuit occurs inside the lithium ion battery, a high temperature is instantaneously generated. At the moment, the organic flame-retardant material is heated, absorbs heat and gasifies, so that the temperature of the combustible is reduced, the concentrations of the combustible vapor and the combustion-supporting gas are diluted, oxygen diffusion and heat transfer between a gas phase and a solid phase are reduced, violent reaction in a thermal runaway state of the battery is inhibited, combustion spread is prevented, and dangerous states such as explosion are prevented. And compared with inorganic flame retardant materials, the organic flame retardant materials do not have negative influence on the electrical properties.
According to the positive electrode material provided by the embodiment of the invention, the organic flame-retardant material is coated on the surface of the ternary material, so that the combustion of the electrolyte is inhibited, the negative influence on the electrical property is avoided, and the thermal stability of the ternary positive electrode material and the electrochemical property of the battery are greatly improved. In an embodiment of the present invention, the material of the coating layer further includes at least one of a nano inorganic material and an electrochemically active material. Specifically, the material of the coating layer may also be a nano inorganic material, an electrochemically active material, or a nano inorganic material and an electrochemically active material. The nano inorganic material can improve the thermal stability of the anode material, reduce the residual lithium on the surface layer and improve the cycle performance. The electrochemical active material can not only stabilize the heat of the anode material, but also prevent the ternary material from absorbing moisture in the environment to deteriorate, and improve the stability and the cycle performance of the anode material. Preferably, the material of the coating layer includes an organic flame retardant material, a nano inorganic material and an electrochemically active material. Through the synergistic effect of the three components, the advantages of the three components are complemented, and the performances of the anode material such as thermal stability, cycle performance, specific capacity and rate can be greatly improved.
In the embodiment of the invention, the mass fraction of the coating layer in the cathode material is a, wherein a is more than 0 and less than or equal to 20%. The content of the coating layer is not too high, and if the content of the coating layer is too high, the thickness of the coating layer is too thick, and the transportation of ions or electrons in the charge and discharge process of the positive electrode material is hindered. And the mass fraction of the ternary material in the positive electrode material can also be seen as e from the mass fraction of the coating layer, wherein e is more than or equal to 80% and less than 100%. Preferably, 3. ltoreq. a.ltoreq.17%. More preferably, 8. ltoreq. a.ltoreq.14%.
In the embodiment of the present invention, the thickness of the coating layer can be set according to actual needs, for example, the thickness of the coating layer can be in the nanometer range, specifically, 50 to 2000 nm.
In the embodiment of the invention, the organic flame retardant material is a cyclotriphosphazene compound, and the cyclotriphosphazene compound comprises one or more of hexamethoxycyclotriphosphazene, hexaphenoxycyclotriphosphazene, hexamethylcyclotriphosphazene, hexap-aldehyde phenoxycyclotriphosphazene and ethoxy (pentafluoro) cyclotriphosphazene.
The cyclotriphosphazene compound is one of organic flame retardant materials, and is also the best one suitable for a positive electrode material. The flame retardant mechanism of the cyclotriphosphazene compound is shown as the comprehensive action of four ways, firstly, the heat absorption during the pyrolysis of the phosphazene is a cooling mechanism; phosphoric acid, metaphosphoric acid and polyphosphoric acid generated by thermal decomposition of the composite material can form a layer of non-volatile protective film on the surface of the polymer material to isolate air, which is an isolating film mechanism; secondly, gases such as carbon dioxide, ammonia gas, nitrogen gas, water vapor and the like are released after being heated at the same time, which is a dilution mechanism; third, these non-combustible gases block the oxygen supply and achieve flame retardant synergy and synergy, and fourth, the polymers burn with the formation of PO groups which combine with the H, HO reactive groups in the flame zone and act as a flame suppressor, which is a chain termination reaction mechanism. Due to the synergistic effect, the system shows good flame retardant property, and the thermal stability of the ternary cathode material is further improved.
In an embodiment of the present invention, the nano inorganic material includes one or more of alumina, zirconia, ceria, titania, barium titanate, silica, and conductive carbon black. Optionally, the conductive carbon black includes C45 or the like.
In an embodiment of the present invention, the electrochemically active material includes one or more of lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadyl phosphate, and lithium vanadium fluorophosphate.
In the embodiment of the invention, the positive electrode material comprises a nickel cobalt lithium manganate ternary material or a nickel cobalt lithium aluminate ternary material; the molecular formula of the nickel cobalt lithium manganate ternary material is LiNi(1-x1-y1)Cox1Mny1O2Wherein x is more than or equal to 0.11≤0.4、0.1≤y1Less than or equal to 0.4, and the molecular formula of the nickel cobalt lithium aluminate ternary material is LiNi(1-x2-y2)Cox2Aly2O2Wherein x is more than or equal to 0.12≤0.15、0.05≤y2≤0.1。
In an embodiment of the present invention, the particle size of the nano inorganic material is 8 to 60nm, and/or the particle size of the electrochemical active material is 30 to 200 nm. Preferably, the nano inorganic material has a particle size of 15 to 40nm, and/or the electrochemically active material has a particle size of 50 to 170 nm. More preferably, the nano inorganic material has a particle size of 20 to 30nm, and/or the electrochemically active material has a particle size of 80 to 130 nm.
In an embodiment of the present invention, the carbon content of the electrochemically active material is 0.5% to 2%. The carbon element in the electrochemically active material affects the specific capacity of the positive electrode material. Therefore, the specific capacity of the anode material can be greatly improved by the carbon content of 0.5-2%. Preferably, the carbon content of the electrochemically active material is 0.8% to 1.6%. More preferably, the carbon content of the electrochemically active material is 1.1% to 1.3%.
In the embodiment of the invention, the pH value of the cathode material is 10.0-11.5. According to the invention, the organic flame-retardant material or the organic flame-retardant material and at least one of the nano inorganic material and the electrochemical active material are coated on the surface of the ternary material, so that the pH value of the anode material can be greatly reduced, the later processing of the anode material is facilitated, and the later mixing process is not easy to form a jelly shape. Optionally, the positive electrode material has a pH of 10.2-10.8. When the material of the cladding layer also includes an electrochemically active material, the electrochemically active material may further lower the pH of the positive electrode material. Further optionally, the pH of the positive electrode material is 10.4-10.6.
In an embodiment of the invention, the material of the coating layer comprises an organic flame-retardant material, a nano inorganic material and an electrochemical active material which are uniformly dispersed, wherein the mass fractions of the organic flame-retardant material, the nano inorganic material and the electrochemical active material in the cathode material are b, c and d respectively, wherein 0< b > is less than or equal to 2%, 0< c > is less than or equal to 16%, and 0< d > is less than or equal to 2%. According to the invention, the three materials, namely the organic flame-retardant material, the nano inorganic material and the electrochemical active material, exist and are coated on the surface of the ternary material, and the advantages of the three materials are complemented mutually through the synergistic effect of the three materials, so that the performances of the anode material, such as thermal stability, cycle performance, specific capacity, multiplying power and the like, can be greatly improved.
The preparation method of the cathode material provided by the embodiment of the invention comprises the following steps:
step 1: taking a ternary material, and fully mixing the ternary material and a coating material in a solvent to obtain a mixed solution; the coating material comprises an organic flame retardant material;
step 2: and carrying out spray drying on the mixed solution, and then carrying out mechanical fusion to obtain a ternary material coated by a coating layer, namely the anode material.
According to the preparation method of the cathode material provided by the embodiment of the invention, the ternary material powder coated by the coating material is obtained by spray drying. In addition, the binding force of the coating material and the ternary material is improved through a mechanical fusion method, so that the coating material is coated more tightly, the stacking density of the finally obtained anode material is improved, the specific capacity of the anode material is also improved, and the electrochemical stability of the anode material is improved. The preparation method provided by the invention is simple in process, low in cost, suitable for large-scale production and strong in practicability.
In an embodiment of the invention, the solvent comprises a liquid phase dispersant. The liquid phase dispersant includes one or more of N-methyl pyrrolidone (NMP), ethanol, and water.
In an embodiment of the present invention, the temperature of the spray drying is 80 to 250 ℃, and/or the pressure of the nozzle during the spray drying is 0.1 to 0.5 MPa.
In the embodiment of the invention, the rotation speed of mechanical fusion is 3000-5500rpm, and the time of mechanical fusion is 3-20 min.
In an embodiment of the present invention, the material of the coating layer further includes at least one of a nano inorganic material and an electrochemically active material, and the preparation method specifically includes the following steps:
taking a ternary material, fully mixing at least one of a nano inorganic material and an electrochemical active material with the ternary material and an organic flame-retardant material in a solvent to obtain a mixed solution, and performing spray drying and mechanical fusion on the mixed solution to obtain the cathode material.
The embodiment of the invention also provides a preparation method when the material of the coating layer is organic flame-retardant material and at least one of nano inorganic material and electrochemical active material, the process is simple, the cost is low, and the preparation method is suitable for large-scale production and has strong practicability.
The following will further describe the embodiments of the present invention by dividing into a plurality of examples.
Example 1
A preparation method of a positive electrode material comprises the following steps:
step 1: adding NCM523, aluminum oxide, lithium iron phosphate and hexaphenoxycyclotriphosphazene into an ethanol solution according to the mass ratio of NCM523 to aluminum oxide to lithium iron phosphate to hexaphenoxycyclotriphosphazene of 95:1:3:1, uniformly dispersing, and fully mixing to obtain a mixed solution. And then drying the mixed solution at the temperature of 150 ℃ in spray drying equipment, wherein the pressure of a spray dryer nozzle is 0.2MPa, so as to obtain the NCM523 coated by the aluminum oxide, the lithium iron phosphate and the hexaphenoxycyclotriphosphazene.
Step 2: weighing 350g of NCM523 coated by the aluminum oxide prepared in the step 1, the lithium iron phosphate and the hexaphenoxycyclotriphosphazene, and fusing and processing for 5min in a mechanical fusion machine at the rotating speed of 5000rpm to obtain the anode material, wherein the NCM523@ A is used for expressing.
Example 2
A preparation method of a positive electrode material comprises the following steps:
step 1: adding NCM622, C45, lithium manganese phosphate and ethoxy (pentafluoro) cyclotriphosphazene into an ethanol solution according to the mass ratio of NCM622: C45: lithium manganese phosphate: ethoxy (pentafluoro) cyclotriphosphazene (93: 1:5: 1) to be uniformly dispersed, and fully mixing to obtain a mixed solution. And then drying the mixed solution at the temperature of 150 ℃ under a spray drying device, wherein the pressure of a spray dryer nozzle is 0.5MPa, so as to obtain the NCM622 coated by the C45, the lithium ferric manganese phosphate and the ethoxy (pentafluoro) cyclotriphosphazene.
Step 2: weighing 350g of NCM622 coated by the C45 prepared in the step 1, lithium ferric manganese phosphate and ethoxy (pentafluoro) cyclotriphosphazene, and fusing and processing for 10min in a mechanical fusing machine at the rotating speed of 4000rpm to obtain a positive electrode material, wherein the NCM622@ A is used for expressing.
Example 3
A preparation method of a positive electrode material comprises the following steps:
step 1: adding NCM622 and hexamethylcyclotriphosphazene into an N-methylpyrrolidone solution according to the mass ratio of NCM622 to hexamethylcyclotriphosphazene of 93:7, uniformly dispersing, and fully mixing to obtain a mixed solution. And then drying the mixed solution at the temperature of 150 ℃ under a spray drying device, wherein the pressure of a spray dryer nozzle is 0.1MPa, so as to obtain the NCM622 coated by both hexamethylcyclotriphosphazene.
Step 2: and (2) weighing 350g of NCM622 coated by the hexamethylcyclotriphosphazene prepared in the step (1), and fusing and processing for 7min in a mechanical fusing machine at the rotating speed of 4500rpm to obtain the cathode material.
Example 4
A preparation method of a lithium ion button battery comprises the following preparation steps:
step 1: adding the positive electrode material, polyvinylidene fluoride and the conductive agent prepared in the example 1 into an NMP solvent according to the mass ratio of 93:3:4, performing ball milling and stirring to obtain slurry, uniformly coating the slurry on the surface of an aluminum foil, sequentially rolling the aluminum foil coated with the slurry, and performing vacuum drying at the temperature of 110 ℃ for 12 hours to obtain a positive electrode;
step 2: and assembling the electric anode, the polypropylene microporous diaphragm, the lithium sheet cathode and an electrolyte into the button battery, wherein the electrolyte comprises ethylene carbonate, methyl ethyl carbonate and hexafluorophosphoric acid. The volume ratio of ethylene carbonate to methyl ethyl carbonate is 3:7, and the LiPF content is 1mol/L6。
Example 5
A preparation method of a lithium ion button battery comprises the following preparation steps:
step 1: adding the positive electrode material, polyvinylidene fluoride and the conductive agent prepared in the example 2 into an NMP solvent according to the mass ratio of 93:3:4, mixing the positive electrode material, the polyvinylidene fluoride and the conductive agent into the NMP solvent by ball milling and stirring to form slurry, then uniformly coating the slurry on the surface of an aluminum foil, sequentially rolling the aluminum foil coated with the slurry, and performing vacuum drying at the temperature of 110 ℃ for 12 hours to obtain a positive electrode;
step 2: and assembling the electric anode, the polypropylene microporous diaphragm, the lithium sheet cathode and an electrolyte into the button battery, wherein the electrolyte comprises ethylene carbonate, methyl ethyl carbonate and hexafluorophosphoric acid. The volume ratio of ethylene carbonate to methyl ethyl carbonate is 3:7, and the LiPF content is 1mol/L6。
Please refer to fig. 1-3, and fig. 5-6. It can be seen from the figure that the ternary material surface forms a coating structure after the spray drying and mechanofusion method. And the bonding between the cladding layer and the ternary material becomes tighter after the mechanofusion process.
Effects of the embodiment
First, the button cell prepared by the method of example 4 using the positive electrode material of example 1 as a raw material was left at room temperature for 24 hours and then subjected to a charge and discharge test, wherein the material after spray drying was sample a, and the finally obtained positive electrode material was sample b. The charging and discharging voltage was 2.7-4.35V, and the result is shown in FIG. 4.
Next, the button cell prepared by the method of example 4 using the positive electrode material of example 1 as a raw material, the button cell prepared by example 5 using the positive electrode material of example 2 as a raw material, and the button cell prepared by the uncoated positive electrode material were charged, the button cell was disassembled after being fully charged, the powder material of the positive electrode tab was collected, Differential Scanning Calorimetry (DSC) test analysis was performed using a TA thermal analysis Q200 instrument in the united states, and the initial heat release temperature, peak temperature, and heat release Q of the heat release peak of each sample were collected, and the results are shown in table 1.
Finally, the pH of the anode material was tested using the standard of national GBT 1717-.
Table 1: thermal stability of positive electrode materials with and without coating
Table 2: pH change of coated and uncoated cathode materials
| Sample (I) | NCM523 | NCM523@A | NCM622 | NCM622@A |
| pH value | 11.7 | 10.5 | 11.9 | 10.2 |
First, as can be seen from fig. 4, the specific capacity of the mechanically fused sample b is higher at the charging and discharging voltage of 3.5 to 4V. Therefore, the mechanical fusion can improve the binding force between the coating layer and the ternary material, and the coating material in the coating layer and the ternary material are combined more tightly after the mechanical fusion, so that the contact area is increased, the polarization is reduced, and finally the specific capacity of the anode material is improved to a certain extent.
Next, as can be seen from fig. 2, the heat release of the positive electrode materials of examples 1 and 2 having the coating layer was lower than that of the raw materials of examples 1 and 2 which were not coated, and the starting temperature and the peak temperature were higher. Therefore, the stability of the cathode material can be effectively improved by coating the organic flame-retardant material, the inorganic nano material and the electrochemical active material on the surface of the ternary material.
Finally, the pH of the positive electrode materials of examples 1 and 2 with a coating layer was lower than the pH of the raw materials of examples 1 and 2 without coating. Therefore, the organic flame-retardant material, the inorganic nano material and the electrochemical active material are coated on the surface of the ternary material, so that the pH value of the material can be effectively reduced, and the later processing in the preparation of the button cell is facilitated.
The foregoing detailed description is provided for the purposes of illustrating the embodiments of the present invention, and is provided for the purposes of illustrating the principles and embodiments of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.
Claims (8)
1. The anode material is characterized by comprising a ternary material and a coating layer coated on the surface of the ternary material, wherein the coating layer comprises uniformly dispersed organic flame-retardant material, nano inorganic material and electrochemical active material, the organic flame-retardant material is a cyclotriphosphazene compound, the nano inorganic material comprises one or more of alumina, zirconia, cerium oxide, titanium oxide, barium titanate, silica and conductive carbon black, the mass fractions of the organic flame-retardant material, the nano inorganic material and the electrochemical active material in the anode material are respectively b, c and d, wherein b is more than 0 and less than or equal to 2%, c is more than 0 and less than or equal to 16%, and d is more than 0 and less than or equal to 2%.
2. The positive electrode material according to claim 1, wherein the mass fraction of the clad layer in the positive electrode material is a, wherein 0< a ≦ 20%.
3. The positive electrode material according to claim 1, wherein the cyclotriphosphazene-based compound comprises one or more of hexamethoxycyclotriphosphazene, hexaphenoxycyclotriphosphazene, hexamethylcyclotriphosphazene, hexap-formyl phenoxycyclotriphosphazene and ethoxy (pentafluoro) cyclotriphosphazene.
4. The positive electrode material of claim 1, wherein the electrochemically active material comprises one or more of lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadyl phosphate, and lithium vanadyl fluorophosphate.
5. The positive electrode material according to claim 1, wherein the positive electrode material has a pH of 10.0 to 11.5.
6. The preparation method of the cathode material is characterized by comprising the following steps of:
taking a ternary material, and fully mixing the ternary material with a coating material in a solvent to obtain a mixed solution, wherein the coating material comprises an organic flame-retardant material, a nano inorganic material and an electrochemical active material, the organic flame-retardant material is a cyclotriphosphazene compound, and the nano inorganic material comprises one or more of alumina, zirconia, cerium oxide, titanium oxide, barium titanate, silicon dioxide and conductive carbon black;
and performing spray drying on the mixed solution, and then performing mechanical fusion to obtain a ternary material coated by a coating layer, namely a positive electrode material, wherein the mass fractions of the organic flame-retardant material, the nano inorganic material and the electrochemical active material in the positive electrode material are b, c and d respectively, wherein b is more than 0 and less than or equal to 2%, c is more than 0 and less than or equal to 16%, and d is more than 0 and less than or equal to 2%.
7. The method of claim 6, wherein the temperature of the spray drying is 80-250 ℃.
8. The method according to claim 6, wherein the rotation speed of the mechanofusion is 3000-5500rpm, and the time of the mechanofusion is 3-20 min.
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