CN111916701B - Coated positive electrode material and preparation method and application thereof - Google Patents
Coated positive electrode material and preparation method and application thereof Download PDFInfo
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Abstract
The invention relates to a coated anode material and a preparation method and application thereof, wherein the preparation method comprises the steps of adding a coated metal source into a complexing solution, mixing and heating to obtain gel, then adding the anode material into the gel, mixing and calcining to obtain the coated anode material, wherein the coated metal source comprises a cobalt source, a manganese source and an aluminum source; the preparation method provided by the invention adopts the sol-gel method, so that residual alkali on the surface of the anode material can be effectively reduced, the coating layer of the obtained coated anode material has electronic conductivity, the contact area of the anode material and electrolyte can be effectively reduced, side reactions are reduced, and the electrochemical performance of the anode material is improved.
Description
Technical Field
The invention belongs to the field of battery materials, and relates to a coated positive electrode material, and a preparation method and application thereof.
Background
In order to make up for the deficiency of lithium in the material of the positive electrode caused by the volatilization of the lithium source in the calcination process in the synthesis process of the positive electrode material, the proportion of lithium is properly increased in the process of mixing the precursor of the positive electrode material with the lithium source, but in the preparation process of the positive electrode material, the body and the excessive lithium source of the positive electrode material can be contacted with water and carbon dioxide in the air to generate lithium hydroxide and lithium carbonate, namely residual alkali; too high residual alkali easily causes the pH value of the anode material to rise, so that the anode material is more easily affected with moisture and absorbs water, and PVDF is easily agglomerated, so that the viscosity of the battery slurry is increased, the battery slurry is in a gel state, and the battery slurry cannot enter the next procedure, thereby reducing the influence of the residual alkali on the anode material.
CN111370684A discloses a method for reducing the residual alkali content on the surface of a high-nickel cathode material of a lithium ion battery, which comprises the following steps: adding a certain amount of acid or acid derivative into a certain amount of non-aqueous active hydrogen-free organic solvent at the normal temperature at the stirring speed of 1-10 m/s, and stirring until the acid or acid derivative is completely dissolved to obtain a washing solution for reducing the residual alkali on the surface of the high-nickel anode material of the lithium ion battery; wherein the mass ratio of the high-nickel anode material to be treated to the non-aqueous active hydrogen-free organic solvent is 1: 0.5-1: 4; the molar concentration of the acid or the acid derivative in the washing liquid is 0.5-1.5 times of the molar quantity of residual alkali on the surface of the high-nickel anode material to be treated; adding a high-nickel anode material to be treated into the washing liquid under stirring at a linear speed of 1-10 m/s, and stirring for 1-120 min; centrifuging to remove the solvent, and then vacuumizing, heating and drying at 20-80 ℃ to obtain the treated high-nickel cathode material; CN108878863A discloses a method for improving the surface residual alkalinity of a ternary positive electrode material of a lithium ion battery, which comprises the following steps: mixing a powder nickel-cobalt-manganese layered positive electrode material with a molecular formula of LiNiCoMnO with water, and centrifugally separating to obtain a washed powder material; adding a lithium source into absolute ethyl alcohol, uniformly mixing, adding a washed powder material, uniformly mixing, completely evaporating, drying and sintering to obtain a ternary cathode material of the lithium ion battery; the scheme adopts a washing method to reduce the residual alkali on the surface of the anode material, the operation process is complex, and the adverse effect on the electrical property of the anode material is easy to cause.
Therefore, it is still significant to develop a method for preparing a positive electrode material, which can effectively reduce the residual alkali of the positive electrode material and can obtain the positive electrode material with excellent first effect and cycle retention rate.
Disclosure of Invention
The invention aims to provide a coated positive electrode material and a preparation method and application thereof, wherein the preparation method comprises the steps of adding a coated metal source into a complexing solution, mixing and heating to obtain a gel, then adding the positive electrode material into the gel, mixing and calcining to obtain the coated positive electrode material, wherein the coated metal source comprises a cobalt source, a manganese source and an aluminum source; the preparation method provided by the invention adopts the sol-gel method, so that residual alkali on the surface of the anode material can be effectively reduced, the coating layer of the obtained coated anode material has electronic conductivity, the contact area of the anode material and electrolyte can be effectively reduced, side reactions are reduced, and the electrochemical performance of the anode material is improved.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a method for preparing a coated cathode material, the method comprising:
adding the coating metal source into the complexing solution, mixing and heating to obtain gel; and
adding a positive electrode material into the gel, mixing and calcining to obtain the coated positive electrode material;
wherein the cladding metal source comprises a cobalt source, a manganese source and an aluminum source.
The positive electrode material refers to a positive electrode material obtained by sintering a positive electrode material precursor and a lithium source; when the content of residual alkali is higher, the pH value of the anode material is easy to rise, so that the anode material is easier to damp and absorb water, and the caking agent (such as PVDF) is easy to agglomerate, so that the viscosity of the battery slurry is increased and the battery slurry is in a gel state, and the next working procedure cannot be performed; in order to solve the problems, reduce the residual alkali on the surface of the sintered positive electrode material and improve the electrical property of the positive electrode material, the method takes a coating metal source containing a cobalt source, a manganese source and an aluminum source as a raw material to form a metal oxide (such as Mn (AlCo) containing cobalt, manganese and aluminum) by a sol-gel method2)2O8) Which can react with residual alkali on the surface of the positive electrode material (e.g., react to form Li)2Mn(AlCo2)2O9) Further reducing residual alkali on the surface of the anode material; and the formed cladding layer has electronic conductivity; meanwhile, the existence of the coating layer in the coated anode material obtained by the preparation method reduces the contact area between the anode material and the electrolyte, thereby reducing the occurrence of side reactions and further improving the electrochemical performance of the material; compared with a pure anode material, the coated anode material obtained by the method provided by the invention has the advantages that the cycle retention rate is obviously improved, and the service life is prolonged.
Preferably, the ratio of the molar amount of the cobalt source to the volume of the complexing solution is 0.15-0.35mol/L, such as 0.2mol/L or 0.25mol/L and the like.
Preferably, the ratio of the molar amount of the manganese source to the volume of the complexing solution is 0.03 to 0.06mol/L, such as 0.04mol/L or 0.05mol/L and the like.
Preferably, the ratio of the molar amount of the aluminum source to the volume of the complexing solution is 0.005 to 0.15mol/L, such as 0.01mol/L, 0.03mol/L, 0.05mol/L, 0.07mol/L, 0.1mol/L, or 0.13mol/L, and the like.
When the concentration of the coating metal source is not in the range, if the concentration is too low, the coating cannot be sufficiently reacted with the residual alkali on the surface of the positive electrode material and the contact area of the positive electrode material and the electrolyte cannot be reduced better; if the concentration is too high, the metal oxide containing cobalt, manganese and aluminum is formed too much by the sol-gel method, so that the coating layer is too thick, and lithium ion conduction of the positive electrode material in the charging and discharging processes is not facilitated, and the electrochemical performance is reduced.
Preferably, the molar ratio of the cobalt source, the manganese source and the aluminum source in the coating metal source is (15-35): (3-6): (0.5-15), such as 15:6:1, 20:5:5 or 30:4:10, etc.
Preferably, the molar ratio of the cobalt source, the manganese source and the aluminum source in the coating metal source is (3-5):1 (1-3), preferably 4:1: 2.
Here, the coating metal source adopts the above-mentioned composition, which generates Mn (Al) in the sol-gel processmCon)2O8(m is selected from 3 to 5, for example, 3.5, 4 or 4.5, etc., and n is selected from 1 to 2, for example, 1.2, 1.5 or 1.8, etc.) and further reacted with residual alkali to produce Li2Mn(AlmCon)2O9Thereby reducing residual alkali and improving the electrochemical performance.
Preferably, the complexing solution comprises Ethylenediaminetetraacetic acid (EDTA), NH3And water.
Preferably, EDTA, NH3The ratio of the molar amount of water to the molar amount of water is (0.025-0.065) to (0.8-1.05) to (5-7), for example 0.03:1:5.5, 0.05:0.9:6 or 0.06:0.85: 6.5.
The sol-gel method of the invention adopts the composition of the complexing solution, and mixes the complexing solution with the coating metal source, wherein water is used as the solvent of the complexing solution for dissolving the complexing agent, NH3As main complexing agent, EDTA as auxiliary complexing agent, NH3And EDTA adsorbs metal ions in the metal source to form a metal ion complex, the complex and residual alkali (lithium hydroxide and lithium carbonate) on the surface of the anode material are subjected to chemical reaction to generate lithium manganese aluminum cobaltate, the residual alkali content of the anode material is effectively reduced, the formed coating layer has electronic conductivity, and meanwhile, the contact area of the anode material and electrolyte is reduced due to the existence of the coating layer, so that the electrochemical performance of the anode material is improved, and the cycle performance of the anode material is further improved.
Preferably, the chemical general formula of the cathode material is LixNiaCobMncAldMyO2Wherein 1.00. ltoreq. x.ltoreq.1.50, e.g. 1.1, 1.2, 1.3 or 1.4 etc., 0. ltoreq. y.ltoreq.0.02, e.g. 0.005, 0.01 or 0.015 etc., 0. ltoreq. a.ltoreq.0.90, e.g. 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7 or 0.8 etc., 0. ltoreq. b.ltoreq.0.06, e.g. 0.01, 0.02, 0.03, 0.04 or 0.05 etc., 0. ltoreq. c.ltoreq.0.03, e.g. 0.01 or 0.02 etc., 0. ltoreq. d.ltoreq.0.03, e.g. 0.01 or 0.02 etc., a + b + c + d.ltoreq.1; m comprises at least one of Y, Sr, Mo, La, Zr, Ti, Mg, B, Nb, Ba, Si, P and W.
Preferably, the heating temperature is 60-80 ℃, such as 65 ℃, 70 ℃ or 75 ℃, and the like.
According to the invention, the coating metal source and the complexing solution are mixed and then heated at the temperature to form gel, which is beneficial to forming a uniform gel system and is more beneficial to reacting with residual alkali on the surface of the anode material, when the temperature is too low, partial reaction is incomplete, so that the uniformity of the system is poor, and when the temperature is too high, the energy consumption is high, the ammonia volatilization loss is large, and the system balance is not facilitated.
Preferably, the heating time is 5-6h, such as 5.5h, etc.
Preferably, drying is also included after the mixing and before the calcining.
Preferably, the drying is vacuum drying.
Preferably, the drying temperature is 150-.
Preferably, the drying time is ≧ 15h, such as 18h, 20h or 24h, or the like.
Preferably, the temperature of the calcination is 400-600 ℃, such as 450 ℃, 500 ℃ or 550 ℃, and the like.
In the invention, the calcination is carried out at the temperature, which is beneficial to coating the coating formed by the sol-gel method on the surface of the anode material, and when the temperature is too high, the coating layer enters the inside of the anode material and cannot achieve the coating effect; when the temperature is too low, the coating material cannot be firmly coated on the surface of the cathode material.
Preferably, the calcination time is 0.5 to 1h, such as 0.6h, 0.7h, 0.8h, or 0.9h, and the like.
Preferably, the atmosphere of the calcination is an oxygen atmosphere.
Preferably, the preparation method of the cathode material comprises the following steps:
and mixing the precursor with a lithium source, and sintering to obtain the cathode material.
Preferably, the chemical formula of the precursor is NiaCobMncAldMy(OH)2Wherein 1.00. ltoreq. x.ltoreq.1.50, e.g. 1.1, 1.2, 1.3 or 1.4 etc., 0. ltoreq. y.ltoreq.0.02, e.g. 0.005, 0.01 or 0.015 etc., 0. ltoreq. a.ltoreq.0.90, e.g. 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7 or 0.8 etc., 0. ltoreq. b.ltoreq.0.06, e.g. 0.01, 0.02, 0.03, 0.04 or 0.05 etc., 0. ltoreq. c.ltoreq.0.03, e.g. 0.01 or 0.02 etc., 0. ltoreq. d.ltoreq.0.03, e.g. 0.01 or 0.02 etc., a + b + c + d.ltoreq.1; m comprises at least one of Y, Sr, Mo, La, Zr, Ti, Mg, B, Nb, Ba, Si, P and W.
Preferably, the lithium source is selected from lithium hydroxide.
Preferably, the method of mixing the precursor with the lithium source is dry mixing.
Preferably, the molar ratio of precursor to lithium source is 1:1 to 1:1.50, such as 1:1.3, 1:1.5, 1:1.10, 1:1.20, 1:1.30, or 1:1.40, etc.
Preferably, the sintering temperature is 700-900 ℃, such as 750 ℃, 800 ℃ or 850 ℃ and the like.
Preferably, the sintering time is 8-15h, such as 9h, 10h, 11h, 12h, 13h or 14h, etc.
Preferably, the atmosphere of the sintering is an oxygen atmosphere.
Preferably, the sintering process further comprises cooling, crushing and sieving to obtain the cathode material.
As a preferable technical solution of the present invention, the method for preparing the coated cathode material includes:
dry mixing the precursor and lithium hydroxide according to the molar weight ratio of 1:1-1:1.50, sintering at the temperature of 700-900 ℃ in an oxygen atmosphere for 8-15h, cooling, crushing and sieving to obtain a positive electrode material; and
according to the molar ratio of EDTA to NH3Preparing a complex solution by water according to the proportion of (0.025-0.065) to (0.8-1.05) to (5-7); and
adding a cobalt source, a manganese source and an aluminum source into the complexing solution, stirring to form a red solution, and stirring and heating at 60-80 ℃ for 5-6 hours to obtain dark red gel; and
adding the anode material into dark red gel, uniformly stirring, then placing the gel in a vacuum drying box with the temperature of 150-.
In a second aspect, the invention provides a coated cathode material prepared by the preparation method of the first aspect, wherein the coated cathode material comprises a cathode material and a coating layer located on the surface of the cathode material.
Preferably, the molar ratio of cobalt, manganese and aluminum in the coating layer is (15-35) to (3-6) to (0.5-15), such as 15:6:1, 20:5:5 or 30:4: 10.
In a third aspect, the present invention provides a battery comprising the encapsulated positive electrode material according to the second aspect.
Compared with the prior art, the invention has the following beneficial effects:
(1) according to the invention, a coating metal source containing a cobalt source, a manganese source and an aluminum source is used as a raw material, the raw material is mixed with a complexing solution to form gel, and then the gel is mixed with a positive electrode material to react, so that residual alkali on the surface of the positive electrode material is consumed, the content of the residual alkali on the surface of the positive electrode material is reduced, and a coating layer is formed on the surface of the positive electrode material and has electronic conductivity;
(2) according to the invention, the coating layer is formed on the surface of the anode material by a sol-gel method, so that the contact area of the anode material and the electrolyte is reduced, the side reaction is reduced, and the electrochemical performance is improved.
Drawings
FIG. 1 is a flow chart of a preparation process of the coated cathode material of the present invention;
FIG. 2 is a scanning electron microscope image of the coated cathode material prepared in example 1 of the present invention;
fig. 3 is a scanning electron microscope image of the coated positive electrode material prepared in comparative example 1 of the present invention.
Detailed Description
The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
The flow chart of the preparation process of the coated cathode material is shown in fig. 1, and as can be seen from fig. 1, the preparation process comprises the following steps:
preparing a complexing solution: the complexing solution contains EDTA and NH3And water; wherein NH3By NH3·H2O is added in the form of, and
adding a source of a coating metal to the complexing solution, the source of the coating metal comprising a source of cobalt (e.g., Co (NO)3)2·6H2O), manganese sources (e.g. Mn (NO)3)2·6H2O) and an aluminum source (e.g., Al (NO)3)3·9H2O); stirring and heating for a certain time; a dark red gel with high viscosity (Mn (Al) in the gel) was obtainedmCon)2O8) And
and adding a positive electrode material (for example, a primary sintered positive electrode material obtained by mixing a precursor with a lithium source and performing primary sintering) into the dark red gel, uniformly stirring, drying in vacuum, and calcining in an oxygen atmosphere to obtain the sol-gel coated positive electrode material.
Example 1
The preparation method of the coated positive electrode material comprises the following steps:
(1) the precursor Ni0.88Co0.06Mn0.03Al0.03(OH)2Dry mixing with lithium hydroxide according to the mol ratio of 1:1.03, primary sintering for 10 hours at 800 ℃ in an oxygen atmosphere, cooling, crushing and sieving to obtain primary sintered polycrystalline anode material Li1.03Ni0.88Co0.06Mn0.03Al0.03O2；
(2) According to the molar ratio of EDTA to NH3:H2Mixing the three components uniformly to prepare 100mL of complex solution, wherein O (deionized water) is 0.06:1: 5.5;
(3) 0.005mol of Mn (NO)3)2·6H2O、0.01molAl(NO3)3·9H2O and 0.02mol Co (NO)3)2·6H2Adding O into the complex solution, stirring to obtain red solution, and heating at 80 deg.C for 5 hr to obtain high-viscosity dark red gel Mn (AlCo)2)2O8；
(4) Adding 100g of the polycrystalline anode material obtained in the step (1) into the gel solution, uniformly stirring, drying in a vacuum drying oven at 200 ℃ for 15h, calcining at 400 ℃ in an oxygen atmosphere for 0.5h, and cooling to room temperature to obtain a coated anode material Li1.03Ni0.88Co0.06Mn0.03Al0.03(Mn0.03Al0.06Co0.12)O2。
Example 2
This example differs from example 1 in that the amount of addition of the manganese source, aluminum source and cobalt source was replaced with 0.003mol of Mn (NO)3)2·6H2O、0.015molAl(NO3)3·9H2O and 0.015mol Co (NO)3)2·6H2O; other parameters and conditions were exactly the same as in example 1.
Example 3
This example differs from example 1 in that the amounts of manganese, aluminum and cobalt sources added were replaced with 0.006mol of Mn (NO)3)2·6H2O、0.0005molAl(NO3)3·9H2O and 0.035mol Co (NO)3)2·6H2O; other parameters and conditions were exactly the same as in example 1.
Example 4
This example differs from example 1 in that the calcination temperature in step (4) was replaced with 600 ℃ and the other parameters and conditions were exactly the same as in example 1.
Example 5
This example differs from example 1 in that the calcination temperature in step (4) was replaced with 700 ℃ and the other parameters and conditions were exactly the same as in example 1.
Example 6
This example differs from example 1 in that the complexing solution is EDTA-NH3The molar ratio of water was 0.025:1.05:5, and the other parameters and conditions were exactly the same as in example 1.
Example 7
This example differs from example 1 in that the complexing solution is EDTA-NH3The molar ratio of water was 0.065:0.8:7, and other parameters and conditions were exactly the same as in example 1.
Example 8
This example differs from example 1 in that the complexing solution is EDTA-NH3The molar ratio of water was 0.02:1.1:4.5, and other parameters and conditions were exactly the same as in example 1.
Example 9
This example differs from example 1 in that the complexing solution is EDTA-NH3The molar ratio of water was 0.075:0.7:8, and the other parameters and conditions were exactly the same as in example 1.
Comparative example 1
The precursor Ni0.88Co0.06Mn0.03Al0.03(OH)2Mixing with lithium hydroxide at a molar ratio of 1:1.03 by dry method at 800 deg.C in oxygen atmosphereIn the method, primary sintering is carried out for 10 hours, and the primary sintered polycrystalline anode material Li is obtained by cooling, crushing and sieving1.03Ni0.88Co0.06Mn0.03Al0.03O2。
Comparative example 2
This comparative example differs from example 1 in that the clad metal source does not contain Mn (NO)3)2·6H2O, i.e. addition of only 0.015mol Al (NO)3)3·9H2O and 0.02mol Co (NO)3)2·6H2O, other parameters and conditions were exactly the same as those in example 1.
Comparative example 3
This comparative example differs from example 1 in that the coating metal source does not contain Al (NO)3)3·9H2O, addition of only 0.015mol of Mn (NO)3)2·6H2O、0.02mol Co(NO3)2·6H2O, other parameters and conditions were exactly the same as those in example 1.
Comparative example 4
This comparative example differs from example 1 in that the coating metal source does not contain Co (NO)3)2·6H2O, addition of only 0.015mol of Mn (NO)3)2·6H2O、0.02molAl(NO3)3·9H2O, other parameters and conditions were exactly the same as those in example 1.
And (3) performance testing:
the residual alkali content in the positive electrode materials obtained in example 1 and comparative examples 1 to 4 was measured, and the results of the measurement are shown in table 1;
the capacity and cycle performance of the positive electrode materials obtained in the examples and comparative examples were tested;
the test conditions were: and (3) making the buckle electric: using the positive electrode materials prepared in the above-described examples 1, 2, 3, 1 and 2, respectively, positive electrode materials, carbon black conductive agents, binders PVDF and NMP (N-methylpyrrolidone) in a mass ratio of 95:2.5:2.5:5 were uniformly mixed to prepare battery positive electrode slurry. Coating the slurry on an aluminum foil with the thickness of 20-25 um, performing vacuum drying and rolling to prepare a positive electrode plate, taking a lithium metal plate as a negative electrode, dissolving 1.5mol of lithium hexafluorophosphate (LiPF6) in 1L of a mixed solvent of Ethylene Carbonate (EC) and dimethyl carbonate (DMC) to obtain an electrolyte, wherein the volume ratio of EC to DMC in the mixed solvent is 1:1, and assembling the button cell.
The electrical property test of the anode material adopts a blue battery test system to test at 25 ℃, and the test voltage range is 3V-4.5V; the first charge-discharge specific capacity and 50-cycle capacity retention rate were tested. The test results are shown in Table 2.
TABLE 1
| Li2CO3(％) | LiOH(％) | Total alkali (%) | |
| Example 1 | 0.08 | 0.14 | 0.22 |
| Comparative example 1 | 0.57 | 0.53 | 1.1 |
| Comparative example 2 | 0.41 | 0.25 | 0.66 |
| Comparative example 3 | 0.40 | 0.24 | 0.64 |
| Comparative example 4 | 0.42 | 0.23 | 0.65 |
As can be seen from table 1 above, the cobalt source, the aluminum source and the manganese source are used as raw materials and coated on the surface of the positive electrode material by the sol-gel method, so that the residual alkali content on the surface of the obtained coated positive electrode material is obviously reduced, thereby facilitating the preparation and use of the subsequent electrode slurry and improving the battery performance.
As can be seen from comparative example 1 and comparative examples 1 to 4, the coating metal sources include a cobalt source, a manganese source and an aluminum source, and the three metal sources form Mn (Al) in the subsequent sol-gel processmCon)2O8Which reacts with residual alkali on the surface of the positive electrode material to produce Li2Mn(AlmCon)2O9Thereby reducing the residual alkali on the surface of the anode material.
TABLE 2
According to the invention, a cobalt source, an aluminum source and a manganese source are used as raw materials, and are coated on the surface of a positive electrode material by a sol-gel method to form a coating layer on the surface of the positive electrode material, wherein the coating layer has electronic conductivity, and meanwhile, the contact area of the positive electrode material and an electrolyte can be reduced, side reactions are reduced, the cycle performance is improved, and the service life of a battery is prolonged; as can be seen from table 2 above, the first effect and the cycle retention rate of the coated cathode material of the present invention are both significantly improved;
comparing examples 1-3 with comparative examples 1-4, it can be seen that the invention employs cobalt source, manganese source and aluminum source as the coating metal source, which is beneficial for obtaining a coating layer with good electronic conductivity, and simultaneously effectively reduces the contact area between the anode material and the electrolyte, reduces the side reaction, and improves the first effect and the cycle retention rate.
As can be seen from comparison of examples 1 and 4-5, when the calcination temperature is within the range of 400-600 ℃, the obtained coated positive electrode material has better first-effect and cycle retention rate.
As can be seen from comparative examples 1, 6 to 9, the complexing solution contains EDTA-NH3When the molar ratio of water is (0.025-0.065) to (0.8-1.05) to (5-7), the obtained coated positive electrode material has better first effect and cycle retention rate, and when the composition ratio of the complexing solution does not meet the range, the first effect and cycle performance of the obtained coated positive electrode material are reduced.
The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.
Claims (24)
1. A preparation method of a coated cathode material is characterized by comprising the following steps:
adding the coating metal source into the complexing solution, mixing and heating to obtain gel; and
adding a positive electrode material into the gel, mixing and calcining to obtain the coated positive electrode material;
wherein the cladding metal source comprises a cobalt source, a manganese source and an aluminum source;
the complexing solution contains EDTA and NH3And water;
NH3adsorbing metal ions in the metal source with EDTA to form a metal ion complexThe complex and residual alkali on the surface of the anode material are subjected to chemical reaction to generate lithium manganese aluminum cobaltate;
the ratio of the molar weight of the cobalt source to the volume of the complexing solution is 0.15-0.35 mol/L;
the ratio of the molar weight of the manganese source to the volume of the complexing solution is 0.03-0.06 mol/L;
the ratio of the molar weight of the aluminum source to the volume of the complexing solution is 0.005-0.15 mol/L.
2. The production method according to claim 1, wherein the positive electrode material has a chemical formula of LixNiaCobMncAldMyO2Wherein x is more than or equal to 1.00 and less than or equal to 1.50, y is more than or equal to 0 and less than or equal to 0.02, a is more than or equal to 0 and less than or equal to 0.90, b is more than or equal to 0 and less than or equal to 0.06, c is more than or equal to 0 and less than or equal to 0.03, d is more than or equal to 0 and less than or equal to 0.03, and a + b + c + d is equal to 1; m comprises at least one of Y, Sr, Mo, La, Zr, Ti, Mg, B, Nb, Ba, Si, P and W.
3. The method of claim 1, wherein the heating temperature is 60 to 80 ℃.
4. The method of claim 1, wherein the heating is for a time of 5 to 6 hours.
5. The method of claim 1, wherein after adding the positive electrode material to the gel, after the mixing and before the calcining further comprises drying.
6. The method of claim 5, wherein the drying is vacuum drying.
7. The method according to claim 5, wherein the drying temperature is 150 ℃ to 200 ℃.
8. The method according to claim 5, wherein the drying time is 15 hours or more.
9. The method according to claim 1, wherein the temperature of the calcination is 400-600 ℃.
10. The method of claim 1, wherein the calcination is carried out for a time of 0.5 to 1 hour.
11. The method of claim 1, wherein the atmosphere of the calcination is an oxygen atmosphere.
12. The method according to claim 1, wherein the method for preparing the positive electrode material comprises:
and mixing the precursor with a lithium source, and sintering to obtain the cathode material.
13. The method of claim 12, wherein the precursor has a chemical formula of NiaCobMncAldMy(OH)2Wherein x is more than or equal to 1.00 and less than or equal to 1.50, y is more than or equal to 0 and less than or equal to 0.02, a is more than or equal to 0 and less than or equal to 0.90, b is more than or equal to 0 and less than or equal to 0.06, c is more than or equal to 0 and less than or equal to 0.03, d is more than or equal to 0 and less than or equal to 0.03, and a + b + c + d is equal to 1; m comprises at least one of Y, Sr, Mo, La, Zr, Ti, Mg, B, Nb, Ba, Si, P and W.
14. The method of claim 13, wherein the lithium source is selected from lithium hydroxide.
15. The method of claim 12, wherein the precursor is mixed with the lithium source by dry mixing.
16. The method of claim 12, wherein the molar ratio of the precursor to the lithium source is from 1:1 to 1: 1.50.
17. The method as claimed in claim 12, wherein the sintering temperature is 700-900 ℃.
18. The method of claim 12, wherein the sintering time is 8-15 hours.
19. The method according to claim 12, wherein an atmosphere for the sintering is an oxygen atmosphere.
20. The method according to claim 12, wherein the sintering further comprises cooling, pulverizing, and sieving to obtain a positive electrode material.
21. The method of claim 1, comprising:
dry mixing the precursor and lithium hydroxide according to the molar weight ratio of 1:1-1:1.50, sintering at the temperature of 700-900 ℃ in an oxygen atmosphere for 8-15h, cooling, crushing and sieving to obtain a positive electrode material; and
according to the molar ratio of EDTA to NH3Preparing a complex solution by water according to the proportion of (0.025-0.065) to (0.8-1.05) to (5-7); and
adding a cobalt source, a manganese source and an aluminum source into the complexing solution, stirring to form a red solution, and stirring and heating at 60-80 ℃ for 5-6 hours to obtain dark red gel; and
adding the anode material into dark red gel, uniformly stirring, then placing the gel in a vacuum drying box with the temperature of 150-.
22. The coated cathode material prepared by the preparation method according to any one of claims 1 to 21, wherein the coated cathode material comprises a cathode material and a coating layer on the surface of the cathode material.
23. The coated positive electrode material as defined in claim 22, wherein the ratio of the molar amounts of cobalt, manganese and aluminum in the coating layer is (15-35): (3-6): (0.5-15).
24. A battery comprising the encapsulated positive electrode material of claim 22.
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| WO2004097964A2 (en) * | 2003-04-24 | 2004-11-11 | The University Of Chicago | Lithium metal oxide electrodes for lithium batteries |
| CN108832093A (en) * | 2018-06-12 | 2018-11-16 | 桑德集团有限公司 | A kind of composite positive pole, preparation method and lithium ion battery |
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