Preparation method and application of cobalt oxyhydroxide

Abstract

The present invention discloses a preparation method and application of cobalt oxyhydroxide, comprising the following steps: S1: Prepare a cobalt solution and an ammonium bicarbonate solution; S2: Use part of the ammonium bicarbonate solution as the bottom liquid, add the cobalt solution and the ammonium bicarbonate solution to the bottom liquid, and collect the first seed crystal after the reaction; S3: Add the cobalt solution and the ammonium bicarbonate solution to the first seed crystal, collect the second seed crystal after the reaction, repeat the collection of the seed crystal and then add the cobalt solution and the ammonium bicarbonate solution until the D50 of the obtained seed crystal is 17-18 μm; S4: After collecting the seed crystal with a D50 of 17-18 μm, add the cobalt solution and the ammonium bicarbonate solution to react; In the bottom liquid of step S2, the preparation method of cobalt oxyhydroxide of the present invention can shorten the reaction cycle and avoid small particles appearing during the reaction process.

Description

Technical Field

[0001] The present invention relates to the technical field of battery material preparation, and particularly relates to a preparation method and application of cobalt oxyhydroxide. Background Art

[0002] Lithium-ion batteries are widely used because of their high energy density, long cycle life, high working voltage, strong safety, and small self-discharge effect. At present, improving the performance of lithium batteries mainly includes: improving the cycle performance and increasing the energy density of the battery. In terms of the cycle life of lithium batteries, the focus is mainly on the stability of the electrode-electrolyte interface. The electrodes and electrolytes of lithium batteries are in direct contact. During the operation of the battery, redox reactions occur between the electrodes and electrolytes of lithium batteries, which will corrode the electrodes of lithium batteries, reduce the electrode-electrolyte stability, and cause capacity attenuation of lithium batteries. Coating a thin layer between the electrode and the electrolyte can effectively solve the corrosion of the electrode by the electrolyte, thereby improving the cycle life of lithium batteries. Existing coating materials such as cobalt hydroxide and cobalt oxyhydroxide have a specific surface area between 15 - 25 m 2 / g, with a relatively small specific surface area and poor coating performance.

[0003] Therefore, there is an urgent need to develop a method to improve the coating performance of coating materials. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. For this purpose, the present invention provides a preparation method of cobalt oxyhydroxide, which can improve the coating performance of coating materials.

[0005] According to a first aspect embodiment of the present invention, a preparation method of cobalt oxyhydroxide includes mixing and reacting a cobalt solution, an alkali solution, and an oxidant;

[0006] The alkali solution includes ammonia water;

[0007] The oxidant includes hydrogen peroxide;

[0008] Calculated by molar ratio, the hydrogen peroxide and the ammonia water are 0.11:0.88 - 0.3:0.7.

[0009] The principle of the present invention is as follows: Ammonia water plays a complexing role in the reaction. When Co 2+ is less (as shown in Equation Ⅰ), a precipitate is directly formed; when Co 2+ is in excess, the precipitate that appears at the beginning of the reaction will dissolve, and then a flocculent or surface granular precipitate will be formed (as shown in Equation Ⅱ). Hydrogen peroxide enters the reaction kettle along with the cobalt solution and decomposes into O 2+, simultaneously oxidizing the cobalt ammonia complex to convert it into flocculent cobalt oxyhydroxide; as the amount of hydrogen peroxide increases, the degree of oxidation becomes better, and more of its flocculent structure is retained, resulting in a larger specific surface area. The present invention realizes the control of the specific surface area of cobalt oxyhydroxide by adjusting the amounts of ammonia water and hydrogen peroxide, and the process is simple and easy to operate. Using this method to prepare cobalt oxyhydroxide, the specific surface area can be regulated to meet the market's requirements for the specific surface area of coating materials.

[0010] Co 2+ +2NH3·H2O=Co(OH)2↓+NH 4+ (Equation Ⅰ)

[0011] Co 2+ +6NH3·H2O={Co(NH3)6}2++6H2O (Equation Ⅱ)

[0012] According to some embodiments of the present invention, the method for preparing cobalt oxyhydroxide includes:

[0013] S1. Mixing a cobalt solution and an oxidant to obtain solution A;

[0014] S2. Adding solution A to the ammonia water solution with adjusted pH value and mixing them to react to obtain a cobalt oxyhydroxide slurry.

[0015] According to some embodiments of the present invention, in step S2, it includes adding solution A to the ammonia water solution with adjusted pH value using a peristaltic pump.

[0016] According to some embodiments of the present invention, the flow rate of the compressed air in the peristaltic pump is 5-7 L / min.

[0017] According to some embodiments of the present invention, the alkali solution further includes at least one of potassium hydroxide aqueous solution, sodium hydroxide aqueous solution, and lithium hydroxide aqueous solution.

[0018] According to some embodiments of the present invention, in the cobalt solution, the concentration of cobalt ions is 1.5-2.5 mol / L.

[0019] According to some embodiments of the present invention, the concentration of the ammonia water is 5%-25%.

[0020] According to some embodiments of the present invention, the concentration of hydrogen peroxide is 5%-35%.

[0021] According to some embodiments of the present invention, the temperature of the mixing reaction is 30-80 °C.

[0022] According to some embodiments of the present invention, the time of the mixing reaction is 2-4 h.

[0023] According to some embodiments of the present invention, after the reaction, it further includes washing and drying.

[0024] According to some embodiments of the present invention, the washing includes washing the sodium content of the cobalt oxyhydroxide slurry to not higher than 500 ppm.

[0025] According to some embodiments of the present invention, cooling is further included after the drying.

[0026] According to some embodiments of the present invention, the temperature of the drying is 70 - 120 °C, and the time of the drying is 10 - 15 h.

[0027] According to some embodiments of the present invention, the cobalt solution includes at least one of an aqueous cobalt chloride solution, an aqueous cobalt sulfate solution, and an aqueous cobalt nitrate solution.

[0028] According to some embodiments of the present invention, the concentration of the cobalt solution is 70 - 160 g / L.

[0029] According to some embodiments of the present invention, the reaction includes a stirring reaction.

[0030] According to some embodiments of the present invention, the rotation speed of the stirring reaction is 600 - 800 r / min.

[0031] According to an embodiment of the first aspect of the present invention, an electrode, the preparation raw materials of the electrode include cobalt oxyhydroxide prepared by the described preparation method.

[0032] Other features and advantages of the present invention will be set forth in the following description, and in part will be obvious from the description, or can be learned by practicing the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, wherein:

[0034] Figure 1 is a scanning electron microscope (SEM) picture of the product obtained in Example 1;

[0035] Figure 2 is a scanning electron microscope (SEM) picture of the product obtained in Example 1;

[0036] Figure 3 is a scanning electron microscope (SEM) picture of the product obtained in Example 1 after drying and crushing;

[0037] Figure 4 is a scanning electron microscope (SEM) picture of the product obtained in Example 1 after drying and crushing. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the present invention and should not be construed as limiting the present invention.

[0039] Example 1

[0040] This example discloses a preparation method of cobalt oxyhydroxide, and its process includes the following steps:

[0041] S1: Weigh 1816 g of cobalt chloride, add pure water, make up the volume to 4 L, filter to remove solid impurities, and obtain a clean cobalt chloride solution;

[0042] S2: Measure 30 ml of hydrogen peroxide and add it to the cobalt chloride solution, and mix evenly to obtain a mixed solution B;

[0043] S3: Measure 1140 ml of ammonia water solution and add it to 2000 ml of sodium hydroxide solution, and mix evenly to obtain a mixed solution A;

[0044] S4: Use a peristaltic pump to pump the mixed solution A into the reaction kettle within 10 min as the bottom liquid; set the rotation speed at 600 r / min, the temperature at 60 °C, and the compressed air flow rate at 5 L / min;

[0045] S5: At 60 °C, use a peristaltic pump to pump the mixed solution B into the reaction kettle in step S4 within 30 min, and keep it warm for 2 h to obtain a cobalt oxyhydroxide slurry;

[0046] S6: Wash the sodium content of the cobalt oxyhydroxide slurry to below 500 ppm, then press the slurry dry and put it into a drying oven, keep it warm at 100 °C for 12 h, and then cool and detect the dried material.

[0047] Figure 1 SEM picture of the product obtained in Example 1;

[0048] Figure 2 SEM picture of the product obtained in Example 1;

[0049] Figure 3 SEM picture of the dried and crushed product obtained in Example 1;

[0050] Figure 4 SEM picture of the dried and crushed product obtained in Example 1.

[0051] Example 2

[0052] This example discloses a preparation method of cobalt oxyhydroxide, and its process includes the following steps:

[0053] S1: Weigh 1816 g of cobalt chloride, add pure water, make up the volume to 4 L, filter to remove solid impurities, and obtain a clean cobalt chloride solution;

[0054] S2: Measure 30 ml of hydrogen peroxide solution and add it to the cobalt chloride solution, mix evenly to obtain mixture B;

[0055] S3: Measure 1140 ml of ammonia water solution and add it to 2000 ml of sodium hydroxide solution, mix evenly to obtain mixture A;

[0056] S4: Use a peristaltic pump to pump mixture A into the reaction kettle within 10 min as the bottom liquid; set the rotation speed at 600 r / min, the temperature at 60 °C, and the compressed air flow rate at 5 L / min;

[0057] S5: At 60 °C, use a peristaltic pump to pump mixture B into the reaction kettle in step S4 within 30 min, keep it warm for 2 h, and obtain cobalt oxyhydroxide slurry;

[0058] S6: Wash the sodium content of the cobalt oxyhydroxide slurry to less than 500 ppm, press the slurry dry, put it into a drying oven, keep it warm at 100 °C for 12 h, and obtain the dried material for cooling and testing.

[0059] Example 3

[0060] This example discloses a preparation method of cobalt oxyhydroxide, and its process comprises the following steps:

[0061] S1: Weigh 1816 g of cobalt chloride, add pure water, make up the volume to 4 L, filter to remove solid impurities, and obtain a clean cobalt chloride solution;

[0062] S2: Measure 30 ml of hydrogen peroxide solution and add it to the cobalt chloride solution, mix evenly to obtain mixture B;

[0063] S3: Measure 1140 ml of ammonia water solution and add it to 2000 ml of sodium hydroxide solution, mix evenly to obtain mixture A;

[0064] S4: Use a peristaltic pump to pump mixture A into the reaction kettle within 10 min as the bottom liquid; set the rotation speed at 600 r / min, the temperature at 60 °C, and the compressed air flow rate at 5 L / min;

[0065] S5: At 60 °C, use a peristaltic pump to pump mixture B into the reaction kettle in step S4 within 30 min, keep it warm for 2 h, and obtain cobalt oxyhydroxide slurry;

[0066] S6: Wash the sodium content of the cobalt oxyhydroxide slurry to less than 500 ppm, press the slurry dry, put it into a drying oven, keep it warm at 100 °C for 12 h, and obtain the dried material for cooling and testing.

[0067] Example 5

[0068] This example discloses a preparation method of cobalt oxyhydroxide, and its process includes the following steps:

[0069] S1: Weigh 1816 g of cobalt chloride, add pure water, make up the volume to 4 L, filter to remove solid impurities, and obtain a clean cobalt chloride solution;

[0070] S2: Measure 30 ml of hydrogen peroxide solution and add it to the cobalt chloride solution, and mix evenly to obtain mixture B;

[0071] S3: Measure 1140 ml of ammonia water solution and add it to 2000 ml of sodium hydroxide solution, and mix evenly to obtain mixture A;

[0072] S4: Use a peristaltic pump to pump mixture A into the reaction kettle within 10 min as the bottom liquid; set the rotation speed at 600 r / min, the temperature at 60 °C, and the compressed air flow rate at 5 L / min;

[0073] S5: At 60 °C, use a peristaltic pump to pump mixture B into the reaction kettle in step S4 within 30 min, keep warm for 2 h, and obtain cobalt oxyhydroxide slurry;

[0074] S6: Wash the sodium content of the cobalt oxyhydroxide slurry to below 500 ppm, press the slurry dry and put it into a drying oven, keep warm at 100 °C for 12 h, and obtain the dried material for cooling and detection.

[0075] Example 6

[0076] This example discloses a preparation method of cobalt oxyhydroxide. The difference between this example and Example 1 is that the added amount of hydrogen peroxide in step S2 is 35 ml, and the rest of the process is the same.

[0077] Example 7

[0078] This example discloses a preparation method of cobalt oxyhydroxide. The difference between this example and Example 2 is that the added amount of hydrogen peroxide in step S2 is 35 ml, and the rest of the process is the same.

[0079] Example 8

[0080] This example discloses a preparation method of cobalt oxyhydroxide. The difference between this example and Example 3 is that the added amount of hydrogen peroxide in step S2 is 35 ml, and the rest of the process is the same.

[0081] Example 9

[0082] This embodiment discloses a preparation method of cobalt oxyhydroxide. The difference between this embodiment and Embodiment 4 is that the addition amount of hydrogen peroxide in step S2 is 35 ml, and the remaining processes are the same.

[0083] Embodiment 10

[0084] This embodiment discloses a preparation method of cobalt oxyhydroxide. The difference between this embodiment and Embodiment 5 is that the addition amount of hydrogen peroxide in step S2 is 35 ml, and the remaining processes are the same.

[0085] Embodiment 11

[0086] This embodiment discloses a preparation method of cobalt oxyhydroxide. The difference between this embodiment and Embodiment 1 is that the addition amount of hydrogen peroxide in step S2 is 40 ml, and the remaining processes are the same.

[0087] Embodiment 12

[0088] This embodiment discloses a preparation method of cobalt oxyhydroxide. The difference between this embodiment and Embodiment 2 is that the addition amount of hydrogen peroxide in step S2 is 40 ml, and the remaining processes are the same.

[0089] Embodiment 13

[0090] This embodiment discloses a preparation method of cobalt oxyhydroxide. The difference between this embodiment and Embodiment 3 is that the addition amount of hydrogen peroxide in step S2 is 40 ml, and the remaining processes are the same.

[0091] Embodiment 14

[0092] This embodiment discloses a preparation method of cobalt oxyhydroxide. The difference between this embodiment and Embodiment 4 is that the addition amount of hydrogen peroxide in step S2 is 40 ml, and the remaining processes are the same.

[0093] Embodiment 15

[0094] This embodiment discloses a preparation method of cobalt oxyhydroxide. The difference between this embodiment and Embodiment 5 is that the addition amount of hydrogen peroxide in step S2 is 40 ml, and the remaining processes are the same.

[0095] Test Example 1

[0096] In this test example, the physical and chemical indexes of the cobalt oxyhydroxide sample prepared in the above embodiment and its cross-section were detected by electron microscopy, and the results are shown in Table 1.

[0097] Table 1 Performance Test Results

[0098]

[0099] According to the records in Table 1, the cobalt oxyhydroxide coating material in the present invention has a large specific surface area, and its microscopic morphology presents a flocculent structure. When coating the same volume of materials with other coating materials such as cobalt hydroxide, the flocculent structure of cobalt oxyhydroxide has better coating uniformity than the flaky structure of cobalt hydroxide, and the specific surface area of cobalt oxyhydroxide is large, so the strength of coating the same material is good.

[0100] The embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art, various changes can be made without departing from the gist of the present invention.

Claims

1. A preparation method of cobalt oxyhydroxide, characterized in that, It includes the following steps: S1. Mix a cobalt solution and an oxidant to obtain solution A; S2. Add solution A to the ammonia water with adjusted pH value and mix and react to obtain a cobalt oxyhydroxide slurry; The oxidant is hydrogen peroxide; By molar ratio, the hydrogen peroxide and the ammonia water are 0.11:0.88 to 0.3:0.7; In the cobalt solution, the concentration of cobalt ions is 1.5 to 2.5 mol / L; The concentration of the ammonia water is 5% to 25%; The concentration of the hydrogen peroxide is 5% to 35%; The temperature of the mixing reaction is 30 to 80 °C; The time of the mixing reaction is 2 to 4 h.

2. The preparation method according to claim 1, wherein After the reaction ends, it also includes washing and drying.

3. The preparation method according to claim 2, characterized in that, The temperature of the drying is 100 to 120 °C, and the time of the drying is 2 to 3 h.

4. The preparation method according to claim 1, characterized in that The cobalt solution includes at least one of an aqueous cobalt chloride solution, an aqueous cobalt sulfate solution, and an aqueous cobalt nitrate solution.

5. The preparation method according to claim 4, characterized in that, The concentration of the cobalt solution is 70 - 160 g / L.

6. The preparation method according to claim 1, wherein, The reaction includes a stirring reaction, and the rotation speed of the stirring reaction is 600 to 800 r / min.

7. An electrode, characterized in that, The preparation raw material of the electrode includes cobalt oxyhydroxide prepared by the preparation method according to any one of claims 1 to 6.

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