High-tungsten-doped cobalt hydroxide and preparation method and application thereof

Abstract

The invention relates to high-tungsten-doped cobalt hydroxide and a preparation method and application thereof, and the preparation method comprises the following steps: mixing a complexing agent solution of cobalt salt and a precipitant solution of tungsten salt under the condition of a rotating speed of more than 600rpm, carrying out solid-liquid separation, and washing and drying to obtain the high-tungsten-doped cobalt hydroxide, in the complexing agent solution of the cobalt salt, a complexing agent comprises disodium ethylene diamine tetraacetate and / or citric acid; the dosage of the precipitant solution of the tungsten salt is such that the tungsten content in the highly tungsten-doped cobalt hydroxide reaches 2.5 wt% or above. According to the preparation method provided by the invention, rapid preparation of highly tungsten-doped cobalt hydroxide can be realized, and in addition, tungsten doping can be uniform by using the preparation method.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery materials, and relates to a cathode material, a preparation method and an application thereof, in particular to a highly tungsten-doped cobalt hydroxide and a preparation method and an application thereof. Background Art

[0002] Cobalt hydroxide is an inorganic compound that is insoluble in water, hardly soluble in strong alkalis, soluble in acids and ammonium salt solutions, and has a wide range of uses in industrial production. For example, cobalt hydroxide can be used as a colorant for glass or enamel, providing it with a rose color or a light cyan color; cobalt hydroxide can be used as a desiccant in the paint industry to improve the drying rate of the paint; it can also be used in the chemical industry to manufacture cobalt salts or other cobalt compounds and can be used as a cobalt-containing catalyst; in addition, cobalt hydroxide can be used as a decomposer in the electrolytic production of hydrogen peroxide; or as a cathode material for lithium batteries. Doping metal elements in cobalt hydroxide helps to improve the performance of cobalt hydroxide.

[0003] CN114671470A discloses a preparation method and application of tungsten-doped cobalt tetroxide. In this preparation method, a tungsten-containing compound and a molybdenum-containing compound are dissolved in an alkali solution to obtain a mixed solution; the mixed solution, a cobalt salt solution and a complexing agent are added to the bottom liquid in parallel for reaction, and the obtained precipitate is calcined in an oxygen-containing atmosphere, and the calcined material is soaked in a sodium sulfide solution to obtain tungsten-doped cobalt tetroxide. However, in the synthesis process, 6 mol / L ammonia water is required as a complexing agent, and the wastewater and toxic waste generated need to be treated before being discharged; moreover, the required reaction time is relatively long, and tungsten doping can only be achieved with the participation of molybdenum elements.

[0004] CN110247029A discloses a preparation method of small-particle-size and high-doping-content niobium-tungsten-tantalum cobalt tetroxide, including solution preparation, niobium-tungsten-tantalum crystal nucleus preparation, synthesis reaction, aging, filtration, washing, drying and calcination. By realizing a high-concentration cobalt solution at the beginning stage of synthesis and reducing the concentration of the synthesized cobalt solution as the synthesis time increases, the number of cobalt hydroxide crystal nuclei generated at the beginning stage of the synthesis reaction is increased, and the growth rate of cobalt hydroxide is inhibited. However, it requires the use of ammonia water and hydrazine hydrate, and the doping amount of tungsten can only reach 0.3%, and it is also difficult to achieve uniform doping of tungsten.

[0005] Therefore, there is a need to provide a highly tungsten-doped cobalt hydroxide with simple preparation, no need for the use of ammonia water, capable of achieving uniform doping of tungsten and having a high doping amount, as well as a preparation method and an application thereof. Summary of the Invention

[0006] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a highly tungsten-doped cobalt hydroxide, its preparation method and application. The preparation method can realize the rapid preparation of highly tungsten-doped cobalt hydroxide, and can make the tungsten content above 2.5 wt%, and in addition, the wet method used can make the tungsten doping uniform.

[0007] To achieve the purpose of this invention, the following technical solutions are adopted:

[0008] In the first aspect, the present invention provides a preparation method of highly tungsten-doped cobalt hydroxide, which is characterized in that the preparation method includes the following steps:

[0009] Under the condition of a rotation speed above 600 rpm, mix the complexing agent solution of cobalt salt with the precipitating agent solution of tungsten salt, perform solid-liquid separation, and obtain the highly tungsten-doped cobalt hydroxide after washing and drying;

[0010] In the complexing agent solution of cobalt salt, the complexing agent includes disodium ethylenediaminetetraacetate and / or citric acid;

[0011] The dosage of the precipitating agent solution of tungsten salt is such that the tungsten content in the highly tungsten-doped cobalt hydroxide reaches above 2.5 wt%, and can reach up to 5.45 wt%.

[0012] When preparing cobalt tetroxide by tungsten doping in the prior art, cobalt tetroxide and tungsten oxide are usually mechanically mixed by a dry method, resulting in uneven doping and a low doping amount of tungsten; when tungsten salt, precipitating agent and cobalt salt react, they are in a competitive relationship, and it is difficult to achieve high tungsten doping with a high precipitating agent dosage; while at a low precipitating agent dosage, although the tungsten content can be increased, the distribution is not uniform enough, the yield is low, and the cost is high. The preparation method provided by the present invention can achieve uniform high doping of tungsten when preparing cobalt hydroxide by a wet method; and then through conventional calcination, cobalt tetroxide with a high tungsten doping amount and uniform doping can be obtained.

[0013] Preferably, in the complexing agent solution of cobalt salt, the concentration of cobalt is 60 g / L - 120 g / L.

[0014] Preferably, in the complexing agent solution of cobalt salt, the concentration of the complexing agent is 0.8 g / L - 1.5 g / L.

[0015] Preferably, in the complexing agent solution of cobalt salt, the cobalt salt includes cobalt sulfate and / or cobalt chloride.

[0016] Preferably, in the precipitating agent solution of tungsten salt, the tungsten salt includes any one or a combination of at least two of sodium metatungstate, sodium tungstate, sodium paratungstate, ammonium metatungstate or ammonium tungstate.

[0017] Preferably, in the precipitating agent solution of tungsten salt, the precipitating agent includes sodium hydroxide.

[0018] Preferably, the volume ratio of the complexing agent solution of the cobalt salt to the precipitating agent solution of the tungstate is 15:1 - 32:1.

[0019] Preferably, the dosage of the precipitating agent solution of the tungstate is such that the alkali-cobalt ratio is 2.1 - 4.

[0020] In the present invention, the alkali-cobalt ratio refers to the molar ratio of the precipitating agent to cobalt in the cobalt salt.

[0021] Preferably, the mixing includes: within 3 minutes, uniformly adding the precipitating agent solution of the tungstate to the complexing agent solution of the cobalt salt.

[0022] Preferably, the mixing is carried out in a protective atmosphere.

[0023] Preferably, the temperature of the mixing is below 25°C.

[0024] Preferably, the drying method includes vacuum drying.

[0025] Preferably, the temperature of the vacuum drying is 70°C - 95°C.

[0026] In a second aspect, the present invention provides a highly tungsten-doped cobalt hydroxide, which is prepared by the preparation method described in the first aspect.

[0027] In a third aspect, the present invention provides an application of the highly tungsten-doped cobalt hydroxide described in the second aspect, and the highly tungsten-doped cobalt hydroxide is used for preparing a cathode material.

[0028] The numerical ranges described in the present invention not only include the specific point values exemplified above, but also include any point values between the above numerical ranges not exemplified. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the ranges.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] When preparing cobalt tetroxide by tungsten doping in the prior art, mechanical mixing of cobalt tetroxide and tungsten oxide is usually carried out by a dry method, resulting in uneven doping and a low tungsten doping amount; the present invention discovers that there is a competitive relationship when tungstate, precipitating agent and cobalt salt react. Although cobalt hydroxide can be obtained with a high precipitating agent dosage, it is difficult to achieve high tungsten doping; while at a low precipitating agent dosage, although the tungsten content can be increased, the distribution is not uniform enough, the yield is low, and the cost is high; the preparation method provided by the present invention can achieve uniform high doping of tungsten when preparing cobalt hydroxide by a wet method; and then through conventional calcination, cobalt tetroxide with a high content and uniform distribution of doped tungsten can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1SEM image of highly tungsten-doped cobalt hydroxide obtained in Example 1 of the present invention;

[0032] Figure 2 EDS point scan image of highly tungsten-doped cobalt hydroxide obtained in Example 1 of the present invention;

[0033] Figure 3 、 Figure 4 EDS area scan image of highly tungsten-doped cobalt hydroxide obtained in Example 1 of the present invention;

[0034] Figure 5 SEM image of highly tungsten-doped cobalt hydroxide obtained in Example 2 of the present invention;

[0035] Figure 6 EDS point scan image of highly tungsten-doped cobalt hydroxide obtained in Example 2 of the present invention;

[0036] Figure 7 、 Figure 8 EDS area scan image of highly tungsten-doped cobalt hydroxide obtained in Example 2 of the present invention;

[0037] Figure 9 SEM image of highly tungsten-doped cobalt hydroxide obtained in Example 3 of the present invention;

[0038] Figure 10 EDS point scan image of highly tungsten-doped cobalt hydroxide obtained in Example 3 of the present invention;

[0039] Figure 11 、 Figure 12 EDS area scan image of highly tungsten-doped cobalt hydroxide obtained in Example 3 of the present invention;

[0040] Figure 13 SEM image of highly tungsten-doped cobalt hydroxide obtained in Example 4 of the present invention;

[0041] Figure 14 EDS point scan image of tungsten-doped cobalt hydroxide obtained in Example 4 of the present invention;

[0042] Figure 15 SEM image of tungsten-doped cobalt hydroxide obtained in Example 5 of the present invention;

[0043] Figure 16 、 Figure 17 EDS area scan image of tungsten-doped cobalt hydroxide obtained in Example 5 of the present invention;

[0044] Figure 18 SEM image of tungsten-doped cobalt hydroxide obtained in Example 6 of the present invention;

[0045] Figure 19 、 Figure 20 EDS area scan image of tungsten-doped cobalt hydroxide obtained in Example 6 of the present invention;

[0046] Figure 21 SEM image of cobalt hydroxide doped with tungsten obtained in Example 7 of the present invention;

[0047] Figure 22 EDS point scan image of cobalt hydroxide doped with tungsten obtained in Example 7 of the present invention;

[0048] Figure 23 SEM image of cobalt hydroxide doped with tungsten obtained in Application Example 1 of the present invention;

[0049] Figure 24 EDS point scan image of cobalt hydroxide doped with tungsten obtained in Application Example 1 of the present invention. Detailed implementation manners

[0050] The technical solution of the present invention will be further described below through specific implementation manners. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0051] The present invention provides a method for preparing highly tungsten-doped cobalt hydroxide, characterized in that the preparation method comprises the following steps:

[0052] Under the condition of a rotation speed above 600 rpm, a complexing agent solution of cobalt salt is mixed with a precipitating agent solution of tungsten salt, and after solid-liquid separation, washing and drying, the highly tungsten-doped cobalt hydroxide is obtained;

[0053] In the complexing agent solution of cobalt salt, the complexing agent includes disodium ethylenediaminetetraacetate and / or citric acid;

[0054] The dosage of the precipitating agent solution of tungsten salt is such that the tungsten content in the highly tungsten-doped cobalt hydroxide reaches 2.5 wt% or more, and can reach up to 5.45 wt%.

[0055] When tungsten doping is carried out for the preparation of cobalt tetroxide in the prior art, cobalt tetroxide and tungsten oxide are usually mechanically mixed by a dry method, resulting in uneven doping and a low doping amount of tungsten; the preparation method provided by the present invention conducts tungsten doping during the preparation of cobalt hydroxide, which can achieve uniform doping of tungsten; and then through conventional calcination, cobalt tetroxide with uniform tungsten doping can be obtained, thereby realizing a high tungsten doping amount of cobalt tetroxide.

[0056] In some embodiments, in the complexing agent solution of cobalt salt, the concentration of cobalt is 60 g / L - 120 g / L, for example, it can be 60 g / L, 80 g / L, 90 g / L, 100 g / L or 120 g / L, but is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0057] In some embodiments, in the complexing agent solution of the cobalt salt, the concentration of the complexing agent is 0.8 g / L - 1.5 g / L. For example, it can be 0.8 g / L, 0.9 g / L, 1 g / L, 1.2 g / L, or 1.5 g / L, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0058] In some embodiments, in the complexing agent solution of the cobalt salt, the cobalt salt includes cobalt sulfate and / or cobalt chloride.

[0059] In some embodiments, in the precipitating agent solution of the tungsten salt, the tungsten salt includes any one or a combination of at least two of sodium metatungstate, sodium tungstate, sodium paratungstate, ammonium metatungstate, or ammonium tungstate. Typical but non-limiting combinations include the combination of sodium metatungstate and sodium tungstate, the combination of sodium metatungstate and sodium paratungstate, the combination of sodium metatungstate, sodium tungstate, and sodium paratungstate, the combination of ammonium metatungstate and ammonium tungstate, or the combination of sodium metatungstate, sodium tungstate, sodium paratungstate, ammonium metatungstate, and ammonium tungstate.

[0060] The complexing agent used in the preparation method provided by the present invention is not applicable to ammonia water, and there is no need to treat impurity ions such as ammonia nitrogen in the wastewater.

[0061] In some embodiments, in the precipitating agent solution of the tungsten salt, the precipitating agent includes sodium hydroxide.

[0062] In some embodiments, the volume ratio of the complexing agent solution of the cobalt salt to the precipitating agent solution of the tungsten salt is 15:1 - 32:1. For example, it can be 15:1, 18:1, 20:1, 24:1, 25:1, 28:1, 30:1, or 32:1, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0063] In some embodiments, the dosage of the precipitating agent solution of the tungsten salt is such that the alkali-cobalt ratio is 2.1 - 4. For example, it can be 2.1, 2.5, 2.8, 3, 3.2, 3.5, or 4, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0064] The alkali-cobalt ratio referred to in the present invention means the molar ratio of the precipitating agent to cobalt in the cobalt salt.

[0065] In some embodiments, the mixing includes: uniformly adding the precipitating agent solution of the tungsten salt to the complexing agent solution of the cobalt salt within 3 minutes.

[0066] In some embodiments, the mixing is carried out in a protective atmosphere.

[0067] The protective atmosphere described in the present invention includes any one or a combination of at least two of nitrogen, helium, neon, or argon. Typical but non-limiting combinations include a combination of nitrogen and helium, a combination of helium and neon, a combination of neon and argon, a combination of helium, neon, and argon, or a combination of nitrogen, helium, neon, and argon.

[0068] In certain embodiments, the temperature of the mixing is below 25°C. For example, it can be 20°C, 21°C, 22°C, 23°C, 24°C, or 25°C, but is not limited to the listed values. The remaining unlisted values within the numerical range are equally applicable.

[0069] The preparation method provided by the present invention has a low mixing temperature, can achieve a high doping amount of tungsten, and the doping of tungsten is uniform.

[0070] In certain embodiments, the drying method includes vacuum drying.

[0071] In certain embodiments, the temperature of the vacuum drying is 70°C - 95°C. For example, it can be 70°C, 75°C, 80°C, 85°C, 90°C, or 95°C, but is not limited to the listed values. The remaining unlisted values within the numerical range are equally applicable.

[0072] An embodiment of the present invention provides a cobalt hydroxide highly doped with tungsten, which is prepared by the preparation method described in any one of the embodiments.

[0073] An embodiment of the present invention provides an application of the cobalt hydroxide highly doped with tungsten described in any one of the embodiments, and the cobalt hydroxide highly doped with tungsten is used for preparing a cathode material.

[0074] Exemplarily, using the cobalt hydroxide highly doped with tungsten to prepare cobalt tetroxide includes: calcining the cobalt hydroxide highly doped with tungsten to obtain the cobalt tetroxide.

[0075] In certain embodiments, the temperature of the calcination includes 540°C - 560°C. For example, it can be 540°C, 545°C, 550°C, 555°C, or 560°C, but is not limited to the listed values. The remaining unlisted values within the numerical range are equally applicable.

[0076] In certain embodiments, the time of the calcination is 2h - 4h. For example, it can be 2h, 2.5h, 3h, 3.5h, or 4h, but is not limited to the listed values. The remaining unlisted values within the numerical range are equally applicable.

[0077] Example 1

[0078] This example provides a preparation method of a cobalt hydroxide highly doped with tungsten. The preparation method includes:

[0079] (1) In a nitrogen atmosphere, prepare 10 L of a complexing agent solution of cobalt salt;

[0080] In the complexing agent solution of cobalt salt, the cobalt salt is cobalt chloride and the complexing agent is EDTA-2Na;

[0081] In the complexing agent solution of cobalt salt, the concentration of cobalt is 60 g / L and the concentration of the complexing agent is 1 g / L;

[0082] (2) Add 1.98 L of a sodium hydroxide solution with a mass fraction of 32% (the alkali-cobalt ratio is 2.1) and 90.29 g of sodium tungstate dihydrate to 2 L of water, mix evenly to obtain a precipitating agent solution of tungsten salt;

[0083] (3) Under the condition of a nitrogen atmosphere, adjust the rotation speed to 600 rpm. At a temperature of 25 °C, add the precipitating agent solution of tungsten salt to the complexing agent solution of cobalt salt at a uniform speed within 3 min;

[0084] (4) Perform solid-liquid separation and vacuum dry at a temperature of 90 °C to obtain cobalt hydroxide doped with high tungsten content with a tungsten content of 5.34 wt%.

[0085] The SEM image of the cobalt hydroxide doped with high tungsten content obtained in this example is as Figure 1 shown, the EDS point scan image is as Figure 2 shown, and the ESD surface scan image is as Figure 3 、 Figure 4 shown.

[0086] It can be seen from Figures 1 - 4 that the cobalt hydroxide doped with high tungsten content obtained in this example has a smaller particle size, a higher tungsten content, and uniform doping.

[0087] Example 2

[0088] This example provides a preparation method of cobalt hydroxide doped with high tungsten content. The preparation method includes:

[0089] (1) In a nitrogen atmosphere, prepare 10 L of a complexing agent solution of cobalt salt;

[0090] In the complexing agent solution of cobalt salt, the cobalt salt is cobalt chloride and the complexing agent is EDTA-2Na;

[0091] In the complexing agent solution of cobalt salt, the concentration of cobalt is 60 g / L and the concentration of the complexing agent is 0.8 g / L;

[0092] (2) Add 3.77 L of a sodium hydroxide solution with a mass fraction of 32% (the alkali-cobalt ratio is 4) and 90.29 g of sodium tungstate dihydrate to 2 L of water, mix evenly to obtain a precipitating agent solution of tungsten salt;

[0093] (3) Under the condition of nitrogen atmosphere, adjust the rotation speed to 600 rpm. At a temperature of 25 °C, add the precipitant solution of tungsten salt to the complexing agent solution of cobalt salt uniformly within 3 min.

[0094] (4) Perform solid-liquid separation and vacuum dry at a temperature of 80 °C to obtain high-doped tungsten cobalt hydroxide with a tungsten content of 2.61 wt%.

[0095] The SEM image of the high-doped tungsten cobalt hydroxide obtained in this example is as shown in Figure 5 shown, and the EDS point scan image is as shown in Figure 6 shown, and the ESD surface scan images are as shown in Figure 7 、 Figure 8 shown.

[0096] It can be seen from Figures 5 - 8 that the high-doped tungsten cobalt hydroxide obtained in this example has more flakes, a lower tungsten content, and slightly uneven doping.

[0097] Example 3

[0098] This example provides a preparation method of high-doped tungsten cobalt hydroxide. The preparation method includes:

[0099] (1) In a nitrogen atmosphere, prepare 10 L of a complexing agent solution of cobalt salt;

[0100] In the complexing agent solution of cobalt salt, the cobalt salt is cobalt chloride and the complexing agent is EDTA-2Na;

[0101] In the complexing agent solution of cobalt salt, the concentration of cobalt is 120 g / L and the concentration of the complexing agent is 1.5 g / L;

[0102] (2) Add 3.96 L of sodium hydroxide solution with a mass fraction of 32% (the alkali-cobalt ratio is 2.1) and 180.59 g of sodium tungstate dihydrate to 2 L of water, and mix evenly to obtain the precipitant solution of tungsten salt;

[0103] (3) Under the condition of nitrogen atmosphere, adjust the rotation speed to 600 rpm. At a temperature of 25 °C, add the precipitant solution of tungsten salt to the complexing agent solution of cobalt salt uniformly within 3 min.

[0104] (4) Perform solid-liquid separation and vacuum dry at a temperature of 95 °C to obtain high-doped tungsten cobalt hydroxide with a tungsten content of 5.45 wt%.

[0105] The SEM image of the high-doped tungsten cobalt hydroxide obtained in this example is as shown in Figure 9 shown, and the EDS point scan image is as shown in Figure 10 shown, and the ESD surface scan images are as shown in Figure 11 、 Figure 12 shown.

[0106] It can be seen from Figures 9 - 12It can be seen that the high tungsten-doped cobalt hydroxide obtained in this example has a small particle size, good dispersion, a high tungsten content, and uniform doping.

[0107] Example 4

[0108] This example provides a preparation method for high tungsten-doped cobalt hydroxide, and the preparation method includes:

[0109] (1) In a nitrogen atmosphere, prepare a 10L complexing agent solution of cobalt salt;

[0110] In the complexing agent solution of cobalt salt, the cobalt salt is cobalt sulfate and the complexing agent is EDTA-2Na;

[0111] In the complexing agent solution of cobalt salt, the concentration of cobalt is 60g / L and the concentration of the complexing agent is 1.2g / L;

[0112] (2) Add 1.98L of sodium hydroxide solution with a mass fraction of 32% (the alkali-cobalt ratio is 2.1) and 69.80g of ammonium tungstate hexahydrate to 2L of water, mix evenly to obtain a precipitating agent solution of tungsten salt;

[0113] (3) Under the condition of a nitrogen atmosphere, adjust the rotation speed to 600rpm, and at a temperature of 25°C, add the precipitating agent solution of tungsten salt to the complexing agent solution of cobalt salt uniformly within 3 minutes;

[0114] (4) Perform solid-liquid separation and vacuum dry at a temperature of 95°C to obtain high tungsten-doped cobalt hydroxide with a tungsten content of 5.28wt%.

[0115] The SEM image of the high tungsten-doped cobalt hydroxide obtained in this example is as Figure 13 shown, and the EDS point scan image is as Figure 14 shown.

[0116] From Figure 13 , Figure 14 it can be seen that the high tungsten-doped cobalt hydroxide obtained in this example has a small particle size, a high tungsten content, and uniform doping.

[0117] Example 5

[0118] This example provides a preparation method for high tungsten-doped cobalt hydroxide, and the preparation method includes:

[0119] (1) In a nitrogen atmosphere, prepare a 10L complexing agent solution of cobalt salt;

[0120] In the complexing agent solution of cobalt salt, the cobalt salt is cobalt chloride and the complexing agent is EDTA-2Na;

[0121] In the complexing agent solution of cobalt salt, the concentration of cobalt is 60g / L and the concentration of the complexing agent is 1.2g / L;

[0122] (2) Add 5.66 L of sodium hydroxide solution with a mass fraction of 32% (alkali-cobalt ratio is 6) and 90.29 g of sodium tungstate dihydrate to 2 L of water, mix evenly to obtain a precipitant solution of tungsten salt;

[0123] (3) Under the condition of nitrogen atmosphere, adjust the rotation speed to 600 rpm, and at a temperature of 25 °C, add the precipitant solution of tungsten salt to the complexing agent solution of cobalt salt at a constant speed within 3 min;

[0124] (4) Perform solid-liquid separation and vacuum dry at a temperature of 90 °C to obtain cobalt hydroxide doped with high tungsten content with a tungsten content of 1.32 wt%.

[0125] The SEM image of the cobalt hydroxide doped with high tungsten content obtained in this example is as shown in Figure 15 shown, and the ESD surface scan image is as shown in Figure 16 、 Figure 17 shown.

[0126] It can be seen from Figures 15 - 17 that due to the too high alkali-cobalt ratio, the cobalt hydroxide doped with high tungsten content obtained in this example has more flakes, larger particle size, poor dispersibility, and lower tungsten content.

[0127] Example 6

[0128] This example provides a preparation method of cobalt hydroxide doped with high tungsten content, and the preparation method includes:

[0129] (1) In an air atmosphere, prepare 10 L of a complexing agent solution of cobalt salt;

[0130] In the complexing agent solution of cobalt salt, the cobalt salt is cobalt chloride and the complexing agent is EDTA-2Na;

[0131] In the complexing agent solution of cobalt salt, the concentration of cobalt is 60 g / L and the concentration of the complexing agent is 1.2 g / L;

[0132] (2) Add 1.98 L of sodium hydroxide solution with a mass fraction of 32% (alkali-cobalt ratio is 2.1) and 90.29 g of sodium tungstate dihydrate to 2 L of water, mix evenly to obtain a precipitant solution of tungsten salt;

[0133] (3) Under the condition of air atmosphere, adjust the rotation speed to 600 rpm, and at a temperature of 25 °C, add the precipitant solution of tungsten salt to the complexing agent solution of cobalt salt at a constant speed within 3 min;

[0134] (4) Perform solid-liquid separation and vacuum dry at a temperature of 90 °C to obtain cobalt hydroxide doped with high tungsten content with a tungsten content of 2.74 wt%.

[0135] The SEM image of the cobalt hydroxide doped with high tungsten content obtained in this example is as shown in Figure 18 shown, and the ESD surface scan image is as shown in Figure 19 、Figure 20 as shown

[0136] From Figures 18 - 20 it can be seen that the high tungsten-doped cobalt hydroxide flakes obtained in this example are reduced compared with those in Example 5, the particle size is still large, the dispersibility is poor, and the tungsten doping amount is increased.

[0137] Example 7

[0138] This example provides a preparation method of high tungsten-doped cobalt hydroxide, and the preparation method includes:

[0139] (1) In a nitrogen atmosphere, prepare a 10L complexing agent solution of cobalt salt;

[0140] In the complexing agent solution of cobalt salt, the cobalt salt is cobalt chloride, and the complexing agent is EDTA-2Na;

[0141] In the complexing agent solution of cobalt salt, the concentration of cobalt is 60 g / L;

[0142] (2) Add 1.98 L of sodium hydroxide solution with a mass fraction of 32% (the alkali-cobalt ratio is 2.1) and 90.29 g of sodium tungstate dihydrate to 2 L of water, mix evenly to obtain a precipitating agent solution of tungsten salt;

[0143] (3) Under the condition of a nitrogen atmosphere, adjust the rotation speed to 600 rpm, and at a temperature of 40 °C, add the precipitating agent solution of tungsten salt to the complexing agent solution of cobalt salt uniformly within 3 min;

[0144] (4) Perform solid-liquid separation, and vacuum dry at a temperature of 90 °C to obtain high tungsten-doped cobalt hydroxide with a tungsten content of 2.24 wt%.

[0145] The SEM image of the high tungsten-doped cobalt hydroxide obtained in this example is as Figure 21 shown, and the ESD point scan image is as Figure 22 shown.

[0146] From Figure 21 and Figure 22 it can be seen that due to the increase in the mixing temperature, the flakes of the high tungsten-doped cobalt hydroxide obtained in this example increase and the tungsten content decreases.

[0147] Comparative Example 1

[0148] This comparative example provides a preparation method of high tungsten-doped cobalt hydroxide, and the preparation method includes:

[0149] (1) In a nitrogen atmosphere, prepare a 10L cobalt salt solution;

[0150] In the cobalt salt solution, the cobalt salt is cobalt chloride;

[0151] In the cobalt salt solution, the concentration of cobalt is 60 g / L;

[0152] (2) Add 1.98 L of sodium hydroxide solution with a mass fraction of 32% (alkali-cobalt ratio is 2.1) and 90.29 g of sodium tungstate dihydrate to 2 L of water, mix evenly to obtain a precipitant solution of tungsten salt.

[0153] (3) Under the condition of nitrogen atmosphere, adjust the rotation speed to 600 rpm, and at a temperature of 25 °C, slowly add the precipitant solution of tungsten salt to the cobalt salt solution evenly within 3 min.

[0154] (4) Perform solid-liquid separation and vacuum dry at a temperature of 90 °C to obtain cobalt hydroxide doped with high content of tungsten with a tungsten content of 1.75 wt%.

[0155] Performance Characterization

[0156] Calcine the cobalt hydroxide obtained in the above examples and comparative examples at 550 °C for 3 h to obtain cobalt tetroxide. Among them, the tungsten content in the cobalt tetroxide obtained by calcining the cobalt hydroxide doped with high content of tungsten in Example 3 reaches 6.20%. Its SEM image is as shown in Figure 23 shown, and the EDS point scan image is as shown in Figure 24 shown. It can be seen from Figure 23 and Figure 24 that the tungsten content in the sample after calcination is significantly increased, the particle size is small, the dispersion is good, and the tungsten is evenly dispersed.

[0157] Mix cobalt tetroxide with lithium carbonate, control the molar ratio of Li to Co to be 1.06:1, and then perform solid-phase sintering at a temperature of 1000 °C for 12 h to obtain a lithium cobalt oxide cathode material.

[0158] Mix the lithium cobalt oxide cathode material, acetylene black and PVDF in a molar ratio of 92:4:4 and add them to NMP to obtain a positive electrode slurry. Then coat the positive electrode slurry on an aluminum foil to obtain a positive electrode sheet; use a lithium sheet as the negative electrode sheet and make a CR2430 button battery in a glove box filled with argon. Conduct electrical performance tests in a blue battery test system, where:

[0159] In the measurement of particle size by laser particle size method, the consistency (also called uniformity) refers to the degree of dispersion of the particle size distribution in the sample, that is, the degree to which the particle size deviates from the average value. This parameter reflects the concentration or dispersion of the particle population, similar to the standard deviation concept in statistics. The smaller the value, the closer the particle size is to the average value and the more uniform the particle size distribution is;

[0160] The test conditions for specific capacity are charging and discharging at a rate of 0.5C at room temperature, charging cut-off voltage is 4.3V, and discharging cut-off voltage is 3.0V;

[0161] The test conditions for the first-cycle capacity retention rate are the same as those for the specific capacity test method, which is the first-cycle discharge capacity / charging capacity.

[0162] Table 1

[0163]

[0164]

[0165] In summary, when preparing cobalt tetroxide by doping tungsten in the prior art, cobalt tetroxide and tungsten oxide are usually mechanically mixed by a dry method, resulting in uneven doping and a low doping amount of tungsten; when tungsten salt, precipitant and cobalt salt react, they are in a competitive relationship. Although cobalt hydroxide can be obtained with a high precipitant dosage, it is difficult to achieve high tungsten doping; while at a low precipitant dosage, although the tungsten content can be increased, the distribution is not uniform enough, the yield is low, and the cost is high. The preparation method provided by the present invention dopes tungsten when preparing cobalt hydroxide, and can achieve uniform high doping of tungsten; then through conventional calcination, cobalt tetroxide with uniform tungsten doping can be obtained, thereby realizing high tungsten doping amount in cobalt tetroxide with small particle size.

[0166] The applicant declares that the above description is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by any person skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A preparation method of high tungsten-doped cobalt hydroxide, characterized in that, The preparation method comprises the following steps: Under the condition of a rotation speed above 600 rpm, a complexing agent solution of cobalt salt is mixed with a precipitating agent solution of tungsten salt, followed by solid-liquid separation, washing and drying to obtain the high tungsten-doped cobalt hydroxide; In the complexing agent solution of cobalt salt, the complexing agent includes disodium ethylenediaminetetraacetate and / or citric acid; The dosage of the precipitating agent solution of tungsten salt is such that the tungsten content in the high tungsten-doped cobalt hydroxide reaches 2.5 wt% or more.

2. The preparation method according to claim 1, characterized in that, In the complexing agent solution of cobalt salt, the concentration of cobalt is 60 g / L - 120 g / L; Preferably, in the complexing agent solution of cobalt salt, the concentration of the complexing agent is 0.8 g / L - 1.5 g / L.

3. The preparation method according to claim 1 or 2, characterized in that, In the complexing agent solution of cobalt salt, the cobalt salt includes cobalt sulfate and / or cobalt chloride.

4. The preparation method according to any one of claims 1 to 3, characterized in that, In the precipitating agent solution of tungsten salt, the tungsten salt includes any one or a combination of at least two of sodium metatungstate, sodium tungstate, sodium paratungstate, ammonium metatungstate or ammonium tungstate; Preferably, in the precipitating agent solution of tungsten salt, the precipitating agent includes sodium hydroxide.

5. The preparation method according to any one of claims 1-4, characterized in that, The volume ratio of the complexing agent solution of cobalt salt to the precipitating agent solution of tungsten salt is 15:1 - 32:1; Preferably, the dosage of the precipitating agent solution of tungsten salt is such that the alkali-cobalt ratio is 2.1 - 4.

6. The preparation method according to any one of claims 1-5, characterized in that, The mixing includes: within 3 minutes, the precipitating agent solution of tungsten salt is uniformly added to the complexing agent solution of cobalt salt.

7. The preparation method according to any one of claims 1-6, characterized in that, The mixing is carried out in a protective atmosphere; Preferably, the temperature of the mixing is below 25°C.

8. The preparation method according to any one of claims 1-7, characterized in that, The drying method includes vacuum drying; Preferably, the temperature of the vacuum drying is 70°C - 95°C.

9. A high tungsten-doped cobalt hydroxide, characterized in that, The high tungsten-doped cobalt hydroxide is prepared by the preparation method according to any one of claims 1 - 8.

10. Use of the cobalt hydroxide highly doped with tungsten according to claim 9, characterized in that, The high tungsten-doped cobalt hydroxide is used for preparing a cathode material.

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