WO2023024584A1 - Nickel-doped cobalt carbonate, and preparation method therefor and use thereof - Google Patents

Abstract

Disclosed in the present invention are nickel-doped cobalt carbonate, and a preparation method therefor and the use thereof. The method comprises: mixing a first carbonate solution and a nickel salt solution to react same, and controlling the temperature and pH to obtain a nickel carbonate seed crystal, wherein the first carbonate is one or two of sodium carbonate or potassium carbonate; mixing the nickel carbonate seed crystal, a cobalt salt solution and an ammonium bicarbonate solution to react same, and controlling the temperature and pH to obtain a nickel-doped cobalt carbonate slurry; and subjecting the nickel-doped cobalt carbonate slurry to solid-liquid separation, and washing and drying same to obtain nickel-doped cobalt carbonate. According to the present invention, a spherical nickel carbonate seed crystal is first prepared by using a nickel salt and sodium carbonate, a cobalt salt and ammonium bicarbonate are then added thereto to prepare cobalt carbonate, and nickel-doped cobalt carbonate is finally obtained; and after the nickel-doped cobalt carbonate is subjected to thermal decomposition, internal nickel can migrate outwards so as to obtain a cobaltosic oxide precursor material with nickel being uniformly distributed therein.

Description

Nickel-doped cobalt carbonate and its preparation method and application technical field

The invention belongs to the technical field of precursors of positive electrode materials for lithium-ion batteries, and in particular relates to a nickel-doped cobalt carbonate and its preparation method and application.

Background technique

Lithium cobaltate cathode material is mainly used in the 3C field due to its high energy density. With the popularization of 5G mobile phones, the requirements for lithium-ion battery life and volume continue to increase. Tricobalt tetroxide is used as the precursor of lithium cobaltate cathode material. It is prepared by thermal decomposition of cobalt carbonate. Doping nickel in the cobalt carbonate precursor is beneficial to improve the discharge specific capacity of high-voltage materials (4.45V and above); since the solubility product of nickel carbonate is much larger than that of cobalt carbonate, In the process of synthesizing nickel-doped cobalt carbonate by co-precipitation method, due to the low precipitation rate of nickel in the medium, the nickel content in the supernatant is high, which increases the cost of wastewater treatment and is difficult to realize industrial production.

Contents of the invention

The present invention aims to solve at least one of the technical problems in the above-mentioned prior art. Therefore, the present invention proposes a nickel-doped cobalt carbonate and its preparation method and application.

According to one aspect of the present invention, a kind of preparation method of nickel-doped cobalt carbonate is proposed, comprising the following steps:

S1: Mix the first carbonate solution and the nickel salt solution for reaction, and control the temperature and pH to obtain nickel carbonate seeds, and the first carbonate is one or both of sodium carbonate or potassium carbonate;

S2: Mix nickel carbonate seed crystals, cobalt salt solution and ammonium bicarbonate solution for reaction, and control temperature and pH to obtain nickel-doped cobalt carbonate slurry;

S3: subjecting the nickel-doped cobalt carbonate slurry to solid-liquid separation, washing and drying to obtain the nickel-doped cobalt carbonate.

In some embodiments of the present invention, the specific process of step S1 is: first add the second carbonate solution as the bottom liquid, and simultaneously add the first carbonate solution and the nickel salt solution to the bottom liquid The reaction is carried out, and the temperature and pH are controlled to obtain nickel carbonate seed crystals; the second carbonate is one or both of sodium carbonate and potassium carbonate.

In some embodiments of the present invention, in step S1, the concentration of the bottom liquid is 0.5-1.5 mol/L; preferably, the pH of the bottom liquid is 8.5-9.5.

In some embodiments of the present invention, in step S1, the temperature of the reaction is 38-42° C., and the pH is 8.0-9.0.

In some preferred embodiments of the present invention, the more specific process of step S1 is: first add the second carbonate solution to the reactor as the bottom liquid, control the temperature at 38-42°C, and add Nickel salt solution and sodium carbonate solution, the pH of the reaction is maintained at 8.0-9.0 by controlling the flow of the sodium carbonate solution, and when the particle size grows to the target value, the nickel carbonate seed crystals are obtained. The particle size of nickel carbonate seeds can be controlled by different pH of the bottom solution, the temperature and time of seed crystal synthesis, and then the content of nickel element in the finished sample can be controlled.

In some embodiments of the present invention, in step S1, the nickel salt is one or both of nickel chloride or nickel sulfate.

In some embodiments of the present invention, in step S1, the concentration of nickel ions in the nickel salt solution is 1.5-2.0 mol/L, and the concentration of the first carbonate solution is 1.5-2.5 mol/L. Preferably, the flow rate of the nickel salt solution is 2-3L/h, and the co-current time is 10-20h.

In some embodiments of the present invention, in step S2, the cobalt salt is one or both of cobalt chloride or cobalt sulfate.

In some embodiments of the present invention, in step S2, the temperature of the reaction is 45-55° C., and the pH is 7.0-7.5.

In some embodiments of the present invention, the specific process of step S2 is: add cobalt salt solution and ammonium bicarbonate solution in parallel to the reactor containing nickel carbonate seeds, control the temperature at 45-55°C, and control the temperature by controlling the hydrogen carbonate The flow rate of the ammonium solution maintains the pH of the reaction at 7.0-7.5. When the liquid level in the kettle reaches a certain height, the concentration is started. The cobalt salt solution and ammonium bicarbonate solution are continuously fed in and the liquid level in the kettle is kept relatively stable until the particle size grows to the target. value, namely the described nickel-doped cobalt carbonate slurry. The synthesis of nickel carbonate seed crystals and the growth of cobalt carbonate can be completed in the same reactor, and the reaction temperature is low, the energy consumption is low, and the synthesis efficiency is improved through the concentration process.

In some embodiments of the present invention, in step S1, the particle size D50 of the nickel carbonate seed crystal is 2-5 μm, and in step S3, the particle size D50 of the nickel-doped cobalt carbonate is 8-20 μm. Further, the mass fraction of nickel in the nickel-doped cobalt carbonate is 0.1-2%.

In some embodiments of the present invention, in step S2, the concentration of cobalt ions in the cobalt salt solution is 1.6-2.4mol/L, and the concentration of the ammonium bicarbonate solution is 2.0-3.0mol/L; preferably, The flow rate of the cobalt salt solution is 2-3L/h.

In some embodiments of the present invention, in step S3, the washing is performed with hot pure water at 70-80°C for 10-30 minutes; preferably, the drying temperature is 100-110°C. Further, the moisture content of the dried material is lower than 1%.

In some embodiments of the present invention, in step S3, sieving is performed after drying, and the mesh size of the sieve is 300-400.

The invention also provides a nickel-doped cobalt carbonate prepared by the preparation method.

The present invention also provides tricobalt tetroxide, which is prepared by thermal decomposition of the nickel-doped cobalt carbonate. The thermal decomposition temperature is 600-800° C. and the time is 3-5 hours.

According to a preferred embodiment of the present invention, it has at least the following beneficial effects:

1, the present invention uses nickel salt and sodium carbonate to prepare spherical nickel carbonate crystal seed earlier, then adds cobalt salt and ammonium bicarbonate and prepares cobalt carbonate, finally obtained nickel-doped cobalt carbonate, and its advantage is: (1) avoids in carbonic acid During the co-precipitation of nickel and cobalt in the acid salt system, because the solubility product of nickel carbonate is much greater than that of cobalt carbonate, the precipitation of nickel is not complete, resulting in the loss of nickel in the supernatant; (2) sodium carbonate is used as the Precipitant, because sodium carbonate is a strong base and weak acid salt, it provides CO for the reaction ₃ ^2- at the same time, it can also ensure that the system has a higher pH value, which is conducive to the uniform nucleation of nickel carbonate particles and the complete precipitation of nickel; (3 ) In the seed crystal growth stage, cobalt salt and ammonium bicarbonate are used as precipitants to ensure that the reaction proceeds smoothly, so that cobalt carbonate particles grow uniformly outward along the surface of the nickel carbonate crystal nucleus.

2. The nickel-doped cobalt carbonate of the present invention can make the internal nickel element migrate outward after thermal decomposition, and obtain a precursor material of tricobalt tetroxide with uniform distribution of nickel element.

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing and embodiment, wherein:

Fig. 1 is the SEM figure of 10000 times of nickel-doped cobalt carbonate of the embodiment of the present invention;

Fig. 2 is the SEM picture of 20,000 times of nickel-doped cobalt carbonate in Example 1 of the present invention;

Fig. 3 is the SEM picture of 10000 times of nickel-doped cobalt carbonate of embodiment 2 of the present invention;

Fig. 4 is the SEM picture of 20,000 times of nickel-doped cobalt carbonate in Example 2 of the present invention;

Fig. 5 is the SEM picture of 50,000 times of nickel-doped cobalt carbonate in Example 3 of the present invention;

Fig. 6 is the SEM picture of 10000 times of nickel-doped cobalt carbonate of embodiment 3 of the present invention;

Fig. 7 is the SEM picture of 50,000 times of nickel-doped cobalt carbonate in Example 4 of the present invention;

Fig. 8 is the SEM picture of 10,000 times of nickel-doped cobalt carbonate in Example 4 of the present invention;

Fig. 9 is the SEM figure of comparative example 1 cobalt carbonate 10000 times of the present invention;

Figure 10 is a cross-sectional view of nickel-doped cobalt tetroxide in Example 1 of the present invention;

Fig. 11 is a cross-sectional view of nickel-doped cobalt tetroxide in Example 2 of the present invention.

Detailed ways

The conception and technical effects of the present invention will be clearly and completely described below in conjunction with the embodiments, so as to fully understand the purpose, features and effects of the present invention. Apparently, the described embodiments are only some of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative efforts belong to The protection scope of the present invention.

Example 1

The present embodiment has prepared a kind of nickel-doped cobalt carbonate, and concrete process is:

Step 1. Preparation of solutions: 2.4 mol/L cobalt sulfate solution, 2.0 mol/L nickel sulfate solution, 3 mol/L ammonium bicarbonate solution, and 2.5 mol/L sodium carbonate solution were respectively prepared.

Step 2, nickel-doped cobalt carbonate synthesis

(1) Preparation of spherical nickel carbonate seed crystals: add pure water and sodium carbonate solution as the bottom liquid in the reaction kettle, the concentration of sodium carbonate in the bottom liquid is 0.5mol/L, the volume of the bottom liquid is based on submerging the bottom layer and stirring, the pH of the bottom liquid The value is 8.5, the temperature is 42°C, under the condition of high-speed stirring, add nickel sulfate solution and sodium carbonate solution concurrently, the flow rate of nickel sulfate solution is 3L/h, adjust the flow rate of sodium carbonate solution through the PLC control system to maintain the pH of the seed crystal synthesis stage The value is 8.0, co-flow for 20h, when the particle size grows to 5μm, stop feeding, and obtain spherical nickel carbonate seeds.

(2) Seed crystal growth: the reaction temperature is raised to 55°C, and cobalt sulfate solution and ammonium bicarbonate solution are added in flow, wherein the flow rate of cobalt sulfate solution is 3L/h, and the flow rate of ammonium bicarbonate solution is regulated and maintained by the PLC control system to maintain the seed crystal In the growth stage, the pH is 7.0, when the liquid level in the kettle reaches 70-80% of the total volume, the concentration is started, and the cobalt sulfate solution and ammonium bicarbonate solution are continuously introduced and the liquid level in the kettle is kept stable at 70-80% of the total volume until the particle size grows to 18.5 μm to obtain a nickel-doped cobalt carbonate slurry.

Step 3. Washing, drying, and screening of nickel-doped cobalt carbonate: put the slurry in the reaction kettle into a centrifuge for filtration, wash with 80°C hot pure water for 30 minutes, take the filter cake and dry it at 100°C until the moisture content is 0.3%. , passed through a 300-mesh vibrating sieve, and packed to obtain a nickel-doped cobalt carbonate finished product. The particle size D50 of the nickel-doped cobalt carbonate finished product is 18.5 μm, and the mass fraction of nickel element is 1%.

Figures 1 and 2 are SEM images of 10,000 times and 20,000 times the nickel-doped cobalt carbonate prepared in this example, respectively. From the figures, it can be seen that the surface of the particles is piled up in the form of powder particles without fine powder.

The nickel-doped cobalt carbonate prepared in this example was finally fired into a lithium cobalt oxide positive electrode material, and the metal lithium sheet was used as the negative electrode. The charge and discharge test of the button battery was carried out. When the charge and discharge voltage range was 3.0-4.55V, at a rate of 0.1C The first discharge specific capacity is 213.2mAg/g, and the capacity retention rate after 50 cycles at 0.5C rate is 94.6%.

Example 2

The present embodiment has prepared a kind of nickel-doped cobalt carbonate, and concrete process is:

Step 1. Preparation of solutions: 2.0 mol/L cobalt chloride solution, 1.8 mol/L nickel sulfate solution, 2.6 mol/L ammonium bicarbonate solution, and 2.0 mol/L sodium carbonate solution were respectively prepared.

Step 2, nickel-doped cobalt carbonate synthesis

(1) Preparation of spherical nickel carbonate seed crystals: add pure water and sodium carbonate solution as the bottom liquid in the reaction kettle, the concentration of sodium carbonate in the bottom liquid is 0.8mol/L, the volume of the bottom liquid is based on submerging the bottom layer and stirring, the pH of the bottom liquid The value is 8.8, the temperature is 42°C, under the condition of high-speed stirring, nickel sulfate solution and sodium carbonate solution are added in parallel, the flow rate of nickel sulfate solution is 2.6L/h, and the flow rate of sodium carbonate solution is adjusted through the PLC control system to maintain the seed crystal synthesis stage The pH value was 8.4, and flowed in parallel for 18 hours. When the particle size grew to 4 μm, the feeding was stopped to obtain spherical nickel carbonate seeds.

(2) Seed crystal growth: the reaction temperature was raised to 50° C., and cobalt chloride solution and ammonium bicarbonate solution were added, wherein the flow rate of cobalt chloride solution was 2.8 L/h. The flow rate of ammonium bicarbonate solution is adjusted by the PLC control system and the pH of the seed crystal growth stage is maintained at 7.2. When the liquid level in the kettle reaches 70-80% of the total volume, the concentration is started, and the cobalt chloride solution and ammonium bicarbonate solution are continuously fed and kept in the kettle. The internal liquid level stabilizes at 70-80% of the total volume. Until the particle size grows to 16.3 μm, a nickel-doped cobalt carbonate slurry is obtained.

Step 3. Washing, drying, and screening of nickel-doped cobalt carbonate: put the slurry in the reaction kettle into a centrifuge for filtration, wash with 80°C hot pure water for 30 minutes, take the filter cake and dry it at 105°C until the moisture content is 0.24%. , pass through a 350-mesh vibrating sieve, and get the nickel-doped cobalt carbonate finished product after packaging. The particle size D50 of the nickel-doped cobalt carbonate finished product is 16.3 μm, and the mass fraction of nickel element is 0.8%.

Figures 3 and 4 are SEM images of 20,000 times and 10,000 times the nickel-doped cobalt carbonate prepared in this example, respectively. It can be seen from the figures that the surface of the particles is piled up in the form of powder, without fine powder.

The nickel-doped cobalt carbonate prepared in this example was finally fired into a lithium cobalt oxide positive electrode material, and the metal lithium sheet was used as the negative electrode. The charge and discharge test of the button battery was carried out. When the charge and discharge voltage range was 3.0-4.55V, at a rate of 0.1C The first discharge specific capacity is 212.8mAg/g, and the capacity retention rate after 50 cycles at 0.5C rate is 93.7%.

Example 3

The present embodiment has prepared a kind of nickel-doped cobalt carbonate, and concrete process is:

Step 1. Preparation of solutions: 1.8 mol/L cobalt sulfate solution, 1.6 mol/L nickel chloride solution, 2.2 mol/L ammonium bicarbonate solution, and 1.8 mol/L sodium carbonate solution were respectively prepared.

Step 2, nickel-doped cobalt carbonate synthesis

(1) Spherical nickel carbonate seed crystal preparation: add pure water and sodium carbonate solution as the bottom liquid in the reaction kettle, the concentration of sodium carbonate in the bottom liquid is 1.0mol/L, the volume of the bottom liquid is based on submerging the bottom layer and stirring, the pH of the bottom liquid The value is 9.0, the temperature is 40°C, under the condition of high-speed stirring, nickel chloride solution and sodium carbonate solution are added in parallel, the flow rate of nickel chloride solution is 2.4L/h, and the flow rate of sodium carbonate solution is adjusted through the PLC control system to maintain the seed crystal In the synthesis stage, the pH value was 8.6, and the co-flow was 14 hours. When the particle size grew to 3 μm, the feeding was stopped to obtain spherical nickel carbonate seeds.

(2) Seed crystal growth: the reaction temperature is raised to 48°C, and cobalt sulfate solution and ammonium bicarbonate solution are added, wherein the cobalt sulfate solution flow rate is 2.4L/h, and the ammonium bicarbonate solution flow rate is regulated and maintained by the PLC control system. The pH of the seed growth stage was 7.4. When the liquid level in the kettle reaches 70-80% of the total volume, the concentration is started, and the cobalt sulfate solution and the ammonium bicarbonate solution are continuously introduced to keep the liquid level in the kettle stable at 70-80% of the total volume until the particle size grows to 12 μm to obtain nickel-doped Cobalt Carbonate Slurry.

Step 3. Washing, drying, and screening of nickel-doped cobalt carbonate: put the slurry in the reaction kettle into a centrifuge for filtration, wash with hot pure water at 75°C for 20 minutes, take the filter cake and dry it at 110°C until the moisture content is 0.58% , pass through a 400-mesh vibrating sieve, and get the nickel-doped cobalt carbonate finished product after packaging. The particle size D50 of the nickel-doped cobalt carbonate finished product is 12 μm, and the mass fraction of nickel element is 0.5%.

Figures 5 and 6 are SEM images of 50,000 times and 10,000 times the nickel-doped cobalt carbonate prepared in this example, respectively. It can be seen from the figures that the surface of the particles is piled up in blocks without fine powder.

Example 4

The present embodiment has prepared a kind of nickel-doped cobalt carbonate, and concrete process is:

Step 1. Preparation of solutions: 1.6 mol/L cobalt chloride solution, 1.5 mol/L nickel chloride solution, 2.0 mol/L ammonium bicarbonate solution, and 1.5 mol/L sodium carbonate solution were respectively prepared.

Step 2, nickel-doped cobalt carbonate synthesis

(1) Spherical nickel carbonate seed crystal preparation: add pure water and sodium carbonate solution as the bottom liquid in the reaction kettle, the sodium carbonate concentration of the bottom liquid is 1.5mol/L, the volume of the bottom liquid is based on submerging the bottom layer and stirring, the pH of the bottom liquid The value is 9.5, the temperature is 38°C, under the condition of high-speed stirring, nickel chloride solution and sodium carbonate solution are added in parallel, the flow rate of nickel chloride solution is 2.0L/h, and the flow rate of sodium carbonate solution is adjusted through the PLC control system to maintain the seed crystal In the synthesis stage, the pH value is 8.8, and the co-flow is 10 hours. When the particle size grows to 2 μm, the feeding is stopped to obtain spherical nickel carbonate seeds.

(2) Seed crystal growth: the reaction temperature was raised to 48° C., and cobalt chloride solution and ammonium bicarbonate solution were added, wherein the flow rate of cobalt chloride solution was 2.0 L/h. The flow rate of ammonium bicarbonate solution is adjusted by the PLC control system and maintains the pH of the seed crystal growth stage at 7.5. When the liquid level in the kettle reaches 70-80% of the total volume, the concentration is started, and the cobalt chloride solution and ammonium bicarbonate solution are continuously fed and kept in the kettle. The internal liquid level is stabilized at 70-80% of the total volume until the particle size grows to 8 μm to obtain a nickel-doped cobalt carbonate slurry.

Step 3. Washing, drying, and screening of nickel-doped cobalt carbonate: put the slurry in the reaction kettle into a centrifuge for filtration, wash with hot pure water at 75°C for 20 minutes, take the filter cake and dry it at 110°C until the moisture content is 0.84% , pass through a 400-mesh vibrating sieve, and get the nickel-doped cobalt carbonate finished product after packaging. The particle size D50 of the nickel-doped cobalt carbonate product is 8 μm, and the mass fraction of nickel element is 1.2%.

Figures 7 and 8 are SEM images of 50,000 times and 10,000 times the nickel-doped cobalt carbonate prepared in this example, respectively. It can be seen from the figures that the SEM shows that the surface of the particles is piled up in blocks without fine powder.

Comparative example 1

This comparative example has prepared a kind of cobalt carbonate, and the seed crystal prepared by this comparative example is cobalt carbonate crystal seed, and concrete process is:

Step 1. Preparation of solutions: prepare 2.0 mol/L cobalt chloride solution and 3 mol/L ammonium bicarbonate solution respectively.

Step 2, cobalt carbonate seed crystal synthesis

(1) Preparation of cobalt carbonate seed crystals: add pure water and ammonium bicarbonate solution into the reaction kettle as the bottom liquid, the concentration of the bottom liquid ammonium bicarbonate solution is 0.6mol/L, the volume of the bottom liquid is subject to submerging the bottom layer and stirring, the bottom liquid The pH value of the solution is 8.3, the temperature is 45°C, under the condition of high-speed stirring, cobalt chloride solution and ammonium bicarbonate solution are added in parallel, the flow rate of cobalt chloride solution is 3L/h, and the flow rate of ammonium bicarbonate solution is adjusted by the PLC control system The pH value of the seed crystal synthesis stage was maintained at 7.3. When the particle size grows to 5 μm, the feeding is stopped to obtain cobalt carbonate seed crystals.

(2) Cobalt carbonate seed crystal growth: the reaction temperature is raised to 55°C, and cobalt chloride solution and ammonium bicarbonate solution are added in flow, wherein the cobalt chloride solution flow rate is 3L/h, and the ammonium bicarbonate solution flow rate is regulated by the PLC control system And maintain the pH of the seed crystal growth stage at 7.0, when the liquid level in the kettle reaches 70-80% of the total volume, the concentration is started, the cobalt chloride solution and the ammonium bicarbonate solution are continuously fed and the liquid level in the kettle is kept stable at 70-80% of the total volume %. Until the particle size grows to 18.5 μm, cobalt carbonate slurry is obtained.

Step 3, cobalt carbonate washing, drying, and sieving: filter the slurry in the reaction kettle to a centrifuge, wash with 80°C hot pure water for 30 minutes, take the filter cake and dry it at 100°C to a moisture content of 0.2%, and pass 400-mesh vibrating sieve, and the cobalt carbonate finished product is obtained after packaging. The particle size D50 of the finished cobalt carbonate is 18.4 μm.

Fig. 9 is the SEM picture of 10000 times of the cobalt carbonate prepared in this comparative example, it can be seen from the picture that the surface of the particles is fine block accumulation.

The cobalt carbonate prepared in this comparative example is finally fired into a lithium cobalt oxide positive electrode material, and the metal lithium sheet is used as the negative electrode. The charge and discharge test of the button battery is carried out. When the charge and discharge voltage range is 3.0-4.55V, the first discharge is performed at a rate of 0.1C The specific capacity is only 199.1mAg/g, and the capacity retention rate is 86.5% after 50 cycles at a rate of 0.5C.

Test case

The finished products prepared in Example 1-2 and Comparative Example 1 were calcined at 680°C for 4 hours to obtain tricobalt tetroxide, which was then made into a lithium cobalt oxide positive electrode material, and the metal lithium sheet was used as the negative electrode. The charge and discharge test of the button battery was carried out. The charge and discharge voltage range It is 3.0-4.55V, and its electrochemical performance is shown in Table 1. The first discharge specific capacity at 0.1C rate is 213.2mAh/g, and the capacity retention rate after 50 cycles at 0.5C rate is 94.6%.

The electrochemical performance of table 1 embodiment 1-2 and comparative example 1

the case 0.1C first discharge specific capacity (mAh/g) 0.5C cycle capacity retention rate for 50 weeks (%) Example 1 213.2 94.6 Example 2 212.8 93.7 Comparative example 1 199.1 86.5

It can be seen from Table 1 that after nickel-doped cobalt carbonate is finally prepared into lithium cobaltate material, it has a higher specific capacity and better cycle performance under high voltage.

Figure 10 is a cross-sectional view of nickel-doped cobalt tetroxide in Example 1. The five rectangular areas of the cross-section were scanned by EDS, and the corresponding test results are shown in Table 2. The results show that the nickel element is uniformly distributed inside the particles.

Table 2

spectrogram Co (wt%) O (wt%) Ni (wt%) 1 73.50 25.58 0.92 2 70.76 28.09 1.15 3 70.69 28.28 1.03 4 71.82 27.1 1.08 5 72.54 26.51 0.95

Figure 11 is a cross-sectional view of nickel-doped cobalt tetroxide in Example 2. The five rectangular areas of the cross-section were scanned by EDS, and the corresponding test results are shown in Table 3. The results show that the nickel element is uniformly distributed inside the particles.

table 3

spectrogram Co (wt%) O (wt%) Ni (wt%) 1 72.1 27.07 0.83 2 71.53 27.71 0.76

3 70.69 28.41 0.90 4 74.21 24.98 0.81 5 72.68 26.47 0.85

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-mentioned embodiments, and within the scope of knowledge of those of ordinary skill in the art, various modifications can be made without departing from the spirit of the present invention. Variety. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other if there is no conflict.

Claims (10)

A kind of preparation method of nickel-doped cobalt carbonate, is characterized in that, comprises the following steps: S1: Mix the first carbonate solution and the nickel salt solution for reaction, and control the temperature and pH to obtain nickel carbonate seeds, and the first carbonate is one or both of sodium carbonate or potassium carbonate; S2: Mix nickel carbonate seed crystals, cobalt salt solution and ammonium bicarbonate solution for reaction, and control temperature and pH to obtain nickel-doped cobalt carbonate slurry; S3: subjecting the nickel-doped cobalt carbonate slurry to solid-liquid separation, washing and drying to obtain the nickel-doped cobalt carbonate. The preparation method according to claim 1, characterized in that, the specific process of step S1 is: first add the second carbonate solution as the bottom liquid, and simultaneously add the first carbonate solution and the bottom liquid to the bottom liquid. The nickel salt solution is reacted, and the temperature and pH are controlled to obtain nickel carbonate seeds; the second carbonate is one or both of sodium carbonate and potassium carbonate. The preparation method according to claim 1, characterized in that, in step S1, the temperature of the reaction is 38-42° C., and the pH is 8.0-9.0. The preparation method according to claim 2, characterized in that, in step S1, the concentration of the bottom liquid is 0.5-1.5 mol/L; preferably, the pH value of the bottom liquid is 8.5-9.5. The preparation method according to claim 2, characterized in that, in step S1, the concentration of nickel ions in the nickel salt solution is 1.5-2.0 mol/L, and the concentration of the first carbonate solution is 1.5-2.5 mol/L. The preparation method according to claim 1, characterized in that, in step S2, the temperature of the reaction is 45-55° C., and the pH is 7.0-7.5. The preparation method according to claim 1, wherein, in step S1, the particle diameter D50 of the nickel carbonate seed crystal is 2-5 μm, and in the step S3, the particle diameter D50 of the nickel-doped cobalt carbonate is 8-5 μm. 20 μm. The preparation method according to claim 1, characterized in that, in step S2, the concentration of cobalt ions in the cobalt salt solution is 1.6-2.4mol/L, and the concentration of the ammonium bicarbonate solution is 2.0-3.0mol/L L. A nickel-doped cobalt carbonate, characterized in that it is prepared by the preparation method described in any one of claims 1-8. A kind of tricobalt tetroxide is characterized in that, is made through pyrolysis by the nickel-doped cobalt carbonate described in claim 9.

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