Iron-magnesium-doped spherical precursor manganous-manganic oxide and preparation method thereof

Abstract

The invention belongs to the technical field of lithium ion battery positive electrode materials, and particularly relates to an iron-magnesium-doped spherical precursor manganous-manganic oxide and a preparation method thereof, the chemical formula of the iron-magnesium-doped spherical precursor manganous-manganic oxide is MnFexMgyO (8 / 3 + 3x + 2y) / 2, x is more than or equal to 0.001 and less than or equal to 0.005, and y is more than or equal to 0.0015 and less than or equal to 0.0065. The iron and magnesium doped spherical precursor manganous-manganic oxide is in a granular shape; the invention also discloses a preparation method of the ferrum and magnesium doped spherical precursor manganous-manganic oxide. The material has the advantages of high tap density, small specific surface area, low impurity content, high energy density, good cycle performance, good safety performance and excellent rate capability after being sintered into lithium manganate.

Description

Technical Field

[0001] The invention relates to the technical field of lithium ion battery positive electrode materials, in particular to an iron-magnesium-doped spherical precursor manganese manganese tetraoxide and a preparation method thereof. Background Art

[0002] The cathode material used in lithium batteries is mainly lithium cobalt oxide, which is expensive and toxic. Compared with traditional cathode materials such as lithium cobalt oxide, ternary materials, and lithium iron phosphate, lithium manganese oxide cathode materials have advantages such as good safety performance, superior cycle performance, and rate performance.

[0003] Lithium manganese oxide is a very important lithium battery positive electrode material product on the market. It is mainly produced by solid phase sintering method, and the production process is relatively mature. At present, many manufacturers mainly use manganese dioxide as the main raw material to produce lithium manganese oxide. In order to obtain qualified lithium manganese oxide products, the purchased manganese dioxide needs to be processed before it can be used in the production of lithium manganese oxide, which undoubtedly increases the production cost of lithium manganese oxide. In addition, electrolytic manganese dioxide itself has a high impurity content, and it is easy to bring in iron impurities due to mechanical equipment problems during the crushing process. These factors have a negative impact on the quality of lithium manganese oxide products. The prepared lithium manganese oxide is an amorphous particle with a large specific surface area. The produced lithium manganese oxide has the disadvantages of poor high temperature cycle performance and poor safety. Therefore, an iron-magnesium doped spherical precursor manganese tetraoxide and a preparation method thereof are invented. The spherical precursor manganese tetraoxide and lithium manganate have the same spinel structure. The production of lithium manganate using the spherical precursor manganese tetraoxide as a raw material can reduce the adverse effects caused by structural changes. Experiments show that the preparation of lithium manganate using the spherical precursor manganese tetraoxide as a raw material can significantly improve its electrochemical properties: enhance structural stability, improve high-temperature cycle performance, improve rate performance, improve capacity, etc., and can also improve raw material utilization, simplify production processes, and reduce production costs. Lithium manganate produced using high-density spherical manganese tetraoxide exhibits excellent electrochemical properties. Summary of the invention

[0004] In view of the above and / or existing problems in the existing iron-magnesium-doped spherical precursor manganese tetraoxide and its preparation method, the present invention is proposed.

[0005] Therefore, the purpose of the present invention is to provide an iron-magnesium-doped spherical precursor manganese tetraoxide and a preparation method thereof, which can solve the above-mentioned existing problems.

[0006] In order to improve the energy density and cycle performance of lithium manganate, according to one aspect of the present invention, the present invention provides the following technical solution:

[0007] An iron-doped magnesium-based spherical precursor manganese tetraoxide, wherein the chemical formula of the iron-doped magnesium-based spherical precursor manganese tetraoxide is: MnFex Mg y O (8 / 3+3x+2y) / 2 , where 0.001≤x≤0.005, 0.0015≤y≤0.0065.

[0008] As a preferred embodiment of the iron-doped magnesium-type spherical precursor trimanganese tetraoxide described in the present invention, the iron-doped magnesium-type spherical precursor trimanganese tetraoxide is in granular form.

[0009] As a preferred embodiment of the iron-doped magnesium-type spherical precursor manganese tetraoxide, the particle size distribution of the iron-doped magnesium-type spherical precursor manganese tetraoxide is: 50 =6.0~12.0μm, D 10 ≥4.0μm, D 90 ≤25μm.

[0010] A method for preparing an iron-magnesium-doped spherical precursor manganese tetraoxide comprises the following specific steps:

[0011] Step 1: preparing manganese sulfate, iron salt and magnesium salt in a certain proportion into a manganese sulfate mixed solution;

[0012] Step 2: Dilute ammonia water to 15% with pure water;

[0013] Step 3: Prepare sodium carbonate solution according to a certain ratio;

[0014] Step 4: adding manganese sulfate mixed solution, ammonia water and sodium carbonate into the reaction kettle in a certain proportion, and controlling the pH value;

[0015] Step 5: After the reaction is completed, solid powder will be obtained, and the solid powder will be centrifuged and washed;

[0016] Step 6: placing the washed solid powder in a muffle furnace for sintering while introducing nitrogen;

[0017] Step 7: Screen the sintered solid powder to obtain the iron-magnesium-doped spherical precursor manganese manganese tetraoxide.

[0018] As a preferred embodiment of the method for preparing the iron-magnesium-doped spherical precursor manganese manganese tetroxide according to the present invention, the molar ratio of Fe:Mn in step 1 is 0.001≤x≤0.005; the molar ratio of Mg:Mn is 0.0015≤y≤0.0065.

[0019] As a preferred embodiment of the method for preparing the iron-magnesium-doped spherical precursor manganese manganese tetroxide according to the present invention, the pH value in step 4 is controlled between 6.0 and 8.5.

[0020] As a preferred embodiment of the method for preparing the iron-magnesium-doped spherical precursor manganese manganese tetroxide described in the present invention, the sintering temperature in step six is ​​300-900° C. and the sintering time is 3-4 hours.

[0021] As a preferred embodiment of the method for preparing an iron-doped magnesium spherical precursor manganese tetraoxide according to the present invention, the nitrogen ventilation rate in step 6 is 0.4±0.2 cm 3 / h.

[0022] As a preferred embodiment of the method for preparing the iron-magnesium-doped spherical precursor manganese manganese tetroxide according to the present invention, the screen in step seven is a vibrating screen with a mesh size of 150-250.

[0023] Compared with existing technologies:

[0024] 1. The iron-doped magnesium-based spherical precursor manganese tetraoxide of the present invention has a narrow particle size distribution and a tap density of 2.7 g / cm3. After being used in lithium-ion batteries, it has a high volume energy density, a high voltage platform, good cycle performance, good safety performance, and superior rate performance;

[0025] 2. The preparation method of the present invention obtains spinel particles with a narrow particle size distribution by controlling the synthesis process of the reactor, and strictly controls the reaction temperature and reaction time, thereby avoiding the problem of large fluctuations in particle size and specific surface area, which leads to poor product performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is an electron microscope image of the iron-magnesium-doped spherical precursor manganese tetraoxide of the present invention;

[0027] Figure 2 It is a process flow chart of the present invention;

[0028] Figure 3 The graph is a particle size distribution curve of the iron-magnesium-doped spherical precursor manganese tetraoxide of the present invention. DETAILED DESCRIPTION

[0029] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0030] Embodiment 1:

[0031] The present invention provides a spherical precursor of iron-doped magnesium-manganese tetraoxide, please refer to Figure 1-Figure 3 The chemical formula of the iron-doped magnesium spherical precursor manganese tetraoxide is: MnFe x Mg y O (8 / 3+3x+2y) / 2 , where 0.001≤x≤0.005, 0.0015≤y≤0.0065.

[0032] The iron-magnesium-doped spherical precursor manganese manganese tetraoxide is in granular form.

[0033] A method for preparing an iron-magnesium-doped spherical precursor manganese tetraoxide comprises the following specific steps:

[0034] Step 1: Manganese sulfate, iron salt and magnesium salt are prepared into a manganese sulfate mixed solution in a certain proportion, wherein the molar ratio of Fe:Mn is 0.001; the molar ratio of Mg:Mn is 0.0015;

[0035] Step 2: Dilute ammonia water to 15% with pure water;

[0036] Step 3: Prepare sodium carbonate solution according to a certain ratio;

[0037] Step 4: adding manganese sulfate mixed solution, ammonia water and sodium carbonate into the reaction kettle in a certain proportion, and controlling the pH value, wherein the pH value is controlled between 6.0;

[0038] Step 5: After the reaction is completed, solid powder will be obtained, and the solid powder will be centrifuged and washed;

[0039] Step 6: Place the washed solid powder in a muffle furnace for sintering while introducing nitrogen. The sintering temperature is 300°C and the sintering time is 3h. The nitrogen ventilation rate is 0.4±0.2cm 3 / h;

[0040] Step 7: Screening the sintered solid powder to obtain the iron-magnesium-doped spherical precursor manganese manganese tetraoxide, wherein the screen is a 150-mesh vibrating screen.

[0041] The tap density of the iron-doped magnesium spherical precursor manganese tetraoxide prepared by this method is 2.71 g / cm 3 , the specific surface area is 0.35m2 / g, and its particle size distribution is: D 50 =8.64μm, D 10 =4.52μm, D 90 =15.38μm.

[0042] Embodiment 2:

[0043] The present invention provides a spherical precursor of iron-doped magnesium-manganese tetraoxide, please refer to Figure 1-Figure 3 The chemical formula of the iron-doped magnesium spherical precursor manganese tetraoxide is: MnFe x Mg y O (8 / 3+3x+2y) / 2 , where 0.001≤x≤0.005, 0.0015≤y≤0.0065.

[0044] The iron-magnesium-doped spherical precursor manganese manganese tetraoxide is in granular form.

[0045] A method for preparing an iron-magnesium-doped spherical precursor manganese tetraoxide comprises the following specific steps:

[0046] Step 1: Manganese sulfate, iron salt and magnesium salt are prepared into a manganese sulfate mixed solution in a certain proportion, wherein the molar ratio of Fe:Mn is 0.002; the molar ratio of Mg:Mn is 0.0025;

[0047] Step 2: Dilute ammonia water to 15% with pure water;

[0048] Step 3: Prepare sodium carbonate solution according to a certain ratio;

[0049] Step 4: adding manganese sulfate mixed solution, ammonia water and sodium carbonate into the reaction kettle in a certain proportion, and controlling the pH value, wherein the pH value is controlled between 6.5;

[0050] Step 5: After the reaction is completed, solid powder will be obtained, and the solid powder will be centrifuged and washed;

[0051] Step 6: Place the washed solid powder in a muffle furnace for sintering while introducing nitrogen. The sintering temperature is 400°C, the sintering time is 3.25h, and the nitrogen ventilation volume is 0.4±0.2cm 3 / h;

[0052] Step 7: Screening the sintered solid powder to obtain the iron-magnesium-doped spherical precursor manganese manganese tetraoxide, wherein the screen is a 175-mesh vibrating screen.

[0053] The tap density of the iron-doped magnesium spherical precursor manganese tetraoxide prepared by this method is 2.76 g / cm 3 , the specific surface area is 0.37m2 / g, and its particle size distribution is: D 50 =8.91μm, D 10 =4.61μm, D 90 =15.98μm.

[0054] Embodiment 3:

[0055] The present invention provides a spherical precursor of iron-doped magnesium-manganese tetraoxide, please refer to Figure 1-Figure 3 The chemical formula of the iron-doped magnesium spherical precursor manganese tetraoxide is: MnFe x Mg y O (8 / 3+3x+2y) / 2 , where 0.001≤x≤0.005, 0.0015≤y≤0.0065.

[0056] The iron-magnesium-doped spherical precursor manganese manganese tetraoxide is in granular form.

[0057] A method for preparing an iron-magnesium-doped spherical precursor manganese tetraoxide comprises the following specific steps:

[0058] Step 1: Manganese sulfate, iron salt and magnesium salt are prepared into a manganese sulfate mixed solution in a certain proportion, wherein the molar ratio of Fe:Mn is 0.003; the molar ratio of Mg:Mn is 0.0035;

[0059] Step 2: Dilute ammonia water to 15% with pure water;

[0060] Step 3: Prepare sodium carbonate solution according to a certain ratio;

[0061] Step 4: adding manganese sulfate mixed solution, ammonia water and sodium carbonate into the reaction kettle in a certain proportion, and controlling the pH value, wherein the pH value is controlled between 7;

[0062] Step 5: After the reaction is completed, solid powder will be obtained, and the solid powder will be centrifuged and washed;

[0063] Step 6: Place the washed solid powder in a muffle furnace for sintering while introducing nitrogen. The sintering temperature is 600°C and the sintering time is 3.5h. The nitrogen ventilation rate is 0.4±0.2cm 3 / h;

[0064] Step 7: Screening the sintered solid powder to obtain the iron-magnesium-doped spherical precursor manganese manganese tetraoxide, wherein the screen is a 200-mesh vibrating screen.

[0065] After testing, the iron- and magnesium-doped spherical power-type lithium manganate precursor prepared by this method, manganese tetraoxide, has a tap density of 2.87 g / cm 3 , the specific surface area is 0.41m2 / g, and its particle size distribution is: D 50 =9.27μm, D 10 =4.79μm, D 90 =16.41μm.

[0066] Embodiment 4:

[0067] The present invention provides a spherical precursor of iron-doped magnesium-manganese tetraoxide, please refer to Figure 1-Figure 3 The chemical formula of the iron-doped magnesium spherical precursor manganese tetraoxide is: MnFe x Mg y O (8 / 3+3x+2y) / 2 , where 0.001≤x≤0.005, 0.0015≤y≤0.0065.

[0068] The iron-magnesium-doped spherical precursor manganese manganese tetraoxide is in granular form.

[0069] A method for preparing an iron-magnesium-doped spherical precursor manganese tetraoxide comprises the following specific steps:

[0070] Step 1: Manganese sulfate, iron salt and magnesium salt are prepared into a manganese sulfate mixed solution in a certain proportion, wherein the molar ratio of Fe:Mn is 0.004; the molar ratio of Mg:Mn is 0.0045;

[0071] Step 2: Dilute ammonia water to 15% with pure water;

[0072] Step 3: Prepare sodium carbonate solution according to a certain ratio;

[0073] Step 4: adding manganese sulfate mixed solution, ammonia water and sodium carbonate into the reaction kettle in a certain proportion, and controlling the pH value, wherein the pH value is controlled between 7.5;

[0074] Step 5: After the reaction is completed, solid powder will be obtained, and the solid powder will be centrifuged and washed;

[0075] Step 6: Place the washed solid powder in a muffle furnace for sintering while introducing nitrogen. The sintering temperature is 750°C, the sintering time is 3.75h, and the nitrogen ventilation volume is 0.4±0.2cm 3 / h;

[0076] Step 7: Screening the sintered solid powder to obtain the iron-magnesium-doped spherical precursor manganese manganese tetraoxide, wherein the screen is a 225-mesh vibrating screen.

[0077] The tap density of the iron-doped magnesium spherical precursor manganese tetraoxide prepared by this method is 7.83 g / cm 3 , the specific surface area is 0.39m2 / g, and its particle size distribution is: D 50 =7.83μm, D 10 =4.94μm, D 90 =14.65μm.

[0078] Embodiment 5:

[0079] The present invention provides a spherical precursor of iron-doped magnesium-manganese tetraoxide, please refer to Figure 1-Figure 3 The chemical formula of the iron-doped magnesium spherical precursor manganese tetraoxide is: MnFe x Mg y O (8 / 3+3x+2y) / 2 , where 0.001≤x≤0.005, 0.0015≤y≤0.0065.

[0080] The iron-magnesium-doped spherical precursor manganese manganese tetraoxide is in granular form.

[0081] A method for preparing an iron-magnesium-doped spherical precursor manganese tetraoxide comprises the following specific steps:

[0082] Step 1: Manganese sulfate, iron salt and magnesium salt are prepared into a manganese sulfate mixed solution in a certain proportion, wherein the molar ratio of Fe:Mn is 0.005; the molar ratio of Mg:Mn is 0.0065;

[0083] Step 2: Dilute ammonia water to 15% with pure water;

[0084] Step 3: Prepare sodium carbonate solution according to a certain ratio;

[0085] Step 4: adding manganese sulfate mixed solution, ammonia water and sodium carbonate into the reaction kettle in a certain proportion, and controlling the pH value, wherein the pH value is controlled between 8.5;

[0086] Step 5: After the reaction is completed, solid powder will be obtained, and the solid powder will be centrifuged and washed;

[0087] Step 6: Place the washed solid powder in a muffle furnace for sintering while introducing nitrogen. The sintering temperature is 900°C and the sintering time is 4h. The nitrogen ventilation rate is 0.4±0.2cm 3 / h;

[0088] Step 7: Screening the sintered solid powder to obtain the iron-magnesium-doped spherical precursor manganese manganese tetraoxide, wherein the screen is a 250-mesh vibrating screen.

[0089] The tap density of the iron-doped magnesium spherical precursor manganese tetraoxide prepared by this method is 2.77 g / cm 3 , the specific surface area is 0.38m2 / g, and its particle size distribution is: D 50 =7.32μm, D 10 =5.01μm, D 90 =13.54μm.

[0090] The iron-doped magnesium spherical precursor manganese tetraoxide prepared in the above Examples 1-5 was compared to obtain the following data:

[0091]

[0092] It can be seen from the above table that after testing, Example 3 has the best effect.

[0093] Although the present invention has been described above with reference to the embodiments, various modifications may be made thereto and parts thereof may be replaced by equivalents without departing from the scope of the present invention. In particular, as long as there is no structural conflict, the various features in the embodiments disclosed in the present invention may be used in combination with each other in any manner, and the fact that these combinations are not exhaustively described in this specification is only for the sake of omitting space and saving resources. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An iron-doped magnesium-based spherical precursor manganese tetraoxide, characterized in that: The chemical formula of the iron-doped magnesium spherical precursor manganese tetraoxide is: MnFe x Mg y O (8 / 3+3x+2y) / 2 , where 0.001≤x≤0.005, 0.0015≤y≤0.0065.

2. The iron-doped magnesium spherical precursor manganese manganese tetraoxide according to claim 1, characterized in that: The iron-magnesium-doped spherical precursor manganese manganese tetraoxide is in granular form.

3. The iron-doped magnesium spherical precursor manganese tetraoxide according to claim 2, characterized in that: The particle size distribution of the iron-doped magnesium-like spherical precursor manganese tetraoxide is: 50 =6.0~12.0μm, D 10 ≥4.0μm, D 90 ≤25μm.

4. A method for preparing an iron-magnesium-doped spherical precursor manganese tetraoxide, characterized in that: The specific steps are as follows: Step 1: preparing manganese sulfate, iron salt and magnesium salt in a certain proportion into a manganese sulfate mixed solution; Step 2: Dilute ammonia water to 15% with pure water; Step 3: Prepare sodium carbonate solution according to a certain ratio; Step 4: adding manganese sulfate mixed solution, ammonia water and sodium carbonate into the reaction kettle in a certain proportion, and controlling the pH value; Step 5: After the reaction is completed, solid powder will be obtained, and the solid powder will be centrifuged and washed; Step 6: placing the washed solid powder in a muffle furnace for sintering while introducing nitrogen; Step 7: Screen the sintered solid powder to obtain the iron-magnesium-doped spherical precursor manganese manganese tetraoxide.

5. The method for preparing the iron-doped magnesium spherical precursor manganese tetraoxide according to claim 4, characterized in that: In the step 1, the molar ratio of Fe:Mn is 0.001≤x≤0.005; the molar ratio of Mg:Mn is 0.0015≤y≤0.0065.

6. The method for preparing the iron-doped magnesium spherical precursor manganese tetraoxide according to claim 4, characterized in that: In the step 4, the pH value is controlled between 6.0 and 8.

5.

7. The method for preparing the iron-doped magnesium spherical precursor manganese tetraoxide according to claim 4, characterized in that: In step six, the sintering temperature is 300-900° C. and the sintering time is 3-4 hours.

8. The method for preparing the iron-doped magnesium spherical precursor manganese tetraoxide according to claim 4, characterized in that: The nitrogen ventilation volume in step 6 is 0.4±0.2cm 3 / h.

9. The method for preparing the iron-doped magnesium spherical precursor manganese tetraoxide according to claim 4, characterized in that: In the step 7, the screen is a 150-250 mesh vibrating screen.

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