Ferromanganese oxide material and preparation method thereof

Abstract

The invention discloses a ferromanganese oxide material and a preparation method thereof, and relates to the technical field of lithium ion battery precursor material preparation. The method comprises the following steps: preparing a mixed salt solution A containing a manganese element and an iron element; preparing a mixed alkali solution B containing alkali and soluble carbonate; gradually dropwise adding the mixed solution A into the mixed alkali solution B under stirring, controlling the dropwise adding speed of the solution A and the pH value of the whole system to be 9-12, continuously stirring for a period of time after dropwise adding is completed, and then carrying out nucleation crystallization, cooling, filtering and washing to obtain a filter cake; doping a surfactant, drying, and calcining at a certain temperature to obtain a ferromanganese oxide; the method is simple and easy to operate, the manganese element and the iron element can be uniformly mixed at the atomic level, the prepared ferromanganese oxide has relatively high chemical stability, the phenomena of atom segregation and the like cannot occur under high-temperature treatment, and the lithium manganese iron phosphate positive electrode material with good uniformity, high purity and excellent performance can be further prepared.

Description

Technical Field

[0001] The invention relates to the technical field of lithium ion battery precursor material preparation, in particular to a manganese iron oxide material and a preparation method thereof. Background Art

[0002] Lithium iron phosphate (LFP) has been widely used as anode material for lithium-ion batteries due to its abundant raw material sources, low price, environmental friendliness, good thermal stability, good cycle performance and safety, and plays an important role in high-power electric tools, energy storage equipment, light electric vehicles, portable mobile device power supplies and other fields. However, with the rapid development of the new energy industry in recent years, the electrochemical energy storage industry has also experienced explosive growth. LFP can no longer meet the current market demand for high-energy density batteries due to its low operating voltage, insufficient rate performance, and low electronic conductivity. Lithium iron manganese phosphate (LFMP) is a material in which a certain proportion of manganese is doped in lithium iron phosphate. Manganese and iron are located in adjacent positions on the periodic table, with similar ionic radii and similar chemical properties. Therefore, the doping of manganese will not significantly change the structure of lithium iron phosphate. In addition, thanks to the high voltage characteristics of manganese, at the same specific capacity, the energy density of LFMP is 10-20% higher than that of LFP, and the low-temperature performance is also improved. It is expected to become a new generation of high-energy density power battery cathode material.

[0003] The methods for preparing LMFP reported in the literature include spray drying, sol-gel method, coprecipitation method, high-temperature solid phase method, etc. Among them, the solid phase method is considered to be most suitable for industrial large-scale production due to its simple process, easy process control, and high yield. The solid phase method is to mix and grind the solid phase manganese source, iron source, lithium source and phosphorus source and further calcine at high temperature to prepare lithium manganese iron phosphate. This mixed grinding method is usually difficult to achieve uniform mixing of manganese source and iron source at the atomic level, the nano-level is not high, and the obtained product is prone to unevenness, low purity, large size and other problems. Therefore, a manganese iron oxide material and its preparation method are urgently needed to solve this problem. Summary of the invention

[0004] The object of the present invention is to provide a manganese iron oxide material and a preparation method thereof to solve the problems mentioned in the background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for preparing a manganese iron oxide material, comprising the following specific steps:

[0006] S1. Prepare a mixed salt solution A containing manganese and iron elements;

[0007] S2. configuring a mixed alkaline solution B comprising an alkali and a soluble carbonate;

[0008] S3. The mixed salt solution A is gradually added dropwise to the mixed alkali solution B under stirring, and the dropping speed of the mixed salt solution A and the pH value of the whole system are controlled to be between 9 and 12. After the addition is completed, stirring is continued for a period of time, and then the filter cake is obtained by nucleation crystallization, cooling, filtering and washing;

[0009] S4. After adding a surfactant into the filter cake, the filter cake is dried and then placed in a muffle furnace and calcined at a certain temperature to obtain manganese iron oxide.

[0010] Preferably, in the above step S1, the total ion concentration of manganese and iron in the mixed salt solution A is 0.6-6 mol / L, and the molar ratio of manganese to iron is (2-4):1.

[0011] Preferably, in the above step S1, the iron salt is one or more of ferric chloride, ferric nitrate, and ferric sulfate, and the manganese salt is one or more of manganese chloride, manganese nitrate, and manganese sulfate.

[0012] Preferably, in the above step S2, the base is sodium hydroxide or potassium hydroxide with a concentration of 0.5 to 3 mol / L.

[0013] Preferably, in the above step S2, the soluble carbonate is one or more of sodium carbonate, ammonium carbonate, ammonium bicarbonate, and potassium carbonate, and the concentration is 0.1-1 mol / L.

[0014] Preferably, in the above step S3, the mixed salt solution A is added dropwise to the mixed alkali solution B at a rate of 2 to 5 ml / min, and stirring is continued for 2 to 10 hours after the addition is completed.

[0015] Preferably, in the above step S3, the reaction product after the mixed salt solution A is mixed with the mixed alkali solution B is nucleated and crystallized at 60-90° C. for 6-24 hours, and then cooled, filtered, and washed with deionized water to neutrality.

[0016] Preferably, in the above step S4, the surfactant is one or more of polyethylene glycol, sodium dodecyl sulfate, and sodium oleate, and the added amount is 0.1-1% of the total mass of the manganese salt and the iron salt added to the mixed salt solution A.

[0017] Preferably, in the above step S4, the filter cake is dried at a temperature of 60 to 90° C. for 10 to 24 hours, and the dried material is calcined in a muffle furnace at a temperature of 400 to 700° C. for 4 to 8 hours.

[0018] Another technical solution provided by the present invention is: a manganese iron oxide material prepared by the above preparation method, whose chemical formula is Mn 3-x Fe xO4, wherein 0.6≤x≤1, the molar ratio of manganese to iron is (2-4):1, manganese and iron are evenly mixed, have high chemical stability, and will not undergo atomic segregation under high temperature conditions for the preparation of battery positive electrode materials.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The manganese iron oxide material and the preparation method thereof can achieve uniform mixing of manganese and iron elements at the atomic level, and the ratio of the two can be controlled from the raw material end. At the same time, the obtained manganese iron oxide has high chemical stability and will not undergo atomic segregation under high-temperature treatment, which is conducive to the preparation of lithium manganese iron phosphate positive electrode materials with good uniformity, high purity and excellent performance in the subsequent production process.

[0021] 2. The preparation method of the manganese iron oxide material has simple and reasonable steps, a mild and easy-to-operate process, and is suitable for industrial production applications. The obtained manganese iron oxide precursor has a small overall particle size, which can effectively reduce the time of mechanical grinding in the solid-phase preparation of lithium manganese iron phosphate, and is also conducive to better control of the product size of lithium manganese iron phosphate. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the SEM image of the manganese iron oxide prepared in Example 3.

[0023] Figure 2 This is the XRD pattern of the manganese iron oxide prepared in Example 3;

[0024] Figure 3 This is a SEM image of the ferromanganese oxide prepared in Example 3 after high-temperature heat treatment again;

[0025] Figure 4 This is the Mn element distribution diagram of the ferromanganese oxide prepared in Example 3 after high-temperature heat treatment again;

[0026] Figure 5 This is the Fe element distribution diagram of the manganese iron oxide prepared in Example 3 after high-temperature heat treatment again. DETAILED DESCRIPTION

[0027] A method for preparing a manganese iron oxide material comprises the following specific steps:

[0028] S1. Prepare a mixed salt solution A containing manganese and iron elements;

[0029] S2. configuring a mixed alkaline solution B comprising an alkali and a soluble carbonate;

[0030] S3. The mixed salt solution A is gradually added dropwise to the mixed alkali solution B under stirring, and the dropping speed of the mixed salt solution A and the pH value of the whole system are controlled to be between 9 and 12. After the addition is completed, stirring is continued for a period of time, and then the filter cake is obtained by nucleation crystallization, cooling, filtering and washing;

[0031] S4. After adding a surfactant into the filter cake, the filter cake is dried and then placed in a muffle furnace and calcined at a certain temperature to obtain manganese iron oxide.

[0032] In step S1, the total ion concentration of manganese and iron in the mixed salt solution A is 0.6-6 mol / L, and the molar ratio of manganese to iron is (2-4):1.

[0033] In step S1, the iron salt is one or more of ferric chloride, ferric nitrate, and ferric sulfate, and the manganese salt is one or more of manganese chloride, manganese nitrate, and manganese sulfate.

[0034] In step S2, the base is sodium hydroxide or potassium hydroxide, and the concentration is 0.5-3 mol / L.

[0035] In step S2, the soluble carbonate is one or more of sodium carbonate, ammonium carbonate, ammonium bicarbonate, and potassium carbonate, with a concentration of 0.1 to 1 mol / L.

[0036] In step S3, the mixed salt solution A is added dropwise to the mixed alkali solution B at a rate of 2 to 5 ml / min, and stirring is continued for 2 to 10 hours after the addition is completed.

[0037] In step S3, the reaction product after the mixed salt solution A is mixed with the mixed alkali solution B is nucleated and crystallized at 60-90° C. for 6-24 hours, and then cooled, filtered, and washed with deionized water until neutral.

[0038] In step S4, the surfactant is one or more of polyethylene glycol, sodium dodecyl sulfate, and sodium oleate, and the added amount is 0.1-1% of the total mass of the manganese salt and the iron salt added to the mixed salt solution A.

[0039] In step S4, the filter cake is dried at a temperature of 60 to 90° C. for 10 to 24 hours, and the dried material is calcined in a muffle furnace at a temperature of 400 to 700° C. for 4 to 8 hours.

[0040] A manganese iron oxide material prepared by the above preparation method, whose chemical formula is Mn 3-x Fe x O4, wherein 0.6≤x≤1, the molar ratio of manganese to iron is (2-4):1, manganese and iron are evenly mixed, have high chemical stability, and will not undergo atomic segregation under high temperature conditions for the preparation of battery positive electrode materials.

[0041] Embodiment 1:

[0042] (1) Preparing a mixed salt solution A: Dissolve FeCl3·6H2O and MnCl2·4H2O in deionized water to obtain a solution A having a total manganese and iron concentration of 3 mol / L, wherein the molar ratio of manganese to iron is 2:1.

[0043] (2) Prepare mixed alkaline solution B: Prepare mixed alkaline solution B containing 1.5 mol / L NaOH and 0.5 mol / L Na2CO3, where CO3 2- The amount of substance is Fe 3+ 1.5 times of.

[0044] (3) Under stirring conditions, solution A was added dropwise to solution B at a rate of 2 ml / min. After the addition was completed, stirring was continued for 3 h, maintaining the pH at 10, and then crystallized at 70 °C for 12 h. After that, the solution was cooled, filtered, and washed with deionized water until neutral.

[0045] (4) 0.8 g of polyethylene glycol was added to the washed filter cake and dried in an oven at 70° C. for 10 h. The dried material was then calcined in a muffle furnace at 500° C. for 4 h to obtain manganese iron oxide.

[0046] Embodiment 2:

[0047] (1) Preparing a mixed salt solution A: Dissolve FeCl3·6H2O and MnCl2·4H2O in deionized water to obtain a solution A having a total manganese and iron concentration of 3 mol / L, wherein the molar ratio of manganese to iron is 4:1.

[0048] (2) Prepare mixed alkaline solution B: Prepare mixed alkaline solution B containing 3 mol / L NaOH and 1 mol / L Na2CO3, where CO3 2- The amount of substance is Fe 3+ 1.5 times of.

[0049] (3) Under stirring conditions, solution A was added dropwise to solution B at a rate of 2 ml / min. After the addition was completed, stirring was continued for 3 h, maintaining the pH at 12, and then crystallized at 70 °C for 12 h. After that, the solution was cooled, filtered, and washed with deionized water until neutral.

[0050] (4) 0.8 g of sodium dodecyl sulfate was added to the washed filter cake and dried in an oven at 80° C. for 6 h. The dried material was then calcined in a muffle furnace at 600° C. for 6 h to obtain manganese iron oxide.

[0051] Embodiment 3:

[0052] (1) Preparing a mixed salt solution A: Dissolve Fe2(SO4)3·9H2O and MnSO4·H2O in deionized water to obtain a solution A having a total manganese and iron concentration of 2 mol / L, wherein the molar ratio of manganese to iron is 2:1.

[0053] (2) Prepare mixed alkaline solution B: Prepare mixed alkaline solution B containing 1 mol / L NaOH and 0.5 mol / L Na2CO3, where CO3 2- The amount of substance is Fe 3+ 1.5 times of.

[0054] (3) Under stirring conditions, solution A was added dropwise to solution B at a rate of 4 ml / min. After the addition was completed, stirring was continued for 5 h, maintaining the pH at 10, and then crystallized at 80 °C for 12 h. After that, the solution was cooled, filtered, and washed with deionized water until neutral.

[0055] (4) 0.8 g of sodium dodecyl sulfate was added to the washed filter cake and dried in an oven at 60° C. for 10 h. The dried material was then calcined in a muffle furnace at 400° C. for 5 h to obtain manganese iron oxide.

[0056] Embodiment 4:

[0057] (1) Preparing a mixed salt solution A: Dissolve Fe2(SO4)3·9H2O and MnSO4·H2O in deionized water to obtain a solution A having a total manganese and iron concentration of 2 mol / L, wherein the molar ratio of manganese to iron is 3:1.

[0058] (2) Prepare mixed alkaline solution B: Prepare mixed alkaline solution B containing 2 mol / L NaOH and 0.5 mol / L Na2CO3, where CO3 2- The amount of substance is Fe 3+ 1.5 times of.

[0059] (3) Under stirring conditions, solution A was added dropwise to solution B at a rate of 4 ml / min. After the addition was completed, stirring was continued for 3 h, maintaining the pH at 11, and then crystallized at 90 °C for 12 h. After that, the solution was cooled, filtered, and washed with deionized water until neutral.

[0060] (4) 0.6 g of sodium oleate was added to the washed filter cake and dried in an oven at 70° C. for 10 h. The dried material was then calcined in a muffle furnace at 700° C. for 4 h to obtain ferromanganese oxide.

[0061] Embodiment 5:

[0062] (1) Prepare mixed salt solution A: Dissolve Fe(NO3)3·9H2O and Mn(NO3)2·4H2O in deionized water to obtain solution A with a total manganese and iron concentration of 3 mol / L, wherein the molar ratio of manganese element to iron element is 2:1.

[0063] (2) Prepare mixed alkaline solution B: Prepare mixed alkaline solution B containing 3 mol / L NaOH and 1 mol / L Na2CO3, where CO3 2- The amount of substance is Fe 3+ 1.5 times of.

[0064] (3) Under stirring conditions, solution A was added dropwise to solution B at a rate of 3 ml / min. After the addition was completed, stirring was continued for 3 h, maintaining the pH at 12, and then crystallized at 70 °C for 12 h. After that, the solution was cooled, filtered, and washed with deionized water until neutral.

[0065] (4) 1.6 g of polyethylene glycol was added to the washed filter cake and dried in an oven at 80° C. for 10 h. The dried material was then calcined in a muffle furnace at 600° C. for 6 h to obtain manganese iron oxide.

[0066] Embodiment 6:

[0067] The manganese iron oxides prepared in Examples 1 to 5 were placed in a muffle furnace respectively, and heated to 400°C at a heating rate of 3°C / min in a nitrogen atmosphere, and kept at that temperature for 2 hours, and then heated to 750°C at a heating rate of 1°C / min and kept at that temperature for 6 hours. After cooling to room temperature, no atomic segregation was found.

[0068] Taking Example 3 as an example, Figure 1 It shows that its size is small and uniform. Figures 3 to 5 It can be seen that after the second heat treatment, there is no obvious change in its morphology and size, and the distribution of manganese and iron elements remains uniform, indicating that it has high stability. When it is used as a precursor to prepare battery positive electrode materials, it is beneficial to obtain products with good uniformity, high purity and excellent performance.

[0069] The above are only preferred embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope defined by the claims.

[0070] The matters not described in detail in the present invention are all known technologies to those skilled in the art.

Claims

1. A method for preparing a manganese iron oxide material, characterized in that: The specific steps include: S1. Prepare a mixed salt solution A containing manganese and iron elements; S2. configuring a mixed alkaline solution B comprising an alkali and a soluble carbonate; S3. The mixed salt solution A is gradually added dropwise to the mixed alkali solution B under stirring, and the dropping speed of the mixed salt solution A and the pH value of the whole system are controlled to be between 9 and 12. After the addition is completed, stirring is continued for a period of time, and then the filter cake is obtained by nucleation crystallization, cooling, filtering and washing; S4. After adding a surfactant into the filter cake, the filter cake is dried and then placed in a muffle furnace and calcined at a certain temperature to obtain manganese iron oxide.

2. The method for preparing a manganese iron oxide material according to claim 1, characterized in that: In step S1, the total ion concentration of manganese and iron in the mixed salt solution A is 0.6-6 mol / L, and the molar ratio of manganese to iron is (2-4):

1.

3. The method for preparing a manganese iron oxide material according to claim 1, characterized in that: In step S1, the iron salt is one or more of ferric chloride, ferric nitrate, and ferric sulfate, and the manganese salt is one or more of manganese chloride, manganese nitrate, and manganese sulfate.

4. The method for preparing a manganese iron oxide material according to claim 1, characterized in that: In step S2, the alkali is sodium hydroxide or potassium hydroxide, and the concentration is 0.5-3 mol / L.

5. The method for preparing a manganese iron oxide material according to claim 1, characterized in that: In step S2, the soluble carbonate is one or more of sodium carbonate, ammonium carbonate, ammonium bicarbonate, and potassium carbonate, and the concentration is 0.1-1 mol / L.

6. The method for preparing a manganese iron oxide material according to claim 1, characterized in that: In step S3, the mixed salt solution A is added dropwise to the mixed alkali solution B at a rate of 2 to 5 ml / min, and stirring is continued for 2 to 10 hours after the addition is completed.

7. The method for preparing a manganese iron oxide material according to claim 1, characterized in that: In the step S3, the reaction product after the mixed salt solution A is mixed with the mixed alkali solution B is nucleated and crystallized at 60-90° C. for 6-24 hours, then cooled, filtered, and washed with deionized water until neutral.

8. The method for preparing a manganese iron oxide material according to claim 1, characterized in that: In step S4, the surfactant is one or more of polyethylene glycol, sodium lauryl sulfate, and sodium oleate, and the added amount is 0.1-1% of the total mass of the manganese salt and the iron salt added to the mixed salt solution A.

9. The method for preparing a manganese iron oxide material according to claim 1, characterized in that: In step S4, the filter cake is dried at a temperature of 60 to 90° C. for 10 to 24 hours, and the dried material is calcined in a muffle furnace at a temperature of 400 to 700° C. for 4 to 8 hours.

10. A manganese iron oxide material prepared by the preparation method according to any one of claims 1 to 9, characterized in that: The chemical formula of the manganese iron oxide is Mn 3-x Fe x O4, wherein 0.6≤x≤1, the molar ratio of manganese to iron is (2-4):1, manganese and iron are evenly mixed, have high chemical stability, and will not undergo atomic segregation under high temperature conditions for the preparation of battery positive electrode materials.

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