Preparation method of low-cost lithium manganate material

Abstract

The invention discloses a preparation method of a low-cost lithium manganate material, and belongs to the technical field of new energy lithium battery materials. The method comprises the following steps: (1) pretreatment: putting manganous-manganic oxide, lithium carbonate and doped metal elements into equipment, and fully mixing to obtain a mixture; and (2) sintering: calcining the mixture in a rotary furnace. And (3) post-treatment: crushing the cooled material, sieving, and removing iron to obtain the lithium manganate. According to the invention, low-cost manganous-manganic oxide is used as a synthesis raw material, a rotary furnace is used as a sintering carrier, and a dynamic synthesis mode is adopted, so that the sufficient reaction of the materials is facilitated, the yield is not limited, the sintering time and the sintering temperature are greatly reduced, the energy consumption is reduced in a disguised manner, the yield is improved, and meanwhile, the consistency of the product is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy lithium battery materials, and in particular to a method for preparing a low-cost lithium manganate material. Background Art

[0002] Lithium-ion batteries have been promoted worldwide as a new energy industry. Lithium manganese oxide, as a type of positive electrode material for lithium-ion batteries, has always been the focus of research and development in the industry, and is widely used in digital products, power tools, electric vehicles and electric vehicles. Compared with materials such as lithium iron phosphate and nickel cobalt lithium manganese oxide, lithium manganese oxide is more cost-effective and often has the lowest cost.

[0003] Traditional lithium manganese oxide production includes mixing, sintering, crushing, screening, iron removal, packaging and other processes. Among them, sintering is the process with the largest cost, accounting for more than 60% of the production cost. Optimizing the sintering mode can greatly reduce the production cost of the material.

[0004] The existing lithium manganate sintering process generally uses a tunnel furnace or a roller furnace, which is a static synthesis method of loading materials in a sagger. This synthesis method has a small output, a high ton consumption, and uneven heating, resulting in poor product consistency. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of the prior art, provide a lower-cost manganese tetraoxide as a synthetic raw material, use a rotary kiln as a sintering carrier, and adopt a dynamic synthesis method, which is conducive to the full reaction of the material, so that the output is not limited, and the sintering time and sintering temperature are greatly reduced, which reduces energy consumption in disguise and increases the output, and at the same time the consistency of the product is improved.

[0006] In order to achieve the above-mentioned invention object, the present invention adopts the following technical solution: a method for preparing a low-cost lithium manganese oxide material, comprising the following steps:

[0007] (1) Pretreatment: Manganese tetraoxide, lithium carbonate, and doped metal elements are placed in a device and mixed thoroughly to obtain a mixture;

[0008] (2) Sintering: Place the mixed material in a rotary kiln for calcination, let in air, and then start heating. Heating time: 2 to 3 hours; constant temperature time: 4 to 6 hours; cooling time: 4 to 6 hours. Constant temperature: 650 to 750°C.

[0009] (3) Post-processing: The cooled material is crushed, screened, and iron removed to obtain lithium manganese oxide.

[0010] Furthermore, the D50 of the manganese tetraoxide particles in step (1) is 3-8 μm.

[0011] Furthermore, the lithium carbonate particles in step (1) have a D50 of 4-7 μm.

[0012] Furthermore, the molar ratio of manganese tetraoxide to lithium carbonate in step (1) is (1-1.3):1.

[0013] Furthermore, the amount of the metal element added in step (1) is 0.1% to 1% of the mass of trimanganese tetraoxide.

[0014] Furthermore, the mixing time of step (1) is 60-120 min, and the rotation speed is 30-50 rpm.

[0015] Furthermore, the air intake volume of step (2) is 100-200m 3 / h.

[0016] Furthermore, the heating rate of step (2) is 5°C / min.

[0017] Furthermore, the metal element in step (1) is nano-scale aluminum, titanium, magnesium, zirconium or niobium metal oxide.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) The preparation method of the present invention reduces the sintering cycle and sintering temperature of the material.

[0020] (2) The preparation method of the present invention is not affected by factors such as raw materials, and greatly improves the sintering output.

[0021] (3) The present invention uses a rotary kiln as a sintering carrier and a dynamic synthesis method, which ensures uniform heating, sufficient reaction, and better product consistency.

[0022] (4) The preparation method of the present invention eliminates the need for furnace inlet and outlet devices and circulation lines, thereby simplifying the production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0024] Figure 1 It is a scanning electron microscope with a magnification of 1000 times that of the lithium manganate material in Example 1 of the present invention.

[0025] Figure 2 It is a scanning electron microscope 1000 times larger than the lithium manganese oxide material of comparative example 1 of the present invention.

[0026] Figure 3 It is the charge and discharge cycle curve diagram of Example 1 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0028] Example 1

[0029] The embodiment of the present invention provides a method for preparing a low-cost lithium manganese oxide material, comprising the following steps:

[0030] (1) Select single crystal manganese tetraoxide with D50:5um and lithium carbonate with D50:6um respectively, weigh manganese tetraoxide, lithium carbonate and nano-alumina in proportion: 843kg, 224kg and 2kg respectively; put them into the inclined mixer in order, and mix them at a speed of 30rpm for 90 minutes. After the end, measure the lithium content. If it is unqualified, mix it for another 30 minutes.

[0031] (2) The qualified mixed materials are put into the rotary furnace at a uniform speed, the parameters are 5℃ / min and raised to 720℃, kept at a constant temperature for 6 hours, and discharged after cooling for 6 hours. Air is introduced throughout the process, and the flow rate is 200m 3 / h.

[0032] (3) The sintered material is crushed, sieved, and iron removed to obtain lithium manganese oxide material, and a sample is taken for SEM testing (see Figure 1 ) and withholding power (see Figure 3 The charge and discharge data of the finished half-battery are at room temperature of 45°C, with a rate of 1C and a voltage of 3.0V to 4.3V.

[0033] Comparative Example 1

[0034] Using traditional sintering process

[0035] (1) Select single crystal manganese tetraoxide with D50:5um and lithium carbonate with D50:6um respectively, weigh manganese tetraoxide, lithium carbonate and nano-alumina in proportion: 843kg, 224kg and 2kg respectively; put them into the inclined mixer in order, and mix them at a speed of 30rpm for 90 minutes. After the end, measure the lithium content. If it is unqualified, mix it for another 30 minutes.

[0036] (2) The qualified mixed materials are put into the roller furnace at a uniform speed, the parameters are 3℃ / min and raised to 800℃, kept at a constant temperature for 10 hours, cooled for 6 hours and then discharged, and air is introduced throughout the process, with a flow rate of 200m 3 / h.

[0037] (1) After sintering, the material is crushed, screened, and iron removed to obtain the material we need to produce. Samples are taken for SEM testing (see Figure 2 ) and withholding power (see Figure 3The charge and discharge data of the finished half-battery are at room temperature of 45°C, with a rate of 1C and a voltage of 3.0V to 4.3V.

[0038] Test Results

[0039] pass Figure 1 and Figure 2 By comparison, the sintering scheme adopted by the present invention and the traditional sintering scheme have a complete product crystal structure, a close fit on the crystal surface, and a uniform distribution, and the overall effect is relatively good. Figure 3 Compared with the cycle performance, the scheme of the present invention has better performance. In terms of energy consumption, the sintering cycle of the scheme of the present invention is shortened by 6 hours, the temperature is reduced by 80°C, and compared with the traditional sintering process, the overall ton consumption is reduced by more than 30%.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a low-cost lithium manganate material, characterized in that: The steps include: (1) Pretreatment: Manganese tetraoxide, lithium carbonate, and doped metal elements are placed in a device and mixed thoroughly to obtain a mixture; (2) Sintering: Place the mixed material in a rotary kiln for calcination, introduce air, and then start heating. Heating time: 2 to 3 hours; constant temperature time: 4 to 6 hours; cooling time: 4 to 6 hours. Constant temperature: 650 to 750°C; (3) Post-processing: The cooled material is crushed, screened, and iron removed to obtain lithium manganese oxide.

2. The method for preparing low-cost lithium manganate material according to claim 1, characterized in that: The D50 of the manganese tetraoxide particles in step (1) is 3-8 μm.

3. The method for preparing low-cost lithium manganate material according to claim 1, characterized in that: The D50 of the lithium carbonate particles in step (1) is 4-7 μm.

4. The method for preparing low-cost lithium manganate material according to claim 1, characterized in that: The molar ratio of trimanganese tetraoxide to lithium carbonate in the step (1) is (1-1.3):

1.

5. The method for preparing low-cost lithium manganate material according to claim 1, characterized in that: The amount of the metal element added in step (1) is 0.1% to 1% of the mass of trimanganese tetraoxide.

6. The method for preparing low-cost lithium manganate material according to claim 1, characterized in that: The mixing time of step (1) is 60-120 min, and the rotation speed is 30-50 rpm.

7. The method for preparing low-cost lithium manganate material according to claim 1, characterized in that: The air intake volume of step (2) is 100-200m 3 / h, and the heating rate of step (2) is 5°C / min.

8. The method for preparing low-cost lithium manganate material according to claim 1, characterized in that: The metal element in step (1) is nano-scale aluminum, titanium, magnesium, zirconium or niobium metal oxide.

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