Preparation method and application of lithium manganate material

Abstract

The invention discloses a preparation method of a lithium manganate material, and belongs to the technical field of lithium batteries. According to the technical scheme, the preparation method comprises the following steps: preparing a lithium manganate material: uniformly mixing a manganese source and a lithium source according to a molar ratio, putting the mixture into a box-type resistance furnace for high-temperature sintering, and cooling to room temperature to obtain the lithium manganate material; wherein the lithium carbonate accounts for 8-10 parts, the manganese acetate accounts for 15-25 parts, the ferric acetate accounts for 2-5 parts, the lead acetate accounts for 0.5-2 parts, the nickel acetate accounts for 0.3-1.2 parts, the citric acid accounts for 8-25 parts, and the deionized water accounts for 100-120 parts. The dry powder mixer is utilized to uniformly mix the positive and negative electrode powder in advance, so that the slurry stirring time is shortened, the problem that the powder material is difficult to uniformly disperse is solved, and the consistency of the slurry is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium batteries, and in particular relates to a preparation method and application of a lithium manganate material. Background Art

[0002] Lithium battery is a primary battery that uses lithium metal or lithium alloy as negative electrode material and non-aqueous electrolyte solution. It is different from rechargeable lithium-ion battery and lithium-ion polymer battery. The inventor of lithium battery is Edison. Due to the very active chemical properties of lithium metal, the processing, storage and use of lithium metal have very high environmental requirements. Therefore, lithium battery has not been used for a long time. At present, the commercialized power battery is mainly lead-acid battery. The battery has exposed obvious defects in the long-term use process, such as low specific energy, large self-discharge, serious pollution, etc., which makes it difficult to meet the use requirements of pure electric vehicles. Lithium-ion battery has many advantages such as high specific energy, long cycle life, small self-discharge, safety and reliability, green and environmental protection, etc., and has attracted widespread attention from all walks of life. Among the positive electrode materials of power batteries, lithium manganese oxide has the advantages of low cost, good safety and excellent rate performance, and is considered to be the most cost-effective positive electrode material for power batteries. However, the problem faced by lithium manganese oxide material is that the cycle performance is not ideal, and it needs to be modified in order to achieve large-scale commercial use. Summary of the invention

[0003] The present invention provides a preparation method and application of a lithium manganate material to solve the above problems.

[0004] The technical solution of the present invention is: The invention discloses a method for preparing a lithium manganate material. The preparation method of the lithium manganate material comprises the following steps: uniformly mixing a manganese source and a lithium source according to a molar ratio, sintering the mixture in a box-type resistance furnace at a high temperature, and cooling the mixture to room temperature to obtain the lithium manganate material; wherein the mixture comprises 8-10 parts of lithium carbonate, 15-25 parts of manganese acetate, 2-5 parts of iron acetate, 0.5-2 parts of lead acetate, 0.3-1.2 parts of nickel acetate, 8-25 parts of citric acid, and 100-120 parts of deionized water.

[0005] Preferably, lithium carbonate and electrolytic manganese dioxide are uniformly mixed in a molar ratio of 1:1.5, placed in a box-type resistance furnace and sintered at 700° C. for 12 hours under a nitrogen protective atmosphere, then cooled to room temperature, and the product is taken out and sieved to obtain a lithium manganate material.

[0006] Preferably, the high temperature sintering temperature is 600-800° C., and the sintering time is 8-15 hours.

[0007] Preferably, lithium carbonate and electrolytic manganese dioxide are uniformly mixed in a molar ratio of 1:1.5, placed in a box-type resistance furnace and sintered at 700° C. for 12 hours under a nitrogen protective atmosphere, then cooled to room temperature, and the product is taken out and sieved to obtain a lithium manganate material.

[0008] In a second aspect, a method for preparing a battery using the lithium manganate material is disclosed. S1: Preparation of a composite material of lithium manganate and carbon nanotubes. Chemically purified carbon nanotubes are ball-milled and mixed with the prepared lithium manganate material to obtain a composite material of lithium manganate and carbon nanotubes. S2: Positive electrode active material, negative electrode active material, and conductive agent: The positive electrode active substance uses a composite material of lithium manganate and carbon nanotubes. The conductive agent is a mixture of conductive carbon black and KS-6. The negative electrode active substance uses modified mesophase carbon microspheres, and the conductive agent is conductive carbon black. Pulp is prepared using a dry powder mixer and a high-speed stirrer. S3: Battery preparation: The positive electrode active material, negative electrode active material, and conductive agent are used to prepare pulp using a dry powder mixer and a high-speed stirrer.

[0009] Preferably, the positive electrode material of the lithium manganate battery doped with Ni, Fe, and Pb is prepared by the following method: Lithium carbonate, manganese acetate, iron acetate, lead acetate, nickel acetate, and citric acid are dissolved in deionized water in proportion. Ammonia water is used to adjust the pH to 8, and the solution is heated in a water bath at 70 - 80 °C until a gel is formed. The gel is placed in a drying oven and dried at 100 °C to obtain a dry gel, which is pretreated in an argon atmosphere at 400 °C for 7 - 10 h and then calcined at 800 - 1000 °C for 12 - 15 h. After cooling to room temperature, it is ground to obtain the product.

[0010] Preferably, the multi-walled carbon nanotubes are chemically purified before use.

[0011] In a third aspect, the application of the lithium manganate battery in the lithium battery industry is disclosed.

[0012] Compared with the prior art, the present invention has the following beneficial effects: 1. Using a dry powder mixer to pre-uniformly mix the positive and negative electrode powders shortens the slurry stirring time, solves the problem of difficult uniform dispersion of powder materials, and improves the consistency of the slurry.

[0013] 2. The battery of the present invention has excellent room temperature cycling performance. The discharge specific capacity at 0.5C is 118 mAh / g, and the capacity retention rate after 1750 cycles at 1C is 80%. Specific Embodiments

[0014] Example 1 A method for preparing a battery from the lithium manganese oxide material, wherein the lithium manganese oxide material and the chemically purified carbon nanotubes are ball-milled to obtain a composite material of lithium manganese oxide and carbon nanotubes, wherein the positive electrode active material is a composite material of lithium manganese oxide and carbon nanotubes, the conductive agent is a mixture of conductive carbon black and KS-6, and the negative electrode active material is modified mesophase carbon microspheres, the conductive agent is conductive carbon black, and the slurry is prepared using a dry powder mixer and a high-speed mixer. In this embodiment, the carbon nanotubes are multi-walled carbon nanotubes with a tube diameter of 8nm and a tube length of 12μm. In this embodiment, the multi-walled carbon nanotubes are chemically purified before use. In this embodiment, the lithium manganese oxide material and the carbon nanotubes are ball-milled and mixed, and the amount of carbon nanotubes added is 0.8%% of the total amount of the conductive agent.

[0015] First, add the carbon nanotube sample to concentrated nitric acid solution, and after ultrasonic oscillation for a few minutes, reflux at 120℃ for 4 hours under magnetic stirring, and obtain high-purity carbon nanotubes after centrifugation, washing and drying. Then, mix the purified carbon nanotubes with lithium manganate material and ball mill to obtain a composite material, in which the amount of carbon nanotubes added is 1% of the total amount of conductive agent.

[0016] Example 2 A method for preparing a lithium manganate material, first mixing a lithium source and a manganese source in a molar ratio, placing them in a box-type resistance furnace for high-temperature sintering, and cooling them to room temperature to obtain a lithium manganate material. In this embodiment, the molar ratio of the lithium source to the manganese source is 1: 1.5. In this embodiment, the high-temperature sintering temperature is 800°C and the sintering time is 15h. In this embodiment, lithium carbonate and electrolytic manganese dioxide are mixed in a molar ratio of 1:1.5, placed in a box-type resistance furnace, sintered at 700°C for 12h under a nitrogen protective atmosphere, and then cooled to room temperature. The product is taken out and sieved to obtain a lithium manganate material.

[0017] A method for preparing a battery from the lithium manganese oxide material, wherein the lithium manganese oxide material and the chemically purified carbon nanotubes are ball-milled to obtain a composite material of lithium manganese oxide and carbon nanotubes, wherein the positive electrode active material is a composite material of lithium manganese oxide and carbon nanotubes, the conductive agent is a mixture of conductive carbon black and KS-6, and the negative electrode active material is modified mesophase carbon microspheres, the conductive agent is conductive carbon black, and the slurry is prepared using a dry powder mixer and a high-speed stirrer. In this embodiment, the carbon nanotubes are multi-walled carbon nanotubes with a tube diameter of 10 nm and a tube length of 24 μm. In this embodiment, the multi-walled carbon nanotubes are chemically purified before use. In this embodiment, the lithium manganese oxide material and the carbon nanotubes are ball-milled and mixed, and the amount of carbon nanotubes added is 1.5% of the total amount of the conductive agent.

[0018] First, add the carbon nanotube sample to concentrated nitric acid solution, and after ultrasonic oscillation for a few minutes, reflux at 120℃ for 4 hours under magnetic stirring, and obtain high-purity carbon nanotubes after centrifugation, washing and drying. Then, mix the purified carbon nanotubes with lithium manganate material and ball mill to obtain a composite material, in which the amount of carbon nanotubes added is 1% of the total amount of conductive agent.

[0019] Example 3 Preparation of positive electrode: LiMn2O4 / carbon nanotube: Super-P: KS-6: PVDF: NMP = 30:1:1:2:15; first dissolve PVDF in NMP and stir for 2h, then mix the LiMn2O4 / carbon nanotube composite material and the conductive agent and evenly disperse and stir them using a dry powder mixer, the spindle speed is 36r / min, and the stirring time is 80min. Then add the mixed materials to the glue and stir at high speed for 3h to disperse, the low-speed revolution speed is 20r / min, the high-speed dispersion speed is 2000r / min, and the vacuum degree is -0.1MPa. The stirred slurry is defoamed in vacuum and then sieved for coating, and the positive electrode sheet is obtained after drying, rolling and slitting.

[0020] Preparation of negative electrode: MCMB: Super-P: CMC: SBR: H2O = 47: 1: 0.75: 1.28: 60. First, dissolve CMC in deionized water and stir for 4 to 5 hours. Then mix the mesophase carbon microspheres and the conductive agent and evenly disperse and stir them using a dry powder mixer. The spindle speed is 30r / min and the stirring time is 45min. Then add the mixed materials to the glue and stir at high speed for 5 hours to disperse. The low-speed revolution speed is 28r / min, the high-speed dispersion speed is 2200r / min, and the vacuum degree is -0.1MPa. The stirred slurry is defoamed in vacuum and then sieved for coating. After drying, rolling and slitting, the negative electrode sheet is obtained.

[0021] The prepared positive and negative electrodes and separators are wound into cylindrical 18650 cells, which are then placed in shells and baked for 72 hours before being assembled and tested. The electrolyte uses a LiPF6 organic solvent system, and the separator uses a three-layer (PP / PE / PP) structure with a thickness of 20μm.

[0022] The positive and negative electrode powders are pre-mixed uniformly by using a dry powder mixer, the slurry stirring time is shortened, the problem of difficult uniform dispersion of powder materials is solved, and the consistency of the slurry is improved; the battery of the present invention has excellent room temperature cycle performance, a 0.5C discharge specific capacity of 118mAh / g, and a 1C cycle capacity retention rate of 80% for 1750 weeks.

[0023] Although the present invention has been described in detail by combining the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions shall be within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. Preparation method of lithium manganese oxide material, Its characteristics are: Preparation of lithium manganate material: Mix the manganese source and the lithium source in a molar ratio, sinter at high temperature in a box-type resistance furnace, and cool to room temperature to obtain the lithium manganate material; Among them, lithium carbonate 8-10 parts, manganese acetate 15-25 parts, iron acetate 2-5 parts, lead acetate 0.5-2 parts, nickel acetate 0.3-1.2 parts, citric acid 8-25 parts, deionized water 100-120 parts.

2. The method for preparing the lithium manganate material according to claim 1, Its characteristics are: Lithium carbonate and electrolytic manganese dioxide were mixed evenly in a molar ratio of 1:1.5, placed in a box-type resistance furnace and sintered at 700° C. for 12 hours under a nitrogen protective atmosphere, then cooled to room temperature, and the product was taken out and sieved to obtain a lithium manganate material.

3. The method for preparing the lithium manganate material according to claim 2, Its characteristics are: The high temperature sintering temperature is 600-800°C and the sintering time is 8-15h.

4. The method for preparing the lithium manganate material according to claim 3, Its characteristics are: Lithium carbonate and electrolytic manganese dioxide were mixed evenly in a molar ratio of 1:1.5, placed in a box-type resistance furnace and sintered at 700° C. for 12 hours under a nitrogen protective atmosphere, then cooled to room temperature, and the product was taken out and sieved to obtain a lithium manganate material.

5. The method for preparing a battery from the lithium manganese oxide material according to claim 1, Features: S1: Preparation of a composite material of lithium manganese oxide and carbon nanotubes, ball milling and mixing the chemically purified carbon nanotubes with the prepared lithium manganese oxide material to obtain a composite material of lithium manganese oxide and carbon nanotubes; S2: Positive electrode active material, negative electrode active material and conductive agent: The positive electrode active material is a composite material of lithium manganese oxide and carbon nanotubes, the conductive agent is a mixture of conductive carbon black and KS-6, the negative electrode active material is modified mesophase carbon microspheres, the conductive agent is conductive carbon black, and the slurry is made using a dry powder mixer and a high-speed stirrer; S3: Battery preparation: The positive electrode active material, the negative electrode active material and the conductive agent are slurried using a dry powder mixer and a high-speed stirrer.

6. The method for preparing a battery from the lithium manganese oxide material according to claim 5, Features: The positive electrode material of lithium manganate battery doped with Ni, Fe and Pb is prepared by the following method: lithium carbonate, manganese acetate, iron acetate, lead acetate, nickel acetate and citric acid are dissolved in deionized water in proportion, the pH is adjusted to 8 with ammonia water, heated in a water bath at 70-80°C until gel is formed, placed in a drying oven at 100°C for drying to obtain a dry gel, pretreated in an argon atmosphere at 400°C for 7-10h, calcined at 800-1000°C for 12-15h, cooled to room temperature, and ground to obtain the obtained material.

7. The method for preparing a battery from the lithium manganese oxide material according to claim 6, Features: The multi-walled carbon nanotubes are chemically purified before use.

8. Application of the lithium manganese oxide battery as claimed in claim 1 in the lithium battery industry.