阅读说明：本技术 一种低比表大粒径锰酸锂的制备方法 (Preparation method of lithium manganate with low specific surface area and large particle size ) 是由 钱飞鹏 赵春阳 李佳军 于 2020-12-29 设计创作，主要内容包括：本发明公开了一种低比表大粒径锰酸锂的制备方法,包括如下步骤：(1)将Li、M的混合后高速球磨,获得均匀混合物A；(2)将锂盐、锰盐溶于乙醇溶剂中,氨水调至溶胶状,得到锰酸锂溶胶B；(3)将混合物A、锰酸锂溶胶B及锰氧化物C混合搅拌混匀,喷雾干燥得到混合物D；(4)将混合物D高温烧结得到锰酸锂材料。本发明通过对Li及掺杂元素M的化合物细化处理,有利于后续分布的更均匀,细化处理后并与微米级锰氧化物及锰酸锂溶胶混合干燥后再高温煅烧,可以控制其平均颗粒尺寸在15～25μm,且晶粒完整,循环性能优异。(The invention discloses a preparation method of lithium manganate with low specific surface area and large particle size, which comprises the following steps: (1) mixing Li and M, and then carrying out high-speed ball milling to obtain a uniform mixture A; (2) dissolving lithium salt and manganese salt in an ethanol solvent, and adjusting ammonia water to be sol-like to obtain lithium manganate sol B; (3) mixing the mixture A, the lithium manganate sol B and the manganese oxide C, uniformly stirring, and spray-drying to obtain a mixture D; (4) and sintering the mixture D at high temperature to obtain the lithium manganate material. According to the invention, the compounds of Li and the doping element M are refined, so that the subsequent distribution is more uniform, the refined compounds are mixed with micron-sized manganese oxide and lithium manganate sol, dried and then calcined at high temperature, the average particle size of the refined compounds can be controlled to be 15-25 mu M, the crystal grains are complete, and the cycle performance is excellent.)

1. A preparation method of lithium manganate with low specific surface area and large particle size is characterized by comprising the following steps:

(1) mixing Li and a compound doped with an element M according to a certain chemical proportion, and then carrying out high-speed ball milling to obtain a uniform mixture A of Li and M;

(2) lithium salt and manganese salt are mixed according to the weight ratio of (1.05-1.20): (1.8-2.0) dissolving in an ethanol solvent according to the chemical ratio, and adjusting ammonia water to be sol-like to obtain lithium manganate sol B;

(3) mixing and stirring the uniform mixture A of Li and M, the lithium manganate sol B and the manganese oxide C uniformly, and spray-drying to obtain a mixture D;

(4) and sintering the mixture D at high temperature to obtain the lithium manganate material.

2. The method for preparing lithium manganate with low specific surface area according to claim 1, wherein in the step (1), the compound of Li and M is one or more of oxide, carbonate, nitrate and hydroxide.

3. The method for preparing lithium manganate with low specific surface area and large particle size according to claim 1, wherein in the step (1), the doping element M is manganese site doping, and M is any one or more of Al, Co, Cr, Y, Si, Mg, V, Zr, Ti, Sn, Mo, La, Ce, Pr, and Nd.

4. The method for producing lithium manganate having a low specific surface area and a large particle diameter according to any of claims 1 to 3, wherein in the step (1), the particle diameter of homogeneous mixture A is in the range of 100nm to 5 μm.

5. The method for preparing lithium manganate with low specific surface area according to claim 1, wherein in the step (2), the lithium salt and the manganese salt are a mixture of one or more of nitrate, acetate, oxalate, carbonate or hydroxide.

6. The method for preparing lithium manganate with low specific surface area and large particle size according to claim 1, wherein in the step (3), the lithium manganate sol B is added in a mass ratio of 5% to 40%.

7. The method for preparing lithium manganate having a low specific surface area and a large particle diameter according to claim 1, wherein in the step (3), the manganese oxide C is manganese dioxide or trimanganese tetroxide having a particle diameter in the range of 8 to 20 μm.

8. The method for producing lithium manganate having a low specific surface area according to claim 1, wherein in the step (3), the mixture of the homogeneous mixture a, the lithium manganate sol B and the manganese oxide C is spray-dried at 80 to 120 ℃.

9. The method for producing lithium manganate with low specific surface area and large particle size according to claim 1, wherein the ratio a of the doping element M is in the range of 0 < a.ltoreq.0.2M, where M is the ratio of the substituted element sites.

Technical Field

The invention belongs to the technical field of lithium ion battery anode materials, and relates to a preparation method of lithium manganate with low specific surface area and large particle size.

Background

Currently, commonly used anode materials are lithium cobaltate, lithium manganate, lithium nickel cobalt manganese, lithium iron phosphate and the like. Because cobalt is expensive, and lithium cobaltate and lithium nickel cobalt manganese oxide have great potential safety hazards when used for power batteries. Lithium manganate and lithium iron phosphate are ideal anode materials of the lithium ion power battery. Although the lithium manganate material has low cost and good safety performance, the specific capacity is relatively low, and the cycle life, particularly the high-temperature cycle performance is not ideal due to the dissolution of Mn, Jahn-Teller distortion effect and unstable crystal lattice.

In order to further improve the cycle performance of the lithium manganate, researches show that the lithium manganate material with large particle size and low specific surface area is obtained by controlling the morphology, and the high-temperature cycle performance of the lithium manganate can be obviously improved. The lithium manganate material with large particle size has low specific surface area, reduces the contact area between the material and the electrolyte, can reduce the dissolution of manganese in the electrolyte, improves the stability of the product in the electrolyte, effectively improves the cycle performance of the battery, has high stacking density with large particle size, and can effectively improve the energy density of the lithium manganate.

Disclosure of Invention

The invention aims to solve the technical problem of overcoming the defect of unsatisfactory cycle performance of lithium manganate at high temperature in the prior art and provides a preparation method of lithium manganate with low specific surface area and large particle size.

In order to solve the technical problems, the invention provides the following technical scheme:

a preparation method of lithium manganate with low specific surface area and large particle size comprises the following steps:

(1) mixing Li and a compound doped with an element M according to a certain chemical proportion, and then carrying out high-speed ball milling to obtain a uniform mixture A of Li and M;

(2) dissolving lithium salt and manganese salt in an ethanol solvent according to the chemical ratio of (1.05-1.20) to (1.8-2.0), and adjusting ammonia water to be sol-like to obtain lithium manganate sol B;

(3) mixing and stirring the uniform mixture A of Li and M, the lithium manganate sol B and the manganese oxide C uniformly, and spray-drying to obtain a mixture D;

(4) and sintering the mixture D at high temperature to obtain the lithium manganate material.

Preferably, in the step (1), the compound of Li and M is one or more of oxide, carbonate, nitrate, or hydroxide.

Preferably, in the step (1), the doping element M is manganese-site doped and is one or more of Al, Co, Cr, Y, Si, Mg, V, Zr, Ti, Sn, Mo, La, Ce, Pr, and Nd.

Preferably, in the step (1), the particle size of the homogeneous mixture A is in the range of 100nm to 5 μm.

Preferably, in the step (2), the lithium salt and the manganese salt are one or more of nitrate, acetate, oxalate, carbonate and hydroxide.

Preferably, in the step (3), the proportion of the added lithium manganate sol B is 5-40%.

Preferably, in the step (3), the manganese oxide C is manganese dioxide or trimanganese tetroxide with a particle size of 8-20 μm.

Preferably, in the step (3), the mixture of the uniform mixture A, the lithium manganate sol B and the manganese oxide C is dried by spray drying at 80-120 ℃.

Preferably, the proportion a of the doping element M is in the range of 0 < a ≦ 0.2M, wherein M is the proportion of the substituted element site.

Has the advantages that:

according to the invention, the compounds of Li and the doping element M are refined, so that the subsequent distribution is more uniform, the refined compounds are mixed with micron-sized manganese oxide and lithium manganate sol, dried and then calcined at high temperature, the average particle size of the refined compounds can be controlled to be 15-25 mu M, the crystal grains are complete, and the cycle performance is excellent. The lithium manganate with large particle size has low specific surface area, reduces the contact area between the material and the electrolyte, can reduce the dissolution of manganese in the electrolyte, improves the stability of the product in electrolysis, and effectively improves the cycle performance of the battery. In addition, the large-particle-size lithium manganate has high bulk density, and can provide a lithium battery having high energy density.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

fig. 1, SEM image of lithium manganate in example 1;

FIG. 2 is a particle size distribution diagram of lithium manganate in example 1;

FIG. 3 is a high temperature (55 ℃ C.) 1C cycle curve of lithium manganate in example 1.

Detailed Description

The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.

Example 1

The synthesis of low-specific-area large-particle-size lithium manganate Li1.12Mn1.88Al0.12O4 comprises the following steps:

weighing battery-grade lithium carbonate and nano-alumina (the chemical proportion is a known proportion and is omitted here) in a certain chemical proportion, taking deionized water as a grinding aid, taking zirconia balls as a ball-milling medium, and performing high-speed ball milling for 10 hours by using a horizontal ball mill, wherein the ball-material ratio is 8:1 and the solid content is 70%, so as to obtain a uniform mixture with the particle size D50 of about 600 nm. Respectively weighing lithium hydroxide and manganese nitrate according to the metering ratio of 1.12:1.88, dissolving in an ethanol solvent, and then adjusting the pH value to be sol by using ammonia water to obtain the lithium manganate sol. Adding 25% of lithium manganate sol and 18-micron manganese dioxide D50 into the uniform mixture, opening a horizontal ball mill to perform high-speed ball milling for 1 hour, and performing spray drying on the slurry at 100 ℃. And (3) calcining the dried mixture at 820 ℃ for 15h to obtain the required low-specific-surface-area large-particle-size lithium manganate Li1.12Mn1.88Al0.12O4. The SEM picture is shown in figure 1, and the particle size distribution of lithium manganate is shown in figure 2.

The obtained material is used for electrical property test, the 0.2C specific discharge capacity is 112mAh/g, the capacity retention rate of 100 cycles at normal temperature and 1C is more than 98%, the capacity retention rate of 100 cycles at high temperature and 55 ℃ and 1C is more than 96.5%, the granularity D50 is 23 μm, and the specific surface area is 0.25 square meter/g. The high temperature (55 ℃ C.) 1C cycle curve of lithium manganate is shown in FIG. 3.

Example 2:

the synthesis of low-specific-area large-particle-size lithium manganate Li1.16Mn1.94Co0.03Y0.03O4 comprises the following steps:

weighing battery-grade lithium carbonate, nanoscale cobaltous oxide and nanoscale yttrium oxide (the chemical proportion is a known proportion and is omitted here) in a certain chemical proportion, taking ethanol as a grinding aid, zirconium oxide as a ball-milling medium, the ball-material ratio is 5:1, the solid content is 55%, and performing high-speed ball milling for 8 hours by using a horizontal ball mill to obtain a uniform mixture with the particle size D50 of about 900 nm. Respectively weighing lithium hydroxide and manganese nitrate according to the metering ratio of 1.16:1.94, dissolving in an ethanol solvent, and then adjusting the pH value to be sol by using ammonia water to obtain the lithium manganate sol. Adding 35% of lithium manganate sol and trimanganese tetroxide with the D50 of 10 mu m into the uniform mixture, opening a horizontal ball mill to perform high-speed ball milling for 2 hours, and then dynamically drying the slurry at 85 ℃. And (3) calcining the dried mixture at 880 ℃ for 15h to obtain the required low-specific-surface-area large-particle-size lithium manganate Li1.11Mn1.94Co0.03Y0.03O4. The obtained material is used for electrical property test, the 0.2C specific discharge capacity is 106mAh/g, the capacity retention rate of 100 cycles at normal temperature and 1C is more than 99%, the capacity retention rate of 100 cycles at high temperature and 55 ℃ and 1C is more than 97%, the granularity D50 is 19 μm, and the specific surface area is 0.32 square meter/g.

Example 3:

the synthesis of the low-specific-surface large-particle-size lithium manganate Li1.08Mn1.95Mg0.04Nb0.01O4 comprises the following steps:

weighing battery-grade lithium carbonate, micron magnesium hydroxide and micron niobium hydroxide (the chemical proportion is a known proportion and is omitted here) in a certain chemical proportion, adopting deionization as a grinding aid, zirconium oxide as a ball-milling medium, the ball-material ratio is 10:1, the solid content is 70%, and performing high-speed ball milling by using a horizontal ball mill to obtain a uniform mixture with the particle size D50 of about 3 microns. Respectively weighing lithium hydroxide and manganese nitrate according to the metering ratio of 1.08:1.96, dissolving in an ethanol solvent, and then adjusting the pH value to be sol by using ammonia water to obtain the lithium manganate sol. 10% of lithium manganate sol and 15 mu m manganese dioxide D50 were added to the above homogeneous mixture, and after opening the horizontal ball mill and high-speed ball milling for 1 hour, the slurry was spray-dried at 105 ℃. And (3) calcining the dried mixture at the temperature of 790 ℃ for 18h to obtain the required low-specific-surface-area large-particle-size lithium manganate Li1.08Mn1.95Mg0.04Nb0.01O4. The obtained material is used for electrical property test, the 0.2C specific discharge capacity is 123mAh/g, the capacity retention rate of 100 cycles at normal temperature and 1C is more than 96%, the capacity retention rate of 100 cycles at high temperature and 55 ℃ and 1C is more than 93%, the granularity D50 is 21 μm, and the specific surface area is 0.29 square meters per gram.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.