阅读说明：本技术 一种改性的富锂锰基氧化物正极材料及其制备方法和应用 (Modified lithium-rich manganese-based oxide positive electrode material and preparation method and application thereof ) 是由 丁晓凯 林展 罗冬 崔佳祥 谢惠娴 于 2020-06-19 设计创作，主要内容包括：本发明提供了一种改性的富锂锰基氧化物正极材料及其制备方法和应用,所述改性的富锂锰基氧化物正极材料的结构由内到外依次包括富锂锰基氧化物正极材料、富含氧空位的原位诱导尖晶石结构层。本发明提供的制备方法简单易操作,能有效提高富锂锰基氧化物正极材料的循环稳定性,重复性好,适合大规模工业化生产。(The invention provides a modified lithium-rich manganese-based oxide positive electrode material and a preparation method and application thereof. The preparation method provided by the invention is simple and easy to operate, can effectively improve the cycling stability of the lithium-rich manganese-based oxide anode material, has good repeatability, and is suitable for large-scale industrial production.)

1. The modified lithium-rich manganese-based oxide cathode material is characterized by sequentially comprising a lithium-rich manganese-based oxide cathode material and an in-situ induced spinel structure layer rich in oxygen vacancies from inside to outside.

2. The modified lithium-rich manganese-based oxide composite positive electrode material as claimed in claim 1, wherein the molecular formula of the lithium-rich manganese-based oxide positive electrode material is Li_1+xTM_1-xO₂TM is at least two of Mn, Co, Ni, Fe, Cr, Ti, Mg and Al, and x is 0-0.4; preferably, the molecular formula of the lithium-rich manganese-based oxide cathode material is Li_1.2Mn_0.6Ni_0.2O₂。

3. The lithium-rich manganese-based oxide composite positive electrode material according to claim 1, wherein the particle size of the modified lithium-rich manganese-based oxide positive electrode material is 3 to 20 μm.

4. The preparation method of the modified lithium-rich manganese-based oxide cathode material as claimed in any one of claims 1 to 3, wherein the preparation method comprises the step of modifying the lithium-rich manganese-based oxide cathode material with an organic solvent to obtain the lithium-rich manganese-based oxide composite cathode material.

5. The method of manufacturing according to claim 4, comprising the steps of:

and (3) uniformly mixing the lithium-rich manganese-based oxide positive electrode material with an organic solvent, reacting under the protection of an inert atmosphere, cooling to room temperature, and cleaning, filtering and drying to obtain the modified lithium-rich manganese-based oxide positive electrode material.

6. The method according to claim 5, wherein the organic solvent is at least one of absolute ethanol, isopropanol, methanol, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, and ethyl methyl carbonate; preferably, the organic solvent is dimethyl carbonate.

7. The preparation method according to claim 5, wherein the weight-to-volume ratio of the lithium-rich manganese-based oxide positive electrode material to the organic solvent is 1 g: 5 mL-1 g: 50 mL; preferably, the weight volume ratio of the lithium-rich manganese-based oxide cathode material to the organic solvent is 1 g: 10 mL.

8. The method according to claim 5, wherein the reaction temperature is 100 to 200 ℃; the reaction time is 5-36 hours; preferably, the reaction temperature is 170 ℃; the reaction time was 26 hours.

9. The method according to claim 5, wherein the inert atmosphere is at least one of nitrogen, argon, helium; the cooling mode is natural cooling; the solvent used for cleaning is at least one of water and absolute ethyl alcohol; preferably, the inert atmosphere is high purity argon; the solvent used for cleaning is a mixed solvent of deionized water and absolute ethyl alcohol in a volume ratio of 1: 1.

10. Use of the modified lithium-rich manganese-based oxide positive electrode material according to any one of claims 1 to 3 as a positive electrode material in the preparation of lithium ion batteries or power batteries.

Technical Field

The invention particularly relates to a modified lithium-rich manganese-based oxide positive electrode material and a preparation method and application thereof.

Background

Along with the increasing approach of the period of prohibition of selling fuel vehicles in various countries around the world, the rapid popularization of new energy vehicles is accelerated, but the cost problem and the endurance problem of the new energy vehicles are rejected by users and other aspects all the time, and higher requirements are put forward on the energy density and the manufacturing cost of power batteries of the new energy vehicles. And in the cost constitution of the power battery, the positive electrode material occupies 40%, so the cost and the performance of the positive electrode material determine the cost performance of the power battery. Moreover, the positive electrode material is also a key factor which always restricts the energy density and power density of the power battery to be improved. Therefore, it is necessary to develop a positive electrode material having low cost and high energy density and power density.

Compared with the current commercialized anode materials (such as lithium manganate, lithium cobaltate, lithium iron phosphate, ternary anode materials and the like), the lithium-rich manganese-based oxide anode material has various advantages, such as low cost, no cobalt, low nickel and high theoretical specific capacity (more than 250mAh g)^-1) Wide working window (2.0-4.8V), and the like, and is considered to be the most promising anode material selected by the next generation of high energy density power lithium ion battery. However, the lithium-rich manganese-based oxide cathode material still has some defects at present, and the defects greatly limit the commercialization process of the lithium-rich manganese-based oxide cathode material. The lithium-rich manganese-based oxide cathode material is used as the cathode material of a lithium ion battery, and Li in the components is activated in the first activation process₂MnO₃When the phase is activated, a large amount of oxygen is released, so that lattice oxygen in a surface layer structure of the material is reduced, structural rearrangement is caused, and a diffusion channel of lithium ions is blocked; meanwhile, the high working voltage can promote the decomposition of the electrolyte to form substances such as hydrofluoric acid which are harmful to electrode materials, thereby causing the reduction of the performance of the power battery; moreover, during the subsequent circulation process, the surface layer structure of the lithium-rich manganese-based oxide cathode material can be damaged more seriously, so that the circulation stability of the material is reduced, and the commercialization requirement is difficult to meet. Currently, ion doping and morphology control can effectively improve the cycling stability of materials, but the ion doping and morphology control can effectively improve the cycling stability of materialsThe sub-doping introduces other impurity ions, and simultaneously, the processing cost of the material is increased, which is not beneficial to commercialization; the morphology control has high requirements on the preparation process of the material, the prepared morphology cannot be well preserved, the tap density of the material cannot be improved, and the commercialization cannot be realized. Meanwhile, the surface modification is a method for effectively improving the cycling stability of the lithium-rich manganese-based oxide cathode material.

Disclosure of Invention

In order to overcome the defects of the prior art and improve the cycling stability of the lithium-rich manganese-based oxide cathode material, the invention provides the modified lithium-rich manganese-based oxide cathode material and the preparation method and application thereof.

In order to realize the purpose, the technical scheme is as follows: the modified lithium-rich manganese-based oxide cathode material sequentially comprises a lithium-rich manganese-based oxide cathode material and an in-situ induced spinel structure layer rich in oxygen vacancies from inside to outside.

Preferably, the molecular formula of the lithium-rich manganese-based oxide cathode material is Li_1+xTM_1-xO₂TM is at least two of Mn, Co, Ni, Fe, Cr, Ti, Mg and Al, and x is 0-0.4; more preferably, the molecular formula of the lithium-rich manganese-based oxide cathode material is Li_1.2Mn_0.6Ni_0.2O₂。

Preferably, the particle size of the modified lithium-rich manganese-based oxide positive electrode material is 3-20 μm.

The invention provides a preparation method of the modified lithium-rich manganese-based oxide positive electrode material, which is characterized in that the lithium-rich manganese-based oxide positive electrode material is modified by an organic solvent to obtain the lithium-rich manganese-based oxide composite positive electrode material.

The preparation method provided by the invention is characterized in that the surface layer structure modification is carried out on the lithium-rich manganese-based oxide anode material by adopting an organic solvent to form the lithium-rich manganese-based oxide anode material/oxygen vacancy-rich in-situ induced spinel structure layer composite material. The spinel structure is mainly formed by coupling reaction between an organic solvent and the surface layer structure of the lithium-rich manganese-based oxide anode material, so that metal ions in the surface layer structure are partially dissolved out, and the surrounding metal ions are promoted to migrate to form the spinel structure; meanwhile, active oxygen in the surface layer structure is released, and partial vacancy is reserved to form oxygen vacancy. The oxygen vacancy-rich in-situ induced spinel structure layer can construct a three-dimensional lithium ion rapid transmission channel, and the diffusion rate of lithium ions is improved.

Preferably, the preparation method comprises the following steps:

and (3) uniformly mixing the lithium-rich manganese-based oxide positive electrode material with an organic solvent, reacting under the protection of an inert atmosphere, cooling to room temperature, and cleaning, filtering and drying to obtain the modified lithium-rich manganese-based oxide positive electrode material.

Preferably, the organic solvent is at least one of absolute ethyl alcohol, isopropanol, methanol, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate and ethyl methyl carbonate; more preferably, the organic solvent is dimethyl carbonate.

Preferably, the weight volume ratio of the lithium-rich manganese-based oxide cathode material to the organic solvent is 1 g: 5 mL-1 g: 50 mL; more preferably, the weight volume ratio of the lithium-rich manganese-based oxide cathode material to the organic solvent is 1 g: 10 mL.

Preferably, the reaction temperature is 100-200 ℃; the reaction time is 5-36 hours; more preferably, the reaction temperature is 170 ℃; the reaction time was 26 hours.

Preferably, the inert atmosphere is at least one of nitrogen, argon and helium; the cooling mode is natural cooling; the solvent used for cleaning is at least one of water and absolute ethyl alcohol; more preferably, the inert atmosphere is high purity argon; the solvent used for cleaning is a mixed solvent of deionized water and absolute ethyl alcohol in a volume ratio of 1: 1.

The invention also provides application of the modified lithium-rich manganese-based oxide positive electrode material as a positive electrode material in preparation of lithium ion batteries or power batteries.

Has the advantages that:

the invention provides a preparation method of a modified lithium-rich manganese-based oxide cathode material, which is characterized in that an organic solvent is adopted to modify the surface structure of the lithium-rich manganese-based oxide cathode material, and an in-situ induced spinel structure rich in oxygen vacancies is constructed on the surface layer of the material based on the coupling reaction between the organic solvent and the surface structure of the material, so that the diffusion rate of lithium ions is improved together; abundant oxygen vacancies can effectively inhibit the release of lattice oxygen and improve the structural stability of the surface layer of the material; the spinel structure can inhibit the conversion of the layered structure to the non-electrochemically active spinel structure in the circulation process, thereby improving the structural stability of the material.

Drawings

FIG. 1 shows X-ray diffraction patterns of materials obtained in examples 1 to 3 and comparative example 1.

FIG. 2 is a graph showing cycle performance of the materials obtained in examples 1 to 3 and comparative example 1.

FIG. 3 is a graph of the cycle performance of the materials obtained in examples 4 to 7.

Detailed Description

To better illustrate the objects, aspects and advantages of the present invention, the present invention will be further described with reference to specific examples.