Method for constructing spinel structure on surface layer of lithium-rich manganese-based positive electrode material

A spinel structure and positive electrode material technology, applied in the direction of positive electrodes, structural parts, chemical instruments and methods, etc., can solve the problems of low Coulombic efficiency, achieve the effects of simple regulation, easy expansion of production, and improved rate performance

Active Publication Date: 2017-09-29
BEIJING INSTITUTE OF TECHNOLOGYGY
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  • Application Information

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Problems solved by technology

[0005] In view of the fact that there is no cheap, efficient and seamless method for preparing a cladding layer with a spinel structure in the prior art, the purpose of the present invention is to provide a surface layer structure on the lithium-rich manganese-based positive electrode material. The method of spinel structure, which not only ensures the smooth flow of lithium ion transmission channels by transforming the surface structure of the bulk material into a spinel structure, but also prevents the surface layer of spinel structure from causing the material to be damaged during the charge-discharge cycle due to structural stress. Falling off solves the problem of low Coulombic efficiency of lithium-rich manganese-based cathode materials in the first week, and improves the structural stability of electrode materials in repeated charge-discharge cycles

Method used

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  • Method for constructing spinel structure on surface layer of lithium-rich manganese-based positive electrode material
  • Method for constructing spinel structure on surface layer of lithium-rich manganese-based positive electrode material
  • Method for constructing spinel structure on surface layer of lithium-rich manganese-based positive electrode material

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Effect test

Embodiment 1

[0035] After adding 5g of lithium-rich manganese-based positive electrode material to 100mL aqueous solution of ammonium dihydrogen phosphate with a concentration of 0.25mol / L, magnetic stirring is performed to make the electrode material generate Li in the acidic solution. + —H +Ion exchange, and measure the pH value of the ammonium dihydrogen phosphate aqueous solution with a pH meter until the change rate of the pH value is less than 0.01min -1 , carry out vacuum filtration, and wash the solid obtained by suction filtration with deionized water for 3 times, and then dry in an oven at 80°C for 6h; then place the dried solid in a muffle furnace, and sinter at 450°C for 5h Transform the lithium-deficient structure of the surface layer into a spinel structure, and cool with the furnace to obtain a lithium-rich manganese-based positive electrode material with a spinel structure on the surface.

[0036] figure 1 It is the XRD comparison chart of the modified lithium-rich mangan...

Embodiment 2

[0040] After adding 5g of lithium-rich manganese-based positive electrode material to 100mL aqueous solution of ammonium dihydrogen phosphate with a concentration of 0.25mol / L, magnetic stirring is performed to make the electrode material generate Li in the acidic solution. + —H + Ion exchange, and measure the pH value of the ammonium dihydrogen phosphate aqueous solution with a pH meter until the change rate of the pH value is less than 0.01min -1 , carry out vacuum filtration, and wash the solid obtained by suction filtration with deionized water for 3 times, and then dry in an oven at 80°C for 6h; then place the dried solid in a muffle furnace, and sinter at 300°C for 5h Transform the lithium-deficient structure of the surface layer into a spinel structure, and cool with the furnace to obtain a lithium-rich manganese-based positive electrode material with a spinel structure on the surface.

[0041] Compared with the XRD pattern of the original lithium-rich manganese-based ...

Embodiment 3

[0045] After adding 5g of lithium-rich manganese-based positive electrode material to 100mL aqueous solution of ammonium dihydrogen phosphate with a concentration of 0.25mol / L, magnetic stirring is performed to make the electrode material generate Li in the acidic solution. + —H + Ion exchange, and measure the pH value of the ammonium dihydrogen phosphate aqueous solution with a pH meter until the change rate of the pH value is less than 0.01min -1 , carry out vacuum filtration, and wash the solid obtained by suction filtration with deionized water for 3 times, and then dry in an oven at 80°C for 6h; then place the dried solid in a muffle furnace, and sinter at 600°C for 5h Transform the lithium-deficient structure of the surface layer into a spinel structure, and cool with the furnace to obtain a lithium-rich manganese-based positive electrode material with a spinel structure on the surface.

[0046] Compared with the XRD pattern of the original lithium-rich manganese-based ...

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Abstract

The invention relates to a method for constructing a spinel structure on a surface layer of a lithium-rich manganese-based positive electrode material and belongs to the field of chemical energy storage batteries. The method comprises the following steps: adding the lithium-rich manganese-based positive electrode material into a weakly acidic aqueous solution, and performing Li+ and H+ ion exchange; and performing heat treatment on the positive electrode material subjected to the ion exchange to enable the surface lithium-poor structure to be changed into the spinel structure, thereby obtaining the lithium-rich manganese-based positive electrode material with the spinel structure on the surface layer. According to the method disclosed by the invention, the surface structure of the body material is changed into the spinel structure, so that a lithium-ion transport channel is kept smooth, the rate capability of the lithium-rich manganese-based positive electrode material is improved, and the first-cycle coulombic efficiency is improved. In addition, according to the method disclosed by the invention, the depth of the constructed spinel layer can be effectively regulated by regulating the concentration and treatment time of weak acid, so that the electrochemical performance of the electrode material is adjusted. The control manner is simple and feasible, the reaction time does not need to be strictly controlled, and the reproducibility and reliability are high.

Description

technical field [0001] The invention relates to a preparation method of a lithium-rich manganese-based positive electrode material, in particular to a method for constructing a spinel structure on the surface layer of a lithium-rich manganese-based positive electrode material, belonging to the field of chemical energy storage batteries. Background technique [0002] On the one hand, the rapid development of mobile electronic devices urgently requires the development of lithium secondary batteries with higher capacity; on the other hand, previous energy crises and severe environmental problems have forced governments to intensify efforts to promote the development of new energy electric vehicle industries, and The rapid development of electric vehicles also depends on lithium secondary batteries with higher capacity and faster charge and discharge rates. To meet this demand, it is first necessary to develop a new generation of high-capacity electrode materials. At present, l...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01G45/12H01M4/36H01M4/505H01M10/0525
CPCC01G45/1242C01G45/1257C01P2002/20C01P2002/32C01P2002/72C01P2004/04C01P2004/80C01P2006/40H01M4/366H01M4/505H01M10/0525H01M2004/028Y02E60/10
Inventor 苏岳锋郑玉陈实陈来卢赟王敬包丽颖吴锋
Owner BEIJING INSTITUTE OF TECHNOLOGYGY
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