Lithium ion secondary battery composite positive material and preparation method thereof

A composite positive electrode material and secondary battery technology, which is applied to battery electrodes, non-aqueous electrolyte battery electrodes, circuits, etc., can solve problems such as structural damage, rapid capacity decay, and loss of the meaning of coating, and achieve effective coating and good Electronic conductance and mechanical strength, and the effect of suppressing side reactions at the interface

Active Publication Date: 2015-06-03
QINGHAI TAIFENG XIANXING LITHIUM ENERGY TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the above preparation method, there is carbon thermal reduction of the organic matter on the surface of the positive electrode active material under a high-temperature inert atmosphere or a protective atmosphere, causing structural damage, causing rapid capacity decay, and losing the meaning of coating

Method used

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  • Lithium ion secondary battery composite positive material and preparation method thereof
  • Lithium ion secondary battery composite positive material and preparation method thereof
  • Lithium ion secondary battery composite positive material and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] Lithium cobalt oxide (LiCoO 2 ) SEM image before coating as image 3 (a) shown.

[0033] Add 1.0g of polyacrylonitrile powder to 80ml of N,N-dimethylformamide, heat and stir in an oil bath at 60°C until a transparent solution is formed, then add 100g of lithium cobaltate to the above solution, and place in an oil bath at 150°C Stirring was continued and the solvent was evaporated to dryness. The powder obtained after evaporating the solvent was placed in a muffle furnace for treatment at 400°C / 0.5h, the heating rate was 5°C / min, and the treatment atmosphere was air (the volume fraction of oxygen was about 25%).

[0034] Lithium cobaltate (LiCoO 2 ) after coating SEM as attached image 3 (b) shown.

[0035] The UV-Vis absorption spectrum of the polyacrylonitrile coating after being treated at different temperatures (250°C and 400°C) for 0.5h, as shown in Figure 4 As shown, the variation of the absorption peak with different temperatures in the figure indicates the...

Embodiment 2

[0038]Add 1.0g of polyacrylonitrile powder to 80ml of N,N-dimethylformamide, heat and stir in an oil bath at 60°C until a transparent solution is formed, then add 100g of lithium cobaltate to the above solution and continue to stir to form a uniform suspension. The above suspension was spray dried to remove N,N dimethylformamide. The powder obtained after spray drying was placed in a muffle furnace for treatment at 400 °C / 0.5 h, the heating rate was 5 °C / min, and the treatment atmosphere was air. Using N-methylpyrrolidone as a solvent, stir the powder obtained after sintering with conductive carbon black and polyvinylidene fluoride according to the mass ratio of 90:5:5, and then coat it on the surface of clean aluminum foil, and scrape it to form a film. After blast drying, the electrode sheets were punched into discs with a diameter of 8 mm, and further dried in a vacuum oven at 120° C. for 6 hours to remove moisture. Use the prepared electrode sheet as the working electrode...

Embodiment 3-5

[0040] In the same manner as in Example 1, the lithium cobaltate was replaced by lithium nickelate, lithium manganate, and lithium nickel-cobalt manganate in turn, and the prepared electrode sheet was used as the working electrode of the half-cell, and lithium metal was used as the counter electrode. / L LiPF 6 / Ethylene carbonate (EC)-dimethyl carbonate (DMC) (mass ratio of EC and DMC 1:1) is used as electrolyte, is assembled into battery in glove box and carries out charge and discharge test to its battery, and the voltage range is 3.0-4.5V, charge and discharge current density is 0.2C.

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Abstract

The invention discloses a lithium ion secondary battery composite positive material and a preparation method thereof. The lithium ion secondary battery composite positive material is a high-performance composite material which is formed by coating the lithium ion secondary battery composite positive material with cross-linkable polymer under a non-inert atmosphere. The cross-linkable polymer and the positive material liquid phase are uniformly mixed, dried and processed at a high temperature under the non-inert atmosphere, so that the polymer is cross-linked and cyclized, and the coating of the positive material is completed, damages of organic substances to carbon thermal reduction of the positive material under a high-temperature inert atmosphere are avoided; the cross-linked and cyclized coating layer has electronic conductivity and mechanical strength, is uniformly coated, effectively prevents direct contact of active particles and the electrolyte, so that the problems of low side reaction and circulating efficiency of electrolyte and the active material particles, quick capacity attenuation, and the like are solved. Moreover, according to the preparation method, the preparation process is simple, the cost is low and the preparation method is suitable for large-scale production.

Description

technical field [0001] The invention belongs to the technical field of batteries, and in particular relates to a lithium-ion secondary battery composite cathode material and a preparation method thereof. Background technique [0002] As a rechargeable secondary battery, lithium-ion batteries have been widely used in digital electronic products such as notebooks and mobile phones due to their advantages such as high energy density, small self-discharge, and long cycle life. However, with the rapid development of digital electronic products, it is becoming more and more urgent for people to further increase the capacity of lithium-ion batteries. While developing cathode materials with higher capacity, increasing the charging voltage of existing cathode materials is an effective means to increase the energy density of lithium-ion batteries. Lithium cobalt oxide is currently the most commonly used cathode material for commercial lithium-ion batteries, and its theoretical capaci...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/13H01M4/139H01M4/62
CPCH01M4/62H01M4/628Y02E60/10
Inventor 申兰耀徐世国武斌李淼张继泉周恒辉杨新河
Owner QINGHAI TAIFENG XIANXING LITHIUM ENERGY TECH CO LTD
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