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Alkaline-earth metal silicide preparation method

A technology of alkaline earth metals and silicides, applied in structural parts, electrical components, battery electrodes, etc., can solve the problems of Mg or Ca volatilization and loss of Si, poor product phase uniformity, and low product purity, and achieve easy operation, low cost, The effect of high purity

Inactive Publication Date: 2012-11-07
ZHEJIANG UNIV
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  • Claims
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AI Technical Summary

Problems solved by technology

[0006] At present, there are three main methods for the preparation of alkaline earth metal silicides: smelting, mechanical alloying and powder metallurgy. Higher smelting temperature will lead to volatilization loss of Mg or Ca and carbonization of Si, resulting in poor phase homogeneity of the product and coarse grains; secondly, in the mechanical alloying method, impurity phases such as Fe are easily introduced by ball milling for a long time, and the purity of the resulting product is low; Thirdly, the powder metallurgy method also faces the problem of sample oxidation and carbonization due to the high temperature and long holding time in the preparation process.

Method used

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  • Alkaline-earth metal silicide preparation method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] In a glove box with an argon atmosphere, weigh MgH at a molar ratio of 2:1 2 and Si samples, put them into a ball mill jar, the ball-to-material ratio is 60:1, and the grinding balls are stainless steel balls, which will contain MgH 2 Put the ball mill jar of the mixture with Si on the planetary ball mill, and ball mill it at a speed of 300 rpm for 8 hours to obtain 2MgH 2 -Si mixture. 2MgH 2 -Si mixture is heated in vacuum to dehydrogenate, the heating rate is 2 degrees Celsius / min, after heating to 400 degrees Celsius, heat preservation for 4 hours and vacuumize the system, then furnace cooling to room temperature, the resulting sample from argon The atmosphere of the glove box was taken out to obtain Mg 2 Si sample.

[0029] figure 1 2MgH after ball milling 2 -The hydrogen desorption curve of the Si mixture varies with temperature. It can be seen from the figure that the initial temperature of the dehydrogenation reaction is around 200 degrees Celsius, and the ...

Embodiment 2

[0031] In a glove box with an argon atmosphere, weigh MgH at a molar ratio of 2:1 2 and Si samples, put them into a ball mill jar, the ball-to-material ratio is 90:1, and the balls are zirconia balls, which will contain MgH 2 Put the ball mill jar of the mixture with Si on the planetary ball mill, and ball mill for 4 hours at a speed of 400 rpm to obtain 2MgH 2 -Si mixture. 2MgH 2 -Si mixture is heated in vacuum to dehydrogenate, the heating rate is 10 degrees centigrade / minute, after heating to 400 degrees centigrade, keep warm for 4 hours and vacuumize the system, then furnace cool down to room temperature, and the obtained sample is decomposed from argon The atmosphere of the glove box was taken out to obtain Mg 2 Si sample.

[0032] figure 2 2MgH 2 The XRD pattern (X-ray diffraction pattern) of the product after the Si mixture is heated to release hydrogen, as can be seen from the figure, the hydrogen release product is Mg of the Fm-3m space group 2 Si crystal, the...

Embodiment 3

[0034] In a glove box with an argon atmosphere, weigh MgH at a molar ratio of 2:1 2 and Si samples, put them into a ball mill jar, the ball-to-material ratio is 120:1, and the grinding balls are stainless steel balls, which will contain MgH 2 Put the ball mill jar of the mixture with Si on the planetary ball mill, and ball mill for 2 hours at a speed of 600 rpm to obtain 2MgH 2 -Si mixture. 2MgH 2 -Si mixture is heated in vacuum to dehydrogenate, the heating rate is 10 degrees centigrade / minute, after heating to 400 degrees centigrade, keep warm for 4 hours and vacuumize the system, then furnace cool down to room temperature, and the obtained sample is decomposed from argon The atmosphere of the glove box was taken out to obtain Mg 2 Si sample.

[0035] image 3 2MgH 2 The scanning electron micrograph of the product after the Si mixture is heated to dehydrogenate, the scanning electron micrograph shows that the particles are submicron in size and flocculent after agglome...

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Abstract

The invention discloses an alkaline-earth metal silicide preparation method. The preparation method comprises the following steps: achieving ball-milling mixing of alkaline-earth metal hydride and silicon, heating the obtained mixture in a vacuum or inert gas atmosphere to release hydrogen, and then cooling to the room temperature to obtain the alkaline-earth metal silicide. The alkaline-earth metal silicide preparation method has the advantages of simple process, easiness in operation, lower cost, low energy consumption and no environmental pollution; hydrogen used in the method can be recycled, so that the cost is saved; the alkaline-earth metal silicide obtained by adopting the method has high productivity, high purity and good phase homogeneous degree; and when serving as the anode material of a lithium ion secondary battery, the alkaline-earth metal silicide has high coulombic efficiency and good charge-discharge circulating stability.

Description

technical field [0001] The invention relates to a negative electrode material of a lithium ion secondary battery, in particular to a preparation method of an alkaline earth metal silicide. Background technique [0002] With the rapid development of human society, environmental and energy issues have become increasingly prominent. In order to realize the sustainable development of human society, it is necessary to develop new efficient and clean energy conversion, storage and utilization methods. [0003] Due to the advantages of high working potential, high specific energy density, high specific power, wide operating temperature range, long cycle life and environmental friendliness, lithium-ion batteries are widely used in portable mobile electronic equipment, power tools, energy storage devices, electric vehicles and Hybrid vehicles are widely used. However, with the miniaturization and weight reduction of electronic equipment, the requirements for lithium-ion secondary ba...

Claims

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Application Information

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IPC IPC(8): H01M4/38
CPCY02E60/12Y02E60/10
Inventor 刘永锋贺燕萍潘洪革马瑞军高明霞
Owner ZHEJIANG UNIV
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