Negative electrode material for nonaqueous electrolyte secondary battery, making method and lithium ion secondary battery

A non-aqueous electrolyte and secondary battery technology, applied in non-aqueous electrolyte battery electrodes, non-aqueous electrolytes, secondary batteries, etc., can solve the problems of low charging/discharging efficiency in the first cycle, and achieve high-cycle charging/discharging Efficiency, Ease of Method, Simple Method Effect

Inactive Publication Date: 2010-09-29
SHIN ETSU CHEM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0017] The present inventors have attempted to find a silicon-based active material for a negative electrode of a nonaqueous electrolyte secondary battery, which has a high battery capacity exceeding that of a carbonaceous material, minimizes the variation in volume expansion inherent in a silicon-based negative electrode active material, and overcomes Disadvantage of silicon oxide's 1st cycle charge / discharge efficiency is low

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0051] In an argon flow, 100 g of particles with an average particle size of 5 μm and a BET specific surface area of ​​3.5 m 2 / g of SiOx (x=1.01) particles were heat-treated at 1000°C for 3 hours. When observed under a transmission electron microscope (TEM), the heat-treated particles were found to have a structure in which silicon nanoparticles were dispersed in silicon oxide.

[0052] At room temperature, the heat-treated powder was filled into a 2-liter plastic bottle, where it was wetted with 30 mL of methanol, after which 200 mL of deionized water was added. After the entire powder was infiltrated to contact with deionized water, 5 mL of 50% by weight aqueous hydrofluoric acid was added slowly and stirred. The resulting mixture had a hydrofluoric acid concentration of 1.1% by weight or contained 2.5 g of hydrogen fluoride per 100 g of heat-treated powder. The mixture was kept at room temperature for 1 hour for etching.

[0053] After the etching process, rinse with de...

Embodiment 2

[0061] As in Example 1, the same heat-treated particles as in Example 1 were subjected to etching treatment except that the amount of a 50% by weight hydrofluoric acid aqueous solution was changed from 5 mL to 57.5 mL (the resulting mixture had 10% by weight of hydrogen Fluoric acid concentration or relative to 100g heat-treated powder contains 28.75g hydrogen fluoride). 90.6 g of black particles were recovered. The black particles had an oxygen concentration of 29.4% by weight before carbon coating, indicating an oxygen / silicon molar ratio of 0.73. The black particles (after carbon coating) have an average particle size of 5.1 μm and 18.8 m 2 / g of the BET specific surface area and is conductive because the carbon coverage is 4.9% by weight based on the black particles. When observed under TEM, the black particles were found to have a structure in which silicon nanoparticles were dispersed in silicon oxide and had a size of 5 nm.

[0062] As in Example 1, negative electrod...

Embodiment 3

[0064] At room temperature, 100 g of heat-treated powder as in Example 1 were charged into a stainless steel chamber. Hydrofluoric acid gas diluted to 30% by volume with nitrogen was passed through the chamber for 1 hour. After the flow of hydrofluoric acid was interrupted, the chamber was purged with nitrogen until the HF concentration in the exhaust gas as monitored by the FT-IR monitor decreased to less than 5 ppm. Subsequently, the pellets were taken out, the pellets had a weight of 94.5 g and an oxygen concentration of 33.4% by weight, indicating an oxygen / silicon molar ratio of 0.88.

[0065] The particles were coated with carbon as in Example 1 and 105.5 g of black particles were recovered. The black particles have an average particle size of 5.3 μm, 6.3m 2 / g of the BET specific surface area, and the carbon coverage based on the black particles was 5.2% by weight. When observed under TEM, the black particles were found to have a structure in which silicon nanopartic...

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Abstract

A negative electrode material comprising composite particles having silicon nano-particles dispersed in silicon oxide is suited for use in nonaqueous electrolyte secondary batteries. The silicon nano-particles have a size of 1-100 nm. The composite particles contain oxygen and silicon in a molar ratio: 0<O / Si<1.0. Using the negative electrode material, a lithium ion secondary battery can be fabricated which features high 1st cycle charge / discharge efficiency, capacity, and cycle performance. The invention also relates to a method for making the negative electrode material.

Description

technical field [0001] The present invention generally relates to nonaqueous electrolyte secondary batteries, typically lithium ion secondary batteries. In particular, the present invention relates to a negative electrode material used in such batteries, and more particularly to a negative electrode material and a preparation method thereof having the advantage that when the negative electrode material is used as a negative electrode in a lithium-ion secondary battery Active materials have high first-cycle charge / discharge efficiency, capacity, and cycle performance. Background technique [0002] With the rapid progress of portable electronic devices and communication equipment in recent years, non-aqueous electrolyte secondary batteries having high energy density are highly demanded in terms of cost, size and weight reduction. Many measures for increasing the capacity of such nonaqueous electrolyte secondary batteries are known in the art. For example, JP 3008228 and JP 3...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/13H01M4/38H01M10/0525
CPCY02E60/122H01M2004/021H01M4/485H01M10/0525Y02E60/10Y02E60/50B82Y30/00H01M4/38H01M4/405H01M4/48H01M2250/30H01M2300/0017Y02P70/50
Inventor 渡边浩一朗樫田周福冈宏文
Owner SHIN ETSU CHEM CO LTD
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