Power storage device and method of manufacturing the same

A technology of electric storage device and manufacturing method, which is applied in the direction of electrolyte storage battery manufacturing, final product manufacturing, non-aqueous electrolyte storage battery, etc., and can solve problems such as poor conductivity

Active Publication Date: 2012-12-05
SEMICON ENERGY LAB CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In addition, in the portion where the density of the alloy-based negative electrode material particles is high, there is a portion without the conductive additive, and the conductivity of this portion is poor, resulting in the generation of alloy-based negative electrode material particles that cannot contribute to the increase in capacity.

Method used

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  • Power storage device and method of manufacturing the same
  • Power storage device and method of manufacturing the same
  • Power storage device and method of manufacturing the same

Examples

Experimental program
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Embodiment approach 1

[0094] In this embodiment, an example in which silicon is used as an alloy-based negative electrode material and a carbon film composed of 1 to 50 graphene layers is formed on the surface of silicon particles will be described. First, graphite oxide is produced by oxidizing graphite, and ultrasonic vibration is applied to the graphite oxide to obtain graphene oxide. For details, refer to Patent Document 2. In addition, commercially available graphene oxide can also be used. In order to obtain graphene oxide from graphite, the following steps are preferably performed.

[0095] First, graphite oxide such as flaky graphite is oxidized to obtain graphite oxide. Graphite oxide is formed when some parts of graphite are oxidized and combined with functional groups such as carbonyl, carboxyl, and hydroxyl groups. The crystallinity of graphite is destroyed, and the distance between graphenes becomes larger. Therefore, separation between layers is likely to occur by ultrasonic treatm...

Embodiment approach 2

[0122] In this embodiment, an example in which a carbon film composed of 1 to 50 graphene layers is formed on the surface of a silicon active material layer formed on a current collector will be described. First, graphene oxide is dispersed in a solvent such as water or NMP. The solvent is preferably a polar solvent. The concentration of graphene oxide can be set at 0.1 g to 10 g per 1 L.

[0123] The entire current collector including the silicon active material layer was immersed in the above solution, pulled out, and then dried. In addition, a layer made of a highly conductive material such as copper may be formed in advance on the surface of the silicon active material layer. In addition, heating is performed at a temperature of 150° C. or higher, preferably 200° C. or higher, in a reducing atmosphere such as vacuum or an inert gas (nitrogen or a rare gas, etc.). Through the above steps, a carbon film composed of 1 to 50 graphene layers can be formed on the surface of t...

Embodiment approach 3

[0127] In this embodiment, another example in which a carbon film composed of 1 to 50 graphene layers is formed on the surface of a silicon active material layer formed on a current collector will be described. Similar to Embodiment 2, graphene oxide is dispersed in a solvent such as water or NMP. The concentration of graphene oxide can be set at 0.1 g to 10 g per 1 L.

[0128] The current collector formed with the silicon active material layer was placed in a solution in which graphene oxide was dispersed to use it as a positive electrode. In addition, a layer made of a highly conductive material such as copper may be formed in advance on the surface of the silicon active material layer. In addition, put the conductor that becomes the negative electrode in the solution, and apply an appropriate voltage (such as 5V to 20V) between the positive electrode and the negative electrode. Since a part of the ends of graphene sheets having a certain size in graphene oxide is capped w...

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Abstract

The invention provides a power storage device and a method of manufacturing the same. One embodiment of the invention provides a lithium-ion secondary battery with suppressed degradation of battery characteristics due to a volume change of alloy-based negative electrode material particles in charging. A negative electrode comprises an alloy-based negative electrode material particle or an alloy-based negative electrode material whisker the surface of which is covered by a carbon film including 1 to 50 graphene layers obtained by reducing graphene oxide. For the carbon film, strong sp<2 >bonds between molecules are substantially parallel to a silicon surface so that the carbon film can be prevented from being broken even when the alloy-based negative electrode material swells and the silicon can be prevented from being broken as well. In addition, the formed carbon film has an appropriate gap and can stretch with the swelling of the alloy-based negative electrode material, and furthermore, such a gap allows lithium ions to pass through. Besides, the carbon film also can prevent the alloy-based negative electrode material from reacting with electrolyte.

Description

technical field [0001] The present invention relates to a material and an electrode used in electrical storage devices such as secondary batteries and capacitors. In particular, the present invention relates to an electrical storage device using a particulate alloy-based negative electrode material, in particular, a negative electrode material for a lithium ion secondary battery and a lithium ion secondary battery using the negative electrode material. Background technique [0002] As a negative electrode material for lithium ion secondary batteries, graphite is widely used. However, as for the theoretical discharge capacity per unit mass of graphite, since six carbon atoms are bonded to one lithium atom, the theoretical discharge capacity amounts to only 372 mAh / g. Lithium ions are intercalated between layers of graphite to be occluded by graphite. [0003] In order to break through the above-mentioned limitations, the use of silicon, germanium, aluminum, or tin, which ar...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/62H01M4/134H01M10/0525H01M10/058
CPCY02E60/122H01M4/364H01M4/386H01M4/134H01M10/0525H01M4/133H01M4/366H01M4/587H01M4/625H01M10/058Y10T29/49115Y10T29/43Y02E60/10Y02P70/50H01M4/13H01M4/38H01M4/583H01M4/139
Inventor 小国哲平长多刚竹内敏彦野元邦治荻野清文等等力弘笃桃纯平井上信洋
Owner SEMICON ENERGY LAB CO LTD
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