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Negative active material for lithium secondary battery and lithium secondary battery comprising same

A negative electrode active material, lithium secondary battery technology, applied in secondary batteries, lithium storage batteries, battery electrodes, etc., can solve the problems of display capacity decline, volume expansion change, short cycle life, etc., and achieve small volume expansion and large capacity. , the effect of high capacity retention

Active Publication Date: 2012-06-20
LG ENERGY SOLUTION LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] However, when Si and Sn are used as negative electrode active materials, they have a tendency to cause a great change in volume expansion
This extreme volume expansion can lead to cracking or shattering
Therefore, metal-based anode active materials show a sudden drop in capacity and shorter cycle life when repeated charge-discharge cycles

Method used

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  • Negative active material for lithium secondary battery and lithium secondary battery comprising same
  • Negative active material for lithium secondary battery and lithium secondary battery comprising same
  • Negative active material for lithium secondary battery and lithium secondary battery comprising same

Examples

Experimental program
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Embodiment approach

[0038] An example of a method of manufacturing the negative electrode active material of the present invention is described below. However, the following method is only for illustrating one embodiment of the present invention, and the present invention is not limited thereto.

[0039] First, silicon and at least one metal element other than silicon are melted in an inert environment (S1).

[0040]In the method according to the present invention, any alloying element may be used for the silicon alloy as long as it can be used to manufacture an anode active material. For example, at least two elements selected from the group consisting of Sn, Zr, Mn, Ni, Fe, Ca, Ce, La, Cr, Al, Co, Sb, Bi, As, Ge, Pb, Zn, Cd can be used together , In, Ti and Ga, but not limited thereto.

[0041] When the raw material is melted, it is preferably melted under an inert environment to prevent inclusion of impurities therein.

[0042] Then, the molten liquid is powdered by a rapid solidification m...

Embodiment 1

[0060] (Manufacture of negative electrode active materials)

[0061] Metals were mixed by weights shown in Table 2 below, and melted by high-frequency heating under an argon atmosphere to produce alloy melts. By using a pressure of 80kg / cm 2 The alloy melt was quenched by gas spraying of argon gas, thereby producing alloy powder with an average diameter of about 100 μm. At this point, the quenching rate is 1×10 5 K / sec.

[0062] The obtained alloy powder was ball milled at 1000 rpm for 15 hours to produce silicon alloy powder.

[0063] (manufacturing of secondary batteries)

[0064] The obtained negative electrode active material powder was mixed with acetylene black as a conductive material and polyvinylidene fluoride (PVdF) as a binder at a weight ratio of 93:2:5, and then mixed with N-methyl-2 - Pyrrolidone (NMP) mixing to make negative electrode slurry. The obtained electrode slurry was coated on one surface of a copper current collector, dried at about 130°C for 2 hou...

experiment example 1

[0067] (Experimental example 1: measure the volume ratio of inactive phase)

[0068] It is not easy to measure the volume ratio of the inactive phase by a direct method, so it is measured and calculated according to the following procedure.

[0069] (1) Measure the density of silicon alloy

[0070] A hydrometer (AccuPyc 1340, Micromeritics Instrument Corp. USZ) was used as a device for measuring the density of the solid.

[0071] (2) Weight ratio of active phase (silicon phase) (B)

[0072] Equation 1

[0073]

[0074] (3) Weight ratio of inactive phase (C)

[0075] Equation 2

[0076] C=100-B

[0077] (4) Assume that the density of the active phase (silicon phase) is 2.33.

[0078] (5) Calculate the density (D) of the inactive phase

[0079] Equation 3

[0080]

[0081] (6) Volume of active phase and inactive phase (E, F)

[0082] Here, the term "volume" refers to the volume of the active phase and the inactive phase assuming that the weight of the sili...

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Abstract

The present invention relates to a negative active material for a lithium secondary battery and the lithium secondary battery comprising the same. The negative active material for the lithium secondary battery of the present invention comprises: silicon; and a silicon alloy which includes at least one kind of metal except the silicon, and is capable of being alloyed with lithium, wherein the volume of an inactive region that does not react to lithium contained within the silicon alloy is 50% to 75% relative to the entire volume of the active material. The negative active material of the present invention has a higher capacity than a carbon-based negative active material, embodies a small volume expansion after being charged and discharged, and shows a high capacity maintenance rate, thereby expressing an excellent cycle property.

Description

technical field [0001] The present invention relates to a negative electrode active material for a lithium secondary battery and a lithium secondary battery comprising the same. More particularly, the present invention relates to a negative electrode active material for a lithium secondary battery having a large capacity, excellent cycle characteristics, and low volume expansion, and a lithium secondary battery including the same. Background technique [0002] Recently, lithium secondary batteries have attracted attention as batteries having high energy density and long cycle life. Generally, a lithium secondary battery includes a negative electrode made of a carbon material or a lithium metal alloy, a positive electrode made of a lithium metal oxide, and an electrolyte made by dissolving a lithium salt in an organic solvent. [0003] Initially, lithium metal was used as an anode active material for an anode of a lithium secondary battery. However, since lithium has proble...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/38H01M10/0525H01M4/583C22C1/02
CPCY02E60/12H01M4/587H01M4/133H01M4/625C22C1/10H01M2004/027H01M4/364H01M10/052H01M4/134H01M4/38H01M4/386Y02E60/10
Inventor 郑东燮池惠珉金帝映金奇泰李龙珠
Owner LG ENERGY SOLUTION LTD
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