KR101586527B1 - Method for preparing of silicon oxide and secondary battery comprising the same - Google Patents

Abstract

The present invention relates to a process for producing silicon oxide, which comprises a process for producing silicon oxide, which comprises heat-treating silicon powder and oxygen-supplying inorganic substance, and a cathode comprising a cathode current collector and a cathode active material coated on the cathode current collector; A negative electrode including a negative electrode current collector and a negative electrode active material coated on the negative electrode current collector; And a separator interposed between the anode and the cathode, wherein the anode active material comprises silicon oxide produced by heat-treating silicon powder and an oxygen supplying inorganic material.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a silicon oxide,

The present invention relates to a method for producing silicon oxide and a secondary battery comprising the same.

The nonaqueous electrolyte secondary battery using a lithium compound as a negative electrode active material has a high voltage and a high energy density, but when charged, dendritic lithium precipitates on the lithium surface to lower the charging / discharging efficiency or cause a short circuit with the positive electrode, Due to their high reactivity, they are susceptible to heat or shock, and thus, there is a risk of explosion.

In order to solve the problem of lithium compounds, a carbon-based anode has been proposed. In the carbon-based cathode, lithium ions present in the electrolyte are not intercalated and deintercalated ) While performing the redox reaction. Although the carbonaceous anode has solved various problems of the lithium metal, it contributed greatly to popularization of the lithium battery. However, as various portable devices have become smaller, lighter, and have higher performance, high capacity of the lithium secondary battery has become an important issue.

Lithium batteries using carbon-based cathodes have inherently low battery capacity due to the porous structure of the carbon. For example, even in the case of the most crystalline graphite, the theoretical capacity is about 372 mAh / g when the composition is LiC ₆ . This is only about 10% of the theoretical capacity of lithium metal, which is 3860 mAh / g.

In order to overcome such a problem, currently active materials are metal or intermetallic compounds based anode active materials. For example, lithium batteries using metal or semimetal such as aluminum, germanium, silicon, tin, zinc, and lead as negative electrode active materials have been studied. These materials have a high capacity and a high energy density and can store and release more lithium ions than the negative electrode active material using the carbon-based material, so that a battery having a high capacity and a high energy density can be manufactured. For example, pure silicon is known to have a high theoretical capacity of 4017 mAh / g.

The present invention provides a method for mass-producing silicon oxide by a simple method by using an oxygen-supplying inorganic material as a Si-based anode active material for a lithium secondary battery.

The present invention provides a method for producing silicon oxide comprising heat treating a silicon powder and an oxygen-supplying inorganic material.

The present invention can produce silicon oxide in a simple manner by heat-treating the silicon powder and the oxygen-supplying inorganic material, and mass production of the silicon oxide can be achieved. In addition, there is an advantage that oxygen remaining and the remaining inorganic material can be reused.

The present invention provides a method for producing silicon oxide comprising heat treating a silicon powder and an oxygen-supplying inorganic material.

Hereinafter, the present invention will be described in detail.

According to the method for producing silicon oxide according to an embodiment of the present invention, silicon oxide can be manufactured by a simple method by heat-treating the silicon powder and the oxygen supplying inorganic material.

The silicon powder and the oxygen supplying inorganic material are preferably 1: 0.5 - 5 by weight.

Manufacturing method according to one embodiment of the present invention there is the heat treatment of the silicon powder and oxygen supply minerals, said oxygen supply minerals _{KIO 3, KClO 3, KCO 4} , TiClO 4, NaClO 2, Ba (ClO 4) 2 , or their Can be used. When the oxygen supplying inorganic material is heat-treated, the oxygen atoms bonded to the inorganic material are released, and the silicon powder is combined with the oxygen atoms released from the oxygen supplying inorganic material to form amorphous SiO _x (0 <x <2).

As a specific example of this, KIO ₃ can be represented by the following formula (1).

[Chemical Formula 1]

Si + KIO ₃ → 3SiO + KI

In the manufacturing method according to an embodiment of the present invention, the heat treatment is preferably performed at 600 to 1200 ° C, more specifically 800 to 1000 ° C.

The heat treatment may be performed in a vacuum atmosphere, an inert gas atmosphere, a low-pressure oxygen atmosphere, and a container in which the silicon powder and the metal oxide powder are reacted may be performed in both a closed container and an open container, The powder may be heat treated in a single or mixed state, but is not limited thereto.

The following chemical formula 2 shows that KIO ₃ is separated into KI and O ₂ by heat treatment.

(2)

KIO ₃ → KI + 3 / 2O ₂

As a result, as shown in the following chemical formula 3, the oxygen supplying inorganic material is separated into inorganic matter and oxygen by heat treatment, and the separated oxygen combines with the silicon powder to form silicon oxide.

(3)

Si + KI + 3 / 2O2 - &gt; 3SiO + KI

The method for producing silicon oxide according to the present invention is advantageous in that silicon oxide can be mass-produced by a simple method by heat-treating the silicon powder and the oxygen supplying inorganic material, and the remaining inorganic material can be reused by supplying oxygen.

In addition, when the silicon oxide is used as an anode active material of a secondary battery, an optimal SiO _x can be mass-produced in a simple manner for improving cycle performance and durability of the battery. The silicon oxide produced according to the present invention has a general formula SiO _x (0 < x < 2).

The silicon oxide itself can be used as the anode active material of the secondary battery. However, in order to further increase the electrical conductivity of the secondary battery, carbon may be added to or coated on the silicon oxide. Such carbon addition can be achieved by mechanically milling silicon oxide and carbon, and the carbon coating can be accomplished by dispersing the carbon precursor in a solvent such as tetrahydrofuran (THF), alcohol, and the like, , Followed by drying and heat treatment.

The present invention also provides a positive electrode comprising a positive electrode current collector and a positive electrode active material coated on the positive electrode current collector; A negative electrode including a negative electrode current collector and a negative electrode active material coated on the negative electrode current collector; And a separator interposed between the anode and the cathode, wherein the anode active material comprises silicon oxide produced by heat-treating a silicon powder and an oxygen supplying inorganic material.

The negative electrode active material may further include lithium or carbon. When lithium is added, the negative active material may be used as a mixture of lithium silicate by reacting with silicon oxide. When carbon is added, a mixture of silicon oxide and silicon The oxide may be coated with carbon.

The silicon oxide according to the above-described production method can be effectively used as a negative electrode active material of a secondary battery, and the secondary battery according to an embodiment of the present invention can be manufactured as follows.

The positive electrode active material composition may be prepared by mixing the positive electrode active material, the conductive material, the binder and the solvent, and then the positive electrode active material composition may be coated directly on the metal current collector and dried to produce the positive electrode.

The cathode active material may be a layered compound such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Lithium manganese oxides such as Li _{1 + y} Mn _{2 - y} O ₄ (where y is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ and LiMnO ₂ ; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ and Cu ₂ V ₂ O ₇ ; Formula _{LiNi 1 - y M y O 2} ( where, the M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, y = 0.01 ~ 0.3 Im) Ni site type lithium nickel oxide which is represented by; Formula _{LiMn 2 - y M y O 2} ( where, M = Co, Ni, Fe , Cr, and Zn, or Ta, y = 0.01 ~ 0.1 Im) or Li ₂ Mn ₃ MO ₈ (where, M = Fe, Co, Ni, Cu, or Zn); LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with an alkaline earth metal ion; Disulfide compounds; Fe ₂ (MoO ₄ ) ₃ , and the like. However, the present invention is not limited to these.

The conductive material is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, and examples thereof include graphite such as natural graphite and artificial graphite; Carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fiber and metal fiber; Metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskey such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used. Concrete examples of commercially available conductive materials include acetylene black series such as Chevron Chemical Company, Denka Singapore Private Limited and Gulf Oil Company), Ketjenblack, EC series (Available from Armak Company), Vulcan XC-72 (from Cabot Company) and Super P (from Timcal).

The binder is a component that assists in mutual bonding of the negative electrode active material and the conductive material and bonding to the current collector, and is usually added in an amount of 1 to 50 wt% based on the total weight of the mixture including the negative electrode active material. Examples of such binders include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), cellulose, polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, Polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butylene rubber, fluororubber, various copolymers, high molecular weight polymers such as polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, Vinyl alcohol, and the like.

As the solvent, N-methylpyrrolidone, acetone, water and the like can be used.

The anode active material composition may be prepared by mixing the anode active material, the conductive material, the binder and the solvent according to the present invention as described above, and the anode active material composition may be directly coated on the metal current collector or cast on a separate support, The negative electrode can be produced by laminating the peeled negative electrode active material film on the metal current collector.

A separator is disposed between the anode and the cathode to form a battery structure. The battery structure is wound or folded into a cylindrical battery case or a prismatic battery case, and then an electrolyte is injected to complete the secondary battery. Alternatively, the battery structure is laminated in a bicell structure, then impregnated with the electrolytic solution, and the resulting product is sealed in a pouch to complete the secondary battery. The separation membrane is an insulating film having high ion permeability and mechanical strength, and is formed of, for example, a sheet or nonwoven fabric made of an olefin-based polymer such as polypropylene, glass fiber, or polyethylene, which is resistant to chemicals and hydrophobicity.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. It should be noted, however, that the scope of the invention is not limited by these embodiments, but is merely given as an example.

&Lt; Example 1 >

The silicon powder and KIO ₃ were placed in a sealed container and then heat treated in a vacuum atmosphere at 600 ° C. for 30 minutes. At this time, the silicon powder and KIO ₃ were supplied at a weight ratio of 1: 0.5. After the annealing process, the closed vessel was cooled to room temperature to produce amorphous SiO 2.

&Lt; Example 2 >

The silicon powder was placed in an open container and KClO ₃ was supplied in an Ar atmosphere and heat-treated at 1200 ° C for 10 minutes. At this time, the silicon powder and KIO ₃ were in a weight ratio of 1: 5. After the annealing process, the open vessel was cooled to room temperature to produce amorphous silicon oxide.

Claims (7)

Heat treating the silicon powder and the oxygen-supplying inorganic material
Wherein the oxygen supplying inorganic material is at least one selected from the group consisting of KIO ₃ and KClO ₃ ,
Wherein the heat treatment is performed in an inert atmosphere at 600 - 1200 占 폚 for 10 minutes to 30 minutes.
The method according to claim 1,
Wherein the silicon powder and the oxygen supplying inorganic material are in a mass ratio of 1: 0.5-5.
delete delete The method according to claim 1,
The silicon oxide may be SiO _x (0 < x < 2).
A positive electrode including a positive electrode current collector and a positive electrode active material coated on the positive electrode current collector;
A negative electrode including a negative electrode current collector and a negative electrode active material coated on the negative electrode current collector; And
And a separator interposed between the anode and the cathode,
The negative electrode active material according to any one of claims 1, 2, and 5, wherein the negative electrode active material comprises silicon oxide.
The method of claim 6,
Wherein the negative electrode active material further comprises lithium or carbon.