KR20180077794A - An cathode for an electrochemical device and an electrochemical device comprising the same - Google Patents

Abstract

The present invention relates to an anode for an electrochemical device and an electrochemical device including the same. The anode includes a current collector and an anode active material layer formed on at least one surface of the current collector. The anode active material layer includes sulfurized polyacrylonitrile (SPAN) and a porous metal oxide additive. According to the present invention, a high capacity loading anode can be manufactured, and a problem of capacity reduction due to electrode deterioration is solved to enhance the life characteristics.

Description

[0001] The present invention relates to an anode for an electrochemical device and an electrochemical device including the same.

The present invention relates to an anode for an electrochemical device and an electrochemical device including the same, wherein the anode contains sulfur-modified polyacrylonitrile.

The lithium ion battery has a theoretical energy density which is about 7 times higher than that of the current lithium ion battery, and the sulfur used as the anode material is low in cost because it is rich in resources. Due to the high interest.

However, the compound of sulfur and lithium is soluble in a non-aqueous solvent such as ethylene carbonate or dimethyl carbonate which is used as a nonaqueous electrolyte for a lithium ion secondary battery. Therefore, when a compound of sulfur and lithium is used as a cathode material, a compound of sulfur and lithium is eluted into an electrolytic solution, whereby the anode is gradually deteriorated, and battery capacity is deteriorated. As an attempt to inhibit the elution of sulfur into nonaqueous solvents, a uranium-based polymer material has been proposed which is linked by -CS-CS- bonds or -SS-bonds. In addition, in the case of SPAN which is a complex of polyacrylonitrile and sulfur, the content of sulfur is usually 50% or less. Therefore, in order to realize a battery having an energy density practically usable by applying this material, it has a sulfur content of 70% or more However, the technology required to fabricate S-PAN electrodes is limited to ² mAh / cm ² (practical capacity of sulfur: 1200 mAh / g).

An object of the present invention is to provide a high loading SPAN anode in which the degree of deterioration of the electrode is reduced even when the loading amount of the SPAN active material is increased, and an electrochemical device including such a high loading SPAN anode. It is to be easily understood that other objects and advantages of the present invention can be realized by the means shown in the claims and their combinations.

The present invention relates to a positive electrode for a lithium ion secondary battery. A first aspect of the present invention is directed to the anode, wherein the anode comprises a cathode active material layer comprising sulfurized polyacrylonitrile (SPAN), a conductive material and a porous metal oxide additive.

According to a second aspect of the present invention, in the first aspect of the present invention, the sulfur-modified polyacrylonitrile is obtained by heating sulfur and polyacrylonitrile in a closed non-oxidizing atmosphere, And n is an integer of 1 to 4 in the following formulas (2) to (5): "

 [Chemical Formula 1]

(2)

(3)

[Chemical Formula 4]

[Chemical Formula 5]

In a third aspect of the present invention, in the first or second aspect, the sulfur-modified polyacrylonitrile has a main peak in the vicinity of 1330 cm ^-1 of the Raman shift in the Raman spectrum and has a main peak in the range of 200 cm ^-1 to 2000 cm ^-1 in the range of ^{1561cm -1, 1512cm -1, 1447cm -1} , 1150cm -1, 996m -1, 942cm -1, 802cm -1, 474cm -1, the peak at 391cm ^-1, 365cm ^-1, 305cm ^-1 near the It exists.

In a fourth aspect of the present invention, in any one of the first to third aspects, the porous metal oxide additive is derived from metal-organic frameworks (MOFs).

In a fifth aspect of the present invention, in the fourth aspect, the MOFs are Prussian blue analogues (PBAs).

In a sixth aspect of the present invention, in the fourth aspect, the metal oxide additive is at least one of the compounds represented by the following general formula (6).

[Chemical Formula 6]

M _{1. 8} Co _{1. 2} O4

In the above formula, M is at least one selected from the group consisting of Zn, Co, Cu, Fe, Ni and Mn.

In a seventh aspect of the present invention, in any one of the first to sixth aspects, the content of the additive is 1 to 10% by weight based on 100% by weight of the cathode active material layer.

According to an eighth aspect of the present invention, in any one of the first to seventh aspects, the conductive material includes a linear conductive material.

In a ninth aspect of the present invention, in any one of the first to eighth aspects, the linear conductive material is at least one of carbon fiber and vapor grown carbon fiber (VGCF).

In a tenth aspect of the present invention, in any one of the first to ninth aspects, the cathode active material layer further comprises a binder resin, and the binder resin includes at least one of a polyimide resin and a polyamide- .

According to an eleventh aspect of the present invention, in any one of the first to tenth aspects, the anode includes the current collector and the cathode active material layer disposed on at least one surface of the current collector, The loading amount of SPAN, a cathode active material, is more than ² mAh / cm ² based on one side of the whole.

A twelfth aspect of the present invention is directed to a lithium ion secondary battery, wherein the lithium ion secondary battery includes a positive electrode having the above-described characteristics.

The anode according to the present invention can maintain the shape of the electrode stably without generating cracks on the surface and / or inside of the electrode even when the loading amount is increased as compared with the conventional SPAN anode. Therefore, it is possible to manufacture a high capacity loading anode of SPAN, and it is possible to solve the problem of reduction in capacity due to electrode deterioration, thereby improving lifetime characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description of the invention given below, serve to further the understanding of the technical idea of the invention, And should not be construed as limiting. On the other hand, the shape, size, scale or ratio of the elements in the drawings incorporated herein can be exaggerated to emphasize a clearer description.
1 shows a cross section of an anode according to the present invention.
2 shows an SEM image of the PBAs prepared in Production Example 2-1.
3A and 3B show an SEM image of the metal oxide additive produced in Production Example 2-1 of the present invention.
4 shows an SEM image of the PBAs prepared in Production Example 2-2.
5A and 5B show an SEM image of the metal oxide additive produced in Production Example 2-2 of the present invention.
6 shows an SEM image of the PBAs prepared in Preparation Example 2-3.
7A and 7B show SEM images of the metal oxide additives prepared in Production Example 2-3 of the present invention.
8 shows an SEM image of the PBAs prepared in Production Example 2-4.
9A and 9B show an SEM image of the metal oxide additive made in Production Example 2-4 of the present invention.
10 shows results of life characteristic tests of the batteries made in Experimental Examples 1 to 4 and Comparative Examples.

The terms used in the specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may properly define the concept of a term to describe its invention in its best possible way And should be construed in accordance with the principles and meanings and concepts consistent with the technical idea of the present invention. Therefore, the constitution shown in the embodiments described herein is the most preferable embodiment of the present invention and does not represent all the technical ideas of the present invention, so that various equivalents It should be understood that water and variations may be present.

The present invention relates to an anode for an electrochemical device and an electrochemical device including the anode.

In the present invention, the electrochemical device includes all devices that perform an electrochemical reaction. Examples of the electrochemical device include a capacitor, such as a primary cell, a secondary cell, a fuel cell, a solar cell, or a supercapacitor, . In particular, the secondary battery is a lithium secondary battery including a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery. In the present invention, the lithium secondary battery is a lithium-sulfur battery including sulfur as a cathode active material.

The positive electrode includes a current collector and a positive electrode active material layer formed on at least one surface of the current collector. The cathode active material layer includes sulfurized polyacrylonitrile (SPAN) as a cathode active material, and further includes a porous metal oxide additive.

In the present invention, the positive electrode active material layer has a loading amount of SPAN, which is a positive electrode active material, of ² mAh / cm ² or more based on one side of the current collector.

In the present invention, the sulfurized polyacrylonitrile (SPAN) may include at least one of those represented by the following formulas (1) to (5). However, in addition to those represented by the general formulas (1) to (5), various types of sulfur-modified polyacrylonitrile may be included. In the following formulas (2) to (5), n is an integer of 1 to 4. In one specific embodiment of the present invention, the sulfur-modified polyacrylonitrile is represented by the following general formula (3), (4) or (4)

 [Chemical Formula 1]

(2)

(3)

[Chemical Formula 4]

[Chemical Formula 5]

The SPAN may be obtained by, for example, heating sulfur and polyacrylonitrile in a closed non-oxidizing atmosphere.

The particle size of the sulfur powder is in the range of 40 탆 to 150 탆, or 40 탆 to 100 탆. When the particle diameter is within the above range, the reactivity of the raw material powder is increased, the SPAN synthesis reaction time can be shortened, and a uniform SPAN can be obtained. On the other hand, when the particle diameter is too small beyond the above range, the processability is degraded.

The polyacrylonitrile has a weight average molecular weight of from 10,000 to 3,000,000 or from 1,000,000 to 2,000,000 as a powder. The particle diameter of the polyacrylonitrile powder is in the range of 0.5 탆 to 50 탆 or 1 탆 to 10 탆 as observed by an electron microscope. When the particle diameter satisfies the above range, the reactivity of the raw material powder is increased, and a faster and more uniform sulfur-modified polyacrylonitrile can be obtained. On the other hand, if it exceeds 10 m, the reactivity of the battery may be lowered. If the particle diameter of the sulfur powder is less than 0.5 占 퐉, the processability may be lowered.

On the other hand, as the particle diameter of the polyacrylonitrile powder increases, the cycle characteristics of the battery may be deteriorated. Therefore, the diameter of the PAN particles should be in the range of 0.1 탆 to 20 탆 or 0.5 탆 to 10 탆. On the other hand, the blending ratio of the sulfur powder and the polyacrylonitrile powder is not particularly limited, but is preferably 50 to 1000 parts by mass, or 50 to 500 parts by mass, or 50 to 350 parts by mass of the sulfur powder relative to 100 parts by mass of the polyacrylonitrile powder Mass part. When the mixing ratio of the sulfur powder and the polyacrylonitrile powder is within the above range, the molten sulfur easily penetrates into the polyacrylonitrile powder and uniform sulfur-modified polyacrylonitrile can be obtained.

The raw powder is heated in a closed non-oxidizing atmosphere using the sulfur powder and polyacrylonitrile powder as raw material powders. By this process, the sulfur in the vapor state reacts with the polyacrylonitrile simultaneously with the cyclization reaction of the polyacrylonitrile, and the polyacrylonitrile denatured by the sulfur can be obtained.

The enclosed atmosphere means an atmosphere in which the sealed state is maintained to such an extent that the leakage of sulfur is prevented and the vapor of sulfur generated by heating is not lost. Also, the non-

A sulfur gas atmosphere, an inert gas atmosphere such as nitrogen or argon, or the like, in which the oxygen concentration is low enough to prevent the oxidation reaction from proceeding. A specific method for heating the raw material powder in a closed non-oxidizing atmosphere is not particularly limited, but for example, a raw material powder is put in a container which maintains hermeticity to the extent that sulfur vapor is not lost, It may be heated in a gas atmosphere. Alternatively, the mixture of the sulfur powder and the polyacrylonitrile powder may be heated while being vacuum-packed with a packaging material composed of a material which does not react with sulfur vapor such as an aluminum laminate film. In this case, it is preferable to heat the raw material powder vacuum-packed with the packaging material in a pressure-resistant container such as an autoclave sealed with water to prevent the packaging material from being damaged by the generated sulfur vapor. According to this method, since the packaging material is pressurized by the generated steam, it can be prevented that the packaging material is inflated by the sulfur vapor and is broken.

On the other hand, when heating the raw material powder composed of the sulfur powder and the polyacrylonitrile powder, only the mixture of only the two powders may be heated. However, for example, the molded body obtained by molding the mixture into pellets may be heated.

The heating temperature is 250 to 500 占 폚, or 250 to 400 占 폚. If the heating temperature is less than 250 ° C, the reaction between sulfur and polyacrylonitrile does not occur. If the heating temperature exceeds 500 ° C, sulfur is desorbed and the content of sulfur in the sulfur-modified polyacrylonitrile lowers. When the content of sulfur is lowered, the electric capacity of the battery is lowered. In addition, the sulfur-modified polyacrylonitrile is not decomposed by the heating temperature during the production.

The heating time is not particularly limited and may vary depending on the heating temperature. Generally, the mixture is in the above temperature range for 10 minutes to 10 hours, or 30 minutes to 6 hours.

According to the above-described method, the ring-closing reaction of polyacrylonitrile and the reaction of sulfur with polyacrylonitrile occur at the same time, and polyacrylonitrile denatured by sulfur can be obtained.

In one specific embodiment of the present invention, the sulfur-modified polyacrylonitrile comprises carbon, nitrogen and sulfur. It may also contain small amounts of oxygen and hydrogen. The composition of the SPAN is 40 to 60 mass% of carbon, 15 to 30 mass% of sulfur, 10 to 25 mass% of nitrogen, and 1 to 5 mass% of hydrogen.

In the sulfur-modified polyacrylonitrile, as a result of X-ray diffraction according to the CuK? Ray, it is preferable that the peak of the sulfur disappears and only the peak of the broad is observed near the diffraction angle (2?) Of 20 to 30 占 폚. That is, in sulfur-modified polyacrylonitrile, it is preferable that sulfur does not exist as a single substance but exists in a state in which it is bonded to polyacrylonitrile with progress of ring-closing.

In the Raman spectrum of the nitrile to the sulfur-modified polyacrylonitrile is a main peak present in the vicinity of 1,330cm ^-1 of Raman shift, and 200cm ^-1 ~ ^-1 1561cm in the range of 2000 cm ^-1, 1,512 cm ^-1, 1,447 cm ^{-1, 1,150 cm -1, 996 m -1,} 942 cm -1, it is preferred to 802cm ^-1, the peak exists in the ^{474 cm -1, 391 cm -1,} 365 cm -1, near 305 cm-1.

In the present invention, the porous metal oxide additive is derived from metal-organic frameworks (MOFs), and is specifically a porous metal oxide derived from Prussian blue analogues (PBAs).

In the present invention, PBAs are structures in which organic and inorganic subunits are strongly chemically bonded. Herein, the organic subunit is an organic ligand in which carbon and nitrogen are triple bonded. The organic subunit binds with an inorganic subunit containing a metal to form a three-dimensional structure. Due to such a structure, PBAs have a structurally porous property. In the present invention, the PBAs have a specific surface area of 500 to 1,500 m ² / g or 700 to 900 m ² / g.

In one specific embodiment of the present invention, the porous metal oxide additive is at least one of the compounds represented by the following formula (6).

[Chemical Formula 6]

M _{1. 8} Co _{1. 2} O ₄

In Formula 6, M is at least one selected from the group consisting of Zn, Co, Cu, Fe, Ni, and Mn.

In one embodiment of the present invention, the metal oxide additive is a result of high-temperature heat treatment of PBAs, and the CN bond is oxidized by the heat treatment to generate and remove CO ₂ and N _x Y _y . Accordingly, the metal oxide additive has porosity higher than that of PBAs. Also, the pores present in the metal oxide additive are interconnected pores connected to each other. Due to such porous properties, the metal oxide additive facilitates the movement of the organic electrolytic solution including lithium ions, thereby promoting the electrochemical reaction. In the present invention, the heat treatment temperature of the PBAs is 400 ° C to 600 ° C. When the heat treatment temperature satisfies the above range, the gas generation rate is increased and the porosity is improved. However, if the heat treatment temperature is excessively higher than 600 ° C., the pore size may excessively increase, which may result in a problem of lowering the energy density per electrode weight. Therefore, it is preferable that the heat treatment temperature satisfies the above-mentioned range in consideration of the smooth entry and exit of the electrolyte solution and the energy density of the electrode. In one specific embodiment of the present invention, the porosity of the metal oxide additive is 20% to 60%, or 20% to 50%. The size of the pores in the metal oxide is 4 nm to 40 nm or 10 nm to 40 nm or 20 nm to 40 nm based on the largest pore size. In the present invention, the measurement of the porosity distribution is not limited to a specific method, and can be measured by, for example, the Barrett-Joyner-Halenda (BJH) method.

In the present invention, the content of the additive is 1 to 10% by weight based on 100% by weight of the positive electrode active material layer. When the above range is satisfied, the high capacity characteristics of the anode are improved and the problem of electrode cracking is reduced.

The positive electrode current collector is made to have a thickness of 3 to 500 mu m. Such an anode current collector does not cause chemical change in the battery, but may have conductivity. For example, surface of copper, steel, stainless steel, aluminum, nickel, titanium, sintered carbon, copper or stainless steel surface treated with carbon, nickel, titanium, silver or the like, aluminum-cadmium alloy can be used. Like the positive electrode current collector, the negative electrode current collector can form fine irregularities on the surface to increase the adhesive force of the negative electrode active material, and various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric are possible.

In one specific embodiment of the present invention, the cathode active material layer may further include a conductive material and a binder.

The conductive material is used for imparting conductivity to the electrode. In the present invention, the conductive material includes a linear conductive material. The linear conductive material is at least one of carbon fiber and vapor grown carbon fiber (VGCF). The linear conductive material has the effect of reducing the generation of cracks in the electrode when the loading amount of the SPAN cathode active material is high and preventing the change of the anode form (volume) during charging and discharging.

In addition to the above linear conductive materials, carbon conductive materials such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, and carbon fiber; Metal powders such as copper, nickel, aluminum, and silver, or metal-based materials such as metal fibers; Conductive polymers such as polyphenylene derivatives; Or a mixture of these materials.

The binder serves to adhere the anode active material particles to each other and to adhere the anode active material to the current collector. The binder specifically includes polyimide, polyamideimide, polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinylchloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide Polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, and the like However, the present invention is not limited thereto.

The present invention also provides an electrochemical device including the positive electrode, wherein the electrochemical device includes a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode.

The negative electrode uses a lithium metal thin film and / or a lithium metal powder as an anode active material. The negative electrode active material layer including the negative electrode active material in the negative electrode has a thickness of about 50 탆 to 200 탆.

The separation membrane can be used without limitation, as long as it can be used as a separation membrane material of an electrochemical device. Examples of such a separator include a polyolefin, a polyethylene terephthalate, a polybutylene terephthalate, a polyacetal, a polyamide, a polycarbonate, a polyimide, a polyether ether ketone, a polyether sulfone, a polyphenylene oxide, , A polymer resin such as polyethylene naphthalene, or a nonwoven fabric may be used. Further, in one specific embodiment of the present invention, the separation membrane may be a laminated separation membrane in which different types of substrates are sequentially stacked.

Further, the electrochemical device includes the electrolytic solution, and the electrolytic solution includes a non-aqueous solvent and a lithium salt.

In the present invention, the non-aqueous solvent may further include at least one selected from carbonate, ester, ether, ketone, alcohol, and aprotic solvents. Examples of the carbonate solvent include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC) EC), propylene carbonate (PC), and butylene carbonate (BC) may be used. As the ester solvent, methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate , gamma -butyrolactone, decanolide, valerolactone, mevalonolactone, caprolactone, and the like can be used. Examples of the ether solvent include dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, and tetrahydrofuran. As the ketone solvent, cyclohexanone may be used have. As the alcoholic solvent, ethyl alcohol, isopropyl alcohol and the like can be used. As the aprotic solvent, R-CN (R is a linear, branched or cyclic hydrocarbon group having 2 to 20 carbon atoms, , A double bond aromatic ring or an ether bond), amides such as dimethylformamide, dioxolanes such as 1,3-dioxolane, and sulfolanes.

The lithium salt is dissolved in an organic solvent to act as a source of lithium ions in the cell to enable operation of a basic lithium secondary battery and to promote the movement of lithium ions between the anode and the cathode. In the present invention, the lithium salt is contained at a concentration of 0.1 mol / liter to 2 mol / liter in the electrolytic solution. The lithium salt _{LiFSI, LiPF 6, LiBF 4,} LiSbF 6, LiAsF 6, LiN (SO 2 C 2 F 5) 2, Li (CF 3 SO 2) 2 N, LiN (SO 3 C 2 F 5) 2, _{LiC 4 F 9 SO 3, LiClO} 4, LiAlO 2, LiAlCl 4, LiN (C x F 2x + 1 SO 2) (C y F 2y + 1 SO 2) ( where, x and y are natural numbers), LiCl, LiI and LiB (C ₂ O ₄ ) ₂ (lithium bis (oxalato) borate (LiBOB)).

The present invention also provides a battery module including the secondary battery as a unit cell, a battery pack including the battery module, and a device including the battery pack as a power source.

At this time, specific examples of the device include a power tool that is powered by an electric motor and moves; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and the like; An electric motorcycle including an electric bike (E-bike) and an electric scooter (E-scooter); An electric golf cart; And a power storage system, but the present invention is not limited thereto.

Hereinafter, the present invention will be described in further detail with reference to the following examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

Manufacturing example

Production Example 1) Production of SPAN

The PAN polymer (Sigma-aldrich, Mw 160,000) and sulfur powder (Sigma-aldrich, 99.98% trace metals basis) were mixed at a weight ratio of 1: 4 and then heat treated. The heat treatment was performed in an Ar atmosphere, and the temperature was increased from room temperature (25 ° C) to 450 ° C at a rate of 10 ° C / minute.

Production Example 2) Preparation of Porous Metal Oxide Additive

First, PBAs were synthesized by using various metal salts and CN ligands, and then heat treated in air atmosphere to synthesize porous metal oxide additives. The heat treatment was performed at a rate of 10 ° C / minute from room temperature (25 ° C) to 400 ° C, and then maintained at 400 ° C for 2 hours. The transition metal salts, the free ligands and the prepared porous metal oxide additives used in each production example are shown in Table 1 below. 2, 4, 6 and 8 show SEM photographs of the PBAs prepared in Production Examples 2-1, 2-2, 2-3 and 2-4, respectively. 3A and 3B, Figs. 5A and 5B, Figs. 7A and 7B, and Figs. 9A and 9B are graphs showing the effect of the porous metal oxide additives prepared in Production Examples 2-1, 2-2, 2-3 and 2-4 SEM photographs.

Manufacturing example The transition metal salts and organic ligands used PBAs manufactured
(n is an integer of less than 5) The finally synthesized porous metal oxide additive 2-1 Mn (CH ₃ COOH) ₂ .4H ₂ O
K ₃ [Co (CN) ₆ ] ₂ Mn ₃ [Co (CN) ₆ ] ₂ .nH ₂ O Mn _{1 . 8} Co _{1 . 2} O ₄ 2-2 Co (NO ₃ ) ₂ .6H ₂ O
K ₃ [Co (CN) ₆ ] ₂
Co ₃ [Co (CN) ₆ ] ₂ .nH ₂ O Co _{1 . 8} Co _{1 . 2} O ₄ 2-3 Ni (NO ₃ ) ₂ .6H ₂ O
K ₃ [Co (CN) ₆ ] ₂ Ni ₃ [Co (CN) ₆ ] ₂ .nH ₂ O Ni _{1 . 8} Co _{1 . 2} O ₄ 2-4 Cu (NO ₃ ) ₂ .3H ₂ O
K ₃ [Co (CN) ₆ ] ₂ Cu ₃ [Co (CN) ₆ ] ₂ .nH ₂ O Cu _{1 . 8} Co _{1 . 2} O ₄

6 mmol of K ₃ [Co (CN) ₆ ] ₂ was dissolved in 2 ml of water to prepare a first aqueous solution. Next, 12 mmol of the transition metal salt was dissolved in 20 ml of water to prepare a second aqueous solution. The aqueous solutions 1 and 2 were mixed at room temperature and the resulting precipitate was filtered. The precipitate was washed with water and dried to obtain PBAs.

Next, the PBAs were heat-treated at atmospheric conditions to finally obtain a metal oxide additive having a porous property. The heat treatment was carried out at about 500 캜 for about 2 hours.

Examples 1 to 4 Preparation of positive electrode and battery

The SPAN prepared in Preparation Example 1, the metal oxide additive, the conductive material (carbon black), and the binder (SBR / CMC, 70:30 weight ratio) prepared in 2 above were mixed at a weight ratio of 75: 5: DI water and mixed to prepare a positive electrode mixture. The prepared positive electrode mixture was coated on a 20 탆 thick aluminum foil as a positive electrode current collector to a thickness of 60 탆 and dried to prepare a positive electrode.

As the cathode, a lithium metal thin film (160 탆 in thickness) was used. The electrode assembly was housed in a battery case with a separator (polyethylene separator, thickness: 20 mu m) interposed between the negative electrode and the positive electrode, and the concentration of 1P LiPF ₆ and VC (vinyl carbonate, additive) (Ethylene carbonate: Methyl ethyl carbonate = 2: 1 by volume) contained in an amount of 3 wt% was used as an electrolytic solution to prepare a full cell.

The metal oxide additives used in Examples 1 to 4 are shown in Table 2 below.

Example The metal oxide additive used One Mn _{1 . 8} Co _{1 . 2} O ₄ 2 Co _{1 . 8} Co _{1 . 2} O ₄ 3 Ni _{1 . 8} Co _{1 . 2} O ₄ 4 Cu _{1 . 8} Co _{1 . 2} O ₄

Comparative Example 1 Preparation of anode and battery

The SPAN, the conductive material (carbon black), and the binder (SBR / CMC, 70:30 weight ratio) prepared in Preparation Example 1 were charged into DI water at a weight ratio of 80:10:10 respectively and mixed to prepare a positive electrode mixture, The prepared positive electrode mixture was coated on an aluminum foil having a thickness of 20 탆 as a positive current collector to a thickness of 60 탆 and then dried to prepare a positive electrode.

As the cathode, a lithium metal thin film (160 탆 in thickness) was used. The electrode assembly was housed in a battery case with a separator (polyethylene separator, thickness: 20 mu m) interposed between the negative electrode and the positive electrode, and the concentration of 1P LiPF ₆ and VC (vinyl carbonate, additive) (Ethylene carbonate: Methyl ethyl carbonate = 2: 1 by volume) contained in an amount of 3 wt% was used as an electrolytic solution to prepare a full cell.

Evaluation of battery characteristics

The batteries of Examples 1 to 4 and Comparative Example 1 were charged and discharged at a constant current of 1.0 C at a constant current of 3.0 V and discharged at a constant current of 1.0 C to 1.0 V repeatedly to evaluate the capacity retention rate. This is shown in Fig. As a result, it was confirmed that the batteries of Examples 2 to 4 had higher capacity retention ratios as compared with the batteries prepared in the comparative examples, and as a result, they had excellent room temperature life characteristics.

[Description of Symbols]

100 ... electrode layer

101 ... electrode active material (SPAN particle)

102 ... conductive material

103 ... Porous metal oxide additive

104 ... groundwork

Claims (12)

A positive electrode for a lithium ion secondary battery comprising a positive electrode active material layer comprising sulfurized polyacrylonitrile (SPAN), a conductive material and a porous metal oxide additive.
The method according to claim 1,
The sulfur-modified polyacrylonitrile is obtained by heating sulfur and polyacrylonitrile in a closed non-oxidizing atmosphere, and includes at least one of those represented by the following formulas (1) to (5) and n is an integer of 1 to 4, and a positive electrode for a lithium ion secondary battery:
[Chemical Formula 1]

(2)

(3)

[Chemical Formula 4]

[Chemical Formula 5]

The method according to claim 1,
The sulfur-denatured polyacrylonitrile had main peaks in the Raman spectrum near 1330 cm-1 of Raman shift and had peak peaks at 1561 cm-1, 1512 cm-1 and 1447 cm-1 in the range of 200 cm-1 to 2000 cm- 1, 1150 cm -1, 996 m -1, 942 cm -1, 802 cm -1, 474 cm -1, 391 cm -1, 365 cm -1 and 305 cm -1. Anode for Lithium Ion Secondary Battery.
The method according to claim 1,
Wherein the porous metal oxide additive is derived from metal-organic frameworks (MOFs).
5. The method of claim 4,
Wherein the MOFs are Prussian blue analogues (PBAs).
6. The method of claim 5,
Wherein the PBAs are at least one of compounds represented by the following general formula (6): < EMI ID =

[Chemical Formula 6]
M _{1. 8} Co _{1. 2} O4
In the above formula, M is at least one selected from the group consisting of Zn, Co, Cu, Fe, Ni and Mn.
The method according to claim 1,
Wherein the content of the additive is 1 to 10% by weight based on 100% by weight of the positive electrode active material layer.
The method according to claim 1,
Wherein the conductive material comprises a linear conductive material.
The method according to claim 1,
Wherein the linear conductive material is at least one of carbon fiber and vapor grown carbon fiber (VGCF).
The method according to claim 1,
Wherein the positive electrode active material layer further comprises a binder resin, and the binder resin includes at least one of a polyimide resin and a polyamide-imide resin.
The method according to claim 1,
The positive electrode includes the current collector and the positive electrode active material layer disposed on at least one surface of the current collector. The positive electrode active material layer has a loading amount of SPAN, which is a positive electrode active material, of ² mAh / cm ² or more Anode for a lithium ion secondary battery.
12. A lithium ion secondary battery comprising a positive electrode according to any one of claims 1 to 11.

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