KR20180137776A - High capacity negative electrode and lithium ion battery - Google Patents

Abstract

Provided are a high capacity cathode and a high voltage lithium ion battery using the same. According to the present invention, a complex of a copper organic precursor is prepared with a composition comprising i) an aliphatic organic amine solvent, ii) an organic copper salt, iii) an alkanolamine having a hydroxyl group and an amino functional group in an alkane main chain, and iv) graphite. Then, as the cathode of the lithium ion battery, the same is mixed with graphite and heated and decomposed, so that gases generated during decomposition widen an interval of graphite.

Description

HIGH CAPACITY NEGATIVE ELECTRODE AND LITHIUM ION BATTERY BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention relates to a high capacity cathode and a high voltage lithium ion battery using the same.

2. Description of the Related Art [0002] A secondary battery using an alkali metal such as lithium has been attracting attention due to miniaturization of electronic devices and the like. When alkali metals such as lithium are used as a single substance in a cathode, dendrites (dendritic crystals) are generated and grown on the dissolution-precipitation surface of the metal by repeating charge and discharge, that is, dissolution-precipitation process of alkali metal, Thereby causing a short circuit in the battery. It has been found that the use of an alkali metal alloy instead of an alkali metal in a negative electrode for a secondary battery suppresses the generation of dendrites compared to the alkali metal alone and improves the charge-discharge cycle characteristics. However, even if an alkali metal alloy is used, a short circuit inside the battery due to the formation of dendrite may occur.

Recently, organic materials such as carbon or conductive polymer have been developed by using alkali metal ion absorption-release process instead of dissolution-precipitation process or dissolution-precipitation-solid diffusion process of metal such as alkali metal or its alloy . When carbon is used as an anode active material, the amount of lithium inserted between carbon layers is the upper limit of one lithium atom, that is, C ₆ Li, with respect to 6 carbon atoms, and the capacity per unit weight of carbon is 372 mAh / g. Carbon has a wide structure ranging from amorphous carbon to graphite, and the size of the rough surface of carbon varies depending on the starting material, manufacturing method and the like.

The carbon materials which have been conventionally used as negative electrode active materials are disclosed in, for example, JP-A-3-289068, etc. However, these carbon materials do not reach the above-mentioned theoretical capacity, Li / Li + potential linearly increased at the time of deintercalation to show a sufficient capacity in a usable potential range when an actual cell system was constituted, and a negative electrode satisfactory as a negative electrode capacity at the time of preparing the battery could not be produced.

A method has been developed in which graphite powder, copper sulfate and other copper salts are mixed, water is added to dissolve copper sulfate, an alkaline compound is added at a molar ratio of 2 times or more of the amount of copper ions present, left to stand, and then filtered. However, according to this method, not only the process is complicated, but also it is impossible to provide a sufficiently high-capacity cathode even when the composite thus prepared is applied.

The present invention relates to a graphite powder having a large capacity and a wide gap which can simplify the electrode manufacturing process by providing an electrode in which copper oxide is present in contact with graphite capable of intercalating lithium and which is obtained by mixing a conductive material and a binder, Method.

The present invention also provides a high-capacity lithium-ion battery having a high capacitance by using a high-capacity composite graphite negative electrode or an electrode preventing capacity by using the above-mentioned graphite powder having a wide gap.

According to one aspect of the present invention, there is provided a composition for synthesizing a graphite powder having a wide gap, comprising: i) an aliphatic organic amine solvent, ii) an organic copper salt, iii) an alkanolamine having a hydroxyl group and an amino functional group in the alkane main chain, iv) a graphite.

According to another aspect of the present invention, there is provided a method for producing graphite powder, which comprises the steps of decomposing a composition containing copper ions on all or a part of a surface of graphite particles by heat- . ≪ / RTI >

According to another aspect of the present invention, there is provided a process for producing copper oxide on a surface by decomposing a compound containing copper ion on all or a part of the surface of graphite particles capable of intercalating lithium ions, A negative electrode comprising a bonded graphite composite, a conductive material and a binder, wherein the graphite composite with copper oxide provides a high capacity negative electrode which is the above-described expanded carbon powder.

According to another aspect of the present invention, there is provided a lithium ion battery including the above-described high capacity cathode.

According to the present invention, the graphite powder having a high degree of contact due to the composite treatment of copper oxide and graphite can easily form copper oxide and at the same time can produce a graphite powder with a high yield.

Further, the negative electrode using the graphite powder having a wider spacing according to the present invention is an electrode in which copper oxide is in contact with all or a part of the surface of graphite particles capable of intercalating lithium, and a conductive material and a binder, . This is believed to be due to the fact that the copper oxide produces a complex oxide of lithium and copper that reversibly changes to that electrochemically reduced.

In addition, the lithium ion battery using the negative electrode according to the present invention can provide a lithium ion battery excellent in high voltage while simplifying the electrode manufacturing process.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow chart of a process for producing graphite powder with a wide gap according to the present invention.
FIG. 2 is a graph showing the physical properties of graphite powder (corresponding to Example 4) and untreated graphite powder obtained according to an embodiment of the present invention in accordance with an X-ray diffractometer (Bruker / New DB Advance) It is a graph.
FIG. 3 is a graph comparing the physical properties of graphite powder and untreated graphite powder obtained according to an embodiment of the present invention, according to Raman spectroscopy (Renishaw) and comparing the results.
FIG. 4 is a graph for confirming the result of the capacity change depending on the addition of the copper ion complex. FIG.
FIG. 5 is a graph showing a charge / discharge test result of a lithium ion battery coin cell using graphite powder (a) and untreated graphite powder (b) each having a wide gap obtained according to an embodiment of the present invention as active materials.

Hereinafter, a graphite powder with a wide gap according to specific embodiments of the present invention, a method for manufacturing the same, a high capacity cathode and a lithium ion battery using the same will be described in detail. For reference, the present invention is not limited to the specific embodiments.

The present invention provides a composition for synthesizing a graphite powder having a wide contact area and enhanced electrode reactivity of copper oxide due to reduction in resistance component due to contact between particles due to the composite treatment of copper oxide and graphite, comprising: i) A solvent, ii) an organic copper salt, iii) an alkanolamine having a hydroxyl group and an amino functional group in the alkane main chain, and iv) graphite.

In one embodiment of the invention, the components i), ii) and iii) are present in the form of a copper complex, which has copper as the central metal derived from component ii) and contains components i) and i) And a ligand derived from component iii).

The component i) means a chemical substance capable of dissolving at least a part of the ii) the organic copper salt and the iii) the alkanolamine having the hydroxyl group and the amino functional group in the alkane main chain. Such materials include, for example, primary amines including propylamine, n-butylamine, hexylamine, octylamine; Secondary amines including diisopropylamine, di (n-butyl) amine; Tertiary amines including trioctylamine, tri-n-butylamine; Or an aliphatic organic amine of an alkylamine, including ethylamine, propylamine, butylamine, trioctylamine. If an aromatic organic amine is used here, the decomposition temperature of the copper ion complex may be increased, which is not preferable.

If necessary, a nonaqueous solvent may be added in addition to the aliphatic organic amine. Specific examples thereof include PEGMEA, ethyl acetate, n-butyl acetate,? -Butyrolactone, 2,2,4-trimethylpentanediol-1,3 Ester solvents such as monoisobutyrate, butyl carbitol acetate, butyl oxalate, dibutyl phthalate, dibutyl benzoate, butyl cellosolve acetate, ethylene glycol diacetate and ethylene glycol diacetate; Ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; Aliphatic or aromatic hydrocarbon solvents such as toluene, xylene, Aromasol, chlorobenzene, hexane, cyclohexane, decane, dodecane, tetradecane, hexadecane, octadecane, octadecene, nitrobenzene and o-nitrotoluene; Ether solvents such as diethyl ether, dipropyl ether, dibutyl ether, dioxane, tetrahydrofuran, octyl ether and tri (ethylene glycol) dimethyl ether; Butanol, isobutanol, hexanol, isopropyl alcohol, ethoxy ethanol, ethyl lactate, octanol isopropyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monomethyl ether, Alcohol solvents such as benzyl alcohol, 4-hydroxy-3-methoxybenzaldehyde, isodecanol, butyl carbitol, terpineol, alpha-terpineol, beta-terpineol and cineol; But are not limited to, glycerol, glycol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, butanediol, hexylene glycol, , Polypropylene glycol, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (ethyl cellosolve), ethylene glycol monobutyl ether (butyl cellosolve), diethylene glycol monoethyl ether, diethylene glycol monobutyl A polyol solvent such as ether; Amide solvents such as N-methyl-2-pyrrolidone (NMP), 2-pyrrolidone, N-methylformamide, N, N-dimethylformamide and N, N-dimethylacetamide; Diethersulfone, tetramethylenesulfone, dimethylsulfoxide, diethylsulfoxide, and the like, or a sulfoxide solvent.

The content of component i) may be in the range of 10 to 30% by weight, preferably 15 to 30% by weight, more preferably 15 to 26% by weight, based on the total weight of the composition. If the content of the component i) is less than 10% by weight, the copper precursor does not completely react as a ligand, thereby causing problems in dispersion and reduction. When the content exceeds 30% by weight, Which is undesirable.

The component ii) can be, for example, acetate, citrate And at least one organic copper salt selected from formate, but are not limited thereto.

The organic copper salt of component ii) is produced by decomposing graphite powder having a wide gap and producing CO ₂ , CO and H ₂ O, which are decomposed by heat and can be easily removed, as decomposition products, Which in turn influences the graphite of component iv) to provide an effect of widening the layer of graphite and also forms only gaseous by-products which protect the copper formed in situ from oxidation. These by-products are easy to remove and residual impurities do not remain in the formed copper film.

Specifically, for example, copper formate is characterized in that CO ₂ , CO, and H ₂ O, which are volatile materials, are generated as decomposition products while being reduced to metal according to the mechanism shown in the following Reaction Schemes 1 and 2. For reference, the organometallic salts such as copper formate are known to be inadequate because they mostly dissolve only in water and do not dissolve in most other solvents.

[Reaction Scheme 1]

Cu (HCOO) ₂ ? Cu + CO + CO ₂ + H ₂ O

[Reaction Scheme 2]

Cu (HCOO) ₂ ? Cu + 2CO ₂ + H ₂

On the other hand, in the case of the organic copper salt, depending on the reaction mechanism, hydrogen gas or aldehyde having a reducing power can be generated. Therefore, even if no additional reducing agent is added during the heat treatment in the oxidation atmosphere described later, Can be achieved with high yield. In addition, the decomposition temperature of the copper organic precursor itself can be lowered.

The content of the component ii) may be 30 to 50 wt%, 30 to 48 wt%, 32 to 50 wt%, or 32 to 48 wt% based on the total weight of the composition. If the content of the component ii) is less than 30 wt%, there is a problem in forming the precursor because the equivalence ratio with the other components (i, iii) does not match. If the content exceeds 50 wt%, impurities of the unreacted copper precursor remain Which is undesirable.

Since component iii), as described above, has a property that most of the organic metal salt of component ii) dissolves only in water and does not dissolve in most other solvents, the chemical of component iii) is complexed with a ligand to solve component ii ) ≪ / RTI > solid organic copper salt to a liquid organic precursor. In particular, by applying the chemical of component i) and component iii) as a ligand, the liquid copper organic precursor can have a dissolving power in various organic solvents (alcohol solvents such as isopropyl alcohol and methaneol).

The component iii) can be, for example, an alkanolamine, which is used to convert the organic copper salt of component ii) into a metal (copper) organic precursor so that the unpaired electron pair of amino groups contained in the alkanolamine It is easy to form a coordination bond with a metal (copper) ion so that a solid organic copper salt can be easily converted into a liquid phase and can be easily dispersed in an organic solvent by a hydroxy group not participating in coordination bond after coordination bond.

In addition, in addition to the reaction that the amino group is oxidized to imine and nitrile upon pyrolysis of the copper organic precursor, the oxidation reaction leading to the aldehyde and the carboxylic acid of the primary alcohol contained in the alkanolamine is added, thereby helping reduction of the copper ion can do.

As an example, the alkanolamine refers to an organic compound having a hydroxyl group and an amino functional group in an alkane backbone. Specific examples of the alkanolamines applicable to the present invention include N-methylethanolamine, N-ethylethanolamine, N-propylethanolamine, N-butylethanolamine, diethanolamine, triethanolamine, N-methyldiethanol Amine, N-ethyldiethanolamine, isopropanolamine, diisopropanolamine, triisopropanolamine, N-methylisopropanolamine, N-ethylisopropanolamine, N-propylisopropanolamine, 2-aminopropane- 1-ol, N-methyl-1-aminopropane-3-ol, N-ethyl-1-aminopropan- Aminobutane-2-ol, N-ethyl-1-aminobutan-2-ol, 2-aminobutane- Ol, N-methyl-2-aminobutan-1-ol, N-ethyl- 3-aminobutan-1-ol, 1-aminobutan-4-ol, N-methyl- Amino-2-methylpropan-1-ol, 1-aminopentane-1-ol, 2-amino-4-methylpentan-1-ol, 2-aminohexan-1-ol, 3-aminoheptan- Diol, tris (oxymethyl) aminomethane, 1,2-diaminopropan-3-ol, 1,3-di 2-ol and 2- (2-aminoethoxy) ethanol.

The content of component iii) may be in the range of 10 to 25% by weight, 10 to 21% by weight, or 14 to 25% by weight, based on the total weight of the composition. If the content of the component (iii) is less than 10% by weight, the copper precursor does not completely react as a ligand to cause dispersion and reduction. If the content exceeds 25% by weight, Which is undesirable.

Particularly, the content of the component iii) to be mixed with the organic copper salt of the component ii) can be used in consideration of the number of coordination of the copper ion. For example, the content of the component iii) (Copper) in an equivalent ratio of 1.5 to 2.5 times. In other words, copper has six coordinateable positions. In the case of copper formate, one formate molecule binds to copper atoms in a bidentate form and occupies two coordination sites. Also, since the copper formate contains two formates, it is preferable to add 2 equivalents of the component iii) to the copper because two possible coordination sites remain on the copper metal atom.

That is, the composition for synthesizing the graphite powder having a wide gap according to the present invention is characterized in that a hydroxyl group and an amino functional group are added to the alkane main chain of the component (iii) to provide a ligand forming a copper complex together with the organic copper salt of the component ii) ≪ / RTI > alkanolamine. Specifically, in the composition, a copper complex can be formed which comprises a ligand derived from an alkanolamine having copper as a central metal derived from an organic copper salt and having a hydroxyl group and an amino functional group in the alkane backbone.

The component iv) is graphite to be subjected to copper oxide hybridization, and its content is in the range of 5 to 35% by weight, preferably 6 to 34% by weight, based on the total weight of the composition can do. When the content of the component iv) is less than 5% by weight, there is a problem that the reaction of the graphite as a negative electrode is hardly observed. When the content is more than 35% by weight, the expansion effect of the interlayer spacing of the graphite is poor.

The component iv) used in the present invention includes, for example, artificial graphite obtained from graphitizable carbon such as natural graphite, petroleum coke or coal pitch coke, graphite such as expanded graphite and the like. The shape of the graphite particles may be spherical, fibrous or pulverized products thereof. When the graphite is formed into a negative electrode, the particle diameter of the graphite may be 100 占 퐉 or less.

The composition for synthesizing the graphite powder having a wide gap may further contain additional components in addition to the above-mentioned components depending on the desired properties, and the concrete kinds of the additional components may include, unless they adversely affect the desirable characteristics of the composition There is no particular limitation. If further ingredients are included, the additional additives may be present in an appropriate amount in the composition. For example, an alcohol component may be used as the component v) in the composition. For example, methanol, ethanol, isopropyl alcohol, n-butyl alcohol and the like may be contained as a viscosity controlling agent.

The content of the component v) is not particularly limited, but may be in the range of 1.5 to 5% by weight based on the total weight of the composition so as to control the smooth dispersion and the appropriate viscosity.

Next, a method for producing graphite powder having a wide gap according to the present invention will be described in detail. According to the production method of the present invention, it is possible to easily synthesize a composite of graphite, which is advantageous for a high-performance lithium ion battery anode, and graphite, which has a wide gap, by applying heat to a mixture of a copper ion complex and graphite. , The effect of carbon dioxide gas on graphite can be provided to widen the layer of graphite and this effect provides an advantage of reducing the stress caused when lithium is intercalated into graphite, The copper oxide formed due to the decomposition of lithium can be formed into a high-capacity material while reacting with lithium, thereby providing both the stability of graphite and the high capacity of copper oxide.

Specifically, the manufacturing method according to the present invention includes a step of synthesizing a graphite powder having a wide gap under a reaction condition and a process suitably selected from the composition for synthesizing the above-mentioned graphite powder having a wide gap. Such compositions include aliphatic organic amine solvents; Organic copper salts; Alkanolamines having a hydroxyl group and an amino functional group in the alkane backbone and graphite, the composition of which has been described in detail above.

In one embodiment of the present invention, a method of producing a graphite powder having a wide gap includes a step of heat decomposing the above-mentioned composition under an oxidizing atmosphere. In a specific embodiment of the present invention, a process for producing a graphite powder having a wider spacing of graphite powder, comprising: a) mixing an aliphatic organic amine solvent, an organic copper salt, and an alkanolamine having a hydroxyl group and an amino functional group in an alkane main chain ≪ / RTI > to obtain a liquid metal organic precursor; b) vacuum drying said liquid metal organic precursor to obtain a solid metal organic precursor; c) obtaining a mixture of said solid phase metal organic precursor and graphite; And d) subjecting the mixture to thermal decomposition in an oxidizing atmosphere.

The composition for synthesizing graphite powder used in the reaction of step a) can be obtained by mixing an aliphatic organic amine solvent, an organic copper salt, and an alkanolamine having a hydroxyl group and an amino functional group in an alkane main chain. Here, the specific mixing method is not particularly limited, and may be mixed by an appropriate mixing method in the art, and each of the ingredients may be mixed in a proper mixing order and an appropriate mixing ratio.

The reaction of step a) may be carried out in a temperature range of 50 ° C or higher, preferably in a temperature range of room temperature to 50 ° C, more preferably in a range of 25 ° C to 30 ° C.

The reaction of step b) may be carried out in a time range of 8 hours or more, preferably 8 to 24 hours, more preferably 8 to 15 hours.

The reaction of step b) is not limited thereto, but it is preferable to carry out the reaction under vacuum in consideration of moisture or impurities which may affect the reaction.

Through the reaction of step b) above, a solid phase metal organic precursor is obtained, and then, as step c), graphite is mixed. At this time, it is preferable that the graphite is mixed so that the weight ratio of the copper ion complex and the graphite contained in the solid metal organic precursor is 1: 2 to 1:16. When the amount is less than 1: 2, If the ratio is more than 1:16, the copper ion complex may not sufficiently generate gases such as hydrogen and carbon dioxide during the thermal decomposition in the step (d) described later, or the copper oxide produced by the decomposition of the copper ion complex may have a sufficient content It is not. For reference, the proportion of copper oxide which is in contact with graphite with a copper oxide-coated graphite adherent varies depending on the type of graphite, the particle size, the attachment form of the copper oxide, etc. However, the weight ratio of graphite to copper oxide ranges from 70:30 to 90:10, 70:30 to 97: 3, or 75:25 to 90:10. If the ratio of the weight of the copper oxide component is less than 3, the effect of the copper oxide formed is not remarkable. If it is larger than 70:30, the reaction sites of lithium ions are reduced during charge and discharge of graphite. When assembled as a lithium ion battery , The usable capacity of the battery becomes small, which is not practical.

In addition, the viscosity control agent of component v) described above in step c) may be mixed to improve the degree of dispersion.

The reaction of step d) can be carried out in a temperature range of 350 ° C or higher, preferably in a temperature range of 350 to 1800 ° C, more preferably in a temperature range of 350 ° C to 600 ° C. Can be carried out in the time range of 8 hours or more, preferably in the range of 8 to 24 hours, more preferably in the range of 8 to 15 hours.

In another embodiment of the present invention, a method for producing a wider-spaced graphite powder comprises steps a), b), c) and d) described above, c) and after step d) It is possible to provide an effect of producing a uniform distribution of graphite which is wider than copper ions. There is no particular limitation to the specific method for homogenization, and the homogenization can be carried out under the condition of 500 to 1000 rpm using an appropriate method known in the art, for example, homogenizer which is generally available.

The method for producing a graphite powder with a wide gap according to the present invention may include any additional step as required. For example, the process for producing the graphite powder with a wide gap according to the present invention may further comprise a drying step. There is no particular limitation on this drying method, and it can be carried out by a suitable method known in the art. In addition, the method for producing graphite powder having a wide gap according to the present invention may optionally further include a surface treatment step of graphite powder having a wide gap.

The process for producing a graphite powder having a wide gap according to the present invention is a relatively simple and easy process. In the process of thermal decomposition in an oxidizing atmosphere, copper ions are introduced onto all or a part of the surface of graphite particles capable of intercalating lithium ions. (See the XRD analysis results of FIG. 2 and the Raman spectrum results of FIG. 3) can be synthesized, which is advantageous for producing copper oxide on the surface by decomposing the compound containing the graphite powder, . That is, since the method for producing graphite powder having a wide gap according to the present invention uses a thermal decomposition method based on optimized composition, it is suitable for mass production of graphite powder having relatively simple process, low cost, and wide spacing.

The high quality graphite powder having a wide interval according to the present invention can be used for various electrode materials and can be utilized in various fields such as a lithium ion battery. Accordingly, the high capacity cathode according to the present invention will be described in detail. According to the high capacity anode of the present invention, a copper oxide is produced by decomposing a compound containing copper ion on all or a part of the surface of graphite particles capable of intercalating lithium ions, The negative electrode comprising a graphite composite, a conductive material and a binder, wherein the graphite composite with copper oxide may be the above-described expanded carbon powder.

In graphite as a main component of the negative electrode active material used in the present invention, the intensity ratio of peak near 1360 cm ^-1 to the peak near 1580 cm ^-1 , that is, I _D / I _G value is 0.04 or less by argon laser Raman As shown in FIG. For reference, the widening of the interlayer spacing can be confirmed from the lowered crystallization degree, which can increase the charging / discharging potential, but it has an advantage that it can have more stability when lithium ions enter. Further, it was confirmed from FIG. 2 that the value of I _D / I _{G as} compared to the graphite increases to 0.228 in the case of copper oxide / expanded graphite (corresponding to Example 4) used in the present invention.

As described above, the particle diameter of the copper oxide that is subjected to the composite treatment with graphite in the copper oxide-based graphite composite is preferably at least about 1 μm, and is preferably in the range of not more than the particle diameter of graphite present at the same time.

The contact state between the graphite particles and the copper oxide particles in the copper oxide-based graphite composite of the present invention is such that the copper oxide particles starting to precipitate on the sides of the graphite particles in the mixed state are large while trying to bring carbon, It stops. For reference, the reason why the defect occurs when the particle size of copper oxide is larger than the particle diameter of the graphite present at the same time is that the reaction area decreases with increase of the particle diameter, and the effect of the copper oxide is relatively , And at the same time, the effect of copper oxide is relatively reduced even in the relative comparison of electrode reactivity with graphite.

The ratio of the copper oxide-based graphite composite to the conductive material and the binder material constituting the high capacity anode of the present invention is 60 to 90:10 to 30: 1 to 15 by weight, 60 to 80: 10 to 30: 10, or 60 to 80:10 to 30:10 to 15 in terms of weight ratio, and it is possible to provide excellent conductivity and high binding force effect within this range. The high-capacity cathode may have a capacity characteristic of 600 mAh / g or less, preferably 300 mAh / g or more and 600 mAh / g or less, for example. As a result, it is possible to provide a lithium ion battery including the high capacity cathode.

The negative electrode is formed by mixing a conductive material and a binder together with a composite in contact with copper oxide on all or a part of the surface of the graphite particles shown above. As the conductive material, carbon materials such as carbon black (acetylene black, thermal black, channel black and the like), graphite powder, metal powder, and the like can be used, but not limited thereto. Examples of the binder include acrylic resins such as polyacrylic acid and polyacrylic acid esters, cellulose resins such as ethyl cellulose, cellulose ester and cellulose nitrate, aliphatic or copolymer polyester resins, polyvinyl butyral, polyvinyl acetate, polyvinyl Polyolefin resins such as polyamide resins, polyurethane resins, polyether and urea resins, alkyd resins, silicone resins, fluororesins, olefin resins such as polyethylene and polystyrene, thermoplastic resins such as petroleum resins and rosin resins Based resin, an epoxy resin, an unsaturated or vinyl polyester resin, a diallyl phthalate resin, a phenol resin, an oxetane resin, an oxazine resin, a bismaleimide resin, a silicone epoxy or a silicone poly Modified silicone resins such as esters, melamine-based resins, etc. Can be used together with a butadiene rubber (SBR), natural polymers such as starch, gelatin, select one or more categories - curable resins, acrylic resins of various structures of the ultraviolet ray or electron beam curing type, and ethylene-propylene rubber (EPR), styrene.

In addition to the above-mentioned organic resin binder, an inorganic binder such as glass resin or glass frit, a silane coupling agent such as trimethoxypropyl silane or vinyl triethoxy silane, or a titanium-based, zirconium-based or aluminum- Coupling system can be used.

To collect current from the cathode, a current collector is needed. Examples of the current collector include a metal foil, a metal mesh, and a three-dimensional porous body. As the metal used for the current collector, a metal which is difficult to alloy with lithium is preferable in terms of mechanical strength when the charge-discharge cycle is overlapped. Particularly, iron, nickel, cobalt, copper, titanium, vanadium, chromium, manganese alone or an alloy thereof is preferable.

As the ion conductor, for example, an organic electrolytic solution, a polymer solid electrolyte, an inorganic solid electrolyte, a molten salt and the like can be used. Among them, an organic electrolytic solution is suitably used. The organic electrolytic solution is composed of a solvent and a solute, and the electrolytic solution is adjusted by dissolving the electrolyte in the solvent. Examples of the solvent for the organic electrolytic solution include esters such as propylene carbonate, ethylene carbonate, butylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate and? -Butyrolactone, and substituted tetrahydrofuran such as tetrahydrofuran and 2-methyltetrahydrofuran Ethers such as tetrahydrofuran, dioxolane, diethyl ether, dimethoxyethane, diethoxyethane and methoxyethoxyethane, dimethyl sulfoxide, sulfolane, methyl sulfolane, acetonitrile, methyl formate, And may be used as a mixed solvent of one kind or two or more kinds thereof. Examples of the electrolyte include lithium salts such as lithium perchlorate, lithium borofluoride, lithium fluoride, lithium arsenic fluoride, lithium trifluoromethanesulfonate, lithium halide and lithium aluminate chloride, and one or two of them Or more can be mixed and used. The solvent and the electrolyte used for adjusting the electrolytic solution are not limited to those described above.

Examples of the binder include fluorine-based polymers such as polytetrafluoroethylene and polyvinylidene fluoride; polyolefin-based polymers such as polyethylene and polypropylene; and synthetic rubbers. However, the binder is not limited thereto. This mixing ratio can be set to 99: 1 to 70:30 in terms of the weight ratio of the composite with copper oxide on the surface of all or part of the graphite particles to the binder. If the binder is larger than 70:30, the resistance or polarization of the electrode becomes large and the discharge capacity becomes small, so that a practical lithium ion battery can not be manufactured. Further, if the binder is smaller than 99: 1, only the binding capacity of the electrode can not be maintained, and the production of the battery becomes difficult due to the dropout of the active material and the lowering of the mechanical strength. In the production of the negative electrode, in order to improve the binding property, it is preferable to carry out heat treatment at a temperature before and after the melting point of each binder.

Examples of the positive electrode of the lithium ion battery of the present invention include LiCoO ₂ , LiNiO ₂ or LixMyNzO ₂ (where M is one of Fe, Co, and Ni, and N is a transition metal, a 4B group, or a 5B group metal) , LiMn ₂ O _4, and LiMn _{2 - x} NyO ₄ (where N represents a metal of a transition metal, a 4B or 5B group) as a positive electrode active material, and a conductive material, A solid electrolyte or the like is mixed according to the above.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a composition for synthesizing graphite powder having a wide gap according to the present invention, a method for producing graphite powder having a wide gap using the same, and a high capacity cathode and a lithium ion battery using the same will be described in detail. But is not limited thereto.

[Example]

Example  One

The production of graphite powder with a wide gap was performed according to the process flow chart of Fig. 1, as step a), n-octylamine is used as the aliphatic organic amine solvent of component i), copper formate tetrahydrate as the organic copper salt of component ii), and the alkane backbone of component iii) 2-amino-2-methylpropan-1-ol was prepared as an alkanolamine having a carboxyl group and an amino functional group. 11.45 g of component i) and 8.97 g of component iii) were added to 20 g of the component ii) and mixed for 30 minutes to carry out the complexation reaction to obtain a liquid metal organic precursor.

Subsequently, as the step b), the liquid metal organic precursor was kept at 50 캜 in a vacuum state and then dried for 8 hours or longer to obtain 15 g of a solid metal organic precursor (copper ion complex). At this time, unreacted components were removed.

The thus prepared solid phase metal organic precursor (copper ion complex) is dispersed in isopropyl alcohol (IPA) as a viscosity controlling agent in step c), and graphite (artificial graphite, particle diameter 20 to 100 탆) Graphite = 1: 2) to obtain a mixture of graphite and copper ion complex.

As the step c) and the subsequent step d), a homogenization process of mixing a mixture of the copper ion complex and graphite for 10 minutes or more was carried out using a homogenizer.

Then, as step d), the mixture of the copper ion complex and the graphite was heated and decomposed at 350 ° C or higher in an oxygen atmosphere to be maintained for at least 8 hours to be thoroughly dried, and then obtained as a graphite powder with a wide spacing.

XRD analysis and Raman spectrum analysis were performed on the graphite powder and the untreated graphite having the above-mentioned intervals, and the results are shown in FIG. 2 and FIG. 3, respectively. FIG. 2 is a graph comparing the physical properties of graphite powder (Example 4) having a wide gap obtained according to an embodiment of the present invention and untreated graphite powder according to Raman Spectroscopy (Renishaw) FIG. 3 is a graph comparing the physical properties of graphite powder and untreated graphite powder obtained according to an embodiment of the present invention in accordance with an X-ray diffractometer (Bruker / New DB Advance).

2, the graphite as a main component of the negative electrode active material had an intensity ratio of a peak near 1360 cm ^-1 to the peak near 1580 cm ^-1 , that is, an I _D / I _G value of 0.04 or less by argon laser Raman , It was confirmed that the value of I _D / I _{G as} compared with graphite increased to 0.228 in case of Example 4 as copper oxide / expanded graphite.

3, diffraction lines derived from graphite and diffraction lines derived from cupric oxide were observed, and it was found that graphite and cupric oxide were observed. More specifically, as shown in Fig. 3, (2? = 35.8, 38.9, 61.6, 66.3, 68.1 degrees), cuprous oxide (2? = 36.4 degrees) and graphite (2? = 24.8, 42.2, 44.4, 54.6 degrees).

Example  2

The graphite (artificial graphite, particle diameter 20 to 100 탆) was dispersed in isopropyl alcohol (IPA) as a viscosity modifier in step c) in the same manner as in Example 1, except that the solid metal organic precursor (copper ion complex) : 4 in terms of weight ratio.

Example  3

The graphite (artificial graphite, particle diameter 20 to 100 탆) was dispersed in isopropyl alcohol (IPA) as a viscosity modifier in step c) in the same manner as in Example 1, except that the solid metal organic precursor (copper ion complex) : ≪ / RTI > 8 by weight.

Example 4

The graphite (artificial graphite, particle diameter 20 to 100 탆) was dispersed in isopropyl alcohol (IPA) as a viscosity modifier in step c) in the same manner as in Example 1, except that the solid metal organic precursor (copper ion complex) : ≪ / RTI > 16 by weight, the same procedure as in Example 1 was repeated.

Experimental Example

In order to evaluate the performance of the lithium ion battery coin cell fabricated in Example 1, an electrode was manufactured by using graphite powder and untreated graphite of Examples 1 to 4 having a wide gap as the active material.

Carbon black, which is a conductive material, and a mixture of styrene-butadiene (SBR) and carboxymethyl cellulose (CMC) in a ratio of 1: 1 were used for the purpose of imparting electrical conductivity to the electrode. Here, the polymer binder was dissolved in distilled water, and the graphite powder, the conductive material and the binder having the wide intervals of Example 1 were mixed at a weight ratio of 60:30:10, sufficiently stirred, then coated with a copper collector, Moisture was removed by drying for more than 8 hours.

A lithium ion battery was fabricated in a glove box of argon atmosphere in a 2032 size coin cell using the electrode thus fabricated. (LiPF6) / ethylene carbonate (EC): dimethyl carbonate (DMC): diethyl carbonate (DEC) (volume ratio of 1: 1: 1 by volume) as an electrolyte was used as a counter electrode. ) Was used to fabricate an electrochemical cell.

In order to evaluate the performance of the lithium ion battery coin cell fabricated in this manner, charge / discharge test (using WonSech's WBCS 3000L) was conducted. As shown in FIG. 4, it was confirmed that the capacity was changed by addition of the copper ion complex, and the best results were obtained when the graphite / copper oxide ratio of Example 4 was 1:16.

Further, charging and discharging tests were carried out at 0.2, 1, 20, and 60 cycles, respectively, on the basis of the material. As a result, as shown in Fig. 5, it was confirmed that the battery had a voltage flat part caused by each material. As a result of comparing the capacities per active material weight of the electrode, the untreated graphite (FIG. 5B) showed a capacity of about 300 mAh / g similar to the theoretical capacity (372 mAh / g), while the graphite powder In the case of the electrode using the electrode (FIG. 5A), the capacity was 530 mAh / g.

Comparative Example 1

As a result of an experiment in which the n-octylamine of component i) in Example 1 was replaced with an aliphatic organic amine having 20 carbon atoms, it was confirmed that the decomposition temperature of the copper ion complex increased and the formation of copper oxide became unstable and a large amount of impurities remained. The preparation of the electrode was also not appropriate.

Comparative Example 2

As a result of replacing the copper formate tetrahydrate, which is an organic copper salt in Example 1, with an inorganic copper salt such as copper sulfate or copper nitrate, it was confirmed that formation of the copper ion complex of step (a) There was no.

Comparative Example  3

In the step (d) of Example 1, heating was carried out in an oxidizing atmosphere, and at a heating temperature of 330 ° C, it was confirmed that a powder in which copper and copper oxide were simultaneously mixed was formed. The preparation of the electrode was also not appropriate.

Claims (18)

A composition for synthesizing a graphite powder having a wide gap,
i) an aliphatic organic amine solvent,
ii) organic copper salts,
iii) an alkanolamine having a hydroxyl group and an amino functional group in the alkane main chain, and
iv) a composition comprising graphite. The method according to claim 1,
In which the components i), ii) and iii) are present in the form of copper complexes, wherein the copper complexes contain copper derived from component ii) as the central metal and ligands derived from component i) and component iii) / RTI > The method according to claim 1,
Wherein component i) is a primary amine including propylamine, n-butylamine, hexylamine, octylamine; Secondary amines including diisopropylamine, di (n-butyl) amine; Tertiary amines including trioctylamine, tri-n-butylamine; Or an aliphatic organic amine of an alkylamine, including ethylamine, propylamine, butylamine, trioctylamine. The method according to claim 1,
Wherein component ii) is selected from the group consisting of acetate, citrate ≪ / RTI > and formate. The method according to claim 1,
Wherein component iii) is selected from the group consisting of N-methylethanolamine, N-ethylethanolamine, N-propylethanolamine, N-butylethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, Amines, diisopropanolamine, triisopropanolamine, N-methylisopropanolamine, N-ethylisopropanolamine, N-propylisopropanolamine, 2-aminopropane- Ol, N-methyl-1-aminopropan-3-ol, N-ethyl-1-aminopropane- 2-ol, N-methyl-1-aminobutan-2-ol, N-ethyl-1-aminobutan- 3-aminobutane-1-ol, N-ethyl-3-aminobutane-1-ol, Ol, 1-aminobutan-4-ol, N-methyl-1-aminobutan- Ol, 2-amino-4-methylpentan-1-ol, 2-aminohexan-1-ol 4-ol, 1-aminopropane-2,3-diol, 2-aminopropane-1,3-diol, At least one alkane backbone selected from tris (oxymethyl) aminomethane, 1,2-diaminopropane-3-ol, 1,3-diaminopropane- Is an alkanolamine having a hydroxyl group and an amino functional group. The method according to claim 1,
The alkanolamine having a hydroxyl group and an amino functional group in the main chain of the alkane is used in an amount of 10 to 30% by weight based on the total weight of the composition, 10 to 30% by weight of the aliphatic organic amine solvent, 30 to 50% 25 wt%, and the graphite in an amount of 5 to 35 wt%. The method according to claim 1,
Wherein the composition comprises at least one viscosity modifier selected from the group consisting of isopropyl alcohol, methanol, ethanol and n-butyl alcohol as component v). A process for producing graphite, which comprises subjecting a composition according to any one of claims 1 to 7 under an oxidizing atmosphere to decompose a compound containing copper ions on all or part of the surface of the graphite particles, A method for synthesizing a powder. 9. The method of claim 8,
The method
a) mixing and reacting an aliphatic organic amine solvent, an organic copper salt and an alkanolamine having a hydroxyl group and an amino functional group in an alkane main chain to obtain a liquid metal organic precursor;
b) vacuum drying said liquid metal organic precursor to obtain a solid metal organic precursor;
c) obtaining a mixture of said solid phase metal organic precursor and graphite; And
and d) heating and decomposing the mixture in an oxidizing atmosphere. 10. The method of claim 9,
Wherein step (a) is carried out under vacuum for at least 8 hours at a temperature of at least < RTI ID = 0.0 > 50 C. < / RTI > 10. The method of claim 9,
Wherein the viscosity adjusting agent is mixed in step c). 10. The method of claim 9,
Further comprising a homogenization step after step c) and before step d). 10. The method of claim 9,
Wherein step d) is carried out in an oxidizing atmosphere at a temperature of 350 DEG C or more for 8 hours or more. A method for producing copper oxide on a surface by decomposing a compound containing copper ion on all or a part of the surface of an insert deintercalation-capable graphite particle of lithium ion, As a negative electrode,
Wherein the copper oxide-based graphite composite is the expanded carbon powder according to any one of claims 1 to 7. 15. The method of claim 14,
Wherein the ratio of the copper oxide which is in contact with the graphite as the graphite composite with copper oxide is 70:30 to 90:10 by weight of graphite and copper oxide. 15. The method of claim 14,
A high capacity cathode having a weight ratio of 60 to 90:10 to 30:10 to 15 of a copper oxide-based graphite composite constituting the negative electrode, a conductive material and a binder. 15. The method of claim 14,
Wherein the high capacity cathode has a capacity characteristic of 600 mAh / g or less. A lithium ion battery comprising a high capacity cathode according to claim 14.

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