JP2001035481A - Battery having uniformly doped electrode and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the battery capacity retainability, discharge time and battery clone efficiency by comprising a current collector substrate, an electrode active material having a crystal structure, and a dopant substantially uniformly contained in the crystal structure. SOLUTION: This battery 10 is formed of a first electrode 12, a second electrode 14 and an electrolyte 16. The second electrode 14 is formed of an active material layer 17 and a current collector 20, and it contains an active material component 18 retained by a binder and applied to the current collector 20. The active material component 18 is formed of a transition metal oxide or a lithium transition metal oxide such as LiMnO4, LiCoO2, or LiNiO2, and a particularly preferable one is a crystal consisting of a lithium nickel oxide having α-NaFeO2 type structure represented by LiNiO2. A dopant uniformly contained in the crystal lattice of the active material component 18. As the dopant, alkali metal, rare earth metal or gallium is used, and gallium is particularly preferred.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery, and more particularly, to a battery having an electrode in which a dopant is substantially uniformly contained in a crystal structure of an electrode active material. The present invention also relates to a method for producing the battery. In particular, the present invention
The present invention relates to an electrode for a lithium ion battery and a method for manufacturing the same.

[0002]

2. Description of the Related Art Lithium-based electrochemical batteries (lithium ion batteries) are already known. Further, experimental research on the doping of an active material into an internally added electrode used in a lithium-based battery has been advanced. Batteries using "doped" electrodes exhibit some promising electrochemical properties,
In particular, there were still problems regarding battery capacity retention, battery discharge time, and battery coulomb efficiency. One of the causes of this problem is considered to be the non-uniform addition of the dopant into the electrode active material lattice.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a battery in which a dopant is uniformly added into an electrode active material lattice, thereby improving battery capacity retention, battery discharge time and battery coulomb efficiency. It is.

[0004]

The present inventors have conducted intensive studies to achieve the above object, and as a result, by using a specific method, a dopant can be uniformly added to the electrode active material lattice. Finding that the problem can be solved,
The present invention has been completed.

The present invention has been completed based on the above findings, and a first gist of the present invention is to provide a current collector substrate, an electrode active material having a crystal structure, and a crystal structure of the electrode active material. The present invention resides in a battery electrode comprising a uniformly contained dopant.

A second aspect of the present invention resides in an electrode according to the first aspect, wherein the dopant is selected from the group consisting of alkali metals, rare earth metals, gallium, and mixtures thereof.

[0007] A third aspect of the present invention resides in an electrode according to the second aspect, wherein the dopant is gallium.

According to a fourth aspect of the present invention, there is provided any one of the first to third aspects, wherein the electrode active material is selected from the group consisting of transition metal oxides, lithium transition metal oxides, and mixtures thereof. Exists on the electrodes.

A fifth aspect of the present invention resides in an electrode according to the fourth aspect, wherein the lithium transition metal oxide is selected from the group consisting of LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ and a mixture thereof. .

A sixth aspect of the present invention resides in the electrode according to any one of the first to fifth aspects, wherein the particle size of the electrode active material is 50 μm or less.

A seventh aspect of the present invention resides in the electrode according to any one of the first to sixth aspects, wherein the particle diameter of the electrode active material is in a range of 1 to 10 μm.

According to an eighth aspect of the present invention, there is provided a battery comprising an electrolyte, a first electrode and a second electrode, wherein at least one of the first and second electrodes comprises one of the first to seventh aspects. The present invention relates to a battery which is the electrode described in (1).

A ninth aspect of the present invention includes a step of forming a first electrode; a step of forming a second electrode; and a step of associating at least one type of electrolyte with the first and second electrodes. Wherein the first electrode forming step includes a step of forming a current collector substrate; a step of preparing an electrode active material layer having a crystal structure containing a dopant uniformly; and a current collector. Applying the doped electrode active material layer to a substrate.

A tenth aspect of the present invention is that the doped electrode active material layer preparing step comprises dissolving an alkali metal acetate, a rare earth metal salt or a gallium metal acetate, and a polymer component in a substantially polar solvent, Producing a gelatinous substance; mixing the gelatinous substance; removing the substantially polar solvent from the resulting solution to obtain a substantially dry substance; A method according to the ninth aspect, comprising a step of decomposing and a step of uniformly pulverizing the pyrolyzed substance.

An eleventh aspect of the present invention provides (1) a step of dissolving a transition metal salt and at least one compound selected from a rare earth metal salt and a gallium salt in a solvent;
(2) a step of obtaining, from the obtained solution, a uniform product containing a transition metal element and at least one element selected from rare earth metals and gallium; and (3) heating the obtained uniform product. And the electrode active material for a battery obtained through the step of treating.

A twelfth aspect of the present invention is that (1) a gelatinous substance obtained by dissolving a transition metal salt and at least one compound selected from a rare earth metal salt and a gallium salt together with a polymer component in a solvent. (2) removing the solvent from the obtained gelatinous substance to obtain a dry substance; and (3) heat-treating the obtained dry substance for a battery. Exists in the electrode active material.

A thirteenth aspect of the present invention is that (1) a step of dissolving a transition metal salt and at least one compound selected from a rare earth metal salt and a gallium salt in a solvent;
(2) a step of obtaining, from the obtained solution, a uniform product containing a transition metal element and at least one element selected from rare earth metals and gallium; and (3) heating the obtained uniform product. And a step of treating the battery.

According to a fourteenth aspect of the present invention, (1) a gelatinous substance is prepared by dissolving a transition metal salt and at least one compound selected from a rare earth metal salt and a gallium salt together with a polymer component in a solvent. An electrode comprising: (2) removing the solvent from the obtained gelatinous substance to obtain a dry substance; and (3) heat-treating the obtained dry substance. Active manufacturing method.

According to a fifteenth aspect of the present invention, in the step (1), a thirteenth aspect further comprising an alkali metal salt in a solution.
Or the method for producing an electrode active material described in the summary of item 14.

A sixteenth aspect of the present invention is (1) a step of dissolving a lithium salt, a nickel salt and a gallium salt together with a polymer component in a solvent to produce a gelatinous substance;
(2) A method for producing an electrode active material, comprising: a step of obtaining a dry substance by removing the solvent from the obtained gelatinous substance; and (3) a step of heat-treating the obtained dry substance.

According to a seventeenth aspect of the present invention, an electrode active material comprises:
A sixteenth aspect of the present invention provides the method for producing an electrode active material having an α-NaFeO ₂ type structure.

An eighteenth aspect of the present invention resides in the method for producing a battery electrode according to any one of the thirteenth to seventeenth aspects, further comprising a step of pulverizing the product after the heat treatment.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. The present invention is not limited to the embodiments and descriptions illustrated below, as the invention is capable of various embodiments.

FIG. 1 is a schematic view showing one embodiment of a battery manufactured according to the present invention. The battery 10 of the present invention
It comprises an electrode 12, a second electrode 14, and an electrolyte 16. The first electrode 12 is preferably made of lithium, carbon, or a mixture of lithium and carbon. Second electrode 14
Usually comprises an active material layer 17 and a current collector 20, and includes an active material component 18 held by a binder (not shown) and applied to the current collector 20. The active material component 18 includes a transition metal oxide, LiMnO ₄ , LiCoO _2, or LiNiO ₂
And the like. In that the effect of the present invention is particularly remarkable, an active material preferably used in the present invention is represented by LiCoO ₂ or LiNiO ₂ ,
It is a crystal having an α-NaFeO ₂ type structure. Particularly preferred is a crystal composed of lithium nickel oxide having an α-NaFeO ₂ type structure represented by LiNiO ₂ . Although not shown, the dopant is uniformly contained in the crystal lattice of the active material component. As described in detail below, by uniformly including the dopant in the crystal lattice of the active material component, the capacity retention, discharge life, and Coulomb efficiency of the battery are improved.

The dopant is preferably an alkali metal, a rare earth metal or gallium. As the alkali metal, lithium, sodium and potassium are preferable, and sodium and potassium are particularly preferable. As used herein, the term "rare earth metal" refers collectively to Group III elements and lanthanide elements. As the rare earth metal, cerium, erbium, and gadolinium are preferable. Particularly preferred dopants are rare earth metals or gallium, of which gallium is preferred. The amount of the dope is usually 0.001% by weight or more, and preferably 0.01% by weight or
It is at least 1% by weight, and usually at most 10%, preferably at most 5%. When a lithium transition metal oxide is used as the electrode active material, the doping amount is usually 0.0% with respect to the transition metal constituting the lithium transition metal oxide.
It is at least 01 at%, preferably at least 0.01 at%, and usually at most 10 at%, preferably at most 5 at%. If the doping amount is too small, the effect may be insufficient, while if it is too large, the capacity tends to decrease.
For example, using LiNiO ₂ as the active material, when using gallium as a dopant, as described in the examples below, is doped by structure such as LiNi _x Ga _y O _2. Here, x is 0.8 to 1.2, preferably 0.9 to 1.1, and y is 0.001 to 0.1, preferably 0.001 to 0.05.

The electrolyte 16 may be comprised of conventionally used solvents and salts or electrochemical systems (such as liquid, polymer, gel and plastic systems). As the solvent, propylene carbonate (PC) or ethylene carbonate (E
C) and the like. Examples of the salt include LiPF ₆ or LAs.
F _6, and the like.

Next, a method for manufacturing the battery 10 of the present invention will be described. First, the electrodes 12 and 14 are manufactured. For example, the electrode 12 may be an anode, and the electrode 14 may be formed from an active material layer-containing cathode applied to a current collector substrate. In other battery configurations, the anode and cathode are interchangeable, depending on whether the battery is in a charged or discharged state. Electrode 12 can be formed by conventional techniques.

The electrode active material 18 is preferably a composite oxide of an alkali metal and a transition metal. The composite oxide of an alkali metal and a transition metal can be obtained by the method for producing an electrode active material of the present invention.

The electrode active material comprises: (1) a transition metal salt such as at least one selected from nickel salts, manganese salts and cobalt salts, and at least one compound selected from rare earth metal salts and gallium salts. Dissolving in a solvent; and (2) from the obtained solution, a transition metal element such as at least one element selected from nickel, manganese and cobalt, and at least one selected from rare earth metals and gallium. It can be obtained through a step of obtaining a uniform product containing one kind of element and (3) a step of heat-treating the obtained uniform product.

A nickel salt used in step (1),
Salts such as transition metal salts such as manganese salts and cobalt salts, rare earth metal salts and gallium salts include, for example, acetates, nitrates and alkoxides. Nitrate can act as a strong oxidizing agent to produce nitrogen oxides, preferably acetates and alkoxides, most preferably acetates. Examples of the solvent include alcohols such as methanol and ethanol, and various polar solvents such as water.

In the solution of step (1), an alkali metal salt, preferably a lithium salt, is further dissolved.
This is preferable because the process can be simplified and the battery performance can be improved. Further, in order to obtain a uniform product in the subsequent step (2), the solution can be made into a gelatinous substance by allowing a polymer component such as polyvinyl alcohol to be present in the solution.

In order to obtain a homogeneous product in the step (2), for example, a method in which the gelatinous substance is formed in the step (1) and the solvent is removed from the gelatinous substance,
A method of increasing the pH by a method such as adding an alkali agent to the solution obtained in the step (1) and coprecipitating the solution can be mentioned. In order to obtain a dry substance by removing the solvent in the former method, the gelatinous substance may be heated and / or reduced in pressure to evaporate the solvent. In the latter method, for example, a coprecipitate can be obtained by using an alkoxide as a salt and heating the solution in the presence of an alkali.

In the step (3), the obtained homogeneous product is subjected to a heat treatment. The temperature at this time is usually 80 to 100
0 ° C., preferably about 150 to 900 ° C. The processing time is usually 0.5 to 100 hours, preferably 1 to 5 hours.
It is about 0 hours. In the case where the gelatinous substance is obtained in the step (1) and the dried substance obtained by drying the gelatinous substance in the step (2) is subjected to a heat treatment, the heat treatment includes a step of carbonizing the polymer component and the like.

The product obtained by the heat treatment becomes a desired electrode active material by further reaction and post-treatment if necessary. For example, when the lithium salt is dissolved in the solution in the step (1), the same composition as the lithium transition metal oxide can be obtained in the step (3). Further, it is preferable that this is further pulverized to control the particle size. For the pulverization, any of wet pulverization and dry pulverization can be employed. In the case where no lithium salt was present in the above steps (1) to (3), the product obtained in the step (3) was further mixed with a lithium compound such as lithium carbonate or lithium hydroxide, and this was fired. By doing so, a lithium transition metal oxide can be obtained. Also in this case, the particle size can be controlled by a pulverizing process thereafter.

In a particularly preferred embodiment of the above steps, (1) an alkali metal salt, a transition metal salt and at least one compound selected from a rare earth metal salt and a gallium salt are mixed with a polymer component in a solvent. (2) removing the solvent from the obtained gelatinous substance to obtain a dry substance; (3)
Further preferred embodiments of the method for producing an electrode active material and an electrode having a step of heat-treating the obtained dried substance are further described below.

First, an alkali metal acetate, a rare earth metal acetate or a gallium metal acetate is dissolved in a substantially polar solvent. As the alkali metal acetate, lithium acetate, sodium acetate and potassium acetate are preferred. As the rare earth metal acetate, cerium acetate, erbium acetate, and gadolinium acetate are preferable.

As the polar solvent, known solvents can be used.
Water, methanol and ethanol are preferably used.
As the salt, an acetate is preferably used in the present invention.
The reason for this is that the conventionally used nitrate is a strong oxidizer and easily decomposes to generate a large amount of NOx gas. Therefore, explosion, corrosion and environmental problems occur when nitrates are used. On the other hand, when the above-mentioned acetate is used, such a gas is not generated at the time of decomposition.

Next, the polymer component is dissolved in a solvent, and the resulting solution is thoroughly mixed (about 24 hours). As a polymer component, usually, if it has solubility in a solvent,
Although there is no particular limitation, polyvinyl alcohol (PVA) is preferably used. At this point, a substantially clear gelatinous / sol-gel material is formed. In this way, the acetate as the dopant is uniformly contained in the crystal lattice of the active material component.

Next, the solvent is removed under ambient conditions or under reduced pressure. After removal of the solvent, the resulting substantially dry powder / material is placed in a container such as a quartz tube and heat treated in air. The heat treatment preferably includes a first step of carbonizing the polymer component and the like and a second step of generating a composite oxide of an alkali metal and a transition metal. The first step is usually performed at a temperature of 80 to 600 ° C., preferably 100 to 5 ° C.
At about 00 ° C., usually 0.1 to 20 hours, preferably 1 to
Heat treatment for about 10 hours. The subsequent process is usually performed at a temperature of 2
The heat treatment is carried out at a temperature of 00 to 1000 ° C, preferably about 450 to 850 ° C, usually for about 0.1 to 30 hours, preferably for about 1 to 20 hours. All of the steps can be performed in an oxygen-containing gas atmosphere such as air.

As a specific example, first, in air at 200 ° C.
And heat for 2 hours. Subsequently, the temperature is raised to 400 ° C. and maintained for 1 hour (in air). Next, pure oxygen is introduced into the system at a flow rate of 100 ml / min for 30 minutes, and thereafter the flow rate is increased to 300 ml / min. Raise the temperature to 750 ° C. and hold for 16 hours.

The obtained product is preferably obtained by using ceramic beads (polishing medium) and a ball mill roller.
Particle size is usually less than 50 microns, preferably from about 1 to about 10
The material is ground uniformly until it is in the micron range.
After pulverization, if necessary, a carbonaceous additive is added to the obtained substance, and then applied onto a current collector substrate to form a second substance.
The electrode 14 is completed.

Finally, the electrolyte 16 is applied to the electrodes 12 and 14
Associated with each of the Electrolyte 16 can be manufactured using conventional techniques and is typically formed from a salt such as LiPF ₆ or LiAsF ₆ dissolved in at least one solvent such as PC or EC.

The above description is merely an example, and various modifications can be made without departing from the spirit of the present invention.

Hereinafter, as an example of the above change, a configuration of a lithium ion battery preferably used as a battery will be described.

A lithium ion battery usually includes first and second electrodes corresponding to a positive electrode and a negative electrode, and an electrolyte layer interposed therebetween. The first electrode and the second electrode are generally formed by binding an active material on a current collector substrate.

Current collector substrate: As a material of the current collector substrate,
Examples include various metals such as copper, aluminum, nickel, and stainless steel, and alloys thereof. Preferably,
Aluminum is used as the current collector substrate of the positive electrode, and copper is used as the current collector substrate of the negative electrode.

The thickness of the current collector substrate is appropriately selected, but is preferably 1 to 30 μm, more preferably 1 to 20 μm. If it is too thin, the mechanical strength tends to be weak, which is a problem in production. If it is too thick, the capacity of the battery as a whole decreases.

The surface of the current collector substrate is preferably subjected to a roughening treatment in advance, since the adhesive strength of the electrode material is increased. Examples of the surface roughening method include a mechanical polishing method, an electrolytic polishing method, and a chemical polishing method. As a mechanical polishing method,
A method in which the surface of the current collector is polished with a polishing cloth paper to which the abrasive particles are fixed, a grindstone, an emery buff, a wire brush provided with a steel wire, or the like. Further, an intermediate layer may be formed on the surface of the current collector to increase the adhesive strength and the conductivity.

Further, the shape of the current collector substrate may be a plate shape other than the metal mesh.

Active material: The active material used for the first electrode or the second electrode may be appropriately selected according to the type and characteristics of the battery to be manufactured.

In the case of a lithium ion battery, an inorganic compound or an organic compound can be used as the positive electrode active material as long as lithium ions can be inserted and extracted. Examples of the inorganic compound include a transition metal oxide, a composite oxide of lithium and a transition metal, and a chalcogen compound such as a transition metal sulfide. Here, Fe, Co, Ni, Mn, or the like is used as the transition metal. Specifically, MnO, V ₂ O ₅ , V
Transition metal oxides such as ₆ O ₁₃ and TiO ₂ ; composite oxides of lithium and transition metals such as lithium nickelate, lithium cobaltate and lithium manganate; TiS ₂ , FeS;
Transition metal sulfides such as MoS ₂ are exemplified. These compounds may be partially substituted with elements in order to improve their properties. Examples of the organic compound include polyaniline, polypyrrole, polyacene, disulfide-based compounds, and polysulfide-based compounds. These inorganic compounds and organic compounds may be mixed and used as the positive electrode active material. Preferably, it is a lithium transition metal oxide, especially a composite oxide of lithium and at least one transition metal selected from the group consisting of cobalt, nickel and manganese. As described above, the most preferable are LiNiO ₂ , LiCoO ₂ , and LiMn ₂ O ₄ , and particularly α-LiN, represented by LiCoO ₂ and LiNiO _2.
It has a NaFeO ₂ type structure.

The particle size of the positive electrode active material may be appropriately selected depending on the balance with other components of the battery.
The thickness is preferably from 50 to 50, particularly from 1 to 30 μm, and more preferably from 1 to 10 μm, since battery characteristics such as initial efficiency and cycle characteristics are improved.

Examples of the negative electrode active material capable of inserting and extracting lithium ions that can be used for the negative electrode include carbonaceous particles such as graphite and coke. Such a carbon-based material can also be used in the form of a mixture or coating with a metal, metal salt, oxide, or the like. Examples of the negative electrode active material include oxides and sulfates of silicon, tin, zinc, manganese, iron, nickel and the like, metallic lithium, Li-Al, Li
Lithium alloys such as -Bi-Cd and Li-Sn-Cd, lithium transition metal nitrides, silicon and the like can also be used. The average particle size of the negative electrode active material is usually 50 μm or less, preferably 30 μm or less, and more preferably 10 μm or less, from the viewpoint of improving battery characteristics such as initial efficiency, late characteristics and cycle characteristics.
m or less. If the particle size is too large, the electron conductivity deteriorates. Further, it is usually 0.5 μm or more, preferably 1 μm.
m or more.

Other Structures of Electrodes: In order to bind the active material on the current collector substrate, it is preferable to use a binder. As the binder, inorganic compounds such as silicate and glass, and various resins mainly composed of polymers can be used.

Examples of the resin include alkane-based polymers such as polyethylene, polypropylene and poly-1,1-dimethylethylene; unsaturated polymers such as polybutadiene and polyisoprene; polystyrene, polymethylstyrene, polyvinylpyridine and poly-N -Polymers having a ring such as vinylpyrrolidone; acrylic polymers such as polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, polymethyl acrylate, polyethyl acrylate, polyacrylic acid, polymethacrylic acid and polyacrylamide Fluorinated resins such as polyvinyl fluoride, polyvinylidene fluoride and polytetrafluoroethylene; CN group-containing polymers such as polyacrylonitrile and polyvinylidene cyanide; polyvinyl acetate, polyvinyl alcohol, etc. Polyvinyl chloride, halogen-containing polymers such as polyvinylidene chloride; a conductive polymer such as polyaniline can be used polyvinyl alcohol-based polymer. Further, a mixture of the above-mentioned polymers and the like, a modified product, a derivative, a random copolymer, an alternating copolymer, a graft copolymer, a block copolymer and the like can also be used.

The compounding amount of the binder with respect to 100 parts by weight of the active material is preferably 0.1 to 30 parts by weight, more preferably 1 to 15 parts by weight. If the amount of the resin is too small, the strength of the electrode may decrease. If the amount of the resin is too large, the capacity may decrease, or the late characteristics may decrease.

The electrode may contain additives, such as a conductive material and a reinforcing material, which exhibit various functions, a powder, a filler, and the like, if necessary. The conductive material is not particularly limited as long as it can impart conductivity by mixing an appropriate amount with the active material, but usually, acetylene black, carbon black, carbon powder such as graphite, and various metal fibers,
Foil and the like. As additives, trifluoropropylene carbonate, vinylene carbonate, 1,6-
Dioxaspiro [4,4] nonane-2,7
-Dione, 12-crown-4-ether and the like can be used to increase the stability and life of the battery. As the reinforcing material, various inorganic or organic spherical or fibrous fillers can be used.

As a method of forming the electrodes on the current collector substrate, for example, a method in which a powdery active material is mixed with a solvent together with a binder and dispersed and coated with a ball mill, a sand mill, a twin-screw kneader or the like is used. Is preferably applied to a current collector substrate and dried. In this case, the type of the solvent used is not particularly limited as long as it is inert to the electrode material and can dissolve the binder, and for example, a commonly used inorganic or organic solvent such as N-methylpyrrolidone. Can be used.

Alternatively, the active material layer may be formed by a method of pressing or spraying the active material on a current collector substrate in a state where the active material is mixed with a binder and softened by heating. Further, it can be formed by firing the active material alone on the current collector substrate.

The thickness of the active material layer is usually at least 1 μm, preferably at least 10 μm. In addition, usually 200
μm or less, preferably 150 μm or less. If it is too thin, it becomes difficult to ensure uniformity of the active material layer, and the capacity tends to decrease. On the other hand, if the thickness is too large, the rate characteristics tend to decrease.

A primer layer can be provided between the current collector substrate and the active material layer. As a result, the adhesiveness between the current collecting substrate and the active material layer can be further improved. The primer layer can be formed by applying a paint containing a conductive material, a binder, and a solvent on a current collecting substrate and then drying the paint.

As the conductive material used for the primer layer, various materials such as carbonaceous particles such as carbon black and graphite, metal powders, and conductive polymers can be used. The same binder and solvent as those used for the active material layer can be used for the primer layer. The thickness of the primer layer is usually 0.05 μm or more, preferably 0.1 μm or more.
μm or more, and usually 20 μm or less, preferably 1 μm or less.
0 μm or less. If it is too thin, it tends to be difficult to ensure uniformity of the primer layer. If the thickness is too large, the capacity rate characteristics of the battery tend to decrease.

Electrolyte: The electrolyte interacts with the first and second electrodes and participates in ion transfer between the electrodes. The electrolyte usually exists as an electrolyte layer between the electrodes and also exists in the active material layer, and comes into contact with at least a part of the surface of the active material.

The electrolyte generally includes various electrolytes such as an electrolyte having fluidity and a non-fluid electrolyte such as a gel electrolyte and a completely solid electrolyte. An electrolyte or a gel electrolyte is preferable in terms of battery characteristics, and a non-fluid electrolyte is preferable in terms of safety. In particular, when a non-fluid electrolyte is used, liquid leakage can be more effectively prevented for a battery using a conventional electrolyte. Further, in the present invention, since the packaging material is extremely thin, leakage of the electrolyte solution is likely to occur, and in that respect, the effect of using the non-fluid electrolyte is great.

The electrolytic solution used as the electrolyte is usually obtained by dissolving a supporting electrolyte in a non-aqueous solvent.

As the supporting electrolyte, any non-aqueous substance which is stable to the positive electrode and the negative electrode as an electrolyte and which can move for the lithium ion to undergo an electrochemical reaction with the positive electrode active material or the negative electrode active material can be used. Can also be used. Specifically, LiPF ₆ , Li
AsF ₆ , LiSbF ₆ , LiBF ₄ , LiClO ₄ , Li
I, LiBr, LiCl, LiAlCl, LiHF ₂ ,
Lithium salts such as LiSCN and LiSO ₃ CF ₂ are exemplified. Among them, LiPF ₆ and LiClO ₄ are particularly preferable.

When these supporting electrolytes are used in the state of being dissolved in a non-aqueous solvent, the concentration is generally 0.5 to 2.5 m
ol / L. The nonaqueous solvent in which these supporting electrolytes are dissolved is not particularly limited, but a solvent having a relatively high dielectric constant is preferably used. Specifically, ethylene carbonate, cyclic carbonates such as propylene carbonate, dimethyl carbonate, diethyl carbonate, acyclic carbonates such as ethyl methyl carbonate, tetrahydrofuran, 2-methyltetrahydrofuran, glymes such as dimethoxyethane, γ-butyrolactone and the like Examples thereof include lactones, sulfur compounds such as sulfolane, and nitriles such as acetonitrile. One or two of these
Mixtures of more than one species can be used.

Among these, in particular, one or more solvents selected from cyclic carbonates such as ethylene carbonate and propylene carbonate, and non-cyclic carbonates such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate are preferred. is there. In addition, those in which a part of hydrogen atoms in these molecules are substituted with halogen or the like can also be used. Further, additives and the like may be added to these solvents. As additives, for example, trifluoropropylene carbonate, vinylene carbonate,
1,6-Dioxaspiro [4,4] nonane
-2,7-done, 12-crown-4-ether and the like can be used for the purpose of enhancing the stability, performance and life of the battery.

The gel electrolyte that can be used as the electrolyte is
Usually, the above electrolyte is held by a polymer. In other words, the gel electrolyte is one in which the electrolyte is usually held in a polymer network and the fluidity as a whole is significantly reduced. Such a gel electrolyte exhibits properties such as ionic conductivity that are close to those of a normal electrolyte solution, but fluidity, volatility and the like are significantly suppressed, and safety is enhanced. The ratio of the polymer in the gel electrolyte is preferably 1 to
50% by weight. If the temperature is too low, the electrolyte cannot be held, and a liquid leak may occur. If it is too high, the ionic conductivity tends to decrease and battery characteristics tend to deteriorate.

As the polymer used for the gel electrolyte,
There is no particular limitation as long as it is a polymer that can form a gel together with the electrolytic solution, and polyester, polyamide, polycarbonate, those produced by polycondensation such as polyimide,
Polyurethane, polyurea, etc. produced by polyaddition, acrylic derivative polymers such as polymethyl methacrylate, and polyadditions produced by polyvinyl polymerization such as polyvinyl acetate, polyvinyl chloride, polyvinylidene fluoride, etc. and so on. Preferred polymers include polyacrylonitrile and polyvinylidene fluoride. Here, the polyvinylidene fluoride includes not only a homopolymer of vinylidene fluoride but also a copolymer with another monomer component such as hexafluoropropylene. Also, acrylic acid, methyl acrylate,
Ethyl acrylate, ethoxyethyl acrylate, methoxyethyl acrylate, ethoxyethoxyethyl acrylate, polyethylene glycol monoacrylate,
Ethoxyethyl methacrylate, methoxyethyl methacrylate, ethoxyethoxyethyl methacrylate, polyethylene glycol monomethacrylate, N, N-diethylaminoethyl acrylate, N, N-dimethylaminoethyl acrylate, glycidyl acrylate, allyl acrylate, acrylonitrile, N-vinylpyrrolidone, diethylene glycol di Acrylic derivative obtained by polymerizing monomers such as acrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and polyethylene glycol dimethacrylate. system Rimmer can also be preferably used.

The weight average molecular weight of the above polymer is usually 10
000 to 5,000,000. If the molecular weight is low, it is difficult to form a gel. If the molecular weight is high, the viscosity becomes too high and handling becomes difficult. The concentration of the polymer in the electrolytic solution may be appropriately selected according to the molecular weight, but is preferably from 0.1% by weight to 30% by weight. If the concentration is too low, it is difficult to form a gel, the retention of the electrolytic solution is reduced, and problems of flow and liquid leakage may occur. If the concentration is too high, the viscosity becomes too high, which causes difficulties in the process, and the proportion of the electrolytic solution is reduced, the ionic conductivity is reduced, and the battery characteristics such as rate characteristics may be reduced.

A completely solid electrolyte may be used as the electrolyte. As such a solid electrolyte, various solid electrolytes known so far can be used. For example, it can be formed by mixing the polymer used in the gel electrolyte and the supporting electrolyte salt at an appropriate ratio. In this case, in order to increase the conductivity, it is preferable to use a polymer having a high polarity and to have a skeleton having many side chains.

[0073]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist.

Example 1 Synthesis of an active material was performed according to the following formulation.

Material synthesis: First, 200 ml of distilled water was added to 4
Put in a 00ml beaker and mix the beaker with
Placed on a hot plate. The stir bar was then placed at the bottom of the beaker. Elvanol
50-42 powder (polyvinyl alcohol (PVA); EI DuPont de
Nemours, Inc., Wilmington, Del., 19801) (10.61 g) was slowly charged into a beaker and stirring was started at room temperature. Stirring is P
Continued until the VA was completely dissolved in distilled water.

In a second 400 ml beaker, add 15 ml of distilled water.
0 ml, Ni (O ₂ CCH ₃ ) ₂ -4H ₂ O (nickel acetate tetrahydrate, Strem Chem
medicals Inc. ), Newburyport,
Mass. 01950) 49.9923 g, G
a (NO ₃ ) ₃ (gallium nitrate, manufactured by Strem Chemicals) 0.2556 g, and LiO ₂ CCH ₃ -2H ₂ O
(Lithium acetate dihydrate, Aldrich Chemical (A
ldrich Chemical Co. ), Milwaukee, Wisconsin 53201) 21.5304
g. After the stir bar was placed in a second 400 ml beaker, it was placed on a conventional electromagnetic stir / hot plate. Stirring was started at room temperature to dissolve the salt in distilled water.

Next, the entire amount of the salt solution in the second 400 ml beaker was transferred to the first 400 ml beaker containing the PVA solution. While stirring, the salt / PVA mixed solution was heated to about 70-90 ° C. in about 4-6 hours.
The solution was cooled to room temperature over 48 hours with further stirring.

Next, the salt / PVA mixed solution was transferred to a 1-liter eggplant-shaped flask, and a Buchi-type rotary evaporator (PGC Scientific (P.
The flask was placed on a GC Scientific (Gaithersberg, MD 20898). The water in the flask was distilled off under reduced pressure while maintaining the water bath at about 40 ° C., to obtain a viscous salt / PVA solution. Next, the obtained viscous solution was transferred to a crystallization dish, the crystallization dish was put in a vacuum oven, and dehydration was further performed.

Next, the dried salt / PVA gel was pulverized, and the obtained pulverized gel was placed on an alumina tray. The gel is
First, heating (carbonization) was performed in an air vent furnace according to the heating schedule shown in Table 1 below.

[0080]

[Table 1]

Next, the sample was heated in an oxygen-rich atmosphere. The sample tray was placed in a quartz lined tube furnace, and the sample was pyrolyzed under the conditions shown in Table 2 below.

[0082]

[Table 2]

After completion of the pyrolysis, the product was transferred to a clean glass jar and stored in a dry air atmosphere. In the above embodiment, the two-step process, that is, the step of heating the gel and the step of heating after transferring the carbide to another heating vessel, has been described. However, it is apparent that these heating steps are combined. It can be done at the same time.

Material characterization: After synthesis, the properties of the material obtained were determined by X-ray diffraction (XRD) analysis and elemental analysis. The results are shown in Table 3 below.

[0085]

[Table 3]

Further, as a result of elemental analysis, it was confirmed that gallium was present in the sample. Also, the XRD data confirmed that a substantially single crystal phase identical to the lithium nickelate crystal structure was present in the sample.
Therefore, it can be seen that gallium exists as a doping element uniformly distributed in the octahedral 3 (a) position (nickel ion plane) of the sample, and does not exist as an isolated lithium gallate.

Next, an electrode was formed using the active material prepared above. First, a LiNi _0.995 Ga _0.005 O prepared above was placed in a clean dry 6-fluid ounce jar.
₂ 5.0 g, acetylene black (C-100, manufactured by Chevron Oil Co.),
0.588 g of Richmond, CA and 0.294 g of polyvinylidene fluoride powder (534,00 MW, manufactured by Aldrich Chemical Co.) were charged. Ceramic abrasive balls were added to the jar until about half of the jar was filled. Then, hexane was injected to soak the ceramic polishing ball. The jar is sealed with a cap lined with polytetrafluoroethylene (PFTE) and placed on a conventional ball mill roller for approximately 4
Milled for 8 hours. After grinding, hexane and the prepared material were separated from the polishing medium. Then, hexane was evaporated to obtain a residual dry fine black powder.

The obtained powder was analyzed using a laser scattering particle size distribution analyzer. The size of most particles is
1 to 100 μm, most of which are about 1 to 5 μm.
It was found to be in the range of 0 μm.

Next, to 1.0 g of the obtained powder, 1.0 ml of anhydrous dimethylformamide was added to form a paste, and the obtained paste was coated on an aluminum foil undercoated with a 0.003 inch gap coating knife. Coated. The coating is placed in an air atmosphere at about 50 ° C.
For about 12 hours. From the resulting coated foil, 9
The test electrode was punched out using a mm die. Then, using this test electrode and lithium metal (manufactured by FMC Corp.) as a counter electrode, Li dissolved in propylene carbonate (manufactured by Mitsubishi Chemical Corporation) was used.
The use of a 1 molar solution of AsF ₆ as a non-aqueous electrolyte, a coin-shaped battery (CR3032, Hosen Co., Osaka, Japan) was assembled.

The electrochemical characteristics of the assembled batteries were evaluated. The above assembled battery was installed on a standard battery cycle tester (Arbin BT-2043, manufactured by Arbin Instruments, College Station, TX), and a prospective theoretical battery for a battery test electrode was installed. Cycle tests were performed according to various discharge / charge rates calculated from the capacity.

Comparative Example 1: Commercially available LiNiO ₂ (Lectro Plus 200 cathode material, manufactured by FMC Corporation)
A battery was produced using Gastonia, NC, 28054), and the same electrochemical properties as in Example 1 were evaluated.

FIGS. 2 and 3 show two-dimensional plots showing the normalized battery voltage as a function of time for the batteries of Example 1 and Comparative Example 1, respectively. As is clear from the figure, the battery of the present invention shows a longer discharge time as compared with the conventional battery, indicating that the battery discharge time characteristics are improved.

FIGS. 4 and 5 are two-dimensional plots showing the battery capacity as a function of time for the batteries of Example 1 and Comparative Example 1, respectively. As is clear from the figure,
It can be seen that the battery of the present invention is superior to the conventional battery in capacity retention at several different charge / discharge rates.

FIGS. 6 and 7 show two-dimensional plots showing the Coulomb efficiency as a function of the number of cycles for the batteries of Example 1 and Comparative Example 1, respectively. As is clear from the figure, the battery of the present invention has first to
It can be seen that the coulombic efficiency of the battery during four cycles is excellent. Table 4 below summarizes the measurement results of the number of cycles and the Coulomb efficiency.

[0095]

[Table 4]

The above description and drawings are merely illustrative of the present invention, and various modifications and changes can be made in the present invention without departing from the gist thereof.

[0097]

The battery using the electrode active material in which the dopant of the present invention is uniformly contained has a battery capacity retention,
The battery discharge time and battery coulomb efficiency are excellent, and the industrial value of the present invention is high.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one embodiment of a battery manufactured according to the present invention.

FIG. 2 is a two-dimensional plot showing battery voltage as a function of standardized time for batteries manufactured according to the present invention.

FIG. 3 is a two-dimensional plot showing battery voltage as a function of standardized time for a conventional battery.

FIG. 4 is a two-dimensional plot showing battery capacity as a function of time for batteries made in accordance with the present invention.

FIG. 5 is a two-dimensional plot showing battery capacity as a function of time for a conventional battery.

FIG. 6 is a two-dimensional plot showing Coulombic efficiency as a function of cycle number for a battery made in accordance with the present invention.

FIG. 7 is a two-dimensional plot showing Coulombic efficiency as a function of cycle number for a conventional battery.

[Explanation of symbols]

 10: Battery 12: First electrode 14: Second electrode 16: Electrolyte 17: Active material layer 18: Active material component 20: Current collector

Claims (18)

[Claims] 1. A battery electrode comprising a current collector substrate, an electrode active material having a crystal structure, and a dopant substantially uniformly contained in the crystal structure of the electrode active material. 2. The electrode according to claim 1, wherein the dopant is selected from the group consisting of alkali metals, rare earth metals, gallium, and mixtures thereof. 3. The electrode according to claim 2, wherein the dopant is gallium. 4. The electrode according to claim 1, wherein the electrode active material is selected from the group consisting of a transition metal oxide, a lithium transition metal oxide, and a mixture thereof. 5. The method according to claim 1, wherein the lithium transition metal oxide is LiCoO.
_{2, LiNiO 2, LiMn 2 O} 4 and electrode according to claim 4 which is selected from the group consisting of mixtures. 6. The electrode according to claim 1, wherein the particle size of the electrode active material is 50 μm or less. 7. The electrode according to claim 1, wherein the particle size of the electrode active material is in a range of 1 to 10 μm. 8. A battery comprising an electrolyte, a first electrode and a second electrode, wherein at least one of the first electrode and the second electrode is the electrode according to any one of claims 1 to 7. 9. A method for manufacturing a battery, comprising: forming a first electrode; forming a second electrode; and associating at least one electrolyte with the first electrode and the second electrode. The first electrode forming step is a step of forming a current collector substrate; a step of preparing an electrode active material layer having a crystal structure containing a dopant uniformly; and forming the doped electrode active material on a current collector substrate. Applying a layer. 10. The step of preparing a doped electrode active material layer comprises dissolving an alkali metal acetate, a rare earth metal salt or a gallium metal acetate, and a polymer component in a substantially polar solvent to produce a gelatinous substance. Mixing the gelatinous substance; removing the substantially polar solvent from the resulting solution to obtain a substantially dry substance; pyrolyzing the dry substance; Grinding the material uniformly. 11. A step of: (1) dissolving a transition metal salt and at least one compound selected from a rare earth metal salt and a gallium salt in a solvent; and (2) converting a transition metal salt from the obtained solution. A step of obtaining a uniform product containing an element and at least one element selected from rare earth metals and gallium; and (3) a step of heat-treating the obtained uniform product. Electrode active material. (1) a step of dissolving a transition metal salt and at least one compound selected from a rare earth metal salt and a gallium salt together with a polymer component in a solvent to produce a gelatinous substance; 2) A battery electrode active material obtained through a step of removing the solvent from the obtained gelatinous substance to obtain a dry substance; and (3) a step of heat-treating the obtained dry substance. 13. A step of dissolving a transition metal salt and at least one compound selected from a rare earth metal salt and a gallium salt in a solvent; and (2) converting a transition metal salt from the obtained solution. A step of obtaining a uniform product containing an element and at least one element selected from rare earth metals and gallium; and (3) a step of heat-treating the obtained uniform product. Manufacturing method. 14. (1) a step of dissolving a transition metal salt and at least one compound selected from a rare earth metal salt and a gallium salt together with a polymer component in a solvent to form a gelatinous substance; 2) A method for producing an electrode active material, comprising: a step of removing the solvent from the obtained gelatinous substance to obtain a dry substance; and (3) a step of heat-treating the obtained dry substance. 15. The method for producing an electrode active material according to claim 13, wherein in the step (1), the solution further contains an alkali metal salt. 16. A step of dissolving a lithium salt, a nickel salt, and a gallium salt together with a polymer component in a solvent to produce a gelatinous substance; and (2) removing the solvent from the obtained gelatinous substance. Drying to obtain a dry substance;
(3) A method for producing an electrode active material, comprising a step of heat-treating the obtained dried substance. 17. The method for producing an electrode active material according to claim 16, wherein the electrode active material has an α-NaFeO ₂ type structure. 18. The method for producing a battery electrode according to claim 13, further comprising a step of pulverizing the product after the heat treatment.