JPH1079244A - Electrode and nonaqueous electrolyte second battery using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent paste from gelling by adding neutralized salt of organic acid and/ or inorganic acid to paste containing active materials and binder. SOLUTION: When LiNiO2 is used as an active material and polyvinylidene fluoride is used as binder, paste can easily gel. Paste can be prevented from gelling and good paste can be provided by adding inorganic acid or organic acid when active materials, binder and conductive materials are mixed in solvent. Organic acid having a functional group having strong electron attracting performance, and having relative high acidity is preferable since salt formed by neutralization does not deteriorate performance of the active material. Specifically, trifluoromethane sulfuric acid as strong acid of pH3 or less can be mentioned. Inorganic acid having relative high acidity is preferable for the same reason as the organic acid, and specifically phosphoric acid as strong acid of pH3 or less is selected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrode and a nonaqueous electrolyte secondary battery using the same.

[0002]

2. Description of the Related Art In recent years, non-aqueous batteries using an alloy or a carbon material capable of occluding and releasing lithium metal or lithium ions as a negative electrode material and a lithium-transition metal composite oxide as a positive electrode material have a high energy density. It is attracting attention as a battery.

A lithium ion secondary battery using LiCoO ₂ as the lithium-transition metal composite oxide has been put to practical use, but has a higher discharge capacity and a lower raw material cost.
LiNiO ₂ has attracted attention from the viewpoint of stable supply. However, when producing a positive electrode using LiNiO ₂ as the positive electrode active material, gelation of a paste which is a mixture of the binder and the conductive material has been a problem.
Gelation of a paste refers to a state in which fluidity and uniformity are lost due to an increase in viscosity. When gelation proceeds extremely, application to a current collector becomes impossible. Even if the gelation is slight, it greatly affects the resistance value of the prepared electrode sheet, etc., and lowers the battery characteristics such as the discharge capacity, current density dependency and low temperature characteristics. Has been a serious problem to be solved in electrode fabrication.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made based on such findings, and it is an object of the present invention to provide an excellent electrode paste even when an active material which easily causes gelation is used. It is to provide a manufacturing method thereof.

[0005]

SUMMARY OF THE INVENTION The present invention has the following arrangement to solve the above-mentioned problems.

"(1) An electrode comprising at least an electrode active material and a binder, and further comprising a neutralized salt of an organic acid and / or an inorganic acid.

(2) A non-aqueous electrolyte secondary battery using the electrode described in (1). "

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS For example, LiNiO is used as an active material.
_{When 2} is used and polyvinylidene fluoride is used as a binder, this paste is easily gelled. Furthermore, LiN
It has also been confirmed that when iO ₂ is suspended in water, it shows considerable basicity, and this fact indicates that paste gelation,
That is, it is presumed that polyvinylidene fluoride is denatured. That is, in a fluorine-based binder such as polyvinylidene fluoride, the acidity of a proton adjacent to a fluorine group is considerably higher due to the electron-withdrawing property of the fluorine group,
Therefore, the elimination of the proton proceeds easily under basic conditions. Anions are formed on the carbon after the elimination of protons, which promotes the elimination of fluorine groups, resulting in the formation of double bonds in the main chain of the binder molecule. It is presumed that such a reaction of the main chain proceeds on the surface of the highly basic active material, thereby modifying the macroscopic properties of the polymer such as binding property and solubility, resulting in gelation of the paste. .

The present inventors are not limited to LiNiO ₂ , but when a paste is prepared by combining a substance exhibiting basicity of pH 12 or more and a fluorine-based binder in a state of being suspended in an aqueous solution or water, generally It has been confirmed that gelation of the paste as described above occurs.

Accordingly, as a result of diligent research on a method of obtaining a good paste even when a relatively basic electrode active material is combined with a binder which is easily denatured under basic conditions, the present inventors have found that Have found that the above problem can be solved by adding an inorganic acid or an organic acid when mixing an active material, a binder and a conductive material in a solvent.
In the present invention, the organic acid is used without any particular limitation. Among them, a relatively high acidity organic acid having a strong electron-withdrawing functional group has a salt generated by neutralization as an electrode. This is preferable in that the performance of the active material is not reduced. Specifically, among phosphonic acids, sulfonic acids, carboxylic acids, and the like, strong acids having a pH of 3 or less are preferable in terms of high acidity, and at least one selected from trifluoromethanesulfonic acid, trifluoromethanephosphonic acid, and trifluoroacetic acid. It is particularly preferred to use one type.

The inorganic acid can be used without any limitation, but for the same reason as the organic acid, the inorganic acid having a relatively high acidity is such that the salt formed by the neutralization does not lower the performance of the electrode active material. It is preferable in terms of the point. Specifically, strong acids having a pH of 3 or less, such as phosphoric acid, sulfuric acid, and boric acid, are preferable in that they have high acidity.

The electrode of the present invention and the electrode active material used in a secondary battery using the same are not limited to the negative electrode and the positive electrode, but the present invention relates to the case where a highly basic electrode active material is used. This is particularly effective as a measure for preventing gelation of the electrode paste.

The negative electrode active material used in the present invention is not particularly limited, but a carbon body is often suitably used. The carbon body used in the present invention is not particularly limited, and generally used is one obtained by firing an organic substance, graphite, or the like. As the form of the carbon body, a powdered or fibrous carbon body is preferably used. As powdered carbon, natural graphite, artificial graphite,
Spherical coke such as Flude coke and Gilsonite coke, mesocarbon microbeads, polyacrylonitrile (PAN), polyvinyl alcohol, lignin, polyvinyl chloride, polyamide, polyimide, phenolic resin, furfuryl alcohol, and copolymers thereof Resin, fired pitch of coal or petroleum, fired cellulose, and the like. Examples of the fibrous carbon body include a PAN-based carbon fiber obtained from PAN or a copolymer thereof, a pitch-based carbon fiber obtained from a pitch such as coal or petroleum, a cellulosic carbon fiber obtained from cellulose, and a gas of a low molecular weight organic substance. And carbon fibers obtained by sintering the above-mentioned polyvinyl alcohol, lignin, polyvinyl chloride, polyamide, polyimide, phenol resin, furfuryl alcohol, and the like. .

Among them, a carbon body satisfying the characteristics is appropriately selected according to the characteristics of the electrode and the battery in which the carbon body is used. In the case where the carbon material is used for a negative electrode of a secondary battery using a non-aqueous electrolyte containing an alkali metal salt, a PAN-based carbon material, a pitch-based carbon material, and a vapor-grown carbon material are preferable. In particular, a PAN-based carbon body is preferably used in that the doping of an alkali metal ion, particularly, a lithium ion is good. The particle size of the powdered carbon body is
Preferably 0.1 to 100 μm is used, and more preferably 1 to 50 μm. The diameter of the carbon fiber should be determined so that each form can be easily adopted, but preferably 1 to 1000 μm is used, and more preferably 1 to 1000 μm.
It is 20 μm, particularly preferably 3 to 15 μm. It is also preferable to use several types of carbon fibers having different particle sizes. The average length of carbon fiber is 1m
m or less, more preferably 50 μm or less, and still more preferably 8 to 30 μm. Further, as a lower limit, a ratio of a fiber length to a fiber diameter (aspect ratio) is preferably 1 or more. If the thickness exceeds 1 mm, the coatability is poor when a slurry is formed to form a sheet-like electrode, and when the electrode is used, a short circuit between the positive and negative electrodes tends to occur. When the aspect ratio is less than 1, during powdering,
Since the active carbon surface is exposed by cleavage in the fiber direction, the cycle characteristics tend to be poor. The average length of the fiber is determined by measuring the length of at least 20 carbon bodies in the fiber direction by microscopic observation such as SEM. To cut or crush carbon fiber to 1mm or less,
Various mills can be used. In addition to the carbon body, for example, a compound such as a metal oxide or polyacene as shown in JP-A-7-235293 may be used as the negative electrode active material.

For the negative electrode of the battery according to the present invention, a metal such as copper or stainless steel can be used as a current collector to enhance the current collecting effect. The metal current collector is not particularly limited to a foil shape, a fiber shape, a mesh shape, and the like.For example, when a metal foil current collector is used, a sheet is formed by applying a slurry on the metal foil. A shaped electrode is produced. Carbon black such as acetylene black and Ketjen black is added to the sheet-like electrode as a conductive agent in order to further enhance the current collecting effect. Further, conductive powder such as carbon powder and metal powder may be added for the purpose of improving conductivity.

The positive electrode active material used in the present invention includes:
Materials generally used as a positive electrode active material, such as artificial or natural graphite powder, inorganic compounds such as carbon fluoride and metal oxide, and organic polymer compounds, are suitably used. In this case, when an inorganic compound such as a metal oxide is used as the positive electrode, a charge / discharge reaction occurs using doping and undoping of the cation. In the case of an organic polymer compound, a charge / discharge reaction occurs by doping and undoping of an anion. As described above, various charge / discharge reaction modes are adopted depending on the substance, and these are appropriately selected according to the required positive electrode characteristics of the battery. Specifically, inorganic compounds such as transition metal oxides and transition metal chalcogens containing alkali metals, conjugated polymers such as polyacetylene, polyparaphenylene, polyphenylenevinylene, polyaniline, polypyrrole, and polythiophene, and crosslinked polymers having disulfide bonds And positive electrode active materials used in ordinary secondary batteries such as thionyl chloride. Among these, in the case of a secondary battery using a non-aqueous electrolyte containing a lithium salt, transition metal oxides and transition metals such as cobalt, manganese, nickel, molybdenum, vanadium, chromium, iron, copper, and titanium are used. Chalcogens are preferably used. In particular, Li _x CoO ₂ (0 <x ≦ 1.
0), Li _x NiO ₂ (0 <x ≦ 1.0), or a lithium composite oxide in which part of these metal elements is replaced with an alkaline earth metal element and / or a transition metal element;
_{i x MnO 2 (0 <x} ≦ 1.0), Li x Mn 2 O
₄ (0 <x ≦ 1.3) and the like are preferably used. As described above, the present invention is particularly effective for LiNiO ₂ -based positive electrode active materials.

In the positive electrode used in the present invention, a metal such as aluminum, nickel, stainless steel or titanium can be used as a current collector in order to enhance the current collecting effect, similarly to the negative electrode. As in the case of the negative electrode, carbon black such as acetylene black and Ketjen black is added as a conductive agent. Further, conductive powder such as carbon powder and metal powder may be added for the purpose of improving conductivity.

The method for producing the electrode of the present invention is not particularly limited. For example, 0.01 to 2 mol% of an organic acid and / or an inorganic acid based on the electrode active material is dissolved in an organic solvent, and the electrode active material is added thereto. An electrode paste is prepared by adding a substance, a binder, and a conductive material if necessary, and sufficiently stirring and mixing using a mixer such as a homomixer. At this time, in order to prevent moisture absorption, the stirring and mixing are desirably performed in a dry atmosphere.

Next, the electrode paste is applied on the above-mentioned current collector, dried, pressed and formed into a sheet. The organic solvent and the solid content concentration used for pasting are not particularly limited, but may be appropriately determined in consideration of the binder used, the coating method, the drying conditions, and the like. In addition, various additives such as a surfactant for improving applicability, an antifoaming agent, a dispersant, an ultraviolet absorber, and a stabilizer for improving storage stability can be added to the electrode paste. .

Here, the addition amount of various organic acids and / or inorganic acids varies depending on the type of active material or acid, but is preferably 0.01 to 2 mol%, more preferably
It is 0.01 to 0.5 mol%. Here, when the addition amount of the organic acid and / or the inorganic acid is less than 0.01 mol%, the effect of preventing gelation is not sufficient, and when it exceeds 1 mol%, the salt generated by neutralization is added to the active material. Since the absorption and release of ions are inhibited, sufficient electrode performance tends not to be obtained. If a large amount of the organic acid and / or the inorganic acid remains in the electrode, the electrode performance may be adversely affected. Therefore, it is desirable that the amount does not exceed the amount necessary to neutralize the basicity of the electrode active material. Further, when the valence of the salt formed by neutralization with the added organic acid and / or inorganic acid is the same, the salt formed with the added organic acid and / or inorganic acid is equimolar, If the salt formed by monovalent inorganic acid and / or the divalent salt is divalent, the number of moles of the generated salt is half that of the added organic acid and / or inorganic acid.

The material of the separator used in the present invention is not particularly limited, and those satisfying the following general characteristics of the separator are preferably used. That is, the general characteristics required for the separator, the positive and negative electrodes are separated so that they do not physically contact,
The membrane itself has electrical insulation properties, has good electrolyte and ion permeability while holding the electrolyte, has low electric resistance, is chemically stable to the electrolyte, and is also electrochemically stable It is easy to get wet with electrolyte solution, has good retention of electrolyte solution, can be thinned so that electrodes can be efficiently filled in the battery can, and is required at the time of battery assembly and use. And have mechanical strength. Specifically, as thermoplastic resins, polyolefins such as polypropylene (PP), polyethylene (PE), ethylene vinylene acetate (EVA), N-substituted maleimide resin, poly 4-methylpentene-1, and polytetrafluoroethylene (PTFE), polystyrene, polyvinyl carbazole, polyvinylidene fluoride (PVDF), copolymer of PVDF and propylene hexafluoride, halogen-containing systems such as polyvinyl chloride (PVC), lignin, cellulose such as carboxycellulose (CMC) Water-soluble polymers such as polyvinyl alcohol (PVA), amides such as polyimide and polyamide, imides, acrylics such as polyacrylonitrile (PAN), polyacrylates and copolymers thereof, polycaprolactam, polyethylene Esters such as terephthalate and polybutylene butylene terephthalate, as well as polysulfone, polyester sulfone, polycarbonate, polyarylate, modified polyphenylene oxide, polyetheretherketone, silicone resin, and polyacetal are used. In addition, a phenoxy resin, an epoxy resin, or the like is used as the thermosetting resin. Further, a mixture of a thermoplastic resin and a thermosetting resin, two or more kinds of thermoplastic resins, two or more kinds of thermosetting resins, and the like are also used. The thickness of the separator is preferably 200 μm or less, more preferably 50 μm or less, particularly preferably 25 μm or less in order to reduce the internal resistance of the battery. The electrolytic solution of the battery according to the present invention is used without any particular limitation, and examples thereof include an acid or alkali aqueous solution and a non-aqueous solvent. Among them, propylene carbonate (PC), ethylene carbonate (EC), and propylene carbonate (EC) are used as the electrolyte of a secondary battery composed of the non-aqueous electrolyte containing the alkali metal salt.
γ-butyrolactone (BL), N-methylpyrrolidone (NMP), acetonitrile (AN), N, N-dimethylformamide, dimethyl sulfoxide, tetrahydrofuran (THF), 1,3-dioxolan, methyl formate, sulfolane, oxazolidone, Thionyl chloride, 1,
2-Dimethoxyethane (DME), dimethyl carbonate (DMC), diethylene carbonate (DEC), dimethylimidazolidinone, and the like, a derivative thereof, and a mixture of two or more kinds are preferably used.

The electrolyte contained in the electrolyte may be an alkali metal, especially lithium halide, perchlorate, thiocyanate, borofluoride, phosphorus fluoride, arsenic fluoride, aluminum fluoride, trifluoromethyl. Sulfates and the like are preferably used. The electrode of the present invention is widely used as an electrode for a battery. One embodiment in the case of a battery is described below. First, a lead is attached to the electrode of the present invention,
The positive and negative electrodes are spirally wound through the separator,
After arranging insulating plates on both upper and lower end surfaces of the wound electrode body, it is inserted into a battery can, and the positive electrode lead is welded to the battery lid, and the negative electrode lead is welded to the battery can. Then, an electrolyte is injected into the battery can in a non-aqueous atmosphere, and the battery can is caulked through an insulating sealing gasket whose surface is coated with a sealing material, thereby maintaining the airtightness in the battery and allowing the cylindrical can to be sealed. Assemble the water electrolyte secondary battery.

The secondary battery according to the present invention can be used as a video camera, a personal computer, a word processor, a radio-cassette, a mobile phone, a handy terminal, a CD player, an MD player by utilizing the features of light weight, high capacity and high energy density. It can be widely used in portable small electronic devices such as electric shaving, liquid crystal televisions and toys, and portable small electronic devices such as electric vehicles.

[0024]

EXAMPLES Specific embodiments of the present invention will be described below with reference to examples, but the present invention is not limited thereto.

Example 1 Phosphoric acid corresponding to 0.05 mol% with respect to LiNiO ₂ as an electrode active material was dissolved in N-methylpyrrolidone, and LiNiO ₂ and acetylene black (“Denka Black”) as a conductive material were added thereto. Electrochemical Co., Ltd.) and polyvinylidene fluoride (PVDF: KF polymer # 1100, manufactured by Kureha Chemical Co., Ltd.) as a binder were added at a weight ratio of 91: 3:
The mixture was added at a ratio of 6 and sufficiently stirred and mixed with a homomixer in dry air to obtain a positive electrode paste.

This paste was applied on an aluminum foil having a thickness of 20 μm, dried at 90 ° C. in a drier, applied on the back side, dried to form electrodes on both sides, and then pressed to a thickness of 200 μm.
An electrode having a width of 10 μm and a length of 20 mm was prepared.

Next, the discharge capacity of the electrode thus manufactured was evaluated. The electrolyte was propylene carbonate and dimethyl carbonate (each having a volume ratio of 1: 1) containing 1M LiBF _4, and a lithium electrode foil was used as a counter electrode and a reference electrode. The current density per active material was 4.2 V (vs. Li ⁺ / L) at a constant current of 30 mA / g.
Charged up to i). After the charging, the battery was discharged to 3.0 V (vs. Li ⁺ / Li) at the same current density as the charging. The capacity of the electrode was converted to the capacity per 1 g of the active material.

Example 2 An electrode was prepared and evaluated in the same manner as in Example 1 except that sulfuric acid was used instead of phosphoric acid as the acid to be added.

Example 3 An electrode was prepared in the same manner as in Example 1 except that trifluoromethanephosphonic acid was used instead of phosphoric acid as the acid to be added and 0.1 mol% was added to LiNiO ₂ . evaluated.

Example 4 An electrode was prepared in the same manner as in Example 1 except that trifluoromethanesulfonic acid was used instead of phosphoric acid as an acid to be added, and 0.1 mol% was added to LiNiO ₂ . evaluated.

Example 5 An electrode was prepared and evaluated in the same manner as in Example 1 except that trifluoroacetic acid was used instead of phosphoric acid as the acid to be added, and 0.1 mol% was added to LiNiO ₂ .

Example 6 An electrode was prepared and evaluated in the same manner as in Example 1 except that boric acid was used instead of phosphoric acid as an acid to be added.

Example 7 An electrode was prepared and evaluated in the same manner as in Example 1 except that acetic acid was used instead of phosphoric acid as the acid to be added.

Comparative Example 1 The same operation as in Example 1 was carried out except that no acid was added, but gelled in about 10 minutes from the start of paste kneading.
Coating on the current collector was not possible.

Table 1 summarizes the evaluation results of the above Examples and Comparative Examples.

From the comparison between Examples 1 to 7 and Comparative Example 1, the positive electrode paste to which the acid was added had good coatability, and among them, the electrode to which trifluoromethanephosphonic acid or trifluoromethanesulfonic acid was added was excellent. It can be seen that it has better performance.

Example 8 In the same manner as in Example 3, LiNiO ₂ positive electrode paste was applied on one surface of an aluminum foil having a thickness of 16 μm to form an electrode having a width of 8 cm.
Length 60 cm, weight of cathode active material per unit area is 20
0 g / m ² , dried at 100 ° C. for 15 minutes, applied to the other side, dried at 100 ° C. for 30 minutes, and further dried at 180 ° C. for 15 minutes to form a sheet using LiNiO _2. An electrode was prepared. The sheet-shaped electrode was roller-pressed at a linear pressure of about 100 kg / cm and pressed on an aluminum current collector, and then slit into a width of 54 mm and a length of 465 mm to obtain a positive electrode having a total thickness of 190 μm.

As the negative electrode active material, short fibrous carbon fiber ("Treca" milled fiber: MLD-30, manufactured by Toray Industries, Inc.) was used.
5% by weight, 10% by weight of PVDF (described above), and 5% by weight of acetylene black (described above) are used.
And kneaded to obtain a paste for a negative electrode.

This paste was applied on one side of a copper foil having a thickness of 10 μm to a width of 8 cm and a length of 60 cm of an electrode portion.
After drying at 0 ° C. for 15 minutes, the other surface is slightly reduced in the basis weight (the amount of the active material per unit area) and applied.
For 30 minutes, and further dried at 200 ° C. for 15 minutes in a nitrogen stream to produce a sheet-like electrode using short fibrous carbon fibers. This sheet-shaped electrode was slit to a width of 65 mm, pressed with a roller at a linear pressure of about 100 kg / cm, and pressed to a copper foil current collector, and then slit to a width of 56 mm and a length of 500 mm to obtain a 200 μm thick negative electrode.

Next, a secondary battery was manufactured using the positive and negative electrodes by the following method. FIG. 1 is a schematic longitudinal sectional view of the nonaqueous electrolyte secondary battery of the present invention. The battery is obtained by winding the negative electrode 1 and the positive electrode 2 obtained as described above, and housing the battery in a battery can 5 with insulators 4 disposed above and below the negative electrode 1 and the positive electrode 2. A battery lid 7 is attached to the battery can 5 by caulking via a sealing gasket 6, and is electrically connected to the negative electrode 1 and the positive electrode 2 via the negative electrode lead 11 and the positive electrode lead 12, respectively, so that the battery can function as a battery. Is configured.

In the above battery, the positive electrode lead 12 is
It is attached by welding to the current cutoff valve 8, and electrical insulation from the battery lid 7 is achieved through the current cutoff valve 8.
The current cutoff valve 8 is configured to be pushed up and deformed as the internal pressure of the battery increases, and the positive electrode lead 12 is welded to the current cutoff valve 8 by the deformation of the current cutoff valve 8. It is designed to be cut leaving some parts.

Such a non-aqueous electrolyte secondary battery was manufactured as follows. A negative electrode lead 11 made of nickel and a positive electrode lead 12 made of aluminum were welded to the current collector portions of the negative electrode 1 and the positive electrode 2 in advance. The negative electrode 1 and the positive electrode 2 are spirally wound while being laminated with the separator 3 interposed therebetween.
mm spiral wound electrode was obtained.

After the insulating plates 4 are arranged on both upper and lower end surfaces of the spirally wound electrode thus manufactured, the battery can 5
The positive electrode lead 12 was welded to the battery lid, and the negative electrode lead 11 was welded to the battery can 5. An electrolytic solution was injected into the battery can 5 in a glove box in an argon atmosphere.

The battery lid 5 is fixed by caulking the battery can 5 through the insulating sealing gasket 6 coated on the surface with asphalt, and the airtightness is maintained in the battery.
A cylindrical non-aqueous electrolyte secondary battery having a size was assembled.

The battery was charged at a constant current / constant voltage for 3 hours under the conditions of a charge end voltage of 4.2 V and a charge current of 1 A, and then was discharged under a condition of a discharge end voltage of 3.0 V and a discharge current of 0.2 A. Discharge was performed to determine the initial capacity.

Example 9 A cylindrical nonaqueous electrolyte secondary battery was assembled in the same manner as in Example 8, except that acetic acid was added to the positive electrode instead of trifluoromethanephosphonic acid. The initial capacity of this battery was determined.

Table 1 summarizes the evaluation results of the above Examples and Comparative Examples.

[0048]

[Table 1] From the comparison between Examples 1 to 9 and Comparative Example 1, the positive electrode paste to which an organic acid or an inorganic acid was added had good coatability,
Among them, it can be seen that the electrode to which trifluoromethanephosphonic acid or trifluoromethanesulfonic acid is added has better performance.

[0049]

According to the present invention, it is possible to provide a stable electrode in which gelation is prevented and a secondary battery using the same.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of the secondary battery of the present invention.

[Description of Signs] 1 ... Negative electrode 2 ... Positive electrode 3 ... Separator 4 ... Insulating plate 5 ... Battery can 6 ... Sealing gasket 7 ... Battery cover 8 ... Current interruption Valve 9: negative electrode current collector 10: positive electrode current collector 11: negative electrode lead 12: positive electrode lead

Claims (11)

[Claims] An electrode comprising at least an electrode active material and a binder and a neutralized salt of an organic acid and / or an inorganic acid. 2. The electrode according to claim 1, wherein said organic acid and / or inorganic acid accounts for 0.01 mol% or more and 2 mol% or less based on said electrode active material. 3. The organic acid and / or inorganic acid having a pH of 3
The electrode according to claim 1 or 2, wherein: 4. The electrode according to claim 1, wherein said organic acid is at least one selected from trifluoromethanesulfonic acid, trifluoromethanephosphonic acid and trifluoroacetic acid. . 5. The electrode according to claim 1, wherein said inorganic acid is at least one selected from phosphoric acid, sulfuric acid and boric acid. 6. The electrode according to claim 1, wherein said binder is a resin having a fluorine functional group in a molecule. 7. The electrode according to claim 1, wherein said electrode active material is a lithium / transition metal composite oxide. 8. The lithium / transition metal composite oxide is Li
_x CoO ₂ (0 <x ≦ 1.0), Li _x NiO ₂ (0 <
x ≦ 1.0), Li _x Co _y Ni _1−y O ₂ (0 <x ≦
1.0, 0 <y ≦ 1.0), and a compound obtained by adding one or more alkaline earth metal elements thereto, and Li
The electrode according to claim 1, wherein the electrode is selected from _x Mn ₂ O ₄ (0 <x ≦ 1.0). 9. A non-aqueous electrolyte secondary battery using the electrode according to claim 1. 10. The non-aqueous electrolyte secondary battery according to claim 9, wherein said non-aqueous electrolyte contains an electrolyte which is an alkali metal salt. 11. The non-aqueous electrolyte secondary battery according to claim 10, wherein said alkali metal salt is a lithium salt.