JP2020180037A - Inorganic solid oxide - Google Patents

Abstract

To provide a new inorganic solid oxide and the like.SOLUTION: An inorganic solid oxide is coated with a carbonaceous material.SELECTED DRAWING: None

Description

The present invention relates to novel inorganic solid oxides and the like.

Inorganic solid oxides such as barium titanate (BaTIO ₃ ) have properties such as ferroelectricity, and techniques for incorporating such inorganic solid oxides into electrodes are becoming known.

For example, in Patent Document 1, in a battery electrode in which an electrode mixture layer containing an active material is formed on a current collector, the electrode mixture layer contains an inorganic compound having a relative permittivity of 12 or more. An electrode characterized by the above is disclosed.

Japanese Unexamined Patent Publication No. 2001-283861

An object of the present invention is to provide a novel inorganic solid oxide or the like.

As described above, a technique for incorporating an inorganic solid oxide into an electrode is known. In addition, such an inorganic solid oxide is usually non-conductive.

When an inorganic solid oxide exhibiting such ferroelectric performance is added to the electrode mixture, the discharge capacity is increased (improved), but the electron conductivity is low, so that there is a problem that the DC resistance increases as a side effect. Further, a technique of coating an active material with an inorganic solid oxide is known, but in the sintering method, the diffusion resistance of Li ions in the active material particles coated with the inorganic solid oxide increases, and as a result, the diffusion resistance of Li ions increases. , There is a problem that the discharge capacity decreases.

Under these circumstances, the present inventor has found that a new material can be obtained by coating an inorganic solid oxide with a carbonaceous material from a completely different viewpoint from the conventional use (utilization method) of the inorganic solid oxide. I found it. Surprisingly, such a material can efficiently improve or improve the discharge capacity by using it as a component of an electrode (particularly a positive electrode), and in particular, can exhibit conductivity and is conductive. The present invention has been completed through further studies, finding that both conductivity and improvement or improvement of discharge capacity can be achieved without impairing the above, and as a result, an increase in DC resistance can be suppressed (improved).

That is, the present invention relates to the following inventions and the like.
[1] Inorganic solid oxide coated with carbonaceous material (material obtained by coating (coating) the inorganic solid oxide with carbonaceous material).
[2] The inorganic solid oxide (or material) according to [1], which is a sintered body (fired product) of an inorganic solid oxide and a carbonaceous material (carbonaceous raw material, carbonaceous precursor).
[3] The inorganic solid oxide (or material) according to [1] or [2], which is conductive.
[4] The inorganic solid oxide (or material) according to any one of [1] to [3], wherein the inorganic solid oxide is a ferroelectric substance.
[5] The inorganic solid oxide (or) according to any one of [1] to [4], wherein the inorganic solid oxide is an oxide containing at least one metal selected from titanium and niobium. material).
[6] The inorganic solid oxide (or material) according to any one of [1] to [5], wherein the inorganic solid oxide is a perovskite-type oxide.
[7] The inorganic solid oxide according to any one of [1] to [6], wherein the inorganic solid oxide contains at least one selected from an alkaline earth metal titanate and an alkali metal niobate. Or material).
[8] The inorganic solid oxide (or material) according to any one of [1] to [7], wherein the carbonaceous material contains amorphous carbon and / or graphite.
[9] The method for producing an inorganic solid oxide (or material) according to any one of [1] to [8] by coating the inorganic solid oxide with carbonaceous material.
[10] The production method according to [9], wherein a mixture (composition containing an inorganic solid oxide and a carbonaceous material) of an inorganic solid oxide and a carbonaceous material is fired (sintered).
[11] A positive electrode mixture containing the inorganic solid oxide according to any one of [1] to [8] (as a first conductive auxiliary agent and a first conductive material).
[12] A positive electrode active material layer (or a positive electrode having a positive electrode active material layer) containing the inorganic solid oxide (or material) according to any one of [1] to [8].
[13] The proportion of the inorganic solid oxide (or material) according to any one of [1] to [8] is 0.05 to 10% by mass with respect to the entire positive electrode active material layer, [12]. ] The positive electrode active material layer (or positive electrode).
[14] The ratio of the inorganic solid oxide (or material) according to any one of [1] to [8] is 0.1 part by mass or more with respect to 100 parts by mass of the positive electrode active material. 12] or [13]. The positive electrode active material layer (or positive electrode).
[15] Further, a conductive auxiliary agent (second conductive auxiliary agent, second conductive material) is contained, and 100 parts by mass of the conductive auxiliary agent (second conductive auxiliary agent) of [1] to [8]. Any one of [12] to [14], wherein the proportion of the inorganic solid oxide (first conductive auxiliary agent, first conductive material) according to any one is 0.1 to 95 parts by mass. The positive electrode active material layer (or positive electrode) according to one.
[16] The positive electrode active material layer according to any one of [12] to [15], wherein the coating mass of the positive electrode active material layer (for example, the coating mass of the positive electrode mixture) is 10 mg / cm ² or more. Or positive electrode).
[17] The positive electrode active material layer (or positive electrode) according to any one of [12] to [16], which contains a positive electrode active material capable of storing and releasing lithium ions and is used in a lithium ion secondary battery. ).
[18] A battery comprising the positive electrode active material layer (or positive electrode) according to any one of [12] to [17].
[19] The battery according to [18], which is a lithium ion secondary battery further provided with an electrolytic solution containing a lithium salt.
[20] The battery according to [19], wherein the lithium salt contains at least one selected from LiPF ₆ and lithium bis (fluorosulfonyl) imide.

According to the present invention, a novel inorganic solid oxide or the like can be provided. Such an inorganic solid oxide (material) is coated with a carbonaceous substance, and in particular, in one aspect of the present invention, such a carbonic substance-coated inorganic solid oxide is used to form an electrode (particularly a positive electrode). By constructing the composition, the discharge capacity [particularly, the discharge capacity at a relatively high amount of electricity or current (for example, 1C or more) in relation to the coating mass] is improved or improved as compared with the case where the inorganic solid oxide is not blended. Can be improved.

Further, in another aspect of the present invention, the inorganic solid oxide coated with the carbonaceous material as described above can obtain an inorganic solid oxide exhibiting conductivity, and the conductivity constituting the electrode (positive electrode or the like) can be obtained. It can be used as a material (conductive aid) or the like. By forming the electrode (particularly the positive electrode) in this way, the conductivity is not impaired even if it is replaced with a part or all of the conductive material or the conductive auxiliary agent, and in particular, the conductivity and the discharge capacity are improved. Alternatively, improvement can be efficiently compatible.

The relationship between the inorganic solid oxide (inorganic solid oxide coated with carbonaceous material) and the discharge capacity (furthermore, conductivity, compatibility between conductivity and discharge capacity) has not been known in the past. It is extremely surprising that such findings were obtained.

It is a Raman analysis result of the carbonaceous coated inorganic solid oxide obtained in Example 1. It is a Raman analysis result of the carbonaceous coated inorganic solid oxide obtained in Example 2. It is a Raman analysis result of the carbonaceous coated inorganic solid oxide obtained in Example 3.

[Carbonaceous coated inorganic solid oxide]
The inorganic solid oxide of the present invention is coated (coated, coated) with carbonaceous material. In other words, the material (new material) of the present invention can be said to be an inorganic solid oxide coated with carbonaceous material. Such a material may be a composite material (composite) of an inorganic solid oxide and a carbonaceous substance.

Such an inorganic solid oxide (hereinafter, may be referred to as a carbonaceous coated inorganic solid oxide or the like) is coated with carbonaceous material, and has conductivity in particular, although it depends on the form of coating and the like. It may be (may be a conductive material).

(Inorganic solid oxide)
The inorganic solid oxide is not particularly limited, but may be an insulator [dielectric, an insulator at room temperature (for example, 15 to 35 ° C.)], and may be a ferroelectric in particular.

The relative permittivity of the inorganic solid oxide may be, for example, 15 or more, preferably 20 or more, more preferably 100 or more, and particularly preferably 200 or more.

The upper limit of the relative permittivity of the inorganic solid oxide is not particularly limited, and examples thereof include 5000 and the like.

The relative permittivity may be a value at a predetermined temperature [for example, normal temperature (15 to 35 ° C.)].

The inorganic solid oxide may have a perovskite-type structure (may be a perovskite-type oxide). Such a perovskite-type oxide is an oxide represented by ABO ₃ (in the formula, A and B represent different elements).

The inorganic solid oxide is, for example, a typical element [for example, an alkaline earth metal or a Group 2 element of the Periodic Table (for example, magnesium), a Group 12 element of the Periodic Table (for example, zinc, cadmium, etc.), and the 13th Periodic Table. Group elements (eg, aluminum, gallium, indium, etc.), Periodic Table Group 15 elements (eg, Antimon, etc.)], Transition elements [eg, Periodic Table Group 3 elements (eg, Scandium, etc.), Periodic Table Group 4 Elements (eg, titanium, zirconium, hafnium, etc.), Periodic Table Group 5 elements (eg, vanadium, niobium, tantalum, etc.), Periodic Table Group 6 elements (eg, chromium, molybdenum, tungsten, etc.), Periodic Table No. 7. Group elements (eg, manganese, etc.), Periodic Table Group 9 elements (eg, cobalt, etc.), Periodic Table Group 10 elements (eg, nickel, etc.), Periodic Table Group 11 elements (eg, copper, etc.)], etc. It may be an oxide containing at least the element of.

Among these, the inorganic solid oxide may be an oxide containing at least one element (metal) selected from titanium and niobium.

In such an oxide, the element may be the element B of the perovskite type oxide.

In the perovskite type oxide, the element A is not particularly limited, but for example, a typical element [for example, an alkali metal or a Group 1 element of the periodic table (for example, lithium, sodium, potassium, etc.), an alkaline earth metal or a periodic table. Group 2 elements (eg magnesium, calcium, strontium, barium, etc.), Periodic Table Group 12 elements (eg, cadmium, etc.), Periodic Table Group 15 elements (eg, bismus, etc.)], Transitional elements [eg, periodic table It may be at least one element or the like selected from Table 3 elements (for example, lanthanoids and the like) and the like.

Among these, in particular, the inorganic solid oxide (perovskite type oxide) is an element A such as an alkali metal (for example, lithium, sodium, potassium, etc.), an alkaline earth metal (for example, calcium, barium, strontium, etc.) and the like. It may be an oxide having.

Specific examples of the inorganic solid oxide include alkali titanate earths such as titanium oxide [for example, calcium titanate (CaTIO ₃ ), strontium titanate (SrTiO ₃ ), barium titanate (BaTIO ₃ ) and the like. Metals, lead zirconate titanate (Pb (Zr, Ti) O ₃ ), etc.], zirconium oxide [eg, BaZrO _3, etc.], nioboxide [eg, lithium niobate (LiNbO ₃ ), sodium niobate (NaNbO) ₃ ), alkali metal niobate of potassium niobate (KNbO ₃ ), etc.], tantalum oxide (for example, LiTaO _3, etc.), tin oxide (for example, CaSnO ₃ , BaSnO _3, etc.) and the like. Inorganic solid oxides may be used alone or in combination of two or more.

Among these, titanium oxide (for example, alkaline earth metal titanate such as strontium titanate and barium titanate), niobium oxide (for example, alkali metal niobate such as lithium niobate) and the like are preferably used. May be good.

The shape of the inorganic solid oxide (or the inorganic solid oxide coated with carbonaceous material) is not particularly limited, but may be usually in the form of particles.

The average particle size of such particulate inorganic solid oxide (or inorganic solid oxide coated with carbonaceous material) is, for example, 0.001 to 30 μm, preferably 0.01 to 10 μm, and more preferably 0. It may be 1 to 1 μm.

For the average particle size, for example, a laser diffraction / scattering type particle size distribution meter (for example, Microtrac MT-3300EX2 manufactured by Nikkiso Co., Ltd.) is used to disperse the inorganic solid oxide as a predetermined dispersion medium (for example, 1% by mass NaCl). It may be a measured value (particle size, dispersion size) in the dispersion liquid dispersed in the aqueous solution).

The average particle size of the inorganic solid oxide (or the inorganic solid oxide coated with carbonaceous material) may be equal to or less than the thickness of the positive electrode active material layer described later, and is, for example, 1 times or less the thickness of the positive electrode active material layer. , 0.9 times or less, 0.8 times or less, 0.7 times or less, 0.6 times or less, 0.5 times or less, 0.4 times or less, and the like.

(Carbonaceous, carbonaceous coated inorganic solid oxide and its manufacturing method)
Inorganic solid oxides are coated with carbonaceous. According to such a carbonaceous-coated inorganic solid oxide, effects such as efficient charge / discharge capacity can be obtained. The reason for this is not clear, but for example, in the positive electrode active material layer, a concentration gradient of the positive electrode active material or its ions (for example, lithium ions) is usually generated, but it is considered that the charge / discharge capacity tends to decrease. However, by blending an inorganic solid oxide coated with a carbonaceous substance, the mobility of the positive electrode active material or its ions (for example, lithium ions) is increased, and such a concentration gradient is suppressed or relaxed (hence). It is considered that the charge / discharge capacity is improved by increasing the charge / discharge depth).

The form of the coating is not particularly limited, and may be a form in which carbonaceous material adheres (physically or chemically adheres) to the inorganic solid oxide, and in particular, the inorganic solid oxide and carbonaceous material (carbon). It may be coated in the form of a sintered body with a quality raw material or precursor).

In the form of such a coating, the inorganic solid oxide (for example, the surface of the inorganic solid oxide) and the carbonaceous material may be integrated (composited), for example, the amorphous carbonaceous material and / or graphite. It is a (graphite) -like carbonaceous material and easily coats inorganic solid oxides.

The carbon substance (carbon substance that coats the inorganic solid oxide) can be appropriately selected depending on the form of the coating, and for example, a conductive carbon material (for example, graphite, carbon black, carbon nanotube, carbon fiber, etc.) or the like can be used. It may be, in particular, amorphous carbon (amorphous carbon, amorphous carbon), graphite (or graphite-like or graphite layer, eg graphene). The inorganic solid oxide may be coated with one or more (different) carbonaceous substances.

By coating the carbonaceous material in a manner integrated with such an inorganic solid oxide, it is easy to obtain a conductive inorganic solid oxide (it is easy to develop or impart conductivity to the inorganic solid oxide). In addition, it is easy to improve or improve the discharge capacity while efficiently exhibiting conductivity.

It can be confirmed by a known method that the inorganic solid oxide and the carbonaceous material are integrated (for example, the formation of an amorphous carbon layer or a graphite layer) and that the carbonaceous material has conductivity. For example, the presence or formation of carbonaceous material (progress of carbonization) can be confirmed by Raman analysis or the like.

In a more specific embodiment, for example, a carbonaceous substance [for example, amorphous carbon (an inorganic solid oxide coated with a carbonaceous substance containing amorphous carbon)] is a specific band (Raman band) in Raman analysis (Raman spectrum). including [e.g., G-band ^(e.g., 1550 cm -1 1650 cm ^-1 such as a band including the 1580 cm ^-1 or near the), D-band ^(e.g., the 1350 cm ^-1 or near such 1300cm ^-1 ~1400cm -1 band), G 'band ^(e.g., in the range of ^{2650cm -1 ~2750cm -1), D +} D' band ^(e.g., in the range of 2800cm ^-1 ~3000cm -1), 2D 'band ^{(e.g., 3100cm} -1 ^{~3300cm At} least one band selected from (within the range of ^-1 ) (particularly at least G band and / or D band)] may be indicated.

Graphite (graphite itself) may show a band (single band) in the vicinity of 1580 cm ^-1 in Raman analysis (Raman spectrum), and carbonaceous substances containing graphite as a part (for example, amorphous carbon and graphite). In (carbonaceous chondrite containing), a band containing this 1580 cm- ¹ (for example, G band) may be shown.

The carbonaceous material may cover at least a part of the inorganic solid oxide (or integrate with at least a part of the inorganic solid oxide), and may cover the entire inorganic solid oxide (or its surface). It may be partially covered (or may have an uncovered portion).

The ratio of carbonaceous material is not particularly limited and may be a very small amount or a trace amount (for example, below the detection limit), but for example, 0.01 part by mass or more (for example) with respect to 100 parts by mass of the inorganic solid oxide. , 0.02 parts by mass or more), preferably 0.05 parts by mass or more (for example, 0.07 parts by mass or more), and more preferably 0.1 parts by mass or more (for example, 0.12 parts by mass or more). Also, 0.15 parts by mass or more, 0.2 parts by mass or more, 0.3 parts by mass or more, 0.5 parts by mass or more, 0.7 parts by mass or more, 0.8 parts by mass or more, 1 part by mass or more, etc. It may be.

The upper limit of the carbon content is not particularly limited, and for example, 1000 parts by mass, 800 parts by mass, 500 parts by mass, 300 parts by mass, 200 parts by mass, and 100 parts by mass with respect to 100 parts by mass of the inorganic solid oxide. It may be a mass part, 80 mass part, 50 mass part, 30 mass part, 20 mass part, 10 mass part, 5 mass part, 3 mass part and the like.

The proportion of carbonaceous material is not particularly limited and may be a very small amount or a very small amount (for example, below the detection limit), but the total amount of inorganic solid oxide and carbonaceous material (inorganic solid oxide coated with carbonaceous material). With respect to 0.01% by mass or more (for example, 0.02% by mass or more), preferably 0.05% by mass or more (for example, 0.07% by mass or more), and more preferably 0.1% by mass or more (for example, 0.1% by mass or more). For example, it may be about 0.12% by mass or more), 0.15% by mass or more, 0.2% by mass or more, 0.3% by mass or more, 0.5% by mass or more, 0.7% by mass or more. , 0.8% by mass or more, 1 part by mass or more, and the like.

The upper limit of the proportion of carbonaceous material is not particularly limited, and is, for example, 99.9% by mass or 99 with respect to the total amount of inorganic solid oxide and carbonaceous material (inorganic solid oxide coated with carbonaceous material). .5% by mass, 99% by mass, 95% by mass, 90% by mass, 80% by mass, 70% by mass, 60% by mass, 50% by mass, 40% by mass, 30% by mass, 20% by mass, 10% by mass, 8 It may be mass%, 5 mass%, 3 mass%, 2 mass% or less, 1.5 mass%, 1 mass%, 0.5 mass% and the like.

The thickness of the carbonaceous material (thickness of the coating layer formed of the carbonaceous material) is not particularly limited and may be a very thin thickness (for example, below the detection limit), but is, for example, 0.2 nm or more (for example, 0). It may be about 0.3 nm to 100 μm), preferably 0.5 nm or more (for example, 0.6 to 50 μm), and more preferably about 0.6 nm or more (for example, 0.7 nm to 30 μm).

The ratio and thickness of carbonaceous material may be measured and calculated by, for example, TGA (thermogravimetric analysis) or the like. For example, the carbonaceous ratio may be calculated and calculated by measuring the weight change (weight loss) by TGA analysis, and the carbonaceous thickness (average thickness) is the weight change and the inorganic solid oxide. It may be calculated / calculated based on the surface area [(average) surface area obtained from the (average) particle size] and the density of carbonaceous material.

The inorganic solid oxide (carbonic coated inorganic solid oxide) of the present invention can be produced by coating (coating, coating) the inorganic solid oxide.

The coating method can be selected according to the mode of coating the carbonaceous material. For example, a method of applying the carbonaceous material to the inorganic solid oxide [for example, a method of adhering (sprinkling) the carbonaceous material, a solvent composition containing the carbonaceous material). May be applied to an inorganic solid oxide (spray, etc.) or immersed (further, if necessary, dried), etc.], and in particular, a mixture of the inorganic solid oxide and a carbonaceous material [inorganic solid oxidation] A method may be used in which a composition containing a substance and a carbonaceous material and an inorganic solid oxide to which the carbonaceous material is attached (coated with the carbonaceous material) are fired (carbonized). By such a firing treatment, it is easy to efficiently integrate carbonaceous material into the inorganic solid oxide (composite, form a graphite layer).

The carbonaceous material is not particularly limited as long as it is a material capable of forming a carbonaceous substance (carbon-containing material), and is an organic material (organic compound), for example, a resin or a polymer {for example, a vinyl resin [for example, vinyl alcohol]. Lu-based resins (eg, polyvinyl alcohol, etc.), amide-based resins (eg, polyacrylamide, polyvinylpyrrolidone, etc.), amine-based resins (eg, polyethyleneimine, etc.), halogen-containing resins (eg, polyvinyl chloride, etc.)], Phenolic resins, furan resins, epoxy resins, cellulose-based resins [eg, cellulose, cellulose derivatives (eg, cellulose ethers, cellulose esters, etc.), etc.], pitch-based materials (eg, pitch, etc.)}, low molecular weight or non-polymeric types Ingredients {for example, aromatic compounds [for example, phenolic compounds (for example, phenol, fluoroglucolcinol, etc.)], tar, etc.} and the like can be mentioned. The carbonaceous material (carbonaceous precursor, carbonaceous precursor) may be used alone or in combination of two or more.

The carbonaceous material may be a material that carbonizes at a temperature equal to or lower than the decomposition point (decomposition temperature) of the inorganic solid oxide. In other words, the carbonization temperature of the carbonaceous material may be equal to or lower than the decomposition point of the inorganic solid oxide. The carbonization temperature can be measured by TG-DTA analysis (thermogravimetric differential thermal analysis) or the like regardless of the type (for example, low molecular weight compound, polymer, etc.). The decomposition point of the inorganic solid oxide can also be measured by TG-DTA analysis (thermogravimetric differential thermal analysis) or the like.

Further, the carbonaceous material may be soluble in a solvent from the viewpoint of efficiently coating with carbonaceous material.

A mixture of the inorganic solid oxide and the carbonaceous material can be obtained by mixing them, and the mixing method is not particularly limited. For example, the mixture may be obtained by mixing the inorganic solid oxide and the carbonaceous material in a solvent (in the presence of the solvent) and removing the solvent (adhering the carbonic material to the inorganic solid oxide). May be good).

The solvent can be appropriately selected depending on the type of carbonaceous material and the like, and is not particularly limited, and for example, a solvent (water, organic solvent, etc.) described later may be used. The solvent may be a solvent capable of dissolving the carbonaceous material, or may dissolve the carbonaceous material.

The mixture may be pre-calcined (carbonized, pre-carbonized) prior to calcination. Such pre-baking may be a step for removing impurities (for example, solvent, low molecular weight components, etc.) in the mixture. Further, the pre-calcination may be a step for adjusting the degree of carbonization of the carbonaceous material. In the pre-baking, the conditions may be adjusted as appropriate so that the removal described later can be performed efficiently.

In the pre-baking, the pre-baking temperature can be selected according to the type of carbonaceous material and the like, for example, 650 ° C or lower (for example, 150 to 600 ° C), preferably 550 ° C or lower (for example, 200 to 500 ° C), and further. It may be preferably 450 ° C. or lower (for example, 250 to 400 ° C.).

Pre-baking may usually be carried out in a non-oxidizing atmosphere (in nitrogen, helium, argon, etc.).

Pre-baking may be performed under stirring. Further, the preliminary firing may be performed under normal pressure or under reduced pressure.

The pre-baking time can be appropriately selected depending on the type of carbonaceous material and the like, and is not particularly limited, and may be, for example, 10 minutes or more, 20 minutes or more, 30 minutes or more.

After the pre-baking, the excess carbonaceous material (carbonaceous material that has not adhered to or coated with the inorganic solid oxide) may be removed, if necessary. The removal (separation) method is not particularly limited, and examples thereof include a method of washing the pre-baked product (mixture after pre-firing) with an appropriate solvent (solvent described later, etc.).

In the firing (carbonization) treatment, the firing temperature can be selected depending on the type of carbonaceous material and the like, and is, for example, 500 ° C. or higher (for example, 500 to 4000 ° C.), preferably 550 ° C. or higher (for example, 550 to 3000 ° C.). ), More preferably 600 ° C. or higher (for example, 600 to 2500 ° C.), 650 ° C. or higher (for example, 650 to 2000 ° C.), or the like. The upper limit of the firing temperature is not particularly limited and may be high from the viewpoint of carbonization (conductivity), but from the viewpoint of efficiently guaranteeing and realizing the function as an inorganic solid oxide. , It may be below the decomposition point (decomposition temperature) of the inorganic solid oxide (or heat resistant temperature).

Firing may usually be carried out in a non-oxidizing atmosphere (in nitrogen, helium, argon, etc.).

The firing may be carried out under stirring. Further, the firing may be performed under normal pressure or reduced pressure.

The firing time can be appropriately selected depending on the type of carbonaceous material and the like, and is not particularly limited, and may be, for example, 10 minutes or more, 30 minutes or more, 60 minutes or more, 120 minutes or more, and the like.

(Use of inorganic solid oxide coated with carbonaceous material, etc.)
The carbonaceous coated inorganic solid oxide can be used, for example, as a component of the electrode (component of the electrode). In particular, among the electrodes, the discharge capacity and the like can be improved or improved by using the constituent components of the positive electrode.

Further, the carbonaceous coated inorganic solid oxide having conductivity can be used as a conductive material. Therefore, such an inorganic solid oxide can be used as a conductive material constituting an electrode or the like.

[Positive electrode active material coated with carbonaceous coated inorganic solid oxide]
In another aspect of the invention, the positive electrode active material of the invention is coated (coated, coated) with a particulate carbonaceous coated inorganic solid oxide. In other words, the material of the present invention can be said to be a positive electrode active material coated with a carbonaceous coated inorganic solid oxide. Such a material may be a composite material (composite) of a carbonaceous coated inorganic solid oxide and a positive electrode active material.

The particulate carbonaceous coated inorganic solid oxide may cover at least a part of the positive electrode active material (or be integrated with at least a part of the inorganic solid oxide), and the positive electrode active material (or its surface) may be coated. ) May be completely covered, or a part may be covered (or may have an uncovered portion).

As the particulate carbonaceous coated inorganic solid oxide used for coating the positive electrode active material, the same as the above-mentioned inorganic solid oxide may be used, and niobium oxide (for example, lithium niobate or the like) may be used. (Alkalimetal niobate) and the like may be preferably used.

Here, the present inventor has found that the smaller the average particle size of the carbonaceous coated inorganic solid oxide, the greater the influence on the discharge capacity, that is, the discharge capacity can be further improved or improved.

The average particle size of the particulate carbonaceous coated inorganic solid oxide used for coating the positive electrode active material may be, for example, 5 μm or less, preferably 2 μm or less, and more preferably 1 μm or less. The lower limit is not particularly limited, and is, for example, 0.001 μm or more.

The average particle size of the positive electrode active material coated with the carbonaceous coated inorganic solid oxide may be equal to or less than the thickness of the positive electrode active material layer, for example, 1 times or less and 0.9 times the thickness of the positive electrode active material layer. Below, it may be 0.8 times or less, 0.7 times or less, 0.6 times or less, 0.5 times or less, 0.4 times or less, and the like.

The ratio and thickness of carbonaceous material may be the same ratio and thickness as described above.

The method of coating the positive electrode active material with the particulate carbonaceous coated inorganic solid oxide can be selected depending on the mode of coating the carbonaceous coated inorganic solid oxide. For example, a method of applying a particulate carbonaceous coated inorganic solid oxide to a positive electrode active material [for example, a method of adhering (spraying) a carbonaceous coated inorganic solid oxide, a solvent composition containing a carbonaceous coated inorganic solid oxide. Is applied to the positive electrode active material (spray, etc.) or immersed (further, if necessary, dried), etc.], and in particular, a mixture of the positive electrode active material and the carbonaceous coated inorganic solid oxide material [ A composition containing a positive electrode active material and a carbonaceous coated inorganic solid oxide material, and a positive electrode active material to which a carbonaceous coated inorganic solid oxide material is attached (coated with a carbonic coated inorganic solid oxide material)] are fired. It may be a method. By such a firing treatment, it is easy to efficiently integrate (composite) the inorganic solid oxide with the positive electrode active material.

A mixture of the positive electrode active material and the carbonaceous coated inorganic solid oxide can be obtained by mixing them, and the mixing method is not particularly limited. For example, the positive electrode active material and the carbonaceous coated inorganic solid oxide may be mixed in a solvent (in the presence of the solvent), and the mixture may be obtained by removing the solvent (carbonic coated inorganic solid on the positive electrode active material). Oxide material may be attached).

The solvent can be appropriately selected depending on the type of carbonaceous coated inorganic solid oxide material and the like, and is not particularly limited, and for example, a solvent (water, organic solvent, etc.) described later may be used. The solvent may be a solvent capable of dissolving the inorganic solid oxide material, or may dissolve the inorganic solid oxide material.

In the calcination treatment, the calcination temperature can be selected depending on the type of carbonaceous coated inorganic solid oxide material and the like, and is, for example, 500 ° C. or higher (for example, 500 to 4000 ° C.), preferably 550 ° C. or higher (for example, 550 to 550 ° C.). 3000 ° C.), more preferably 600 ° C. or higher (for example, 600 to 2500 ° C.), 650 ° C. or higher (for example, 650 to 2000 ° C.), or the like. The upper limit of the firing temperature is not particularly limited, and from the viewpoint of efficiently guaranteeing and realizing the function as the carbonaceous coated inorganic solid oxide, the decomposition point (decomposition temperature) of the carbonic coated inorganic solid oxide. It may be the following (or heat resistant temperature).

Firing may usually be carried out in a non-oxidizing atmosphere (in nitrogen, helium, argon, etc.).

The firing may be carried out under stirring. Further, the firing may be performed under normal pressure or reduced pressure.

The firing time can be appropriately selected depending on the type of carbonaceous material and the like, and is not particularly limited, and may be, for example, 10 minutes or more, 30 minutes or more, 60 minutes or more, 120 minutes or more, and the like.

As described above, in another aspect of the present invention, a positive electrode active material coated with a carbonaceous coated inorganic solid oxide having an average particle diameter of 5 μm or less (the positive electrode active material is coated with the carbonic coated inorganic solid oxide). (Coated material) may be used. Further, in the positive electrode active material (or material), the carbonaceous coated inorganic solid oxide may contain an alkali metal niobate.

Hereinafter, as a typical aspect, an aspect constituting the positive electrode will be described in detail.

[Positive electrode]
The positive electrode has a positive electrode active material layer. For such a positive electrode active material layer, for example, as will be described later, a positive electrode mixture (positive electrode mixture containing a positive electrode active material) is used [for example, coating (coating) of a positive electrode mixture (positive electrode active material composition). )] Can be formed.

The present invention is characterized in that the positive electrode active material layer (or the positive electrode mixture) contains a carbonaceous coated inorganic solid oxide.

(Positive electrode active material)
As the positive electrode active material, various ions (lithium ion, sodium ion, etc.) may be stored and released, and for example, it is used in a conventionally known secondary battery (lithium ion secondary battery, sodium ion secondary battery, etc.). A positive electrode active material or the like to be used can be used.

The lithium ion absorbing and releasing active material capable (e.g., the active material of the lithium ion secondary battery) The lithium cobaltate, lithium nickelate, lithium _manganate, Ya _{LiNi 1-x-y Co x} Mn y O 2 Transition metal oxides such as ternary oxides represented by LiNi _1-xy Co _x Al _y O ₂ (0 ≦ x ≦ 1, 0 ≦ y ≦ 1), LiAPO ₄ (A = Fe, Mn, Solid-soluble materials (electrochemically inactive layered Li ₂ MnO ₃ and electrochemically active layered LiMO ₂ (M =) incorporating a plurality of compounds having an olivine structure such as Ni and Co) and transition metals. Solid solution with transition metals such as Co and Ni)), LiCo _x Mn _1-x O ₂ (0 ≦ x ≦ 1), LiNi _x Mn _1-x O ₂ (0 ≦ x ≦ 1), Li ₂ APO ₄ F Compounds having an olivine fluoride structure such as (A = Fe, Mn, Ni, Co), sulfur and the like can be used. These may be used alone or in combination of two or more.

Examples of active materials capable of occluding and releasing sodium ions (for example, active materials of sodium ion secondary batteries) include NaNiO ₂ , NaCoO ₂ , NamnO ₂ , NaVO ₂ , NaFeO ₂ , and Na (Ni _X Mn _1-X ) O. ₂ (0 <X <1), Na (Fe _X Mn _1-X ) O ₂ (0 <X <1), NaVPO ₄ F, Na ₂ FePO ₄ F, Na ₃ V ₂ (PO ₄ ) _3, etc. Be done. These may be used alone or in combination of two or more.

The positive electrode active material may be used alone or in combination of two or more.

Among these, a positive electrode active material capable of occluding and releasing lithium ions may be preferably used. Such a positive electrode active material is used, for example, in a lithium ion secondary battery or the like using a non-aqueous electrolyte solution. Such a non-aqueous system usually has a lower ionic conductivity than an aqueous system, but in the present invention, even in such a case, improvement of the discharge capacity and the like can be efficiently realized.

(Other ingredients)
The positive electrode active material layer (positive electrode mixture) may contain other components (components other than the positive electrode active material and the carbonaceous coated inorganic solid oxide).

Examples of such other components include, but are not limited to, conductive aids (conductive substances, conductive materials), carbonaceous-coated inorganic solid oxides, binders, and the like.

Examples of the conductive auxiliary agent include carbon black (for example, acetyline black, etc.), graphite, carbon nanotubes (for example, single-walled carbon nanotubes, multi-walled carbon nanotubes, etc.), carbon fibers (for example, vapor-phase carbon fibers, etc.), and the like. Examples include metal powder materials. The conductive auxiliary agent may be used alone or in combination of two or more.

The carbonaceous coated inorganic solid oxide having conductivity can be used as a conductive auxiliary agent (conductive material) by itself. In such a case, the conductive auxiliary agent (conductive material) can be said to be a conductive auxiliary agent (conductive material) that is not a carbonaceous-coated inorganic solid oxide. In such a case, the carbonaceous coated inorganic solid oxide is the first conductive auxiliary agent (first conductive material), and the conductive auxiliary agent (the conductive auxiliary agent that is not the carbonic coated inorganic solid oxide) is the second. It can be called a conductive auxiliary agent (second conductive material).

Examples of the binder (binder) include fluororesins such as polyvinylidene fluoride and polytetrafluoroethylene; synthetic rubbers such as styrene-butadiene rubber and nitrile butadiene rubber; polyamide resins such as polyamideimide; polyethylene, polypropylene and the like. Polypropylene-based resin; poly (meth) acrylic-based resin; polyacrylic acid; cellulose-based resin such as carboxymethyl cellulose; and the like. The binder may be used alone or in combination of two or more.

(Positive electrode active material layer)
In the positive electrode active material layer, the ratio of the positive electrode active material (the ratio of the positive electrode active material to the total solid content in the positive electrode mixture) is, for example, about 50% by mass or more (for example, 60% by mass or more, 70% by mass or more). It may be selected from the range, and may be 75% by mass or more (for example, 80% by mass or more), preferably 85% by mass or more (for example, 88% by mass or more), and more preferably 90% by mass or more.

In the positive electrode active material layer, the upper limit of the ratio of the positive electrode active material is not particularly limited, but is, for example, 99.5% by mass, 99% by mass, 98.5% by mass, 98% by mass, 97.5% by mass. , 97% by mass, 96% by mass, 95% by mass, 94% by mass, 93% by mass, and the like.

An appropriate range (for example, 90 to 99% by mass) may be set by appropriately combining these lower limit values and upper limit values (others are the same).

In the positive electrode active material layer, the present form of the carbonaceous coated inorganic solid oxide is not particularly limited, and is contained in the positive electrode active material in the form of coating the positive electrode active material (such as a sintered body with the positive electrode active material) or in the positive electrode active material (dope). The positive electrode active material may be in any of a form in which the positive electrode is used, a form in which the positive electrode active material is separated from the positive electrode active material, a form in which these are mixed, and the like, and in particular, from the viewpoint of cost and efficiency in improving or increasing the discharge capacity. It may be in a form separated from.

In the positive electrode active material layer, the ratio of the carbonaceous coated inorganic solid oxide (or the carbonic coated inorganic solid oxide in the positive electrode active material coated with the carbonic coated inorganic solid oxide, the same applies hereinafter) is, for example, 0. It may be selected from the range of about 01% by mass or more (for example, 0.05% by mass or more), 0.1% by mass or more (for example, 0.2% by mass or more), preferably 0.3% by mass or more (for example, 0.3% by mass or more). For example, it may be 0.4% by mass or more), more preferably 0.5% by mass or more (for example, 0.7% by mass or more, 0.8% by mass or more, etc.).

The upper limit of the proportion of the carbonaceous coated inorganic solid oxide in the positive electrode active material layer is not particularly limited, but is, for example, 20% by mass, 19% by mass, 18% by mass, 17% by mass, 16% by mass, and 15%. Mass%, 14 mass%, 13 mass%, 12 mass%, 11 mass%, 10 mass%, 9 mass%, 8 mass%, 7 mass%, 6 mass%, 5 mass%, 4 mass%, 3 mass% , 2% by mass, 1.5% by mass, etc.

The ratio of the carbonaceous coated inorganic solid oxide may be selected from the range of, for example, about 0.01 part by mass or more (for example, 0.05 part by mass or more) with respect to 100 parts by mass of the positive electrode active material, and is 0. .1 parts by mass or more (for example, 0.2 parts by mass or more), preferably 0.3 parts by mass or more (for example, 0.4 parts by mass or more), more preferably 0.5 parts by mass or more (for example, 0.7 parts by mass). It may be (mass part or more, 0.8 parts by mass or more, 0.9 parts by mass or more, 1 part by mass or more, etc.).

The upper limit of the ratio of the carbonaceous coated inorganic solid oxide to 100 parts by mass of the positive electrode active material is not particularly limited, but is, for example, 20 parts by mass, 19 parts by mass, 18 parts by mass, 17 parts by mass, and 16 parts by mass. , 15 parts by mass, 14 parts by mass, 13 parts by mass, 12 parts by mass, 11 parts by mass, 10 parts by mass, 9 parts by mass, 8 parts by mass, 7 parts by mass, 6 parts by mass, 5 parts by mass, 4 parts by mass, 3 parts. It may be a mass part, 2 parts by mass, 1.5 parts by mass, or the like.

When the positive electrode active material layer contains a conductive auxiliary agent (a conductive auxiliary agent that is not a carbonaceous coated inorganic solid oxide), in the positive positive material active material layer, the conductive auxiliary agent (second conductive auxiliary agent, second conductive material) The ratio may be selected from the range of, for example, about 0.1% by mass or more (for example, 0.2% by mass or more), and is preferably 0.3% by mass or more (for example, 0.4% by mass or more). 0.5% by mass or more (for example, 0.8% by mass or more), more preferably 1% by mass or more (for example, 1.2% by mass or more, 1.5% by mass or more, 1.8% by mass or more, 2% by mass) % Or more, 2.2% by mass or more, 2.5% by mass or more, etc.).

When the positive electrode active material layer contains a conductive auxiliary agent (a conductive auxiliary agent that is not a carbonaceous coated inorganic solid oxide), the conductive auxiliary agent (second conductive auxiliary agent, second conductive material) is contained in the positive electrode active material layer. The upper limit of the ratio of) is not particularly limited, but is, for example, 30% by mass, 29% by mass, 28% by mass, 27% by mass, 26% by mass, 25% by mass, 24% by mass, 23% by mass, and 22% by mass. , 21% by mass, 20% by mass, 19% by mass, 18% by mass, 17% by mass, 16% by mass, 15% by mass, 14% by mass, 13% by mass, 12% by mass, 11% by mass, 10% by mass, 9 It may be mass%, 8 mass% or less, 7 mass%, 6 mass%, 5 mass%, 4 mass% and the like.

When the positive electrode active material layer contains a conductive auxiliary agent (second conductive auxiliary agent, second conductive material), the carbonaceous coated inorganic solid oxide (first conductive auxiliary agent, first conductive material) The ratio is, for example, from a range of about 0.01 parts by mass or more (for example, 0.02 parts by mass or more) with respect to 100 parts by mass of the conductive aid (second conductive auxiliary agent, second conductive material). It may be selected, and may be selected by 0.03 parts by mass or more (for example, 0.05 parts by mass or more), preferably 0.1 parts by mass or more (for example, 0.15 parts by mass or more), and more preferably 0.2 parts by mass. The above (for example, 0.25 parts by mass or more, 0.3 parts by mass or more, etc.) may be used, and 0.5 parts by mass or more, 1 part by mass or more, 3 parts by mass or more, 5 parts by mass or more, and 10 parts by mass or more. As mentioned above, it may be 15 parts by mass or more, 20 parts by mass or more, 25 parts by mass or more, 30 parts by mass or more, and the like.

When the positive electrode active material layer contains a conductive auxiliary agent (second conductive auxiliary agent, second conductive material), 100 parts by mass of the conductive auxiliary agent (second conductive auxiliary agent, second conductive material). The upper limit of the ratio of the carbonaceous coated inorganic solid oxide (first conductive auxiliary agent, first conductive material) to the carbonaceous coated inorganic solid oxide is not particularly limited, but is, for example, 2000 parts by mass, 1500 parts by mass, and 1200 parts by mass. 1000 parts by mass, 900 parts by mass, 800 parts by mass, 700 parts by mass, 600 parts by mass, 500 parts by mass, 400 parts by mass, 300 parts by mass, 200 parts by mass, 150 parts by mass, 100 parts by mass, 95 parts by mass, 90 parts by mass. Parts, 85 parts by mass, 80 parts by mass, 70 parts by mass, 60 parts by mass, 50 parts by mass, and the like may be used.

When the positive electrode active material layer contains a binder, the proportion of the binder in the positive electrode active material layer is selected from, for example, about 0.1% by mass or more (for example, 0.2% by mass or more). It may be 0.3% by mass or more (for example, 0.4% by mass or more), preferably 0.5% by mass or more (for example, 0.8% by mass or more), and more preferably 1% by mass or more (for example, 1). .2% by mass or more, 1.5% by mass or more, 1.8% by mass or more, 2% by mass or more, 2.2% by mass or more, 2.5% by mass or more, etc.).

When the positive electrode active material layer contains a binder, the upper limit of the proportion of the binder in the positive electrode active material layer is not particularly limited, but is, for example, 30% by mass, 29% by mass, 28% by mass, 27. Mass%, 26 mass%, 25 mass%, 24 mass%, 23 mass%, 22 mass%, 21 mass%, 20 mass%, 19 mass%, 18 mass%, 17 mass%, 16 mass%, 15 mass% , 14% by mass, 13% by mass, 12% by mass, 11% by mass, 10% by mass, 9% by mass, 8% by mass or less, 7% by mass, 6% by mass, 5% by mass, 4% by mass, etc. Good.

The coating mass of the positive electrode active material layer is not particularly limited, and may be, for example, 1 mg / cm ² or more (for example, 1 to 5 mg / cm ² ). In particular, in the present invention, the coating mass of the positive electrode active material layer is applied in a relatively large amount, for example, 5 mg / cm ² or more (for example, 6 mg / cm ² or more, 7 mg / cm ² or more, 8 mg / cm ² or more, 9 mg / cm / About cm ² or more, usually 10 mg / cm ² or more (for example, 12 mg / cm ² or more), preferably 15 mg / cm ² or more (for example, 16 mg / cm ² or more), and more preferably 17 mg / cm ² or more (for example). , 18 mg / cm ² or more), 19 mg / cm ² or more, 20 mg / cm ² or more, 21 mg / cm ² or more, 22 mg / cm ² or more, 23 mg / cm ² or more, 24 mg / cm ² or more, 25 mg / Cm ² or more, 28 mg / cm ² or more, 30 mg / cm ² or more, 32 mg / cm ² or more, 35 mg / cm ² or more, 38 mg / cm ² or more, 40 mg / cm ² or more, 42 mg / cm ² or more, 45 mg / cm ^{It can be 2} or more, 48 mg / cm ² or more, 50 mg / cm ² or more, and the like.

By setting such a relatively large coating mass, it seems that it is easy to efficiently obtain the improvement or improvement effect of the discharge capacity by the carbonaceous coated inorganic solid oxide. The reason for this is not clear, but the larger the coating mass, the larger the concentration gradient of the positive electrode active material or its ions (for example, lithium ions) in the positive electrode active material layer as described above, and therefore, the charge / discharge capacity. The degree of decline is also expected to be greater. However, it is considered that the effect of improving the charge / discharge capacity is more remarkable because the concentration gradient can be efficiently suppressed or relaxed by blending the inorganic solid oxide coated with carbonaceous material.

The upper limit of the coating mass of the positive electrode active material layer is not particularly limited, but is, for example, 200 mg / cm ² , 180 mg / cm ² , 150 mg / cm ² , 120 mg / cm ² , 100 mg / cm ² , 90 mg / cm. ² , 80 mg / cm ² , 70 mg / cm ² , 60 mg / cm ² , 55 mg / cm ² , 50 mg / cm ² , 45 mg / cm ² , 40 mg / cm ² , 35 mg / cm ² , 30 mg / cm ^2, etc. You may.

The thickness of the positive electrode active material layer can be appropriately selected according to the ratio of each component in the positive electrode active material layer, but may be selected from a range of about 10 μm or more (for example, 12 μm or more), for example, 15 μm or more (for example, 12 μm or more). , 15 μm or more), preferably 20 μm or more (for example, 21 μm or more), more preferably 25 μm or more (for example, 26 μm or more), and 30 μm or more (for example, 35 μm or more, 38 μm or more, 40 μm or more, 42 μm or more). , 45 μm or more, 48 μm or more, 50 μm or more, etc.).

The upper limit of the thickness of the positive electrode active material layer is not particularly limited, but may be, for example, 500 μm, 300 μm, 250 μm, 200 μm, 180 μm, 150 μm, 120 μm, 100 μm, 80 μm, 70 μm, 60 μm, 50 μm, 40 μm, or the like. Good.

The electrode density of the positive electrode active material layer (positive electrode) is, for example, 2 g / cc or more (for example, 2.1 g / cc or more, 2.4 g / cc or more), preferably 2.5 g / cc or more (for example, 2.6 g). / Cc or more, 2.9 g / cc or more), more preferably 3.0 g / cc or more (for example, 3.1 g / cc or more) or the like.

The upper limit of the electrode density of the positive electrode active material layer (positive electrode) is not particularly limited, but for example, 4 g / cc, 3.9 g / cc, 3.8 g / cc, 3.7 g / cc, 3.6 g / cc, etc. It may be.

(Method of forming positive electrode active material layer and positive electrode)
The positive electrode active material layer can be formed, for example, by using a positive electrode mixture (positive electrode material) (typically, by coating (coating)). Such a positive electrode mixture contains a constituent component of the positive electrode active material layer.

That is, the positive electrode mixture may contain a carbonaceous coated inorganic solid oxide (first conductive auxiliary agent, first conductive material), and usually further, a positive electrode active material (further, a conductive auxiliary agent) may be further contained. (Second conductive auxiliary agent, second conductive material), other components such as a binder) may be contained.

The positive electrode mixture may contain a solvent depending on the method for forming the positive electrode active material layer. In the positive electrode mixture containing such a solvent, each component may be in a state of being dissolved in the solvent or in a state of being dispersed in the solvent.

The solvent (solvent for dispersing or dissolving each component) is not particularly limited, and each conventionally known material can be used. For example, a nitrogen-containing solvent [for example, lactams (for example, N-methylpyrrolidone), amides) (Or chain amides, such as dimethylformamide, dimethylacetamide)], ketones [eg, chain ketones (eg, acetone, methylethylketone, etc.)], ethers [eg, cyclic ethers (eg, tetrahydrofuran, etc.) ) Etc.], alcohols (eg, ethanol, etc.), esters (eg, ethyl acetate, etc.), carbonates (eg, ethylene carbonate, propylene carbonate, diethyl carbonate, etc.), water and the like. The solvent may be used alone or in combination of two or more.

The amount of the solvent used is not particularly limited, and may be appropriately determined according to the production method and the material used.

In the positive electrode mixture containing a solvent, the ratio (concentration) of the solid content (components other than the solvent) is, for example, 10% by mass or more (for example, 11% by mass or more, 15% by mass or more), preferably 20% by mass or more ( For example, it may be about 21% by mass or more, 25% by mass or more), and more preferably about 30% by mass or more (for example, 31% by mass or more, 35% by mass or more). The upper limit of the ratio (concentration) is not particularly limited, but may be, for example, 99% by mass, 95% by mass, 90% by mass, 85% by mass, 80% by mass, or the like.

The positive electrode active material layer can be formed by using a positive electrode mixture. The positive electrode may usually include a positive electrode active material layer and a positive electrode current collector (a positive electrode active material layer formed on the positive electrode current collector). Such a positive electrode active material layer may typically form a positive electrode active material layer by applying (coating) a positive electrode mixture to a positive electrode current collector.

The material of the positive electrode current collector is not particularly limited, and for example, a conductive metal such as aluminum, aluminum alloy, SUS (stainless steel), or titanium can be used.

The shape of the positive electrode (positive electrode current collector) is not particularly limited, but may be, for example, a sheet shape (may be formed into a sheet shape).

The method for forming the positive electrode active material layer (coating method) is not particularly limited, and for example, (i) the positive electrode mixture is applied to the positive electrode current collector by a conventional coating method (for example, the doctor blade method) (furthermore. Method of (drying), (ii) method of immersing (further drying) the positive electrode current collector in the positive electrode mixture, (iii) joining the sheet formed of the positive electrode mixture to the positive electrode current collector (for example, conductive adhesion). A method of joining through an agent) and pressing (further drying), (iv) a positive electrode mixture to which a liquid lubricant is added is applied or cast on a positive electrode current collector, and then formed into a desired shape. , A method of removing the liquid lubricant (and then stretching in the uniaxial or multiaxial direction), (v) Positive electrode active material layer of positive electrode mixture (or positive electrode active material, inorganic solid oxide, conductive auxiliary agent, etc.) (Solid content) is slurried with an electrolytic solution, transferred to a current collector (positive electrode current collector) as a semi-solid state, and used as an electrode (positive electrode) without being dried.

The positive electrode mixture (positive electrode active material layer) may be dried or pressed (pressed) after being formed or coated (coated), if necessary.

In such a method [coating (coating process)], by setting (adjusting) the coating mass within the above range, more efficiently, discharge by the carbonaceous coated inorganic solid oxide. It seems that it is easy to efficiently obtain the improvement or improvement effect of the capacity.

[Use of positive electrode]
The positive electrode can be used, for example, in a battery (a battery having a charge / discharge mechanism), a storage (electrochemical) device (or a material of an ionic conductor constituting them), or the like.

Specifically, the positive electrode constitutes, for example, a primary battery, a secondary battery (for example, a lithium (ion) secondary battery), a fuel cell, an electrolytic capacitor, an electric double layer capacitor, a solar cell, an electrochromic display element, and the like. Can be used as a positive electrode.

Hereinafter, a battery (particularly a lithium ion secondary battery) will be described as an example. The battery includes at least a positive electrode and a negative electrode.

(Negative electrode)
The negative electrode contains a negative electrode active material, and a negative electrode active material layer may be formed. Such a negative electrode may be composed of the negative electrode active material itself (for example, lithium metal or the like), or may be composed of a negative electrode current collector and a negative electrode active material layer. Such a negative electrode active material layer is formed, for example, by using a negative electrode mixture (negative electrode mixture containing a negative electrode active material) [for example, by coating (coating) a negative electrode mixture (negative electrode active material composition)]. To. More specifically, the negative electrode active material layer [or the negative electrode mixture containing the negative electrode active material (negative electrode active material composition)] is formed in the form of a negative electrode current collector (supported on the negative electrode current collector). It may be present, and usually, it may be formed into a sheet.

As the negative electrode active material, a conventionally known negative electrode active material or the like used in various batteries (for example, a lithium secondary battery) or the like can be used, and various ions (for example, lithium ions) can be occluded and released. All you need is.

Specifically, graphite materials such as artificial graphite and natural graphite, mesophase calcined products made from coal and petroleum pitch, carbon materials such as non-graphitizable carbon, Si-based negative electrode materials such as Si, Si alloy and SiO, Sn. Sn-based negative electrode materials such as alloys and lithium alloys such as lithium metal and lithium-aluminum alloy can be used. The negative electrode active material may be used alone or in combination of two or more.

The negative electrode mixture may further contain a conductive auxiliary agent (conductive substance), a binder, a solvent and the like. As the conductive auxiliary agent, the binder, the solvent and the like, the same components as described above can be used. Further, the usage ratio and the like are the same as described above.

The negative electrode (or the negative electrode mixture) may contain a carbonaceous coated inorganic solid oxide or an inorganic solid oxide that is not carbonaceous coated, but from the viewpoint of battery performance, it is (substantially) contained. You don't have to.

As the material of the negative electrode current collector, for example, a conductive metal such as copper, iron, nickel, silver, or stainless steel (SUS) can be used.

As a method for manufacturing the negative electrode, the same method as the method for manufacturing the positive electrode may be adopted.

(Electrolytic solution)
The battery may include an electrolyte. The electrolyte contains at least an electrolyte. The electrolyte is not particularly limited, and the electrolyte used in the electrolytic solution can be used. The electrolytic solution may be contained in the positive electrode active material layer or the positive electrode mixture.

As such an electrolyte, a salt of an anion and a cation (electrolyte salt) can be appropriately selected depending on the purpose of use and the like.

The anionic, for example, boron ions _{^{[e.g., BF 4 -, BF (CF}} 3) 3 -, B (CN) 4 -, B 12 F 12-x H x ( wherein, X is a number less than 12) Etc.], phosphorus-based ions {for example, PF ₆ ⁻ , PF _m (C _n F _{2n + 1} ) _{6 − m} ⁻ (in the formula, m indicates 1 to 5 and n indicates 1 or more) [for example, ^{_{PF 3 (CF 3) 3 -}} , PF 3 (C 2 F 5) 3 -, PF 3 (C 3 F 7) 3 -, PF 3 (C 4 F 9) 3 - and the like], _{PF 2 O} 2 ^-, etc. }, antimony-based ion (e.g., SbF ₆ ^-, etc.), arsenic ions (e.g., AsF ₆ ^-, etc.), perchloric acid ion (ClO ₄ ^-), thiocyanate ion (NCS ^-), aluminum-based ions (e.g., AlCl ₄ ^-, AlF ₄ ^-, etc.), sulfonic acid-based ion ^{_{(e.g., CF 3 SO 3 -, FSO}} 3 - , etc.), methide ion _{(e.g., C [(CF 3 SO 2} ) 3] - , etc.), dinitro Amin anion ((O ₂ N) ₂ N ⁻ ), cyanamide ion (eg N [(CN) ₂ ] ⁻ etc.), triazolate ion (eg dicyanotriazolate ion etc.), imide ion {eg fluorosulfonyl Imidion [eg, bis (fluorosulfonyl) imide ion; (fluorosulfonyl) (fluoroalkylsulfonyl) imide (eg, fluorosulfonyl) (fluoroalkylsulfonyl) imide such as (fluorosulfonyl) (trifluoromethylsulfonyl) imide, (fluorosulfonyl) (pentafluoroethylsulfonyl) imide. Fluorosulfonyl) (fluoroC _1-6 alkylsulfonyl) imide) ions], fluoroalkylsulfonylimide ions [eg, bis (fluoroalkylsulfonyl) imides such as bis (trifluoromethylsulfonyl) imide, bis (pentafluoroethylsulfonyl) imide) ) Idions (eg, ions such as bis (fluoroC _1-6 alkylsulfonyl) imides)] and other fluorine-containing sulfonylimide ions} and the like.

Examples of the cation include metal ions [or metal cations, for example, alkali metal ions (for example, lithium ion, sodium ion, potassium ion, rubidium ion, cesium ion, etc.), alkaline earth metal ions (for example, beryllium ion, magnesium). Ions, calcium ions, strontium ions, barium ions, etc.), aluminum ions, etc.], ammonium ions (eg, tetraethylammonium ions, triethylmethylammonium ions, etc., quaternary ammonium ions), phosphonium ions (eg, tetramethylphosphonium ions, etc.) (Quadrant phosphonium ion) and the like.

In the electrolyte, the combination of the anion and the cation is not particularly limited, and any combination of the above anion and the cation may be used (the salt may be formed by any combination).

Specific electrolytes include, for example, lithium salts [for example, LiBF ₄ , LiBF (CF ₃ ) ₃ , LiB ₁₂ F _12-x H _x , LiPF ₆ , LiPF ₃ (CF ₃ ) ₃ , LiPF ₃ (C ₂ F). ₅ ) ₃ , LiPF ₃ (C ₃ F ₇ ) ₃ , LiPF ₃ (C ₄ F ₉ ) ₃ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiSCN, LiAlF ₄ , CF ₃ SO ₃ Li, LiC [(CF _{3) 2} ) ₃ ], LiN (NO ₂ ), LiN [(CN) ₂ ], FSO ₃ Li, PF ₂ O ₂ Li, Lithium bis (fluorosulfonyl) imide (LiFSI), Lithium bis (trifluoromethylsulfonyl) imide, Lithium bis (pentafluoroethylsulfonyl) imide, etc.], non-lithium salts [for example, salts in which lithium (ion) is replaced with another metal (ion) in these lithium salts (eg, NaBF ₄ , NaPF ₆ , NaPF ₃ (eg, NaPF ₄ , NaPF ₆ ) CF ₃ ) ₃ , sodium bis (fluorosulfonyl) imide, sodium bis (trifluoromethylsulfonyl) imide, sodium bis (pentafluoroethylsulfonyl) imide, etc.)] etc.} can be mentioned. The electrolyte may be used alone or in combination of two or more.

Among these, LiPF ₆ , LiFSI and the like are particularly preferable. Such an electrolyte has high ionic conductivity, and when combined with an inorganic solid oxide coated with a carbonaceous material (furthermore, a positive electrode active material layer having a relatively large coating mass), it can efficiently charge / discharge capacity and the like. It seems easy to improve or improve.

The electrolytic solution may contain a solvent. The solvent is not particularly limited and can be selected depending on the intended use, for example, chain carbonate [for example, dialkyl carbonate (for example, dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), etc. DiC _1-4 alkyl carbonate), alkylaryl carbonate (eg, C _1-4 alkylphenyl carbonate such as methylphenyl carbonate), diaryl carbonate (eg, diphenyl carbonate), etc.], cyclic carbonate [eg, saturated cyclic carbonate (eg, saturated cyclic carbonate). , Ethylene carbonate (EC), propylene carbonate (PC), 2,3-dimethylethylene carbonate, alkylene carbonates such as 1,2-butylene carbonate (eg, C _2-6 alkylene carbonate), erythritan carbonate, etc., unsaturated Cyclic carbonate (eg, alkenylene carbonate such as vinylene carbonate, methyl vinylene carbonate, ethyl vinylene carbonate; 2-vinylcarbonate ethylene), fluorine-containing cyclic carbonate (eg, fluoroethylene carbonate, 4,5-difluoroethylene carbonate, trifluoropropylene carbonate) ) Etc.] and other carbonates; chain ethers [eg, alkanediol dialkyl ether (eg, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, etc.), polyalkanediol dialkyl ether (eg, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl, etc.) Ether), etc.], cyclic ethers [eg, tetrahydrofurans (eg, tetrahydrofuran, 2-methyltetra, 2,6-dimethyl tetrahydrofuran), tetrahydropyrans (eg, tetrahydropyran), dioxans (eg, 1, Ethers such as 4-dioxane), dioxolanes (eg, 1,3-dioxolane), crown ether, etc.; Chain esters [eg, aromatic carboxylic acid esters (eg, methyl benzoate, ethyl benzoate) Etc.], cyclic esters [or lactones such as γ-butyrolactone, γ-valerolactone, δ-valerolactone, etc.] and other esters (carboxylic acid esters); alkyl phosphate esters (eg, trimethyl phosphate, phosphorus) Phosphate esters such as ethyldimethyl acid acid, diethylmethyl phosphate, triethyl phosphate); aliphatic nitriles (eg) For example, acetonitrile, propionitrile, methoxypropionitrile, glutaronitrile, adipionitrile, 2-methylglutaronitrile, valeronitrile, butyronitrile, isobutyronitrile, etc.), aromatic nitriles (eg, benzonitrile, tolnitrile) Nitriles such as; sulfur-containing solvents such as sulfones (eg, dimethylsulfone, ethylmethylsulfone, diethylsulfone, etc.), sulfolanes (eg, sulfolane, 3-methylsulfone, 2,4-dimethylsulfone); nitromethane, 1, , 3-Dimethyl-2-imidazolidinone, 1,3-dimethyl-3,4,5,6-tetrahydro-2 (1H) -pyrimidinone, 3-methyl-2-oxazolidinone and the like. The solvent may be used alone or in combination of two or more.

Among these solvents, carbonates, ethers, esters and the like are typical, and in particular, chain carbonates (eg, dimethyl carbonate, ethylmethyl carbonate, diethyl carbonate) and cyclic carbonates (eg, ethylene carbonate, propylene carbonate) are typical. ), A lactone (for example, γ-butyrolactone, γ-valerolactone) and the like may be preferably used.

When the electrolytic solution contains a solvent, the ratio (concentration) of the electrolyte in the electrolytic solution is not particularly limited, but is, for example, 0.5 M (mol / L) or more (for example, 0.6 M or more, 0.7 M or more, etc.). It may be preferably about 0.8 M or more (for example, 0.9 M or more), more preferably about 1 M or more (for example, 1.1 M or more), and 5 M or less (for example, 4 M or less, 3.5 M or less, 3 M or less). Below, 2.5M or less, 2M or less, 1.5M or less, 1M or less, 0.8M or less) and the like may be used.

The electrolytic solution containing a solvent may usually be a non-aqueous electrolytic solution (an electrolytic solution containing substantially no water).

(Separator)
The battery may include a separator. The separator is arranged so as to separate the positive electrode and the negative electrode. The separator is not particularly limited, and in the present invention, any conventionally known separator can be used. Specific examples of the separator include a porous sheet made of a polymer capable of absorbing and retaining an electrolytic solution (non-aqueous electrolytic solution) (for example, a polyolefin-based microporous separator, a cellulose-based separator, etc.), a non-woven fabric separator, and a porous material. Examples include metal bodies.

Examples of the material of the porous sheet include a laminate having a three-layer structure of polyethylene, polypropylene, and polypropylene / polyethylene / polypropylene.

Examples of the material of the non-woven fabric separator include cotton, rayon, acetate, nylon, polyester, polypropylene, polyethylene, polyimide, aramid, glass, etc., and the above-exemplified materials may be used according to the required mechanical strength and the like. It may be used alone or in combination of two or more.

(Battery exterior material)
A battery element including an electrolytic solution, a positive electrode, a negative electrode (further, a separator) and the like is usually housed in a battery exterior material in order to protect the battery element from external impact, environmental deterioration, etc. when the battery is used. The material of the battery exterior material is not particularly limited, and any conventionally known exterior material can be used.

The shape of the battery (lithium ion secondary battery, etc.) is not particularly limited, and any conventionally known shape as the shape of the battery (lithium ion secondary battery, etc.) such as cylindrical type, square type, laminated type, coin type, large size, etc. Can also be used. Further, when used as a high-voltage power source (several tens of volts to several hundreds of volts) for mounting on an electric vehicle, a hybrid electric vehicle, or the like, the battery module may be configured by connecting individual batteries in series. ..

The rated charging voltage of the secondary battery (lithium ion secondary battery, etc.) is not particularly limited, but is 3.6 V or more, preferably 4.1 V or more, and more preferably 4.2 V or more (for example, more than 4.2 V). It may be 4.3V or more (for example, 4.35V or more). The higher the rated charging voltage is, the higher the energy density can be. However, from the viewpoint of safety, the rated charging voltage may be 4.6 V or less (for example, 4.5 V or less).

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.

Example 1 (Carbonaceous Coat BaTIO ₃ )
Weigh 1 g of BaTIO ₃ (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd. 025-08972), add 0.2 g of phloroglucinol (manufactured by Tokyo Chemical Industry Co., Ltd.) to it, add acetone to dissolve phloroglucinol, and perform ultrasonic treatment. Then, it was dried to obtain an inorganic solid oxide-phloroglucinol mixture.

The inorganic solid oxide-phloroglucinol mixture was carbonized in nitrogen at 300 ° C. for 1 hour, and then the excess carbon components were washed with NMP (N-methylpyrrolidone). After washing, it was further calcined in nitrogen at 700 ° C. for 2 hours. The obtained powder was carbonaceous coated (carbon coated) and had a black tinge.

The proportion of carbonaceous material in the obtained powder [carbonaceous coated inorganic solid oxide (BaTIO ₃ )] was 0.19% by mass.

The results of Raman analysis of the obtained carbonaceous coated inorganic solid oxide are shown in FIG. According to this, it can be seen that the D, G, G', D + D', and 2D' bands peculiar to amorphous carbon are present, the carbonaceous substance is present, and the carbonaceous state is amorphous carbon.

The ratio of carbonaceous material was calculated by TGA analysis (apparatus: TG8120 manufactured by Rigaku Co., Ltd.) under the conditions: under air, heating rate 10 ° C./min, maximum temperature 700 ° C., and weight loss.

In addition, Raman analysis (confirmation of the existence and state of carbonaceous materials) was performed as follows.
Measuring device: Microscopic Raman (JASCO NRS-3100)
Measurement conditions: 532 nm laser used, objective lens 20 times, CCD capture time 1 second, integration 32 times (resolution = 4 cm ^-1 )
From Raman analysis, G band (within the range of 1550 cm ^{-1 to} 1650 cm ^-1 ), D band (within the range of 1300 cm ^{-1 to} 1400 cm ^-1 ), G'band (within the range of 2650 cm ^{-1 to} 2750 cm ^-1 ), D + D 'band ⁽ⁱⁿ the range of 2800cm ^-1 ~3000cm -1), 2D' reveals the presence and condition of carbonaceous by the presence of the band ⁽ⁱⁿ the range of 3100cm ^-1 ~3300cm -1).

Example 2 (Carbonaceous Coat SrTiO ₃ )
In Example 1, powder was obtained in the same manner as in Example 1 except that SrTiO ₃ (51711-50G manufactured by Aldrich) was used instead of BaTiO ₃ . The obtained powder was carbon-coated and had a black tinge.

The proportion of carbonaceous material in the obtained powder [carbonaceous coated inorganic solid oxide (SrTIO ₃ )] was measured and calculated in the same manner as in Example 1 and found to be 1.4% by mass.

Further, Raman analysis of the obtained carbonaceous coated inorganic solid oxide was performed in the same manner as in Example 1. The results are shown in FIG. According to this, it can be seen that the D, G, G', D + D', and 2D' bands peculiar to amorphous carbon are present, the carbonaceous substance is present, and the carbonaceous state is amorphous carbon.

Example 3 (Carbonaceous Coat LiNbO ₃ )
Powder was obtained in the same manner as in Example 1 except that LiNbO ₃ (254290-10G manufactured by Aldrich) was used instead of BaTiO ₃ . The obtained powder was carbon-coated and had a black tinge.

The results of Raman analysis of the obtained powder [carbonaceous coated inorganic solid oxide (LiNbO ₃ )] in the same manner as in Example 1 are shown in FIG. According to this, it can be seen that the D, G, G', D + D', and 2D' bands peculiar to amorphous carbon are present, the carbonaceous substance is present, and the carbonaceous state is amorphous carbon.

The amount of carbonaceous (coating amount) was smaller than that of the inorganic solid oxide, and the amount of carbonaceous could not be calculated by TGA analysis (it was below the lower limit of analysis), but as mentioned above, Raman. The presence of carbonaceous material was confirmed by analysis.

Example 4 (Comparison of presence / absence of carbonaceous coating)
LiCoO ₂ (KD20S manufactured by Yumicore) as the positive electrode active material, the carbon-coated inorganic solid oxide (BaTIO ₃ , the first conductive auxiliary agent) obtained in Example 1, and the conductive auxiliary agent (the second conductive auxiliary agent). , Acetylene black (HS-100 manufactured by Denka Kogyo), carbon nanotubes (VGCF Showa Denko), carbon fiber (Donna Carbomilled manufactured by Osaka Gas Chemical Co., Ltd.), polyvinylidene fluoride (PVDF Kureha # 1120) as a binder, inorganic solid oxide As SrTIO ₃ (51711-50G manufactured by Aldrich) was used.

LiCoO ₂ : Carbonaceous coated inorganic solid oxide (BaTIO ₃ ): Acetylene black:
Weighed at a mass ratio of VGCF: Donna Carbomiled: PVdF = 93: 1: 1: 1: 1: 3, added N-methylpyrrolidone (NMP) and dispersed with a rotating revolution mixer to contain an inorganic solid oxide. A positive electrode slurry (positive electrode mixture, solid content concentration 75% by mass) was prepared.

Similarly, a positive electrode slurry containing a mass ratio of LiCoO ₂ : acetylene black: VGCF: donacarbomilled: PVdF = 94: 1: 1: 1: 3 and containing no carbonaceous coated inorganic solid oxide was prepared.

Further, similarly, at a mass ratio of LiCoO ₂ : uncoated inorganic solid oxide (BaTIO ₃ ): acetylene black: VGCF: donacarbomiled: PVdF = 93: 1: 1: 1: 1: 3. A positive electrode slurry containing, containing, and containing no carbonaceous coated inorganic solid oxide (containing uncarbonated inorganic solid oxide (BaTIO ₃ )) was prepared.

Each slurry was coated on one side of an aluminum foil, dried on a hot plate at 110 ° C., and then dried under reduced pressure in a vacuum drying oven at 110 ° C. for 12 hours. Then, after vacuum drying, each was pressed with a roll press machine. The press was performed by adjusting the roll press machine so that the electrode density was in the range of 3.35 g / cc to 3.5 g / cc.

In this way, an electrode having a positive electrode active material layer having a single-sided coating mass of 53.50 mg / cm ² (thickness 151 μm) was produced.

Li metal was punched with a diameter of 14 mm to form a negative electrode. On top of that, 35 μL of an electrolytic solution having a composition of 1.2 M LiPF ₆ ethylene carbonate (EC) / ethyl methyl carbonate (EMC) = 3/7 (volume ratio) was added dropwise, and a 16 μm separator made of polyethylene (PE) was overlaid. 35 μL of the electrolytic solution was added dropwise. A coin cell was prepared by laminating the prepared electrode, which was punched to φ12 mm, as a positive electrode.

The obtained coin cell was charged and discharged at 4.3 V, 0.1 C constant current constant voltage charge for 15 hours, and 0.1 C constant current discharge 3.0 V termination, and the cell was aged.

The cell after aging was charged at a constant current constant voltage of 4.3 V and 0.2 C for 8 hours, and discharged at a constant current of 0.1 C and 3.0 V at the end.

In the same charging method, 0.2C, 3.0V termination constant current discharge, 1C, 3.0V termination constant current discharge, 1.25C, 3.0V termination constant current discharge are performed, and a total of 4 cycles after aging. went.

At 0.1 C discharge, 0.2 C discharge, and 1 C discharge, the closed circuit voltage was measured 2 seconds after the start of discharge, and the gradient was calculated from the relationship between the current and the closed circuit voltage, and calculated as the DCR (DC resistance value) of the cell.

Table 1 shows the results including the discharge capacity per active material of the electrode. In Table 1, the 1C discharge capacity and DCR are relative values with the value when the inorganic solid oxide is not added set to "100.0".

As is clear from the results in Table 1, it was shown that the addition of the carbonaceous coated inorganic solid oxide (BaTIO ₃ ) increased the discharge capacity and improved the battery performance.

In addition, the carbonaceous coated inorganic solid oxide has a resistance value equal to or lower than that when the inorganic solid oxide is not blended (instead, the same amount of acetylene black is used), probably because it exhibits conductivity by itself. showed that.

In this way, it is extremely surprising that the discharge capacity could be improved without impairing the conductivity even though it was coated with carbonaceous material.

On the other hand, even when the carbonaceous coating was not performed, the discharge capacity was unexpectedly increased under the above conditions, but the resistance value was increased.

Example 5 (different inorganic solid oxide)
In the same manner as in Example 4, except that in Example 4, any of the carbonaceous coated inorganic solid oxides obtained in Examples 2 and ₃ was used instead of the carbonaceous coated BaTiO ₃ . The relative values of 1C discharge capacity and DCR (relative values with the value when no inorganic solid oxide was added were set to "100.0") were measured. The results are shown in Table 2.

As is clear from the results in Table 2, the same tendency was observed even when the type of the inorganic solid oxide was changed.

Example 6 (Change of coating mass)
1C in the same manner as in Examples 4 and 5 except that the coating mass was changed to 43.67 mg / cm ² (thickness 127 μm) or 28.80 mg / cm ² (thickness 84 μm) in Examples 4 and 5. The relative values of the discharge capacity and DCR (relative values with the value when no inorganic solid oxide was added were set to "100.0") were measured. The results are shown in Tables 3 and 4, respectively.

As is clear from the results in Tables 3 and 4, the same tendency was observed even when the coating mass was changed.

Example 7 (Change of coating mass and inorganic solid oxide)
In Example 4, the coating mass was further reduced to 19.43 mg / cm ² (thickness 57 μm) or 24.12 mg / cm ² (thickness 70 μm), or the type of carbonaceous coated inorganic solid oxide was changed. Except for this, the relative values of 1C discharge capacity and DCR (relative values with the value when no inorganic solid oxide was added was “100.0”) were measured in the same manner as in Example 4. The results are shown in Table 5.

As is clear from the results in Table 5, the same tendency was observed even when the coating mass was further reduced and the type of the inorganic solid oxide was changed.

Example 8 (change of electrolytic solution)
Except that in Examples 4 and 5, the electrolytic solution was an electrolytic solution having an EC / MEC = 3/7 (volume ratio) composition containing LiPF ₆ (concentration 0.6M) and LiFSI (concentration 0.6M). In the same manner as in Examples 4 and 5, the relative values of 1C discharge capacity and DCR (relative values with the value when no inorganic solid oxide was added were set to "100.0") were measured [coating mass 53.50 mg. / Cm ² (thickness 151 μm)]. The results are shown in Table 6.

As is clear from the results in Table 6, it was found that the same tendency was observed even when an electrolytic solution in which a part of LiPF ₆ was replaced with LiFSI having higher ionic conductivity was used. Further, as is clear from the comparison with the results of Examples 4 and 5, by using LiFSI having a higher ionic conductivity, the effect of improving the discharge capacity and the effect of reducing the resistance were larger.

Example 9 (Change of carbonaceous material)
Polyvinyl alcohol (PVA) was dissolved in pure water heated to 70 ° C. to prepare an aqueous solution of 2% by mass of polyvinyl alcohol. In this aqueous solution, the inorganic solid oxides (BaTIO ₃ , SrTIO ₃ , and LiNbO ₃ ) used in Examples 1 to ₃ were added so as to have a mass ratio of polyvinyl alcohol: inorganic solid oxide = 1:10, respectively. Each was weighed and dispersed at 2000 rpm for 5 minutes with a rotating and revolving mixer. The obtained slurry was dropped onto a polytetrafluoroethylene (PTFE) sheet and dried on a hot plate at 110 ° C. to obtain a polyvinyl alcohol-coated inorganic solid oxide. This was calcined at 700 ° C. for 2 hours in a nitrogen atmosphere to obtain a carbonaceous coated inorganic solid oxide.

The ratio of carbonaceous material in the obtained carbonaceous coated inorganic solid oxide was measured in the same manner as in Example 1 and found to be 0.2% by mass to 1.1% by mass.

Further, in the same manner as in Example 1, the presence of carbonaceous (amorphous carbon) was confirmed by Raman analysis.

Example 10 (Change of carbonaceous material)
In Example 4, the relative values of 1C discharge capacity and DCR (values when no inorganic solid oxide is added) are the same as in Example 4 except that the carbonaceous coated BaTiO ₃ prepared in Example 9 is used. (Relative value with “100.0”) was measured [coating mass 53.50 mg / cm ² (thickness 151 μm)]. The results are shown in Table 7.

As is clear from the results in Table 7, it was found that there is a similar tendency even when the carbonaceous material is PVA.

Example 11 (Change of carbonaceous material and coating mass)
In Example 10, the carbonaceous coat BaTiO ₃ , the carbonaceous coat SrTiO ₃ or the carbonaceous coat LiNbO ₃ prepared in Example 9 was used, and the coating mass was changed to 19.43 mg / cm ² (thickness 57 μm). Except for this, the relative values of 1C discharge capacity and DCR (relative values with the value when no inorganic solid oxide was added was “100.0”) were measured in the same manner as in Example 10. The results are shown in Table 8.

As is clear from the results in Table 8, it was found that the same tendency was observed even when the carbonaceous material was PVA and the coating mass was changed.

Example 12 (LiNbO ₃ , average particle diameter 1 μm, coating mass 20 mg / cm ² )
LiCoO ₂ (KD20S manufactured by Yumicore) as a positive electrode active material, acetylene black (HS-100 manufactured by Denka Industries) as a conductive auxiliary agent, carbon nanotubes (VGCF Showa Denko), polyvinylidene fluoride (KF polymer # 1120 manufactured by PVDF Kureha) as a binder. Was used. Further, in the same manner as in Example 3 except that LiNbO ₃ (manufactured by HC Stark, average particle diameter 1 μm) was used as the inorganic solid oxide, the powder [carbonaceous coated inorganic solid oxide (LiNbO) was used. ₃ )] was used. The obtained powder was carbon-coated and had a black tinge. Further, in the same manner as in Example 1, the presence of carbonaceous (amorphous carbon) was confirmed by Raman analysis.

LiCoO ₂ : Acetylene black: VGCF: PVDF: Carbonic coat LiNbO ₃ = 90.5: 3: 2: 3: 1.5 Weighed at a mass ratio, added N-methylpyrrolidone (NMP), and used a rotation / revolution mixer. The mixture was dispersed to prepare a positive electrode slurry containing a carbonaceous coat LiNbO ₃ .

Similarly, a positive electrode slurry containing LiNbO ₃ without carbon coating having the same composition was prepared.

Each positive electrode slurry was coated on one side of an aluminum foil, dried on a hot plate at 110 ° C., and then dried under reduced pressure in a vacuum drying oven at 110 ° C. for 12 hours. Then, after vacuum drying, each was pressed with a roll press machine. For the press, the roll press machine was adjusted so that the electrode density was 3.6 g / cc.

In this way, an electrode having a positive electrode mixture layer having a single-sided coating mass of 20 mg / cm ² (thickness 70 μm) was produced.

Graphite (SMG manufactured by Hitachi Chemical) as the negative electrode active material, carbon nanotube (VGCF Showa Denko) as the conductive auxiliary agent, styrene-butadiene rubber (SBR, JSR) as the binder, and carboxymethyl cellulose (CMC Dycel) as the thickener. Using.

A 2% aqueous solution of CMC was prepared, weighed at a mass ratio of graphite: VGCF: CMC: SBR = 100: 2: 1: 1, and dispersed with a rotation / revolution mixer to prepare a negative electrode slurry.

The negative electrode slurry was coated on one side of a copper foil, dried on a hot plate at 80 ° C., and then dried under reduced pressure in a vacuum drying oven at 100 ° C. for 12 hours. Then, after vacuum drying, the electrodes were pressed with a roll press so that the electrode density was 1.5 g / cc.

In this way, an electrode having a negative electrode mixture layer having a single-sided coating mass of 9.6 mg / cm ² was produced.

(Making laminated batteries)
The positive electrode and the negative electrode obtained above were cut, and the polarity lead-out lead was ultrasonically welded, the positive electrode and the negative electrode were opposed to each other via a 25 μm PE separator, and three sides were sealed with a laminated exterior. 700 μL of electrolytic solution was added from the unsealed one. As a result, a 4.2 V, 30 mAh laminated battery (full cell) was produced.

As the electrolytic solution, an electrolytic solution having an EC / MEC = 3/7 (volume ratio) composition containing LiPF ₆ (concentration 0.6M) and LiFSI (concentration 0.6M) was used.

The obtained laminated battery is charged with a constant current constant voltage of 4.2 V and 0.5 C for 5 hours, then discharged with a constant current of 0.2 C and 2.75 V, and further charged at 1 C and 2.75 V. The constant current was discharged up to, and the cell was aged.

(1C discharge capacity)
After the aging was completed, the cell was charged at 4.2 V, 1 C (30 mA) at 25 ° C., and at the end of 0.6 mA, and then the discharge capacity was measured at 25 ° C. at 1 C, 2.75 V. After discharging, the same charging was performed at 25 ° C., the temperature was adjusted to −20 ° C. and left for 3 hours, and the discharge capacity of 1C and 2.75V was measured at −20 ° C. Table 9 shows the results including the discharge capacity per active material of the electrode.

As is apparent from the results shown in Table 9, although does not change the discharge amount at room temperature (25 ° C.), the discharge capacity of the load is a strong -20 ° C. was improved by the addition of LiNbO _3. Further, the carbon-coated LiNbO ₃ had a greater effect of improving the discharge capacity at −20 ° C. than the carbon-coated LiNbO ₃ .

(DCR (relative value))
Further, in the cell after the completion of aging, the relative value of DCR (value when no inorganic solid oxide is added is set to "100.0" at a charging depth (SOC) of 50% in the same manner as in Example 4. Value) was measured. The results are shown in Table 10.

As can be seen from the results in Table 10, the addition of LiNbO _3, the resistance value was reduced. Further, the carbon-coated LiNbO ₃ had a greater effect of reducing the resistance value than the carbon-uncoated LiNbO ₃ .

(Cycle capacity maintenance rate)
Further, the cell after the completion of aging was subjected to a cycle test of a total of 300 cycles at 45 ° C. under the following charge / discharge conditions (cycle conditions). The results are shown in Table 11.
(Cycle condition)
Charging: 4.2V, 1C, 0.6mA termination Discharge: 1C, 2.75V termination

As is clear from the results in Table 11, the addition of LiNbO ₃ improved the volume retention rate after 300 cycles. Further, the carbon-coated LiNbO ₃ had a greater effect of improving the cycle capacity retention rate than the carbon-uncoated LiNbO ₃ .

Example 13 (average particle size 1 μm or 100 to 300 μm, coating mass 90 mg / cm ² )
A 0.3 mm thick PP sheet was processed with a Thomson cutter to prepare a donut-shaped PP resin frame having an outer diameter of 6 cm × 6 cm and an opening of 4 cm × 4 cm at the center. ThreeBond 3315E was applied to one side of the PP resin frame as a sealant and an adhesive, attached to a 15 μm aluminum foil, and dried in a vacuum drying oven at 60 ° C. for 12 hours. After drying, one lead contact point was provided outside the PP resin frame, and the other metal current collectors were cut along the resin frame to prepare a positive electrode current collector.

As for the negative electrode current collector, a donut-shaped PP resin frame having a 0.3 mm thick PP sheet having a thickness of 6 cm × 6 cm and an opening of 4.2 cm × 4.2 cm at the center was produced in the same manner as the positive electrode current collector. .. ThreeBond 3315E was applied to one side of the PP resin frame as a sealant and an adhesive, and then attached to a copper foil of 15 μm and dried in the same manner as the positive electrode current collector to prepare a negative electrode current collector.

LiNi _1/3 Co _1/3 Mn _1/3 O ₂ (manufactured by Yumicore, MX7H) as positive electrode active material, acetylene black (manufactured by Denka Kogyo, HS-100) as conductive aid, carbon nanotubes (manufactured by VGCF Showa Denko), Carbon fiber (manufactured by Osaka Gas Chemicals: Donna Carbomilled) was used. Further, as an inorganic solid oxide, LiNbO ₃ (manufactured by HC Stark, average particle diameter 1 μm, hereinafter also referred to as “LiNbO ₃ (1 μm)”) or LiNbO ₃ (manufactured by Aldrich, 254290-10G, average particle diameter 100). A powder [carbonic coated inorganic solid oxide (LiNbO ₃ )] was used in the same manner as in Example 3 except that ~ 300 μm, hereinafter also referred to as “LiNbO ₃ (100 to 300 μm)”) was used. The obtained powder was carbon-coated and had a black tinge. Further, in the same manner as in Example 1, the presence of carbonaceous (amorphous carbon) was confirmed by Raman analysis.

Positive electrode active material: HS-100: VGCF: Donna carbomilled: Carbonaceous coat LiNbO ₃ is weighed at a mass ratio of 81: 5: 5: 5: 4, and the electrolytic solution is weighed so as to have a solid content of 70%. , A positive electrode slurry was prepared by dispersing with a rotation / revolution mixer. The electrolytic solution was an electrolytic solution having an EC / propylene carbonate (PC) = 3/7 (volume ratio) composition containing LiFSI (concentration 2M) and EC / PC = 3/7 (concentration 1M) containing LiPF ₆ (concentration 1M). An electrolytic solution blended with an electrolytic solution having a composition (volume ratio) at a volume ratio of 2: 1 was used.

The prepared positive electrode slurry was transferred to the opening of the positive electrode current collector so that the coating mass of the solid content was 90 mg / cm ² (thickness 200 μm), and a cellulose separator (manufactured by Nippon Advanced Paper Industry Co., Ltd., TF4425, thickness) was transferred. : 25 μm, non-woven fabric: porosity 71%) are placed on the positive electrode slurry in two layers, a SUS jig is placed on it, and a flat plate press (Tester Sangyo, SA-302) is used at a cylinder pressure of 30 MPa. Pressed for seconds. After the press, one sheet of the same separator as described above was further installed, and 0.4 g of the electrolytic solution was added dropwise to prepare a positive electrode.

Further, a positive electrode was prepared by slurrying (creating a positive electrode slurry) in the same manner as described above (with the same composition and electrolytic solution as described above) except that LiNbO ₃ without carbon coating was used.

Further, the same as above except that the positive electrode slurry containing no inorganic solid oxide was used, which contained a positive electrode active material: HS-100: VGCF: donacarbomilled = 85: 5: 5: 5. A positive electrode was prepared.

Hard carbon (Kureha, Carbotron P) as negative electrode active material, acetylene black (HS-100, Denka Kogyo), carbon nanotube (VGCF Showa Denko), carbon fiber (Osaka Gas Chemicals: Dona Carbomilled) as conductive aid Was used.

Negative electrode active material: HS-100: VGCF: Donna carbomilled = 87: 2: 4: 7 Weighed so that the solid content is equivalent to 50%, and dispersed with a rotation / revolution mixer. , Negative electrode slurry was prepared. The electrolytic solution used was the same as the electrolytic solution used for the positive electrode.

A negative electrode was prepared in the same manner as the positive electrode except that the prepared negative electrode slurry was transferred to the opening of the negative electrode current collector so that the coating mass of the solid content was 35 mg / cm ² .

The positive and negative electrodes produced as described above were opposed to each other and vacuum-sealed with a laminated film to complete a laminated battery (full cell).

The obtained laminated battery was charged and discharged according to the following procedure to obtain cell aging.
(Aging procedure)
・ 10mA constant current, 4.2V end charge, 10mA constant current, 2.5V end discharge for 2 cycles ・ 20mA, 4.2V constant current constant voltage, 2mA end charge, 20mA constant current, 2.5V end discharge・ After 2mA termination charging at a constant current constant voltage of 40mA and 4.2V, the cell after aging is opened with a constant current of 40mA and 2.5V termination discharge, and the cell is degassed by vacuum sealing again to complete the cell. I let you.

After the completed cell was finally charged at 4 mA at a constant current constant voltage of 40 mA and 4.2 V, it was discharged at 10 mA, 20 mA, 33 mA, 50 mA, and 100 mA, respectively, and the discharge rate characteristics were confirmed. Table 12 shows the results including the discharge capacity of the electrode per active material.

As can be seen from the results in Table 12, the discharge capacity is increased (improved) by addition of LiNbO _3. The carbon-coated LiNbO ₃ had a further increased discharge capacity as compared to the carbon-uncoated LiNbO ₃ . Further, the discharge capacity as the average particle diameter of LiNbO ₃ is small increased. The reason for this is that LiNbO ₃ is widely dispersed in the thick film electrode as its average particle size is smaller, and it is presumed that the mobility of Li ions increases.

According to the present invention, a novel inorganic solid oxide or the like can be provided.

Claims (20)

An inorganic solid oxide coated with carbonaceous material. The inorganic solid oxide according to claim 1, which is a sintered body of an inorganic solid oxide and a carbonaceous material. The inorganic solid oxide according to claim 1 or 2, which is conductive. The inorganic solid oxide according to any one of claims 1 to 3, wherein the inorganic solid oxide is a ferroelectric substance. The inorganic solid oxide according to any one of claims 1 to 4, wherein the inorganic solid oxide is an oxide containing at least one metal selected from titanium and niobium. The inorganic solid oxide according to any one of claims 1 to 5, wherein the inorganic solid oxide is a perovskite type oxide. The inorganic solid oxide according to any one of claims 1 to 6, wherein the inorganic solid oxide contains at least one selected from an alkaline earth metal titanate and an alkali metal niobate. The inorganic solid oxide according to any one of claims 1 to 7, wherein the carbonaceous substance contains amorphous carbon and / or graphite. The method for producing an inorganic solid oxide according to any one of claims 1 to 8, wherein the inorganic solid oxide is coated with a carbonaceous substance. The production method according to claim 9, wherein a mixture of an inorganic solid oxide and a carbonaceous material is calcined. A positive electrode mixture containing the inorganic solid oxide according to any one of claims 1 to 8. A positive electrode having a positive electrode active material layer containing the inorganic solid oxide according to any one of claims 1 to 8. The positive electrode according to claim 12, wherein the proportion of the inorganic solid oxide according to any one of claims 1 to 8 is 0.05 to 10% by mass with respect to the entire positive electrode active material layer. The positive electrode according to claim 12 or 13, wherein the ratio of the inorganic solid oxide according to any one of claims 1 to 8 is 0.1 part by mass or more with respect to 100 parts by mass of the positive electrode active material. 12. The ratio of the inorganic solid oxide according to any one of claims 1 to 8 to 100 parts by mass of the conductive auxiliary agent containing the conductive auxiliary agent is 0.1 to 95 parts by mass. The positive electrode according to any one of 1 to 14. The positive electrode according to any one of claims 12 to 15, wherein the coating mass of the positive electrode active material layer is 10 mg / cm ² or more. The positive electrode according to any one of claims 12 to 16, which contains a positive electrode active material capable of storing and releasing lithium ions and is used in a lithium ion secondary battery. A battery comprising the positive electrode according to any one of claims 12 to 17. The battery according to claim 18, which is a lithium ion secondary battery provided with an electrolytic solution containing a lithium salt. 19. The battery of claim 19, wherein the lithium salt comprises at least one selected from LiPF ₆ and lithium bis (fluorosulfonyl) imide.

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