JP2018041686A - Positive electrode for electric device and lithium ion battery using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a positive electrode for electric device having high cycle characteristics and a small voltage drop, and to provide a lithium ion battery using the same.SOLUTION: A positive electrode (10) for electric device includes a positive electrode active material containing a solid-solution lithium-containing transition metal oxide represented by a formula: Li(NiCoMn(Li))O(in the formula, Li indicates lithium, Ni indicates nickel, Co indicates cobalt, Mn indicates manganese, O indicates oxygen, a, b, c and d satisfy following relations, 0<a<1.4, 0≤b<1.4, 0<c<1.4, 0.1<d≤0.4, a+b+c+d=1.5, 1.1≤a+b+c<1.4), a fibrous conductive aid, and a granular conductive aid.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a positive electrode for an electric device and a lithium ion battery using the same. Specifically, the present invention relates to a positive electrode for an electric device having cycle characteristics while suppressing a voltage drop, and a lithium ion battery using the same.

  2. Description of the Related Art In recent years, development of batteries having excellent cycle characteristics that do not deteriorate in performance even when repeatedly charged and discharged as drive power sources for electronic devices and vehicle running has been promoted.

For example, Patent Document 1 discloses a positive electrode for a non-aqueous electrolyte secondary battery in order to realize a high discharge capacity and capacity retention rate. Specifically, Patent Document 1 includes a positive electrode active material and a conductive additive, and the positive electrode active material is represented by a chemical formula: Li _1.5 [Ni _a Co _b Mn _c [Li] _d ] O _3. A positive electrode for a non-aqueous electrolyte secondary battery containing a solid solution lithium-containing transition metal oxide is disclosed. In the formula, Li represents lithium, Ni represents nickel, Co represents cobalt, Mn represents manganese, and O represents oxygen. In the formula, a, b, c and d are 0 <a <1.4, 0 ≦ b <1.4, 0 <c <1.4, 0.1 <d ≦ 0.4, a + b + c + d = The relationship of 1.5, 1.1 ≦ a + b + c <1.4 is satisfied. And the conductive support agent of patent document 1 contains a carbon material, and it discloses that the BET specific surface area of a carbon material is 30-200 m < ² > / g.

International Publication No. 2015/015894

  However, due to market demand, an electric device having higher cycle characteristics is required. In addition, when a positive electrode active material containing a solid solution lithium-containing transition metal oxide is discharged in an electric device, the voltage may drop suddenly at a low potential, so that more stable power supply can be achieved. Therefore, an electric device having a small voltage drop is desired.

  The present invention has been made in view of the problems of such conventional techniques. An object of the present invention is to provide a positive electrode for an electric device having high cycle characteristics and a small voltage drop, and a lithium ion battery using the same.

A positive electrode for an electric device according to an aspect of the present invention includes a positive electrode active material containing a solid solution lithium-containing transition metal oxide represented by the chemical formula: Li _1.5 [Ni _a Co _b Mn _c [Li] _d ] O ₃ And a fibrous conductive aid and a granular conductive aid.

  According to the present invention, it is possible to provide a positive electrode for an electric device having high cycle characteristics and a small voltage drop, and a lithium ion battery using the positive electrode.

FIG. 1 is a cross-sectional view schematically illustrating an example of a lithium ion battery according to the present embodiment. FIG. 2 is a charge / discharge curve showing the difference in voltage drop of the lithium ion batteries in Example 1 and Comparative Example 1.

  Hereinafter, the positive electrode for an electric device and a lithium ion battery using the same according to the present embodiment will be described in detail with reference to the drawings. In addition, the dimension ratio of drawing is exaggerated on account of description, and may differ from an actual ratio.

[Electric Device Positive Electrode 10]
The positive electrode 10 for electric devices of this embodiment is equipped with a positive electrode active material and a conductive support agent. The positive electrode active material contains a solid solution lithium-containing transition metal oxide represented by the chemical formula: Li _1.5 [Ni _a Co _b Mn _c [Li] _d ] O ₃ . In the formula, Li represents lithium, Ni represents nickel, Co represents cobalt, Mn represents manganese, and O represents oxygen. In the formula, a, b, c and d are 0 <a <1.4, 0 ≦ b <1.4, 0 <c <1.4, 0.1 <d ≦ 0.4, a + b + c + d = The relationship of 1.5, 1.1 ≦ a + b + c <1.4 is satisfied. By using such a positive electrode 10 for an electric device, the discharge capacity of the electric device can be increased. Moreover, by using such a positive electrode 10 for an electric device, the charge / discharge potential of the electric device can be increased.

  However, when the charge / discharge potential is high, the conductive auxiliary agent tends to be oxidatively decomposed. In order to improve cycle characteristics, a fibrous conductive auxiliary agent having a stable structure even at a high voltage is used as the conductive auxiliary agent. It was considered to be used. However, the cycle characteristics cannot be sufficiently improved only by using a fibrous conductive aid as the conductive aid, and the voltage drop at a low potential cannot be sufficiently reduced.

  Therefore, the conductive support agent of this embodiment contains a fibrous conductive support agent and a granular conductive support agent. By such a synergistic effect using a plurality of conductive assistants, cycle characteristics can be improved as compared with the case where a fibrous conductive assistant or a granular conductive assistant is used alone. Further, by using such a conductive additive, a voltage drop at a low potential can be reduced. In the following, these components will be described.

(Positive electrode active material)
The positive electrode 10 for electric devices of this embodiment is equipped with a positive electrode active material. The positive electrode active material contains a solid solution lithium-containing transition metal oxide represented by the chemical formula: Li _1.5 [Ni _a Co _b Mn _c [Li] _d ] O ₃ . In the formula, Li represents lithium, Ni represents nickel, Co represents cobalt, Mn represents manganese, and O represents oxygen. In the formula, a, b, c and d are 0 <a <1.4, 0 ≦ b <1.4, 0 <c <1.4, 0.1 <d ≦ 0.4, a + b + c + d = The relationship of 1.5, 1.1 ≦ a + b + c <1.4 is satisfied. By using such a positive electrode 10 for an electric device, the discharge capacity of the electric device can be increased. Moreover, by using such a positive electrode 10 for an electric device, the charge / discharge potential of the electric device can be increased. The composition of each element can be measured by, for example, inductively coupled plasma (ICP) emission spectrometry.

  In the above chemical formula, a, b, c and d are 0 <a <1.35, 0 ≦ b <1.35, 0 <c <1.35, 0.15 <d ≦ 0.35, a + b + c + d = 1 .5, 1.15 ≦ a + b + c <1.35 is preferably satisfied. In the above chemical formula, a, b, c and d are 0 <a <1.3, 0 ≦ b <1.3, 0 <c <1.3, 0.15 <d ≦ 0.35, a + b + c + d = 1.5, 1.2 ≦ a + b + c <1.3 is more preferable. When the positive electrode 10 for electric devices provided with such a positive electrode active material is used, the discharge capacity of the electric device can be improved.

  The average primary particle size of the positive electrode active material is preferably 50 nm to 2000 nm, more preferably 100 to 1000 nm, and further preferably 200 nm to 400 nm. By setting the average primary particle diameter of the positive electrode active material in such a range, the discharge capacity of the electric device can be improved. In addition, the average primary particle diameter of the positive electrode active material can be an average value of the major axis of several to several tens of particles measured using a transmission electron microscope (TEM) or a scanning electron microscope (SEM). .

(Conductive aid)
The positive electrode 10 for an electric device according to this embodiment includes a conductive additive. A conductive support agent contains a fibrous conductive support agent and a granular conductive support agent. That is, the positive electrode 10 for an electrical device of the present embodiment includes a fibrous conductive additive and a granular conductive aid. By such a synergistic effect using a plurality of conductive assistants, cycle characteristics can be improved as compared with the case where a fibrous conductive assistant or a granular conductive assistant is used alone. Moreover, the voltage drop of the electrical device at a low potential can be reduced by using such a conductive additive.

  The fibrous conductive auxiliary means a conductive auxiliary having a fiber-like shape. The fiber shape includes, for example, an elongated shape such as a column shape, and the shape such as a straight line shape or a curved shape is not particularly limited. Further, the fiber shape may be a tube shape having a hollow inside as long as it has a fiber-like shape. In the present embodiment, by using such a fibrous conductive additive, a three-dimensional electronic network is formed, so that the conductivity between the positive electrode active materials can be improved.

  As the fibrous conductive additive, for example, carbon fibers such as carbon nanotubes, carbon nanohorns, carbon nanofibers, carbon nanofilaments, carbon fibrils, and vapor grown carbon fibers can be used.

  The fiber diameter of the fibrous conductive additive is preferably 5 nm or more and 50 nm or less. In addition, the fiber diameter of the fibrous conductive additive is more preferably 7 nm or more and 20 nm or less, and further preferably 8 nm or more and 15 nm or less. By setting the fiber diameter of the fibrous conductive additive in such a range, the voltage drop of the electric device at a low potential can be more effectively suppressed. In addition, the fiber diameter of a fibrous conductive support agent can be made into the average value of several to several dozen fiber diameters measured using a transmission electron microscope (TEM) or a scanning electron microscope (SEM).

  The fiber length of the fibrous conductive additive is preferably 50 nm or more and 50 μm or less, and more preferably 500 nm or more and 20 μm or less. By setting the fiber length of the fibrous conductive additive in such a range, the conductivity between the positive electrode active materials can be improved and the cycle characteristics can be improved. In addition, the fiber length of a fibrous conductive support agent can be made into the average value of several to several dozen fiber length measured using the transmission electron microscope (TEM) or the scanning electron microscope (SEM).

  The aspect ratio of the fibrous conductive additive is preferably 10 or more. By setting the aspect ratio of the fibrous conductive additive in such a range, the conductivity between the positive electrode active materials can be improved, and the cycle characteristics can be improved. Further, the aspect ratio of the fibrous conductive additive is more preferably 10 or more and 1000 or less, and further preferably 20 or more and 1000 or less.

  The fiber diameter of the fibrous conductive assistant is preferably 5 nm to 50 nm, and the aspect ratio of the fibrous conductive assistant is preferably 10 or more. By setting the fiber diameter and aspect ratio of the fibrous conductive additive in such a range, the conductivity between the positive electrode active materials can be improved, and the cycle characteristics can be improved.

The specific surface area of the fibrous conductive additive is preferably ^{10 m} 2 / g or more 300 meters ² / g or less, more preferably less 100 m ² / g or more 250 meters ² / g, more preferably 170m ² / g or more 210 m ² / g or less. By setting the specific surface area of the fibrous conductive additive in such a range, the conductivity between the positive electrode active materials can be improved, and the cycle characteristics can be improved. In addition, the BET specific surface area of a fibrous conductive support agent can be measured by BET method by adsorbing nitrogen gas.

  The granular conductive auxiliary means a conductive auxiliary having a grain-like shape, and the long diameter of the granular conductive auxiliary is smaller than the long diameter of the fibrous conductive auxiliary. The granular form includes, for example, shapes such as a spherical shape, a hemispherical shape, an ellipsoid, a short chain shape, a scale shape, a cylindrical shape, and a polygonal column shape, and may be linear or curved. Moreover, the inside of a granular form may be hollow as long as it has a shape like a grain. By using such a granular conductive additive, the surface of the positive electrode active material is uniformly covered with the granular conductive additive, and the reaction overvoltage at low potential peculiar to the solid solution lithium-containing transition metal oxide can be reduced. It is done. Therefore, it is considered that the voltage drop of the electric device at a low potential can be reduced.

  As the particulate conductive additive, for example, carbon powder such as carbon black or graphite can be used. Examples of carbon black include acetylene black, furnace black, channel black, and thermal black. Examples of graphite include natural graphite and artificial graphite.

  The average primary particle diameter of the granular conductive aid is preferably 45 nm or less. By setting the average primary particle diameter of the granular conductive auxiliary to such a range, the surface of the positive electrode active material is uniformly covered with the granular conductive auxiliary, and thus a voltage drop at a low potential can be effectively suppressed. . The average primary particle size of the granular conductive aid is more preferably from 0.1 nm to 35 nm, and further preferably from 1 nm to 30 nm. Moreover, the average primary particle diameter of the particulate conductive additive may be the average value of the major axis of several to several tens of particles actually measured using a transmission electron microscope (TEM) or a scanning electron microscope (SEM). it can.

The specific surface area of the granular conductive aid is preferably 110 m ² / g or more. By setting the specific surface area of the granular conductive additive in such a range, the contact area between the granular conductive auxiliary and the positive electrode active material can be increased, so that a voltage drop at a low potential can be effectively suppressed. . Incidentally, more preferably the specific surface area of the particulate conductive additive is 150 meters ² / g or more, and still more preferably 170m ² / g or more. Further, it is preferred that the specific surface area of the particulate conductive additive is less than 300 meters ² / g, more preferably at 250 meters ² / g or less, still more preferably not more than 210 m ² / g. In addition, the BET specific surface area of a granular conductive support agent can be measured by a BET method by adsorbing nitrogen gas.

The average primary particle diameter of the granular conductive additive is preferably 45 nm or less, and the specific surface area of the granular conductive auxiliary is preferably 110 m ² / g or more. By setting the average primary particle diameter and specific surface area of the granular conductive aid in such a range, the surface of the positive electrode active material is uniformly covered with the granular conductive aid, and the contact area between the granular conductive aid and the positive electrode active material. Can be increased. Therefore, the voltage drop at a low potential can be more effectively suppressed.

  The ratio of the specific surface area of the fibrous conductive additive to the specific surface area of the granular conductive aid is preferably 0.6 or more and 1.3 or less. That is, the value obtained by dividing the specific surface area of the fibrous conductive assistant by the specific surface area of the granular conductive assistant is preferably 0.6 or more and 1.3 or less. By setting the ratio of the specific surface area in such a range, the cycle characteristics are high, and the voltage drop at a low potential can be reduced. The ratio of the specific surface area of the fibrous conductive additive to the granular conductive aid is more preferably 0.7 or more and 1.3 or less, and further preferably 0.8 or more and 1.2 or less.

  The ratio of the mass of the fibrous conductive additive to the mass of the granular conductive aid is preferably 0.8 or more. That is, the value obtained by dividing the mass of the fibrous conductive assistant by the mass of the granular conductive assistant is preferably 0.8 or more. By setting the mass ratio of the conductive assistant in such a range, cycle characteristics are high, and a voltage drop at a low potential can be reduced. In addition, it is more preferable that ratio of the mass of the fibrous conductive support agent with respect to a granular conductive support agent is 0.9 or more. Moreover, the ratio of the mass of the fibrous conductive additive to the granular conductive aid is preferably 2.5 or less, more preferably 2.2 or less, and even more preferably 2.1 or less. In the case of a full cell using a silicon-containing alloy as a negative electrode active material to be described later, the ratio of the mass of the fibrous conductive auxiliary to the mass of the granular conductive auxiliary is preferably more than 1, more than 1.3. Is more preferable, and it is more preferable that it exceeds 1.7.

  The ratio of the average primary particle size of the positive electrode active material to the average primary particle size of the particulate conductive additive is preferably 5 to 100, more preferably 7 to 90, and even more preferably 9 to 80. . By making the ratio of the average primary particle diameter of the positive electrode active material to the average primary particle diameter of the granular conductive auxiliary in such a range, the contact area between the positive electrode active material and the granular conductive auxiliary agent can be increased. The voltage drop of the electric device at the potential can be suppressed.

  The content of the carbon material contained in the fibrous conductive auxiliary and the granular conductive auxiliary is preferably 80% by mass or more, more preferably 90% by mass, and further preferably 95% by mass or more. . Further, the content of the carbon material contained in the conductive assistant is particularly preferably 98% by mass or more, and most preferably 100% by mass. By making content of the carbon material contained in a conductive support agent into such a range, the electroconductivity between positive electrode active materials can be improved.

(Positive electrode active material layer 11)
The positive electrode 10 for an electric device of the present embodiment can include a positive electrode active material layer 11. The positive electrode active material layer 11 can include the positive electrode active material and the conductive additive of the present embodiment. 1-10 mass% is preferable with respect to the positive electrode active material layer 11 whole, and, as for content of the total conductive support of a fibrous conductive support agent and a granular conductive support agent, 2-6 mass% is more preferable. By setting the total content of the conductive assistant in such a range, the conductivity of the positive electrode active material layer 11 can be improved.

  0.1 mass%-5 mass% are preferable with respect to the positive electrode active material layer 11 whole, and, as for content of a fibrous conductive support agent, 1 mass%-3 mass% are more preferable. Moreover, 0.1 mass%-5 mass% are preferable with respect to the whole positive electrode active material layer 11, and, as for content of a granular conductive support agent, 1 mass%-3 mass% are more preferable. By making content of a fibrous conductive support agent and granular conductive support agent into such a range, the cycling characteristics of an electrical device can be made high and the voltage drop in low potential can be made small.

  The positive electrode active material layer 11 can also include a binder or the like, if necessary, in addition to the positive electrode active material and the conductive additive. Examples of the binder material used for the positive electrode active material layer 11 include polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polymethyl acrylate (PMA), polymethyl methacrylate (PMMA), polyether nitrile ( PEN), polyacrylonitrile (PAN), polyimide (PI), polyamide (PA), polyamideimide (PAI), carboxymethylcellulose (CMC), ethylene-vinyl acetate copolymer (EVA), polyvinyl chloride (PVC), polyfluoride Thermoplastic resins such as vinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and polyvinyl fluoride (PVF), thermosetting resins such as epoxy resins, styrene-butadiene rubber (SBR), isoprene rubber (IR), Elastomers such as diene rubber (BR) and the like. These binders may be used independently and may use 2 or more types together. Among these, at least one selected from the group consisting of polyimide (PI), polyamide (PA), and polyamideimide (PAI) is preferable because of excellent adhesion and heat resistance as a binder. Although content of the binder contained in the positive electrode active material layer 11 is not specifically limited, 0.5-15 mass% is preferable with respect to 100 mass% positive electrode active material layer 11, and 1-10 mass% is more. preferable.

(Positive electrode current collector 12)
The positive electrode 10 for an electric device of the present embodiment can include a positive electrode current collector 12 and a positive electrode active material layer 11 disposed on at least one surface of the positive electrode current collector 12. The positive electrode current collector 12 can be arranged so that electrons can be transferred between the positive electrode active material layer 11 and a positive electrode tab 31 described later. The material forming the positive electrode current collector 12 is preferably a metal such as aluminum (Al), titanium (Ti), nickel (Ni), and stainless steel (SUS). Among these, it is preferable to use aluminum (Al) as a material for forming the positive electrode current collector 12.

As described above, the positive electrode 10 for an electric device according to this embodiment includes a positive electrode active material and a conductive additive. The positive electrode active material contains a solid solution lithium-containing transition metal oxide represented by the chemical formula: Li _1.5 [Ni _a Co _b Mn _c [Li] _d ] O ₃ . In the formula, Li represents lithium, Ni represents nickel, Co represents cobalt, Mn represents manganese, and O represents oxygen. In the formula, a, b, c and d are 0 <a <1.4, 0 ≦ b <1.4, 0 <c <1.4, 0.1 <d ≦ 0.4, a + b + c + d = The relationship of 1.5, 1.1 ≦ a + b + c <1.4 is satisfied. And a conductive support agent contains a fibrous conductive support agent and a granular conductive support agent. Therefore, the positive electrode 10 for an electric device according to the present embodiment can improve the cycle characteristics of the electric device and reduce the voltage drop.

[Electrical devices]
The electrical device of the present embodiment can include the electrical device as described above. Therefore, the electrical device of this embodiment can have high cycle characteristics and a small voltage drop. As an electrical device, the lithium ion battery 20 mentioned later, an electric double layer capacitor, etc. are mentioned, for example.

[Lithium ion battery 20]
The electric device of this embodiment can be a lithium ion battery 20. Specifically, the lithium ion battery 20 of the present embodiment can include the positive electrode 10 for electric devices. Therefore, the lithium ion battery 20 of the present embodiment can have high cycle characteristics and a small voltage drop. In addition to the positive electrode 10 for an electric device, the lithium ion battery 20 includes a negative electrode 23 for an electric device, an electrolyte layer 27, a positive electrode tab 31, a negative electrode tab 33, an outer package 35, and the like as necessary, as shown in FIG. Can further be provided. That is, the lithium ion battery 20 can include the exterior body 35 and the battery element 40 accommodated in the exterior body 35. The battery element 40 can be formed by stacking a plurality of single battery layers 37. The unit cell layer 37 can include the positive electrode 10 for electric devices, the negative electrode 23 for electric devices, and the electrolyte layer 27 disposed between the positive electrode 10 for electric devices and the negative electrode 23 for electric devices. In addition, as shown in FIG. 1, a plurality of unit cell layers 37 can be stacked and electrically arranged in parallel.

  As shown in FIG. 1, the positive electrode 10 for an electrical device of the present embodiment includes a positive electrode current collector 12 and a positive electrode active material layer 11 disposed on at least one surface of the positive electrode current collector 12. it can. The negative electrode 23 for an electric device can include a negative electrode current collector 24 and a negative electrode active material layer 25 disposed on at least one surface of the negative electrode current collector 24. Further, the positive electrode tab 31 and the negative electrode tab 33 can take out the current generated in the single battery layer 37 to the outside of the lithium ion battery 20.

  Note that the lithium ion battery 20 of the present embodiment is not limited to the form as shown in FIG. 1. For example, the negative electrode active material layer 25 is disposed on one surface of the current collector, and the other surface of the current collector. Alternatively, a bipolar battery including a bipolar electrode in which the positive electrode active material layer 11 is disposed may be used. Further, the structure of the lithium ion battery 20 is not limited to the stacked type, and may be a wound type lithium ion battery.

(Negative electrode 23 for electrical devices)
The negative electrode 23 for an electric device can include a negative electrode current collector 24 and a negative electrode active material layer 25 disposed on at least one surface of the negative electrode current collector 24.

(Negative electrode current collector 24)
The lithium ion battery 20 of this embodiment can include a negative electrode active material layer 25 disposed on at least one surface of the negative electrode current collector 24. The negative electrode current collector 24 can be arranged so that electrons can be transferred between the negative electrode active material layer 25 and a negative electrode tab 33 described later. The material forming the negative electrode current collector 24 is preferably a metal such as copper (Cu), titanium (Ti), nickel (Ni), stainless steel (SUS). Among these, it is preferable to use copper (Cu) as a material for forming the negative electrode current collector 24.

(Negative electrode active material layer 25)
The negative electrode active material layer 25 can include, for example, a negative electrode active material, a conductive additive, a binder, and the like.

The negative electrode active material can be a material capable of occluding and releasing lithium. As the negative electrode active material, graphite (natural graphite, artificial graphite, etc.) that is highly crystalline carbon, low crystalline carbon (soft carbon, hard carbon), carbon black (Ketjen black, acetylene black, channel black, lamp black, Oil furnace black, thermal black, etc.), fullerenes, carbon nanotubes, carbon nanofibers, carbon nanohorns, carbon fibrils and the like. In addition, the said carbon material contains what contains 10 mass% or less silicon nanoparticles. Further, as the negative electrode active material, silicon (Si), germanium (Ge), tin (Sn), lead (Pb), aluminum (Al), indium (In), zinc (Zn), hydrogen (H), calcium ( Ca), strontium (Sr), barium (Ba), ruthenium (Ru), rhodium (Rh), iridium (Ir), palladium (Pd), platinum (Pt), silver (Ag), gold (Au), cadmium ( Cd), mercury (Hg), gallium (Ga), thallium (Tl), carbon (C), nitrogen (N), antimony (Sb), bismuth (Bi), oxygen (O), sulfur (S), selenium ( Se), tellurium (Te), elemental elements alloyed with lithium, such as chlorine (Cl), and oxides containing these elements (silicon monoxide (SiO), SiO _x (0 <x <2), dioxide dioxide) Tin (S _{O 2), SnO x (0} <x <2), etc. SnSiO ₃₎ and the like carbides (silicon carbide (SiC)), and the like. Further, examples of the negative electrode active material include metal materials such as lithium metal and lithium-transition metal composite oxides such as lithium-titanium composite oxide (lithium titanate: Li ₄ Ti ₅ O ₁₂ ). These negative electrode active materials may be used alone or in combination of two or more.

  The negative electrode active material preferably contains a silicon-containing alloy having a silicon content of 20% by mass or more. Since the silicon-containing alloy is alloyed with lithium ions during charging, the discharge capacity per mass of the negative electrode active material can be increased. Further, when the silicon content of the silicon-containing alloy is 20% by mass or more, the amorphous-crystal phase transition can be suppressed. Therefore, the cycle characteristics of the lithium ion battery 20 can be improved.

  In the present embodiment, the silicon-containing alloy includes Si, Sn, and M elements, and M is at least one element selected from the group consisting of transition elements, B, C, Mg, Al, and Zn. preferable. The transition element refers to an element between the Group 3 element and the Group 11 element. In addition, the silicon-containing alloy includes a parent phase mainly composed of amorphous or low crystalline silicon, and a silicide phase including a transition metal silicide dispersed in the parent phase mainly composed of silicon. It is preferable to include. By using the silicon-containing alloy in this way, it is possible to provide the lithium ion battery 20 having excellent cycle characteristics and a large discharge capacity.

  M is at least one element selected from the group consisting of B, C, Mg, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, and Ta. More preferably. M is more preferably at least one element selected from the group consisting of C, Al, Ti, V, and Zn. Furthermore, it is most preferable that it is at least any one of Al or Ti. When a silicon-containing alloy containing such an element is used for the lithium ion battery 20, the cycle characteristics can be further improved while maintaining the discharge capacity.

  The silicon-containing alloy containing Si, Sn, and M elements may contain inevitable impurities. An inevitable impurity means what exists in a raw material or is inevitably mixed in a manufacturing process. Inevitable impurities are essentially unnecessary impurities, but they are a very small amount and do not affect the characteristics of the silicon-containing alloy, so that they are acceptable impurities. The content of inevitable impurities is preferably less than 0.5% by mass relative to the entire silicon-containing alloy, more preferably less than 0.1% by mass, and further preferably less than 0.01% by mass. preferable.

  The general formula of the silicon-containing alloy is preferably Si—Sn—M, and more preferably Si—Sn—Ti or Si—Sn—Ti—Al. Here, in the general formula Si-Sn-Ti, the Sn content is 7% by mass or more and 30% by mass or less, the Ti content is more than 0% by mass and 37% by mass or less, and the balance is Si and inevitable impurities. preferable. Or in general formula Si-Sn-Ti, it is preferable that Sn content is 30 mass% or more and 51 mass% or less, Ti content exceeds 0 mass% and 35 mass% or less, and the remainder is Si and inevitable impurities. . In the general formula Si-Sn-Ti, it is more preferable that the Sn content is 7% by mass or more and 30% by mass or less, Ti is more than 7% by mass and 37% by mass or less, and the balance is Si and inevitable impurities. Alternatively, it is more preferable that the Sn content is 30% by mass or more and 51% by mass or less, the Ti content is more than 7% by mass and 35% by mass or less, and the balance is Si and inevitable impurities. Further, in the general formula Si—Sn—Ti, the Sn content is 7% by mass to 30% by mass, the Ti content is 18% by mass to 37% by mass, and the balance is Si and inevitable impurities. preferable. Or, in the general formula Si-Sn-Ti, the Sn content is 30% by mass or more and 51% by mass or less, the Ti content is more than 7% by mass and 20% by mass or less, and the balance is Si and inevitable impurities. preferable. Furthermore, in the general formula Si—Sn—Ti, the Sn content is 7% by mass or more and 21% by mass or less, the Ti content is 24% by mass or more and 37% by mass or less, and the remainder is Si and inevitable impurities. preferable. By setting the content of each element within the above range, the lithium ion battery 20 having excellent cycle characteristics can be provided.

  In the general formula Si-Sn-Ti-Al, the Sn content is 2 mass% to 10 mass%, the Ti content is 25 mass% to 35 mass%, and the Al content is 0.3 mass%. It is preferable that the content is 3% by mass or less and the balance is Si and inevitable impurities. By setting the content of each element within the above range, the lithium ion battery 20 having excellent cycle characteristics can be provided.

  Examples of the material for forming the conductive additive used for the negative electrode active material layer 25 include carbon black such as acetylene black, and carbon materials such as graphite and carbon fiber. These conductive assistants may be used alone or in combination of two or more. By including a conductive additive in the negative electrode active material layer 25, an electronic network inside the negative electrode active material layer 25 is effectively formed, and the discharge capacity of the lithium ion battery 20 can be improved. 1-10 mass% is preferable with respect to the whole negative electrode active material layer 25, and, as for content of a conductive support agent, 2-6 mass% is more preferable. By making content of a conductive support agent into such a range, the electroconductivity of the negative electrode active material layer 25 can be improved.

  In addition to the silicon-containing alloy, the negative electrode active material layer 25 can further contain a binder depending on the application. As the binder used for the negative electrode active material layer 25, the same binder as that used for the positive electrode active material layer 11 can be used. Further, the content of the binder contained in the negative electrode active material layer 25 can be the same as the content of the binder used in the positive electrode active material layer 11.

(Electrolyte layer 27)
The lithium ion battery 20 of the present embodiment can further include an electrolyte layer 27 disposed between the positive electrode 10 for electric devices and the negative electrode 23 for electric devices. The electrolyte layer 27 isolates the electric device negative electrode 23 and the electric device positive electrode 10 and mediates the movement of lithium ions. The thickness of the electrolyte layer 27 is preferably 1 to 100 μm, and more preferably 5 to 50 μm, from the viewpoint of reducing internal resistance. The electrolyte layer 27 includes a nonaqueous electrolyte. As the non-aqueous electrolyte, a gel or solid polymer electrolyte in which a lithium salt is dissolved in an ion conductive polymer, and a liquid electrolyte in which a lithium salt is dissolved in an organic solvent can be used.

  Examples of the ion conductive polymer used in the polymer electrolyte include polyethylene oxide (PEO), polypropylene oxide (PPO), polyvinylidene fluoride (PVDF), hexafluoropropylene, polyethylene glycol (PEG), polyacrylonitrile (PAN), and polymethyl. Examples include methacrylate (PMMA) and copolymers thereof.

Examples of the organic solvent used in the liquid electrolyte include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylene carbonate (VC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl. And carbonates such as carbonate (EMC) and methylpropyl carbonate (MPC). As the lithium salt used in the liquid _{electrolyte, Li (CF 3 SO 2)} 2 N, Li (C 2 F 5 SO 2) 2 N, LiPF 6, LiBF 4, LiAsF 6, LiTaF 6, LiClO 4, LiCF ₃ SO ₃ etc. are mentioned.

(Positive electrode tab 31 and negative electrode tab 33)
The lithium ion battery 20 can further include a positive electrode tab 31 that electrically connects the positive electrode current collector 12 and a device outside the lithium ion battery 20. The lithium ion battery 20 can further include a negative electrode tab 33 that electrically connects the negative electrode current collector 24 and a device outside the lithium ion battery 20. The material which forms the positive electrode tab 31 and the negative electrode tab 33 is not specifically limited, For example, at least 1 selected from the group which consists of aluminum, copper, titanium, nickel can be used. In addition, the material which forms the positive electrode tab 31 and the negative electrode tab 33 may be the same, or may differ.

(Exterior body 35)
The lithium ion battery 20 of the present embodiment can further include an exterior body 35 that houses the battery element 40. As the exterior body 35, for example, a can or one formed of a film can be used. The shape of the exterior body 35 is not particularly limited, and can be a cylindrical shape, a square shape, or a sheet shape. Although not particularly limited, it is preferable that the exterior body 35 is formed of a film from the viewpoint of reduction in size and weight. Among these, from the viewpoint of high output and cooling performance, the film is preferably a laminate film, and the laminate film preferably contains aluminum. The lithium ion battery 20 is preferably a flat stacked lithium ion battery. Since such a lithium ion battery 20 can increase the discharge capacity and the heat dissipation performance, it is optimal for mounting in a vehicle. As an example of the laminate film containing aluminum, there is a three-layer laminate film of PP / aluminum / nylon.

  Although the use of the lithium ion battery 20 of the present embodiment is not particularly limited, as described above, the voltage drop is improved while maintaining a high discharge capacity. Therefore, it can be suitably used for vehicles. Specifically, the lithium ion battery 20 of the present embodiment can be suitably used for a drive power source for vehicles.

  Hereinafter, the present embodiment will be described in more detail with reference to Examples and Comparative Examples, but the present embodiment is not limited to these.

[Example 1]
(Preparation of positive electrode)
A 2 mol / L aqueous solution of nickel acetate, cobalt acetate and manganese acetate was prepared. Next, a predetermined amount was weighed so that the composition would be Li _1.5 [Ni _0.281 Co _0.281 Mn _0.688 [Li _0.25 ]] O ₃ to prepare a mixed solution. Then, while stirring the mixed solution with a magnetic stirrer, ammonia water was added dropwise to the mixed solution until the pH reached 7. Further, a 2 mol / L aqueous sodium carbonate solution was dropped into the mixed solution to precipitate a nickel-cobalt-manganese composite carbonate. The obtained precipitate was subjected to suction filtration, washed with water, and dried under conditions of about 120 ° C. and about 5 hours. And the obtained dried material was calcined under conditions of about 500 ° C. and about 5 hours. Lithium hydroxide was added to this so that the composition would be Li _1.5 [Ni _0.281 Co _0.281 Mn _0.688 [Li _0.25 ]] O _3, and kneaded for about 30 minutes in an automatic mortar. Furthermore, it heated at the temperature increase rate of 50 degreeC / hour in air | atmosphere, and after that, this baking was performed for about 12 hours at 750 degreeC, and the positive electrode active material was obtained.

To 94.5 parts by mass of the positive electrode active material thus obtained, 3.0 parts by mass of a conductive additive and 30 parts by mass of a solvent are added, and a planetary mixer (Primics Co., Ltd., Hibismix 2P-03 type) is added. Kneaded to prepare a conductive auxiliary agent solution. In addition, the conductive auxiliary agent used 1.5 mass parts of fibrous conductive auxiliary agents A, and 1.5 mass parts of granular conductive auxiliary agents A. The solvent used was N-methylpyrrolidone (NMP). Moreover, the fiber diameter of the fibrous conductive support agent A was 11 nm, and the specific surface area was 200 m < ² > / g. The average primary particle diameter of the granular conductive additive A was 25 nm, and the specific surface area was 206 m ² / g.

  A binder solution prepared by dissolving 2.5 parts by mass of a binder with 45.0 parts by mass of a solvent was added to the conductive auxiliary agent solution thus obtained, and the mixture was kneaded again with a planetary mixer to prepare a positive electrode slurry. Note that N-methylpyrrolidone (NMP) was used as the solvent. Moreover, the solid content concentration of the produced positive electrode slurry was 57.1% by mass.

The positive electrode slurry thus obtained was applied to one surface of the positive electrode current collector with a bar coater so that the thickness of the positive electrode active material layer after drying was 50 μm. Next, the positive electrode current collector coated with the positive electrode slurry was placed on a hot plate and dried at 120 ° C. to 130 ° C. for 10 minutes so that the residual amount of the solvent was 0.02% by mass or less. The product obtained by drying in this way is compression-molded with a roller press, and the mass of the positive electrode active material layer is about 3.5 mg / cm ² , the film thickness is about 50 μm, and the density is 2.70 g / cm ^3. Was cut as follows. As the positive electrode current collector, an aluminum foil having a thickness of 20 μm was used.

Next, the obtained cut product was placed in a vacuum dryer and decompressed (100 mmHg (1.33 × 10 ⁴ Pa)) at room temperature (25 ° C.). Subsequently, the temperature was increased to 120 ° C. at a temperature increase rate of 10 ° C./min while flowing nitrogen gas at 100 cm ³ / min. Then, after hold | maintaining for 12 hours in the state pressure-reduced to 100 mmHg (1.33 * 10 < ⁴ > Pa) at 120 degreeC, it was made to cool to room temperature (25 degreeC). The dried product thus obtained was used as the positive electrode.

(Production of lithium ion battery)
In a glove box in an argon gas atmosphere, the positive electrode obtained as described above and the negative electrode of metallic lithium were punched into a circle having a diameter of 15 mm and faced each other, and an electrolyte layer was disposed therebetween. Two electrolyte layers having a thickness of 20 μm made of polypropylene were used. In addition, the positive electrode and the negative electrode used what was dried at 100 degreeC with the vacuum dryer for 2 hours before lithium ion battery preparation.

  Next, the laminate of the negative electrode, the electrolyte layer, and the positive electrode was disposed on the bottom side of a coin cell (CR2032) made of stainless steel (SUS316). Further, a gasket for maintaining insulation between the positive electrode and the negative electrode was attached, and 150 μl of the electrolyte solution was injected with a syringe. And a spring and a spacer were laminated | stacked, the upper part side of the coin cell was piled up, and it sealed by crimping, and produced the lithium ion battery. In addition, the member used for an electrolyte layer or a coin cell is previously dried at room temperature for 24 hours or more in a glove box in an argon gas atmosphere.

In addition, the following was used as electrolyte solution. First, an organic solvent in which ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed at a volume ratio of EC: DEC = 1: 2 was prepared. To this, lithium hexafluorophosphate (LiPF ₆ ) as a supporting salt was dissolved so as to have a concentration of 1 mol / L to obtain an electrolytic solution.

(Activation process)
The coin cell obtained as described above was charged at a constant current of 0.1 C at room temperature (25 ° C.) until the maximum voltage reached 4.8 V, and then 0 until the minimum battery voltage reached 2.0 V. A charge / discharge cycle for constant current discharge at 1 C was performed for only one cycle to obtain a lithium ion battery.

[Example 2]
A lithium ion battery was produced in the same manner as in Example 1 except that the addition amount of the fibrous conductive additive A was 2.0 parts by mass and the addition amount of the granular conductive additive A was 1.0 parts by mass.

[Example 3]
A lithium ion battery was produced in the same manner as in Example 1, except that 1.5 parts by mass of the fibrous conductive additive B and 1.5 parts by mass of the granular conductive additive B were used as the positive electrode conductive additive. The fibrous conductive additive B had a fiber diameter of 10 nm and a specific surface area of 180 m ² / g. The average primary particle diameter of the granular conductive additive B was 26 nm, and the specific surface area was 150 m ² / g.

[Example 4]
A lithium ion battery was produced in the same manner as in Example 1 except that 1.5 parts by mass of the fibrous conductive additive B and 1.5 parts by mass of the granular conductive additive A were used as the positive electrode conductive additive.

[Comparative Example 1]
A lithium ion battery was produced in the same manner as in Example 1 except that 1.5 parts by mass of the fibrous conductive additive A and 1.5 parts by mass of the fibrous conductive additive B were used as the positive electrode conductive additive. .

[Comparative Example 2]
A lithium ion battery was produced in the same manner as in Example 1 except that only 3.0 parts by mass of the fibrous conductive additive A was used as the positive electrode conductive additive.

[Comparative Example 3]
A lithium ion battery was produced in the same manner as in Example 1 except that only 3.0 parts by mass of the fibrous conductive additive B was used as the positive electrode conductive additive.

[Comparative Example 4]
A lithium ion battery was produced in the same manner as in Example 1 except that only 3.0 parts by mass of the fibrous conductive additive C was used as the positive electrode conductive additive. The fibrous conductive additive C had a fiber diameter of 150 nm and a specific surface area of 7.7 m ² / g.

[Comparative Example 5]
A lithium ion battery was produced in the same manner as in Example 1 except that only 3.0 parts by mass of the particulate conductive additive A was used as the positive electrode conductive additive.

[Comparative Example 6]
A lithium ion battery was produced in the same manner as in Example 1 except that only 3.0 parts by mass of the particulate conductive additive B was used as the positive electrode conductive additive.

[Comparative Example 7]
A lithium ion battery was produced in the same manner as in Example 1 except that only 3.0 parts by mass of the particulate conductive additive C was used as the positive electrode conductive additive. In addition, the average primary particle diameter of the granular conductive additive C was 47 nm, and the specific surface area was 108 m ² / g.

[Evaluation]
About the half cell lithium ion battery of an Example and a comparative example, discharge capacity, a voltage drop, and the discharge capacity maintenance factor of the 100th cycle were evaluated. The results are shown in Table 1.

(Discharge capacity)
At room temperature (25 ° C.), after charging at a constant current of 0.1 C until the maximum voltage becomes 4.6 V, a charge / discharge cycle in which the constant current is discharged at 0.1 C until the minimum voltage becomes 2.0 V is 5 Cycled. In the fifth cycle, the electric capacity when discharging from 4.6 V to 2.0 V was defined as the discharge capacity.

(Voltage drop)
After charging at a constant current of 0.2 C until the maximum voltage reached 4.6 V, one charge / discharge cycle was performed at a constant current discharge at 0.1 C until the minimum voltage reached 2.0 V. Then, in the first cycle, the difference between the voltage when the discharge capacity of the lithium ion battery reached 200 mAh / g and 3.20 V was calculated and used as the voltage drop value. The value of 3.20 V is the voltage when the discharge capacity becomes 200 mAh / g without any voltage drop from the slope of the discharge curve when the discharge capacity becomes 80 mAh / g in the first cycle. It is what guessed. For reference, the charge / discharge curves of Example 1 and Comparative Example 1 are shown in FIG.

(Discharge capacity maintenance rate at 100th cycle)
At room temperature (25 ° C.), after charging at a constant current of 0.1 C until the maximum voltage is 4.6 V, a charge / discharge cycle is performed at a constant current of 1.0 C until the minimum voltage is 2.0 V. Cycled. Then, in the first cycle and the 100th cycle, the discharge capacity when discharging from 4.6 V to 2.0 V was measured, and the ratio of the discharge capacity of the first cycle to the discharge capacity of the 100th cycle was determined as the discharge of the 100th cycle. The capacity maintenance rate was used.

  While the positive electrodes of Comparative Examples 1 to 7 do not contain either a fibrous conductive additive or a granular conductive aid, the positive electrodes of Examples 1 to 4 have a fibrous conductive aid and a granular conductive aid. including. Therefore, the lithium ion battery using the positive electrode for electric devices of Examples 1 to 4 has a smaller voltage drop and a discharge capacity maintenance rate than the lithium ion battery using the positive electrode for electric devices of Comparative Examples 1 to 7. It turns out that becomes large.

  Next, in place of the half cell using lithium metal as the negative electrode, it was confirmed whether the cycle characteristics were deteriorated even in a full cell using a silicon-containing alloy as the negative electrode. The full-cell evaluation was performed because the silicon-containing alloy has a higher resolution of the electrolytic solution than graphite and the like, and there is a possibility that the movable lithium ions in the electrolytic solution are reduced. In addition, it is considered that a side reaction product such as an alkyl carbonate produced due to the silicon-containing alloy may move to the positive electrode side and inhibit the reaction at the positive electrode.

[Example 5]
A lithium ion battery was produced in the same manner as in Example 1 except that instead of metallic lithium, a silicon-containing alloy produced as follows was used as the negative electrode active material.

(Preparation of negative electrode)
First, metal powders were alloyed by a mechanical alloy method using a planetary ball mill (P-6, manufactured by Friitch Germany). Specifically, a metal powder prepared so as to have a mass ratio of Si: Sn: Ti = 60: 10: 30 and pulverized balls made of zirconia were put into a container made of zirconia. Then, the base which fixes the container made from zirconia was rotated at 600 rpm for 12.5 hours, and metal powder was alloyed.

  80 parts by mass of the negative electrode active material thus obtained, 5 parts by mass of a conductive additive, and 15 parts by mass of a binder are dispersed in 100 parts by mass of N-methylpyrrolidone, and a defoaming kneader (AR manufactured by Thinky Co., Ltd.). -100) to obtain a negative electrode slurry. In addition, acetylene black was used for the conductive assistant, and polyimide was used for the binder.

  Next, a negative electrode slurry is uniformly applied on one surface of the negative electrode current collector so that the thickness of the negative electrode active material layer after drying is 30 μm, and dried in a vacuum for 24 hours. Obtained. The negative electrode current collector was a 10 μm thick copper foil.

[Example 6]
A lithium ion battery was produced in the same manner as in Example 2 except that the silicon-containing alloy used in Example 5 was used instead of metallic lithium.

[Example 7]
A lithium ion battery was produced in the same manner as in Example 4 except that the silicon-containing alloy used in Example 5 was used instead of metallic lithium.

[Comparative Example 8]
A lithium ion battery was produced in the same manner as in Comparative Example 2, except that the silicon-containing alloy used in Example 5 was used instead of metallic lithium.

[Comparative Example 9]
A lithium ion battery was produced in the same manner as in Comparative Example 3, except that the silicon-containing alloy used in Example 5 was used instead of metallic lithium.

[Comparative Example 10]
A lithium ion battery was produced in the same manner as in Comparative Example 5 except that the silicon-containing alloy used in Example 5 was used instead of metallic lithium.

[Comparative Example 11]
A lithium ion battery was produced in the same manner as in Comparative Example 6, except that the silicon-containing alloy used in Example 5 was used instead of metallic lithium.

[Comparative Example 12]
A lithium ion battery was produced in the same manner as in Comparative Example 7, except that the silicon-containing alloy used in Example 5 was used instead of metallic lithium.

[Evaluation]
With respect to the full-cell lithium ion batteries using the silicon-containing alloys of Examples and Comparative Examples, the discharge capacity maintenance rate and the Coulomb efficiency at the 50th cycle were evaluated. The results are shown in Table 2.

(Discharge capacity maintenance rate at 50th cycle)
The discharge capacity retention rate at the 50th cycle was measured as follows. A charge / discharge cycle in which constant current charging is performed at 0.1 C until the maximum voltage becomes 4.6 V at room temperature (25 ° C.), and then constant current discharge is performed at 1.0 C until the minimum voltage becomes 2.0 V. Cycled. Then, in the first cycle and the 50th cycle, the discharge capacity when discharging from 4.6 V to 2.0 V was measured, and the ratio of the first cycle discharge capacity to the 50th cycle discharge capacity was determined as the 50th cycle discharge. The capacity maintenance rate was used.

(Coulomb efficiency)
Coulomb efficiency was measured as follows. A charge / discharge cycle in which constant current charging is performed at 0.1 C until the maximum voltage becomes 4.6 V at room temperature (25 ° C.), and then constant current discharge is performed at 1.0 C until the minimum voltage becomes 2.0 V. Cycled. And the average value of the ratio of the discharge capacity with respect to the charge capacity in each cycle was made into coulomb efficiency. The charge capacity was the electric capacity when charging from 2.0 V to 4.6 V, and the discharge capacity was the electric capacity when discharging from 4.6 V to 2.0 V.

  From the results of Table 2, even when a silicon-containing alloy was used for the negative electrode, Examples 5 to 7 containing the fibrous conductive additive and the granular conductive additive in the positive electrode were The discharge capacity maintenance rate and the Coulomb efficiency were superior to Comparative Examples 8 to 12 in which either one was not included. Specifically, in the lithium ion batteries of Examples 5 to 7, the discharge capacity maintenance rate at the 50th cycle was 80% or more, and the coulomb efficiency was 99.36% or more. On the other hand, in the lithium ion batteries of Comparative Examples 8 to 12, the discharge capacity maintenance rate at the 50th cycle was 75% or less, and the Coulomb efficiency was 99.34% or less. Therefore, it was found that even when a silicon-containing alloy was used for the negative electrode, the cycle characteristics of the positive electrode containing the fibrous conductive auxiliary and the granular conductive auxiliary did not deteriorate.

  Further, according to comparison between Example 5 and Example 6, in the full cell, when the content of the fibrous conductive additive is larger than the content of the granular conductive additive, the discharge capacity maintenance ratio and the Coulomb efficiency at the 50th cycle are It turns out that it improves.

  Although the present invention has been described with reference to the examples and comparative examples, the present invention is not limited to these, and various modifications can be made within the scope of the gist of the present invention.

10 Positive electrode for electric device 20 Lithium ion battery

Claims (6)

Chemical formula:
_{Li 1.5 [Ni a Co b Mn} c [Li] d] O 3
(In the formula, Li represents lithium, Ni represents nickel, Co represents cobalt, Mn represents manganese, O represents oxygen, and a, b, c and d are 0 <a <1.4 and 0 ≦ b <1.4. , 0 <c <1.4, 0.1 <d ≦ 0.4, a + b + c + d = 1.5, 1.1 ≦ a + b + c <1.4) A positive electrode active material containing the product,
A fibrous conductive aid;
A granular conductive aid;
A positive electrode for an electric device.   2. The positive electrode for an electrical device according to claim 1, wherein the fibrous conductive additive has a fiber diameter of 5 nm to 50 nm, and the fibrous conductive additive has an aspect ratio of 10 or more. 3. The positive electrode for an electric device according to claim 1, wherein an average primary particle diameter of the granular conductive additive is 45 nm or less, and a specific surface area of the granular conductive auxiliary is 110 m ² / g or more.   The ratio of the mass of the said fibrous conductive support agent with respect to the mass of the said granular conductive support agent is 0.8 or more, The positive electrode for electrical devices of any one of Claims 1-3 characterized by the above-mentioned.   The ratio of the specific surface area of the said fibrous conductive support agent with respect to the specific surface area of the said granular conductive support agent is 0.6 or more and 1.3 or less, The electricity of any one of Claims 1-4 characterized by the above-mentioned. Positive electrode for devices.   The lithium ion battery provided with the positive electrode for electrical devices of any one of Claims 1-5.

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