JP2014146431A - Positive electrode material for electric power storage devices - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a positive electrode material for electric power storage devices excellent in rapid charge and discharge performance.SOLUTION: A positive electrode material for electric power storage devices comprises: a positive electrode active material including crystallized glass having, as its main crystal, precipitates of olivine crystals expressed by the general formula, LiMFePO(0≤x<1; and M is at least one kind selected from a group consisting of Nb, Ti, V, Cr, Mn, Co and Ni); and a conductive assistant including conductive carbon black having a volume density of 140-300 kg/m.

Description

  The present invention relates to a positive electrode material (hereinafter simply referred to as “positive electrode material”) for an electricity storage device such as a lithium ion non-aqueous secondary battery used for portable electronic devices, electric vehicles, and the like.

Power storage devices, especially lithium ion secondary batteries, have established themselves as high-capacity and lightweight power supplies that are indispensable for portable electronic terminals and electric vehicles. Conventionally, a metal oxide crystal such as lithium cobaltate (LiCoO ₂ ) or lithium manganate (LiMn ₂ O ₄ ) has been used as a positive electrode active material of a lithium ion secondary battery, and a nano-sized conductive material has been used as a conductive assistant. Carbon and the like have been used. However, with the recent increase in power consumption due to higher performance of electronic devices, further increase in capacity of lithium ion secondary batteries is required. In addition, from the viewpoint of environmental conservation problems and energy problems, there is a demand for conversion from a positive electrode active material having a large environmental load such as Co or Mn to a more environmentally conscious positive electrode active material. Furthermore, since the problem of depletion of cobalt resources has attracted attention and the price tends to rise, it is desired to switch to a cheaper cathode active material.

In recent years, since it is advantageous in terms of cost and resources, among the lithium compounds containing iron, the general formula LiM _x Fe _1-x PO ₄ (0 ≦ x ≦ 1, M is Nb, Ti, V, Cr, An olivine-type crystal represented by at least one selected from Mn, Co, and Ni has attracted attention as one of the positive electrode active materials, and various researches and developments have been advanced (for example, see Patent Document 1). The positive electrode active material made of LiM _x Fe _1-x PO ₄ crystal has excellent temperature stability and safe operation at high temperature compared to the positive electrode active material made of metal oxide crystal such as LiCoO ₂ or LiMn ₂ O _4. Be expected. Moreover, since it is a structure which has phosphoric acid as a skeleton, it has the characteristic that it is excellent in the tolerance to structural deterioration by charging / discharging reaction.

However, since the positive electrode active material made of LiM _x Fe _1-x PO ₄ crystal has much higher internal resistance than the positive electrode active material made of metal oxide crystal such as LiCoO ₂ or LiMn ₂ O ₄ , When this is done, there is a problem that resistance polarization increases and it is difficult to obtain a sufficient discharge capacity.

As a method of solving such a problem, by finely pulverizing a positive electrode active material made of LiM _x Fe _1-x PO ₄ crystal to nano size, the specific surface area is increased to facilitate the diffusion of lithium ions, A method for reducing the internal resistance by shortening the diffusion distance has been proposed (see, for example, Non-Patent Document 1).

JP-A-9-134725

Nature 458 (2009) p. 190-p. 193

  However, when the positive electrode active material is made into nano-sized fine powder, the electrode density of the positive electrode material obtained by using the fine powder decreases, and voids generated inside the positive electrode increase. In addition, when conductive carbon having nano-size and low bulk density is used as the conductive auxiliary agent, the electrode density of the positive electrode material is further reduced, and the voids generated inside the positive electrode are further increased. As a result, it is difficult to form a conductive network between the positive electrode active material and the conductive additive, and there is a problem that rapid charge / discharge performance is deteriorated. Furthermore, since the mechanical strength of the positive electrode material is reduced, the positive electrode material is easily peeled off from the positive electrode current collector, and there is a problem that the charge / discharge performance is greatly reduced.

  Therefore, the present invention has been made in view of such a situation, and an object thereof is to provide a positive electrode material for an electricity storage device having excellent rapid charge / discharge performance.

The positive electrode material for an electricity storage device of the present invention has at least one selected from the general formula LiM _x Fe _1-x PO ₄ (0 ≦ x <1, M is Nb, Ti, V, Cr, Mn, Co, Ni as the main crystal. A positive electrode active material containing crystallized glass on which an olivine-type crystal represented by the type) is deposited, and a conductive assistant containing conductive carbon black having a bulk density of 140 kg / m ³ or more. .

The conductive carbon black preferably has a BET specific surface area of 40 to 200 m ² / g.

  Furthermore, the positive electrode material preferably contains 85% to 92% of a positive electrode active material, 1% to 8% of a conductive additive, and 1% to 10% of a binder, in terms of mass%.

The crystallized glass preferably contains Li ₂ O 20 to 50%, Fe ₂ O ₃ 5 to 40%, and P ₂ O ₅ 20 to 50% in terms of mol% in terms of oxide.

The crystallized glass is further expressed in terms of mol% in terms of oxide, Nb ₂ O ₅ + TiO ₂ + V ₂ O ₅ + Cr ₂ O ₃ + MnO ₂ + CoO + NiO + SiO ₂ + B ₂ O ₃ + GeO ₂ + Al ₂ O ₃ + Ga ₂ O ₃ + Sb _{2 O 3} + _Bi 2 O ₃ is preferably contained 0.1 to 25%.

  The positive electrode active material preferably contains 0.2 to 3% of carbon by mass.

  ADVANTAGE OF THE INVENTION According to this invention, the positive electrode material for electrical storage devices excellent in rapid charge / discharge performance can be provided.

The positive electrode material for an electricity storage device of the present invention has at least one selected from the general formula LiM _x Fe _1-x PO ₄ (0 ≦ x <1, M is Nb, Ti, V, Cr, Mn, Co, Ni as the main crystal. A positive electrode active material containing crystallized glass on which an olivine-type crystal represented by (type) is deposited, and a conductive assistant containing conductive carbon black having a bulk density of 140 kg / m ³ or more.

In the present invention, by using the above-mentioned crystallized glass as the positive electrode active material, the movement speed of lithium ions in the positive electrode active material particles can be increased, and the particle diameter of the positive electrode active material can be increased. Specifically, it is preferable to contain Li ₂ O 20 to 50%, Fe ₂ O ₃ 5 to 40%, and P ₂ O ₅ 20 to 50% in terms of mol% in terms of oxide. The reason for limiting the composition as described above will be described below.

Li ₂ O is a main component of LiM _x Fe _1-x PO ₄ crystal. The content of Li ₂ O is preferably 20 to 50%, more preferably 25 to 45%. If the content of Li ₂ O is too small or too large, LiM _x Fe _1-x PO ₄ crystals are difficult to precipitate.

Fe ₂ O _{3 is} also a main component of LiM _x Fe _1-x PO ₄ crystal. The content of Fe ₂ O ₃ is preferably 5 to 40%, more preferably 15 to 35%, further preferably 25 to 35%, and more preferably 31.6 to 34%. Particularly preferred. When Fe ₂ content of O ₃ is too _{small, LiM x Fe 1-x PO} 4 crystal is less likely to precipitate. On the other hand, when the content of _Fe 2 _{O 3} is too _large, with LiM _{x Fe 1-x} PO ₄ crystal is less likely to precipitate, _Fe 2 _{O 3} crystals are likely to precipitate unwanted.

P ₂ O _{5 is} also a main component of LiM _x Fe _1-x PO ₄ crystal. The content of P ₂ O ₅ is preferably 20 to 50%, and more preferably 25 to 45%. When the content of P ₂ O ₅ is too small or too large, LiM _x Fe _1-x PO ₄ crystals are difficult to precipitate.

In addition to the above components, for example, TiO ₂ , V ₂ O ₅ , Cr ₂ O ₃ , MnO ₂ , CoO, and NiO are used as components of the LiM _x Fe _1-x PO ₄ crystal as components that further improve the glass forming ability. , for example, _{Nb 2 O 5, SiO 2,} B 2 O 3, GeO 2, Al 2 O 3, Ga 2 O 3, Sb 2 O 3, may contain _Bi 2 _{O 3.} These components are the total amount, and are mol% in terms of oxide, preferably 0.1 to 25%, more preferably 0.3 to 20%. If the total amount of the above components is too small, the above effect is difficult to obtain, and if it is too large, the amount of LiM _x Fe _1-x PO ₄ crystals precipitated tends to decrease.

Among these, Nb ₂ O ₅ is an effective component for obtaining a homogeneous precursor glass. The content of Nb ₂ O ₅ is preferably 0.1 to 10%, more preferably 0.2 to 5%, and still more preferably 0.3 to 3%. If the content of Nb ₂ O ₅ is too small, it is difficult to obtain a homogeneous precursor glass. On the other hand, when the content of Nb ₂ O ₅ is too large, the heterogeneous crystals such niobate iron upon crystallization is deposited, charge-discharge characteristics tend to deteriorate.

The positive electrode active material is a main crystal of the general formula LiM _x Fe _1-x PO ₄ (0 ≦ x <1, M is at least one selected from Nb, Ti, V, Cr, Mn, Co, Ni) Since the olivine type crystal represented by) has low electronic conductivity, the discharge capacity and rapid charge / discharge characteristics are improved by coating the surface of the positive electrode active material particles with a conductive layer such as carbon.

  The positive electrode active material preferably contains 0.2 to 3% of carbon by mass. Carbon is a component that enhances the electronic conductivity of the positive electrode active material. The content is more preferably 0.5 to 2.5%, and further preferably 1 to 2%. If the carbon content is too small, the electron conductivity of the positive electrode active material is lowered, and the discharge capacity tends to be lowered. On the other hand, if the carbon content is too large, the diffusion resistance of lithium ions at the interface of the positive electrode active material particles increases, and the discharge voltage tends to decrease.

In the crystallized glass, the degree of crystallinity of the LiM _x Fe _1-x PO ₄ crystal in mass% is preferably 70% or more, more preferably 80% or more, and 90% or more. Further preferred. If the crystallinity of the LiM _x Fe _1-x PO ₄ crystal is too low, the discharge capacity tends to decrease. In addition, although it does not specifically limit about an upper limit, In reality, it is preferable that it is 99% or less, and it is more preferable that it is 97% or less.

  The crystallinity is obtained by separating a diffraction line profile of 10 to 60 ° with a 2θ value obtained by powder X-ray diffraction measurement using CuKα ray into a crystalline diffraction line and an amorphous halo. It is done. Specifically, the integrated intensity obtained by peak-separating a broad diffraction line (amorphous halo) at 10 to 45 ° from the total scattering curve obtained by subtracting the background from the diffraction line profile is Ia, 10 When the total integrated intensity obtained by peak separation of each crystalline diffraction line detected at ˜60 ° is Ic, the crystallinity Xc can be obtained from the following equation.

    Xc = [Ic / (Ic + Ia)] × 100 (%)

  The positive electrode active material preferably contains an amorphous phase. By containing an amorphous phase on the surface of the active material particles, the diffusion resistance of lithium ions at the interface of the active material particles is reduced, and high-speed charge / discharge characteristics are improved.

  The average particle size of the positive electrode active material is preferably 0.01 to 30 μm, more preferably 0.05 to 20 μm, and further preferably 0.1 to 10 μm. If the average particle size of the positive electrode active material is too large, lithium ions present in the active material cannot be effectively occluded and released when charged and discharged, and the discharge capacity tends to decrease. On the other hand, if the average particle size of the positive electrode active material is too small, it tends to be difficult to produce a uniform electrode. In addition, since the specific surface area becomes too large and the positive electrode active material powder is difficult to disperse when producing a paste for forming an electrode, a large amount of binder and solvent are required. Furthermore, it is inferior to the applicability of the electrode forming paste, and it becomes difficult to form a positive electrode having a uniform thickness.

  In addition, in this invention, an average particle diameter points out the value computed from the observation image of the electron microscope of a positive electrode. Specifically, 20 positive electrode active material particles are randomly selected from an electron microscope image and calculated from an average value of their particle diameters. In addition, about flat particle | grains, let the average value of a long diameter and a short diameter be a particle diameter.

  Next, the manufacturing method of crystallized glass is demonstrated.

First, a raw material powder was prepared so as to have a glass composition containing Li ₂ O 20 to 50%, Fe ₂ O ₃ 5 to 40% and P ₂ O ₅ 20 to 50% in mol%, and the obtained raw material Precursor glass as a precursor is obtained from the powder by a melt quenching process, a sol-gel process, a chemical vapor synthesis process such as spraying a solution mist into a flame, a mechanochemical process, or the like. According to these processes, vitrification is easily promoted, and as a result, the remaining of unreacted raw materials and generation of magnetic impurities are less likely to occur.

  Crystallized glass is obtained by heat-treating the obtained precursor glass. The heat treatment of the precursor glass is performed, for example, in an electric furnace capable of controlling the temperature and the atmosphere.

  The heat treatment temperature is not particularly limited because it varies depending on the composition of the precursor glass and the desired crystal content, but is preferably at least the glass transition temperature, and more preferably the crystallization temperature or more. 500 ° C. or higher, preferably 550 ° C. or higher. If the heat treatment temperature is too low, crystal precipitation may be insufficient and the discharge capacity may be reduced. On the other hand, the upper limit of the heat treatment temperature is preferably 900 ° C., particularly preferably 850 ° C. If the heat treatment temperature is too high, different crystals are likely to precipitate, and the discharge capacity may be reduced.

  The heat treatment time is appropriately adjusted so that the crystallization of the precursor glass proceeds sufficiently. Specifically, it is preferably 10 to 180 minutes, particularly 20 to 120 minutes.

During the heat treatment, it is preferable to add an organic compound such as a surfactant to the precursor glass and perform firing in an inert or reducing atmosphere. According to this method, a positive electrode active material having an electron-conductive amorphous coating layer formed on the crystallized glass surface is obtained, so that the electron conductivity on the surface of the positive electrode active material is improved, and good rapidity can be achieved in an electricity storage device. Charge / discharge characteristics can be obtained. The amorphous coating layer also plays a role of suppressing elution of transition metal ions. In addition, since the organic compound exhibits a reducing action by firing, the valence of iron in the glass is likely to change to divalent when crystallized, and LiM _x Fe _1-x PO ₄ crystals are selectively selected at a high rate. Can get to.

  The addition amount of the organic compound is preferably 0.1 to 50 parts by mass, more preferably 1 to 30 parts by mass, and 1.5 to 20 parts by mass with respect to 100 parts by mass of the precursor glass. More preferably it is. If the amount of the organic compound added is too small, the above effect is difficult to obtain. On the other hand, when the amount of the organic compound added is too large, the potential difference between the positive electrode and the negative electrode in the electricity storage device becomes small, and a desired electromotive force may not be obtained.

  In the positive electrode material for an electricity storage device of the present invention, the conductive additive contains conductive carbon black. Since the conductive carbon black exhibits excellent conductivity when added in a small amount, the rapid charge / discharge performance can be improved.

The bulk density of the conductive carbon black is 140 kg / m ³ or more, and preferably 150 kg / m ³ or more. When the bulk density is small, the bond between the primary particles of conductive carbon black is weak, so that the conductive network tends to be cut by kneading during electrode paste preparation. As a result, rapid charge / discharge performance tends to be reduced. In addition, although it does not specifically limit about an upper limit, It is preferable that it is 300 kg / m < ³ > or less practically, and it is more preferable that it is 200 kg / m < ³ > or less.

Conductive carbon black is preferably a BET specific surface area of 40 to 200 m ² / g, more preferably 50 to 100 m ² / g, further preferably 55~80m ² / g. If the BET specific surface area is too small, it becomes difficult to form an electron conduction path in the positive electrode material, so that the discharge capacity is likely to decrease. on the other hand. If the BET specific surface area is too large, the porosity of the conductive carbon black increases, and the conductive network in the conductive carbon black tends to be cut. As a result, the conductivity of the conductive carbon black decreases, and the rapid charge / discharge performance decreases.

  In the present invention, examples of the binder include thermoplastic linear polymers such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), fluorine-based rubber, and styrene-butanediene rubber (SBR); Thermosetting resins such as conductive polyimide, polyamideimide, polyamide, phenol resin, epoxy resin, urea resin, melamine resin, unsaturated polyester resin, polyurethane; carboxymethylcellulose (including carboxymethylcellulose salts such as carboxymethylcellulose sodium; the same shall apply hereinafter). , Cellulose derivatives such as hydroxypropylmethylcellulose, hydroxypropylcellulose, hydroxyethylcellulose, ethylcellulose and hydroxymethylcellulose, polyvinyl alcohol, polyacrylamide Water-soluble polymers such as polyvinylpyrrolidone and copolymers thereof can be used.

  As the positive electrode current collector, for example, an aluminum foil or an aluminum alloy foil can be used. Examples of the aluminum alloy include alloys made of aluminum and elements such as magnesium, zinc, and silicon.

  The positive electrode material for an electricity storage device of the present invention is preferably% by mass and contains 85 to 92% of a positive electrode active material, 1 to 8% of a conductive additive, and 1 to 10% of a binder. The reason for limiting the composition as described above will be described below.

  The content of the positive electrode active material is preferably 85 to 92%, and more preferably 90 to 92%. When there is too little content of a positive electrode active material, the charge capacity and discharge capacity per unit mass of a positive electrode will fall easily. On the other hand, if the content of the positive electrode active material is too large, the contact area with the binder is reduced and the binding property is lowered, so that the positive electrode material is easily lost from the positive electrode current collector, and the charge capacity and discharge capacity are reduced. Tends to decrease.

  The content of the conductive assistant is preferably 1 to 8%, and more preferably 3 to 5%. When there is too little content of a conductive support agent, the electronic conductivity of a positive electrode will fall and rapid charge / discharge performance will fall easily. On the other hand, when there is too much content of a conductive support agent, since the ratio of a positive electrode active material will reduce, the charge capacity per unit mass of a positive electrode and discharge capacity will fall easily.

  The content of the binder is preferably 1 to 10%, and more preferably 3 to 7%. When the content of the binder is too small, the binding property between the positive electrode current collector and the positive electrode material is deteriorated, so that the positive electrode material is easily lost from the positive electrode current collector, and the charge capacity and the discharge capacity are easily reduced. On the other hand, since the ratio of a positive electrode active material will reduce when there are too many binders, the charge capacity and discharge capacity per unit mass of a positive electrode will fall.

  In the positive electrode of the present invention, a positive electrode active material, a conductive additive, and a binder are mixed and suspended in water or a solvent such as N-methylpyrrolidone to form a slurry. It can be produced by coating, drying and pressing an electric body to form a strip.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to this Example.

Example 1
(1) Preparation of positive electrode active material Lithium metaphosphate (LiPO ₃ ), lithium carbonate (Li ₂ CO ₃ ), ferric oxide (Fe ₂ O ₃ ) and niobium oxide (Nb ₂ O ₅ ) as raw materials, oxide The raw material powders were converted so as to have a composition of 35.1% Li ₂ O, 32.2% Fe ₂ O _3, 32.2% P ₂ O ₅ and 0.5% Nb ₂ O _{5 in} terms of mol% in terms of conversion. The mixture was prepared and melted in air at 1250 ° C. for 1 hour. Then, molten glass was poured into a pair of rolls, and a precursor glass was produced by forming into a film shape while rapidly cooling.

The obtained precursor glass is subjected to ball milling using Al ₂ O ₃ boulders of φ20 mm for 5 hours, then ball milling in alcohol using φ5 mm ZrO ₂ boulders for 40 hours, and further to φ0.3 mm. Bead milling in alcohol using ZrO ₂ beads was performed for 8 hours to obtain a precursor glass powder having an average particle size (D50) of 0.5 μm.

11.8 parts by mass (carbon equivalent) of polyethylene oxide nonylphenyl ether (HLB value: 13.3, mass average molecular weight: 660), which is a nonionic surfactant, as a carbon source with respect to 100 parts by mass of the precursor glass powder 7 parts by mass) and 60 parts by mass of pure water were sufficiently mixed and then dried at 100 ° C. for about 1 hour. Then, by heat treatment for 30 minutes at 800 ° C. under a nitrogen atmosphere, a carbon-containing layer formed on the surface, to obtain a positive electrode active material composed of LiFePO ₄ crystallized glass powder. When the obtained cathode active material was confirmed by a powder X-ray diffraction pattern, the diffraction line from LiFePO ₄ was confirmed.

(2) Production of positive electrode The positive electrode active material obtained above, conductive carbon black (conductive auxiliary agent 1) having a bulk density of 160 kg / m ³ and a BET specific surface area of 62 m ² / g as a conductive auxiliary agent, Polyvinylidene fluoride as a binder was weighed to a ratio of 90: 5: 5 (mass ratio), dispersed in N-methylpyrrolidone solvent, and sufficiently stirred with a rotating / revolving mixer to form a slurry. did.

Next, the obtained slurry was coated on a 20 μm thick aluminum foil as a positive electrode current collector using a doctor blade having a gap of 200 μm, dried at 70 ° C., passed between a pair of rotating rollers, and 1 t / An electrode sheet was obtained by pressing at cm ² . This electrode sheet was punched to a diameter of 11 mm with an electrode punching machine and dried under reduced pressure at a temperature of 170 ° C. for 10 hours to obtain a circular positive electrode.

(3) Production of test battery Next, the obtained positive electrode was placed on the lower lid of the coin cell with the aluminum foil surface facing down, and dried at 200 ° C. for 8 hours, and a counter electrode. Metallic lithium was laminated to produce a test battery. As the electrolytic solution, 1M LiPF ₆ solution / EC: DEC = 1: 1 (EC = ethylene carbonate, DEC = diethyl carbonate) was used. The test battery was assembled in an environment with a dew point temperature of −40 ° C. or lower.

(4) Charging / discharging test The charging / discharging test was performed as follows. Perform CC (constant current) charge (lithium ion release from the positive electrode active material) from open circuit voltage (OCV) to 4V at 30 ° C, and obtain the amount of electricity (charge capacity) charged in the unit mass of the positive electrode active material It was. Next, CC discharge (lithium ion occlusion in the positive electrode active material) was performed from 4 V to 2 V, and the amount of electricity (discharge capacity) discharged in the unit mass of the positive electrode active material was determined. Thereafter, CC charge / discharge was repeatedly performed at 2V to 4V to determine the charge / discharge capacity. The C rate was changed from 0.1 to 20 C, and the C rate for charging and discharging immediately thereafter was the same. The results are shown in Table 1.

(Comparative Example 1)
A test battery was prepared in the same manner as in Example 1 except that the conductive auxiliary agent was conductive carbon black (conductive auxiliary agent 2) having a bulk density of 30 kg / m ³ and a BET specific surface area of 800 m ² / g. It produced and the charge / discharge test was done. The results are shown in Table 1.

(Comparative Example 2)
Using lithium hydroxide monohydrate (LiOH.H ₂ O), iron oxalate (FeC ₂ O ₄ .2H ₂ O), diammonium hydrogen phosphate ((NH ₄ ) ₂ HPO ₄ ) as raw materials, mol% The raw materials were prepared so that the composition of Li ₂ O 25%, FeO 50%, and P ₂ O ₅ 25% was obtained, and pulverized and mixed with a ball mill so that the average particle size became 0.4 μm, and then 675 ° C. in a nitrogen atmosphere. For 24 hours to obtain LiFePO ₄ crystal powder.

The obtained crystal powder was mixed with a carbon source in the same manner as in Example 1 and then subjected to heat treatment to obtain a positive electrode active material made of LiFePO ₄ crystal powder having a carbon-containing layer formed on the surface. .

  Using the positive electrode active material thus obtained, a positive electrode was produced in the same manner as in Example 1. Furthermore, a test battery was produced in the same manner as in Example 1 except that the positive electrode was used, and a charge / discharge test was performed. The results are shown in Table 1.

  As is clear from Table 1, the 10 C rate charge capacity and discharge capacity in Example 1 were both as high as 122 mAh / g or more. On the other hand, the charge capacity and discharge capacity at 10 C rate in Comparative Examples 1 and 2 were as low as 42 mAh / g or less.

  The positive electrode material for an electricity storage device of the present invention is suitable as a positive electrode material for an electricity storage device such as a lithium ion non-aqueous secondary battery used for portable electronic devices, electric vehicles and the like.

Claims (6)

An olivine type crystal represented by the general formula LiM _x Fe _1-x PO ₄ (0 ≦ x <1, M is at least one selected from Nb, Ti, V, Cr, Mn, Co, Ni) is used as the main crystal. A positive electrode material for an electricity storage device, comprising: a positive electrode active material containing precipitated crystallized glass; and a conductive additive containing conductive carbon black having a bulk density of 140 kg / m ³ or more. The positive electrode material for an electricity storage device according to claim 1, wherein the conductive carbon black has a BET specific surface area of 40 to 200 m ² / g.   3. The positive electrode material for an electricity storage device according to claim 1, wherein the positive electrode active material contains 85 to 92% of a positive electrode active material, 1 to 8% of a conductive auxiliary agent, and 1 to 10% of a binder. Claim wherein the crystallized glass, which by mol% of oxide _equivalent, Li 2 O 20 to _50%, characterized in that it contains _Fe 2 O 3 5 to 40% and _P 2 _O 5 20 to 50% The positive electrode material for electrical storage devices in any one of 1-3. The crystallized glass is further expressed in terms of mol% in terms of oxide, Nb ₂ O ₅ + TiO ₂ + V ₂ O ₅ + Cr ₂ O ₃ + MnO ₂ + CoO + NiO + SiO ₂ + B ₂ O ₃ + GeO ₂ + Al ₂ O ₃ + Ga ₂ O ₃ + Sb ₂ The positive electrode material for an electricity storage device according to claim 4, comprising 0.1 to 25% of O ₃ + Bi ₂ O ₃ . The positive electrode active material according to claim 1, wherein the positive electrode active material contains 0.2 to 3% of carbon by mass.