JP6175906B2 - Negative electrode active material for power storage device and method for producing the same - Google Patents

Description

  The present invention relates to a method for producing a negative electrode active material used for an electricity storage device such as a lithium ion secondary battery used in a portable electronic device or an electric vehicle, for example.

  In recent years, with the widespread use of portable electronic devices, electric vehicles, and the like, there is an increasing demand for higher capacity and smaller size of power storage devices such as lithium ion secondary batteries. If the capacity of the electricity storage device is increased, it will be easy to reduce the size of the battery. Therefore, there is an urgent need to develop the capacity of the electricity storage device.

For example, high potential type LiCoO ₂ , LiCo _1-x Ni _x O ₂ , LiNiO ₂ , LiMn ₂ O _{4 and the} like are widely used as the positive electrode active material for lithium ion secondary batteries. On the other hand, a carbon material is generally used for the negative electrode active material. These materials function as an electrode active material that reversibly occludes and releases lithium ions by charging and discharging, and a so-called rocking chair type secondary battery that is electrochemically connected by a non-aqueous electrolyte or a solid electrolyte. Configure. For example, a binder or a conductive auxiliary agent is added to these electrode active materials, and the electrode active material is used as an electrode by applying it to the surface of a metal foil or the like that serves as a current collector.

  Examples of the carbon material used for the negative electrode active material include graphitic carbon material, pitch coke, fibrous carbon, and soft carbon. However, the commonly used graphitic carbon material has a problem that it is difficult to increase the capacity of the battery because only 0.17 lithium can be inserted and extracted per one carbon atom. Specifically, even if a stoichiometric amount of lithium insertion capacity can be realized, the limit of the battery capacity of the graphitic carbon material is about 372 mAh / g.

  A negative electrode active material containing Si and Sn has been proposed as a negative electrode active material that can occlude and release lithium ions and has a higher capacity density than a negative electrode active material made of a carbon material (for example, a patent) Reference 1). However, although the negative electrode active material containing Si or Sn is excellent in the initial charge / discharge efficiency (ratio of the discharge capacity to the initial charge capacity), the volume change due to the lithium ion occlusion and release reaction during charge / discharge is remarkable. Since it is large, the negative electrode active material is structurally deteriorated and repeatedly cracked when repeatedly charged and discharged. As cracks progress, in some cases, cavities are formed in the negative electrode active material and may be pulverized. When a crack occurs in the negative electrode active material, the electron conduction network is divided, so that there is a problem that the discharge capacity (cycle characteristics) after repeated charge and discharge is lowered.

Furthermore, a glass material made of SnO and P ₂ O ₅ has been proposed as a negative electrode active material excellent in both high capacity density and cycle characteristics (see, for example, Patent Document 2).

JP 2000-36323 A JP 2011-187434 A

  An electricity storage device using an oxide material such as SnO as a negative electrode has a problem that the charge / discharge efficiency of the initial cycle (ratio of the initial discharge capacity to the initial charge capacity) is low. This is considered to be because, in the first charging process, some of carrier ions and electrons in the positive electrode material are consumed in an irreversible reaction for reducing an oxide material such as SnO.

  This invention is made | formed in view of the above situations, and it aims at providing the manufacturing method of the negative electrode active material for electrical storage devices which has a favorable initial stage charge / discharge characteristic.

The method for producing a negative electrode active material for an electricity storage device according to the present invention is to reduce SnO _x to metal Sn by supplying a reducing gas to an oxide material containing SnO _x (0 <x ≦ 2) and performing a heat treatment. A reduction step.

  Moreover, it is preferable that the said reducing gas contains the substance whose free energy of the Gibbs produced | generated by oxidation is smaller than metal Sn in the atmospheric temperature of the said reduction | restoration process.

Furthermore, it is preferable that the reducing gas is N ₂ 90 to 99.5% and H ₂ 0.5 to 10% by volume.

  Moreover, it is preferable that the atmospheric temperature of the said reduction | restoration process is 500 degreeC or more.

In the method for producing a negative electrode active material for an electricity storage device of the present invention, the oxide material is mol% in terms of oxide, SnO 40 to 90%, P ₂ O ₅ 0 to 45%, SiO ₂ 0 to 60%, _{B 2 O 3 0~30%, R} 2 O 0~50% (R = Li, Na, K), preferably contains 2 O 3 10~60% P 2 O 5 + SiO 2 + B.

  Furthermore, the oxide material preferably contains an amorphous phase.

  The negative electrode active material for an electricity storage device of the present invention is preferably produced by the production method.

  The negative electrode active material for an electricity storage device of the present invention is preferably formed by dispersing metal Sn particles.

  The negative electrode active material for an electricity storage device of the present invention preferably detects a diffraction line having a peak position at a 2θ value of 29 to 33 ° in a diffraction line profile obtained by powder X-ray diffraction measurement using CuKα rays.

  According to the production method of the present invention, it is possible to provide a negative electrode active material for an electricity storage device having good initial charge / discharge characteristics.

The method for producing a negative electrode active material for an electricity storage device according to the present invention is to reduce SnO _x to metal Sn by supplying a reducing gas to an oxide material containing SnO _x (0 <x ≦ 2) and performing a heat treatment. A reduction step.

In the reduction step, by supplying the reducing gas and performing the heat treatment, the oxide material and the reducing gas come into contact with each other, and SnO _x in the oxide material can be efficiently reduced to metal Sn. It becomes easy to improve charge / discharge characteristics.

  For the heat treatment, an electric heating furnace, a rotary kiln, a microwave heating furnace, a high-frequency heating furnace, or the like can be used.

The holding time when the heat treatment is performed is preferably 20 to 1000 minutes, and more preferably 60 to 500 minutes. If the holding time is too short, the applied thermal energy is small, so that SnO _x in the oxide material is hardly reduced to metal Sn. On the other hand, if the holding time is too long, the reduced metal Sn particles are likely to be coarsened, and the cycle characteristics of the negative electrode active material are significantly deteriorated.

It is preferable that the reducing gas contains a substance whose Gibbs free energy generated by oxidation is smaller than that of metal Sn at the atmospheric temperature of the reduction step. Therefore, when the oxide material SnO _x is reduced to metal Sn and the reducing agent is oxidized, it becomes thermodynamically stable, and the metal Sn particles are stably dispersed in the obtained negative electrode active material for an electricity storage device. It becomes possible. As a result, it is possible to improve the initial charge / discharge characteristics.

Further, when the reducing gas contains a kind of gas selected from H ₂ , NH ₃ , CO, H ₂ S and SiH ₄ , the Gibbs free energy generated by oxidation becomes smaller than that of metal Sn, and oxidation It is preferable because SnO _x of the material is easily reduced to metal Sn. The reducing gas preferably contains one kind of gas selected from H ₂ , NH ₃ and CO, and particularly preferably contains H ₂ gas.

Furthermore, it is preferable that the reducing gas is N ₂ 90 to 99.5% and H ₂ 0.5 to 10% by volume because the risk of explosion or the like is very low, and N ₂ 92 It is particularly preferred that ˜99% and H ₂ is 1-4%.

The atmospheric temperature is preferably 500 ° C. or higher, more preferably 550 to 900 ° C., and particularly preferably 600 to 800 ° C. If the ambient temperature is too low, the applied thermal energy is small, and therefore SnO _x in the oxide material is difficult to be reduced to metal Sn. On the other hand, when the atmospheric temperature is too high, the reduced metal Sn particles are likely to be coarsened, and the cycle characteristics of the negative electrode active material are significantly deteriorated.

The oxide material, in mole percent _{composition, SnO 40~90%, P 2 O} 5 0~45%, SiO 2 0~60%, B 2 O 3 0~30%, R 2 O 0~50% ( R = Li, Na, K), P ₂ O ₅ + SiO ₂ + B ₂ O ₃ It is preferable to contain 10 to 60%. The reason for limiting the composition in this way will be described below. In the description of the composition below, “%” means “mol%” unless otherwise specified.

SnO is an active material component that serves as a site for occluding and releasing lithium ions. The SnO content is preferably 40 to 90%, more preferably 45 to 85%, still more preferably 48 to 82%, and particularly preferably 50 to 80%. When there is too little content of SnO, the discharge capacity per unit mass of a negative electrode active material will become small, and there exists a tendency for the charge / discharge efficiency at the time of first time charge / discharge to fall. On the other hand, if the content of SnO is too large, the amorphous component in the negative electrode active material is relatively reduced, so that volume changes associated with insertion and extraction of lithium ions during charge and discharge cannot be mitigated, and cycle characteristics Decreases. In the present invention, the content of SnO is oxidized tin component other than SnO (SnO _2, etc.) also refers to that summed in terms of SnO.

P ₂ O ₅ is a network-forming oxide and has an effect of improving the cycle characteristics by including lithium ion storage and release sites in SnO. The content of P ₂ O ₅ is preferably 0 to 45%, more preferably 0 to 42%, further preferably 0 to 40%, and particularly preferably 0 to 38%. . When the content of P ₂ O ₅ is too large, the water resistance tends to deteriorate. In addition, by absorbing moisture, a large amount of different types of crystals (for example, SnHPO ₄ ) are formed, and the cycle characteristics are likely to deteriorate.

SiO _{2 is} also a network-forming oxide and includes the lithium ion storage and release sites in SnO, and has the effect of improving cycle characteristics. The content of SiO ₂ is preferably 0 to 60%, preferably 0 to 55%, more preferably 0 to 53%, further preferably 0 to 50%, 45% is particularly preferred. When the content of SiO ₂ is too large, ionic conductivity will decrease, the discharge capacity tends to decrease.

B ₂ O ₃ also includes a lithium ion occlusion and release site in SnO as a network-forming oxide, and functions as a solid electrolyte to which Li ions can move. The content of B ₂ O ₃ is preferably 0 to 30%, more preferably 0 to 25%, further preferably 0 to 20%, and particularly preferably 0 to 15%. preferable. If the B ₂ O ₃ content is too large, coordination bond to Sn component is strong, there is a tendency to lower the initial charge and discharge efficiency.

The total amount of P ₂ O ₅ , SiO ₂ and B ₂ O ₃ is preferably 10 to 60%, more preferably 15 to 55%, still more preferably 18 to 52%, 20 It is particularly preferred that it is ˜50%. When the total amount of P ₂ O ₅ , SiO ₂ , and B ₂ O ₃ is too large, the oxide matrix component that includes the Sn component increases, and thus the charge / discharge capacity tends to decrease. On the other hand, if the total amount of P ₂ O ₅ , SiO ₂ , and B ₂ O ₃ is too small, the volume change of Sn atoms associated with insertion and extraction of lithium ions during charge / discharge cannot be alleviated, resulting in structural deterioration. The characteristic tends to deteriorate.

R ₂ O (R = Li, Na) is a component that improves the ionic conductivity of the oxide matrix other than the SnO _x component. The content of R ₂ O is preferably 0 to 50%, more preferably 1 to 45%, further preferably 3 to 43%, particularly preferably 5 to 40%, It is particularly preferably 7 to 35%. If the content of R ₂ O is too large, a large amount of heterogeneous crystals (eg, Li ₃ PO ₄ , Li ₄ SiO ₄ ) composed of P ₂ O ₅ , SiO ₂ , B ₂ O ₃ and R ₂ O are formed, and the cycle The characteristic tends to deteriorate. On the other hand, if the content of R ₂ O is too small, carrier ions are likely to be trapped in an oxide matrix other than the SnO _x component during the initial charge, and the initial charge / discharge efficiency tends to decrease. In the case where the power storage device is a power storage device in which the carrier ions are Li ions, such as a lithium ion secondary battery or a lithium ion capacitor, R ₂ O is preferably Li ₂ O, and the carrier such as a sodium ion secondary battery In the case of an electricity storage device in which ions are Na ions, R ₂ O is preferably Na ₂ O.

In addition to the above components, various components can be further added to the oxide material. For example, the total amount of MnO, CuO, ZnO, MgO, CaO, and Al ₂ O ₃ is preferably 0 to 25%, more preferably 0 to 23%, and more preferably 0 to 21%. Further preferred is 0.1 to 20%. When there are too many of these components, the structure becomes disordered and an amorphous material is easily obtained, but the network made of the network-forming oxide is easily cut. As a result, the volume change of the negative electrode active material accompanying charge / discharge cannot be relaxed, and the cycle characteristics may be deteriorated.

  The oxide material is preferably a material containing an amorphous phase. In this case, the crystallinity of the oxide material is preferably 95% or less, more preferably 50% or less, further preferably 20% or less, and substantially amorphous. Particularly preferred. The smaller the degree of crystallinity (the greater the proportion of the amorphous phase), the more the volume change during repeated charging / discharging can be alleviated, which is advantageous from the viewpoint of suppressing the decrease in discharge capacity. Note that “substantially amorphous” means that the crystallinity is substantially 0% (specifically, 0.1% or less). Specifically, the following CuKα ray In a powder X-ray diffraction measurement using, a crystal diffraction line is not detected.

  The degree of crystallinity is determined from a diffraction line profile of 10 to 60 degrees with 2θ values obtained by powder X-ray diffraction measurement using CuKα rays. 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 (%)

Furthermore, it is preferable that the mixture contains an aggregation inhibitor. By containing the aggregation inhibitor, it becomes possible to prevent the formation of aggregates in the mixture and to reduce SnO _x in the oxide material to metal Sn in a shorter time. The aggregation preventing agent is preferably a carbon material, more preferably conductive carbon, and particularly preferably acetylene black having high electron conductivity.

  It is preferable that the mixture contains 50 to 97% of an oxide material, 3 to 50% of a reducing agent, and 0 to 30% of an anti-aggregation agent in terms of mass%. With the above configuration, a negative electrode active material having good initial charge / discharge efficiency and stable cycle characteristics can be obtained.

  The oxide material is manufactured, for example, by heating and melting raw material powder to vitrify it. Here, it is preferable to melt the raw material powder in a reducing atmosphere or an inert atmosphere.

The oxide material easily changes the oxidation state of Sn atoms depending on melting conditions, and when melted in the air, undesired crystals such as SnO ₂ and SnP ₂ O ₇ are easily formed. As a result, the initial charge / discharge efficiency and cycle characteristics of the negative electrode material may be reduced. Therefore, by performing melting in a reducing atmosphere or an inert atmosphere, it is possible to suppress an increase in the valence of Sn ions in the oxide material, to suppress formation of unwanted crystals, and to be excellent in initial charge / discharge efficiency and cycle characteristics. It is possible to obtain an electricity storage device.

In order to melt in a reducing atmosphere, it is preferable to supply a reducing gas into the melting tank. The reducing gas, by _{volume%, N 2 90~99.5%, H} 2 0.5~10%, in particular _{N 2 92~99%, H} 2 is be used from 1 to 8% of the mixed gas preferable.

  When melting in an inert atmosphere, it is preferable to supply an inert gas into the melting tank. As the inert gas, it is preferable to use any of nitrogen, argon, and helium.

  The reducing gas or the inert gas may be supplied to the upper atmosphere of the molten glass in the melting tank, may be supplied directly from the bubbling nozzle into the molten glass, or both methods may be performed simultaneously.

  The shape of the negative electrode active material is preferably powder. The average particle diameter is preferably 0.1 to 20 μm, more preferably 0.2 to 15 μm, further preferably 0.3 to 10 μm, and preferably 0.5 to 5 μm. Particularly preferred. The maximum particle size is preferably 150 μm or less, more preferably 100 μm or less, further preferably a maximum particle size of 75 μm or less, and particularly preferably 55 μm or less. If the average particle size or the maximum particle size is too large, the volume change of the negative electrode active material associated with insertion and extraction of lithium ions during charge / discharge cannot be alleviated, and it tends to peel off from the current collector. As a result, the cycle characteristics tend to deteriorate significantly. On the other hand, if the average particle size is too small, the powder is in a poorly dispersed state when formed into a paste, and it tends to be difficult to produce a uniform electrode.

  Here, the average particle size and the maximum particle size are D50 (50% volume cumulative diameter) and D90 (90% volume cumulative diameter), respectively, in terms of the median diameter of primary particles, and were measured by a laser diffraction particle size distribution analyzer. Value.

  In order to obtain a powder of a predetermined size, a general pulverizer or classifier is used. For example, a mortar, a ball mill, a vibrating ball mill, a satellite ball mill, a planetary ball mill, a jet mill, a sieve, a centrifugal separator, an air classification, or the like is used.

  The negative electrode active material for an electricity storage device obtained by the above manufacturing method is preferably formed by dispersing metal Sn particles. When metal Sn particles are dispersed in the negative electrode active material, the initial charge / discharge efficiency is excellent.

  In a diffraction line profile obtained by powder X-ray diffraction measurement using CuKα ray, a diffraction line having a peak position at 2θ value of 29 to 33 ° is a metal crystal phase of metal Sn (tetragonal system, space group I41 / amd ( 141)), indicating that metal Sn particles are formed in the oxide material.

  The peak positions of diffraction lines attributed to the metal Sn are detected at 30.6 ° (Miller index (hkl) = (200)) and 32.0 ° (Miller index (hkl) = (101)). Therefore, when metal Sn particles are present in the oxide material, two diffraction lines are detected at around 30.6 ° and around 32.0 °, but both diffraction lines overlap to form one diffraction line. It may be detected.

  The negative electrode active material for an electricity storage device of the present invention has a half width of a diffraction line having a peak position at a 2θ value of 29 to 33 ° in a diffraction line profile obtained by powder X-ray diffraction measurement using CuKα rays. It is preferably at least 0 °, more preferably at least 0.05 °, even more preferably at least 0.07 °, particularly preferably at least 0.1 °. When the half width of the diffraction line is sufficiently large, the crystallite size of the metal Sn particles in the negative electrode active material is nano-order (for example, 0.1 to 100 nm), so that lithium ions or sodium ions are occluded by the charging reaction. However, volume expansion hardly occurs, and as a result, cycle characteristics are excellent. On the other hand, when the half-width of the diffraction line is too small, the size of the metal Sn particles is large (micron order or more), and therefore, when lithium ions or sodium ions are occluded by the charging reaction, a large volume expansion occurs locally. Occurs and the cycle characteristics tend to deteriorate.

  The negative electrode active material for an electricity storage device obtained by the production method of the present invention is used as a negative electrode material for an electricity storage device by adding a binder or a conductive additive.

  Examples of the binder include cellulose derivatives such as carboxymethylcellulose, hydroxypropylmethylcellulose, hydroxypropylcellulose, hydroxyethylcellulose, ethylcellulose, hydroxymethylcellulose, and water-soluble polymers such as polyvinyl alcohol; thermosetting polyimide, phenolic resin, epoxy resin, urea Examples thereof include thermosetting resins such as resins, melamine resins, unsaturated polyester resins, and polyurethanes; polyvinylidene fluoride.

  Examples of the conductive assistant include highly conductive carbon black such as acetylene black and ketjen black, carbon powder such as graphite, and carbon fiber.

  The negative electrode material for an electricity storage device can be used as an anode for an electricity storage device by applying it to the surface of a metal foil or the like that serves as a current collector.

  Examples of the negative electrode active material for an electricity storage device of the present invention will be described below with reference to examples applied to the use of a nonaqueous secondary battery, but the present invention is not limited to these examples.

(1) Production of Oxide Material The oxide materials listed in Table 1 are tin oxide (SnO) or a composite oxide of tin and phosphorus (stannous pyrophosphate: Sn ₂ P ₂ O ₇ ) as a raw material. Raw material powder was prepared using other various oxides, carbonate raw material, liquid phosphoric acid, metal powder raw material, carbon raw material and the like. The raw material was put into a quartz crucible and melted in a nitrogen atmosphere using an electric furnace. Note that Example 1 and Comparative Example 1 were melted at 950 ° C. for 40 minutes, and Example 2 and Comparative Example 2 were melted at 1300 ° C. for 40 minutes.

  Next, the molten glass was molded while being rapidly cooled by pouring it between a pair of rotating rollers to obtain a film glass having a thickness of 0.1 to 2 mm. This film-like glass was pulverized at 100 rpm for 3 hours using a ball mill containing zirconia balls having a diameter of 1 to 3 cm, and then passed through a resin sieve having a mesh size of 120 μm. Material coarse powder). Subsequently, the glass coarse powder was subjected to air classification to obtain glass powder (oxide material powder) having an average particle diameter of 2 μm and a maximum particle diameter of 28 μm.

  When the structure of the oxide material powder was identified by powder X-ray diffraction measurement, it was amorphous and no crystals were detected.

(2) Production of negative electrode active material 5 g of the obtained oxide material was green compacted and heat-treated under the conditions shown in Table 1.

  Next, the fired product was coarsely pulverized in an alumina mortar and then finely pulverized in an agate mortar and passed through a resin sieve having an opening of 20 μm to obtain a powder having an average particle size of 3 to 15 μm.

  The structure of the obtained negative electrode active material was identified by powder X-ray diffraction measurement. The results are shown in Table 1.

(3) Production of negative electrode The obtained negative electrode active material, conductive additive and binder were weighed to a mass ratio of 80: 5: 15, dispersed in dehydrated N-methylpyrrolidone, and then rotated. -It stirred sufficiently with the revolution mixer and was made into the slurry. Here, conductive carbon black (SuperC65, manufactured by Timcal) was used as the conductive auxiliary agent, and thermosetting polyimide resin was used as the binder.

  Next, using a doctor blade with a gap of 75 μm, the obtained slurry was coated on a 20 μm thick copper foil as a negative electrode current collector, vacuum-dried with a dryer at 70 ° C., and then between a pair of rotating rollers. An electrode sheet was obtained by pressing through. 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 200 ° C. for 8 hours to obtain a circular working electrode (a negative electrode for a non-aqueous secondary battery).

(4) Production of test battery Next, the obtained negative electrode was placed on the lower lid of the coin cell with the copper foil surface facing down, and dried at 70 ° C. under reduced pressure for 8 hours on a polypropylene porous with a diameter of 16 mm. A test battery was manufactured by laminating a separator made of a membrane (Cellguard # 2400 manufactured by Hoechst Celanese) and metallic lithium as a counter electrode. 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.

(5) Charge / Discharge Test The amount of electricity charged to the negative electrode active material of unit mass by performing CC (constant current) charge (lithium ion occlusion to the negative electrode active material) from 1 V to 0 V at 30 ° C. (Charge capacity) was determined. Next, CC discharge (lithium ion release from the negative electrode active material) was performed from 0 V to 1 V, and the amount of electricity (discharge capacity) discharged from the negative electrode active material of unit mass was obtained. The C rate was 0.2C. Table 1 shows the results of the charge / discharge characteristics. The initial charge / discharge efficiency refers to the ratio of the initial discharge capacity to the initial charge capacity.

  As described above, since the negative electrode active materials of Examples 1 and 2 were produced by performing heat treatment in a reducing atmosphere, the initial discharge capacity was as high as 492 to 668 mAh / g, and the initial charge and discharge efficiency was 54. It was as good as 7 to 55.0%. On the other hand, since the negative electrode active materials of Comparative Examples 1 and 2 were not subjected to heat treatment in a reducing atmosphere, the initial discharge capacity was as high as 528 to 640 mAh / g, but the initial charge and discharge efficiency was 45.3 to 46.6. % Was low.

  The negative electrode active material for an electricity storage device obtained by the present invention can be used for applications such as a main power source for mobile communication devices, portable electronic devices, electric bicycles, electric motorcycles, electric vehicles, and the like.

Claims (5)

In mole percent oxide _{equivalent, SnO 40~90%, P 2 O} 5 0~45%, SiO 2 0~60%, B 2 O 3 0~30%, R 2 O 0~50% (R = Li _{, Na, K),} to reduce the oxide materials containing 2 O 3 10~60% P 2 O 5 + SiO 2 + B, by a row Ukoto heat treatment by supplying a reducing gas to Sn O to metallic Sn A method for producing a negative electrode active material for an electricity storage device. _{2. The} method for producing a negative electrode active material for an electricity storage device according to claim 1, wherein the reducing gas is a kind of gas selected from H ₂ , NH ₃ , CO, H ₂ S, and SiH ₄ . _{2. The} method for producing a negative electrode active material for an electricity storage device according to claim 1, wherein the reducing gas is N ₂ 90 to 99.5% and H ₂ 0.5 to 10% by volume. .   The method for producing a negative electrode active material for an electricity storage device according to any one of claims 1 to 3, wherein an atmospheric temperature in the reduction step is 500 ° C or higher. Wherein the oxide material to be subjected to the reduction step, the manufacturing method of the negative electrode active material for an electricity storage device according to any one of claims 1 to 4, characterized in that it contains an amorphous phase.