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WO2018131627A1 - Mélange d'électrodes pour batterie secondaire au sodium-ion et son procédé de fabrication - Google Patents

Mélange d'électrodes pour batterie secondaire au sodium-ion et son procédé de fabrication Download PDF

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WO2018131627A1
WO2018131627A1 PCT/JP2018/000400 JP2018000400W WO2018131627A1 WO 2018131627 A1 WO2018131627 A1 WO 2018131627A1 JP 2018000400 W JP2018000400 W JP 2018000400W WO 2018131627 A1 WO2018131627 A1 WO 2018131627A1
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electrode mixture
sodium ion
powder
solid electrolyte
ion secondary
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Japanese (ja)
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純一 池尻
英郎 山内
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Nippon Electric Glass Co Ltd
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Nippon Electric Glass Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
    • H01M10/0562—Solid materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to an electrode mixture for a sodium ion secondary battery used for an electricity storage device such as a sodium ion secondary battery and a method for producing the same.
  • Lithium ion secondary batteries have established themselves as high-capacity and lightweight power supplies that are indispensable for mobile devices and electric vehicles.
  • the current lithium ion secondary battery mainly uses a flammable organic electrolyte as an electrolyte, and there is a concern about the risk of ignition and the like.
  • development of a lithium ion all-solid battery using a solid electrolyte instead of an organic electrolyte has been underway (see, for example, Patent Document 1).
  • the all-solid battery as described above includes a positive electrode layer, a negative electrode layer, and a sodium ion conductive solid electrolyte layer.
  • the positive electrode layer and the negative electrode layer are generally composed of a mixture (electrode mixture) of an active material powder that occludes or releases sodium ions and electrons during charge and discharge and a solid electrolyte powder.
  • Patent Document 3 discloses an electrode mixture obtained by firing an active material precursor powder made of crystalline glass powder and a raw material powder (electrode mixture precursor) made of solid electrolyte powder, and fusing and integrating the powders. Is described.
  • the electrode mixture described in Patent Document 3 has a problem that the ion conduction path is not sufficiently formed between the active material powder and the solid electrolyte powder, and the discharge capacity is small.
  • an object of the present invention is to provide an electrode mixture for a sodium ion secondary battery in which an ion conduction path is sufficiently formed between the active material powder and the solid electrolyte powder and the discharge capacity is large. To do.
  • the electrode mixture for a sodium ion secondary battery of the present invention comprises a sintered body of an electrode mixture precursor powder containing an active material precursor powder and a sodium ion conductive solid electrolyte powder, and has a porosity of 45. % Or less.
  • the electrode mixture of the present invention has a feature that the porosity is as small as 45% or less, and the adhesiveness between the active material powder and the solid electrolyte powder is high, so that an ion conduction path is sufficiently formed and the discharge capacity is high.
  • the electrode mixture for a sodium ion secondary battery according to the present invention has an active material precursor powder (i) at least one transition metal selected from the group consisting of Cr, Fe, Mn, Co, Ni, Ti and Nb. It is preferable to contain an element, (ii) at least one element selected from P, Si and B, and (iii) O.
  • the solid electrolyte powder preferably contains at least one selected from Al, Y, Zr, Si and P, Na, and O.
  • the solid electrolyte powder preferably contains at least one selected from ⁇ -alumina, ⁇ ′′ -alumina, and NASICON type crystals.
  • the average particle diameter of the active material precursor powder and / or the solid electrolyte powder is preferably 0.01 to 15 ⁇ m. In this way, the number of ion conduction paths can be increased, and the discharge capacity can be further improved.
  • the sodium ion secondary battery of the present invention is characterized by using the above-mentioned electrode mixture for sodium ion secondary batteries.
  • the method for producing an electrode mixture for a sodium ion secondary battery comprises a step of slurrying an electrode mixture precursor powder comprising (a) an active material precursor powder and a sodium ion conductive solid electrolyte powder. (B) applying the slurry obtained on the substrate and drying it to produce an electrode mixture precursor sheet; and (c) pressing the electrode mixture precursor sheet and firing it. It is characterized by including.
  • the adhesiveness between the active material powder and the solid electrolyte powder can be effectively enhanced by pressing and firing the electrode mixture precursor sheet. Therefore, for example, even if the active material precursor powder is made of crystalline glass with low softening fluidity, it is possible to sufficiently form an ion conduction path in the electrode mixture.
  • the electrode mixture precursor sheet is preferably isotropically pressed or uniaxially pressed.
  • the electrode mixture precursor sheet is preferably pressed at a pressure of 3 MPa or more.
  • the method for producing a battery for a sodium ion secondary battery of the present invention comprises (a) slurrying an electrode mixture precursor powder containing an active material precursor powder and a sodium ion conductive solid electrolyte powder. b) A step of producing a laminate sheet in which an electrode mixture precursor layer is formed on a solid electrolyte sheet by applying and drying the obtained slurry on a solid electrolyte sheet; and (c) a laminate. And a step of firing after pressing the sheet.
  • the adhesion between the active material powder and the solid electrolyte powder in the electrode mixture can be enhanced, and at the same time, the adhesion between the electrode mixture layer and the solid electrolyte sheet can be enhanced. Therefore, it is possible to sufficiently form both ion conduction paths in the electrode mixture and between the electrode mixture and the solid electrolyte sheet.
  • the laminate sheet is isotropically pressed or uniaxially pressed.
  • the laminate sheet In the method for producing a sodium ion secondary battery of the present invention, it is preferable to press the laminate sheet at a pressure of 3 MPa or more.
  • an electrode mixture for a sodium ion secondary battery in which an ion conduction path is sufficiently formed between the active material powder and the solid electrolyte powder and the discharge capacity is large.
  • SEM 4 is a SEM (scanning electron microscope) image of a cross section of a positive electrode mixture layer in a test battery of Example 3. It is the image which binarized the SEM image of FIG. 4 is a SEM image of a cross section of a positive electrode mixture layer in a test battery of Comparative Example 3. It is the image which binarized the SEM image of FIG.
  • the electrode mixture for a sodium ion secondary battery of the present invention comprises a sintered body of an electrode mixture precursor powder including an active material precursor powder and a sodium ion conductive solid electrolyte powder.
  • the active material precursor powder becomes an active material powder by firing.
  • the active material powder includes a positive electrode active material powder and a negative electrode active material powder, and occludes and releases sodium ions during charge and discharge.
  • Examples of the active material precursor powder include glass powder.
  • the active material precursor powder is usually accompanied by crystallization by firing, but may not be crystallized. That is, the active material powder may contain crystals (crystallized glass) or amorphous.
  • the active material precursor powder is selected from (i) at least one transition metal element selected from the group consisting of Cr, Fe, Mn, Co, Ni, Ti and Nb, and (ii) P, Si and B. And (iii) those containing O.
  • the positive electrode active material precursor powder a powder containing Na 2 O 8 to 55%, CrO + FeO + MnO + CoO + NiO 10 to 70%, P 2 O 5 + SiO 2 + B 2 O 3 15 to 70% in terms of mol% in terms of oxide. Can be mentioned. The reason why each component is limited in this way will be described below. In the following description regarding the content of each component, “%” means “mol%” unless otherwise specified. “ ⁇ + ⁇ +...” Means the total amount of each corresponding component.
  • Na 2 O serves as a supply source of sodium ions that move between the positive electrode active material and the negative electrode active material during charge and discharge.
  • the content of Na 2 O is preferably 8 to 55%, 15 to 45%, particularly 25 to 35%. If the amount of Na 2 O is too small, sodium ions contributing to occlusion and release decrease, and the discharge capacity tends to decrease. On the other hand, when there is too much Na 2 O, different crystals that do not contribute to charging / discharging such as Na 3 PO 4 tend to precipitate, and the discharge capacity tends to decrease.
  • CrO, FeO, MnO, CoO, and NiO are components that act as a driving force for occlusion and release of sodium ions by causing a redox reaction by changing the valence of each transition element during charge and discharge.
  • NiO and MnO have a great effect of increasing the redox potential.
  • FeO has high structural stabilization in charge and discharge, and it is easy to improve cycle characteristics.
  • the content of CrO + FeO + MnO + CoO + NiO is preferably 10 to 70%, 15 to 60%, 20 to 55%, 23 to 50%, 25 to 40%, particularly preferably 26 to 36%.
  • P 2 O 5 , SiO 2 and B 2 O 3 form a three-dimensional network structure, they have an effect of stabilizing the structure of the positive electrode active material.
  • P 2 O 5 and SiO 2 are preferable because of excellent ion conductivity, and P 2 O 5 is most preferable.
  • the content of P 2 O 5 + SiO 2 + B 2 O 3 is 15 to 70%, preferably 20 to 60%, particularly preferably 25 to 45%. If the amount of P 2 O 5 + SiO 2 + B 2 O 3 is too small, the discharge capacity tends to decrease when the battery is repeatedly charged and discharged.
  • the content of each component of P 2 O 5 , SiO 2 and B 2 O 3 is preferably 0 to 70%, 15 to 70%, 20 to 60%, and particularly preferably 25 to 45%.
  • vitrification can be facilitated by incorporating various components in addition to the above components within a range not impairing the effects of the present invention.
  • examples of such components include MgO, CaO, SrO, BaO, ZnO, CuO, Al 2 O 3 , GeO 2 , Nb 2 O 5 , ZrO 2 , V 2 O 5 , and Sb 2 O 5 in oxide notation.
  • Al 2 O 3 serving as a network-forming oxide and V 2 O 5 serving as an active material component are preferable.
  • the total content of the above components is preferably 0 to 30%, 0.1 to 20%, particularly preferably 0.5 to 10%.
  • the active material crystals that act as the positive electrode active material powder include Na, M (M is at least one transition metal element selected from Cr, Fe, Mn, Co and Ni), sodium transition metal phosphorus containing P and O.
  • Examples include acid salt crystals. Specific examples include Na 2 FeP 2 O 7 , NaFePO 4 , Na 3 V 2 (PO 4 ) 3 , Na 2 NiP 2 O 7 , Na 3.64 Ni 2.18 (P 2 O 7 ) 2 , Na 3. Ni 3 (PO 4) 2 ( P 2 O 7), Na 2 CoP 2 O 7, Na 3.64 Co 2.18 (P 2 O 7) 2 and the like.
  • the sodium transition metal phosphate crystal is preferable because of its high capacity and excellent chemical stability.
  • triclinic crystals belonging to the space group P1 or P1 particularly the general formula Na x M y P 2 O z (1.2 ⁇ x ⁇ 2.8,0.95 ⁇ y ⁇ 1.6,6 .5 ⁇ z ⁇ 8) is preferable because of excellent cycle characteristics.
  • Other active material crystals that act as a positive electrode active material include layered sodium transition metal oxide crystals such as NaCrO 2 , Na 0.7 MnO 2 , and NaFe 0.2 Mn 0.4 Ni 0.4 O 2. .
  • the negative electrode active material precursor powder is an oxide equivalent mol%, SnO 0 to 90%, Bi 2 O 3 0 to 90%, TiO 2 0 to 90%, Fe 2 O 3 0 to 90%, Nb 2 O 5 0 ⁇ 90%, SiO 2 + B 2 O 3 + P 2 O 5 5 ⁇ 75%, preferably contains Na 2 O 0 ⁇ 80%.
  • a structure in which Sn ions, Bi ions, Ti ions, Fe ions, or Nb ions, which are active material components, are uniformly dispersed in an oxide matrix containing Si, B, or P is formed. Moreover, it becomes a material excellent in sodium ion conductivity by containing Na 2 O. As a result, it is possible to suppress a volume change when inserting and extracting sodium ions, and it is possible to obtain a negative electrode active material having excellent cycle characteristics.
  • composition of the negative electrode active material precursor powder is limited as described above will be described below.
  • % means “mol%” unless otherwise specified.
  • SnO, Bi 2 O 3 , TiO 2 , Fe 2 O 3 and Nb 2 O 5 are active material components that serve as sites for occluding and releasing alkali ions.
  • the discharge capacity per unit mass of the negative electrode active material is increased, and the charge / discharge efficiency (ratio of the discharge capacity to the charge capacity) at the first charge / discharge is easily improved.
  • release of sodium ion at the time of charging / discharging cannot be relieved, but there exists a tendency for cycling characteristics to fall.
  • the content range of each component is preferably as follows.
  • the SnO content is preferably 0 to 90%, 45 to 85%, 55 to 75%, particularly 60 to 72%.
  • the content of Bi 2 O 3 is preferably 0 to 90%, 10 to 70%, 15 to 65%, particularly 25 to 55%.
  • the content of TiO 2 is preferably 0 to 90%, 5 to 72%, 10 to 68%, 12 to 58%, 15% to 49%, particularly preferably 15 to 39%.
  • the content of Fe 2 O 3 is preferably 0 to 90%, 15 to 85%, 20 to 80%, particularly 25 to 75%.
  • the Nb 2 O 5 content is preferably 0 to 90%, 7 to 79%, 9 to 69%, 11 to 59%, 13 to 49%, and particularly preferably 15 to 39%.
  • SnO + Bi 2 O 3 + TiO 2 + Fe 2 O 3 + Nb 2 O 5 is preferably 0 to 90%, 5 to 85%, particularly preferably 10 to 80%.
  • SiO 2 , B 2 O 3, and P 2 O 5 are network-forming oxides that surround the sodium ion occlusion and release sites in the active material component and have an effect of improving cycle characteristics. Among these, SiO 2 and P 2 O 5 not only improve cycle characteristics, but also have an effect of improving rate characteristics because of excellent sodium ion conductivity.
  • SiO 2 + B 2 O 3 + P 2 O 5 is preferably 5 to 85%, 6 to 79%, 7 to 69%, 8 to 59, 9 to 49%, particularly preferably 10 to 39%.
  • each preferred range of the content of SiO 2, B 2 O 3 and P 2 O 5 is as follows.
  • the content of SiO 2 is preferably 0 to 75%, 5 to 75%, 7 to 60%, 10 to 50%, 12 to 40%, particularly 20 to 35%.
  • the discharge capacity tends to lower.
  • the content of P 2 O 5 is preferably 5 to 75%, 7 to 60%, 10 to 50%, 12 to 40%, particularly 20 to 35%.
  • P 2 content of O 5 is too small, the above effect is difficult to obtain.
  • the content of P 2 O 5 is too large, the discharge capacity tends to decrease and the water resistance tends to decrease.
  • undesirable heterogeneous crystals are generated and the P 2 O 5 network is cut, so that the cycle characteristics are liable to deteriorate.
  • the content of B 2 O 3 is preferably 0 to 75%, 5 to 75%, 7 to 60%, 10 to 50%, 12 to 40%, particularly preferably 20 to 35%. If the B 2 O 3 content is too large, the discharge capacity tends to lower chemical durability tends to decrease.
  • x is too small, alkali ions are easily absorbed in the negative electrode active material during the initial charge, and the initial charge / discharge efficiency tends to be reduced. Further, the alkali ion conductivity is lowered, so that the resistance is increased and the discharge voltage tends to increase.
  • the operating voltage of the battery is determined by the difference between the operating voltage of the positive electrode and the operating voltage of the negative electrode, when the discharge voltage of the negative electrode increases, the operating voltage as a battery tends to decrease.
  • x is too large, a large amount of heterogeneous crystals (for example, Na 4 P 2 O 7 , NaPO 4 ) composed of alkali ions and P 2 O 5 are formed, and the cycle characteristics are likely to deteriorate.
  • the content of the active material component relatively decreases, the discharge capacity tends to decrease.
  • the range of y is 0.25 ⁇ y ⁇ 4, 1 ⁇ y ⁇ 3.8, 1.5 ⁇ y ⁇ 3.6, 2 ⁇ y ⁇ 3.4, especially 3 ⁇ y ⁇ 3.2. Is preferred. If y is too small, alkali ion conductivity tends to be lowered, and cycle characteristics tend to be lowered. On the other hand, if y is too large, the water resistance tends to decrease, and undesirable heterogeneous crystals are likely to be produced when the aqueous electrode paste is produced. As a result, the P 2 O 5 network in the negative electrode active material is cut, and the cycle characteristics are likely to deteriorate.
  • the range of z is preferably 2.5 ⁇ z ⁇ 16, 3 ⁇ z ⁇ 15, 4 ⁇ z ⁇ 14, 6 ⁇ z ⁇ 13, particularly 9 ⁇ z ⁇ 12. If z is too small, Ti is reduced and the valence is lowered, so that the redox reaction associated with charge / discharge hardly occurs. As a result, the number of occluded and released alkali ions decreases, and the capacity of the electricity storage device tends to decrease. On the other hand, if z is too large, a large amount of heterogeneous crystals (eg, Na 4 P 2 O 7 , NaPO 4 ) containing P 2 O 5 are formed, and the cycle characteristics are likely to deteriorate. Moreover, since the content of the active material component relatively decreases, the discharge capacity tends to decrease.
  • heterogeneous crystals eg, Na 4 P 2 O 7 , NaPO 4
  • Examples of the crystal phase represented by the general formula R x TiP y O z include Na 4 TiP 2 O 9 [Na 4 TiO (PO 4 ) 2 ], Na 5 TiP 3 O 12 [Na 5 Ti (PO 4 ) 3 ].
  • These crystal phases can reduce the oxidation-reduction potential of Ti 4 + / Ti 3+ associated with charging / discharging to about 1.2 V (vs. Na / Na + ), and the voltage variation associated with charging / discharging is small and constant. The operating voltage can be easily obtained.
  • Na 3.91 (TiP 2 O 9) preferably Na 4 TiP 2 O 9, Na 5 TiP 3 O 12, Na 5 TiP 3 O 12 having excellent ion conductivity are most preferred.
  • Na 3.91 TiP 2 O 9 and Na 4 TiP 2 O 9 are monoclinic crystals and belong to the space group P21 / c.
  • Na 5 TiP 3 O 12 is a hexagonal crystal and belongs to the space group R32.
  • the negative electrode active material may contain at least one selected from Nb and Ti, and crystals containing O.
  • the crystal is preferable because it has excellent cycle characteristics. Furthermore, it is preferable that the crystal contains Na because charge / discharge efficiency is increased and high discharge capacity can be maintained. In particular, if the crystal is an orthorhombic crystal, a hexagonal crystal, a cubic crystal, or a monoclinic crystal, particularly a monoclinic crystal belonging to the space group P21 / m, it is charged and discharged with a large current. However, it is preferable because the capacity is hardly lowered. Examples of orthorhombic crystals include NaTi 2 O 4 .
  • Examples of the hexagonal crystal include Na 2 TiO 3 , NaTi 8 O 13 , NaTiO 2 , LiNbO 3 , LiNbO 2 , Li 7 NbO 6 , LiNbO 2 , Li 2 Ti 3 O 7 and the like.
  • Examples of cubic crystals include Na 2 TiO 3 , NaNbO 3 , Li 4 Ti 5 O 12 , and Li 3 NbO 4 .
  • Monoclinic crystals include Na 2 Ti 6 O 13 , NaTi 2 O 4 , Na 2 TiO 3 , Na 4 Ti 5 O 12 , Na 2 Ti 4 O 9 , Na 2 Ti 9 O 19 , Na 2 Ti 3.
  • Examples include O 7 , Na 2 Ti 3 O 7 , Li 1.7 Nb 2 O 5 , Li 1.9 Nb 2 O 5 , Li 12 Nb 13 O 33 , LiNb 3 O 8, and the like.
  • Examples of the monoclinic crystal belonging to the space group P21 / m include Na 2 Ti 3 O 7 .
  • the crystal containing at least one selected from Nb and Ti and O preferably further contains at least one selected from B, Si, P and Ge. These components have an effect of facilitating the formation of an amorphous phase together with the active material crystal and improving sodium ion conductivity.
  • the negative electrode active material includes Na metal crystals, alloy crystals containing at least Na (for example, Na—Sn alloy, Na—In alloy), at least one metal crystal selected from Sn, Bi, and Sb, Sn, Bi.
  • an alloy crystal containing at least one selected from Sb for example, Sn—Cu alloy, Bi—Cu alloy, Bi—Zn alloy, Sb—Cu alloy, Sb—Sn alloy, Sb—Si alloy, Sb—In alloy, Sb) -Zn alloy
  • glass containing at least one selected from Sn, Bi and Sb can be used. These are preferable because they have a high capacity and are unlikely to decrease in capacity even when charged and discharged with a large current.
  • the average particle diameter of the active material precursor powder is preferably 0.01 to 15 ⁇ m, 0.05 to 12 ⁇ m, and particularly preferably 0.1 to 10 ⁇ m.
  • the average particle diameter of the active material precursor powder is too small, the cohesive force between the active material precursor powders becomes strong and tends to be inferior in dispersibility when formed into a paste.
  • the internal resistance of the battery increases and the operating voltage tends to decrease.
  • the electrode density tends to decrease and the capacity per unit volume of the battery tends to decrease.
  • the average particle size of the active material precursor powder is too large, sodium ions are difficult to diffuse and the internal resistance tends to increase. Moreover, there exists a tendency to be inferior to the surface smoothness of an electrode.
  • the average particle diameter means D 50 (volume-based average particle diameter), and indicates a value measured by a laser diffraction scattering method.
  • Solid electrolyte powder consists of an oxide material which has sodium ion conductivity, for example.
  • the solid electrolyte powder includes a compound containing at least one selected from Al, Y, Zr, Si and P, Na, and O.
  • examples of such a compound include at least one selected from ⁇ -alumina, ⁇ ′′ -alumina, and NASICON type crystals. These are preferable because they are excellent in sodium ion conductivity.
  • the oxide material containing ⁇ -alumina or ⁇ ′′ -alumina contains Al 2 O 3 65 to 98%, Na 2 O 2 to 20%, MgO + Li 2 O 0.3 to 15% in mol%.
  • the reason for limiting the composition in this way will be described below, and “%” means “mol%” in the following description unless otherwise specified.
  • Al 2 O 3 is ⁇ - alumina and beta "- content .
  • al 2 O 3 is a main component of alumina 65 to 98% is .
  • al 2 O 3 is preferably especially 70 to 95% If the amount is too small, the ionic conductivity tends to decrease, whereas if the amount of Al 2 O 3 is too large, ⁇ -alumina having no ionic conductivity remains and the ionic conductivity tends to decrease.
  • Na 2 O is a component that imparts sodium ion conductivity to the solid electrolyte.
  • the content of Na 2 O is preferably 2 to 20%, 3 to 18%, particularly 4 to 16%.
  • Na 2 O is too small, the effect is difficult to obtain.
  • excess sodium forms a compound that does not contribute to ionic conductivity such as NaAlO 2, so that ionic conductivity tends to decrease.
  • MgO and Li 2 O are components (stabilizers) that stabilize the structure of ⁇ -alumina and ⁇ ′′ -alumina.
  • the content of MgO + Li 2 O is 0.3 to 15%, 0.5 to 10%, In particular, it is preferably 0.8 to 8% If the amount of MgO + Li 2 O is too small, ⁇ -alumina remains in the solid electrolyte and the ionic conductivity tends to decrease, whereas if the amount of MgO + Li 2 O is too large.
  • the MgO or Li 2 O that did not function as a stabilizer remains in the solid electrolyte, and the ionic conductivity tends to decrease.
  • the solid electrolyte powder preferably contains ZrO 2 or Y 2 O 3 in addition to the above components.
  • ZrO 2 and Y 2 O 3 have the effect of suppressing abnormal grain growth of ⁇ -alumina and / or ⁇ ′′ -alumina during firing and improving the adhesion of each particle of ⁇ -alumina and / or ⁇ ′′ -alumina.
  • the content of ZrO 2 is preferably 0 to 15%, 1 to 13%, particularly 2 to 10%.
  • the content of Y 2 O 3 is preferably 0 to 5%, 0.01 to 4%, particularly preferably 0.02 to 3%. If there is too much ZrO 2 or Y 2 O 3, the amount of ⁇ -alumina and / or ⁇ ′′ -alumina produced will decrease, and the ionic conductivity tends to decrease.
  • ⁇ ′′ -alumina includes trigonal (Al 10.35 Mg 0.65 O 16 ) (Na 1.65 O), (Al 8.87 Mg 2.13 O 16 ) (Na 3.13 O), Na 1.67 Mg 0.67 Al 10.33 O 17 , Na 1.49 Li 0.25 Al 10.75 O 17 , Na 1.72 Li 0.3 Al 10.66 O 17 , Na 1.6 Li 0.34 Al 10.66 O 17.
  • ⁇ -alumina examples include hexagonal (Al 10.35 Mg 0.65 O 16 ) (Na 1.65 O), (Al 10.37 Mg 0. 63 O 16 ) (Na 1.63 O), NaAl 11 O 17 , (Al 10.32 Mg 0.68 O 16 ) (Na 1.68 O).
  • a monoclinic or trigonal NASICON type crystal is preferable because of its excellent ion conductivity.
  • crystal represented by the general formula Na s A1 t A2 u O v include Na 3 Zr 2 Si 2 PO 12 , Na 3.2 Zr 1.3 Si 2.2 P 0.8 O 10. 5 , Na 3 Zr 1.6 Ti 0.4 Si 2 PO 12 , Na 3 Hf 2 Si 2 PO 12 , Na 3.4 Zr 0.9 Hf 1.4 Al 0.6 Si 1.2 P 1.8 O 12 , Na 3 Zr 1.7 Nb 0.24 Si 2 PO 12 , Na 3.6 Ti 0.2 Y 0.8 Si 2.8 O 9 , Na 3 Zr 1.88 Y 0.12 Si 2 PO 12 , Na 3.12 Zr 1.88 Y 0.12 Si 2 PO 12 , Na 3.6 Zr 0.13 Yb 1.67 Si 0.11 P 2.9 O 12 and the like.
  • the average particle size of the solid electrolyte powder is 0.01 to 15 ⁇ m, preferably 0.05 to 10 ⁇ m, particularly preferably 0.1 to 5 ⁇ m. If the average particle size of the solid electrolyte powder is too large, the distance required for sodium ion conduction tends to be long, and the ionic conductivity tends to decrease. In addition, the ion conduction path between the active material powder and the solid electrolyte powder tends to decrease. As a result, the discharge capacity tends to decrease. On the other hand, if the average particle size of the solid electrolyte powder is too small, the ion conductivity is likely to be lowered due to the elution of sodium ions and the deterioration due to the reaction with carbon dioxide. Moreover, since voids are easily formed, the electrode density is also likely to decrease. As a result, the discharge capacity tends to decrease.
  • the specific surface area of the solid electrolyte powder (BET specific surface area) is 1.5 ⁇ 200m 2 / g, 2 ⁇ 100m 2 / g, it is particularly preferably 2.5 ⁇ 50m 2 / g. If the specific surface area of the solid electrolyte powder is too small, the distance required for sodium ion conduction tends to be long and the ionic conductivity tends to decrease. In addition, the ion conduction path between the active material powder and the solid electrolyte powder tends to decrease. As a result, the discharge capacity tends to decrease.
  • the specific surface area of the solid electrolyte powder is too large, the ionic conductivity is likely to be lowered due to elution of sodium ions and deterioration due to reaction with carbon dioxide gas. Moreover, since voids are easily formed, the electrode density is likely to decrease. As a result, the discharge capacity tends to decrease.
  • the specific surface area is a value measured by the BET single point method using nitrogen as an adsorbate.
  • the ionic conductivity of the solid electrolyte powder at 25 ° C. is preferably 10 ⁇ 5 S / cm or more, more preferably 10 ⁇ 4 S / cm or more. If the ionic conductivity is too low, it will not function as an ionic conductive material. On the other hand, the upper limit of the ionic conductivity is not particularly limited, but is practically 10 S / cm or less, and further 1 S / cm or less.
  • the solid electrolyte powder can be produced, for example, by firing a raw material powder and subjecting it to a solid phase reaction to obtain a target product, followed by pulverization.
  • a solid electrolyte powder having a desired average particle diameter can be easily obtained.
  • Electrode composite material for sodium ion secondary battery The porosity of the electrode composite material for sodium ion secondary battery is 45% or less, preferably 40% or less, and particularly preferably 35% or less. When the porosity is too high, the adhesion between the active material powder and the solid electrolyte powder becomes insufficient, and the ion conduction path is not sufficiently formed, so that the discharge capacity tends to decrease.
  • the lower limit of the porosity is not particularly limited, but is practically 1% or more.
  • the volume ratio of the active material precursor powder to the solid electrolyte powder is preferably 20:80 to 95: 5, 30:70 to 90:10, particularly 35:65 to 88:12. If the proportion of the active material precursor powder is too small (the proportion of the solid electrolyte powder is too large), the capacity per unit electrode volume tends to decrease, and the energy density of the battery tends to decrease. On the other hand, if the proportion of the active material precursor powder is too large (the proportion of the solid electrolyte powder is too small), the ion conduction path cannot be secured and the ionic conductivity of the electrode mixture is lowered, resulting in a decrease in discharge capacity. Tend to.
  • the active material powder preferably contains an amorphous phase.
  • an amorphous phase is likely to be present at the interface between the active material powder and the solid electrolyte powder, the adhesion between the two is increased, and the porosity is easily decreased.
  • the interface resistance between the active material powder and the solid electrolyte powder tends to decrease.
  • the discharge capacity tends to increase.
  • rapid charge / discharge characteristics are expected to be improved.
  • an amorphous phase intervenes at the interface between the active material powder and the solid electrolyte powder, atomic diffusion between them is suppressed, and chemical decomposition of each powder is suppressed.
  • the electrode mixture for sodium ion secondary batteries of the present invention preferably contains conductive carbon.
  • conductive carbon highly conductive carbon black such as acetylene black or ketjen black, carbon powder such as graphite, carbon fiber, or the like can be used. Of these, acetylene black having a high electron conductivity is preferable.
  • the conductive carbon is preferably contained in the electrode mixture in an amount of 0 to 20% by mass, more preferably 1 to 10% by mass. When there is too much content of conductive carbon, battery capacity will fall easily.
  • the electrode mixture for sodium ion secondary batteries of the present invention is usually in the form of a sheet, and the thickness thereof is preferably 1 to 300 ⁇ m, more preferably 5 to 200 ⁇ m, and further preferably 12 to 90 ⁇ m. .
  • the thickness of the electrode mixture is too small, the capacity of the sodium ion secondary battery itself tends to be small, so that the energy density tends to decrease.
  • the thickness of the electrode mixture is too large, the resistance to electronic conduction increases, and the discharge capacity and operating voltage tend to decrease.
  • the capacity per unit area in the main surface of the electrode mixture for sodium ion secondary batteries of the present invention is preferably 0.03 to 1.5 mAh / cm 2 , and is 0.1 to 0.9 mAh / cm 2 . More preferably. If the capacity per unit area is too small, the battery capacity tends to decrease. On the other hand, when the capacity per unit area is too large, the internal resistance increases and the rapid charge / discharge characteristics tend to be deteriorated.
  • the electrode mixture for sodium ion secondary batteries of the present invention may be composed of a laminate of two or more layers.
  • the number of electrode mixture layers is preferably 7 layers or less, and more preferably 3 layers or less. When the number of layers is too large, the internal resistance between the electrode mixture layers tends to increase.
  • each layer of the electrode mixture composed of the laminate is preferably 3 to 90 ⁇ m, and more preferably 5 to 40 ⁇ m. If the thickness of each layer is too small, it is difficult to form a uniform electrode mixture layer, and as a result, the capacity tends to be difficult to control. On the other hand, if the thickness of each layer is too large, the amount of shrinkage associated with the firing of the electrode mixture precursor increases, cracks are generated, or the ion conductive path with the solid electrolyte sheet is cut off by peeling from the solid electrolyte sheet. It becomes easy and the capacity tends to decrease.
  • each layer of the electrode mixture composed of the laminate may be different.
  • the interface resistance between the solid electrolyte sheet and the electrode mixture can be reduced by relatively increasing the ratio of the solid electrolyte powder in the layer closer to the solid electrolyte sheet.
  • the electron conductivity between the electrode mixture and the current collector layer can be improved. it can.
  • the electrode mixture for sodium ion secondary battery of the present invention comprises: (a) a positive electrode or negative electrode active material precursor powder; and a sodium ion conductive solid electrolyte.
  • a step of slurrying an electrode mixture precursor powder containing powder (b) a step of applying and drying the obtained slurry on a substrate to produce an electrode mixture precursor sheet, and (c) It can manufacture by the method of including the process of baking after pressing an electrode compound-material precursor sheet
  • each process will be described in detail.
  • an active material precursor powder and a raw material powder containing sodium ion conductive solid electrolyte powder are mixed by dry or wet, and then a binder, a plasticizer, a solvent, etc. are added and kneaded to form a slurry.
  • the solvent may be water or an organic solvent such as ethanol or acetone.
  • water when water is used as the solvent, the sodium component is eluted from the raw material powder, the pH of the slurry is increased, and the raw material powder may be aggregated. Therefore, it is preferable to use an organic solvent, and it is particularly preferable to use an anhydrous organic solvent.
  • the obtained slurry is applied on a substrate such as PET (polyethylene terephthalate) and dried to obtain an electrode mixture precursor sheet.
  • the slurry can be applied by a doctor blade or a die coater.
  • the electrode mixture precursor sheet is pressed and then fired to obtain a positive electrode or negative electrode mixture.
  • Examples of the pressing method include a method of pressing from one direction such as a uniaxial press, a method of pressing uniformly from all directions such as an isotropic press, or a roll pressing method passing between two rolls.
  • Specific examples of the isotropic pressure press include a hydrostatic press and a hot isostatic press. Among these, an isotropic pressure press that can efficiently reduce the porosity of the electrode mixture and a uniaxial press that can be easily performed are preferable.
  • the pressing pressure is preferably 3 MPa or more, 10 MPa or more, particularly 15 MPa or more. If the pressing pressure is too low, the adhesion between the active material powder and the solid electrolyte powder becomes insufficient, and the discharge capacity tends to decrease.
  • the upper limit of the pressing pressure is not particularly limited, but is actually 500 MPa, 300 MPa, 100 MPa, or 45 MPa or less.
  • the temperature at the time of a press is 25 degreeC or more, 40 degreeC or more, 60 degreeC or more, especially 70 degreeC or more. If the temperature is too low, the binder does not soften, so the porosity of the electrode mixture is difficult to decrease.
  • the upper limit of the temperature is preferably 200 ° C. or lower, 180 ° C. or lower, 150 ° C. or lower, and 120 ° C. or lower. If the temperature is too high, evaporation of the plasticizer and thermal decomposition of the binder occur, and the sheet shape cannot be maintained.
  • the firing atmosphere examples include an air atmosphere, an inert atmosphere (such as N 2 ), and a reducing atmosphere (such as H 2 , NH 3 , CO, H 2 S, and SiH 4 ).
  • the firing temperature is preferably 400 to 900 ° C, particularly 420 to 800 ° C. If the firing temperature is too low, it becomes difficult for the desired active material crystals to precipitate, or the electrode mixture precursor powder is difficult to sinter sufficiently. On the other hand, if the firing temperature is too high, the precipitated active material crystals may be dissolved.
  • the maximum temperature holding time in firing is preferably 10 to 600 minutes, and more preferably 30 to 120 minutes. If the holding time is too short, the electrode mixture precursor powder is likely to be insufficiently sintered.
  • the active material precursor powders are excessively fused to form coarse particles, so that the specific surface area of the electrode active material is reduced and the charge / discharge capacity is likely to be reduced.
  • an electric heating furnace, a rotary kiln, a microwave heating furnace, a high-frequency heating furnace, or the like can be used.
  • the electrode mixture precursor sheet is laminated and fired. Or you may bake, after apply
  • a laminated body After producing the laminated body sheet
  • the battery for sodium ion secondary batteries it becomes possible to improve the adhesion between the electrode mixture layer and the solid electrolyte sheet.
  • the pressing method, pressure, and temperature of the laminate sheet and laminate are the same as those for the electrode mixture precursor sheet.
  • a sodium ion secondary battery has a positive electrode layer and a negative electrode layer, and a solid electrolyte layer (solid electrolyte sheet) sandwiched therebetween.
  • said electrode compound material is used as a positive electrode layer or a negative electrode layer.
  • the solid electrolyte used for the solid electrolyte layer and the solid electrolyte powder used for the electrode mixture are preferably made of the same material. In this way, the interface resistance between the solid electrolyte layer and the electrode mixture layer is reduced, and the ionic conductivity is easily improved.
  • the capacity ratio between the positive electrode and the negative electrode is preferably 3.0 to 1.0, and more preferably 1.7 to 1.2. If the capacity ratio is too small, metallic sodium tends to precipitate on the negative electrode side and the capacity tends to decrease. On the other hand, if the capacity ratio is too large, the energy density tends to decrease.
  • Table 1 shows Examples 1 to 5 and Comparative Examples 1 and 2.
  • Table 2 shows Examples 6 to 8 and Comparative Example 3.
  • Example 1 Production of solid electrolyte (a-1) Production of solid electrolyte powder Sodium carbonate (Na 2 CO 3 ), sodium hydrogen carbonate (NaHCO 3 ), magnesium oxide (MgO), aluminum oxide (Al 2 O 3 ), oxidation Zirconium (ZrO 2 ) and yttrium oxide (Y 2 O 3 ) are used in mol%, Na 2 O 14.2%, MgO 5.5%, Al 2 O 3 75.4%, ZrO 2 4.7. %, And Y 2 O 3 0.2%, the raw material powder was prepared. The raw material powder was molded by uniaxial pressing at 40 MPa using a ⁇ 20 mm mold and subjected to heat treatment at 1600 ° C. for 30 minutes to obtain ⁇ ′′ -alumina. The obtained ⁇ ′′ -alumina was rapidly dew point ⁇ 40 ° C. Moved to the following atmosphere and stored.
  • ⁇ ′′ -alumina was pulverized with an alumina mortar pestle and passed through a mesh having a mesh opening of 300 ⁇ m. And then pulverized at 300 rpm for 30 minutes, and passed through a mesh with an opening of 20 ⁇ m.After that, by classifying with an air classifier (MDS-1 type, manufactured by Nippon Pneumatic Industry Co., Ltd.), ⁇ ′′ ⁇ A solid electrolyte powder (average particle size 1.8 ⁇ m) made of alumina was obtained. All operations were performed in an atmosphere having a dew point of ⁇ 40 ° C. or lower.
  • MDS-1 type manufactured by Nippon Pneumatic Industry Co., Ltd.
  • A-2) Production of solid electrolyte sheet Sodium carbonate (Na 2 CO 3 ), sodium hydrogen carbonate (NaHCO 3 ), magnesium oxide (MgO), aluminum oxide (Al 2 O 3 ), zirconium oxide (ZrO 2 ), oxidation Using yttrium (Y 2 O 3 ), in mol%, Na 2 O 14.2%, MgO 5.5%, Al 2 O 3 75.4%, ZrO 2 4.7%, Y 2 O 3 0
  • the raw material powder was prepared to have a composition of 2%. Thereafter, the raw material powder was wet-mixed for 4 hours using ethanol as a medium.
  • an acrylic acid ester copolymer (Oricox 1700 manufactured by Kyoeisha Chemical Co., Ltd.) is used as a binder, and benzylbutyl phthalate is used as a plasticizer.
  • the slurry obtained above was applied using a doctor blade with a gap of 350 ⁇ m, and dried at 70 ° C. to obtain a green sheet.
  • the obtained green sheet was pressed at 90 ° C. and 40 MPa for 5 minutes using an isotropic pressure press.
  • the pressed green sheet was fired at 1600 ° C. for 30 minutes to obtain a solid electrolyte sheet made of ⁇ ′′ -alumina having a thickness of 180 ⁇ m.
  • the obtained solid electrolyte sheet was quickly transferred to an environment having a dew point of ⁇ 40 ° C. or less. Stored.
  • the obtained film-like glass was subjected to ball milling using ZrO 2 boulders with a diameter of 20 mm for 5 hours and passed through a resin sieve having an opening of 120 ⁇ m to obtain a coarse glass powder having an average particle size of 3 to 15 ⁇ m.
  • this crude glass powder was subjected to ball milling using ethanol as a grinding aid and ZrO 2 boulder with a diameter of 3 mm for 80 hours, whereby a glass powder having an average particle diameter of 0.7 ⁇ m (positive electrode active material precursor powder) )
  • Electrode mixture layer (positive electrode mixture layer) Mass%, positive electrode active material precursor powder 72%, solid electrolyte powder prepared in (a-1) 25%, acetylene black 3% (positive electrode active material) The volume ratio of the precursor powder to the solid electrolyte powder was weighed to be 76:24), and the mixture was mixed for about 2 hours using an agate mortar and pestle. 20 parts by mass of N-methylpyrrolidone (containing 10% by mass of polypropylene carbonate (manufactured by Sumitomo Seika Co., Ltd.)) is added to 100 parts by mass of the obtained mixed powder, and the mixture is sufficiently stirred using a rotation and revolution mixer. And slurried. All the above operations were performed in an environment with a dew point of ⁇ 40 ° C. or lower.
  • the obtained slurry was applied to one surface of the solid electrolyte sheet prepared in (a-2) with an area of 1 cm 2 and a thickness of 100 ⁇ m, and dried at 70 ° C. for 3 hours. Thereby, the laminated body sheet by which an electrode compound-material precursor layer was formed on the solid electrolyte sheet was obtained.
  • the laminate sheet was isostatically pressed at a pressure of 20 MPa, and then fired at 600 ° C. for 1 hour in a nitrogen gas atmosphere. As a result, a positive electrode mixture layer was formed on one surface of the solid electrolyte sheet.
  • the porosity was determined by binarizing the SEM image of the cross section of the obtained positive electrode mixture layer.
  • Example 2 A test battery was prepared in the same manner as in Example 1 except that the pressing pressure when isostatically pressing the laminate sheet in which the electrode mixture precursor layer was formed on the solid electrolyte sheet was 40 MPa, A charge / discharge test was conducted. The results are shown in Table 1.
  • Example 3 A test battery was produced in the same manner as in Example 1 except that the pressing method of the laminate sheet in which the electrode mixture precursor layer was formed on the solid electrolyte sheet was changed to uniaxial pressing, and the charge / discharge test was performed. It was. The results are shown in Table 1.
  • Example 1 A test battery was prepared in the same manner as in Example 1 except that the laminate sheet in which the electrode mixture precursor layer was formed on the solid electrolyte sheet was fired without isostatic pressing, and the charge / discharge test was performed. went. The results are shown in Table 1.
  • Example 4 A test battery was prepared in the same manner as in Example 1 except that the positive electrode active material precursor powder was changed to the composition shown in Table 1, and a charge / discharge test was performed. The results are shown in Table 1. Moreover, the SEM image of the cross section of a positive electrode compound material layer is shown in FIG. 1, and what binarized the SEM image is shown in FIG.
  • Example 5 A test battery was produced in the same manner as in Example 4 except that the pressing method of the laminate sheet in which the electrode mixture precursor layer was formed on the solid electrolyte sheet was changed to uniaxial pressing, and the charge / discharge test was performed. It was. The results are shown in Table 1.
  • Example 2 A test battery was prepared in the same manner as in Example 4 except that the laminate sheet in which the electrode mixture precursor layer was formed on the solid electrolyte sheet was fired without isostatic pressing, and the charge / discharge test was performed. went. The results are shown in Table 1. Moreover, the SEM image of the cross section of a positive electrode compound material layer is shown in FIG. 3, and what binarized the SEM image is shown in FIG.
  • Example 6 (Examples 6 to 8) (A) Production of solid electrolyte In the same manner as in Example 1, a solid electrolyte powder and a solid electrolyte sheet were produced.
  • Electrode mixture layer (positive electrode mixture layer) Each component was weighed and mixed so as to have the electrode mixture precursor composition shown in Table 2. 20 parts by mass of N-methylpyrrolidone (containing 10% by mass of polypropylene carbonate (manufactured by Sumitomo Seika Co., Ltd.)) is added to 100 parts by mass of the obtained mixed powder, and the mixture is sufficiently stirred using a rotation and revolution mixer. And slurried. All the above operations were performed in an environment with a dew point of ⁇ 40 ° C. or lower.
  • N-methylpyrrolidone containing 10% by mass of polypropylene carbonate (manufactured by Sumitomo Seika Co., Ltd.)
  • the slurry was applied on a solid electrolyte sheet to obtain a laminate sheet in which the electrode mixture precursor layer having the configuration shown in Table 2 was formed.
  • the one close to the solid electrolyte sheet was the first layer, and the coating thickness of each layer was 100 ⁇ m.
  • the laminate sheet was isostatically pressed at a pressure of 20 MPa, and then fired at 500 ° C. for 30 minutes in a nitrogen gas atmosphere. As a result, a positive electrode mixture layer was formed on one surface of the solid electrolyte sheet.
  • the porosity was determined by binarizing the SEM image of the cross section of the obtained positive electrode mixture layer.
  • Example 3 A test battery was prepared in the same manner as in Example 6 except that the laminate sheet in which the electrode mixture precursor layer was formed on the solid electrolyte sheet was fired without being isotropically pressed, and the charge / discharge test was performed. went. The results are shown in Table 1.
  • the porosity is reduced by isostatically pressing or uniaxially pressing the laminate sheet in which the electrode mixture precursor layer is formed on the solid electrolyte sheet. It was confirmed that characteristics such as discharge capacity were improved. In particular, it can be seen that the energy density can be increased by making the electrode mixture layer into a laminate structure.
  • Comparative Example 3 after firing the electrode mixture precursor, the electrode mixture was peeled from the solid electrolyte sheet, and the ion conduction path was in a cut state.

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Abstract

L'invention concerne un mélange d'électrodes pour une batterie secondaire au sodium-ion ayant une capacité de décharge élevée, dans lequel des trajets de conduction ionique sont suffisamment formés entre une poudre de matériau actif et une poudre d'électrolyte solide. Le mélange d'électrodes pour une batterie secondaire au sodium-ion est caractérisé en ce qu'il comprend : un corps fritté d'une poudre précurseur de mélange d'électrodes, qui contient une poudre de précurseur de matériau actif et une poudre d'électrolyte solide ayant une conductivité ionique de sodium; et ayant une porosité de 45 % ou moins.
PCT/JP2018/000400 2017-01-16 2018-01-11 Mélange d'électrodes pour batterie secondaire au sodium-ion et son procédé de fabrication Ceased WO2018131627A1 (fr)

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JPWO2018225494A1 (ja) * 2017-06-09 2020-04-09 日本電気硝子株式会社 全固体ナトリウムイオン二次電池
WO2021054245A1 (fr) * 2019-09-20 2021-03-25 日本電気硝子株式会社 Électrode de cellule auxiliaire et son procédé de fabrication
JPWO2022009811A1 (fr) * 2020-07-09 2022-01-13
CN115425200A (zh) * 2022-09-08 2022-12-02 宁波容百新能源科技股份有限公司 一种钠离子正极材料及其制备方法
WO2024135357A1 (fr) * 2022-12-21 2024-06-27 日本電気硝子株式会社 Élément de stockage d'énergie et batterie secondaire tout solide

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JPWO2018225494A1 (ja) * 2017-06-09 2020-04-09 日本電気硝子株式会社 全固体ナトリウムイオン二次電池
JP7120230B2 (ja) 2017-06-09 2022-08-17 日本電気硝子株式会社 全固体ナトリウムイオン二次電池
WO2021054245A1 (fr) * 2019-09-20 2021-03-25 日本電気硝子株式会社 Électrode de cellule auxiliaire et son procédé de fabrication
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CN114128003A (zh) * 2019-09-20 2022-03-01 日本电气硝子株式会社 二次电池用电极及其制造方法
JP7577917B2 (ja) 2019-09-20 2024-11-06 日本電気硝子株式会社 ナトリウムイオン二次電池及びナトリウムイオン二次電池の製造方法
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WO2022009811A1 (fr) * 2020-07-09 2022-01-13 日本電気硝子株式会社 Électrode à corps fritté, élément de batterie, procédés de fabrication d'électrode à corps fritté et d'élément de batterie, solution de précurseur d'électrolyte solide, précurseur d'électrolyte solide et électrolyte solide
JP7743834B2 (ja) 2020-07-09 2025-09-25 日本電気硝子株式会社 焼結体電極、電池用部材、並びに焼結体電極及び電池用部材の製造方法
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WO2024135357A1 (fr) * 2022-12-21 2024-06-27 日本電気硝子株式会社 Élément de stockage d'énergie et batterie secondaire tout solide

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