Inorganic oxide powder and lithium-ion secondary battery including electrode containing same

Abstract

Provided is a material with which a lithium-ion secondary battery having an excellent discharge capacity retention rate can be obtained. The problem is solved by an inorganic oxide powder containing, in mass % in terms of oxides, 4.0-6.0% of a Li2O component, 3.0-9.0% of an Al2O3 component, 31.0-40.0% of a TiO2 component, and 49.0-57.0% of a P2O5 component, the inorganic oxide powder having a BET specific surface area of 8 m2 / g or more and 35 m2 / g or less and an HF trap capacity of 2.0-9.0.

Description

Lithium-ion secondary battery comprising inorganic oxide powder and electrodes containing the same

[0001] The present invention relates to a lithium-ion secondary battery comprising an inorganic oxide powder and an electrode containing the same.

[0002] Lithium-ion secondary batteries, which have high energy density and can be charged and discharged, are widely used in applications such as power supplies for electric vehicles and mobile phone terminals. Most lithium-ion secondary batteries currently on the market use a liquid electrolyte to achieve high energy density. This electrolyte is typically a non-aqueous electrolyte, which is a solution of lithium salt, an electrolyte component, in an organic solvent. The main structure consists of a separator placed between the positive and negative electrodes, with the aforementioned electrolyte filling the battery. Furthermore, lithium-ion secondary batteries (lithium-ion polymer secondary batteries) that use a polymer compound containing electrolyte components (lithium-ion conductive polymer) as the electrolyte layer instead of liquid electrolyte have also been developed and are commercially available.

[0003] In lithium-ion secondary batteries, as described above, the discharge capacity tends to decrease when repeatedly charged and discharged due to side reactions of the lithium salt, which is an electrolyte component. Therefore, technological development is underway to maintain a high discharge capacity even after repeated charging and discharging.

[0004] For example, Patent Document 1 discloses an electrode for a lithium-ion battery that includes a sulfonic acid compound comprising a sulfonic acid anion represented by a predetermined formula and a Mn cation, which can maintain a higher discharge capacity after repeated charging and discharging of the lithium-ion battery at high temperatures.

[0005] Japanese Patent Publication No. 2023-176985

[0006] However, there is still room for further improvement in lithium-ion secondary batteries as described above, specifically in terms of maintaining discharge capacity (suppressing the decrease in discharge capacity retention rate) after repeated charging and discharging.

[0007] Therefore, the present invention aims to provide a material that makes it possible to obtain a lithium-ion secondary battery with excellent discharge capacity retention.

[0008] To solve the above problems, the inventors diligently conducted research and found that the discharge capacity retention rate of the lithium-ion secondary battery described above correlates with the ability of its electrodes and other components to capture hydrogen fluoride generated in the electrolyte (HF trapping ability). Furthermore, they found that this HF trapping ability is related to the component composition and BET specific surface area of ​​the materials used. Through further investigation, they found that the material contains 4.0-6.0% Li2O, 3.0-9.0% Al2O3, 31.0-40.0% TiO2, and 49.0-57.0% P2O5 in terms of oxide mass percentage, and has a BET specific surface area of ​​8 m². 2 / g or more 35m 2 We discovered that by incorporating inorganic oxide powder, which has a concentration of less than / g and an HF trapping capacity of 2.0 to 9.0, into the electrode together with the electrode active material, the inorganic oxide powder can capture hydrogen fluoride generated in the electrolyte when a lithium-ion secondary battery equipped with such electrodes is repeatedly charged and discharged, thereby maintaining a high discharge capacity retention rate, and thus completed the present invention.

[0009] In other words, the present invention includes the following embodiments <1> to <13>. <1> Containing, by mass%, in terms of oxide equivalent, 4.0 to 6.0% Li2O component, 3.0 to 9.0% Al2O3 component, 31.0 to 40.0% TiO2 component, and 49.0 to 57.0% P2O5 component, with a BET specific surface area of ​​8 m². 2 / g or more 35m 2 <1> An inorganic oxide powder having a density of 1 / g or less and an HF trapping capacity of 2.0 or more and 9.0 or less. <2> The inorganic oxide powder according to <1>, wherein the product of the BET specific surface area and the content of the Al2O3 component (BET × Al2O3) is 30 or more and 300 or less, more preferably 45 or more and 260 or less. <3> The average particle size (D) of the inorganic oxide powder. 50The ratio of the BET specific surface area to the average particle diameter (BET / average particle diameter) for <1> or <2> is 10 or more, and the inorganic oxide powder according to <1> or <2>. <4> The inorganic oxide powder according to any one of <1> to <3>, wherein the content of the Al2O3 component is 5.0% or more, and the content of the TiO2 component is 33.0% or more. <5> The inorganic oxide powder according to any one of <1> to <4>, wherein the content of the Al2O3 component is 5.0% or more, and the sum of the contents of the Li2O component, the Al2O3 component, and the TiO2 component (Li2O + Al2O3 + TiO2) is 45.5% or more. <6> The inorganic oxide powder according to any one of <1> to <5>, which is a glass powder. <7> The inorganic oxide powder according to <6>, wherein the lithium ion conductivity at 25 °C is 1.0 × 10 -7 S / cm or more. <8> The inorganic oxide powder according to any one of <1> to <5>, which is a glass-ceramics powder or a ceramics powder containing LATP crystals. <9> The inorganic oxide powder according to <8>, wherein the LATP crystal is the main crystal phase. <10> The lithium ion conductivity at 25 °C is 1.0 × 10 -5 S / cm or more, more preferably 1.0 × 10 -4 S / cm or more. The inorganic oxide powder according to <8> or <9>. <11> The average particle diameter (D 50 ) is 0.1 μm or more and 2.0 μm or less, more preferably 0.2 μm or more and 1.0 μm or less. The inorganic oxide powder according to any one of <1> to <10>. <12> An electrode containing the inorganic oxide powder according to any one of <1> to <11>, more preferably a positive electrode, and an electrolyte layer containing a lithium salt containing fluorine as an electrolyte component. A lithium ion secondary battery. <13> The electrode, more preferably the positive electrode, and a non-aqueous electrolyte containing LiPF6 as an electrolyte component, and the lithium ion secondary battery according to <12>, wherein the discharge capacity retention rate at 300 cycles is more than 70%.

[0010] According to the present invention, it is possible to provide an inorganic oxide powder capable of obtaining a lithium ion secondary battery having an excellent discharge capacity retention rate, and further, a lithium ion secondary battery containing this in an electrode and having an excellent discharge capacity retention rate can be provided.

[0011] This graph shows the relationship between the BET / average particle size and HF trapping capacity of the inorganic oxide powders of the examples and comparative examples. This graph shows the relationship between the BET × Al2O3 and HF trapping capacity of the inorganic oxide powders of the examples and comparative examples. This graph shows the relationship between the HF trapping capacity of the inorganic oxide powders of the examples and comparative examples and the discharge capacity retention rate at 300 cycles of a lithium-ion secondary battery equipped with a positive electrode containing the inorganic oxide powder. This graph shows the relationship between the number of cycles and the discharge capacity retention rate of a lithium-ion secondary battery equipped with a positive electrode containing the inorganic oxide powder of Example 2 or Comparative Example 3.

[0012] The present invention will now be described. The present invention contains, in terms of mass percent on an oxide basis, 4.0 to 6.0% Li2O component, 3.0 to 9.0% Al2O3 component, 31.0 to 40.0% TiO2 component, and 49.0 to 57.0% P2O5 component, and has a BET specific surface area of ​​8 m². 2 / g or more 35m 2 The present invention comprises an inorganic oxide powder having a density of 2.0 or less per gram and an HF trapping capacity of 9.0 or more (hereinafter, this may also be referred to as "the inorganic oxide powder of the present invention"), an electrode containing the inorganic oxide powder, and an electrolyte layer containing a lithium salt containing fluorine as an electrolyte component.

[0013] First, the components (essential components, optional components), their form, physical properties, etc., that constitute the inorganic oxide powder of the present invention will be described in detail.

[0014] The content of each component in the inorganic oxide powder of the present invention is expressed in mass % (wt%) in terms of oxide unless otherwise specified (hereinafter, when simply % is mentioned regarding the content of a component, it means mass % in terms of oxide unless otherwise specified). The content expressed as "mass % in terms of oxide" is determined by analyzing the inorganic oxide powder of the present invention by performing ICP emission spectroscopy (inductively coupled plasma emission spectroscopy) for the Li component and XRF analysis (X-ray fluorescence analysis) for the other components. Based on the analysis values, the total mass assuming all components are oxides is set to 100% by mass, and the oxide content of each component in the inorganic oxide powder of the present invention is expressed in mass %.

[0015] The Li2O component is an essential component for imparting lithium ion conductivity to the inorganic oxide powder of the present invention. It also becomes a constituent component of LATP crystals. Therefore, the Li2O content is set to 4.0 to 6.0%. From the viewpoint of lithium ion conductivity and LATP crystal formation (glass ceramic powder or ceramic powder), the lower limit is more preferably 4.3% or more, even more preferably 4.4% or more, and even more preferably 4.5% or more. The upper limit is more preferably 5.8% or less, even more preferably 5.5% or less, even more preferably 5.2% or less, and even more preferably 5.0% or less, from the viewpoint of easily suppressing the generation of by-products during crystallization and easily achieving high HF trapping ability. Furthermore, in cases such as when using glass powder, this upper limit may be set to 5.1% or less, or even 4.6% or less, in order to easily suppress the formation of heterogeneous crystals.

[0016] The Al₂O₃ component is an essential component necessary for the inorganic oxide powder of the present invention to have lithium ion conductivity and a high HF trapping ability. It also becomes a constituent component of the LATP crystal. Therefore, the content of the Al₂O₃ component is set to 3.0 to 9.0%. From the viewpoint of the above effects, this lower limit is more preferably 4.0% or more, further preferably 5.0% or more, further preferably 6.0% or more, further preferably 6.5% or more, and further preferably 7.0% or more. The upper limit is more preferably 8.8% or less, further preferably 8.7% or less, and further preferably 8.5% or less, from the same viewpoint and the ease of forming the LATP crystal (glass-ceramics powder or ceramics powder). In the case of making glass powder, from the viewpoints of glass formation, stability of glass alone, and grindability, the above-mentioned lower limit may be 6.8% or more, further 7.5% or more, further 8.0% or more, and further 8.4% or more.

[0017] The TiO₂ component is also an essential component necessary for the inorganic oxide powder of the present invention to have lithium ion conductivity and a high HF trapping ability. It also becomes a constituent component of the LATP crystal. Therefore, the content of the TiO₂ component is set to 31.0 to 40.0%. From the viewpoint of the above effects, this lower limit is more preferably 33.0% or more, and further preferably 34.0% or more. The upper limit is more preferably 38.0% or less, further preferably 37.0% or less, and further preferably 35.0% or less, because it is easy to suppress the generation of by-products during crystallization and the resulting product is likely to have a high HF trapping ability.

[0018] The P2O5 component is also an essential component necessary for the inorganic oxide powder of the present invention to have lithium ion conductivity and high HF trapping capacity. It also becomes a component of LATP crystals. For this reason, the P2O5 content is set to 49.0 to 57.0%. From the viewpoint of the above effects, the lower limit is more preferably 49.5% or more, and even more preferably 50.0% or more. For similar reasons, as well as to suppress the generation of by-products during crystallization, and for ease of pulverization, the upper limit is more preferably 56.5% or less, even more preferably 56.0% or less, even more preferably 55.5% or less, even more preferably 55.0% or less, even more preferably 54.5% or less, even more preferably 54.0% or less, even more preferably 53.5% or less, even more preferably 53.0% or less, even more preferably 52.5% or less, even more preferably 52.0% or less, even more preferably 51.5% or less, and even more preferably 51.0% or less.

[0019] Furthermore, in order to more easily exhibit the effects of the present invention, it is preferable that the inorganic oxide powder of the present invention has an Al2O3 component content of 5.0% or more and a TiO2 component content of 33.0% or more. Moreover, it is also preferable that the Al2O3 component content be 6.0% or more and the TiO2 component content be 34.0% or more. And the Al2O3 component content may be 6.5% or more. For similar reasons, it is preferable that the inorganic oxide powder of the present invention has an Al2O3 component content of 5.0% or more and that the sum of the content of the Li2O component, Al2O3 component, and TiO2 component (total of Li2O component content, Al2O3 component content, and TiO2 component content, Li2O + Al2O3 + TiO2) be 45.5% or more. Furthermore, the lower limit of the sum of these contents is more preferably 46.0% or more, and even more preferably 46.5% or more. The lower limit of the content of this Al2O3 component may also be within the above range (for example, 6.0% or more, and even more preferably 6.5% or more). The upper limit of the sum of the above contents may be, for example, 51.0% or less, or 50.0% or less.

[0020] The inorganic oxide powder of the present invention may further contain, as optional components, one or more selected from the group consisting of SiO2 component, GeO2 component, ZrO2 component, SnO2 component, B2O3 component, Y2O3 component, Sc2O3 component, ZnO component, Na2O component, K2O component, and transition metal oxides such as Co, Ni, Mn, and Fe. However, any of these optional components may also be in an embodiment that does not substantially contain them (a configuration consisting of the above-described essential components). Hereinafter, this optional component will be described.

[0021] The SiO2 component is an optional component that facilitates glass formation when the inorganic oxide powder of the present invention is made into glass powder or glass-ceramics powder. And when it is made into glass-ceramics powder or ceramics powder, it also becomes a constituent component of LATP crystal, substitutes for the P site of the PO4 skeleton in the LATP crystal, causes distortion of the skeleton, enhances lithium ion conductivity, and further enhances the HF trapping ability. In addition, this SiO2 component can also enhance the mechanical strength of the inorganic oxide powder of the present invention. The content of the SiO2 component is preferably 5.0% or less, more preferably 3.0% or less. The lower limit may be more than 0%, may be 0.1% or more, or may be 0.2% or more.

[0022] The GeO2 component is an optional component that facilitates crystal formation when the inorganic oxide powder of the present invention is made into glass-ceramics powder or ceramics powder. And it also becomes a constituent component of LATP crystal, substitutes for the Ti site in the LATP crystal, and can enhance lithium ion conductivity by increasing the lithium ion content in the LATP crystal. The content of the GeO2 component is preferably 5.0% or less, more preferably 3.0% or less, and still more preferably 1.0% or less.

[0023] The ZrO2 component is an optional component that can contribute to improving the chemical durability of the inorganic oxide powder of the present invention. In addition, this ZrO2 component can also enhance the water resistance of the inorganic oxide powder of the present invention. The content of the ZrO2 component is preferably 5.0% or less, more preferably 3.0% or less, still more preferably 1.0% or less, and still more preferably 0.5% or less.

[0024] The SnO2 component is also an optional component that facilitates crystal formation when the inorganic oxide powder of the present invention is a glass ceramic powder or a ceramic powder. The SnO2 content is preferably 5.0% or less, more preferably 3.0% or less, and even more preferably 1.0% or less.

[0025] The B2O3 component is also an optional component that facilitates glass formation when the inorganic oxide powder of the present invention is made into glass powder or glass ceramic powder. Furthermore, this B2O3 component can be substituted for a portion of the Al2O3 component and is also a component that can adjust the lithium ion conductivity of the inorganic oxide powder of the present invention. The content of the B2O3 component is preferably 5.0% or less, more preferably 3.0% or less, and even more preferably 1.0% or less.

[0026] The Sc2O3 and Y2O3 components can also be substituted for a portion of the Al2O3 component and are optional components that can adjust the lithium ion conductivity of the inorganic oxide powder of the present invention. The content of each of these components is preferably 5.0% or less, more preferably 3.0% or less, and even more preferably 1.0% or less.

[0027] The ZnO component can be substituted for a portion of the TiO2 component and is an optional component that can adjust the lithium ion conductivity of the inorganic oxide powder of the present invention. The ZnO content is preferably 5.0% or less, more preferably 3.0% or less, and even more preferably 1.0% or less.

[0028] The Na2O and K2O components are also optional components that can adjust the lithium ion conductivity of the inorganic oxide powder of the present invention. The content of each of these components is preferably 5.0% or less, more preferably 3.0% or less, even more preferably 1.0% or less, and even more preferably 0.5% or less.

[0029] Transition metals such as Co, Ni, Mn, and Fe are optional components that can suppress the elution of transition metals and other elements contained in the electrode active material (especially the positive electrode active material) into the electrolyte. The total content of these transition metal oxides is preferably 5.0% or less, more preferably 3.0% or less, even more preferably 1.0% or less, and even more preferably 0.5% or less.

[0030] Furthermore, it is preferable that the inorganic oxide powder of the present invention contains as little sulfur (S) as possible (for example, less than 0.5%, and even less than 0.1%), and more preferably no sulfur at all. This is because reducing the S component reduces the possibility of generating harmful gases such as hydrogen sulfide in lithium-ion secondary batteries and the like that equipped with electrodes containing the inorganic oxide powder of the present invention. Similarly, it is preferable to reduce the content of arsenic (As), antimony (Sb), and lead (Pb) as much as possible, and more preferably no sulfur at all, because they are harmful substances. Furthermore, it is preferable to reduce the content of bismuth (Bi) and tellurium (Te) as much as possible, and more preferably no sulfur at all.

[0031] Furthermore, the inorganic oxide powder of the present invention having the above-described component composition may be a glass powder (amorphous powder) obtained from a glass melt obtained by melting the raw material at a predetermined temperature, or it may be a glass ceramic powder obtained by crystallizing the raw material after vitrification by heat treatment or the like. This glass ceramic powder may also be obtained by heat treatment or the like of the glass powder described above. Furthermore, it may be a ceramic powder obtained by sintering the raw material or the like. When the inorganic oxide powder of the present invention is a glass ceramic powder or a ceramic powder, in either case it contains LATP crystals, and it is more preferable that these LATP crystals are the main crystalline phase (more than 50% by mass, preferably 70% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 99% by mass or more of the total crystalline phase is LATP crystals). However, embodiments may also include crystals other than LATP crystals (for example, other NASICON-type lithium-ion conductive crystals, lithium-ion conductive crystals of other structures such as LISICON-type, perovskite-type, garnet-type, etc., and other by-product crystals). Here, "LATP crystal" refers to Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 This is a NASICON-type lithium-ion conductive oxide crystal represented by the compositional formula (0 ≤ x ≤ 0.4, 0 ≤ y ≤ 0.6). In this formula, from the viewpoint of lithium-ion conductivity, the lower limit of X is preferably greater than 0, more preferably 0.05 or higher, even more preferably 0.08 or higher, and still more preferably 0.10 or higher. The upper limit is preferably 0.35 or lower, and more preferably 0.30 or lower. From a similar viewpoint, the lower limit of Y is preferably greater than 0, more preferably 0.025 or higher, even more preferably 0.04 or higher, and still more preferably 0.06 or higher. The upper limit is preferably 0.50 or lower, more preferably 0.40 or lower, and still more preferably 0.30 or lower.

[0032] Furthermore, the glass powder described above consists of an amorphous phase (non-crystalline phase) and substantially contains no crystalline phase. In addition, the glass ceramic powder described above contains a crystalline phase (for example, LATP crystals as the main crystalline phase and other by-product crystalline phases) and an amorphous phase (non-crystalline phase). In other words, it is a mixture of ceramics and glass. Moreover, the ceramic powder described above consists of a crystalline phase (for example, LATP crystals as the main crystalline phase and other by-product crystalline phases) and substantially contains no amorphous phase (non-crystalline phase).

[0033] <BET Specific Surface Area> The inorganic oxide powder of the present invention has the above-described component composition and form, and its BET specific surface area is 8 m². 2 / g or more 35m 2 The amount is less than / g. This results in a high HF trapping capacity, and when incorporated into the electrodes of a specified lithium-ion secondary battery, it can maintain a high discharge capacity retention rate. This lower limit is set at 9m because it makes it easier to increase the HF trapping capacity and keep the average particle size small. 2 It is more preferable to be 10 m or more per g. 2 It is even more preferable that it be 11m or more / g. 2 It is even more preferable that it be 12m or more / g. 2 It is even more preferable that it be 15m or more / g. 2 It is even more preferable that the amount is 32 m / g or more. The upper limit is 32 m from the viewpoint of wettability with the electrolyte and pulverizability of the powder particles. 2 It is more preferable that the amount be less than or equal to 31m 2 It is even more preferable that it be less than or equal to / g, and 30m 2 It is even more preferable that it be less than or equal to / g, and 27m 2 It is even more preferable that the BET specific surface area is less than or equal to / g. This can be adjusted by the composition, firing conditions, and conditions during crushing and sizing. Here, this BET specific surface area means the average value of two measurements taken using the BET single-point method with a MOUNTECH Macsorb HM-1201 fully automatic specific surface area meter.

[0034] Furthermore, in the inorganic oxide powder of the present invention, the effects of the present invention are more easily exhibited, and this BET specific surface area (m²) 2 It is more preferable that the product of (BET × Al2O3) between (g) and the content of the aforementioned Al2O3 component (mass %) in terms of oxide is 30 or more and 300 or less. The lower limit is more preferably 45 or more, more preferably 60 or more, more preferably 75 or more, more preferably 90 or more, more preferably 130 or more, and more preferably 150 or more. The upper limit is more preferably 280 or less, and more preferably 260 or less.

[0035] <HF Trap Ability> The inorganic oxide powder of the present invention has the above-described component composition, form, BET specific surface area, etc., and therefore its HF trap ability (ability to capture hydrogen fluoride) is 2.0 or more and 9.0 or less. As a result, when the inorganic oxide powder of the present invention is included in the electrodes of a predetermined lithium-ion secondary battery, it is possible to efficiently capture hydrogen fluoride that may be generated in the electrolyte layer (generated mainly by a side reaction between a lithium salt containing fluorine and a trace amount of water contained in the electrolyte layer (for example, a side reaction such as LiPF6 + H2O → LiF + 2HF + POF3)), thereby reducing the concentration of hydrogen fluoride contained in the lithium-ion secondary battery, and thus maintaining a high discharge capacity retention rate even after repeated charging and discharging. The lower limit is more preferably 2.3 or more, even more preferably 3.0 or more, even more preferably 4.0 or more, even more preferably 5.0 or more, even more preferably 6.0 or more, even more preferably 6.5 or more, and even more preferably 7.0 or more. The upper limit may be, for example, 8.0 or less. This HF trapping capacity is measured and calculated using the following procedure.

[0036] 60 g of an electrolyte containing 1 ppm to 40 ppm of HF (hydrogen fluoride) and 20 ppm or less of water (electrolyte component: 1 mol / L LiPF6, solvent: ethylene carbonate:ethyl methyl carbonate = 3:7, where "ppm" is the volume ratio of the amount of the component to the total volume of the electrolyte) is mixed with 2 g of the inorganic oxide powder of the present invention (pre-dried under vacuum at 160°C for 24 hours using a glass tube oven (manufactured by Nippon Buch Co., Ltd., B-585)) and sealed with aluminum laminate. After storing this in a constant temperature bath at 60°C for one week, the electrolyte is extracted to obtain a sample for HF concentration measurement. This sample is diluted with pure water and neutralized by titration using a 0.01 mol / L sodium hydroxide solution in an automatic titrator. Then, assuming that all the acid contained in the electrolyte is HF, the HF trapping capacity is calculated from the HF concentration using the following formula.

[0037] HF concentration = (D - B) × K × F × M × 1000 / S D: Titration volume of sodium hydroxide solution to the endpoint (mL) B: Titration volume of blank sodium hydroxide solution (mL) K: Molecular weight of HF (20.0063) F: Sodium hydroxide solution factor M: Sodium hydroxide concentration (0.01 mol / L) S: Sample volume (g) HF trapping capacity = 100 × (1 / HF concentration)

[0038] <Lithium Ion Conductivity> The inorganic oxide powder of the present invention is a lithium ion conductive inorganic oxide powder (lithium ion conductive inorganic material), and is not limited thereto, but its lithium ion conductivity at 25°C is 1.0 × 10⁻⁶ -7 Preferably, the lithium ion conductivity is (1.0E-07) S / cm or higher, and if the inorganic oxide powder of the present invention is a glass ceramic powder or ceramic powder containing LATP crystals, its lithium ion conductivity at 25°C is 1.0 × 10⁻⁶. -5 It is more preferable that the ratio is (1.0E-05) S / cm or higher, and 1.0 × 10 -4It is even more preferable that the conductivity is (1.0E-04) S / cm or higher. Here, this lithium ion conductivity is calculated by forming a gold electrode as a blocking electrode on the object to be measured using a magnetron sputtering apparatus, and then measuring the impedance using an electrochemical evaluation apparatus at 25°C under the conditions of a frequency of 0.1 Hz to 7 MHz, an amplitude voltage of 10 mV, and an open-circuit voltage. In this measurement, the object to be measured is a solid material before powdering (before pulverization) on which a gold electrode can be formed on the surface.

[0039] <Average particle size> The inorganic oxide powder of the present invention has an average particle size (D 50 A particle size of 0.1 μm or more and 2.0 μm or less is preferable from the viewpoint of the effects of the present invention and ease of use in electrodes. The lower limit may be 0.2 μm or more, and the upper limit may be 1.5 μm or less, further 1.0 μm or less, further 0.7 μm or less, further 0.6 μm or less, further 0.5 μm or less, and further 0.4 μm or less. This can be adjusted by conditions during grinding and sizing. Here, this "average particle size (D)" is 50 ) refers to the average particle diameter based on volume (50% diameter of the volume integrated distribution (D) measured by a laser diffraction / scattering particle size distribution analyzer. 50 ))

[0040] Furthermore, in the inorganic oxide powder of the present invention, this average particle size (D 50 The aforementioned BET specific surface area (m²) relative to μm. 2It is preferable that the ratio of (BET / average particle size) ( / g) be 10 or more, and more preferably 25 or more. This is because the particle shape of the powder becomes more uneven or porous, which increases the contact area with the electrolyte, and thus increases the HF trapping capacity. In particular, for glass ceramic powder or ceramic powder, it is preferable that the above ratio be 40 or more. The lower limit is more preferably 45 or more, and even more preferably 50 or more. This ratio can be adjusted by adjusting the crystallization and firing conditions to reduce the crystal size of LATP crystals, etc., making it easier to pulverize into such a shape, or by reducing the amount of media relative to the pulverizing material and adopting pulverizing conditions that increase the BET specific surface area without making the particle size too small. The upper limit is not particularly limited, but for example it may be 200 or less, or 150 or less.

[0041] The present invention provides a method for producing inorganic oxide powders using general methods in the production of inorganic materials, such as calcination, melting, vitrification, crystallization, and sintering, or modified methods thereof. While not limited to these methods, when producing glass powder, examples include melting the raw materials at a predetermined temperature (for example, 1000°C or higher, and even 1200°C to 1600°C, with a particularly favorable rapid heating rate of 100°C / min or higher), casting the resulting glass melt onto a metal casting plate or dropping it into flowing water to obtain glass particles, and then further crushing, finely grinding, and pulverizing through a classification device to produce glass powder. Furthermore, when producing glass ceramic powder, an example is to vitrify the raw materials (melt and rapidly cool), then crystallize them by heat treatment (for example, to 900°C or higher, or even 900°C to 1200°C, with a heating rate of 10°C / min or higher being particularly preferable), cool them (cooling at a cooling rate of 10°C / min or higher is particularly preferable) to obtain glass ceramic particles, and then further crush them, finely grind them, and pulverize them through a classification device to produce glass ceramic powder. Furthermore, when producing ceramic powder, an example is to mix and mold the raw materials, perform solid-phase reaction sintering (for example, to 700°C to 1300°C, with a heating rate of 30°C / min or higher for calcination and 10°C / min or higher for final calcination), cool them (cooling at a cooling rate of 10°C / min or higher is particularly preferable) to obtain a ceramic body, and then further crush them, finely grind them, and pulverize them through a classification device to produce ceramic powder. These methods share a common characteristic: by appropriately adjusting the homogeneity of heating and cooling, the heating rate, the heating temperature and time, the cooling rate, the cooling temperature and time, the grinding conditions (material, quantity, and diameter of the media, the type and quantity of solvent in the case of wet grinding, grinding time, etc.), and the grinding equipment, the inorganic oxide powder of the present invention can be obtained.

[0042] <Lithium-ion secondary battery> Next, a lithium-ion secondary battery comprising an electrode containing the inorganic oxide powder of the present invention and an electrolyte layer containing a lithium salt containing fluorine as an electrolyte component will be described in detail.

[0043] As described above, this lithium-ion secondary battery comprises an electrode containing the inorganic oxide powder of the present invention (an electrode containing the inorganic oxide powder of the present invention together with an electrode active material), and an electrolyte layer containing a fluorine-containing lithium salt as an electrolyte component (a non-aqueous electrolyte or a lithium-ion conductive polymer electrolyte), and has excellent discharge capacity retention (high discharge capacity is maintained when repeatedly charged and discharged, for example, a discharge capacity retention rate of more than 70% after 300 cycles under predetermined conditions). For example, the inorganic oxide powder of the present invention, a positive electrode material (positive electrode active material) or a negative electrode material (negative electrode active material), and a conductive additive, binder, etc. as needed are mixed and molded to form an electrode (positive electrode or negative electrode), and the electrodes (positive electrode and negative electrode) containing this electrode are combined with a non-aqueous electrolyte in which a fluorine-containing lithium salt is dissolved as an electrolyte component in an aprotic organic solvent, and a separator (placed between the positive electrode and the negative electrode) to form the above-mentioned lithium-ion secondary battery. Furthermore, at least a portion of the surface of the positive electrode material or the negative electrode material may be coated with the inorganic oxide powder of the present invention and used to form the electrode, or both the above mixing and this coating may be performed. The inorganic oxide powder of the present invention may be contained in only one of the positive electrode or the negative electrode, or in both of them, but it is more preferable that at least the positive electrode contains the inorganic oxide powder of the present invention, as this makes it easier to exhibit the effects of the present invention. In addition, when a lithium-ion conductive polymer electrolyte is used as the electrolyte layer, the inorganic oxide powder of the present invention may also be blended into this polymer electrolyte. Normally, including materials other than the electrode active material in the electrodes of a lithium-ion secondary battery tends to lead to a decrease in discharge capacity and discharge capacity retention rate, but one of the major features of the inorganic oxide powder of the present invention is that by including it together with the electrode active material in the electrodes of a lithium-ion secondary battery, it is possible to maintain the discharge capacity (suppress the decrease in discharge capacity retention rate).

[0044] As the positive electrode active material for the positive electrode material, a transition metal compound capable of intercalating and releasing lithium can be used. For example, a transition metal oxide containing at least one selected from the group consisting of manganese, cobalt, nickel, vanadium, niobium, molybdenum, iron, and titanium (specifically, LiCoO2, etc.) can be used. As the negative electrode active material for the negative electrode material, examples include metallic lithium, lithium-aluminum alloys, lithium-indium alloys and other alloys capable of intercalating and releasing lithium, transition metal oxides such as titanium and vanadium, and carbon-based materials such as graphite (specifically, artificial graphite, etc.). Furthermore, as a conductive additive, carbon-based materials such as acetylene black can be used. Furthermore, as a binder, examples include fluororesins such as PVDF (polyvinylidene fluoride) and rubber materials such as SBR (styrene-butadiene rubber). In addition, thickeners such as CMC (carboxymethylcellulose sodium) can also be used.

[0045] Furthermore, a non-aqueous electrolyte is an electrolyte in which an electrolyte component containing a fluorine-containing lithium salt is dissolved in a liquid non-aqueous solvent. Examples of this liquid non-aqueous solvent include aprotic organic solvents (for example, mixed solvents of cyclic carbonates and / or linear carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, fluoroethylene carbonate, ethyl methyl carbonate, diethyl carbonate, and dimethyl carbonate). Examples of the electrolyte component include lithium salts such as lithium hexafluoride phosphate (LiPF6) and lithium bisfluorosulfonimide (LiFSI). Furthermore, examples of lithium-ion conductive polymer electrolytes include those in which an electrolyte component containing a fluorine-containing lithium salt is impregnated into a polymer compound (such as a polymer gel, for example, polyvinylidene fluorolide or polyacrylonitrile). In addition, a liquid non-aqueous solvent as described above may also be impregnated. Furthermore, a lithium-ion conductive inorganic material may be further included. Furthermore, it is also possible to use this non-aqueous electrolyte or lithium-ion conductive polymer electrolyte in combination with other electrolyte components that do not contain fluorine.

[0046] <Discharge Capacity Retention Rate> As described above, the lithium-ion secondary battery comprising the electrode containing the inorganic oxide powder of the present invention and the electrolyte layer containing a lithium salt containing fluorine as an electrolyte component exhibits excellent discharge capacity retention rate. For example, in the case of a lithium-ion secondary battery comprising the electrode (especially the positive electrode) containing the inorganic oxide powder of the present invention and a non-aqueous electrolyte containing LiPF6 as an electrolyte component, the discharge capacity retention rate after 300 cycles can be set to more than 70%. In other words, the discharge capacity after 300 cycles of repeated charging and discharging (discharge capacity at the 300th cycle) can be maintained at more than 70% compared to the discharge capacity at the first cycle, which is set to 100%. Furthermore, this discharge capacity retention rate can be set to 72% or more, even 75% or more, even 78% or more, and even 80% or more.

[0047] The discharge capacity retention rate over 300 cycles can be measured as follows. Specifically, first, a positive electrode is prepared by coating an Al foil, which is the positive electrode current collector, with a positive electrode mixture containing 0 to 10 wt% of the inorganic oxide powder of the present invention and drying it. A negative electrode is prepared by coating a Cu foil, which is the negative electrode current collector, with a negative electrode mixture containing 0 to 10 wt% of the inorganic oxide powder of the present invention and drying it (the inorganic oxide powder of the present invention is mixed into either the positive electrode mixture or the negative electrode mixture, or both, and it is particularly preferable to mix it into the positive electrode mixture). A lithium-ion secondary battery is then prepared by combining a non-aqueous electrolyte solution with LiPF6 as the electrolyte component, the above-mentioned positive and negative electrodes, and a separator. Then, using a charge / discharge device, known chemical treatment and known aging are performed in this order, and the following cycle test is conducted to confirm the discharge capacity over a predetermined number of cycles, and the retention rate of the discharge capacity (mAh / g) at 300 cycles relative to the discharge capacity (mAh / g) at 1 cycle is calculated. Cycle test: A test in which CC-CV charging (1.0C, 4.4V - 0.05C cutoff, 25℃) and CC discharge (1.0C, 3.0V cutoff, 25℃) are repeated as one cycle.

[0048] The embodiments described above are merely examples to facilitate understanding of the present invention and do not limit it. In other words, the components and the like described above can be changed or improved without departing from the spirit of the present invention, and of course, the present invention includes equivalents thereof.

[0049] The following describes embodiments of the present invention, but the present invention is not limited to the following embodiments, and various modifications are possible within the technical concept of the present invention.

[0050] We fabricated various inorganic oxide powders with lithium-ion conductivity and evaluated them, as well as lithium-ion secondary batteries equipped with electrodes containing these powders.

[0051] <Preparation of Lithium-Ion Conductive Inorganic Oxide Powder> LiCO3, H3PO4, TiO2, and Al(PO3)3, and SiO2 as needed, were used as raw materials. The final product was weighed and uniformly mixed so that the composition was as shown in Table 1 below, expressed in mass percent on an oxide basis. The mixture was then placed in a platinum pot and rapidly heated (heating rate of 200-800°C / min), and heated and melted in an electric furnace at 1500°C for 4 hours while stirring. The resulting glass melt was then rapidly cooled by dropping it into running water to obtain flake-like glass. This flake-like glass was quickly recovered from the water, spread on a flat plate, and dried in a constant temperature bath at 100°C for 12 hours or more to remove moisture. For Example 4, this glass was then crushed and granulated to obtain glass powder. Furthermore, for Examples 1 to 3 and 7, the dried flake-like glass obtained above was heated at a heating rate of 10 to 100°C / min, and then heat-treated at 950°C for 6 to 12 hours according to the conditions for each powder to crystallize. Then, it was cooled to room temperature at a cooling rate of 10 to 20°C / min to obtain glass ceramics, which were similarly pulverized and sizing to obtain glass ceramic powder. The pulverization and sizing conditions were determined based on the target BET specific surface area and average particle size (D 50 The composition and firing conditions were adjusted to achieve this result.

[0052] On the other hand, for Examples 5 and 6, LiCO3, Li3PO4, H3PO4, TiO2, and Al(PO3)3 were used as raw materials. The final product was weighed and uniformly mixed so that the composition was as shown in Table 1 below, expressed in mass percent on an oxide basis. The mixture was then formed into pellets approximately 15 mm in diameter and 5 mm thick, placed in a platinum crucible, covered with a lid of the same material, and heated in an electric furnace at a heating rate of 50°C / min, followed by calcination at 1000°C for 10 hours. After cooling to room temperature, the pellets were removed, dry-ground to approximately 100 μm or less, and then formed into pellets again in the same manner. The crucible and lid were then placed in an electric furnace and heated at a heating rate of 10°C / min, followed by final calcination (sintering) at 1200°C for 4 hours. The mixture was then cooled to room temperature at 20°C / min to obtain ceramics, which were then ground and granulated to obtain ceramic powder. Furthermore, for Comparative Examples 1 and 2, the component composition, BET specific surface area, and average particle diameter (D 50 The ceramic powder was prepared in the same manner as above, except that the ) was changed. In all cases, the grinding conditions and sizing conditions were set to the target BET specific surface area and average particle size (D 50 The composition and firing conditions were adjusted to achieve the above. In addition, as comparative example 3, Li manufactured by Toyoshima Seisakusho Co., Ltd. 6.75 La3Zr 1.75 Nb 0.25 O 12 (100 wt% concentration, LLZ ceramic powder) was also prepared.

[0053] Furthermore, the crystalline phase of the glass ceramic powders in Examples 1-3 and 7, and the ceramic powders in Examples 5-6, was confirmed by X-ray diffraction (XRD) measurement (using an automated X-ray diffractometer, Bruker's "D8 DISCOVER"), and it was confirmed that in all cases, more than 50% by mass of the total crystalline phase consisted of LATP crystals. In addition, no diffraction peaks were observed in Example 4, confirming that it was amorphous (non-crystalline).

[0054] <Evaluation of Lithium-Ion Conductive Inorganic Oxide Powders> For the obtained glass powder, glass-ceramic powder, and ceramic powder, the lithium-ion conductivity at 25°C, BET specific surface area, and average particle size (D) were evaluated. 50The component composition and HF trapping capacity of each powder were measured and evaluated. The measurements were performed as follows. The results are summarized in Table 1 below. Furthermore, Figure 1 shows a graph illustrating the relationship between BET / average particle size and HF trapping capacity for each powder, and Figure 2 shows a graph illustrating the relationship between BET × Al2O3 and HF trapping capacity for each powder.

[0055] [Lithium-ion conductivity (S / cm) at 25°C] Examples 1-4 and 7 used flake-shaped glass or flake-shaped glass that had been crystallized as samples for lithium-ion conductivity measurement, while Examples 5 and 6 used sintered bodies after firing as samples. Gold electrodes were formed on each sample as blocking electrodes using a magnetron sputtering apparatus (Sanyu Electronics, SC-701HMC), and impedance measurements were performed at 25°C under the conditions of frequency 0.1 Hz to 7 MHz, amplitude voltage 10 mV, and open-circuit voltage, and the lithium-ion conductivity (S / cm) was calculated.

[0056] [BET specific surface area (m 2 ( / g) For each of the above powders, use approximately 0.5g as a sample (measured value is 1m 2 Using the above adjustments, the material is crushed in an agate mortar as a pretreatment, degassed at 300°C for 30 min to remove surface impurities (using N2 (nitrogen) as the adsorbent gas, with a flow rate of 25 mL / min), and then the BET specific surface area (m²) is determined by the BET single-point method using a MOUNTECH Macorb HM-1201 fully automatic specific surface area meter. 2 The amount (per g) was measured, and the average of the two measurements was calculated.

[0057] [Average particle diameter (D 50 For each of the above powders, the average particle diameter (50% diameter (D) based on volume) was determined using a laser diffraction / scattering particle size distribution analyzer (Microtrac MT3300, manufactured by Microtrac Bell). ５０ The size (μm) was measured.

[0058] [Component Composition (mass %) in Oxide Equivalents)] Each of the above powders was analyzed using an ICP emission spectrometer (Agilent Technologies, ICP-OES 5900, measurement conditions: nebulizer flow rate 0.70 L / min, Li measurement wavelength 670.783 nm) to determine the Li content in each powder, and the content (mass) in terms of Li2O equivalent was calculated. In addition, each of the above powders was separately analyzed using an XRF analyzer (XRF: Rigaku Corporation, Primus II 4 kW tube specification, measurement conditions: FP method) to determine the content of each component other than Li. Assuming that all of these components are oxides, the total mass was extrapolated with the Li2O content calculated from the above ICP analysis, and the content of each oxide (mass %) in terms of oxide equivalents was calculated based on this total mass (100 mass %).

[0059] [HF Trap Capacity] 60 g of an electrolyte containing 1 ppm to 40 ppm of HF (hydrogen fluoride) and 20 ppm or less of water (electrolyte components: 1 mol / L LiPF6, solvent: ethylene carbonate: ethyl methyl carbonate = 3:7) was mixed with 2 g of any of the above powders (pre-dried under vacuum at 160°C for 24 hours using a glass tube oven (Büch Co., Ltd., B-585)) and sealed with aluminum laminate. After storing this in a 60°C constant temperature bath for one week, the electrolyte was extracted to prepare a sample for HF concentration measurement. This sample was diluted with pure water and neutralized using a 0.01 mol / L sodium hydroxide solution in an automatic titrator. Assuming that all the acids in the electrolyte were HF, the HF trap capacity was calculated from the HF concentration using the following formula.

[0060] HF concentration = (D - B) × K × F × M × 1000 / S D: Titration volume of sodium hydroxide solution to the endpoint (mL) B: Titration volume of blank sodium hydroxide solution (mL) K: Molecular weight of HF (20.0063) F: Sodium hydroxide solution factor M: Sodium hydroxide concentration (0.01 mol / L) S: Sample volume (g) HF trapping capacity = 100 × (1 / HF concentration)

[0061] <Tests using lithium-ion secondary batteries equipped with electrodes containing lithium-ion conductive inorganic oxide powder> Electrodes (positive electrodes) were formed using the glass powder, glass-ceramic powder, and ceramic powder obtained above, and the discharge capacity retention rate was confirmed and evaluated in tests using lithium-ion secondary batteries equipped with these electrodes. Specifically, the tests were conducted as follows.

[0062] [Electrode and Battery Fabrication] 1) Preparation of the positive electrode Using a rotation-orbit mixer (Sinky Co., Ltd., Awatori Rentaro), 98 wt% of LiCoO2 was mixed as the positive electrode active material, 1 wt% of acetylene black as a conductive additive, 1 wt% of PVdF as a binder, and 1 wt% of any of the above powders. NMP (N-methylpyrrolidone) was added to adjust the viscosity, and the mixture was degassed to obtain a paste-like slurry. This slurry was applied to 20 μm Al foil using an automatic coating machine (Hosen Co., Ltd., HSCM20-800S) and dried at 120°C. The basis capacity of the electrode (discharge capacity per unit area of ​​the active material layer applied to the substrate) was 3.6 mAh / cm². 2 This was then processed using a roll press machine (Housensha, HSR-60150H) to a density of 3.5 g / cm³. 3 1) Preparation of the negative electrode Using a rotation-orbit mixer (Thinky Co., Ltd.), 97.5 wt% artificial graphite was mixed as the negative electrode active material, 1 wt% CMC as a thickener, and 1.5 wt% SBR as a binder. Ion-exchanged water was added to prepare a paste-like slurry. This slurry was applied to a 16.5 μm Cu foil using an automatic coating machine (Hosen Co., Ltd., HSCM20-800S) and dried at 120 °C. The basis capacity of the electrode was 4.0 mAh / cm². 2 This was then processed using a roll press machine (Housensha, HSR-60150H) to a density of 1.4 g / cm³. 31) The material was adjusted to a film thickness of 90 μm and pressed, punched out to 30.5 mm x 40.5 mm using a press cutter (manufactured by Aichi Technical Co., Ltd.), and vacuum dried at 160°C for 16 hours using a glass tube oven (manufactured by Nippon Buch Co., Ltd., B-585). 3) Battery fabrication In a dry room (temperature 23°C, dew point temperature below -50°C), the positive and negative electrodes obtained in 1) and 2) above were tab-welded so that the A / C ratio (volume ratio of positive electrode active material to negative electrode active material) was 1.2, and together with a separator (polypropylene, film thickness 22 μm), they were placed in a laminate resin film and heat-pressed with a sealer, an electrolyte (electrolyte component: 1 mol / L LiPF6, solvent: ethylene carbonate: ethyl methyl carbonate = 3:7) was injected to impregnate the electrodes and separator, and the battery was fabricated by vacuum sealing (vacuum degassing and sealing).

[0063] [Confirmation of Discharge Capacity Retention Rate] For all the batteries produced, the following chemical conversion treatment, vacuum degassing and resealing (same as the vacuum sealing during the production of the cell batteries described above), and the following aging were performed in this order using a charge / discharge device (ACD-M01, manufactured by Asuka Electronics Co., Ltd.) and a small environmental test machine (SH-242, manufactured by ESPEC Corporation) for temperature control. Then, the following cycle tests were conducted to confirm the discharge capacity in each cycle, and the discharge capacity retention rate at 300 cycles relative to the discharge capacity at 1 cycle was determined. These results are summarized in Table 1 below. Figure 3 shows a graph illustrating the relationship between the HF trapping ability of each powder mixed in the positive electrode and the discharge capacity retention rate at 300 cycles of a battery equipped with that positive electrode, and Figure 4 shows a graph illustrating the relationship between the number of cycles and the discharge capacity retention rate for the battery using Example 2 and the battery using Comparative Example 3. Chemical treatment: CC-CV charge (0.05C, 4.4V-0.01C cutoff, 45℃), CC discharge (0.1C, 3.0V cutoff, 45℃), CC-CV charge (0.1C, 4.4V-0.05C cutoff, 45℃), CC discharge (0.1C, 3.0V cutoff, 45°C). Aging: CC-CV charge (0.2C, 4.4V-0.05C cutoff, 25°C), CC discharge (0.2C, 3.0V cutoff, 25°C). Cycle test: A test is conducted by repeating a cycle of CC-CV charging (1.0C, 4.4V - 0.05C cutoff, 25℃) and CC discharge (1.0C, 3.0V cutoff, 25℃), and checking the discharge capacity (mAh / g) at the first cycle and every 10 cycles up to the 300th cycle.

[0064]

[0065] These results show that by using glass powder, glass ceramic powder containing LATP crystals, or ceramic powder containing LATP crystals having a predetermined composition and a BET specific surface area within a predetermined range, the HF trapping capacity becomes above a predetermined level, and the discharge capacity maintenance rate of a predetermined lithium-ion secondary battery equipped with a positive electrode containing this was 73% or more after 300 cycles (Examples 1-7). In particular, in the glass ceramic powder or ceramic powder mentioned above, the product of the BET specific surface area and the content of the Al2O3 component (BET × Al2O3), or the average particle diameter (D 50 The higher the ratio of the BET specific surface area to the HF trapping capacity (BET / average particle diameter), the more likely it is that the HF trapping capacity will be higher, and the discharge capacity retention rate of lithium-ion secondary batteries equipped with a positive electrode containing this powder will tend to be higher. On the other hand, the powders of Comparative Examples 1 and 2, whose composition and BET specific surface area were outside the specified range, had an HF trapping capacity of less than 2.0, and the discharge capacity retention rate of lithium-ion secondary batteries equipped with a positive electrode containing this powder after 300 cycles was less than 67%. Similarly, the powder of Comparative Example 3 (LLZ ceramic powder), whose composition was completely different from that of the above examples, also had an HF trapping capacity of less than 2.0, and the discharge capacity retention rate of lithium-ion secondary batteries equipped with a positive electrode containing this powder was not high, and the effects seen in the above examples were not obtained.

[0066] This application claims priority based on Japanese Patent Application No. 2024-199386, filed on 15 November 2024, and incorporates all of its disclosures herein.

Claims

1. In terms of oxide mass percentage, it contains 4.0-6.0% Li2O, 3.0-9.0% Al2O3, 31.0-40.0% TiO2, and 49.0-57.0% P2O5, with a BET specific surface area of ​​8 m². 2 / g or more 35m 2 An inorganic oxide powder having a density of less than or equal to / g and an HF trapping capacity of 2.0 to 9.

0.

2. The inorganic oxide powder according to claim 1, wherein the product of the BET specific surface area and the Al2O3 content (BET × Al2O3) is 30 or more and 300 or less.

3. The average particle size (D) of the inorganic oxide powder. 50 The inorganic oxide powder according to claim 1 or 2, wherein the ratio of the BET specific surface area to the (BET / average particle diameter) is 10 or more.

4. The inorganic oxide powder according to claim 1 or 2, wherein the content of the Al2O3 component is 5.0% or more, and the content of the TiO2 component is 33.0% or more.

5. The inorganic oxide powder according to claim 1 or 2, wherein the content of the Al2O3 component is 5.0% or more, and the sum of the content of the Li2O component, the Al2O3 component, and the TiO2 component (Li2O + Al2O3 + TiO2) is 45.5% or more.

6. The inorganic oxide powder according to claim 1 or 2, wherein the inorganic oxide powder is glass powder.

7. The inorganic oxide powder according to claim 1 or 2, which is a glass ceramic powder or ceramic powder containing LATP crystals.

8. A lithium-ion secondary battery comprising an electrode containing the inorganic oxide powder described in claim 1 or 2, and an electrolyte layer containing a lithium salt containing fluorine as an electrolyte component.

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