JP2018150217A - Composite oxide, positive electrode active material, nonaqueous electrolyte electricity storage device and method for producing composite oxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a composite oxide capable of improving the discharge capacity maintenance rate of a nonaqueous electrolyte electricity storage device when used for a positive electrode active material of the nonaqueous electrolyte electricity storage device; a positive electrode active material containing such a composite oxide; a positive electrode having the positive electrode active material; a nonaqueous electrolyte electricity storage device having the positive electrode; and a method for producing the composite oxide.SOLUTION: There is provided a composite oxide which includes lithium, molybdenum and an element (A), wherein the element (A) is boron, carbon, nitrogen, fluorine, silicon, phosphorus, sulfur, chlorine, zinc, gallium, germanium, arsenic, selenium, bromine, tin, antimony, tellurium, bromine or a combination thereof and the content of the element (A) to the total content of the molybdenum and the element (A) is 1 mol% or more and less than 50 mol%.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a composite oxide, a positive electrode active material, a positive electrode, a nonaqueous electrolyte storage element, and a method for producing the composite oxide.

  Nonaqueous electrolyte secondary batteries typified by lithium ion secondary batteries are widely used in electronic devices such as personal computers and communication terminals, automobiles and the like because of their high energy density. The nonaqueous electrolyte secondary battery generally has a pair of electrodes electrically isolated by a separator and a nonaqueous electrolyte interposed between the electrodes, and transfers ions between the electrodes. It is comprised so that it may charge / discharge. In addition, capacitors such as lithium ion capacitors and electric double layer capacitors are widely used as nonaqueous electrolyte storage elements other than nonaqueous electrolyte secondary batteries.

Various composite oxides and the like are used for the active material contained in the positive electrode of the nonaqueous electrolyte storage element. As such a composite oxide, LiMoO ₂ (see Non-Patent Document 1) or Li _1.211 Mo _0.467 Cr _0.3 O ₂ (see Non-Patent Document 1) having a crystal structure belonging to the space group R-3m or C2 / m. A composite oxide containing lithium and molybdenum such as Non-Patent Document 2) has been developed.

K. Ben-Kamel, N.A. Amdouni, H.M. Grout, A.M. Mauger, K.M. Zaghib, C.I. M.M. Julien, “Journal of Power Sources”, 2012, Vol. 202, p314-321. Jinhyuk Lee, Alexander Urban, Xin Li, Dong Su, Geoffroy Hautier, Gerbrand Ceder, “Science”, 2014, Vol. 343, p519-522

  However, there is room for improvement in the non-aqueous electrolyte electricity storage device using each of the above complex oxides as the positive electrode active material, for example, because the capacity retention rate is not sufficient. In addition, since the composite oxide containing chromium can be oxidized to highly toxic hexavalent chromium, industrial use is limited in terms of safety and environmental impact.

  This invention is made | formed based on the above situations, The objective raises the discharge capacity maintenance factor of this nonaqueous electrolyte electrical storage element, when it uses for the positive electrode active material of a nonaqueous electrolyte electrical storage element. Provided is a composite oxide that can be used, a positive electrode active material containing such a composite oxide, a positive electrode having this positive electrode active material, a nonaqueous electrolyte storage element having this positive electrode, and a method for producing the above composite oxide It is.

  In order to solve the above problems, a composite oxide according to one embodiment of the present invention includes lithium, molybdenum, and an element (A), and the element (A) is boron, carbon, nitrogen, fluorine, silicon, phosphorus , Sulfur, chlorine, zinc, gallium, germanium, arsenic, selenium, bromine, tin, antimony, tellurium, iodine or a combination thereof, and the element (A) relative to the total content of the molybdenum and the element (A) Is a composite oxide having a content of 1 mol% or more and less than 50 mol%.

  The positive electrode active material according to another embodiment of the present invention is a positive electrode active material for a non-aqueous electrolyte electricity storage element containing the composite oxide.

  The positive electrode according to another embodiment of the present invention is a positive electrode for a non-aqueous electrolyte electricity storage element having the positive electrode active material.

  The nonaqueous electrolyte storage element according to another embodiment of the present invention is a nonaqueous electrolyte storage element having the positive electrode.

  A method for producing a composite oxide according to another embodiment of the present invention includes treating one or more kinds of oxides by a mechanochemical method, wherein the one or more kinds of oxides are lithium, molybdenum, and an element. (A), and the element (A) is boron, carbon, nitrogen, fluorine, silicon, phosphorus, sulfur, chlorine, zinc, gallium, germanium, arsenic, selenium, bromine, tin, antimony, tellurium, iodine or these It is the manufacturing method of the complex oxide which is a combination of these.

  According to the present invention, when used as a positive electrode active material of a nonaqueous electrolyte storage element, the composite oxide capable of increasing the discharge capacity retention rate of the nonaqueous electrolyte storage element, containing such a composite oxide A positive electrode active material, a positive electrode having the positive electrode active material, a non-aqueous electrolyte storage element having the positive electrode, and a method for producing the composite oxide can be provided.

FIG. 1 is an external perspective view showing a nonaqueous electrolyte storage element according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing a power storage device configured by assembling a plurality of nonaqueous electrolyte power storage elements according to an embodiment of the present invention. FIG. 3 is an X-ray diffraction pattern of the composite oxides of Examples 1 to 4 and Comparative Examples 2 and 3. FIG. 4 is an X-ray diffraction pattern of the composite oxides of Examples 5 and 6 and Comparative Example 4. FIG. 5 is a graph showing calculated values, measured values, and differences between them in Rietveld analysis for the complex oxide of Example 1. 6 is a graph showing calculated values (two-phase coexistence model), measured values, and differences between them in Rietveld analysis for the composite oxide of Example 2. FIG. FIG. 7 is a graph showing calculated values (one-phase model), measured values, and differences thereof in Rietveld analysis for the composite oxide of Example 2. FIG. 8 is a graph showing calculated values, measured values, and differences between them in Rietveld analysis for the composite oxide of Example 5. FIG. 9 is a discharge curve of the nonaqueous electrolyte electricity storage device of Example 1.

  The composite oxide according to an embodiment of the present invention includes lithium, molybdenum, and the element (A), and the element (A) is boron, carbon, nitrogen, fluorine, silicon, phosphorus, sulfur, chlorine, zinc, gallium. , Germanium, arsenic, selenium, bromine, tin, antimony, tellurium, iodine or a combination thereof, and the content of the element (A) with respect to the total content of the molybdenum and the element (A) is 1 mol% or more. It is a complex oxide that is less than 50 mol%.

When the composite oxide is used as a positive electrode active material of a nonaqueous electrolyte storage element, the discharge capacity retention rate of the nonaqueous electrolyte storage element can be increased. Although this reason is not certain, the following reason is guessed. In general, when an oxide containing molybdenum is used as the positive electrode active material, the oxide is likely to be deteriorated due to stress caused by expansion and contraction accompanying the oxidation-reduction reaction of molybdenum. On the other hand, the element (A) is an element having a strong covalent bond with oxygen and has a normal potential range (eg, 1.2 V (vs. Li ^/ Li ⁺ ) or more when used as a positive electrode active material 4 .4 V (vs. Li / Li ⁺ ) or lower) is an element that hardly causes a redox reaction. All of the above elements (A) are elements having an electronegativity of Allred-Rocho of 1.7 or more, and thus have high covalent bonding with oxygen. In the complex oxide containing such an element (A), an AOx unit is incorporated in the structure, and the structure hardly changes during the oxidation-reduction reaction of molybdenum during charge / discharge. For this reason, since the said stress is relieve | moderated and progress of deterioration is suppressed, it is estimated that a discharge capacity maintenance factor increases. Furthermore, since the composite oxide contains an element (A) having a high covalent bond with oxygen, it has excellent thermal stability and safety when used as a positive electrode active material of a nonaqueous electrolyte storage element. Etc. Furthermore, in the composite oxide, the content of the element (A) with respect to the total content of molybdenum and the element (A) is 1 mol% or more and less than 50 mol%. When used as an active material, this non-aqueous electrolyte electricity storage element can have a sufficient discharge capacity.

The composite oxide is preferably represented by the following formula (1).
Li _{1 + x} Mo _1-y A _y O _z (1)
(In the formula (1), A is B, C, N, F, Si, P, S, Cl, Zn, Ga, Ge, As, Se, Br, Sn, Sb, Te, I, or a combination thereof. (0 ≦ x, 0.01 ≦ y <0.5, 0 <z)

  When the composite oxide has a composition represented by the above formula (1), the discharge capacity retention rate of the nonaqueous electrolyte storage element when used as the positive electrode active material can be further increased.

  It is preferable that the complex oxide includes a crystal structure that can be assigned to the space group Fm-3m. When the composite oxide includes the above crystal structure, the discharge capacity retention rate of the nonaqueous electrolyte storage element when used as the positive electrode active material can be further increased. The reason for this is not clear, but it is presumed that the crystal structure is a structure that can alleviate the stress during the oxidation-reduction reaction of molybdenum described above.

  The positive electrode active material which concerns on one Embodiment of this invention is a positive electrode active material for nonaqueous electrolyte electrical storage elements containing the said complex oxide. Since the positive electrode active material contains the composite oxide, it is possible to increase the discharge capacity maintenance rate of the nonaqueous electrolyte storage element. Moreover, the nonaqueous electrolyte electricity storage element using the said positive electrode active material can have sufficient discharge capacity.

  The positive electrode which concerns on one Embodiment of this invention is a positive electrode for nonaqueous electrolyte electrical storage elements which has the said positive electrode active material. Since the positive electrode includes the positive electrode active material, the discharge capacity maintenance rate of the nonaqueous electrolyte storage element can be increased.

  The nonaqueous electrolyte storage element according to one embodiment of the present invention is a nonaqueous electrolyte storage element having the positive electrode. The nonaqueous electrolyte electricity storage element has a high discharge capacity maintenance rate.

  A method for producing a composite oxide according to an embodiment of the present invention includes treating one or more kinds of oxides by a mechanochemical method, wherein the one or more kinds of oxides include lithium, molybdenum, and an element ( A), and the element (A) is boron, carbon, nitrogen, fluorine, silicon, phosphorus, sulfur, chlorine, zinc, gallium, germanium, arsenic, selenium, bromine, tin, antimony, tellurium, iodine or these This is a method for producing a composite oxide which is a combination. According to the manufacturing method, when used as a positive electrode active material of a nonaqueous electrolyte storage element, a composite oxide capable of increasing the discharge capacity retention rate of the nonaqueous electrolyte storage element can be manufactured. In addition, according to the manufacturing method, a composite oxide that is easy to synthesize and has few impurities can be obtained.

  Hereinafter, a composite oxide, a method for producing the same, a positive electrode active material, a positive electrode, and a nonaqueous electrolyte storage element according to an embodiment of the present invention will be described in detail.

<Composite oxide>
The composite oxide according to an embodiment of the present invention includes lithium (Li), molybdenum (Mo), and element (A).

  The element (A) is boron (B), carbon (C), nitrogen (N), fluorine (F), silicon (Si), phosphorus (P), sulfur (S), chlorine (Cl), zinc (Zn ), Gallium (Ga), germanium (Ge), arsenic (As), selenium (Se), bromine (Br), tin (Sn), antimony (Sb), tellurium (Te), iodine (I) or combinations thereof It is. The element (A) may be only one kind or two or more kinds. Among the above elements (A), boron, carbon, nitrogen, fluorine, phosphorus, sulfur, chlorine, germanium, arsenic, selenium, bromine, tellurium and iodine having an electronegativity of all red locomotive of 2.0 or more are preferable. Further, boron, carbon, nitrogen, silicon, phosphorus, sulfur and germanium are also preferable, and carbon, phosphorus and germanium are more preferable. By using these elements, the discharge capacity maintenance rate of the nonaqueous electrolyte storage element can be further increased. The element (A) is preferably boron, carbon, nitrogen, silicon, phosphorus, sulfur or a combination thereof. By using these relatively easily available elements, the manufacturing cost of the composite oxide can be suppressed. Further, as the element (A), boron, carbon, nitrogen, fluorine, silicon, phosphorus, sulfur, chlorine, zinc, gallium, germanium, bromine, tin, tellurium and iodine are also preferable. By using these elements having low toxicity, safety can be improved.

  In the composite oxide, the lower limit of the content of the element (A) with respect to the total content of the molybdenum and the element (A) is 1 mol%, preferably 5 mol%, more preferably 10 mol%. 15 mol% may be more preferable. By setting the content of the element (A) to be equal to or higher than the above lower limit, the discharge capacity retention rate can be increased.

  The content of the element (A) relative to the total content of the molybdenum and the element (A) is less than 50 mol%, and the upper limit of the content is preferably 45 mol%, more preferably 35 mol%. It may be preferred, 25 mol% may be more preferred, and 15 mol% may be even more preferred. By making content of an element (A) below the said upper limit, discharge capacity can be enlarged or a discharge capacity maintenance factor can be raised more.

  The lithium content in the composite oxide is not particularly limited. Lithium composition ratio greatly fluctuates due to charging / discharging, lithium composition ratio may be larger than at synthesis at the end of discharge, and lithium raw material is added in excess of the theoretical composition ratio during synthesis Therefore, the lithium content in the composite oxide does not significantly affect the performance as the positive electrode active material. The lower limit of the lithium content in the composite oxide may be 100 mol% or 110 mol% with respect to the total content of molybdenum and the element (A). On the other hand, the upper limit of the lithium content may be 300 mol% or 200 mol% with respect to the total content of molybdenum and the element (A).

  The oxygen content in the composite oxide is not particularly limited, and is usually determined from the composition ratio of other elements, the valence of other elements, and the like. However, since it may be an oxygen-deficient or oxygen-rich oxide, it is not determined only by the composition and valence of other elements. The lower limit of the oxygen content in the composite oxide may be 200 mol% or 220 mol% with respect to the total content of molybdenum and the element (A). On the other hand, the upper limit of the oxygen content may be 400 mol% or 300 mol% with respect to the total content of molybdenum and the element (A).

  The complex oxide may contain elements other than lithium, molybdenum, element (A), and oxygen in a range that does not affect the operational effects of the present invention. Examples of such other optional elements include metal elements such as sodium, potassium, magnesium, calcium, and indium. The upper limit of the content of these optional elements is preferably 50 mol%, more preferably 20 mol%, still more preferably 10 mol%, and more preferably 1 mol% with respect to the total content of molybdenum and the element (A). Is more preferable, and 0.1 mol% is particularly preferable. This optional element may not be substantially contained.

  Since the complex oxide does not contain chromium as an essential component, there are few industrial usage restrictions. That is, the composite oxide can have a composition that does not substantially contain chromium. When the complex oxide does not substantially contain chromium, the safety is higher than that containing chromium. Here, “substantially not containing chromium” means that chromium is not intentionally added. The chromium content in the composite oxide is preferably 1,000 ppm (0.1% by mass) or less. Moreover, it is also preferable that the chromium content is 0.1 mol% or less with respect to the total content of molybdenum and the element (A). The content of each element in the complex oxide is a value measured by an ICP emission spectroscopic analyzer.

The complex oxide can be suitably represented by the following formula (1).
Li _{1 + x} Mo _1-y A _y O _z (1)
In formula (1), A is B, C, N, F, Si, P, S, Cl, Zn, Ga, Ge, As, Se, Br, Sn, Sb, Te, I, or a combination thereof. . 0 ≦ x, 0.01 ≦ y <0.5, and 0 <z.

  The lower limit of x in the above formula (1) may be 0.1. The upper limit of x may be 2 or 1.

  Y in the above formula (1) indicates the molar ratio of the content of the element (A) to the total content of molybdenum and the element (A). The lower limit of y is preferably 0.05, more preferably 0.1, and even more preferably 0.15. Further, the upper limit of y is preferably 0.45, more preferably 0.35, more preferably 0.25, and even more preferably 0.15.

  The lower limit of z in the above formula (1) may be 2 or 2.2. Also, the upper limit of z may be 4 or 3.

The complex oxide may be substantially represented by the following formula (1-1) or formula (1-2).
Li _{1 + 2y} Mo _1-y A _y O _{2 + 2y} (1-1)
Li _{1 + y} Mo _1-y A _y O _{2 + y} (1-2)
In formula (1-1) and formula (1-2), y has the same meaning as y in formula (1).

The above formula (1-1) is theoretically obtained by using LiMoO ₂ and Li ₃ AO ₄ (Li ₃ PO ₄ or the like) as raw materials in a molar ratio of 1-y: y. Here, comparing the formula (1) with the formula (1-1) and considering that lithium and oxygen are not clearly determined as described above, 0.9 ≦ (1 + x) / (1 + 2y) ≦ 1.1 and 0.9 ≦ z / (2 + 2y) ≦ 1.1 may be satisfied.

The above formula (1-2) is theoretically obtained by using LiMoO ₂ and Li ₂ AO ₃ (Li ₂ CO ₃ , Li ₂ GeO _3, etc.) as raw materials in a molar ratio of 1-y: y. Here, comparing the formula (1) with the formula (1-2) and considering that lithium and oxygen are not clearly determined as described above, 0.9 ≦ (1 + x) / (1 + y) ≦ 1.1 and 0.9 ≦ z / (2 + y) ≦ 1.1 may be satisfied.

  The composite oxide preferably includes a crystal structure that can be assigned to the space group Fm-3m. The crystal structure that can be assigned to the space group Fm-3m means that it has a peak that can be assigned to the space group Fm-3m in the X-ray diffraction pattern. The complex oxide may have a crystal structure belonging to the space group Fm-3m. However, the crystal structure may not be maintained by repeated charge and discharge. Therefore, it is preferable that the crystal structure before charging / discharging belongs to the space group. Note that “−3” in the space group “Fm−3m” represents the target element of the three-fold anti-axis, and should be described by adding a bar “−” above “3”. The composite oxide may have a crystal structure other than the space group Fm-3m, such as the space group R-3m. The complex oxide may be a crystal body having a plurality of crystal structures. The lower limit of the content ratio of the crystal structure that can be assigned to the space group Fm-3m in the composite oxide is preferably 5% by mass, more preferably 10% by mass, and still more preferably 20% by mass. The upper limit of this content ratio may be 100% by mass.

  X-ray diffraction measurement of the composite oxide is performed by powder X-ray diffraction measurement using an X-ray diffractometer (“MiniFlex II” manufactured by Rigaku), with the source being CuKα ray, the tube voltage being 30 kV and the tube current being 15 mA. . At this time, the diffracted X-rays are detected by a high-speed one-dimensional detector (D / teX Ultra 2) through a Kβ filter having a thickness of 30 μm. The sampling width is 0.01 °, the scanning speed is 5 ° / min, the divergence slit width is 0.625 °, the light receiving slit width is 13 mm (OPEN), and the scattering slit width is 8 mm. Based on the obtained X-ray diffraction data, the crystal structure can be analyzed by Rietveld analysis using the “Rietan 2000” program (F. Izumi and T. Ikeda, Mater. Sci. Forum, 198 (2000)). it can. For the space group, the same result can be obtained by using comprehensive powder X-ray analysis software “PDXL” (manufactured by Rigaku).

<Production method of composite oxide>
Although the manufacturing method of the said complex oxide is not specifically limited, The following manufacturing methods are preferable. That is, the method for producing a composite oxide according to an embodiment of the present invention comprises treating one or more kinds of oxides by a mechanochemical method, wherein the one or more kinds of oxides are lithium, molybdenum, and Element (A), wherein the element (A) is boron, carbon, nitrogen, fluorine, silicon, phosphorus, sulfur, chlorine, zinc, gallium, germanium, arsenic, selenium, bromine, tin, antimony, tellurium, iodine or This is a method for producing a composite oxide which is a combination of these.

  According to the manufacturing method, a composite oxide containing lithium, molybdenum, and the element (A) can be obtained by treating one or more kinds of oxides containing a predetermined element by a mechanochemical method. Moreover, in the said manufacturing method, the complex oxide of a desired composition ratio can be obtained by adjusting the mixing ratio of multiple types of oxides. In the method for producing a composite oxide according to an embodiment of the present invention, the content of element (A) with respect to the total content of molybdenum and element (A) in the obtained composite oxide is particularly limited. is not.

  The mechanochemical method (also referred to as mechanochemical treatment) refers to a synthesis method utilizing a mechanochemical reaction. The mechanochemical reaction refers to a chemical reaction such as a crystallization reaction, a solid solution reaction, or a phase transition reaction that uses high energy locally generated by mechanical energy such as friction and compression in the crushing process of a solid substance. Examples of the apparatus for performing the mechanochemical method include ball mills, bead mills, vibration mills, turbo mills, mechano fusions, and disk mills. Among these, a ball mill is preferable.

  As an oxide used as a raw material, three or more kinds of oxides including lithium, oxide containing molybdenum, and oxide containing element (A) can be used. And an oxide containing lithium and the element (A) are preferably used. An oxide containing molybdenum and the element (A) can also be used. Note that in the case where a plurality of types of oxides are used, it is only necessary that the plurality of types of oxides contain lithium, molybdenum, and the element (A).

Examples of the oxide containing lithium and molybdenum include LiMoO ₂ , Li ₂ MoO ₃ , and Li ₄ MoO ₅ . Of these, LiMoO ₂ is preferable.

Examples of the oxide containing lithium and the element (A) include LiBO ₂ , Li ₃ BO ₃ , Li ₂ CO ₃ , LiNO ₃ , Li ₄ SiO ₄ , Li ₃ PO ₄ , Li ₂ SO ₄ , and Li ₂ Ge ₄ O _9. Li ₂ GeO ₃ , Li ₆ Ge ₂ O ₇ , Li ₄ GeO ₄ , Li ₂ ZnO ₂ , Li ₆ ZnO ₄ , Li ₄ ZnO ₃ , LiGaO ₂ , Li ₅ GaO ₄ , Li ₂ SnO ₃ , Li ₈ SnO _{6 , Li 2 TeO 3, Li 4} TeO 5, Li 6 TeO 6, LiClO 2, LiClO 3, LiBrO 2, LiBrO 3, LiIO 3, LiAsO 3, Li 3 AsO 4, LiSbO 3, Li 3 SbO 4, Li 5 SbO ₅ , Li ₇ SbO ₆ , Li ₂ SeO ₄ , Li ₄ SeO _{5 and the} like.

Examples of the oxide containing molybdenum and the element (A) include MoOF ₄ and MoO _2.4 F _0.6 .

  Note that in this manufacturing method, a kind of oxide containing lithium, molybdenum, and the element (A) may be processed by a mechanochemical method. Such an oxide containing lithium, molybdenum, and element (A) can be obtained, for example, by treating the above-described plurality of types of oxides by a known method such as a firing method.

  These oxides used as raw materials are usually in the form of powder, and the powdered oxide is subjected to treatment by a mechanochemical method. This treatment can be performed under an inert gas atmosphere such as argon or an active gas atmosphere, but is preferably performed under an inert gas atmosphere. The composite oxide obtained through such treatment is usually in the form of a powder.

<Positive electrode active material>
The positive electrode active material which concerns on one Embodiment of this invention is a positive electrode active material for nonaqueous electrolyte electrical storage elements containing the complex oxide which concerns on one Embodiment of this invention mentioned above. Specific aspects and preferred aspects of the composite oxide are as described above as an embodiment of the composite oxide of the present invention.

  According to the positive electrode active material according to an embodiment of the present invention, since the composite oxide is included, the discharge capacity maintenance rate of the nonaqueous electrolyte storage element can be increased. In addition, since the positive electrode active material does not contain chromium as an essential component, there are few industrial usage restrictions. Furthermore, according to the positive electrode active material containing the composite oxide, the discharge capacity of the nonaqueous electrolyte storage element can be increased.

The positive electrode active material may be formed only from the composite oxide, but may include other positive electrode active materials. As another positive electrode active material, for example, a composite oxide (Li _x CoO having a layered α-NaFeO ₂ type crystal structure) represented by Li _x MO _y (M represents at least one transition metal other than Mo) is used. _{2, Li x NiO 2, Li} x MnO 3, Li x Ni α Co (1-α) O 2, Li x Ni α Mn β Co (1-α-β) O 2 , etc., Li having a spinel type crystal structure _x Mn ₂ O ₄ , Li _x Ni _α Mn _(2-α) O _4, etc.), Li _w M ′ _x (XO _y ) _z (M ′ represents at least one transition metal other than Mo, and X is, for example, P, Si, B, polyanionic compound represented by the representative of the V or the _{like) (LiFePO 4, LiMnPO 4,} LiNiPO 4, LiCoPO 4, Li 3 V 2 (PO 4) 3, Li 2 MnSiO 4, Li 2 CoPO F, etc.) and the like. Moreover, in the said positive electrode active material, the complex oxide etc. which contain lithium and element (A), for example may contain.

  The lower limit of the content of the composite oxide in the positive electrode active material is preferably 50% by mass, more preferably 70% by mass, and still more preferably 90% by mass. Increasing the content of the composite oxide can sufficiently increase the discharge capacity retention rate of the nonaqueous electrolyte storage element.

<Positive electrode>
The positive electrode which concerns on one Embodiment of this invention is a positive electrode for nonaqueous electrolyte electrical storage elements which has the said positive electrode active material.

  The positive electrode which concerns on one Embodiment of this invention has a positive electrode base material and the positive electrode compound material layer distribute | arranged to this positive electrode base material directly or through an intermediate | middle layer.

  The positive electrode base material has conductivity. As the material of the substrate, metals such as aluminum, copper, titanium, tantalum, stainless steel, or alloys thereof are used. Among these, aluminum and aluminum alloys are preferable from the balance of potential resistance, high conductivity and cost. Moreover, foil, a vapor deposition film, etc. are mentioned as a formation form of a positive electrode base material, and foil is preferable from the surface of cost. That is, an aluminum foil is preferable as the positive electrode base material.

The said intermediate | middle layer is a coating layer of the surface of a positive electrode base material, and reduces the contact resistance of a positive electrode base material and a positive electrode compound material layer by including electroconductive particles, such as a carbon particle. The configuration of the intermediate layer is not particularly limited, and can be formed of a composition containing a resin binder and conductive particles, for example. “Conductive” means that the volume resistivity measured in accordance with JIS-H-0505 (1975) is 10 ⁷ Ω · cm or less, and “nonconductive” Means that the volume resistivity is more than 10 ⁷ Ω · cm.

  The positive electrode mixture layer is a layer formed from a so-called positive electrode mixture containing the positive electrode active material. The positive electrode mixture can contain optional components such as a conductive agent, a binder, a thickener, and a filler as necessary. The positive electrode mixture layer is formed by coating a slurry of the positive electrode mixture.

  The lower limit of the content of the positive electrode active material in the positive electrode mixture layer (positive electrode mixture) is, for example, 50% by mass, and preferably 60% by mass. On the other hand, the upper limit of the content may be, for example, 95% by mass or 90% by mass.

  The conductive agent is not particularly limited as long as it is a conductive material that does not adversely affect the performance of the storage element. Examples of such a conductive agent include natural or artificial graphite, furnace black, acetylene black, carbon black such as ketjen black, metal, conductive ceramics, and the like, and acetylene black is preferable. Examples of the shape of the conductive agent include powder and fiber.

  As the binder (binder), thermoplastic resins such as fluororesin (polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), etc.), polyethylene, polypropylene, polyimide; ethylene-propylene-diene rubber (EPDM), Examples thereof include elastomers such as sulfonated EPDM, styrene butadiene rubber (SBR) and fluororubber; polysaccharide polymers and the like.

  Examples of the thickener include polysaccharide polymers such as carboxymethylcellulose (CMC) and methylcellulose. When the thickener has a functional group that reacts with lithium, it is preferable to deactivate this functional group in advance by methylation or the like.

  The filler is not particularly limited as long as it does not adversely affect the performance of the storage element. Examples of the main component of the filler include polyolefins such as polypropylene and polyethylene, silica, alumina, zeolite, and glass.

<Nonaqueous electrolyte storage element>
A nonaqueous electrolyte storage element according to an embodiment of the present invention includes a positive electrode, a negative electrode, and a nonaqueous electrolyte. Hereinafter, a nonaqueous electrolyte secondary battery will be described as an example of a nonaqueous electrolyte storage element. The positive electrode and the negative electrode usually form an electrode body that is alternately superposed by stacking or winding via a separator. This electrode body is housed in a case, and the case is filled with a nonaqueous electrolyte. The non-aqueous electrolyte is interposed between the positive electrode and the negative electrode. Moreover, as said case, the well-known aluminum case, resin case, etc. which are normally used as a case of a nonaqueous electrolyte secondary battery can be used.

(Positive electrode)
As the positive electrode, the positive electrode according to one embodiment of the present invention is used. The details of the positive electrode are as described above.

(Negative electrode)
The negative electrode includes a negative electrode base material and a negative electrode mixture layer disposed on the negative electrode base material directly or via an intermediate layer. The intermediate layer can have the same configuration as the positive electrode intermediate layer.

  The negative electrode base material can have the same configuration as the positive electrode base material, but as a material, a metal such as copper, nickel, stainless steel, nickel-plated steel, or an alloy thereof is used. preferable. That is, copper foil is preferable as the negative electrode substrate. Examples of the copper foil include rolled copper foil and electrolytic copper foil.

  The negative electrode mixture layer is formed from a so-called negative electrode mixture containing a negative electrode active material. Moreover, the negative electrode composite material which forms a negative electrode composite material layer contains arbitrary components, such as a electrically conductive agent, a binder, a thickener, and a filler, as needed. Arbitrary components such as a conductive agent, a binder, a thickener, and a filler can be the same as those for the positive electrode mixture layer.

  As the negative electrode active material, a material that can occlude and release lithium ions is usually used. Specific negative electrode active materials include, for example, metals or semimetals such as Si and Sn; metal oxides or semimetal oxides such as Si oxide and Sn oxide; polyphosphate compounds; graphite (graphite) and amorphous Examples thereof include carbon materials such as carbon (easily graphitizable carbon or non-graphitizable carbon).

  Further, the negative electrode mixture (negative electrode mixture layer) includes typical nonmetallic elements such as B, N, P, F, Cl, Br, and I, Li, Na, Mg, Al, K, Ca, Zn, Ga, and Ge. Typical metal elements such as Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, Zr, Ta, Hf, Nb, and W may be contained.

(Separator)
As the material of the separator, for example, a woven fabric, a nonwoven fabric, a porous resin film, or the like is used. Among these, a porous resin film is preferable from the viewpoint of strength, and a nonwoven fabric is preferable from the viewpoint of liquid retention of the nonaqueous electrolyte. The main component of the separator is preferably a polyolefin such as polyethylene or polypropylene from the viewpoint of strength, and is preferably polyimide or aramid from the viewpoint of resistance to oxidative degradation. These resins may be combined.

  An inorganic layer may be provided between the separator and the electrode (usually a positive electrode). This inorganic layer is a porous layer also called a heat-resistant layer. Moreover, the separator by which the inorganic layer was formed in one surface of the porous resin film can also be used. The inorganic layer is usually composed of inorganic particles and a binder, and may contain other components.

(Nonaqueous electrolyte)
As said nonaqueous electrolyte, the well-known electrolyte normally used for a nonaqueous electrolyte electrical storage element (secondary battery) can be used. The non-aqueous electrolyte includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent.

  Examples of the non-aqueous solvent include cyclic carbonates such as ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and the like. A chain carbonate etc. can be mentioned.

Examples of the electrolyte salt include lithium salt, sodium salt, potassium salt, magnesium salt, onium salt, and the like, but lithium salt is preferable. Examples of the lithium salt include inorganic lithium salts such as LiPF ₆ , LiPO ₂ F ₂ , LiBF ₄ , LiClO ₄ , LiN (SO ₂ F) ₂ , LiSO ₃ CF ₃ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO Fluorohydrocarbon groups such as ₂ C ₂ F ₅ ) ₂ , LiN (SO ₂ CF ₃ ) (SO ₂ C ₄ F ₉ ), LiC (SO ₂ CF ₃ ) ₃ , LiC (SO ₂ C ₂ F ₅ ) ₃ A lithium salt having

  As the non-aqueous electrolyte, a room temperature molten salt, an ionic liquid, a polymer solid electrolyte, or the like can be used.

  The said nonaqueous electrolyte electrical storage element can be manufactured by using the positive electrode which concerns on one Embodiment of this invention. The manufacturing method includes, for example, a step of producing a positive electrode, a step of producing a negative electrode, a step of preparing a nonaqueous electrolyte, and an electrode body in which the positive electrode and the negative electrode are alternately superposed by being stacked or wound via a separator. Forming a positive electrode and a negative electrode (electrode body) in a case, and injecting the nonaqueous electrolyte into the case. After the injection, the nonaqueous electrolyte storage element can be obtained by sealing the injection port.

<Other embodiments>
The present invention is not limited to the above-described embodiment, and can be implemented in a mode in which various changes and improvements are made in addition to the above-described mode. For example, in the positive electrode, the intermediate layer may not be provided, and the positive electrode mixture may not form a clear layer. For example, the positive electrode may have a structure in which a positive electrode mixture is supported on a mesh-like positive electrode base material. Further, in the above embodiment, the description has been made centering on the form in which the nonaqueous electrolyte storage element is a secondary battery, but other nonaqueous electrolyte storage elements may be used. Examples of other nonaqueous electrolyte storage elements include capacitors (electric double layer capacitors, lithium ion capacitors) and the like.

  FIG. 1 shows a schematic diagram of a rectangular nonaqueous electrolyte storage element (secondary battery) 1 which is an embodiment of the nonaqueous electrolyte storage element. In the figure, the inside of the container is seen through. In the nonaqueous electrolyte storage element 1 shown in FIG. 1, an electrode body 2 is housed in a container (case) 3. The electrode body 2 is formed by winding a positive electrode including a positive electrode active material and a negative electrode including a negative electrode active material via a separator. The positive electrode is electrically connected to the positive electrode terminal 4 via the positive electrode lead 4 ′, and the negative electrode is electrically connected to the negative electrode terminal 5 via the negative electrode lead 5 ′.

  The configuration of the nonaqueous electrolyte storage element (secondary battery) is not particularly limited, and examples thereof include a cylindrical battery, a square battery (rectangular battery), a flat battery, and the like. The present invention can also be realized as a power storage device including a plurality of the above nonaqueous electrolyte power storage elements. One embodiment of a power storage device is shown in FIG. In FIG. 2, the power storage device 30 includes a plurality of power storage units 20. Each power storage unit 20 includes a plurality of nonaqueous electrolyte power storage elements 1. The power storage device 30 can be mounted as a power source for vehicles such as an electric vehicle (EV), a hybrid vehicle (HEV), a plug-in hybrid vehicle (PHEV), and the like.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

[Synthesis Example 1 (Comparative Example 1)] (Synthesis of lithium molybdenum composite oxide)
Lithium carbonate (Li ₂ CO ₃ ) (manufactured by Nacalai Tesque), molybdenum trioxide (MoO ₃ ) (manufactured by High-Purity Chemical Co., Ltd.), and acetylene black as a reducing agent were mixed at a molar ratio of Li: Mo: C of 4: Weighed out to be 4: 3. These were put into a zirconia pot having an internal volume of 80 mL containing 90 g (about 250 pieces) of zirconia balls having a diameter of 5 mm, and the lid was capped. This was set on a planetary ball mill ("Pulverisete 5" manufactured by FRITSCH), mixed for 9 minutes at a revolution speed of 120 rpm, and then put into a rest for 1 minute for a total of 6 times. Then, the lid was opened, the mixture in the pot was stirred with a spoon, and again the operation of mixing for 9 minutes at a revolution speed of 120 rpm and then resting for 1 minute was repeated a total of 2 times. Next, this mixed powder was placed in an alumina crucible (model number: 1-7745-07) with a capacity of 30 mL, and this crucible was placed in a tabletop vacuum / gas displacement furnace (“KDF75” from Denken Hydental). . Then, the temperature was raised from room temperature to 1000 ° C. at a constant rate of temperature over 10 hours in a nitrogen stream at a constant temperature rise rate, held at this temperature for 4 hours, and then allowed to cool naturally to room temperature. In this way, a lithium molybdenum composite oxide represented by the composition formula LiMoO ₂ was produced.

[Examples 1 to 4] (Synthesis of lithium molybdenum phosphorus composite oxide)
The lithium-molybdenum composite oxide obtained in Synthesis Example 1 and lithium phosphate (Li ₃ PO ₄ ) (manufactured by Nacalai Tesque) have a Mo: P molar ratio of 90:10 (Example 1), 80:20 ( Example 2), 70:30 (Example 3), and 60:40 (Example 4), and the total mass of these oxides was weighed to be about 4.5 g. . These were put into a tungsten carbide pot having an internal volume of 80 mL containing 250 g (about 250 pieces) of tungsten carbide balls having a diameter of 5 mm, and were covered in a glove box maintained in an argon atmosphere. This was set on a planetary ball mill ("Pulverisete 5" manufactured by FRITSCH), mixed for 12 minutes at a revolution speed of 400 rpm, and then put into a rest for 3 minutes, a total of 16 times. Thus, the composition formula (1-y) LiMoO ₂ -yLi ₃ PO ₄ , that is, Li _{1 + 2y} Mo _1-y P _y O _{2 + 2y} (y = 0.1, 0.2, 0.3, 0.4) Lithium molybdenum phosphorus composite oxide represented by

[Example 5] (Synthesis of lithium molybdenum carbon composite oxide)
Except that the lithium molybdenum composite oxide obtained in Synthesis Example 1 and lithium carbonate (Li ₂ CO ₃ ) (manufactured by Nacalai Tesque) were weighed so that the Mo: C molar ratio was 80:20. Is a lithium molybdenum carbon composite represented by the composition formula 0.8LiMoO ₂ -0.2Li ₂ CO ₃ , that is, Li _1.2 Mo _0.8 C _0.2 O _2.2 , in the same manner as in Example 1. An oxide was produced.

[Comparative Example 2] (Synthesis of lithium molybdenum composite oxide)
The Mo: P molar ratio was set to 100: 0, this was set in a planetary ball mill ("Pulverisete 5" from FRISCH), mixed for 12 minutes at a revolution speed of 400 rpm, and then put into a rest for 3 minutes 8 times A lithium molybdenum composite oxide represented by the composition formula LiMoO ₂ was produced in the same manner as in Example 1 except for the repetition.

[Comparative Example 3] (lithium phosphate)
The same process as in Example 1 was performed except that the molar ratio of Mo: P was set to 0: 100, that is, only lithium phosphate (Li ₃ PO ₄ ) was used as a raw material.

[Synthesis Example 2] (Synthesis of lithium germanium composite oxide)
Lithium carbonate (Li ₂ CO ₃ ) (manufactured by Nacalai Tesque) and germanium oxide (GeO ₂ ) (manufactured by Koyo Chemical Co., Ltd.) were weighed so that the molar ratio of Li: Ge was 2: 1. These were put into a zirconia pot having an internal volume of 80 mL containing 90 g (about 250 pieces) of zirconia balls having a diameter of 5 mm. An additional 10 mL of ethanol was added to the pot and the lid was covered. This was set on a planetary ball mill ("Pulverisete 5" manufactured by FRITSCH), mixed for 9 minutes at a revolution speed of 300 rpm, and then put into a pause for 1 minute, a total of 6 times. This mixture was dried with an oven at 80 ° C. for 3 hours or longer to obtain a mixed powder. This mixed powder was placed in an alumina crucible (model number: 1-7745-07) having a capacity of 30 mL, and this crucible was placed in a tabletop vacuum / gas displacement furnace (“KDF75” manufactured by Denken Haydental). Next, the temperature was raised from normal temperature to 950 ° C. over 10 hours at a constant heating rate in an air stream, kept at this temperature for 4 hours, and then allowed to cool naturally to room temperature. In this way, a lithium germanium composite oxide represented by the composition formula Li ₂ GeO ₃ was produced.

[Example 6] (Synthesis of lithium molybdenum germanium composite oxide)
Except that the lithium molybdenum composite oxide obtained in Synthesis Example 1 and the lithium germanium composite oxide obtained in Synthesis Example 2 were weighed so that the molar ratio of Mo: Ge was 80:20. In the same manner as in Example 1, lithium molybdenum germanium composite oxidation represented by the composition formula 0.8LiMoO ₂ -0.2Li ₂ GeO ₃ , that is, Li _1.2 Mo _0.8 Ge _0.2 O _2.2. A product was made.

[Synthesis Example 3] (Synthesis of lithium cobalt composite oxide)
Lithium carbonate (Li ₂ CO ₃ ) (manufactured by Nacalai Tesque) and cobalt oxide (Co ₃ O ₄ ) (manufactured by Koyo Chemical Co., Ltd.) were weighed so that the molar ratio of Li: Co was 1: 1. The composition formula LiCoO ₂ was the same as in Synthesis Example 2 except that the temperature was raised from room temperature to 650 ° C. at a constant rate of temperature over 10 hours and maintained at this temperature for 4 hours. The lithium cobalt complex oxide represented by this was produced.

[Comparative Example 4] (Synthesis of lithium molybdenum cobalt composite oxide)
Except that the lithium molybdenum composite oxide obtained in Synthesis Example 1 and the lithium cobalt composite oxide obtained in Synthesis Example 3 were weighed so that the molar ratio of Mo: Co was 80:20. In the same manner as in Example 1, a lithium molybdenum cobalt composite oxide represented by the composition formula 0.8LiMoO ₂ -0.2LiCoO ₂ , that is, LiMo _0.8 Co _0.2 O ₂ was produced.

[Analysis of complex oxides]
The composite oxides obtained in Examples 1 to 6 and Comparative Examples 1 to 4 were analyzed by the following method. Powder X-ray diffraction measurement was carried out using an X-ray diffractometer (“MiniFlex II” from Rigaku). The radiation source was CuKα ray, the tube voltage was 30 kV, the tube current was 15 mA, and the diffracted X-ray was detected by a high-speed one-dimensional detector (model number: D / teX Ultra 2) through a Kβ filter having a thickness of 30 μm. The sampling width was 0.01 °, the scanning speed was 5 ° / min, the divergence slit width was 0.625 °, the light receiving slit width was 13 mm (OPEN), and the scattering slit width was 8 mm. The X-ray diffraction patterns of the composite oxides of Examples 1 to 4 and Comparative Examples 2 and 3 are shown in FIG. 3, and the X-ray diffraction patterns of the composite oxides of Examples 5 and 6 and Comparative Example 4 are shown in FIG. The obtained X-ray diffraction data was subjected to Rietveld analysis using the above-mentioned “Rietan 2000” program.

  In the Rietveld analysis of the composite oxide of Example 1, the Pearson VII function was used as a function representing the profile, and a NaCl-type crystal structure model as shown in Table 1 was used. The refined crystal structure model is shown in Table 1, and the calculated value, the actually measured value, and a graph showing the difference between them are shown in FIG. According to the crystal structure model shown in Table 1, the difference between the calculated value and the actually measured value was sufficiently small as shown in FIG. The reliability factors were Rwp = 4.73%, RI = 1.55%, and RF = 0.82%, respectively, indicating that the difference between the calculated value and the actually measured value was sufficiently small. From these results, it was estimated that the crystal structure model shown in Table 1 was appropriate.

In the Rietveld analysis of each composite oxide of Examples 2 and 3, the Pearson VII function was used as a function representing the profile, the α-NaFeO ₂ type crystal structure model (first phase) and NaCl as shown in Table 2 A model in which two phases of the crystal structure model (second phase) of the mold coexist was used. As an example, a refined crystal structure model as a result of Rietveld analysis of the lithium molybdenum phosphorous oxide of Example 2 is shown in Table 2, and a calculated value, an actual measurement value, and a graph showing the difference between them are shown in FIG. According to the crystal structure model shown in Table 2, the difference between the calculated value and the actually measured value was sufficiently small as shown in FIG. The reliability factors are Rwp = 4.84%, first phase RI = 1.14%, RF = 0.68%, second phase RI = 1.54%, RF = 0.82%. Yes, it was shown that the difference between the calculated value and the measured value was sufficiently small. From these results, it was estimated that the crystal structure model shown in Table 2 was appropriate.

In addition, Rietveld analysis of the composite oxide of Example 2 was performed using a model different from the above. A Pearson VII function was used as a function representing a profile, and an α-NaFeO ₂ type crystal structure model having only one phase as shown in Table 3 was used. The refined crystal structure model is shown in Table 3, and the calculated value, the actual measurement value, and a graph showing the difference between them are shown in FIG. The reliability factor was Rwp = 5.67%, which was worse than the result Rwp = 4.84%. This is considered to be caused by poor fitting of peaks particularly at around 38 ° and around 64 °. These peaks can be fitted as peaks of the diffraction indices 111 and 220 of the space group Fm-3m (NaCl type structure). From the above, it is shown that the model in which two phases of α-NaFeO ₂ type crystal structure model (first phase) and NaCl type crystal structure model (second phase) coexist as shown in Table 2 is more appropriate. It was done.

In the Rietveld analysis of the complex oxide of Example 5, the Pearson VII function was used as a function representing the profile, the α-NaFeO ₂ type crystal structure model (first phase) and the NaCl type crystal as shown in Table 4 A model in which two phases of the structural model (second phase) coexist was used. As a result of Rietveld analysis of the lithium molybdenum carbon oxide according to Example 5, a refined crystal structure model is shown in Table 4, and calculated values, measured values, and a graph representing the difference between them are shown in FIG. According to the crystal structure model shown in Table 4, the difference between the calculated value and the actually measured value was sufficiently small as shown in FIG. The reliability factors are Rwp = 4.75%, RI of the first phase = 1.12%, RF = 0.61%, RI of the second phase = 1.05%, and RF = 0.61%. Yes, it was shown that the difference between the calculated value and the measured value was sufficiently small. From these results, it was estimated that the crystal structure model shown in Table 4 was appropriate.

As a result of analysis of each composite oxide of Examples and Comparative Examples in addition to the above-described Examples 1, 2, and 5, the space groups that can be assigned are as follows.
Examples 1 and 6 and Comparative Examples 2 and 4: Space group Fm-3m
Examples 2 and 5: Space group R-3m and space group Fm-3m (two-phase coexistence)
Examples 3 and 4: space group R-3m, space group Fm-3m, and Li ₃ PO ₄ (3 phase coexistence)
Comparative Example 1: Space group C2 / m or R-3m
Comparative Example _3: Li ₃ PO 4 (PDF number 00-025-1030)

  From the above analysis, it was found that in Examples 1 to 6 and Comparative Examples 2 and 4, the mechanochemical reaction proceeded in the course of treatment with the planetary ball mill. On the other hand, in Comparative Example 3, the mechanochemical reaction did not proceed in the course of the treatment by the planetary ball mill, and only the particles were pulverized.

[Production of nonaqueous electrolyte storage element (test battery)]
Using each composite oxide obtained in Examples 1 to 4 and 6 and Comparative Examples 3 to 4 as a positive electrode active material, positive electrodes were produced in the following manner. 2.275 g of each synthesized composite oxide powder and 0.700 g of acetylene black (AB) were weighed. These were put into a zirconia pot having an internal volume of 80 mL containing 90 g (about 250 pieces) of zirconia balls having a diameter of 5 mm. A further 10 mL of acetone was added to the pot, and the pot was covered in a glove box maintained in an argon atmosphere. This was set on a planetary ball mill ("Pulverisete 5" manufactured by FRITSCH), mixed for 12 minutes at a revolution speed of 300 rpm, and then put into a 3-minute pause for 48 times in total. This mixture was dried with a dryer at 75 ° C. for 3 hours or more to prepare a mixed powder. 2.04 g of this mixed powder, 12 mass% N-methylpyrrolidone (NMP) solution of PVDF, and NMP were put in a predetermined plastic container, and the lid was covered in a glove box maintained in an argon atmosphere. This was set in a stirring defoaming device (“Niwataro Awatori” manufactured by Shinky Corporation) and sufficiently kneaded at 2000 rpm to prepare a slurry using N-methylpyrrolidone (NMP) as a dispersion medium. The mass ratio of the active material, AB and PVDF in the slurry is 65:20:15. This slurry was applied to one side of a 20 μm thick aluminum foil substrate. This was dried on an 80 ° C. hot plate for 60 minutes to evaporate the dispersion medium, and then subjected to roll press to obtain a positive electrode.

  For Example 5, a positive electrode was obtained in the same manner as described above, except that the operation of putting a rest for 1 minute after mixing at a revolution speed of 300 rpm for 9 minutes was repeated a total of 6 times.

  Moreover, each composite oxide obtained in Comparative Examples 1 and 2 was used as a positive electrode active material, and a positive electrode was produced in the following manner. 2.275 g of each synthesized composite oxide powder and 0.525 g of acetylene black (AB) were weighed. These were put into a zirconia pot having an internal volume of 80 mL containing 90 g (about 250 pieces) of zirconia balls having a diameter of 5 mm. A further 10 mL of acetone was added to the pot, and the pot was covered in a glove box maintained in an argon atmosphere. This was set in a planetary ball mill ("Pulverisete 5" manufactured by FRITSCH), mixed for 12 minutes at a revolution speed of 240 rpm, and then put into a rest for 3 minutes, 48 times in total. This mixture was dried with a dryer at 75 ° C. for 3 hours or more to prepare a mixed powder. 1.6 g of the mixed powder, 0.1 g of AB, 12% by mass N-methylpyrrolidone (NMP) solution of PVDF and NMP were put in a predetermined plastic container, and the lid was covered in a glove box maintaining an argon atmosphere. This was set in a stirring defoaming device (“Niwataro Awatori” manufactured by Shinky Corporation) and sufficiently kneaded at 2000 rpm to prepare a slurry using N-methylpyrrolidone (NMP) as a dispersion medium. The mass ratio of the active material, AB and PVDF in the slurry is 65:20:15. This slurry was applied to one side of a 20 μm thick aluminum foil substrate. This was dried on an 80 ° C. hot plate for 60 minutes to evaporate the dispersion medium, and then subjected to roll press to obtain a positive electrode.

A test battery was assembled using each of the positive electrodes as a working electrode, and the behavior as a positive electrode was evaluated. For the purpose of accurately observing the single behavior, a counter electrode in which metallic lithium was adhered to a nickel foil current collector was used. Here, a sufficient amount of metallic lithium was arranged so that the capacity of the test battery was not limited by the counter electrode. A solution obtained by dissolving LiPF ₆ as an electrolyte in a mixed solvent of ethylene carbonate (EC) / ethyl methyl carbonate (EMC) / dimethyl carbonate (DMC) in a volume ratio of 6: 7: 7 so that the concentration becomes 1 mol / L. Was used. As the separator, a polypropylene microporous film whose surface was modified with polyacrylate was used. A metal resin composite film made of polyethylene terephthalate (15 μm) / aluminum foil (50 μm) / metal-adhesive polypropylene film (50 μm) is used for the exterior body, and the electrodes are exposed so that the open ends of the positive electrode terminal and the negative electrode terminal are exposed to the outside. Stowed. Subsequently, the fusion allowance in which the inner surfaces of the metal resin composite film face each other was hermetically sealed except for a portion serving as a liquid injection hole, and the liquid injection hole was sealed after pouring the electrolytic solution.

[Charge / discharge test]
The obtained nonaqueous electrolyte electricity storage element was charged / discharged in a thermostat set at 25 ° C. Charging was constant current constant voltage (CCCV) charging, and discharging was constant current (CC) discharging. The constant current value for charging and discharging was 20 mA / g with respect to the mass of the positive electrode active material contained in the positive electrode plate. The charge upper limit voltage and the discharge end voltage were 4.4 V and 1.2 V, respectively. The charge termination conditions were the time when the charging current was attenuated to 2 mA / g or the time when 3 hours had passed since the charging upper limit voltage was reached. In each cycle, a pause time of 10 minutes was set after charging and discharging. This cycle was carried out 8 cycles. In this test, voltage control was performed between the working electrode and the counter electrode. However, since the dissolution / deposition reaction resistance of metallic lithium at the counter electrode was extremely low, metal lithium was used as the voltage between terminals during charging and discharging. It can be regarded as being equal to the potential of the working electrode with respect to the reference electrode. Table 5 shows the discharge capacity at the eighth cycle in this charge / discharge cycle test. Further, the ratio of the discharge capacity at the eighth cycle to the discharge capacity at the third cycle was determined as “capacity maintenance ratio (%)”. This capacity retention rate is also shown in Table 5. Table 5 also shows a method for synthesizing each composite oxide. In the table, “MC method” indicates a mechanochemical method. Moreover, the discharge curve of the 3rd cycle of Example 1 and the 8th cycle is shown in FIG.

  As shown in Table 5, it can be seen that the nonaqueous electrolyte storage elements of Examples 1 to 6 have a high capacity retention rate of 90% or more. In addition, the nonaqueous electrolyte storage elements of Examples 1 to 3, 5 and 6 have a discharge capacity at the eighth cycle of 200 mAh / g or more, and have a sufficient discharge capacity.

On the other hand, Comparative Example 1 using LiMoO ₂ obtained by firing has a small discharge capacity and a low capacity retention rate. In Comparative Example 2 using LiMoO ₂ subjected to the MC method, the discharge capacity is larger than that in Comparative Example 1, but the capacity retention rate is low. Further, Comparative Example 3 using Li ₃ PO ₄ has a very small discharge capacity and a low capacity retention rate.

  Further, Comparative Example 4 in which Co is introduced into lithium molybdenum oxide has a low capacity retention rate. This is presumably because deterioration occurs because Co is oxidized and reduced during charge and discharge. On the other hand, in Examples 1 to 6, in which an element such as P, C, and Ge that is difficult to be oxidized / reduced during charging / discharging and that has a high covalent bonding property with oxygen is introduced into lithium molybdenum oxide, deterioration hardly occurs during charging / discharging. It is estimated that the capacity maintenance rate is increasing.

  The present invention can be applied to electronic devices such as personal computers and communication terminals, non-aqueous electrolyte secondary batteries used as a power source for automobiles, and a positive electrode and a positive electrode active material provided therein.

DESCRIPTION OF SYMBOLS 1 Nonaqueous electrolyte electrical storage element 2 Electrode body 3 Container 4 Positive electrode terminal 4 'Positive electrode lead 5 Negative electrode terminal 5' Negative electrode lead 20 The electrical storage unit 30 The electrical storage apparatus

Claims (7)

Including lithium, molybdenum and element (A),
The element (A) is boron, carbon, nitrogen, fluorine, silicon, phosphorus, sulfur, chlorine, zinc, gallium, germanium, arsenic, selenium, bromine, tin, antimony, tellurium, iodine or a combination thereof.
The complex oxide whose content of the said element (A) with respect to the total content of the said molybdenum and the said element (A) is 1 mol% or more and less than 50 mol%. The composite oxide according to claim 1 represented by the following formula (1).
Li _{1 + x} Mo _1-y A _y O _z (1)
(In the formula (1), A is B, C, N, F, Si, P, S, Cl, Zn, Ga, Ge, As, Se, Br, Sn, Sb, Te, I, or a combination thereof. (0 ≦ x, 0.01 ≦ y <0.5, 0 <z)   The composite oxide according to claim 1 or 2, comprising a crystal structure that can be assigned to the space group Fm-3m.   A positive electrode active material for a non-aqueous electrolyte storage element, comprising the composite oxide according to claim 1, claim 2 or claim 3.   The positive electrode for nonaqueous electrolyte electrical storage elements which has the positive electrode active material of Claim 4.   A nonaqueous electrolyte storage element having the positive electrode according to claim 5. Treating one or more oxides by mechanochemical method;
The one or more oxides include lithium, molybdenum, and element (A),
Compound oxide in which the element (A) is boron, carbon, nitrogen, fluorine, silicon, phosphorus, sulfur, chlorine, zinc, gallium, germanium, arsenic, selenium, bromine, tin, antimony, tellurium, iodine, or a combination thereof Manufacturing method.

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