JP6680249B2 - Negative electrode active material, negative electrode, non-aqueous electrolyte storage element, and method for producing negative electrode active material - Google Patents

Description

  The present invention relates to a negative electrode active material, a negative electrode, a non-aqueous electrolyte storage element, and a method for manufacturing a negative electrode active material.

  Non-aqueous electrolyte secondary batteries typified by lithium ion secondary batteries are widely used in electronic devices such as personal computers and communication terminals, automobiles, etc. because of their high energy density. The non-aqueous electrolyte secondary battery generally has a pair of electrodes electrically isolated by a separator and a non-aqueous electrolyte interposed between the electrodes, and transfers ions between both electrodes. It is configured to be charged and discharged. In addition, capacitors such as lithium ion capacitors and electric double layer capacitors have been widely used as non-aqueous electrolyte storage elements other than non-aqueous electrolyte secondary batteries.

A carbon material such as graphite, a metal oxide, or the like is used as an active material included in the negative electrode of the nonaqueous electrolyte storage element. Various active materials are being developed for increasing the capacity of power storage devices, and oxides containing molybdenum, for example, are being studied as negative electrode active materials. Specifically, in Patent Document 1 below, Li _2−x MoO ₄ (−0.5 ≦ x ≦ 0.5) and Li _4−y Mo ₅ O ₁₇ (−1 ≦ y ≦ 1) are negative electrode active materials. Considered as a substance. Further, in Non-Patent Document 1 below, a thin-film electrode of nano-particled MoO ₃ negative electrode active material is studied.

JP, 2010-232029, A

Natsha A. Chernova, Megan Roppolo, Anne C .; Dillon, M .; Stanley Whittingham, "J. Mater. Chem.", 2009, 19, p2526-2552.

  However, even in the non-aqueous electrolyte storage element using the oxide containing each molybdenum as a negative electrode active material, the discharge capacity is large and the discharge capacity maintenance ratio is high, and the discharge capacity and the maintenance ratio are sufficiently compatible. Is difficult. Further, in the thin film electrode described in Non-Patent Document 1, the ratio of the active material to the negative electrode base material (current collector) is small, and it is not possible to fill the limited space of the battery with a sufficient amount of the active material. Therefore, it cannot contribute to increasing the capacity of the battery.

  The present invention has been made based on the above circumstances, and an object thereof, when used for a non-aqueous electrolyte storage element, is that the non-aqueous electrolyte storage element has a sufficient discharge capacity and a high discharge capacity retention rate. It is to provide a negative electrode active material which can also have the above, a negative electrode having the negative electrode active material, a non-aqueous electrolyte storage element having the negative electrode, and a method for producing the negative electrode active material.

  The negative electrode active material according to one embodiment of the present invention made to solve the above problems contains lithium, molybdenum, and an element (A), and the element (A) is boron, carbon, nitrogen, fluorine, silicon, or phosphorus. It is a negative electrode active material for a non-aqueous electrolyte electricity storage device containing a complex oxide which is sulfur, chlorine, gallium, arsenic, bromine, tellurium, iodine or a combination thereof.

  A negative electrode according to another aspect of the present invention is a negative electrode for a non-aqueous electrolyte power storage device including the negative electrode active material.

  A non-aqueous electrolyte power storage element according to another aspect of the present invention is a non-aqueous electrolyte power storage element having the negative electrode.

  A method for producing a negative electrode active material according to another aspect of the present invention comprises treating a plurality of types of oxides by a mechanochemical method, wherein the plurality of types of oxides contain lithium, molybdenum and the element (A). Including, the element (A) is boron, carbon, nitrogen, fluorine, silicon, phosphorus, sulfur, chlorine, gallium, arsenic, bromine, tellurium, iodine or a combination thereof, a negative electrode active material for a non-aqueous electrolyte storage element. Is a manufacturing method.

  According to the present invention, when used in a non-aqueous electrolyte power storage element, the non-aqueous electrolyte power storage element can have both a sufficient discharge capacity and a high discharge capacity retention rate, and a negative electrode having this negative electrode active material. It is possible to provide a non-aqueous electrolyte storage element having this negative electrode, and a method for producing the above negative electrode active material.

FIG. 1 is an external perspective view showing a non-aqueous electrolyte storage element according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing a power storage device configured by collecting a plurality of nonaqueous electrolyte power storage elements according to an embodiment of the present invention. FIG. 3 is an X-ray diffraction diagram of the composite oxides (negative electrode active material) of Examples 1 to 4 and Comparative Examples 2 and 6. FIG. 4 is an X-ray diffraction diagram of the composite oxides (negative electrode active material) of Example 5 and Comparative Example 7. FIG. 5 is a graph showing calculated values, measured values, and differences in Rietveld analysis for the composite oxide (negative electrode active material) of Example 1. FIG. 6 is a graph showing calculated values (two-phase coexistence model) in Rietveld analysis for the composite oxide (negative electrode active material) of Example 2, measured values, and differences between these. FIG. 7 is a graph showing calculated values (one-phase model) in Rietveld analysis for the composite oxide (negative electrode active material) of Example 2, measured values, and differences between these. FIG. 8 is a graph showing calculated values, measured values, and differences in Rietveld analysis for the composite oxide (negative electrode active material) of Example 5. FIG. 9 is a discharge curve (0.2-3.0 V) of the nonaqueous electrolyte storage element of Example 5. FIG. 10 is a discharge curve (0.1-3.0 V) of the non-aqueous electrolyte storage element of Example 2.

  The negative electrode active material according to one embodiment of the present invention contains lithium, molybdenum and element (A), and the element (A) is boron, carbon, nitrogen, fluorine, silicon, phosphorus, sulfur, chlorine, gallium, arsenic. It is a negative electrode active material for a non-aqueous electrolyte electricity storage device, which contains a complex oxide of bromine, tellurium, iodine or a combination thereof.

Since the negative electrode active material contains the composite oxide, it is possible to increase the discharge capacity retention rate of the non-aqueous electrolyte storage element. The reason for this is not clear, but the following reasons are presumed. Usually, when an oxide containing molybdenum is used for the negative electrode active material, the oxide is likely to deteriorate due to stress due to expansion and contraction accompanying the redox reaction of molybdenum. On the other hand, the element (A) is an element having a strong covalent bond with oxygen and is in a normal potential range (for example, 0.2 V (vs. Li ^/ Li ⁺ ) or more when used as a negative electrode active material. It is an element in which a redox reaction hardly occurs at 0.0 V (vs. Li / Li ⁺ ) or less). All of the above elements (A) have an electronegativity of Allred-Rochow of 1.7 or more, and thus have high covalent bondability with oxygen. In the composite oxide containing such an element (A), an AOx unit is incorporated into the structure, and this unit is unlikely to change its structure during the oxidation-reduction reaction of molybdenum during charge and discharge. Therefore, the stress is alleviated, and the progress of deterioration is suppressed, so that it is presumed that the discharge capacity retention rate is increased. Further, the negative electrode active material can exhibit a good discharge capacity retention rate without being used as a thin film electrode. Furthermore, the non-aqueous electrolyte storage element using the negative electrode active material also has a sufficient discharge capacity. The reason for this is not clear, but it is presumed that the crystal structure changed in the course of the mechanochemical reaction, and lithium ions were easily inserted into and desorbed from the space surrounded by oxygen in the crystal structure. In addition, since the composite oxide contains an element (A) having a high covalent bond with oxygen, it has excellent thermal stability, and when the negative electrode active material is used for the negative electrode of the non-aqueous electrolyte storage element. It excels in safety and so on. In the present specification, the composite oxide acts as a negative electrode active material, and “recharges” a reduction reaction in which lithium ions and the like are occluded with respect to the negative electrode active material, and oxidizes lithium ions and the like to be released The reaction is called “discharge”.

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, Ga, As, Br, Te, I, or a combination thereof. 0 ≦ x, 0 <y < 1, 0 <z.)

  When the composite oxide has the composition represented by the formula (1), the discharge capacity and the discharge capacity retention rate of the non-aqueous electrolyte storage element can be improved.

  The content of the element (A) with respect to the total content of the molybdenum and the element (A) is preferably 1 mol% or more and less than 50 mol%. By setting the content of the element (A) within the above range, the ratio of molybdenum to the element (A) becomes a suitable balance, and the discharge capacity and the discharge capacity retention rate of the non-aqueous electrolyte storage element are well balanced and better. be able to.

  It is preferable that the composite oxide include a crystal structure that can be assigned to the space group Fm-3m. When the composite oxide contains the crystal structure, the discharge capacity and discharge capacity retention rate of the non-aqueous electrolyte storage element can be improved. The reason for this is not clear, but it is presumed that the above-mentioned crystal structure is a structure that can further alleviate the stress during the above-described oxidation-reduction reaction of molybdenum.

  A negative electrode according to an embodiment of the present invention is a negative electrode for a non-aqueous electrolyte power storage device having the negative electrode active material. Since the negative electrode has the negative electrode active material, when used in a non-aqueous electrolyte power storage element, the non-aqueous electrolyte power storage element can have both a sufficient discharge capacity and a high discharge capacity retention rate.

  A non-aqueous electrolyte storage element according to an embodiment of the present invention is a non-aqueous electrolyte storage element having the negative electrode. The non-aqueous electrolyte storage element has both a sufficient discharge capacity and a high discharge capacity retention rate.

  A method for producing a negative electrode active material according to an embodiment of the present invention comprises treating one or more oxides by a mechanochemical method, wherein the one or more oxides are lithium, molybdenum and an element ( A), and the above element (A) is boron, carbon, nitrogen, fluorine, silicon, phosphorus, sulfur, chlorine, gallium, arsenic, bromine, tellurium, iodine, or a combination thereof for a non-aqueous electrolyte storage element It is a manufacturing method of a negative electrode active material. According to the manufacturing method, it is possible to manufacture a negative electrode active material which, when used in a non-aqueous electrolyte power storage element, allows the non-aqueous electrolyte power storage element to have both a sufficient discharge capacity and a high discharge capacity retention rate. . Further, according to the manufacturing method, a negative electrode active material that is easy to synthesize and has few impurities can be obtained.

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

<Negative electrode active material>
The negative electrode active material according to one embodiment of the present invention contains a composite oxide containing lithium (Li), molybdenum (Mo) and the element (A).

  The element (A) is boron (B), carbon (C), nitrogen (N), fluorine (F), silicon (Si), phosphorus (P), sulfur (S), chlorine (Cl), gallium (Ga). ), Arsenic (As), bromine (Br), tellurium (Te), iodine (I), or a combination thereof. The above element (A) may be only one type, or may be two or more types. Among the above elements (A), boron, carbon, nitrogen, fluorine, phosphorus, sulfur, chlorine, arsenic, bromine, tellurium and iodine, which have an electronegativity of 2.0 or more for all red and roach, are preferable, and the electronegativity is the above. Are more preferably 2.1 or more, carbon, nitrogen, fluorine, phosphorus, sulfur, chlorine, arsenic, bromine and iodine are more preferable. Also, boron, carbon, nitrogen, silicon, phosphorus and sulfur are preferable, and carbon and phosphorus are more preferable. By using these elements, it is possible to further improve the discharge capacity and the discharge capacity retention rate of the non-aqueous electrolyte storage element. Further, the production cost of the complex oxide can be suppressed by using these relatively easily available elements. Further, as the element (A), boron, carbon, nitrogen, fluorine, silicon, phosphorus, sulfur, chlorine, gallium, bromine, tellurium and iodine are also preferable. By using these elements with low toxicity, it is possible to enhance safety.

  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 not particularly limited, but 1 mol% is preferable, 5 mol% is more preferable, and 10 mol% is more preferable. Mol% is more preferred, and in some cases 15 mol% is even more preferred. By setting the content of the element (A) to be the above lower limit or more, the discharge capacity retention rate can be increased.

  The upper limit of the content of the element (A) with respect to the total content of the molybdenum and the element (A) is not particularly limited, but the content is preferably less than 50 mol%. The upper limit of this content is more preferably 45 mol%, sometimes 35 mol%, more preferably 25 mol%, and even more preferably 15 mol%. By setting the content of the element (A) to be the above upper limit or less, the discharge capacity can be increased.

  The content of lithium in the composite oxide is not particularly limited. The composition ratio of lithium fluctuates significantly due to charge and discharge, the composition ratio of lithium may be higher than that during synthesis at the end of discharge, and the lithium raw material may be added in excess of the theoretical composition ratio during synthesis. Therefore, the content of lithium in the composite oxide does not significantly affect the performance as the negative 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 the oxide may be oxygen-deficient or oxygen-rich, it may not be 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 composite oxide may contain elements other than lithium, molybdenum, the element (A), and oxygen within a range that does not affect the effects of the present invention. Examples of such other optional elements include metallic elements such as sodium, potassium, magnesium, calcium and indium. As the upper limit of the content of these optional elements, 50 mol% is preferable, 20 mol% is more preferable, 10 mol% is further preferable, and 1 mol% is relative to the total content of molybdenum and element (A). Is more preferable, and 0.1 mol% is particularly preferable. This optional element may not be contained substantially.

  Since the above complex oxide does not contain chromium as an essential component, there are few industrial usage restrictions. That is, the composite oxide may have a composition that does not substantially contain chromium. When the composite oxide does not substantially contain chromium, the safety is higher than that of the composite oxide containing chromium. Here, "not substantially containing chromium" means that chromium is not intentionally added. The content of chromium in the composite oxide or the negative electrode active material is preferably 1,000 ppm (0.1% by mass) or less. It is also preferable that the content of chromium 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 composite oxide or the negative electrode active material is a value measured by an ICP emission spectroscopy analyzer.

The complex oxide can be 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, Ga, As, Br, Te, I, or a combination thereof. 0 ≦ x, 0 <y <1, 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) represents 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 0.01, more preferably 0.05, even more preferably 0.1, and even more preferably 0.15. Further, y is preferably less than 0.5. Furthermore, the upper limit of y is preferably 0.45, more preferably 0.35, sometimes more preferably 0.25, and sometimes more preferably 0.15.

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

The composite 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 formulas (1-1) and (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, etc.) as raw materials in a molar ratio of 1-y: y. Here, in comparison with the formula (1) and the formula (1-1), and considering that lithium and oxygen are not clearly determined as described above, 0.9 ≦ (1 + x) / in the formula (1) It may be (1 + 2y) ≦ 1.1 and 0.9 ≦ z / (2 + 2y) ≦ 1.1.

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

  The complex oxide preferably contains 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 composite oxide may have a crystal structure belonging to the space group Fm-3m. However, the crystal structure may not be maintained due to repeated charging and discharging. Therefore, it is preferable that the crystal structure before charging / discharging belongs to the above space group. It should be noted that "-3" in the space group "Fm-3m" represents the target element of the three-fold anti-axis, and should be originally written by adding a bar "-" over "3". The composite oxide may have a crystal structure other than the space group Fm-3m, such as the space group R-3m. The composite oxide may be a crystal body having a plurality of crystal structures. As a minimum of the content rate of the crystal structure which can be assigned to space group Fm-3m in the compound oxide, 5 mass% is preferred, 10 mass% is more preferred, and 20 mass% is still more preferred. The upper limit of this content ratio may be 100% by mass.

  The X-ray diffraction measurement of the composite oxide is carried out by powder X-ray diffraction measurement using an X-ray diffractometer (“MiniFlex II” manufactured by Rigaku Co.) with a CuKα ray as a radiation source, a tube voltage of 30 kV, and a tube current of 15 mA. . At this time, the diffracted X-rays pass through a Kβ filter having a thickness of 30 μm and are detected by a high-speed one-dimensional detector (D / teX Ultra 2). The sampling width is 0.01 °, the scan 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 the comprehensive powder X-ray analysis software "PDXL" (manufactured by Rigaku).

  The negative electrode active material may be formed only from the composite oxide, but may include other negative electrode active materials. Other negative electrode active materials include, for example, metals such as Si and Sn or metalloids; metal oxides such as Si oxide and Sn oxides or metalloid oxides; polyphosphoric acid compounds; graphite, amorphous carbon. Examples thereof include carbon materials such as (graphitizable carbon or non-graphitizable carbon). The negative electrode active material may contain, for example, a composite oxide containing lithium and the element (A).

  As a minimum of the content of the above-mentioned compound oxide in the anode active material, 50 mass% is preferred, 70 mass% is more preferred, and 90 mass% is still more preferred. By increasing the content rate of the complex oxide, the discharge capacity and the discharge capacity maintenance rate of the non-aqueous electrolyte storage element can be improved.

<Method for producing negative electrode active material>
The manufacturing method of the negative electrode active material is not particularly limited, but the following manufacturing method is preferable. That is, the method for producing a negative electrode active material according to an embodiment of the present invention comprises treating one or more oxides by a mechanochemical method, and the one or more oxides are lithium, molybdenum and Production of a negative electrode active material containing the element (A), wherein the element (A) is boron, carbon, nitrogen, fluorine, silicon, phosphorus, sulfur, chlorine, gallium, arsenic, bromine, tellurium, iodine or a combination thereof. Is the way.

  According to this 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 the mechanochemical method. When the negative electrode active material is a mixture of the composite oxide and another negative electrode active material, for example, the composite oxide obtained by the above treatment and another negative electrode active material may be mixed by a known method. Thus, the negative electrode active material as a mixture can be obtained. Moreover, in the said manufacturing method, the composite oxide of a desired composition ratio can be obtained by adjusting the mixing ratio of several types of oxides.

  The mechanochemical method (also referred to as mechanochemical treatment) is a synthetic method utilizing mechanochemical reaction. The mechanochemical reaction refers to a chemical reaction such as a crystallization reaction, a solid solution reaction or a phase transition reaction which utilizes 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 a crushing / dispersing machine such as a ball mill, a bead mill, a vibration mill, a turbo mill, a mechanofusion, and a disc mill. Of these, a ball mill is preferable.

  As the raw material oxide, three or more kinds of oxides including an oxide containing lithium, an oxide containing molybdenum and an oxide containing the element (A) can be used, but an oxide containing lithium and molybdenum is used. It is preferable to use a substance and an oxide containing lithium and the element (A). An oxide containing molybdenum and the element (A) can also be used. Note that in the case of using a plurality of kinds of oxides, lithium, molybdenum, and the element (A) may be contained as a whole in the plurality of kinds of oxides.

Examples of oxides 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 , LiGaO ₂ , and Li ₅ GaO. ₄ , 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 and the} like can be mentioned.

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

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

  These raw material oxides are usually powdery, and the powdery oxide is subjected to treatment by the mechanochemical method. This treatment can be carried out in an inert gas atmosphere such as argon or in an active gas atmosphere, but it is preferably carried out in an inert gas atmosphere. The composite oxide obtained through such treatment is usually in powder form.

<Negative electrode>
A negative electrode according to an embodiment of the present invention is a negative electrode for a non-aqueous electrolyte power storage device having the negative electrode active material.

  A negative electrode according to an embodiment of the present invention includes a negative electrode base material and a negative electrode composite material layer disposed on the negative electrode base material directly or via an intermediate layer.

  The negative electrode base material has conductivity. As the material of the negative electrode base material, a metal such as copper, nickel, stainless steel, nickel plated steel or an alloy thereof is used, and copper or a copper alloy is preferable. In addition, examples of the form of forming the negative electrode base material include a foil and a vapor deposition film, and the foil is preferable from the viewpoint of cost. That is, copper foil is preferable as the negative electrode base material. Examples of the copper foil include rolled copper foil and electrolytic copper foil.

The intermediate layer is a coating layer on the surface of the negative electrode base material, and contains conductive particles such as carbon particles to reduce the contact resistance between the negative electrode base material and the negative electrode mixture layer. The structure of the intermediate layer is not particularly limited, and can be formed of, for example, a composition containing a resin binder and conductive particles. It should be noted that having “conductivity” means having a volume resistivity of 10 ⁷ Ω · cm or less measured according to JIS-H-0505 (1975), and “non-conductivity”. Means that the above volume resistivity is more than 10 ⁷ Ω · cm.

  The negative electrode mixture layer is a layer formed of a so-called negative electrode mixture material containing the negative electrode active material. The negative electrode mixture may contain an optional component such as a conductive agent, a binder, a thickener, and a filler, if necessary. The negative electrode mixture layer is formed by applying a slurry of the negative electrode mixture or the like.

  The lower limit of the content of the negative electrode active material in the negative electrode mixture layer (negative electrode mixture) is, for example, 50% by mass, and preferably 60% by mass. On the other hand, the upper limit of this 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 electricity storage device. Examples of such a conductive agent include natural or artificial graphite, carbon black such as furnace black, acetylene black, and Ketjen black, metal, conductive ceramics, and the like, and acetylene black is preferable. Examples of the shape of the conductive agent include powder and fibrous shapes.

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

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

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

<Non-aqueous 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 non-aqueous electrolyte secondary battery will be described as an example of the non-aqueous electrolyte storage element. The positive electrode and the negative electrode usually form an electrode body which 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 non-aqueous electrolyte. The non-aqueous electrolyte is interposed between the positive electrode and the negative electrode. Further, as the case, a known aluminum case, resin case or the like which is usually used as a case of a non-aqueous electrolyte secondary battery can be used.

(Positive electrode)
The positive electrode has a positive electrode base material and a positive electrode mixture layer arranged on the positive electrode base material directly or via an intermediate layer. The intermediate layer can have the same structure as the intermediate layer of the negative electrode.

  The positive electrode base material has conductivity. As the material of the base material, metals such as aluminum, copper, titanium, tantalum, and stainless steel or alloys thereof are used. Among these, aluminum and aluminum alloys are preferable from the viewpoint of balance between potential resistance, high conductivity, and cost. In addition, examples of the form of forming the positive electrode substrate include a foil and a vapor deposition film, and the foil is preferable from the viewpoint of cost. That is, aluminum foil is preferable as the positive electrode substrate.

  The positive electrode composite material layer is formed of a so-called positive electrode composite material containing a positive electrode active material. Further, the positive electrode mixture forming the positive electrode mixture layer contains optional components such as a conductive agent, a binder (binder), a thickener, and a filler, if necessary. As the optional components such as the conductive agent, the binder, the thickener, and the filler, those similar to the above-mentioned negative electrode mixture layer can be used.

As the positive electrode active material, a conventionally known positive electrode active material for a non-aqueous electrolyte storage element is used. As a specific positive electrode active material, for example, a composite oxide represented by Li _x MO _y (M represents at least one transition metal other than Mo) (Li _x having a layered α-NaFeO ₂ type crystal structure) _{CoO 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 or the like, having a spinel type crystal structure _{Li 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, X is For example, polyanion compounds represented by P, Si, B, V, etc. (LiFePO ₄ , LiMnPO ₄ , LiNiPO ₄ , LiCoPO ₄ , Li ₃ V ₂ (PO ₄ ) ₃ , Li ₂ MnSiO ₄ , Li ₂ CoP). O ₄ F and the like).

(Negative electrode)
The negative electrode according to the embodiment of the present invention is used as the negative electrode. The details of the negative electrode are as described above.

(Separator)
As the material of the separator, for example, woven cloth, non-woven cloth, 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 non-aqueous electrolyte. As the main component of the separator, polyolefin such as polyethylene or polypropylene is preferable from the viewpoint of strength, and polyimide or aramid is preferable from the viewpoint of resistance to oxidative decomposition. Further, these resins may be combined.

  An inorganic layer may be arranged between the separator and the electrode (usually the positive electrode). This inorganic layer is a porous layer also called a heat resistant layer or the like. A separator having an inorganic layer formed on 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.

(Non-aqueous electrolyte)
As the above-mentioned non-aqueous electrolyte, a known electrolyte usually used for non-aqueous electrolyte storage elements (secondary batteries) can be used. The non-aqueous electrolyte contains 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 a lithium salt, a sodium salt, a potassium salt, a magnesium salt, an onium salt and the like, and a 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 , and LiN (SO ₂ F) ₂ , LiSO ₃ CF ₃ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO. _{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 fluorinated hydrocarbon group, Examples thereof include 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 also be used.

  The non-aqueous electrolyte storage element can be manufactured by using the negative electrode according to the embodiment of the present invention. The manufacturing method is, for example, a step of manufacturing a positive electrode, a step of manufacturing a negative electrode, a step of preparing a non-aqueous electrolyte, a positive electrode and a negative electrode, the electrode body which is alternately superposed by laminating or winding via a separator. And a step of housing the positive electrode and the negative electrode (electrode body) in a case, and a step of injecting the nonaqueous electrolyte into the case. After the injection, the injection port is sealed to obtain the nonaqueous electrolyte storage element.

<Other embodiments>
The present invention is not limited to the above embodiment, and can be carried out in various modified and improved modes in addition to the above modes. For example, in the above negative electrode, the intermediate layer may not be provided, and the negative electrode mixture may not form a clear layer. For example, the negative electrode may have a structure in which a negative electrode mixture is carried on a mesh-shaped negative electrode base material. Further, in the above-mentioned embodiment, the non-aqueous electrolyte power storage element is mainly described as a secondary battery, but other non-aqueous electrolyte power storage elements may be used. Examples of other non-aqueous 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 that is an embodiment of the nonaqueous electrolyte storage element. It should be noted that the figure is a perspective view of the inside of the container. In the nonaqueous electrolyte storage element 1 shown in FIG. 1, the 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 with a separator interposed therebetween. 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 non-aqueous electrolyte storage element (secondary battery) is not particularly limited, and examples thereof include a cylindrical battery, a rectangular battery (rectangular battery), and a flat battery. The present invention can also be realized as a power storage device including a plurality of the above non-aqueous electrolyte power storage elements. An embodiment of the 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 electric vehicles (EV), hybrid vehicles (HEV), and plug-in hybrid vehicles (PHEV).

  Hereinafter, the present invention will be described more specifically with reference to Examples, but 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, Inc.), molybdenum trioxide (MoO ₃ ) (manufactured by Kojundo Chemical Co., Ltd.), and acetylene black as a reducing agent were used, and the molar ratio of Li: Mo: C was 4 :. It was weighed so as to be 4: 3. These were put into a zirconia pot having an inner volume of 80 mL containing 90 g (about 250 pieces) of zirconia balls having a diameter of 5 mm, and the lid was covered. This was set in a planetary ball mill ("pulverisette 5" manufactured by FRITSCH), mixed at a revolution speed of 120 rpm for 9 minutes, and then allowed to rest for 1 minute, which was repeated 6 times in total. Then, the operation of opening the lid, stirring the mixture in the pot with a spoon, mixing again for 9 minutes at the revolution speed of 120 rpm, and then putting a pause for 1 minute was repeated twice in total. Next, this mixed powder was placed in an alumina crucible (model number: 1-7745-07) having a volume of 30 mL, and this crucible was installed in a tabletop vacuum / gas displacement furnace (“KDF75” manufactured by Denken Hydental Co., Ltd.). . Then, the temperature was raised from room temperature to 1000 ° C. under normal pressure in a nitrogen stream at a constant heating rate over 10 hours, and the temperature was maintained for 4 hours and then naturally cooled 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, Inc.) were used in a Mo: P molar ratio of 90:10 (Example 1) and 80:20 (Example 1). Example 2), 70:30 (Example 3), and 60:40 (Example 4), and the total weight of these oxides was about 4.5 g each. . These were placed in a tungsten carbide pot having an internal volume of 80 mL containing 250 g (about 250) of tungsten carbide balls having a diameter of 5 mm, and the lid was capped in a glove box maintaining an argon atmosphere. This was set in a planetary ball mill (“pulverisette 5” manufactured by FRITSCH), mixed for 12 minutes at a revolution speed of 400 rpm, and then a pause for 3 minutes was repeated 16 times in total. In this way, 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) A 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, Inc.) were weighed so that the molar ratio of Mo: C 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 prepared.

[Comparative Example 2] (Synthesis of lithium molybdenum composite oxide)
The Mo: P molar ratio was set to 100: 0, and this was set in a planetary ball mill ("pulverisette 5" manufactured by FRITSCH), mixed for 12 minutes at a revolution speed of 400 rpm, and then allowed to 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 that the steps were repeated.

[Comparative Example 3]
Molybdenum trioxide (MoO ₃ ) (manufactured by Kojundo Chemical Co., Ltd.) was prepared.

[Comparative Example 4] (Synthesis of Li ₄ Mo ₅ O ₁₇ )
Molybdenum trioxide (MoO ₃ ) (manufactured by Kojundo Chemical Co., Ltd.) and lithium carbonate (Li ₂ CO ₃ ) (manufactured by Nacalai Tesque, Inc.) were weighed so that the molar ratio of Li: Mo was 4: 5. The composition was the same as in Synthesis Example 1, except that the temperature was raised from room temperature to 500 ° C. under normal pressure at a constant rate over 10 hours at a constant rate, and the temperature was kept at 500 ° C. for 52 hours. A lithium molybdenum composite oxide represented by the formula Li ₄ Mo ₅ O ₁₇ was prepared.

[Comparative Example 5] (Synthesis of Li ₂ MoO ₄ )
Molybdenum trioxide (MoO ₃ ) (manufactured by Kojundo Chemical Co., Ltd.) and lithium carbonate (Li ₂ CO ₃ ) (manufactured by Nacalai Tesque, Inc.) were weighed so that the molar ratio of Li: Mo was 2: 1. The composition was the same as in Synthesis Example 1 except that the temperature was raised from room temperature to 600 ° C. under normal pressure at a constant rate over 10 hours at a constant rate, and the temperature was kept at 600 ° C. for 4 hours. A lithium molybdenum composite oxide represented by the formula Li ₂ MoO ₄ was produced.

[Comparative Example 6] (lithium phosphate)
A treatment was performed in the same manner as in Example 1 except that the Mo: P molar ratio 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, Inc.) and germanium oxide (GeO ₂ ) (manufactured by Kojundo Chemical Co., Ltd.) were weighed out so that the molar ratio of Li: Ge was 2: 1. These were put into a zirconia pot having an inner volume of 80 mL containing 90 g (about 250 pieces) of zirconia balls having a diameter of 5 mm. 10 mL of ethanol was further added to this pot, and the pot was covered. This was set in a planetary ball mill ("pulverisette 5" manufactured by FRITSCH), mixed at a revolution speed of 300 rpm for 9 minutes, and then allowed to rest for 1 minute, which was repeated 6 times in total. This mixture was dried at 80 ° C. for 3 hours or more to obtain a mixed powder. This mixed powder was placed in an alumina crucible (model number: 1-7745-07) having a volume of 30 mL, and the crucible was installed in a tabletop vacuum / gas displacement furnace (“KDF75” manufactured by Denken Hydental Co., Ltd.). Then, the temperature was raised from room temperature to 950 ° C. in normal time in an air stream for 10 hours, and the temperature was maintained at this temperature for 4 hours, and then naturally cooled to room temperature. In this way, a lithium germanium composite oxide represented by the composition formula Li ₂ GeO ₃ was prepared.

[Comparative Example 7] (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 oxide 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. The thing was made.

[Analysis of complex oxides]
The composite oxides obtained in Examples 1 to 5 and Comparative Examples 1 to 7 were analyzed by the following method. Powder X-ray diffraction measurement was performed using an X-ray diffractometer (“MiniFlex II” manufactured by Rigaku). The radiation source was CuKα rays, the tube voltage was 30 kV, the tube current was 15 mA, and the diffracted X-rays were 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 scan 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 6 are shown in FIG. Moreover, the X-ray diffraction pattern of the composite oxides of Example 5 and Comparative Example 7 is shown in FIG. The obtained X-ray diffraction data was subjected to Rietveld analysis using the "RIETAN 2000" program.

  In the Rietveld analysis of the composite oxide of Example 1, the Pearson VII function was used as the function representing the profile, and the 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 measured value, and a graph showing the difference therebetween are shown in FIG. The crystal structure model shown in Table 1 sufficiently reduced the difference between the calculated value and the actually measured value as shown in FIG. Further, the reliability factors are Rwp = 4.73%, RI = 1.55%, and RF = 0.82%, respectively, which shows that the difference between the calculated value and the actually measured value is sufficiently small. From these results, it was assumed that the crystal structure model shown in Table 1 was appropriate.

In the Rietveld analysis of each of the composite oxides of Examples 2 and 3, the Pearson VII function was used as a function representing the profile, and α-NaFeO ₂ type crystal structure model (first phase) and NaCl as shown in Table 2 were used. The two-phase crystal structure model (second phase) coexisting model was used. As an example, Table 2 shows a refined crystal structure model as a result of Rietveld analysis of the lithium molybdenum phosphorous oxide of Example 2, and FIG. 6 shows a calculated value, an actually measured value, and a graph showing the difference therebetween. With 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%, respectively. Yes, it was shown that the difference between the calculated value and the measured value was sufficiently small. From these results, it was assumed that the crystal structure model shown in Table 2 was appropriate.

Further, the 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 for expressing the profile, and a model of only one phase of the α-NaFeO ₂ type crystal structure model as shown in Table 3 was used. The refined crystal structure model is shown in Table 3, and the calculated value, the measured value, and a graph showing the difference therebetween are shown in FIG. 7. The reliability factor was Rwp = 5.67%, which was worse than the above result Rwp = 4.84%. It is considered that this is due to poor fitting of the peaks near 38 ° and 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 a 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. 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, and α-NaFeO ₂ type crystal structure model (first phase) and NaCl type crystal as shown in Table 4 were used. 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, Table 4 shows a refined crystal structure model, and FIG. 8 shows a calculated value, an actually measured value, and a graph showing the difference therebetween. With 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%, first phase RI = 1.12%, RF = 0.61%, second phase RI = 1.05%, RF = 0.61%, respectively. Yes, it was shown that the difference between the calculated value and the measured value was sufficiently small. From these results, it was assumed that the crystal structure model shown in Table 4 was appropriate.

As a result of the analysis of the complex oxides of Examples and Comparative Examples other than the above-described Examples 1, 2 and 5, which are described in detail, the assignable space groups are as follows.
-Example 1 and comparative examples 2 and 7: 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 coexisting)
Comparative Example 1: Space group C2 / m or R-3m
Comparative Example 3: MoO ₃ (PDF No. 00-000-1672)
Comparative Example 4: Li ₄ Mo ₅ O ₁₇ (PDF No. 01-088-1122)
Comparative Example 5: Li ₂ MoO ₄ (PDF No. 00-012-0763)
Comparative Example _6: Li ₃ PO 4 (PDF number 00-025-1030)

  From the above analysis, it was found that in Examples 1 to 5 and Comparative Examples 2 and 7, the mechanochemical reaction proceeded in the course of the treatment by the planetary ball mill. On the other hand, in Comparative Example 6, the mechanochemical reaction did not proceed during the process of the planetary ball mill, and the particles were only crushed.

[Preparation of non-aqueous electrolyte storage element (test battery)]
Using each of the composite oxides obtained in Examples 1 to 4 and 6 and Comparative Examples 6 and 7 as a negative electrode active material, a negative electrode was 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 inner volume of 80 mL containing 90 g (about 250 pieces) of zirconia balls having a diameter of 5 mm. 10 mL of acetone was further added to this pot, and the pot was capped in a glove box maintaining an argon atmosphere. This was set on a planetary ball mill (“pulverisette 5” manufactured by FRITSCH), mixed for 12 minutes at an orbital rotation speed of 300 rpm, and then put into a pause for 3 minutes, which was repeated 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, a 12 mass% N-methylpyrrolidone (NMP) solution of PVDF, and NMP were placed in a predetermined plastic container, and the container was capped in a glove box maintaining an argon atmosphere. This was set in a stirring and defoaming device (“Awatori Kentaro” (trade name) manufactured by Shinky Co., Ltd.) and sufficiently kneaded at 2000 rpm to prepare a slurry containing N-methylpyrrolidone (NMP) as a dispersion medium. . The mass ratio of the negative electrode active material, AB and PVDF in the slurry is 65:20:15. This slurry was applied to one side of a copper foil substrate having a thickness of 20 μm. This was dried on a hot plate at 80 ° C. for 60 minutes to evaporate the dispersion medium, and then roll-pressed to obtain a negative electrode.

  Regarding Example 5, a negative electrode was obtained in the same manner as above, except that the operation of mixing for 9 minutes at the revolution speed of 300 rpm for 9 minutes and then putting a pause of 1 minute was repeated 6 times in total.

  Further, each composite oxide obtained in Comparative Examples 1 and 2 was used as a negative electrode active material to prepare a negative electrode 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 inner volume of 80 mL containing 90 g (about 250 pieces) of zirconia balls having a diameter of 5 mm. 10 mL of acetone was further added to this pot, and the pot was capped in a glove box maintaining an argon atmosphere. This was set in a planetary ball mill (“pulverisette 5” manufactured by FRITSCH), mixed for 12 minutes at a revolution speed of 240 rpm, and then a pause for 3 minutes was repeated a total of 48 times. This mixture was dried with a dryer at 75 ° C. for 3 hours or more to prepare a mixed powder. 1.6 g of this mixed powder, 0.1 g of AB, a 12 mass% N-methylpyrrolidone (NMP) solution of PVDF, and NMP were placed in a predetermined plastic container, and the container was capped in a glove box maintaining an argon atmosphere. This was set in a stirring and defoaming device (“Awatori Kentaro” (trade name) manufactured by Shinky Co., Ltd.) and sufficiently kneaded at 2000 rpm to prepare a slurry containing N-methylpyrrolidone (NMP) as a dispersion medium. . The mass ratio of active material, AB and PVDF in the slurry is 65:20:15. This slurry was applied to one side of a copper foil substrate having a thickness of 20 μm. This was dried on a hot plate at 80 ° C. for 60 minutes to evaporate the dispersion medium, and then roll-pressed to obtain a negative electrode.

  Further, each composite oxide obtained in Comparative Examples 3 to 5 was used as a negative electrode active material to prepare a negative electrode 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 inner volume of 80 mL containing 90 g (about 250 pieces) of zirconia balls having a diameter of 5 mm. 10 mL of acetone was further added to this pot, and the pot was capped in a glove box maintaining an argon atmosphere. This was set in a planetary ball mill ("pulverisette 5" manufactured by FRITSCH), mixed at a revolution speed of 100 rpm for 9 minutes, and then allowed to rest for 1 minute, which was repeated 6 times in total. This mixture was dried with a dryer at 75 ° C. for 3 hours or more to prepare a mixed powder. 2.55 g of this mixed powder, a 12 mass% N-methylpyrrolidone (NMP) solution of PVDF, and NMP were placed in a predetermined plastic container, and the container was capped in a glove box maintaining an argon atmosphere. This was set in a stirring and defoaming device (“Awatori Kentaro” (trade name) manufactured by Shinky Co., Ltd.) and sufficiently kneaded at 2000 rpm to prepare a slurry containing N-methylpyrrolidone (NMP) as a dispersion medium. . The mass ratio of the negative electrode active material, AB and PVDF in the slurry is 65:20:15. This slurry was applied to one side of a copper foil substrate having a thickness of 20 μm. This was dried on a hot plate at 80 ° C. for 60 minutes to evaporate the dispersion medium, and then roll-pressed to obtain a negative electrode.

A test battery was assembled using each of the above negative electrodes as a working electrode, and the behavior as a negative electrode was evaluated. For the purpose of accurately observing the independent behavior, a metal foil in which metallic lithium was in close contact with a nickel foil current collector was used. Here, a sufficient amount of metallic lithium was placed so that the capacity of the test battery was not limited by the counter electrode. As an electrolyte, a solution prepared by dissolving LiPF ₆ in a mixed solvent of ethylene carbonate (EC) / ethyl methyl carbonate (EMC) / dimethyl carbonate (DMC) at a volume ratio of 6: 7: 7 so that the concentration becomes 1 mol / L. Was used. As the separator, a polypropylene microporous membrane whose surface was modified with polyacrylate was used. A metal resin composite film composed 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. Stored. Then, the fusion-bonding margin in which the inner surfaces of the metal resin composite film faced each other was hermetically sealed except for the portion to be the liquid injection hole, and after pouring the electrolytic solution, the liquid injection hole was sealed.

[Charge / discharge test (0.2-3.0V)]
In the following tests, voltage control was performed between the working electrode and the counter electrode, but since the dissolution / precipitation reaction resistance of metallic lithium in the counter electrode is extremely low, the terminal voltage during charging / discharging was measured using metallic lithium. It can be regarded as equal to the potential of the working pole with respect to the pole. Further, in the following tests, the above composite oxide was used as a negative electrode active material used in the negative electrode of a non-aqueous electrolyte storage element that is assumed to start from charging in combination with a positive electrode containing lithium that can be electrochemically occluded and released. For the purpose of evaluation, the operation was started from the operation of energizing the composite oxide in the reducing direction, which is a reaction in which lithium ions are electrochemically occluded.

A charge / discharge cycle test was performed in a thermostatic chamber set at 25 ° C. using the non-aqueous electrolyte storage elements obtained by using the composite oxides of Examples 1 to 5 and Comparative Examples 1 to 5 and 7. The charging is constant current constant voltage (CCCV) charging, the charging lower limit potential is 0.2 V (vs. Li ^/ Li ⁺ ), and the charging end condition is when the charging current decays to 2 mA / g or the charging lower limit potential is reached. It was the time when 15 hours had passed since the start. The discharge was constant current (CC) discharge, and the discharge end potential was 3.0 V (vs. Li ^/ Li ⁺ ). The constant current value for charging and discharging was 50 mA / g with respect to the mass of the negative electrode active material contained in the negative electrode. The above charge and discharge were set as one cycle, and this cycle was performed 10 times. In each cycle, a rest time of 10 minutes was set after charging and discharging. Table 5 shows the discharge capacity at the second cycle in this charge / discharge cycle test. The discharge capacity shown here is a value obtained by removing the contribution of AB estimated in an AB battery described later from the discharge capacity per mass of the negative electrode active material excluding AB contained in the negative electrode. Further, the ratio of the discharge capacity at the 10th cycle to the discharge capacity at the 2nd cycle was determined as “capacity retention rate (%)”. This capacity retention rate is also shown in Table 5. Table 5 also shows the method of synthesizing each composite oxide. In the table, "MC method" indicates a mechanochemical method. Further, FIG. 9 shows the discharge curves of the second cycle, the seventh cycle, and the tenth cycle of Example 5.

The working electrode (negative electrode) according to the above-mentioned Examples and Comparative Examples contains acetylene black (AB). Therefore, since the observed charge / discharge behavior includes the contribution of AB, it is necessary to consider the contribution. Therefore, a test battery (hereinafter, referred to as “AB battery”) was manufactured by the same procedure as in Example 1 except that electrochemically inactive Al ₂ O ₃ was used instead of the lithium molybdenum composite oxide. A charge / discharge test was conducted under the same conditions. The discharge capacity per mass of Al ₂ O ₃ in the second cycle in the AB battery was 41 mAh / Al ₂ O ₃ -g.

[Charge / discharge test (0.1-3.0V)]
A charge / discharge test (0.1-3.0V) was performed in the same manner as the charge / discharge test (0.2-3.0V) except that the charge lower limit potential was 0.1V (vs. Li ^/ Li ⁺ ). ) Was done. Table 5 also shows the discharge capacity of the second cycle in this charge-discharge cycle test, and the capacity retention rate, which is the ratio of the discharge capacity of the 10th cycle to the discharge capacity of the second cycle. The discharge capacity shown here is a value obtained by removing the contribution of AB estimated in an AB battery described later from the discharge capacity per mass of the negative electrode active material excluding AB contained in the negative electrode. Further, FIG. 10 shows the discharge curves of the second cycle, the seventh cycle, and the tenth cycle of Example 2.

In order to consider the contribution of AB, an AB battery was prepared in the same manner as the above charge / discharge test (0.2-3.0V), and a charge / discharge test (0.1-3.0V) was performed. In the second cycle, the discharge capacity per mass of Al ₂ O ₃ was 56 mAh / Al ₂ O ₃ -g.

[Charge / Discharge Test: Comparative Example 6 (Li ₃ PO ₄ )]
Regarding the non-aqueous electrolyte electricity storage device obtained by using the composite oxide (Li ₃ PO ₄ ) of Comparative Example 6, the charge lower limit potential was set to 0.0 V (vs. Li / Li ⁺ ), and A charge / discharge test was performed in the same manner as the discharge test (0.2-3.0V). In this non-aqueous electrolyte storage element, the discharge capacity excluding the contribution of AB was 0 mAh / g.

  As shown in Table 5, the nonaqueous electrolyte storage elements of Examples 1 to 5 have a large discharge capacity of 400 mAh / g or more in a charge / discharge test (0.2-3.0 V) and a high discharge capacity of more than 95%. It can be seen that it has a capacity retention rate.

On the other hand, Comparative Example 1 using LiMoO ₂ obtained by firing has a small discharge capacity. Comparative Example 2 using LiMoO ₂ subjected to the MC method has a large discharge capacity but a low capacity retention rate. Comparative Examples 3 to 5 using MoO ₃ , Li ₄ Mo ₅ O ₁₇ or L ₂ MoO ₄ which are publicly known as the negative electrode active material also have large discharge capacities but low capacity retention rates. Further, in Comparative Example 6 using Li ₃ PO ₄ as the negative electrode active material, charging / discharging was substantially impossible.

  Further, Comparative Example 7 in which Ge is introduced into the lithium molybdenum oxide has a small discharge capacity and a low capacity retention rate. It is presumed that this is because Ge is redox-reduced during charge and discharge, resulting in deterioration. On the other hand, in Examples 1 to 5 in which elements such as P and C, which are difficult to be oxidized and reduced at the time of charging and discharging, and which have a high covalent bond with oxygen are introduced into the lithium molybdenum oxide, deterioration is less likely to occur at the time of charging and discharging It is estimated that the capacity maintenance rate is increasing.

  INDUSTRIAL APPLICABILITY The present invention can be applied to a non-aqueous electrolyte secondary battery used as a power source for a personal computer, an electronic device such as a communication terminal, an automobile, and the like, a negative electrode and a negative electrode active material provided therein.

1 Non-Aqueous Electrolyte Storage Element 2 Electrode Body 3 Container 4 Positive Electrode Terminal 4 ′ Positive Electrode Lead 5 Negative Terminal 5 ′ Negative Lead 20 Storage Unit 30 Storage Device

Claims (5)

A negative electrode active material for a non-aqueous electrolyte electricity storage device containing a composite oxide 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, Ga, As, Br, Te, I, or a combination thereof. 0 ≦ x, 0 <y < 1, 0 <z.)   The negative electrode active material according to claim 1, wherein the content of the element (A) with respect to the total content of the molybdenum and the element (A) is 1 mol% or more and less than 50 mol%. Negative electrode active material according to claim 1 or claim 2 comprising the composite oxide, the possible crystal structure belonging to the space group Fm-3m. A negative electrode for a non-aqueous electrolyte energy storage device having a negative electrode active material of any one of claims 1 to 3. A non-aqueous electrolyte storage element having the negative electrode according to claim 4 .

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