JP3013209B2 - Non-aqueous electrolyte secondary battery and method for producing negative electrode active material thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte secondary battery using a non-aqueous electrolyte having lithium ion conductivity as a negative electrode active material using a material capable of inserting and extracting lithium. The present invention relates to a novel negative electrode active material that provides a new secondary battery having a high energy density, excellent charge / discharge characteristics, and a long cycle life.

[0002]

2. Description of the Related Art Nonaqueous electrolyte batteries using lithium as a negative electrode active material have advantages such as high voltage, high energy density, low self-discharge, and excellent long-term reliability. It is already widely used as a power source for applications. However, with the recent remarkable development of portable electronic devices and communication devices,
To a battery as a power source it appeared equipment that requires a large current output as a large multi, from the viewpoint of size and weight of the economy and equipment, recharge and discharge possible, and the secondary battery is strong demand for high energy density Have been. For this reason, research and development to promote the non-aqueous electrolyte battery having a high energy density into a secondary battery has been actively carried out, and some of them have been put to practical use. However, energy density, charge / discharge cycle life, reliability, etc. are still insufficient. It is enough.

Conventionally, the following three types have been found as positive electrode active materials for use in the positive electrode of this type of secondary battery, depending on the form of charge / discharge reaction. The first type is
Metal chalcogenides such as TiS ₂ , MoS ₂ , NbSe ₃ , MnO ₂ , MoO ₃ , V ₂ O ₅ , Li _x Co
As in the case of metal oxides such as O ₂ , Li _x NiO ₂ , and Li _x Mn ₂ O _4, only lithium ions (cations) are intercalated or deintercalated between crystal layers or between lattice positions or lattice gaps. A type that comes in and out by reaction. The second type is a type such as a conductive polymer such as polyaniline, polypyrrole, polyparaphenylene, etc., in which only anions mainly enter and exit by stable doping and undoping reactions. The third type is such as a graphite intercalation compound, a conductive polymer such as polyacene, and the like.
It is a type (intercalation, deintercalation or doping, undoping, etc.) in which both lithium cation and anion can enter and exit.

On the other hand, as the negative electrode active material used for the negative electrode of this type of battery, when metallic lithium is used alone, the electrode potential is the lowest, so that it is combined with the positive electrode using the above-mentioned positive electrode active material. Although the output voltage of the battery is the highest and the energy density is high, it is preferable. However, dendrites and passive compounds are generated on the negative electrode during charging and discharging, and there is a problem that the deterioration due to charging and discharging is large and the cycle life is short. To solve this problem, (1) lithium and Al, Zn, Sn, Pb, Bi, Cd
Alloys with other metals such as (2) WO ₂ , MoO ₂ , Fe ₂
Inorganic compounds such as O ₃ and TiS ₂ , graphite, carbonaceous materials obtained by baking organic materials, etc., intercalation compounds or insertion compounds in which lithium ions are occluded in a skeleton structure, (3) lithium-doped polyacene, It has been proposed to use a substance capable of inserting and extracting lithium ions, such as a conductive polymer such as polyacetylene.

[0005]

However, in general,
In addition, as the negative electrode active material other than metallic lithium as described above
A negative electrode using a substance capable of inserting and extracting lithium ions,
Battery combining positive electrode using positive electrode active material as described above
When these are configured, the electrode potential of these negative electrode active materials becomes
Battery operation because it is more noble than the electrode potential of metallic lithium
When the voltage is used by using metallic lithium alone as the negative electrode active material,
There is a disadvantage that it is considerably lower than the case. For example, Lichi
And alloys of Al, Zn, Pb, Sn, Bi, Cd, etc.
0.2-0.8V if used, carbon-lithium interlayer
For compounds, 0-1 V, MoO_TwoAnd WO _TwoSuch as lithium ion
0.5-1.5 V operating voltage decreases with on-insertion compounds
You.

In addition, since elements other than lithium also serve as negative electrode components, the capacity and energy density per volume and weight are significantly reduced. Further, when the alloy of lithium and another metal of the above (1) is used, the efficiency of use of lithium during charge and discharge is low, and cracks occur in the electrodes due to repetition of charge and discharge, causing cracks and the like. Therefore, there is a problem that the cycle life is short, and in the case of the lithium intercalation compound or the insertion compound of (2), deterioration such as collapse of the crystal structure or generation of an irreversible substance due to overcharging and discharging occurs, and the electrode potential is high ( There is a drawback that the output voltage of a battery using this is low because there are many precious materials, and in the case of the conductive polymer of (3), the charge / discharge capacity, particularly, the charge / discharge capacity per volume is small. There's a problem.

Among the above-mentioned negative electrode active materials, tungsten dioxide WO ₂ having a rutile type crystal structure has the formula (1) WO ₂ + xLi ⁺ + xe ⁻ ⇔Li _{x with} respect to a positive electrode active material capable of inserting and extracting lithium. the cell reaction shown in WO ₂ (1), the electrode potential has a relatively lower potential of 0.5~1.0V to metallic lithium, and, 1 eq per WO ₂ by charging and discharging 1 An equivalent amount of lithium ion (corresponding to x = 1) can be intercalated and deintercalated, and a theoretical capacity density of 1500 mAh / cm ³ or more is expected. Particularly, as a negative electrode active material of this type of secondary battery, It is a promising substance.

However, even in the case of the lithium ion insertion compound WO ₂ , a phase transition occurs due to a phase change when 0.5 or more equivalents of lithium ions are intercalated per equivalent of WO ₂ . There is a problem that the rechargeable charge / discharge range is reversible at a typical charge / discharge voltage and current density, that is, the effective charge / discharge capacity is small, 50% or less of the above theoretical capacity, and the larger the current is, the smaller the capacity becomes.
In addition, there is a problem that when overdischarge is performed at 50% or more of the theoretical capacity, the charge / discharge capacity is significantly reduced. Further, there is a problem that since the change in the operating voltage due to the polarization at the time of discharge is large, the output voltage of a battery using the same greatly decreases. Note that cell using the WO ₂ is, JJAuborn and Y.
L. Barberio, J. Electrochem. Soc., 134, 638 ('87); DWMur
phy, FJDi Salvo, JNCarides, and JVWaszczak, Mate
r. Res. Bull., 13, 1395 ('78).

For this reason, at a high voltage and a high energy density,
In addition, in order to obtain a secondary battery having excellent charge / discharge characteristics and a long cycle life, the electrode potential with respect to lithium is low (low), and the collapse of the crystal structure and the generation of irreversible substances due to insertion and extraction of lithium ions during charge / discharge. It is necessary to use a negative electrode active material which does not deteriorate and has a large amount capable of reversibly inserting and extracting lithium ions, that is, a large effective charge / discharge capacity.

[0010]

In order to solve the above-mentioned problems, the present invention provides a negative electrode active material for this type of battery.
Te, intended to raise the use of products obtained by heat-treating a mixture of a lithium compound or lithium to produce an oxide of lithium by oxides or heating of the tungsten dioxide WO ₂ and lithium in a non-oxidizing atmosphere is there.

The negative electrode active material of the battery of the present invention can be produced as follows. As a lithium compound used as a raw material, the compound alone in an inert atmosphere,
Any material may be used as long as it generates lithium oxide by heating in a non-oxidizing atmosphere such as a reduced pressure atmosphere or a vacuum. For example, lithium oxide Li ₂ O, lithium LiOH or a hydrate thereof hydroxide, salts such as lithium carbonate Li ₂ CO ₃ or lithium nitrate LiNO _3, and organic compounds like lithium like.

Such a lithium oxide or a lithium compound which forms a lithium oxide by heating and a mixture of lithium and tungsten dioxide WO ₂ are mixed with an inert gas such as argon, neon, helium, krypton, xenon or nitrogen. Tungsten dioxide WO ₂ is not oxidized by heating to produce tungsten trioxide WO ₃ , such as in an atmosphere, in a vacuum, in a reduced pressure atmosphere, or in an atmosphere of a weak reducing gas such as carbon dioxide CO ₂ or a dilute hydrogen-containing gas. Heat treatment in a non-oxidizing atmosphere. The heat treatment temperature varies depending on the starting material and the heat treatment atmosphere, but is a temperature of 200 ° C. or higher, preferably 300 ° C. or higher, more preferably 50 ° C. or higher.
A temperature of 0 to 800 ° C is good. At temperatures below 200 ° C,
The solid solution reaction between lithium and oxygen in the lithium compound and tungsten dioxide WO ₂ is insufficient, and at a temperature of 800 ° C. or more, there is a loss due to sublimation of tungsten dioxide WO ₂ and the composition of the product changes, Temperatures in this range are preferred.

[0013] Lithium Such oxides or lithium compound or lithium and products obtained by heat treatment of a mixture of tungsten dioxide WO ₂ of lithium in the crystal structure of the tungsten dioxide WO ₂ As shown in Examples described later And a composite oxide Li _x WO _{2 + y} of lithium and tungsten in which oxygen and oxygen are dissolved. However, the amount of lithium x and the amount of oxygen y are 0 <x and 0 ≦ y depending on the selection of the starting materials, their mixing ratio, and the atmosphere and temperature of the heat treatment.
≦ 0.5x + 0.5 is possible. That is, the value of y can be a non-stoichiometric composition in which oxygen is excessive or insufficient up to about 25% of a stoichiometric composition.

The heat-treated product of the mixture of tungsten dioxide WO ₂ and the oxide of lithium or the lithium compound or lithium obtained as described above is subjected to processing such as pulverization and sizing or granulation as needed. Can be used as a negative electrode active material, or the heat-treated product can further occlude lithium ions by an electrochemical reaction of the heat-treated product with lithium or a lithium-containing material, or vice versa. A material in which the amount x of lithium is increased or decreased by releasing lithium ions from the heat-treated product may be used as the negative electrode active material.

Occlusion and release of lithium ions by electrochemical reaction to the heat-treated product can be performed in the battery after the battery is assembled or in or outside the battery during the battery manufacturing process. Can be performed as follows. That is, (1) the heat treatment product or a mixture of the heat treatment product and a conductive agent and a binder formed into a predetermined shape is used as one electrode (working electrode) and contains metallic lithium or lithium. The other electrode (counter electrode) is used as the other electrode (counter electrode) to make contact with the lithium-ion conductive non-aqueous electrolyte so that both electrodes face each other to form an electrolytic cell. Then, lithium ions are electrochemically occluded in the heat-treated product. A non-aqueous electrolyte secondary battery is formed by using the obtained working electrode as it is as a negative electrode or as a negative electrode active material constituting the negative electrode.

(2) The heat-treated product or a mixture of the heat-treated product with a conductive agent and a binder is formed into a predetermined shape, and lithium or an alloy of lithium or the like is pressed or brought into contact therewith. The negative electrode is incorporated into a non-aqueous electrolyte secondary battery as a negative electrode. A method in which the laminated electrode self-discharges by touching the electrolyte in the battery and electrochemically occludes lithium in the heat-treated product.

(3) The heat-treated product is used as a negative electrode active material,
A nonaqueous electrolyte secondary battery using a material containing lithium and capable of inserting and extracting lithium ions as a positive electrode active material is provided. A method in which lithium ions released from a positive electrode by being charged when used as a battery are occluded in the heat-treated product. In the case where lithium is released from the heat-treated product, the current flowing in the method (1) or (3) may be applied in the opposite direction.

The tungsten dioxide thus obtained is
WO_TwoAnd lithium oxide or lithium
Mixing with lithium compound or lithium to form oxide
Heat-treated product or electrochemical treatment of the heat-treated product
If lithium is further absorbed or released by the reaction,
Used as a pole active material. On the other hand, as the positive electrode active material,
Like TiS_Two, MoS_Two, NbSe_ThreeEtc. metal cal
Cogenide, MnO_Two, MoO_Three, V_TwoO_Five, Li_x
CoO_Two, Li _xNiO_Two, Li_xMn_TwoO_FourEtc. metal
Oxides, polyaniline, polypyrrole, polyparaphenylene
Conductive polymers such as lenpolyacene, and graphite layers
Absorbs lithium ions and / or anions
Various substances that can be stored and released can be used. In particular,
An oxide or lithium compound of lithium according to the present invention or
Lithium and tungsten dioxide WO_TwoHeat treatment of the mixture with
A negative electrode using a treatment product as a negative electrode active material is compatible with metallic lithium.
Of low electrode potential (low) and low voltage of 2V or less
Because it has the advantage that the discharge capacity is extremely large,
Electrode voltage for metallic lithium such as the above-mentioned metal oxide
3 V or more, more preferably V_TwoO_Five, MnO_Two, L
i_xCoO_Two, Li_xNiO_TwoAnd Li_xMn_TwoO_FourAnd so on
Has a high potential of 3.5V or 4V or more like
By combining with a positive electrode using (noble) active material
Secondary with high voltage, high energy density and excellent charge / discharge characteristics
It is particularly preferable because a battery can be obtained.

As the electrolyte, γ-butyrolactone, propylene carbonate, ethylene carbonate,
LiClO ₄ , LiPF ₆ , LiBF as a supporting electrolyte in a single or mixed solvent of organic solvents such as butylene carbonate, dimethyl carbonate, diethyl carbonate, methylformate, 1,2-dimethoxyethane, tetrahydrofuran, dioxolan, and dimethylformamide
₄ , an organic electrolyte solution in which a lithium ion dissociable salt such as LiCF ₃ SO ₃ is dissolved, a polymer solid electrolyte in which the lithium salt is dissolved in a polymer such as polyethylene oxide or a crosslinked polyphosphazene, or Li ₃ N; Any non-aqueous electrolyte having lithium ion conductivity such as an inorganic solid electrolyte such as LiI may be used.

[0020]

Negative electrode and the negative electrode active material to a heat treatment product of a mixture of lithium compound or lithium to produce an oxide of lithium by oxides or heating of the tungsten dioxide WO ₂ and lithium according to the action of the present invention is to provide a non-aqueous electrolyte At least 0 to 3 with respect to the lithium reference electrode (metal lithium)
Lithium ions can be stably and repeatedly absorbed and released in the range of the electrode potential of V, and can be used as a negative electrode of a secondary battery that can be repeatedly charged and discharged by such an electrode reaction. In particular, 0 for the lithium reference electrode (metal lithium).
It has a high-capacity charge / discharge region that can stably store and release lithium ions and repeatedly charge and discharge in a base potential region of up to 2 V. In addition, compared with tungsten dioxide WO ₂ or molybdenum dioxide MO ₂ which has been conventionally used as a negative electrode active material of this type of battery, the amount capable of inserting and extracting lithium ions reversibly, that is, the effective charge / discharge capacity is extremely large, and the charge / discharge capacity is large. Because of the small polarization, it is possible to charge and discharge with a large current, and furthermore, almost no deterioration such as generation of irreversible substances due to overcharging and overdischarging is observed, and it is possible to obtain an extremely stable secondary battery with a long cycle life. it can.

The reason why such excellent charge / discharge characteristics are obtained is not necessarily clear, but is presumed as follows. That is, the heat treatment product of a mixture of lithium compound or lithium to produce an oxide of lithium by oxides or heating of the tungsten dioxide WO ₂ and the lithium is a novel negative active material according to the present invention, tungsten dioxide W
Lithium and oxygen are dissolved in the skeleton structure of O ₂ , and a three-dimensional structure similar to WO ₂ containing lithium ions is formed in the crystal structure in advance, and the mobility of lithium ions in this structure is low. This is presumed to be due to the high number of sites that can store and store lithium ions, which facilitates the storage and release of lithium ions, and hardly causes a phase change.

Hereinafter, the present invention will be described in more detail with reference to examples.

[0023]

【Example】

(Example 1) FIG. 1 is a sectional view of a coin-type battery showing an example of a test cell used for evaluating the performance of a negative electrode active material of a nonaqueous electrolyte secondary battery according to the present invention. In the figure, reference numeral 1 denotes a counter electrode case also serving as a counter electrode terminal, which is formed by drawing a stainless steel plate having one outer surface Ni-plated. 2
Is a counter electrode current collector made of a stainless steel net, which is spot-welded to the counter electrode case 1. The counter electrode 3 is obtained by punching an aluminum plate having a predetermined thickness to a diameter of 15 mm, fixing the aluminum plate to the counter electrode current collector 2, and punching a lithium foil having a predetermined thickness to a diameter of 14 mm. Reference numeral 7 denotes a working electrode case made of stainless steel with one outer surface Ni-plated, and also serves as a working electrode terminal.

Reference numeral 5 denotes a working electrode formed by using a negative electrode active material according to the present invention to be described later or a comparative active material according to a conventional method. The working electrode 5 is press-formed integrally with a working electrode current collector 6 made of a stainless steel net. Have been. Reference numeral 4 denotes a separator made of a porous film of polypropylene, which is impregnated with an electrolytic solution. 8 is a gasket mainly composed of polypropylene, interposed between the counter electrode case 1 and the working electrode case 7,
While maintaining the electrical insulation between the counter electrode and the working electrode, the opening of the working electrode case is bent inward and caulked to seal and seal the battery contents. The electrolyte is a mixed solvent of propylene carbonate and 1,2-dimethoxyethane in a volume ratio of 1: 1 and lithium perchlorate LiClO.
₄ dissolved at 1 mol / l was used. The size of the battery was 20 mm in outer diameter and 1.6 mm in thickness.

The working electrode 5 was manufactured as follows. Lithium hydroxide LiOH.H ₂ O and commercially available tungsten dioxide WO ₂ having a purity of 99.9% are sufficiently mixed in a molar ratio of Li: W = 1: 1 using a mortar, and the mixture is placed in a stream of nitrogen gas. Heat treated at a temperature of 700 ° C. for 12 hours, and after cooling,
It was pulverized and sized to a particle size of 53 μm or less. The product thus obtained is used as an active material a according to the present invention, and graphite is mixed with a conductive agent and a crosslinked acrylic resin as a binder in a weight ratio of 30: 65: 5. a working electrode mixture, then was pressed into pellets of the action electrode mixture diameter 15mm thickness 0.5mm at 2 ton / cm ² with the working electrode collector 6 made of a net made of stainless steel, 200 What was dried by heating under reduced pressure at 10 ° C. for 10 hours was used as a working electrode.

For comparison, the commercially available tungsten dioxide WO described above was used instead of the active material a according to the present invention.
_The same electrode as in the working electrode of the present invention described above, except that 2 was used as the active material as it was, and the same graphite as that used for the conductive agent was used as the active material for the working electrode. (Comparative working electrode) was prepared. The battery manufactured in this manner was aged at room temperature for one week, and then subjected to a charge / discharge test described later. Due to this aging, the lithium-aluminum laminated electrode of the counter electrode is sufficiently alloyed by contacting the non-aqueous electrolyte in the battery, and substantially all of the lithium foil is made of Li-A
Since the alloy was an 1 alloy, the battery voltage was stabilized at a value reduced by about 0.4 V as compared with a case where metallic lithium was used alone as a counter electrode.

The batteries manufactured in this manner are hereinafter abbreviated as batteries A, D, and E, respectively, corresponding to the active materials a, d, and e of the working electrodes used. 2 and 3 show X-ray diffraction patterns of the comparative active material d according to the conventional method and the active material a according to the present invention prepared as described above, using CuKα radiation. As is clear from FIG. 2, the diffraction pattern of the comparative active material d is JCPDS card No. 50
In good agreement with tungsten dioxide WO ₂ having a rutile structure described in 431. On the other hand, the diffraction pattern of the active material a according to the present invention has a diffraction peak similar to the diffraction pattern of the comparative active material d, but many new diffraction peaks appear, and lithium in the crystal structure of the tungsten dioxide WO ₂ appears. And oxygen form a solid solution to form a new composite oxide of lithium and tungsten.

These batteries A, D, and E were charged at a constant current of 0.4 mA (the direction of current in which the lithium ions were absorbed from the electrolyte to the working electrode in the direction of the battery reaction).
0.4 V, end voltage of discharge (current direction in which a battery reacts to release lithium ions from the working electrode into the electrolyte)
FIG. 5 shows the discharge characteristics in the third cycle when the charge / discharge cycle was performed under the condition of 5 V, and FIG. 6 shows the charge characteristics. The charge / discharge cycle started from charging. As is clear from FIGS. 5 and 6, the battery A according to the present invention has a remarkably large charge / discharge capacity and a reversible charge / discharge region significantly expanded as compared with the comparative batteries D and E. Also, the difference between the operating voltage of charging and discharging over the entire charge / discharge area is extremely small, and the polarization (internal resistance) of the battery is extremely small.
It can be seen that large current charging and discharging is easy.

Further, the decrease in discharge capacity (cycle deterioration) due to repeated charging and discharging is extremely small. That is, lithium ions are released into the electrolyte from the counter electrode Li-Al alloy by charging, and the lithium ions move in the electrolyte to react with the active material a of the present invention composed of the composite oxide of lithium and tungsten according to the present invention. Then, lithium ions are electrochemically occluded in the active material a. Next, upon discharging, lithium ions are released from the composite oxide into the electrolyte,
By moving in the electrolyte and being occluded in the counter electrode Li-Al alloy, it can be stably repeatedly charged and discharged. (Example 2) This example is a case where the comparison performed mixing of the lithium compound and tungsten dioxide WO ₂ as a raw material upon synthesis of the negative electrode active material at various composition ratios. Working electrode 5
Except for the active material, the same battery was produced in the same manner as in Example 1.

The active material used in the working electrode of this embodiment was manufactured as follows. Lithium hydroxide LiOH · H ₂ O commercial purity 99.9% and a tungsten dioxide WO ₂ Li: After W is weighed to make a predetermined molar ratio and thoroughly mixed in a mortar, and the mixture 70 in nitrogen gas stream
Heat treated at a temperature of 0 ° C. for 12 hours, and after cooling, a particle size of 53 μm
The powder was crushed and sized. However, the flow rate of the nitrogen gas during the heat treatment was set to be three times that of the first embodiment. The product thus obtained was used as the active material according to the invention. In this embodiment, the molar ratio of Li: W is (b1) 0.25: 1,
2) 0.5: 1, (b3) 1: 1, (b4) 2: 1 4
Various types were produced. For comparison, the same active material d and active material e as those used in Example 1 were used as active materials according to the conventional method not containing lithium in advance.

The batteries prepared in this manner were used as active materials b1, b2, b3, b4, d
And e, and are abbreviated as batteries B1, B2, B3, B4, D and E. FIG. 4 shows an X-ray diffraction diagram using CuKα radiation of the active material b3 of this example manufactured as described above. As is clear from the figure, the diffraction pattern of the active material b3 of this example is very similar to the diffraction pattern of the active material a according to the present invention of Example 1 (FIG. 3), and the relative intensity of each diffraction peak is high. There is no clear difference except for the differences. That is,
The active material b3 is presumed to be a composite oxide of lithium and tungsten that has a microstructure different from that of the active material a but has substantially the same basic structure.

The batteries B1, B2,
For B3, B4, D and E, the same charge / discharge cycle test as in Example 1 was performed. FIG. 7 shows the discharge capacity (cycle characteristics) of each cycle at this time. As is clear from FIG. 7, the batteries B1, B2, B3 and B4 according to the invention
Has a significantly larger discharge capacity than the comparative batteries D and E,
It can be seen that the reversible region of charge and discharge is significantly expanded. or,
The decrease in discharge capacity (cycle deterioration) due to repeated charge and discharge is extremely small. Furthermore, the batteries B1 to B4 of this embodiment
In the same manner as in the battery A according to the present invention of Example 1, the difference between the operating voltages for charging and discharging over the entire charge / discharge region is extremely small, the polarization (internal resistance) of the battery is extremely small, and the large current Easy charging / discharging results were obtained.

The reason for having such excellent charge / discharge characteristics is not necessarily clear, but is presumed as follows. That is, as described above, in the heat-treated product of the mixture of the tungsten compound and the lithium compound which are the active materials of the working electrodes of the batteries B1 to B4 according to the present invention, lithium and oxygen are previously dissolved in the crystal structure of the tungsten dioxide. And
Since a composite oxide of lithium and tungsten is formed and the crystal structure is changed, the mobility of lithium ions in this structure is high, and the structural change due to insertion and extraction of lithium ions is small and stable. This is presumed to be due to the easy insertion and extraction of lithium ions.

As is clear from FIG. 7, the lithium content x (the number of moles of lithium per mole of tungsten) at the time of synthesis by heat treatment of the active material of the present invention is x>
If it is 0, it has the effect as described above, but preferably x
This range is particularly preferable because the charge / discharge capacity is particularly large when ≧ 0.25, more preferably x ≧ 0.5. Furthermore, in the examples, only the case of a lithium-aluminum alloy was shown as a counter electrode, but the present invention is not limited to the examples, and as described above, TiS ₂ , MoS ₂ , NbSe
Metal chalcogenides such as ₃ , MnO ₂ , MoO ₃ , V ₂
O ₅ , Li _x CoO ₂ , Li _x NiO ₂ , Li _x Mn ₂
A positive electrode having a material capable of storing and releasing lithium cations and / or anions, such as a metal oxide such as O ₄ , a conductive polymer such as polyaniline, polypyrrole, polyparaphenylene, and polyacene, and a graphite intercalation compound, as an active material. It goes without saying that the counter electrode can be used in combination with the negative electrode using the negative electrode active material according to the present invention.

[0035]

As described above in detail, the present invention is, as the negative electrode active material of a nonaqueous electrolyte secondary battery, a lithium compound to form oxides of lithium by oxides or heating of the tungsten dioxide WO ₂ and lithium or A novel active material comprising a product obtained by heat-treating a mixture with lithium in a non-oxidizing atmosphere, wherein the negative electrode active material has a base voltage of 0 to 2 V with respect to a lithium reference electrode (metal lithium). Charge / discharge capacity is remarkably large, and the charge / discharge capacity is remarkably large, and the charge / discharge characteristics at high voltage / high energy density and large current in a wide potential region. , A secondary battery having excellent characteristics can be obtained. In addition, deterioration such as a decrease in discharge capacity due to repeated charge and discharge is hardly observed, and an extremely stable secondary battery having a long cycle life can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example of the structure of a battery implemented in the present invention.

FIG. 2 is a powder X-ray diffraction diagram of a comparative active material d according to a conventional method.

FIG. 3 is a powder X-ray diffraction diagram of an active material a according to the present invention.

FIG. 4 is an X-ray powder diffraction diagram of an active material b3 according to the present invention.

FIG. 5 is an explanatory diagram showing a comparison of discharge characteristics at the third cycle between a battery according to the present invention and a conventional battery.

FIG. 6 is an explanatory diagram showing a comparison of charging characteristics at the third cycle between a battery according to the present invention and a conventional battery.

FIG. 7 is an explanatory diagram showing a comparison of cycle characteristics between a battery according to the present invention and a conventional battery.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Counter electrode case 2 Counter electrode current collector 3 Counter electrode 4 Separator 5 Working electrode 6 Working electrode current collector 7 Working electrode case 8 Gasket

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-264370 (JP, A) JP-A-55-37797 (JP, A) JP-A-50-16036 (JP, A) (58) Investigation Field (Int.Cl. ⁷ , DB name) H01M 4/02-4/04 H01M 4/58 H01M 10/40

Claims (5)

(57) [Claims] 1. A positive electrode, a negative electrode, and lithium ion conductive material.
In a non-aqueous electrolyte secondary battery composed of a non-aqueous electrolyte, the negative electrode active material is a mixture of lithium hydroxide and tungsten dioxide.
The mixture was heated at a temperature in the range of 500 ° C to 800 ° C and ground.
A non-aqueous electrolyte secondary battery, which is a composite oxide. 2. The method according to claim 1, wherein the lithium hydroxide is LiOH.H _Two O
The non-aqueous electrolyte secondary battery according to claim 1, wherein 3. The method according to claim 1, wherein the composite oxide is a CuKα ray of 19.9.
X-ray diffraction at °, 21.1 °, 30.6 ° and 33.0 °
The non-aqueous electrolyte secondary battery according to claim 1, which has a peak. 4. The method according to claim 1, wherein said lithium hydroxide is replaced with a lithium oxide.
Selected from hydrates of lithium and lithium oxide and lithium nitrate
The non-aqueous electrolysis according to claim 1, wherein a lithium compound is mixed.
Quality rechargeable battery. 5. A composite of a positive electrode, lithium and tungsten
A negative electrode having an oxide negative electrode active material;
Non-aqueous electrolyte secondary battery composed of electrically conductive non-aqueous electrolyte
hand, The composite oxide is 19.9 ° and 21.1 ° by CuKα radiation.
And X-ray diffraction peaks at 30.6 ° and 33.0 °
Non-aqueous electrolyte secondary battery.