JP2009134970A - Nonaqueous electrolytic battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous electrolytic battery which obtains sufficient cycle characteristics even when a positive electrode material having an olivine structure is used. <P>SOLUTION: A negative electrode mixture layer 22B includes a carbon material having a specific surface area of 0.5 m<SP>2</SP>/g to 2 m<SP>2</SP>/g, and a high molecular compound serving as a binder that has a constitutional repeating unit derived from a vinylidene fluoride having a weight-average molecular weight of 250,000 to 350,000. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a non-aqueous electrolyte battery. More specifically, the present invention relates to a non-aqueous electrolyte battery including a lithium phosphate compound having an olivine structure in a positive electrode.

  In recent years, many portable electronic devices such as a camera-type VTR (Video Tape Recorder), a mobile phone, and a laptop computer have appeared, and their size and weight have been reduced. As portable power sources for these electronic devices, research and development for improving the energy density of batteries, particularly secondary batteries, are being actively promoted.

  Batteries using non-aqueous electrolytes, especially lithium ion secondary batteries, are expected to have higher energy density than lead batteries and nickel cadmium batteries, which are conventional aqueous electrolyte secondary batteries. The market is growing and the market is growing significantly.

  In particular, since the characteristics of lithium ion secondary batteries such as light weight and high energy density are suitable for use in electric vehicles and hybrid electric vehicles, studies aiming to increase the size and output of the batteries have become active.

In a nonaqueous secondary battery represented by a lithium ion secondary battery, an oxide positive electrode such as LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ is generally used as a positive electrode active material. This is because a high capacity, a high voltage can be obtained, and a high filling property can be obtained, which is advantageous for reducing the size and weight of portable devices.

  However, these positive electrodes start releasing oxygen at 200 ° C. to 300 ° C. when heated in a charged state. When oxygen release starts, a flammable organic electrolytic solution is used as the electrolytic solution. Therefore, when an oxide positive electrode is used, it is not easy to ensure safety particularly in a large battery.

  In contrast, A. K. It has been shown that the positive electrode material having an olivine structure reported by Padhi et al. Does not release oxygen even when the temperature exceeds 350 ° C. and is extremely excellent in safety. (See Non-Patent Document 1)

J. et al. Electrochem. Soc. , Vol. 144, p. 1188

In the positive electrode material having this olivine structure, charge / discharge proceeds in a two-layer coexistence state of LiFePO ₄ and FePO ₄ , so that the potential flatness is very high. For this reason, when performing constant current / constant voltage charging, which is a charging method of a normal lithium ion battery, there is a feature that charging is performed almost in a constant current charging state. Therefore, in a battery using a positive electrode material having an olivine structure, charging time can be shortened when charged at the same charge rate as compared with conventional positive electrode materials such as LiCoO ₂ , LiNiO ₂ , and LiMn ₂ O ₄ .

  However, in a battery using a positive electrode material having an olivine structure, since charging at a high current value continues for a relatively long time, the movement of Li ions in the negative electrode does not follow, and Li at the interface between the negative electrode and the electrolyte solution The ion concentration increases, and Li metal tends to be deposited on the negative electrode. As a result, in a battery using a positive electrode material having an olivine structure, sufficient cycle characteristics could not be obtained.

  Therefore, an object of the present invention is to provide a nonaqueous electrolyte battery that can obtain sufficient cycle characteristics even when a positive electrode material having an olivine structure is used.

In order to solve the above-mentioned problems,
The present invention includes a positive electrode including a lithium phosphate compound having an olivine structure, a negative electrode including a carbon material capable of doping and dedoping lithium and a binder, and a non-aqueous electrolyte.
The specific surface area of the carbon material is a 0.5m ² / g~2m ² / g,
The binder comprises a polymer compound having a repeating unit derived from vinylidene fluoride having a weight average molecular weight of 250,000 to 350,000.

In this invention, a repeating unit derived from vinylidene fluoride having a weight average molecular weight of 250,000 to 350,000 as a binder and a carbon material having a specific surface area of 0.5 m ² / g to ² m ² / g on the negative electrode. Therefore, sufficient cycle characteristics can be obtained even when a lithium phosphate compound having an olivine structure is used for the positive electrode.

  According to the present invention, sufficient cycle characteristics can be obtained even when a positive electrode material having an olivine structure is used.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a cross-sectional structure of a nonaqueous electrolyte battery according to an embodiment of the present invention. This battery is, for example, a non-aqueous electrolyte secondary battery, for example, a lithium ion secondary battery.

  As shown in FIG. 1, this secondary battery is a so-called cylindrical type, and a strip-shaped positive electrode 21 and a strip-shaped negative electrode 22 are interposed in a substantially hollow cylindrical battery can 11 via a separator 23. The wound electrode body 20 is wound. The battery can 11 is made of, for example, iron (Fe) plated with nickel (Ni), and has one end closed and the other end open. Inside the battery can 11, a pair of insulating plates 12 and 13 are arranged perpendicular to the winding peripheral surface so as to sandwich the winding electrode body 20.

  At the open end of the battery can 11, a battery lid 14, a safety valve mechanism 15 provided inside the battery lid 14 and a heat sensitive resistance element (Positive Temperature Coefficient; PTC element) 16 are interposed via a gasket 17. It is attached by caulking, and the inside of the battery can 11 is sealed. The battery lid 14 is made of, for example, the same material as the battery can 11.

  The safety valve mechanism 15 is electrically connected to the battery lid 14 via the heat sensitive resistance element 16, and the disk plate 15A is reversed when the internal pressure of the battery exceeds a certain level due to an internal short circuit or external heating. Thus, the electrical connection between the battery lid 14 and the wound electrode body 20 is cut off. When the temperature rises, the heat sensitive resistance element 16 limits the current by increasing the resistance value and prevents abnormal heat generation due to a large current. The gasket 17 is made of, for example, an insulating material, and asphalt is applied to the surface.

  The wound electrode body 20 is wound around a center pin 24, for example. A positive electrode lead 25 made of aluminum (Al) or the like is connected to the positive electrode 21 of the spirally wound electrode body 20, and a negative electrode lead 26 made of nickel (Ni) or the like is connected to the negative electrode 22. The positive electrode lead 25 is electrically connected to the battery lid 14 by being welded to the safety valve mechanism 15, and the negative electrode lead 26 is welded to and electrically connected to the battery can 11.

  FIG. 2 shows an enlarged part of the spirally wound electrode body 20 shown in FIG. The positive electrode 21 includes, for example, a positive electrode current collector 21A and a positive electrode mixture layer 21B provided on both surfaces of the positive electrode current collector 21A. In addition, you may make it have the area | region where the positive mix layer 21B exists only in the single side | surface of 21 A of positive electrode collectors. The positive electrode current collector 21A is made of, for example, a metal foil such as an aluminum (Al) foil.

  The positive electrode mixture layer 21B includes, for example, a positive electrode active material, and may include a conductive agent such as carbon black or graphite and a binder such as polyvinylidene fluoride as necessary. As the positive electrode active material, for example, a lithium phosphate compound having an olivine structure is used.

Examples of the lithium phosphate compound having an olivine structure include a compound represented by Formula I.
(Chemical I)
LiFe _1-y M _y PO ₄
Wherein M is selected from the group consisting of manganese (Mn), cobalt (Co), nickel (Ni), magnesium (Mg), zinc (Zn), chromium (Cr), titanium (Ti), and vanadium (V). Y is 0 ≦ y ≦ 0.8.)

  The negative electrode 22 has a negative electrode current collector 22A and a negative electrode mixture layer 22B provided on both surfaces of the negative electrode current collector 22A. In addition, you may make it have the area | region where the negative mix layer 22B exists only in the single side | surface of 22 A of negative electrode collectors. The anode current collector 22A is made of a metal foil such as a copper (Cu) foil.

  The negative electrode mixture layer 22B includes a carbon material that can be doped and dedoped with lithium, and a polymer compound having a repeating unit derived from vinylidene fluoride as a binder.

The doping with lithium and dedoped available carbon materials, specific surface area, use what is in a range of 0.5m ² / g~2m ² / g. This is because, when the specific surface area of the carbon material is larger than 2 m ² / g, a polymer compound having a weight average molecular weight of 250,000 to 350,000 cannot obtain sufficient binding properties. Such a carbon material can be obtained, for example, by heat-treating an organic material such as coal tar pitch at an appropriate temperature, and pulverizing and classifying it. The specific surface area of the carbon material is measured by a BET (Brunauer≡Emmet-Teller Method) method.

  Examples of the polymer compound having a repeating unit derived from vinylidene fluoride include a polymer compound having a structure containing a repeating unit derived from polyvinylidene fluoride or vinylidene fluoride in the main chain and having a carboxyl group in the side chain. Can be mentioned.

  The polymer compound having a repeating unit derived from vinylidene fluoride has a weight average molecular weight in the range of 250,000 to 350,000. When the weight average molecular weight is less than 250,000, the binding force is lowered, and it is difficult to produce a negative electrode having sufficient adhesive strength. The weight average molecular weight is measured as a polystyrene-equivalent molecular weight by gel permeation chromatography (GPC) using N-methylpyrrolidone (NMP) as a solvent.

  As content of the high molecular compound which has a repeating unit derived from vinylidene fluoride, it is in the range of 3 wt%-7 wt% with respect to the negative mix layer 22B from the point which can obtain more outstanding cycling characteristics. Is preferred. It is considered that sufficient binding properties are maintained when the content of the polymer compound having a repeating unit derived from vinylidene fluoride is 3 wt% to 7 wt%. When the content of the polymer compound having a repeating unit derived from vinylidene fluoride is increased in order to increase the adhesive strength, it is considered that lithium migration is inhibited, and thus the load characteristics are deteriorated.

  As the separator 23, for example, a polyethylene porous film, a polypropylene porous film, a synthetic resin nonwoven fabric, or the like can be used. The separator 23 is impregnated with an electrolytic solution that is a liquid electrolyte.

  The electrolytic solution includes a liquid solvent, for example, a nonaqueous solvent such as an organic solvent, and an electrolyte salt dissolved in the nonaqueous solvent.

  The non-aqueous solvent preferably contains at least one of cyclic carbonates such as ethylene carbonate and propylene carbonate. This is because the cycle characteristics can be improved. In particular, it is preferable to mix and contain ethylene carbonate and propylene carbonate because cycle characteristics can be further improved.

  The non-aqueous solvent preferably contains at least one of chain carbonates such as diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, and methyl propyl carbonate. This is because the cycle characteristics can be further improved.

  The non-aqueous solvent preferably further contains at least one of 2,4-difluoroanisole and vinylene carbonate. This is because 2,4-difluoroanisole can improve discharge capacity, and vinylene carbonate can further improve cycle characteristics. In particular, it is more preferable that they are mixed and contained because both the discharge capacity and the cycle characteristics can be improved.

  Non-aqueous solvents further include butylene carbonate, γ-butyrolactone, γ-valerolactone, those obtained by substituting some or all of the hydrogen groups of these compounds with fluorine groups, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran. 1,3-dioxolane, 4-methyl-1,3-dioxolane, methyl acetate, methyl propionate, acetonitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, 3-methoxypropyronitrile, N, N-dimethylformamide, N-methylpyrrolidinone, N-methyloxazolidinone, N, N-dimethylimidazolidinone, nitromethane, nitroethane, sulfolane, dimethyl sulfoxide, or trimethyl phosphate may be included.

  Depending on the electrode to be combined, the reversibility of the electrode reaction may be improved by using a material in which part or all of the hydrogen atoms of the substance contained in the non-aqueous solvent group are substituted with fluorine atoms. Therefore, these substances can be used as appropriate.

A lithium salt can be used as the electrolyte salt. Examples of the lithium salt include LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiSbF ₆ , LiClO ₄ , LiB (C ₆ H ₅ ) ₄ , LiCH ₃ SO ₃ , LiCF ₃ SO ₃ , LiN (SO ₂ CF ₃ ) ₂ , LiC (SO ₂ CF ₃ ) ₃ , LiAlCl ₄ , LiSiF ₆ , LiCl, LiBF ₂ (ox) [lithium difluorooxalate borate], LiBOB (lithium bisoxalate borate), LiBr, etc. are suitable, and among these, Any one kind or a mixture of two or more kinds is used. Among them, LiPF ₆ is preferable because it can obtain high ion conductivity and can improve cycle characteristics.

  This secondary battery can be manufactured, for example, as described below. First, for example, a positive electrode active material, a conductive agent, and a binder are mixed to prepare a positive electrode mixture, and the positive electrode mixture is dispersed in a solvent such as N-methylpyrrolidone to obtain a positive electrode mixture slurry. . Subsequently, the positive electrode mixture slurry is applied to the positive electrode current collector 21A and the solvent is dried. Then, the positive electrode mixture layer 21B is formed by compression molding using a roll press or the like, and the positive electrode 21 is manufactured.

  Further, for example, the above-described carbon material and a binder are mixed to prepare a negative electrode mixture, and this negative electrode mixture is dispersed in a solvent such as N-methylpyrrolidone to obtain a negative electrode mixture slurry. Subsequently, the negative electrode mixture slurry is applied to the negative electrode current collector 22A and the solvent is dried. Then, the negative electrode mixture layer 22B is formed by compression molding using a roll press or the like, and the negative electrode 22 is manufactured.

  Next, the positive electrode lead 25 is attached to the positive electrode current collector 21 by welding or the like, and the negative electrode lead 26 is attached to the negative electrode current collector 22 by welding or the like. After that, the positive electrode 21 and the negative electrode 22 are wound through the separator 23, and the tip of the positive electrode lead 25 is welded to the safety valve mechanism 15, and the tip of the negative electrode lead 26 is welded to the battery can 11. The positive electrode 21 and the negative electrode 22 are sandwiched between a pair of insulating plates 12 and 13 and stored in the battery can 11.

  After the positive electrode 21 and the negative electrode 22 are accommodated in the battery can 11, the electrolyte solution described above is injected into the battery can 11 and impregnated in the separator 23. After that, the battery lid 14, the safety valve mechanism 15, and the heat sensitive resistance element 16 are fixed to the opening end of the battery can 11 by caulking through the gasket 17. As described above, the secondary battery shown in FIG. 1 can be manufactured.

  In this secondary battery, when charged, for example, lithium ions are released from the positive electrode 21 and inserted in the negative electrode 22 through the electrolytic solution. When discharging is performed, for example, lithium ions are released from the negative electrode 22 and are inserted in the positive electrode 21 through the electrolytic solution.

  Specific embodiments of the present invention will be described in detail. However, the present invention is not limited to these examples.

<Example 1>
The coal tar pitch was heat-treated at 2800 ° C. in an inert gas atmosphere and classified to obtain a carbon material having a specific surface area of 2.0 m ² / g.

  93 parts by mass of this carbon material, 7 parts by mass of polyvinylidene fluoride having a weight average molecular weight of 350,000 as a binder, and N-methyl-2-pyrrolidone outside the quantity were kneaded to obtain a negative electrode mixture paint. This negative electrode mixture paint was applied to both sides of a copper foil having a thickness of 15 μm, dried and pressed to prepare a strip-like negative electrode.

A predetermined amount of LiCO ₃ , FeSO ₄ .7H ₂ O, and NH ₄ H ₂ PO ₄ is mixed, and the mixed powder and carbon black are mixed at a weight ratio of 97: 3. And dry mixing for 10 hours. The mixed powder was baked at 550 ° C. in a nitrogen atmosphere to obtain a lithium phosphate compound having an olivine structure represented by LiFePO ₄ coated with carbon.

  85 parts by mass of this lithium phosphate compound, 10 parts by mass of polyvinylidene fluoride, 5 parts by mass of artificial graphite, and N-methyl-2-pyrrolidone outside the quantity were kneaded to obtain a positive electrode mixture paint. This positive electrode mixture paint was applied on both sides of an aluminum foil having a thickness of 15 μm, dried and pressed to prepare a strip-like positive electrode.

A polypropylene microporous film having a thickness of 25 μm was wound between the positive electrode and the negative electrode, and LiPF ₆ 1 mol / l was dissolved in a mixed solvent in which ethylene carbonate and dimethyl carbonate were mixed in an equal volume. A cylindrical cell of Example 1 having a capacity of 1.1 Ah and 18650 size was prepared together with a water electrolyte in a metal case having a diameter of 18 mm and a height of 65 mm.

<Example 2>
The coal tar pitch was heat-treated at 2800 ° C. in an inert gas atmosphere and classified to obtain a carbon material having a specific surface area of 0.5 m ² / g. A cylindrical cell of Example 2 was produced in the same manner as Example 1 except that this carbon material was used at the time of producing the negative electrode.

<Example 3>
The cylindrical cell of Example 3 was prepared in the same manner as in Example 1 except that the amount of the carbon material was 97 parts by mass and the amount of polyvinylidene fluoride having a weight average molecular weight of 350,000 was 3 parts by mass when the negative electrode was produced. Produced.

<Example 4>
A cylindrical cell of Example 4 was produced in the same manner as in Example 1 except that polyvinylidene fluoride having a weight average molecular weight of 250,000 was used as the binder during the production of the negative electrode.

<Example 5>
The cylindrical cell of Example 5 was prepared in the same manner as in Example 1 except that the amount of the carbon material was 90 parts by mass and the amount of polyvinylidene fluoride having a weight average molecular weight of 350,000 was 10 parts by mass when the negative electrode was produced. Produced.

<Example 6>
A predetermined amount of Li ₂ CO ₃ , MnCO ₃ , FeSO ₄ .7H ₂ O and NH ₄ H ₂ PO ₄ is mixed, and the mixed powder and carbon black are mixed at a weight ratio of 97: 3. After mixing, dry mixing was performed for 10 hours in a ball mill. This mixed powder was baked at 550 ° C. in a nitrogen atmosphere to obtain a MnFe olivine positive electrode active material represented by LiMn _0.7 Fe _0.3 PO ₄ . 85 parts by mass of this MnFe olivine positive electrode active material, 10 parts by mass of polyvinylidene fluoride, 5 parts by mass of artificial graphite, and N-methyl-2-pyrrolidone outside the quantity were kneaded to obtain a positive electrode mixture paint. At the time of producing the negative electrode, the amount of the carbon material was 95 parts by mass, and the amount of the polyvinylidene fluoride having a weight average molecular weight of 350,000 was 5 parts by mass. Except for the above, a cylindrical cell of Example 6 was produced in the same manner as Example 1.

<Comparative Example 1>
A carbon material having a specific surface area of 2.5 m ² / g was obtained by subjecting the coal tar pitch to heat treatment at 2800 ° C. in an inert gas atmosphere and then classification. A cylindrical cell of Comparative Example 1 was produced in the same manner as in Example 1 except that this carbon material was used when producing the negative electrode.

<Comparative example 2>
At the time of producing the negative electrode, except that polyvinylidene fluoride having a weight average molecular weight of 500,000 was used as a binder, the amount of carbon material was 97 parts by mass, and the amount of polyvinylidene fluoride having a weight average molecular weight of 500,000 was 3 parts by mass A cylindrical cell of Comparative Example 2 was produced in the same manner as Example 1.

<Comparative Example 3>
At the time of producing the negative electrode, the amount of the carbon material was 95 parts by mass, and the amount of the polyvinylidene fluoride having a weight average molecular weight of 350,000 was 5 parts by mass. As a positive electrode active material, 95 parts by mass of LiCoO _2, 3 parts by mass of polyvinylidene fluoride, 2 parts by mass of artificial graphite, and N-methyl-2-pyrrolidone outside the amount were kneaded to obtain a positive electrode mixture paint. Except for the above, a cylindrical cell of Comparative Example 3 was produced in the same manner as Example 1.

<Comparative example 4>
A cylindrical cell of Comparative Example 4 was prepared in the same manner as Comparative Example 3 except that polyvinylidene fluoride having a weight average molecular weight of 500,000 was used as the binder during the production of the negative electrode.

<Comparative Example 5>
A predetermined amount of Li ₂ CO ₃ , MnCO ₃ , FeSO ₄ .7H ₂ O and NH ₄ H ₂ PO ₄ is mixed, and the mixed powder and carbon black are mixed at a weight ratio of 97: 3. After mixing, dry mixing was performed for 10 hours in a ball mill. This mixed powder was baked at 550 ° C. in a nitrogen atmosphere to obtain a MnFe olivine positive electrode active material represented by LiMn _0.7 Fe _0.3 PO ₄ . 85 parts by mass of this MnFe olivine positive electrode active material, 10 parts by mass of polyvinylidene fluoride, 5 parts by mass of artificial graphite, and N-methyl-2-pyrrolidone outside the quantity were kneaded to obtain a positive electrode mixture paint. Except for the above, a cylindrical cell of Comparative Example 5 was produced in the same manner as Comparative Example 2.

(Cycle characteristic evaluation)
For the cylindrical cells of Examples 1 to 5, Comparative Example 1 and Comparative Example 2, constant current and constant voltage charging (2A 3.6V 0.1Acut) and constant current discharging (7A 2.0V) are repeated, respectively. A cycle test was performed, and the discharge capacity maintenance rate of the discharge capacity at 500 cycles with respect to the discharge capacity at 1 cycle was determined. In addition, with respect to the cylindrical cells of Example 6 and Comparative Examples 3 to 5, a cycle test in which constant current and constant voltage charging (2A 4.2V 0.1Acut) and constant current discharging (7A 3.0V) are repeated, respectively. The discharge capacity maintenance rate of the discharge capacity at 500 cycles with respect to the discharge capacity at 1 cycle was determined. The obtained discharge capacity maintenance ratio was summarized as a bar graph. FIG. 3 shows a graph summarizing the cycle capacity retention rates of Examples 1 to 6 and Comparative Examples 1 to 5. Table 1 summarizes the specific surface area of the carbon material, the weight average molecular weight of the polymer compound, and the like.

As shown in FIG. 3, when Examples 1 to 4 and Example 6 are compared with Comparative Examples 1 to 2, the specific surface area is 0 when LiFePO ₄ having an olivine structure is used for the positive electrode. It can be confirmed that excellent cycle characteristics can be obtained when a negative electrode containing a carbon material of 0.5 m ² / g to ² m ² / g and a polyvinylidene fluoride having a weight average molecular weight of 250,000 to 350,000 is used. It was.

Further, according to comparison between Comparative Example 3 and Comparative Example 4 in which the positive electrode active material was LiCoO ₂ , there was almost no difference in cycle characteristics. This is presumably because the effect of the difference in the negative electrode on the cycle characteristics was small because the constant current region during charging was shorter than that of LiFePO ₄ .

Similarly, as can be seen from the comparison between Example 6 and Comparative Example 5, when LiMn _0.7 Fe _0.3 PO ₄ is used as the positive electrode active material, there is an effect of improving the cycle characteristics, but LiFePO ₄ is used as the positive electrode active material. It turned out that the improvement effect as used is not obtained.

  From Example 1, Example 3, and Example 5, it was found that the content of polyvinylidene fluoride is preferably in the range of 3 wt% to 7 wt% with respect to the negative electrode mixture layer.

  The present invention is not limited to the above-described embodiments of the present invention, and various modifications and applications are possible without departing from the spirit of the present invention. For example, in the above-described embodiment, a cylindrical battery has been described as an example. However, the present invention is not limited to this, and for example, a metal for an exterior material such as a square battery, a coin battery, a button battery, or the like. Various shapes and sizes, such as a battery using a container or the like, or a battery using a laminate film as an exterior material such as a thin battery, can also be used.

  For example, instead of the electrolytic solution, another electrolyte, for example, a gel electrolyte in which the electrolytic solution is held in a polymer compound may be used. The electrolyte solution (that is, liquid solvent, electrolyte salt, and additive) is as described above. Examples of the polymer compound include polyacrylonitrile, polyvinylidene fluoride, and a copolymer of polyvinylidene fluoride and polyhexafluoropropylene. , Polytetrafluoroethylene, polyhexafluoropropylene, polyethylene oxide, polypropylene oxide, polyphosphazene, polysiloxane, polyvinyl acetate, polyvinyl alcohol, polymethyl methacrylate, polyacrylic acid, polymethacrylic acid, styrene-butadiene rubber, nitrile -Butadiene rubber, polystyrene, polycarbonate. In particular, in consideration of electrochemical stability, polyacrylonitrile, polyvinylidene fluoride, polyhexafluoropropylene, polyethylene oxide, and the like are preferable.

  Examples of other electrolytes include solid polymer electrolytes using ion conductive polymers, and inorganic solid electrolytes using ion conductive inorganic materials. These can be used alone or in combination with other electrolytes. Also good. Examples of the polymer compound that can be used for the polymer solid electrolyte include polyether, polyester, polyphosphazene, and polysiloxane. Examples of the inorganic solid electrolyte include ion conductive ceramics, ion conductive crystals, and ion conductive glass.

It is sectional drawing showing the structure of the nonaqueous electrolyte battery by one Embodiment of this invention. It is sectional drawing which expands and represents a part of winding electrode body shown in FIG. It is the graph which put together the capacity | capacitance maintenance factor at the time of 500 cycles of Example 1- Example 6 and Comparative Examples 1-5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Battery can 12, 13 ... Insulating plate 14 ... Battery cover 15 ... Safety valve mechanism 16 ... Thermal resistance element 17 ... Gasket 20 ... Winding electrode body 21 ... Positive electrode 21A ... Positive electrode current collector 21B ... Positive electrode mixture layer 22 ... Negative electrode 22A ... Negative electrode current collector 22B ... Negative electrode mixture layer 23 ... Separator 24 ... Center pin 25 ... Positive electrode lead 26 ... Negative electrode lead

Claims (4)

A positive electrode including a lithium phosphate compound having an olivine structure, a negative electrode including a carbon material capable of doping and undoping lithium and a binder, and a non-aqueous electrolyte,
The specific surface area of the carbon material is a 0.5m ² / g~2m ² / g,
The non-aqueous electrolyte battery, wherein the binder includes a polymer compound having a repeating unit derived from vinylidene fluoride having a weight average molecular weight of 250,000 to 350,000. The lithium phosphate compound having an olivine structure, a non-aqueous electrolyte battery according to claim 1, wherein it is LiFePO _4. The nonaqueous electrolyte battery according to claim 1, wherein the polymer compound is contained in an amount of 3 wt% to 7 wt% in the negative electrode mixture layer. 2. The nonaqueous electrolyte battery according to claim 1, wherein the polymer compound contains a repeating unit derived from vinylidene fluoride in the main chain and has a carboxyl group in the side chain.

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