JP2009054480A - Nonaqueous electrolyte battery and battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-aqueous electrolyte battery equipped with a separator based on paper with a high tensile strength and reduced contraction in drying. <P>SOLUTION: This is equipped with an armoring material, an electrode group which is housed in this armoring material and has a positive electrode, a negative electrode containing a negative electrode active material in which an Li storage potential is 0.4 V (vs. Li/Li<SP>+</SP>) or more, and a non-aqueous electrolyte immersed at least into this electrode group. The separator is made of at least one paper selected from either cellulose or natural fiber pulp, and has a lengthy shape wound around together with the positive electrode and the negative electrode, or folded in zigzag. This has the lengthy shape and has a region containing a thermally fused resin at its end part along the longitudinal direction, and at least a part of the region containing the thermally fused resin which is mutually overlapped is thermally fused. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a non-aqueous electrolyte battery and a battery pack using a plurality of non-aqueous electrolyte batteries.

  With the miniaturization of personal computers, video cameras, mobile phones, etc., in the fields of information-related equipment and communication equipment, non-aqueous electrolyte batteries with high energy density have been put into practical use as power sources for these equipment, and have come to be widely used. Yes. On the other hand, in the field of automobiles, development of electric vehicles is urgently caused by environmental problems and resource problems, and non-aqueous electrolyte batteries are being studied as power sources for electric vehicles.

  A secondary battery used for a power source for an electric vehicle is required to have a high energy density, that is, a large discharge capacity per unit weight or unit volume and a long charge / discharge cycle life because of its use. Along with the increase in size of batteries, cost reduction is also an important issue.

  Cellulosic paper separators are being studied for cost reduction of non-aqueous electrolyte batteries. However, in the process of winding the paper separator together with the positive electrode and the negative electrode in a spiral manner or folding it into a ninety-nine shape, there is a high possibility that breakage will occur frequently, making it difficult to manufacture the electrode group. There are also concerns about loosening of the winding due to shrinkage during drying and an increase in the short-circuit defect rate.

  For this reason, Patent Document 1 discloses a non-aqueous battery in which a separator in which natural fibers are mixed with 10% by weight or more of beating regenerated cellulose fibers such as polynosic rayon and solvent-spun rayon is interposed between electrodes. Yes.

However, a separator obtained by mixing regenerated cellulose fibers with natural fibers cannot provide sufficient strength, resulting in frequent breaks and short-circuit defects.
Japanese Patent No. 3661104

  An object of the present invention is to provide a non-aqueous electrolyte battery including a paper-based separator having high tensile strength and reduced shrinkage during drying, and a battery pack including a plurality of the non-aqueous electrolytic batteries. To do.

According to the first aspect of the present invention, an electrode having an exterior material, a negative electrode containing a positive electrode, a negative electrode active material having a Li occlusion potential of 0.4 V (vs. Li / Li ⁺ ) or more, and housed in the exterior material A group and at least a nonaqueous electrolyte impregnated in the electrode group,
The separator is made of at least one paper selected from cellulose and natural fiber pulp, is wound with the positive electrode and the negative electrode, or has a long shape, and is folded in the longitudinal direction. There is provided a non-aqueous electrolyte battery characterized in that it has a heat-sealing resin-containing region at both ends along the line and at least a part of the portions of the heat-sealing resin-containing region overlapping each other is heat-sealed.

  According to a second aspect of the present invention, there is provided a battery pack comprising a plurality of the nonaqueous electrolyte secondary batteries.

  According to the present invention, a separator based on paper having high tensile strength and reduced shrinkage at the time of drying is provided, the separator breakage, the short-circuit defect rate is reduced, and further, the twist associated with the cycle is prevented and the cycle is reduced. A nonaqueous electrolyte battery having an improved life and a battery pack including a plurality of the nonaqueous electrolyte batteries can be provided.

  Hereinafter, nonaqueous electrolyte batteries and battery packs according to embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol shall be attached | subjected to a common structure through embodiment, and the overlapping description is abbreviate | omitted. Each figure is a schematic diagram for promoting explanation and understanding of the invention, and its shape, dimensions, ratio, and the like are different from those of an actual device. However, these are in consideration of the following explanation and known techniques. The design can be changed as appropriate.

(First embodiment)
The nonaqueous electrolyte battery according to the first embodiment includes an exterior material, a negative electrode and a separator that are housed in the exterior material, and include a positive electrode, a negative electrode active material having a Li storage potential of 0.4 V (vs. Li / Li ⁺ ) or higher. And an electrode group having at least a nonaqueous electrolyte impregnated in the electrode group. The separator is made of at least one paper selected from cellulose and natural fiber pulp, and has a long shape that is wound together with the positive electrode and the negative electrode or folded ninety-nine. In such a separator, at both ends along the longitudinal direction, there are heat-sealing resin-containing regions, and at least some of the portions of the heat-sealing resin-containing regions that overlap each other are heat-sealed.

  Hereinafter, the exterior material, the separator, the positive electrode, the negative electrode, and the nonaqueous electrolyte will be described.

1) Exterior material As the exterior material, a laminate film having a thickness of 0.5 mm or less or a metal container having a thickness of 1.0 mm or less is used. The metal container is more preferably 0.5 mm or less in thickness.

  Examples of the shape of the exterior material include a flat type (thin type), a square type, a cylindrical type, a coin type, and a button type. Examples of the exterior material include a small battery exterior material loaded on a portable electronic device or the like, and a large battery exterior material loaded on a two-wheeled or four-wheeled vehicle, depending on the battery size.

  As the laminate film, a multilayer film in which a metal layer is interposed between resin films is used. The metal layer is preferably an aluminum foil or an aluminum alloy foil for weight reduction. As the resin film, for example, a polymer material such as polypropylene (PP), polyethylene (PE), nylon, polyethylene terephthalate (PET) can be used. The laminate film can be molded into the shape of an exterior material by sealing by heat sealing.

  The metal container is made of aluminum or an aluminum alloy. As the aluminum alloy, an alloy containing elements such as magnesium, zinc and silicon is preferable. In aluminum or an aluminum alloy, it is preferable that the content of transition metals such as iron, copper, nickel and chromium be 100 ppm or less in order to drastically improve long-term reliability and heat dissipation in a high temperature environment.

  The metal container made of aluminum or an aluminum alloy has an average crystal grain size of 50 μm or less, more preferably 30 μm or less, and still more preferably 5 μm or less. By setting the average crystal grain size to 50 μm or less, the strength of a metal container made of aluminum or an aluminum alloy can be dramatically increased, and the container can be made thinner. As a result, it is possible to realize a non-aqueous electrolyte battery suitable for in-vehicle use and the like that is lightweight, has high output, and has long-term reliability.

2) Separator The separator that is a feature of the nonaqueous electrolyte battery according to the first embodiment is made of at least one paper selected from cellulose and natural fiber pulp as described above, and is wound together with the positive electrode and the negative electrode. Or it has a long shape that is folded ninety-nine.

  In such a separator, at both ends along the longitudinal direction, there are heat-sealing resin-containing regions, and at least some of the portions of the heat-sealing resin-containing regions that overlap each other are heat-sealed. This heat fusion is performed in a hot press for further increasing the density of the electrode group when the separator is wound together with the positive electrode and the negative electrode, or when the electrode group is manufactured by folding.

  As the heat-fusible resin, for example, polyethylene, polypropylene, polystyrene, nylon or the like can be used.

  It is preferable from the viewpoint of improving the tensile strength that the heat-sealing resin-containing region is formed in a band shape having the same width at both end portions along the longitudinal direction of the separator.

  The area of the heat-sealing resin-containing region is preferably 4% or more and 50% or less with respect to the total area of the separator. If the area of the heat-sealing resin-containing region is less than 4%, it is difficult to sufficiently increase the tensile strength. On the other hand, if the area of the heat-sealing resin-containing region exceeds 50%, the lithium ion transmission efficiency is substantially equivalent to that of the conventional porous polypropylene film, and the effect of improving the large current discharge characteristics by the paper separator is achieved. It may be difficult to do. A more preferable area of the heat-sealing resin-containing region is 10% or more and 30% or less with respect to the total area of the separator.

  The separator described above is manufactured by, for example, the following method.

  First, at least one paper raw material selected from cellulose and natural fiber pulp is made by a conventional method, and wound around a core material to obtain a paper roll. While the paper is being unwound from the paper roll, it is cut along the length direction to obtain a long paper having the width of the final separator, and it is wound around a core material again to obtain a paper separator roll. Subsequently, the core material is pulled out from the scroll, and one end in the axial direction of the scroll is immersed in the heat-fusible resin solution, taken out, and then dried to one end in the axial direction of the scroll, that is, one end along the longitudinal direction of the separator. A heat-sealing resin-containing region is formed. Subsequently, the other end in the axial direction of the scroll is again immersed in the heat-fusible resin solution, taken out, dried, and heated to the other end in the axial direction of the scroll, that is, the other end along the longitudinal direction of the separator. Producing a separator made of at least one paper selected from cellulose and natural fiber pulp by forming a fusion resin-containing region, having a long shape and having heat-fusion resin-containing regions at both ends along the longitudinal direction To do.

  For example, in the case of polyethylene, the heat-fusible resin solution is preferably heated to about 180 ° C. and dissolved.

3) Negative electrode The negative electrode is supported on one or both sides of the negative electrode current collector and the negative electrode current collector, and the negative electrode active material, conductive agent and binder having a Li occlusion potential of 0.4 V (vs. Li / Li ⁺ ) or higher. And a negative electrode active material-containing layer containing an agent.

In a negative electrode active material (eg, graphite, lithium metal, etc.) that occludes lithium at a potential lower than 0.4 V (vs. Li ^/ Li ⁺ ), if lithium ion is repeatedly input and output with a large current, lithium metal is not formed on the negative electrode surface. Precipitates and grows in dendritic form. Since the separator has a void having a large diameter, metal lithium grown in a dendritic shape easily penetrates the separator, and thus there is a risk of causing an internal short circuit during input / output (charge / discharge) with a large current.

By using a negative electrode active material whose lithium occlusion potential is nobler than 0.4 V (vs. Li / Li ⁺ ), metal lithium deposition on the negative electrode surface is suppressed even when a large-diameter void exists in the separator. It is possible to avoid an internal short circuit during input / output with a large current. The upper limit value of the lithium storage potential is desirably 3 V (vs. Li ^/ Li ⁺ ), more preferably 2 V (vs. Li ^/ Li ⁺ ).

The negative electrode active material capable of occluding lithium at 0.4 to 3 V (vs. Li / Li ⁺ ) is preferably a metal oxide, metal sulfide, metal nitride, or alloy.

Examples of the metal oxide include titanium-containing metal composite oxides; for example, tin-based oxides such as SnB _0.4 P _0.6 O _3.1 and SnSiO ₃ ; silicon-based oxides such as SiO; and tungsten-based oxides such as WO ₃ ; Can be mentioned. Of these, titanium-containing metal composite oxides are preferable.

Examples of titanium-containing metal composite oxides include lithium-free titanium-based oxides, lithium-titanium oxides, and lithium-titanium composite oxides in which some of the constituent elements of lithium-titanium oxides are replaced with different elements during oxide synthesis. Can be mentioned. Examples of the lithium titanium oxide include lithium titanate having a spinel structure (for example, Li _{4 + x} Ti ₅ O ₁₂ (x is a value that varies depending on charge and discharge, 0 ≦ x ≦ 3)), ramsteride type lithium titanate. (For example, Li _{2 + y} Ti ₃ O ₇ (y is a value that varies depending on charge / discharge, 0 ≦ y ≦ 3) and the like. On the other hand, the molar ratio of oxygen is spinel type Li ₄ Ti ₅ O _12. Is 12 and ramsdellite-type Li ₂ Ti ₃ O ₇ is 7 as a formality, but these values can be changed by the influence of oxygen non-stoichiometry or the like.

Examples of the titanium-based oxide include metal composite oxides containing TiO ₂ , Ti, and at least one element selected from the group consisting of P, V, Sn, Cu, Ni, Co, and Fe. TiO ₂ is preferably anatase type and low crystalline having a heat treatment temperature of 300 to 500 ° C. Metal composite oxides containing at least one element selected from the group consisting of Ti and P, V, Sn, Cu, Ni, Co and Fe are, for example, TiO ₂ —P ₂ O ₅ , TiO ₂ —V ₂ O. ₅ , TiO ₂ —P ₂ O ₅ —SnO ₂ , TiO ₂ —P ₂ O ₅ —MeO (Me is at least one element selected from the group consisting of Cu, Ni, Co and Fe). . This metal composite oxide preferably has a microstructure in which a crystal phase and an amorphous phase coexist or exist alone. The metal composite oxide having a microstructure can greatly improve the cycle performance. Among these, lithium titanium oxide, metal composite oxide containing at least one element selected from the group consisting of Ti and P, V, Sn, Cu, Ni, Co, and Fe are preferable. In particular, lithium titanium oxide having a spinel structure is preferable.

Examples of the metal sulfide include titanium-based sulfides such as TiS ₂ ; molybdenum-based sulfides such as MoS ₂ ; iron-based sulfides such as FeS, FeS ₂ , and Li _x FeS ₂ (0 ≦ x ≦ 4): Can be mentioned.

Examples of the metal nitride include lithium-based nitride (for example, (Li, Me) ₃ N, where Me represents a transition metal element).

The negative electrode active material desirably has an average particle size of 1 μm or less. Moreover, it is preferable that the negative electrode active material has a specific surface area of 1 to 10 m ² / g according to the BET method by N ₂ adsorption. If the average particle size exceeds 1 μm or the specific surface area is less than 1 m ² / g, the effective area contributing to the electrode reaction may be small and the large current discharge characteristics may be deteriorated. On the other hand, if the specific surface area exceeds 10 m ² / g, the amount of reaction between the negative electrode and the nonaqueous electrolyte increases, which may cause a decrease in charge / discharge efficiency and induce gas generation during storage. If the average particle size is too small, the distribution of the non-aqueous electrolyte is biased toward the negative electrode, which may lead to depletion of the electrolyte at the positive electrode. Therefore, the lower limit is preferably set to 0.001 μm.

  The negative electrode density is desirably 2 g / cc or more.

As the conductive agent, for example, a carbonaceous material such as coke is used. The average particle size of the carbonaceous material is preferably 0.1 μm or more in order to effectively suppress gas generation, and 10 μm or less in order to construct a good conductive network. Similarly, the specific surface area of the carbonaceous material is preferably 10 m ² / g or more for constructing a good conductive network, and 100 m ² / g or less for effectively suppressing gas generation.

The binder is preferably polyvinylidene fluoride (PVdF) having a number average molecular weight of 4 × 10 ⁵ or more and 20 × 10 ⁵ or less. PVdF having such a number average molecular weight makes it possible to increase the peel strength between the current collector and the negative electrode active material layer to 0.005 N / mm or more, thereby improving the large current characteristics. If the number average molecular weight exceeds 20 × 10 ⁵ , a sufficient peel strength can be obtained, but the viscosity of the coating solution becomes too high, and it becomes difficult to carry out coating properly. More preferably, the number average molecular weight of polyvinylidene fluoride is 5 × 10 ⁵ or more and 10 × 10 ⁵ or less.

  The mixing ratio of the negative electrode active material, the conductive agent and the binder is preferably 67 to 97.5% by weight of the negative electrode active material, 2 to 28% by weight of the conductive agent and 0.5 to 5% by weight of the binder. When the conductive agent is blended at a ratio of 2% by weight or more, an excellent large current characteristic due to high current collecting performance can be obtained, and by blending at a ratio of 28% by weight or less, the capacity can be increased. . In addition, by blending the binder at a ratio of 0.5 wt% or more, the peel strength between the current collector and the negative electrode active material layer can be 0.005 N / mm or more, and at a ratio of 5 wt% or less. By blending, an appropriate coating solution viscosity is obtained, and good coating is possible.

  The current collector is preferably an aluminum foil or an aluminum alloy foil.

  The current collector preferably has an average crystal grain size of 50 μm or less. The current collector made of aluminum foil or aluminum alloy foil having such an average crystal grain size has a drastically increased strength, so that the negative electrode can be densified with a high press pressure, and the battery capacity can be increased. Can be increased. In addition, since the current collector can be prevented from melting and corroding in an overdischarge cycle under a high temperature environment (40 ° C. or higher), an increase in negative electrode impedance can be suppressed. Furthermore, output characteristics, quick charge, and charge / discharge cycle characteristics can also be improved. The average crystal grain size of the current collector is more preferably 30 μm or less, and further preferably 5 μm or less.

The average crystal grain size of the current collector is determined as follows. The structure of the current collector surface is observed with an optical microscope, and the number n of crystal grains existing within 1 mm × 1 mm is determined. Using this n, the average crystal grain area S is determined from S = 1 × 10 ⁶ / n (μm ² ). From the obtained value of S, the average crystal grain size d (μm) is calculated by the following formula (1).

d = 2 (S / π) ^1/2 (1)
Aluminum foil or aluminum alloy foil with an average crystal grain size of 50 μm or less is affected by many factors such as material composition, impurities, processing conditions, heat treatment history and annealing conditions, and the crystal grain diameter (diameter) Is adjusted by combining the above factors in the manufacturing process.

  The thickness of the aluminum foil and the aluminum alloy foil is 20 μm or less, more preferably 15 μm or less. The purity of the aluminum foil is preferably 99% or more. The aluminum alloy is preferably an alloy containing elements such as magnesium, zinc, and silicon. On the other hand, the content of transition metals such as iron, copper, nickel and chromium is preferably 1% or less.

  The negative electrode is produced, for example, by suspending a negative electrode active material, a conductive agent, and a binder in an appropriate solvent, and applying the suspension to a current collector such as an aluminum foil, drying, and pressing.

4) Positive Electrode The positive electrode includes a current collector and a positive electrode active material-containing layer that is supported on one or both surfaces of the current collector and includes a positive electrode active material and a binder (if necessary, a conductive agent).

As the positive electrode active material, various oxides, sulfides, polymers, and the like can be used. For example, manganese dioxide (MnO ₂ ), iron oxide, copper oxide, nickel oxide, lithium manganese composite oxide (for example, Li _x Mn _2). O ₄ or Li _x MnO ₂ ), lithium nickel composite oxide (eg, Li _x NiO ₂ ), lithium cobalt composite oxide (Li _x CoO ₂ ), lithium nickel cobalt composite oxide (eg, LiNi _1-y Co _y O _2). ), lithium manganese cobalt composite oxides (e.g. _{LiMn y Co 1-y O 2} ), spinel type lithium-manganese-nickel composite oxide _{(Li x Mn 2-y Ni} y O 4), lithium phosphates having an olivine structure ( Li _x FePO _4, such as _{Li x Fe 1-y Mn y} PO 4, Li x CoPO 4), iron sulfate _{(Fe 2 (SO 4) 3} ), vanadium oxide For example V ₂ O _5), and the like. In addition, conductive polymer materials such as polyaniline and polypyrrole, disulfide polymer materials, organic materials such as sulfur (S) and carbon fluoride, and inorganic materials can also be used.

More preferable positive electrode active materials can obtain a high battery voltage. For example, lithium manganese composite oxide (Li _x Mn ₂ O ₄ ), lithium nickel composite oxide (Li _x NiO ₂ ), lithium cobalt composite oxide (Li _x CoO ₂ ), lithium nickel cobalt composite oxide (Li _x Ni _1-y Co _y O ₂ ), spinel type lithium manganese nickel composite oxide (Li _x Mn _{2 -y} Ni _y O ₄ ), lithium manganese cobalt composite oxide _{(Li x Mn y Co 1-} y O 2), is such as lithium iron phosphate (Li _x FePO _4). X and y are preferably in the range of 0 to 1.

The positive electrode active material has a composition of Li _a Ni _b Co _c Mn _d O ₂ (where the molar ratios a, b, c and d are 0 ≦ a ≦ 1.1, 0.1 ≦ b ≦ 0.5, 0 ≦ It is possible to use a lithium nickel cobalt manganese composite oxide represented by c ≦ 0.9, 0.1 ≦ d ≦ 0.5).

When a non-aqueous electrolyte containing a room temperature molten salt is used, it is necessary to use lithium iron phosphate, Li _x VPO ₄ F, lithium manganese composite oxide, lithium nickel composite oxide, lithium nickel cobalt composite oxide. From the viewpoint of This is because the reactivity between the positive electrode active material and the room temperature molten salt is reduced.

  Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and fluorine-based rubber.

  Examples of the conductive agent include acetylene black, carbon black, and graphite.

  The mixing ratio of the positive electrode active material, the conductive agent and the binder is preferably 80 to 95% by weight of the positive electrode active material, 3 to 18% by weight of the conductive agent, and 2 to 17% by weight of the binder.

  The current collector is preferably an aluminum foil or an aluminum alloy foil. Like the negative electrode current collector, the average crystal grain size is 50 μm or less, more preferably 30 μm or less, and even more preferably 5 μm or less. The current collector made of an aluminum foil or aluminum alloy foil having such an average crystal grain size can dramatically increase the strength, and the positive electrode can be densified with a high press pressure. The capacity can be increased.

  Aluminum foil or aluminum alloy foil with an average crystal grain size of 50 μm or less is affected by many factors such as material composition, impurities, processing conditions, heat treatment history and annealing conditions, and the crystal grain diameter (diameter) Is adjusted by combining the above factors in the manufacturing process.

  The thickness of the aluminum foil and the aluminum alloy foil is 20 μm or less, more preferably 15 μm or less. The purity of the aluminum foil is preferably 99% or more. As the aluminum alloy, an alloy containing elements such as magnesium, zinc and silicon is preferable. On the other hand, the content of transition metals such as iron, copper, nickel and chromium is preferably 1% or less.

  The positive electrode density is desirably 3 g / cc or more.

  For the positive electrode, for example, a positive electrode active material and a binder (a conductive agent if necessary) are suspended in an appropriate solvent, and the slurry prepared by suspending the slurry is applied to a positive electrode current collector and dried to contain a positive electrode active material. After the layer is produced, it is produced by applying a press. In addition, the positive electrode active material, the positive electrode conductive agent, and the binder may be formed in a pellet shape and used as the positive electrode active material-containing layer.

5) Nonaqueous electrolyte A liquid nonaqueous electrolyte can be used for the nonaqueous electrolyte.

  The liquid nonaqueous electrolyte is prepared, for example, by dissolving the electrolyte in an organic solvent.

Examples of the electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium hexafluoroarsenide (LiAsF ₆ ), and trifluorometasulfonic acid. Examples include lithium salts such as lithium (LiCF ₃ SO ₃ ) and bistrifluoromethylsulfonylimitolithium [LiN (CF ₃ SO ₂ ) ₂ ].

  The electrolyte is preferably dissolved in the range of 0.5 to 2.5 mol / L with respect to the organic solvent.

  Examples of the organic solvent include cyclic carbonates such as ethylene carbonate (EC), propylene carbonate (PC), and vinylene carbonate (VC), and chain carbonates such as dimethyl carbonate (DMC), methyl ethyl carbonate (MEC), and diethyl carbonate (DEC). , Tetrahydrofuran (THF), cyclic ethers such as 2methyltetrahydrofuran (2MeTHF), chain ethers such as dimethoxyethane (DME), γ-butyrolactone (BL) acetonitrile (AN), sulfolane (SL), and the like. These organic solvents can be used alone or in the form of a mixture of two or more.

  As the liquid non-aqueous electrolyte, a room temperature molten salt containing lithium ions can be used.

  The room temperature molten salt refers to a salt that is at least partially in a liquid state at room temperature, and the room temperature refers to a temperature range in which a power supply is assumed to normally operate. The temperature range in which the power supply is assumed to normally operate has an upper limit of about 120 ° C. and in some cases about 60 ° C., and a lower limit of about −40 ° C. and in some cases about −20 ° C.

As the lithium salt, a lithium salt having a wide potential window, which is generally used for a nonaqueous electrolyte battery, is used. For example, LiBF ₄ , LiPF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ), LiN (CF ₃ SC (C ₂ F ₅ SO ₂ ) ₃ etc. Although not limited thereto, these may be used alone or in combination of two or more.

  The lithium salt content is preferably 0.1 to 3.0 mol / L, particularly 1.0 to 2.0 mol / L. By setting the content of the lithium salt to 0.1 mol / L or more, the resistance of the electrolyte can be reduced, so that large current / low temperature discharge characteristics can be improved. By setting the lithium salt content to 3.0 mol / L or less, the melting point of the electrolyte can be kept low, and the liquid state can be maintained at room temperature.

The room temperature molten salt has, for example, a quaternary ammonium organic cation having a skeleton represented by the following formula (I) or an imidazolium cation having a skeleton represented by the formula (II).

However, R1, R2 in formula _{(II), C n H 2n + 1 (} n = 1~6), R3 represents H or _{C n H 2n + 1 (n} = 1~6).

  Examples of the quaternary ammonium organic cation having a skeleton represented by the formula (I) include imidazolium ions such as dialkylimidazolium and trialkylimidazolium, tetraalkylammonium ions, alkylpyridinium ions, pyrazolium ions, pyrrolidinium ions, And piperidinium ions. In particular, an imidazolium cation having a skeleton represented by the formula (II) is preferable.

  Examples of the tetraalkylammonium ion include, but are not limited to, trimethylethylammonium ion, trimethylethylammonium ion, trimethylpropylammonium ion, trimethylhexylammonium ion, and tetrapentylammonium ion.

  Moreover, as an alkyl pyridium ion, N-methyl pyridinium ion, N-ethyl pyridinium ion, N-propyl pyridinium ion, N-butyl pyridinium ion, 1-ethyl-2-methyl pyridinium ion, 1-butyl-4- Examples include methylpyridinium ion and 1-butyl-2,4dimethylpyridinium ion, but are not limited thereto.

  In addition, the normal temperature molten salt which has these cations may be used independently, or may be used in mixture of 2 or more types.

  Examples of the imidazolium cation having a skeleton represented by the formula (II) include, but are not limited to, dialkylimidazolium ions and trialkylimidazolium ions.

  Examples of the dialkylimidazolium ion include 1,3-dimethylimidazolium ion, 1-ethyl-3-methylimidazolium ion, 1-methyl-3-ethylimidazolium ion, 1-methyl-3-butylimidazolium ion, 1 -Butyl-3-methylimidazolium ion etc. are mentioned, However, It is not limited to these.

  Examples of the trialkylimidazolium ion include 1,2,3-trimethylimidazolium ion, 1,2-dimethyl-3-ethylimidazolium ion, 1,2-dimethyl-3-propylimidazolium ion, and 1-butyl-2. , 3-dimethylimidazolium ion and the like, but are not limited thereto.

  In addition, the normal temperature molten salt which has these cations may be used independently, or may mix and use 2 or more types.

  An example of the nonaqueous electrolyte battery according to the first embodiment will be described in detail with reference to FIGS. FIG. 1 is a cross-sectional view showing a lithium ion secondary battery which is an example of a nonaqueous electrolyte battery according to the first embodiment, FIG. 2 is an enlarged cross-sectional view showing part A of FIG. 1, and FIG. 3 is a separator of FIG. FIG.

  The flat wound electrode group 1 is housed in a bag-shaped exterior material 2 made of a laminate film in which an aluminum foil is interposed between two resin layers. The flat wound electrode group 1 is formed by winding a laminate of the negative electrode 3, the separator 4, the positive electrode 5, and the separator 4 in this order from the outside in a spiral shape and press-molding. The outermost negative electrode 3 has a structure in which a negative electrode layer 3b containing a negative electrode active material is formed on one surface on the inner surface side of a negative electrode current collector 3a as shown in FIG. The negative electrode layer 3b is formed on both surfaces of the body 3a. The positive electrode 5 is configured by forming a positive electrode layer 3b on both surfaces of a positive electrode current collector 5a. As shown in FIG. 3, the separator 4 is made of, for example, cellulose paper. The separator 4 has heat-sealing resin-containing regions 4 a at both ends along the longitudinal direction, and at least a part of the portions of the heat-sealing resin-containing regions 4 a that overlap each other. Is heat-sealed.

  In the vicinity of the outer peripheral end of the wound electrode group 1, the negative electrode terminal 6 is connected to the negative electrode current collector 3 a of the outermost negative electrode 3, and the positive electrode terminal 7 is connected to the positive electrode current collector 5 a of the inner positive electrode 5. . The negative electrode terminal 6 and the positive electrode terminal 7 are extended from the same opening of the bag-shaped exterior material 2 to the outside in the same direction. For example, the liquid non-aqueous electrolyte is injected from the opening of the bag-shaped exterior material 2. The wound electrode group 1 and the liquid nonaqueous electrolyte are completely sealed by heat-sealing the opening of the bag-shaped outer packaging material 2 with the negative electrode terminal 6 and the positive electrode terminal 7 interposed therebetween.

  For the negative electrode terminal, for example, a material having electrical stability and conductivity in a range where the potential with respect to the lithium ion metal is 1.0 V or more and 3.0 V or less can be used. Specifically, aluminum or an aluminum alloy containing an element such as Mg, Ti, Zn, Mn, Fe, Cu, or Si can be given. In order to reduce the contact resistance with the negative electrode current collector, the negative electrode terminal is preferably made of the same material as the negative electrode current collector.

  For the positive electrode terminal, a material having electrical stability and conductivity in a range where the potential with respect to the lithium ion metal is 3.0 V to 4.25 V can be used. Specifically, aluminum or an aluminum alloy containing an element such as Mg, Ti, Zn, Mn, Fe, Cu, or Si can be given. The positive electrode terminal is preferably made of the same material as that of the positive electrode current collector in order to reduce contact resistance with the positive electrode current collector.

  The nonaqueous electrolyte battery according to the first embodiment is not limited to the one shown in FIGS. 1 and 2 described above, and may be a rectangular flat battery having a rectangular outer can as an outer covering shown in FIGS. 4 and 5, for example. . 4 is a partially cutaway perspective view showing a rectangular flat battery, and FIG. 5 is an enlarged sectional view of a portion B in FIG.

  The flat electrode group 11 is housed in a metal bottomed rectangular cylinder 12. The metal rectangular lid 13 is attached to the opening of the bottomed rectangular cylinder 12 and constitutes a rectangular outer can. As shown in FIG. 5, the electrode group 11 is produced by winding the positive electrode 14 and the negative electrode 15 in a spiral shape so that the separator 16 is positioned on the outer peripheral surface with the separator 16 interposed therebetween, and press molding. The positive electrode 14 includes, for example, a current collector 14a and a positive electrode active material-containing layer 14b formed on both surfaces of the current collector 14a. The positive electrode lead tab 17 is integrally connected to the current collector 14 a of the positive electrode 14. The negative electrode 15 includes, for example, a current collector 15a and a negative electrode active material-containing layer 15b formed on both surfaces of the current collector 15a. The negative electrode lead tab 18 is integrally connected to the current collector 15 a of the negative electrode 15. As in FIG. 3 described above, the separator 16 is made of, for example, cellulose paper, has heat-sealing resin-containing regions at both ends along the longitudinal direction, and at least some of the portions of the heat-sealing resin-containing regions that overlap each other. It is heat-sealed.

  The nonaqueous electrolytic solution is accommodated in the bottomed rectangular cylinder 12. For example, the plate-like positive electrode terminal 19 is inserted into the lid body 13. A positive electrode lead tab 17 is connected near the end of the positive electrode terminal 19 located in the bottomed rectangular cylinder 12. For example, the plate-like negative electrode terminal 20 is inserted into the lid 13 by, for example, a hermetic seal with a glass material 21 interposed. A negative electrode lead tab 18 is connected near the end of the negative electrode terminal 20 located in the bottomed rectangular cylinder 12.

  The illustrated nonaqueous electrolyte battery uses a wound electrode group in which the separator is wound together with the positive electrode and the negative electrode. However, the separator is folded into ninety nines, and the positive electrode and the negative electrode are alternately arranged at the folded portions. A type of electrode group may be used.

  The nonaqueous electrolyte battery according to the first embodiment described above is made of at least one paper selected from cellulose and natural fiber pulp, and is wound together with a positive electrode and a negative electrode, or is folded ninety times. A separator having a scale shape and having a heat-sealing resin-containing region at an end portion along the longitudinal direction and having at least a part of the portions of the heat-sealing resin-containing region overlapping each other is provided. That is, since the separator disposed between the positive electrode and the negative electrode is made of at least one paper selected from cellulose and natural fiber pulp, the passage and movement of, for example, lithium ions from the positive electrode to the negative electrode and from the negative electrode to the positive electrode are extremely smooth. Therefore, the large current discharge characteristics can be improved.

The resistance of the separator increases as it is exposed to a high temperature environment or a high potential (oxidizing atmosphere) environment. That is, the resistance of the separator increases due to the deterioration of the separator itself and the deposition of reaction products (separator clogging) accompanying the side reaction that occurs on the electrode surface, which reduces the battery performance. At this time, when the negative electrode potential is low, a part of the decomposition product generated at the interface between the positive electrode and the nonaqueous electrolyte is likely to be deposited on the negative electrode surface. Therefore, by using a negative electrode containing a negative electrode active material having a Li storage potential of 0.4 V (vs. Li / Li ⁺ ) or higher, the potential of the negative electrode can be increased. Precipitation of substances can be suppressed, and blockage of voids in contact with the negative electrode of the separator can be suppressed, and also blockage of voids due to alteration of the separator itself can be suppressed. As a result, it is possible to provide a non-aqueous electrolyte battery in which a large current discharge performance is remarkably suppressed even when exposed to a high temperature environment for a long time in a charged state.

  Further, by forming a heat-sealing resin-containing region at the end portion along the longitudinal direction of the separator and heat-sealing at least a part of the portions of the heat-sealing resin-containing region that overlap each other, the tensile strength is increased and drying is performed. Time shrinkage can be reduced. For this reason, it is possible to reduce the breakage rate and short-circuit defect rate of the separator, and it is possible to prevent the twist caused by the cycle. As a result, a non-aqueous electrolyte battery with high reliability and improved cycle life can be provided.

  In particular, by using a separator having an area of the heat-sealing resin-containing region of 4% or more and 50% or less (more preferably 10% or more and 30% or less) with respect to the total area, a large current that is characteristic of a paper separator Since the tensile strength can be sufficiently increased while maintaining the discharge characteristics, it is possible to provide a nonaqueous electrolyte battery in which high current discharge characteristics, high reliability, and cycle life are balanced.

(Second Embodiment)
The battery pack according to the second embodiment includes a plurality of the non-aqueous electrolyte batteries (unit cells) described above, and each unit cell is electrically connected in series or in parallel.

  Such a battery pack will be described in detail with reference to FIGS. The flat battery shown in FIG. 1 can be used for the unit cell.

  A plurality of unit cells 31 composed of the flat type nonaqueous electrolyte battery shown in FIG. 1 are laminated so that the negative electrode terminal 6 and the positive electrode terminal 7 extending to the outside are aligned in the same direction, and an adhesive tape 32 is provided. The assembled battery 33 is configured by fastening at the above. These unit cells 31 are electrically connected to each other in series as shown in FIG.

  The printed wiring board 34 is disposed to face the side surface of the unit cell 31 from which the negative electrode terminal 6 and the positive electrode terminal 7 extend. As shown in FIG. 7, a thermistor 35, a protection circuit 36, and a terminal 37 for energizing external devices are mounted on the printed wiring board 34. An insulating plate (not shown) is attached to the surface of the protection circuit board 34 facing the assembled battery 33 in order to avoid unnecessary connection with the wiring of the assembled battery 33.

  The positive electrode side lead 38 is connected to the positive electrode terminal 7 located at the lowermost layer of the assembled battery 33, and the tip thereof is inserted into the positive electrode side connector 39 of the printed wiring board 34 and electrically connected thereto. The negative electrode side lead 40 is connected to the negative electrode terminal 6 located in the uppermost layer of the assembled battery 33, and the tip thereof is inserted into the negative electrode side connector 41 of the printed wiring board 34 and electrically connected thereto. These connectors 39 and 41 are connected to the protection circuit 36 through wirings 42 and 43 formed on the printed wiring board 34.

  The thermistor 35 detects the temperature of the unit cell 31, and the detection signal is transmitted to the protection circuit 36. The protection circuit 36 can cut off the plus-side wiring 44a and the minus-side wiring 44b between the protection circuit 36 and the terminal 37 for energization to an external device under a predetermined condition. The predetermined condition is, for example, when the temperature detected by the thermistor 35 is equal to or higher than a predetermined temperature. Further, the predetermined condition is when an overcharge, overdischarge, overcurrent, or the like of the unit cell 31 is detected. This detection of overcharge or the like is performed on each individual cell 21 or the entire cell 31. When detecting each single battery 31, the battery voltage may be detected, or the positive electrode potential or the negative electrode potential may be detected. In the latter case, a lithium electrode used as a reference electrode is inserted into each unit cell 31. In the case of FIG. 6 and FIG. 7, the voltage detection wiring 45 is connected to each of the single cells 31, and the detection signal is transmitted to the protection circuit 36 through the wiring 45.

  Protective sheets 46 made of rubber or resin are respectively disposed on the three side surfaces of the assembled battery 33 excluding the side surfaces from which the positive electrode terminal 7 and the negative electrode terminal 6 protrude.

  The assembled battery 33 is stored in a storage container 47 together with each protective sheet 46 and the printed wiring board 34. That is, the protective sheet 46 is disposed on each of the inner side surface in the long side direction and the inner side surface in the short side direction of the storage container 47, and the printed wiring board 34 is disposed on the inner side surface on the opposite side in the short side direction. The assembled battery 33 is located in a space surrounded by the protective sheet 46 and the printed wiring board 34. The lid 48 is attached to the upper surface of the storage container 47.

  Note that a heat-shrinkable tube may be used instead of the adhesive tape 32 for fixing the assembled battery 33. In this case, protective sheets are arranged on both side surfaces of the assembled battery, the heat shrinkable tube is circulated, and then the heat shrinkable tube is thermally contracted to bind the assembled battery.

  In such a battery pack according to the second embodiment, each single battery 31 of the assembled battery 33 includes the separator described above and has excellent large current discharge characteristics and cycle characteristics. It can be applied to in-vehicle use such as a four-wheel hybrid electric vehicle, a two-wheel to four-wheel electric vehicle, and an assist bicycle, and is particularly suitable for in-vehicle use.

  As described above, a mixed solvent in which at least two of the group consisting of propylene carbonate (PC), ethylene carbonate (EC) and γ-butyrolactone (GBL) are mixed, or a nonaqueous electrolyte containing γ-butyrolactone (GBL) By using this, a nonaqueous electrolyte battery having excellent high temperature characteristics can be obtained. A battery pack provided with an assembled battery having a plurality of such nonaqueous electrolyte batteries is particularly suitable for in-vehicle use.

  The battery packs shown in FIGS. 6 and 7 have shown the form in which the single cells 31 are connected in series, but may be connected in parallel to increase the battery capacity. The assembled battery packs can be connected in series or in parallel.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples as long as the gist of the invention is not exceeded.

(Example 1)
<Preparation of positive electrode>
First, 90% by weight of lithium cobalt oxide (LiCoO ₂ ) powder, 3% by weight of acetylene black, 3% by weight of graphite and 4% by weight of polyvinylidene fluoride (PVdF) are added to N-methylpyrrolidone (NMP) as a positive electrode active material. A slurry was prepared by mixing. The slurry was applied to both surfaces of a current collector made of an aluminum foil having a thickness of 15 μm and an average crystal particle size of 30 μm, and then dried and pressed to obtain an electrode density of 3.0 g / cm ³ and a surface roughness Ra ( A positive electrode having a +) of 0.15 μm was produced.

<Production of negative electrode>
As the negative electrode active material, lithium titanate represented by Li ₄ Ti ₅ O ₁₂ having a spinel structure with an average particle size of 0.7 μm and a Li occlusion potential of 1.55 V (vs. Li / Li ⁺ ) was prepared. This negative electrode active material, acetylene black as a conductive material, and polyvinylidene fluoride (PVdF) having a number average molecular weight of 4 × 10 ⁵ are mixed with N-methylpyrrolidone (NMP) at a weight ratio of 95: 2.5: 2.5. ) Added to the solution and mixed to prepare a slurry. The obtained slurry was applied to an aluminum foil having a thickness of 15 μm and an average crystal particle diameter of 30 μm, dried, and pressed to prepare a negative electrode having an electrode density of 2.2 g / cm ³ .

  The Li storage potential was measured by the method described below.

The negative electrode was cut into a size of 2 cm × 2 cm to obtain a working electrode. The working electrode and a counter electrode made of a 2.2 cm × 2.2 cm lithium metal foil were opposed to each other through a glass filter (separator), and lithium metal was inserted as a reference electrode so as not to touch the working electrode and the counter electrode. These electrodes are placed in a three-electrode glass cell, and each of the working electrode, the counter electrode, and the reference electrode is connected to the terminal of the glass cell, and an electrolytic solution (in a solvent in which ethylene carbonate and γ-butyrolactone are mixed at a volume ratio of 1: 2). 25 mL of 1.5 M / L lithium tetrafluoroborate [LiBF ₄ ] was poured, and the separator and the electrode were sufficiently impregnated with the electrolyte, and then the glass container was sealed. The obtained glass cell was placed in a thermostatic bath at 25 ° C., and the potential of the working electrode when charged at a current density of 0.1 mA / cm ² was measured as the Li storage potential.

<Separator>
A roll of wound 30 μm thick cellulose long paper was prepared. One end in the axial direction of the scroll is immersed in a heated and melted polyethylene solution, and then taken out, and dried to form a polyethylene-containing region at one end in the axial direction of the scroll, that is, one end along the longitudinal direction of the long paper. did. Subsequently, the other end in the axial direction of the scroll is again immersed in the polyethylene solution, taken out, and then dried to contain polyethylene in the other end in the axial direction of the scroll, that is, the other end along the longitudinal direction of the long paper. By forming the region, a separator having polyethylene-containing regions at both ends along the longitudinal direction was manufactured. In this separator, the area of the polyethylene-containing region on each end side was 2% (total 4%) with respect to the total area.

<Preparation of liquid nonaqueous electrolyte>
A liquid nonaqueous electrolyte is prepared by dissolving 1.5 mol / L of lithium tetrafluoroborate (LiBF ₄ ) as an electrolyte in a mixed solvent (volume ratio 25:75) of ethylene carbonate (EC) and γ-butyrolactone (BL). (Nonaqueous electrolyte) was prepared.

<Assembly of secondary battery>
After connecting the terminals to the positive and negative electrode current collectors and laminating the positive electrode, the separator, the negative electrode, and the separator in this order, the laminate is connected to the polyethylene-containing region where the positive electrode and negative electrode terminals are along the longitudinal direction of the separator. I wound it up to make a right angle. Subsequently, the wound product was heated and pressed at 90 ° C. to produce a flat electrode group having dimensions of 70 × 100 mm and a thickness of 3.0 mm. At this time, the polyethylene-containing regions along the longitudinal direction of the separator were heat-sealed to each other at the overlapping portions. Next, a pack (bag-shaped exterior material) made of a laminate film having a thickness of 0.1 mm made of aluminum foil having a thickness of 40 μm with a polyethylene film laminated on both sides was prepared, and obtained in this bag-shaped exterior material. The obtained electrode group was housed in which the positive and negative terminals extended from the opening of the exterior material to the outside, and vacuum dried at 80 ° C. for 24 hours.

  Next, after storing the electrode group and injecting the liquid non-aqueous electrolyte into the bag-shaped exterior material, the opening of the bag-shaped exterior material is completely sealed by heat sealing, and has the structure shown in FIG. A nonaqueous electrolyte secondary battery having dimensions of 80 × 120 mm and a thickness of 3.0 mm was manufactured.

(Examples 2 to 7)
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the separator material, the type of heat-fusible resin, and the area of the heat-fusible resin-containing region were as shown in Table 1 below.

(Comparative Example 1)
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that a separator made of cellulose paper and having no heat-fusible resin-containing region was used.

(Comparative Example 2)
<Production of negative electrode>
As the negative electrode active material, graphite having an average particle size of 3 μm and a Li storage potential of 0.15 V (vs. Li / Li ⁺ ) was prepared. This negative electrode active material, acetylene black as a conductive material, and polyvinylidene fluoride (PVdF) having an average molecular weight of 4 × 10 ⁵ are mixed with N-methylpyrrolidone (NMP) at a weight ratio of 95: 2.5: 2.5. ) Added to the solution and mixed to prepare a slurry. The obtained slurry was applied to a copper foil (current collector) having a thickness of 10 μm, dried, and pressed to prepare a negative electrode having an electrode density of 1.5 g / cm ³ .

  A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the negative electrode and the separator shown in Table 1 below were used.

  Regarding the obtained secondary batteries of Examples 1 to 7 and Comparative Examples 1 and 2, the input density and the output density related to the short-circuit defective rate during manufacturing, the cycle characteristics, and the large current discharge characteristics described in detail below were measured. These results are shown in Table 1 below.

1) Short circuit defective rate during production After the electrode group was prepared by winding the separator used in each example and each comparative example between the electrodes made of aluminum foil, the tester was not impregnated with the electrolyte solution. The presence or absence of a short circuit was confirmed by examining the continuity between the electrodes. The short-circuit defect rate was calculated from the number of shorts with respect to the total number of electrode groups by inspecting 1000 electrode groups.

2) Cycle characteristics Each secondary battery was subjected to a charge / discharge cycle test at a 1C rate in a 45 ° C environment, the discharge capacity at the 1000th cycle was measured, and the discharge capacity maintenance rate relative to that at the initial cycle was calculated.

3) Input density and output density ・ Discharge pulse measurement (output)
In a 25 ° C. environment, constant current and constant voltage charging was performed at a 1 C rate, and the charged battery was discharged at 1 C up to a charge capacity ratio of 50%. Thereafter, pulse discharge was performed in units of 20A, 40A, 60A, and 20A in increments of 5 seconds. During each pulse, charging is performed to compensate for the amount of electricity discharged at 20 A so that the fluctuation of the charge capacity ratio is minimized, and the pulse current value is increased until the battery voltage becomes equal to or lower than the discharge cutoff potential during pulse discharge. The cycle was repeated.

・ Charge pulse measurement (input)
After the discharge pulse measurement was completed, a charge pulse was applied until the battery voltage became equal to or higher than the set charge potential, and a cycle for discharging to compensate the charge electricity amount at 20 A was repeated.

・ Input / output density In the current-voltage curve in which the battery voltage at the end of each pulse measurement is plotted against the pulse current, find the maximum current value until the cutoff voltage is reached, and multiply the current value by the cutoff voltage. Was calculated by dividing by the weight of the battery.

In addition, the area of the heat-sealable resin-containing region in Table 1 below is the total of both end portions along the longitudinal direction of the separator, and the area of each end portion is substantially the same area.

  As can be seen from Table 1, the secondary batteries of Examples 1 to 7 were used as secondary batteries in Comparative Example 1 having a paper separator made of cellulose in which no heat-fusible resin-containing region was formed at both ends along the longitudinal direction. It can be seen that the short-circuit defect rate is low and the cycle characteristics are excellent.

  In particular, in the secondary batteries of Examples 1 to 6 including the separator with the area of the heat-fusible resin-containing region of 4 to 50%, the area of the heat-fusible resin-containing region exceeds 50% (60%). Compared with the secondary battery of Example 7 provided with the separator of Example 7, it shows a large input density and output density, and it can be seen that it has excellent large current discharge characteristics.

On the other hand, even when a separator in which a heat-fusible resin-containing region is formed with an area of 20% at both ends along the longitudinal direction as in the secondary battery of Comparative Example 2, the Li occlusion potential is 0 as the negative electrode active material. When graphite [0.15 V (vs. Li / Li ⁺ )] less than .4 V (vs. Li ^/ Li ⁺ ) is used, a short circuit occurs in 150 cycles, and the input density and output density are also low, resulting in a large current. Discharge characteristics are inferior. This is because, as the negative electrode active material, the Li occlusion potential is as low as 0.15 V (vs. Li / Li ⁺ ), and since the negative electrode potential is low, some of the decomposition products generated at the interface between the positive electrode and the nonaqueous electrolyte are present on the negative electrode surface. This is because it is easy to deposit.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

Sectional drawing which shows the lithium ion secondary battery which is an example of the nonaqueous electrolyte battery which concerns on 1st Embodiment. The expanded sectional view which shows the A section of FIG. The top view which shows the separator of FIG. The partial notch perspective view which shows another square type flat battery which concerns on 1st Embodiment. The expanded sectional view of the B section of FIG. The disassembled perspective view of the battery pack which concerns on 2nd Embodiment. The block diagram which shows the electric circuit of the battery pack of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,11 ... Electrode group, 2 ... Exterior material, 3,15 ... Negative electrode, 4,16 ... Separator, 4a ... Heat-sealable resin containing area | region, 5,14 ... Positive electrode, 6,20 ... Negative electrode terminal, 7, 19 DESCRIPTION OF SYMBOLS ... Positive electrode terminal, 12 ... Bottomed rectangular cylinder, 13 ... Cover, 31 ... Single cell, 34 ... Printed wiring board, 35 ... Thermistor, 36 ... Protection circuit, 47 ... Storage container.

Claims (7)

An electrode group having an exterior material, a negative electrode containing a positive electrode, a negative electrode active material having a Li occlusion potential of 0.4 V (vs. Li / Li ⁺ ) or higher, and a separator, and is impregnated into at least the electrode group. A non-aqueous electrolyte,
The separator is made of at least one paper selected from cellulose and natural fiber pulp, is wound with the positive electrode and the negative electrode, or has a long shape, and is folded in the longitudinal direction. A non-aqueous electrolyte battery comprising: a heat-sealing resin-containing region at both ends along the line, wherein at least a part of the portions of the heat-sealing resin-containing region overlapping each other is heat-sealed.   The non-aqueous electrolyte battery according to claim 1, wherein the heat-sealing resin-containing region of the separator is 4% or more and 50% or less with respect to the total area of the separator.   The non-aqueous electrolyte battery according to claim 1, wherein the heat sealing resin includes polyethylene or polypropylene.   The non-aqueous electrolyte battery according to claim 1, wherein the negative electrode active material contains lithium titanium oxide.   The non-aqueous electrolyte battery according to claim 4, wherein the lithium titanium oxide has a spinel structure.   A battery pack comprising a plurality of the nonaqueous electrolyte batteries according to claim 1.   The battery pack according to claim 6, wherein the battery pack is for in-vehicle use.

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