JP2016058264A - Electrode group and nonaqueous electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode group which enables the materialization of a nonaqueous electrolyte battery superior in rate characteristic and cycle characteristic.SOLUTION: An electrode group 1 according to an embodiment comprises: a negative electrode 4; a positive electrode 3; and a separator 5. The negative electrode 4 includes: a negative electrode current collector 4a; and a negative electrode layer 4b. The negative electrode layer 4b includes a lithium titanium oxide. The positive electrode 3 includes: a positive electrode current collector 3a; and a positive electrode layer 3b. The separator 5 is disposed between the negative electrode layer 4b and the positive electrode layer 3b. The separator 5 includes at least one material having a high heat resistance. The separator 5 has a thickness of 3-9 μm. The negative electrode current collector 4a includes: a negative electrode coating part 4c with a negative electrode layer 4b supported on its surface; and a negative electrode uncoated part 4d which does not support the negative electrode layer 4b on the surface. The ratio of the area of the negative electrode uncoated part 4d to the area of the negative electrode coating part 4c is 0.05-0.07.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to an electrode group and a nonaqueous electrolyte battery.

  In recent years, non-aqueous electrolyte batteries that are charged and discharged by moving Li ions between a negative electrode and a positive electrode have been developed from the viewpoint of energy problems, environmental problems, and the like, such as electric vehicles (EV), hybrid vehicles (HEV), and It is expected as a large power storage device for stationary power generation systems such as solar power generation.

  Large non-aqueous electrolyte batteries are required to have not only high energy density but also excellent rapid charge / discharge performance and long-term reliability.

  In particular, a nonaqueous electrolyte battery excellent in rapid charge / discharge performance is not only capable of shortening the charging time, but also has an advantage that HEV can efficiently recover the regenerative energy of power.

  With the increase in size and output of non-aqueous electrolyte batteries such as the above-mentioned on-vehicle power supplies, the current value during charging and discharging increases, and heat generation cannot be ignored.

  The heat generation can be increased at the current collecting tab and the lead portion where the current density increases and the portion where the positive electrode and the negative electrode face each other.

  When the heat generated during charging / discharging is increased, the nonaqueous electrolyte is decomposed, and as a result, there is a problem that the deterioration of the battery material is accelerated.

  Therefore, there is a method of suppressing heat generation by reducing the ratio of the active material coating portion in the electrode for the nonaqueous electrolyte battery.

  Usually, an electrode for a non-aqueous electrolyte battery is formed by applying a slurry for an electrode on a current collector using a metal foil, leaving an uncoated part, that is, an exposed part of the metal foil, drying the coating film, and It can produce by forming an electrode layer by pressing.

  At this time, by reducing the application area of the electrode slurry, the electrode facing portion can be reduced and the current collecting tab portion can be widened. By spreading the current collecting tab portion, the current density during charging / discharging can be reduced, and as a result, heat generation can be suppressed.

  On the other hand, when the current collecting tab portion spreads, the coating area decreases according to the ratio. When the same exterior material is used, a decrease in the coating area causes a decrease in battery capacity. Even if the current value to be taken out is the same, the smaller the capacity, the larger the substantial load, that is, the C rate. When the C rate increases, the overvoltage increases and the output characteristics deteriorate.

  As described above, the output characteristics and cycle characteristics of the nonaqueous electrolyte battery depend on the ratio of the active material coated portion in the electrode and are in a trade-off relationship with each other.

JP 2014-594 A JP 2014-35935 A

  The problem to be solved by the present invention is to provide an electrode group capable of realizing a nonaqueous electrolyte battery excellent in rate characteristics and cycle characteristics, and such a nonaqueous electrolyte battery.

  According to a first embodiment, an electrode group is provided. The electrode group includes a negative electrode, a positive electrode, and a separator. The negative electrode includes a negative electrode current collector and a negative electrode layer formed on a part of the surface of the negative electrode current collector. The negative electrode layer includes lithium titanium oxide. The positive electrode includes a positive electrode current collector and a positive electrode layer formed on a part of the surface of the positive electrode current collector. The separator is disposed between the negative electrode layer and the positive electrode layer. The separator includes at least one selected from the group consisting of cellulose, polyimide, polyamideimide, polyethersulfone, polyetherketone, polybenzimidazole, wholly aromatic polyester, and aromatic polyamide. The separator has a thickness of 3 μm or more and 9 μm or less. The negative electrode current collector has a strip shape having a pair of long sides. The negative electrode current collector includes a negative electrode coated portion carrying a negative electrode layer on the surface and a negative electrode uncoated portion not carrying a negative electrode layer on the surface. The negative electrode coated portion and the negative electrode uncoated portion are adjacent to each other. The negative electrode uncoated portion includes one long side of the pair of long sides of the negative electrode current collector. The ratio of the area of the negative electrode uncoated part to the area of the negative electrode coated part is from 0.05 to 0.07. The positive electrode current collector includes a positive electrode coated portion carrying a positive electrode layer on the surface and a positive electrode uncoated portion not carrying a positive electrode layer on the surface. The ratio of the area of the positive electrode uncoated part to the area of the positive electrode coated part is 0.07 or more and 0.09 or less.

  According to the second embodiment, a nonaqueous electrolyte battery is provided. This nonaqueous electrolyte battery includes the electrode group according to the first embodiment and a nonaqueous electrolyte.

FIG. 1 is a partially exploded perspective view of an example electrode group according to the first embodiment. FIG. 2 is a partially cutaway development view of the positive electrode included in the electrode group shown in FIG. 1. FIG. 3 is a partially cutaway development view of the negative electrode included in the electrode group shown in FIG. 1. FIG. 4 is a plan view of the electrode group shown in FIG. FIG. 5 is a schematic perspective view of an example nonaqueous electrolyte battery according to the second embodiment. 6 is an exploded view of the nonaqueous electrolyte battery shown in FIG. FIG. 7 is a further exploded view of the nonaqueous electrolyte battery shown in FIG.

  Hereinafter, embodiments will be described 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 embodiment, and its shape, dimensions, ratio, etc. are different from the actual device, but these are the following explanations and known techniques. The design can be changed as appropriate.

(First embodiment)
According to a first embodiment, an electrode group is provided. The electrode group includes a negative electrode, a positive electrode, and a separator. The negative electrode includes a negative electrode current collector and a negative electrode layer formed on a part of the surface of the negative electrode current collector. The negative electrode layer includes lithium titanium oxide. The positive electrode includes a positive electrode current collector and a positive electrode layer formed on a part of the surface of the positive electrode current collector. The separator is disposed between the negative electrode layer and the positive electrode layer. The separator includes at least one selected from the group consisting of cellulose, polyimide, polyamideimide, polyethersulfone, polyetherketone, polybenzimidazole, wholly aromatic polyester, and aromatic polyamide. The separator has a thickness of 3 μm or more and 9 μm or less. The negative electrode current collector has a strip shape having a pair of long sides. The negative electrode current collector includes a negative electrode coated portion carrying a negative electrode layer on the surface and a negative electrode uncoated portion not carrying a negative electrode layer on the surface. The negative electrode coated portion and the negative electrode uncoated portion are adjacent to each other. The negative electrode uncoated portion includes one long side of the pair of long sides of the negative electrode current collector. The ratio of the area of the negative electrode uncoated part to the area of the negative electrode coated part is from 0.05 to 0.07. The positive electrode current collector includes a positive electrode coated portion carrying a positive electrode layer on the surface and a positive electrode uncoated portion not carrying a positive electrode layer on the surface. The ratio of the area of the positive electrode uncoated part to the area of the positive electrode coated part is 0.07 or more and 0.09 or less.

  First, when the electrode group according to the first embodiment is used in a non-aqueous electrolyte battery, since the ratio of the area of the negative electrode uncoated part to the area of the negative electrode coated part is 0.07 or less, the negative electrode uncoated The current density at the part increases. Further, since the ratio of the area of the positive electrode uncoated part to the area of the positive electrode coated part is 0.09 or less, when the electrode group according to the first embodiment is used in the nonaqueous electrolyte battery, the positive electrode uncoated The current density at the part increases. And in the electrode group which concerns on 1st Embodiment, the ratio with respect to the area of the negative electrode coating part of the area of a negative electrode uncoated part is 0.07 or less, and the area | region of a positive electrode coating part of the area of a positive electrode uncoated part Since the ratio with respect to an area is 0.09 or less, the area which a positive electrode and a negative electrode oppose can be enlarged more. Thereby, a big electric current can flow into a negative electrode uncoated part and a positive electrode uncoated part.

  As described above, when the electrode group according to the first embodiment is used in a non-aqueous electrolyte battery, a large current can flow in the negative electrode uncoated portion and the positive electrode uncoated portion with a small area. Can generate heat.

  For example, in an electrode group including a negative electrode using a carbon material as a negative electrode active material and a polyolefin as a separator, the negative electrode and the separator are deteriorated by heat generated during a charge / discharge cycle, and as a result, battery characteristics may be deteriorated.

  On the other hand, in the electrode group which concerns on embodiment, the negative electrode layer containing lithium titanium oxide and the separator containing the said material are excellent in heat resistance. In the electrode group according to the first embodiment, the ratio of the area of the negative electrode uncoated part to the area of the negative electrode coated part is 0.05 or more and the area of the positive electrode coated part of the positive electrode uncoated part is Thanks to the ratio being 0.07 or more, the generated heat can be prevented from becoming excessive. As a result, deterioration of the electrode group due to heat generated during the charge / discharge cycle can be reduced.

  Further, the separator having a thickness of 3 μm or more and 9 μm or less can quickly diffuse the heat generated locally in the electrode group throughout the electrode group. Thereby, temperature imbalance in the electrode group can be prevented, and as a result, deterioration of battery characteristics due to cycling can be further prevented.

  Thanks to these, the nonaqueous electrolyte battery including the electrode group according to the first embodiment can exhibit excellent cycle characteristics.

  And since the electrode group which concerns on 1st Embodiment can diffuse the heat | fever which generate | occur | produced in the charging / discharging cycle to the whole electrode group rapidly, even if an electric current value is large, it can prevent deterioration of an electrode group. . Moreover, the electrode group which concerns on 1st Embodiment can utilize the heat | fever which generate | occur | produced during the charging / discharging cycle, when using in a nonaqueous electrolyte battery. Specifically, when the temperature in the battery temporarily rises due to heat generation during charge and discharge, the diffusion of lithium ions in the electrolyte and the reaction at the electrode interface are promoted, and the rate characteristics can be improved. As a result, the nonaqueous electrolyte battery including the electrode group according to the first embodiment can exhibit excellent rate characteristics.

  That is, the electrode group according to the first embodiment can realize a nonaqueous electrolyte battery excellent in rate characteristics and cycle characteristics.

  Next, the electrode group according to the first embodiment will be described in more detail.

(1) Lithium titanium oxide The electrode group which concerns on 1st Embodiment contains lithium titanium oxide in the negative electrode layer of a negative electrode.

The lithium titanium oxide is, for example, a spinel that can be represented by the general formula Li _{4 + x} Ti ₅ O ₁₂ (where x can vary within a range of 0 ≦ x ≦ 3 depending on the state of charge). Type lithium titanate. Since spinel type lithium titanate has a stable crystal structure, a non-aqueous electrolyte battery having excellent life characteristics can be realized.

  In addition, since lithium titanium oxide has a higher lithium ion insertion and desorption potential than carbon, there are few side reactions when the battery is exposed to high temperatures, and resistance rise is small. Therefore, even if the battery becomes high temperature due to heat generation during charging / discharging, deterioration hardly occurs.

  Moreover, lithium titanium oxide has high insulation in a discharged state. Therefore, even if the negative electrode containing lithium titanium oxide should come into contact with the positive electrode under the influence of heat generation near the terminal, the contact part is immediately discharged and the short-circuit current is stopped. Safety can be shown.

  The lithium titanium oxide can be safely used in combination with a separator having a thickness of 3 μm or more and 9 μm or less. The reason is as follows. Lithium titanium oxide has a higher lithium ion insertion and desorption potential than carbon, and therefore, a negative electrode containing lithium titanium oxide as an active material does not deposit lithium dendrite on the surface even after repeated charge and discharge. Therefore, even when a negative electrode containing lithium titanium oxide as an active material is combined with a separator having a thickness of 3 μm or more and 9 μm or less, there is no possibility that lithium dendrite breaks through the separator. In addition, lithium titanium oxide has a very small volume change upon insertion and extraction of Li. Therefore, even when a negative electrode containing lithium titanium oxide as an active material is combined with a separator having a thickness of 3 μm or more and 9 μm or less, the separator is less likely to be broken by stress exerted on the separator from the negative electrode by repeated charge and discharge.

  On the other hand, in a negative electrode using, for example, carbon as the negative electrode active material, lithium dendrite can be deposited on the surface of the negative electrode by a charge / discharge cycle. When a negative electrode using carbon as a negative electrode active material is combined with a separator having a thickness of 3 μm or more and 9 μm or less, lithium dendrite that grows by repeated charge and discharge breaks through the separator, and a short circuit occurs between the negative electrode and the positive electrode There is a fear. In addition, carbon has a large volume change upon insertion and extraction of lithium. Therefore, in an electrode group in which an electrode using carbon as a negative electrode active material is combined with a separator having a thickness of 3 μm or more and 9 μm or less, a large stress is applied from the negative electrode to the separator every time charging and discharging are repeated. Can be destroyed. As described above, an electrode in which an electrode using carbon as a negative electrode active material is combined with a separator having a thickness of 3 μm to 9 μm has a safety problem.

(2) Separator The electrode group according to the first embodiment includes a separator. The separator is disposed between the negative electrode layer of the negative electrode and the positive electrode layer of the positive electrode.

  The material of the separator is at least one selected from the group consisting of cellulose, polyimide, polyamideimide, polyethersulfone, polyetherketone, polybenzimidazole, wholly aromatic polyester, and aromatic polyamide.

  These materials are materials having high heat resistance. The material having high heat resistance here refers to a resin material having a glass transition point of 200 ° C. or higher or a material having no glass transition point.

  Examples of resins having a glass transition point of 200 ° C. or higher are polyimide, polyamideimide, polyethersulfone, polyetherketone, polybenzimidazole, wholly aromatic polyester, and aromatic polyamide. On the other hand, an example of a material that does not include a glass transition point is cellulose.

  The separator may be formed from one of these materials, or may be formed from a combination of two or more of these materials.

  Since this separator includes a material having high heat resistance, even if heat is generated in the electrode group during charging / discharging, the separator can exist stably, and deterioration can be prevented. In addition, when this separator is used in combination with a negative electrode containing lithium titanium oxide, heat generation can be quickly and uniformly diffused into the electrode, so that the effect on the battery can be reduced if the separator does not deteriorate. it can.

  On the other hand, since the polyolefin separator has a low glass transition temperature and melting temperature of polyolefin, a part of the polyolefin separator may be dissolved when heat is generated near the terminal. As a result, the pores are blocked and the battery becomes high resistance. In addition, when the heat generation near the terminal is further high, there is a risk that the separator dissolves, causing contact between the positive electrode and the negative electrode, so-called internal short circuit, leading to abnormal heat generation of the battery.

  Examples of the structure of the separator include a porous film, a nonwoven fabric, and a layered state of particles, but any structure may be used.

  Large pores may occur in the nonwoven fabric structure. Large pores in the separator may cause contact between the positive electrode layer and the negative electrode layer. However, in the electrode group according to the first embodiment, since the negative electrode includes lithium titanate, as described above, even if the positive electrode layer and the negative electrode layer are in contact and short-circuited, abnormal heat generation is suppressed. Can use batteries safely.

  The thickness of the separator is 3 μm or more and 9 μm or less. If the thickness of the separator is less than 3 μm, a short circuit may occur due to irregularities on the surface of the negative electrode. On the other hand, when the thickness of the separator is larger than 9 μm, it becomes difficult to quickly and uniformly diffuse the heat generated during charging and discharging, and temperature unevenness tends to occur in the battery. Temperature unevenness in the battery can adversely affect rate characteristics.

  As described above, such a separator having a thickness of 3 μm or more and 9 μm or less cannot be used in a safe combination with a carbon negative electrode. On the other hand, as described above, the negative electrode including lithium titanium oxide has neither a problem of lithium dendrite precipitation nor a problem of stress applied to the separator from the negative electrode during charging / discharging, so the thickness is 3 μm or more and 9 μm or less. It can be used safely in combination with such a separator.

  Preferably, the thickness of the separator is not less than 5 μm and not more than 7 μm.

(3) Negative Electrode The negative electrode included in the electrode group according to the first embodiment includes a negative electrode current collector and a negative electrode layer. The negative electrode current collector has a strip shape having a pair of long sides. The negative electrode layer is formed on part of the surface of the negative electrode current collector. Therefore, the negative electrode current collector includes a negative electrode coated portion carrying a negative electrode layer on the surface and a negative electrode uncoated portion not carrying a negative electrode layer on the surface. Here, the negative electrode coated portion and the negative electrode uncoated portion are adjacent to each other. The negative electrode uncoated portion includes one long side of the pair of long sides of the negative electrode current collector.

  The ratio of the area of the negative electrode uncoated portion of the negative electrode current collector to the area of the negative electrode coated portion is from 0.05 to 0.07. Here, the area of the negative electrode coating portion refers to the area of the portion carrying the negative electrode layer on both surfaces of the negative electrode current collector. Similarly, the negative electrode uncoated portion refers to the area of the portion of the both surfaces of the negative electrode current collector that does not carry the negative electrode layer.

  When this ratio exceeds 0.07, the ratio of the negative electrode layer in the negative electrode becomes too low, and the capacity of the nonaqueous electrolyte battery including this negative electrode is reduced. The decrease in battery capacity increases the load on the electrode, and the output decreases. On the other hand, if this ratio is less than 0.05, the negative electrode uncoated portion becomes too small, and when this electrode group is used in a non-aqueous electrolyte battery, the current density in the negative electrode uncoated portion becomes too high and excessive. May generate excessive heat.

  The ratio of the area of the negative electrode uncoated part to the area of the negative electrode coated part is preferably 0.05 or more and 0.06 or less.

  Here, the distance from the long side included in the negative electrode uncoated portion to the negative electrode coated portion is referred to as the width of the negative electrode uncoated portion. The negative electrode layer may be formed such that the end face is formed in parallel to the long side of the negative electrode current collector, or the end face of the negative electrode layer may not be parallel to the long side of the negative electrode current collector.

  When the end face of the negative electrode layer is not parallel to the long side of the negative electrode current collector, the width of the negative electrode uncoated part is the minimum length of the distance from the long side included in the negative electrode uncoated part to the negative electrode uncoated part. Distance.

(4) Positive Electrode The positive electrode included in the electrode group according to the first embodiment includes a positive electrode current collector and a positive electrode layer. The positive electrode layer is formed on a part of the surface of the positive electrode current collector. Therefore, like the negative electrode current collector, the positive electrode current collector includes a positive electrode coated portion carrying a positive electrode layer on the surface and a positive electrode uncoated portion not carrying a positive electrode layer on the surface.

  The ratio of the area of the positive electrode uncoated part of the positive electrode current collector to the area of the positive electrode coated part is 0.07 or more and 0.09 or less.

  When this ratio exceeds 0.09, the ratio of the positive electrode layer in the positive electrode becomes too small, and the capacity of the nonaqueous electrolyte battery including this positive electrode is reduced. The decrease in battery capacity increases the load on the electrode, and the output decreases. On the other hand, when this ratio is less than 0.07, the positive electrode uncoated portion becomes too small, and when this electrode group is used in a non-aqueous electrolyte battery, the current density in the positive electrode uncoated portion becomes too high and excessive. May generate excessive heat.

  The ratio of the area of the positive electrode uncoated part to the area of the positive electrode coated part is preferably 0.07 or more and 0.08 or less.

  The positive electrode current collector can be, for example, a strip having a pair of long sides. The positive electrode layer can be formed, for example, so that the positive electrode uncoated portion includes one long side of the positive electrode current collector. The positive electrode layer may be formed so that the end face is formed in parallel to the long side of the positive electrode current collector, or the end face of the positive electrode layer may not be parallel to the long side of the positive electrode current collector.

  By forming the positive electrode layer in this way, the positive electrode coated portion and the positive electrode uncoated portion can be adjacent to each other. Here, the distance from the long side included in the positive electrode uncoated part to the positive electrode coated part is referred to as the width of the positive electrode uncoated part.

  When the end face of the positive electrode layer is not parallel to the long side of the positive electrode current collector, the width of the positive electrode uncoated part is the minimum length of the distance from the long side included in the positive electrode uncoated part to the positive electrode uncoated part. Distance.

(5) Relationship between negative electrode and positive electrode The area of the negative electrode coating part is preferably larger than the area of the positive electrode coating part.

  At the coating end of the electrode layer, current tends to concentrate and heat generation tends to occur. In the electrode group in which the area of the negative electrode coating part is larger than the area of the positive electrode coating part, the negative electrode layer can be opposed to the coating end of the positive electrode layer, so that the current easily flows to the negative electrode. The influence of current concentration in the can be reduced.

  On the other hand, since the lithium titanium oxide contained in the negative electrode layer has excellent rate characteristics, heat generated during charging and discharging can be quickly diffused throughout the battery. Therefore, the negative electrode is less affected by the current concentration at the coating end of the electrode layer than the positive electrode. Therefore, the positive electrode layer may not face the coating end of the negative electrode layer.

  That is, in the electrode group according to the first embodiment, the negative electrode coating portion having a larger area than the positive electrode coating portion can further suppress the bias and deterioration of heat generation during charging and discharging.

(6) Structure of electrode group The electrode group according to the first embodiment may be, for example, a wound electrode group. The wound electrode group may have a wound structure in which a positive electrode and a negative electrode are stacked with a separator interposed therebetween, and the stacked body thus obtained is wound in a spiral shape.

  In the electrode group according to the first embodiment, a part of the negative electrode uncoated part including one long side of the negative electrode current collector and one of the positive electrode uncoated part including one long side of the positive electrode current collector are provided. Can protrude from the electrode group in opposite directions. Thereby, since the negative electrode uncoated part and the positive electrode uncoated part are exposed, it becomes easy to use these as a negative electrode tab and a positive electrode tab, respectively.

  In this case, it is preferable that the ratio of the length of the portion of the negative electrode uncoated portion protruding from the electrode group to the length of the electrode group is 0.03 or more and less than 0.05. Such an electrode group in the electrode group according to the first embodiment, when used in a non-aqueous electrolyte battery, sufficiently secures the width of a terminal connected to a portion protruding from the electrode group in the negative electrode uncoated portion. Thus, an increase in current density can be suppressed, and as a result, excessive heat generation can be further suppressed. On the other hand, when such an electrode group is used in a non-aqueous electrolyte battery, the relative area of the positive electrode layer and the negative electrode layer in the electrode group can be sufficiently secured, and sufficient capacity can be secured. By securing a sufficient capacity, it is possible to suppress a load on the electrode group, and hence a decrease in output.

(7) Porosity of separator The porosity of the separator included in the electrode group according to the first embodiment is preferably 50% or more and 80% or less. When the porosity is 50% or more, heat generated during charging / discharging can be quickly diffused into the cell. As a result, it is possible to prevent imbalance in the temperature during discharge. Thereby, in an electrode group, it can prevent that an overvoltage arises locally or a high temperature location arises locally. As a result, it is possible to prevent the cycle characteristics from being degraded and the rate characteristics from being degraded. When the porosity is 80% or less, sufficient insulation can be provided between the positive electrode and the negative electrode. Thereby, the short circuit between a positive electrode and a negative electrode can be suppressed more fully. As a result, the movement of Li ions during discharge can be performed sufficiently, and the rate characteristics can be prevented from deteriorating. Furthermore, since an increase in side reaction due to KARAKU can be prevented, it is possible to prevent a decrease in cycle characteristics. A more preferable range of the porosity of the separator is 60% or more and 75% or less.

  Next, examples of each material that can be used in the electrode group according to the first embodiment will be described in detail.

(1) Negative electrode A negative electrode layer can contain a negative electrode active material and a electrically conductive agent and a binder as needed.

  Lithium titanium oxide is contained in the negative electrode active material.

The negative electrode active material preferably has an average primary particle size of 1 μm or less and a specific surface area of 5 m ² / g or more and 50 m ² / g or less by the BET method by N ₂ adsorption. The negative electrode active material having such an average particle diameter and specific surface area can increase the utilization rate, and can take out a substantially high capacity. Incidentally, BET specific surface area by N ₂ gas adsorption, for example, using a Micromeritics Tex ASPA-2010 of Shimadzu Corporation, the adsorbed gas can be measured using N _2.

  The conductive agent plays a role of assisting electrical conductivity between the active materials and forming a reaction field of the supported catalyst. Therefore, high electrical conductivity is required for the conductive agent. As the conductive agent, for example, conductive particles can be used. The conductive particles are not particularly limited, but are selected from the group consisting of graphites such as natural graphite and artificial graphite, carbon blacks such as acetylene black and ketjen black, and vapor grown carbon fibers such as carbon nanotubes and carbon nanofibers. At least one carbon material particle is preferred. On the other hand, diamond-like carbon, glassy carbon, conductive polymer, and the like are not preferable because their electrical conductivity is lower than that of conductive particles and the cost is high.

  Although the particle diameter of electroconductive particle is not specifically limited, It is preferable that an average primary particle diameter is 0.01 micrometer or more and 5 micrometers or less. When the particle diameter of the conductive particles is within the above range, the surface of the conductive particles can be supported in the form of particles by a metal or an alloy. By this carrying, the above effect can be sufficiently exhibited. The average primary particle size is measured by the following method. The diameter of the conductive particles is obtained by TEM observation, and an average value of an arbitrary number is set as an average primary particle diameter.

  A binder is mix | blended in order to bind an active material and an electrical power collector. Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluorine-based rubber, and styrene-butadiene rubber.

  For the negative electrode current collector, for example, a metal foil or an alloy foil can be used. The thickness of the current collector is desirably 20 μm or less, more preferably 15 μm or less.

  Examples of the metal foil include copper foil and aluminum foil. In the case of an aluminum foil, it is preferable to have a purity of 99% by weight or more.

  Examples of the alloy foil include stainless steel foil and aluminum alloy foil. The aluminum alloy foil is preferably an alloy containing elements such as magnesium, zinc, and silicon. Transition metals such as iron, copper, nickel and chromium contained as alloy components are preferably 1% by weight or less.

  For example, the negative electrode is prepared by adding a conductive agent and a binder to a powdered negative electrode active material, suspending them in a suitable solvent, applying the suspension (slurry) to a current collector, drying, and pressing. It can be produced by forming a strip electrode. As described above, slurry application is performed such that the negative electrode coated portion and the negative electrode uncoated portion are formed on the negative electrode current collector.

  When preparing the slurry for preparing a negative electrode, the negative electrode active material, the conductive agent, and the binder are 70% by weight to 96% by weight, 2% by weight to 28% by weight, and 2% by weight to 28% by weight, respectively. It is preferable to mix | blend in a ratio.

  When the content of the conductive agent is 2% by weight or more, the current collecting performance of the negative electrode layer can be improved. Further, when the content of the binder is 2% by weight or more, the binding property between the negative electrode layer and the current collector can be sufficiently obtained. Therefore, according to the above formulation, cycle characteristics can be further improved. On the other hand, from the viewpoint of increasing the capacity, the conductive agent and the binder are each preferably 28% by weight or less.

(2) Separator The material of the separator is as described above.

(3) Positive electrode The positive electrode layer can contain a positive electrode active material. The positive electrode layer can further contain a conductive agent and a binder as necessary.

Examples of the positive electrode active material include various oxides and sulfides. For example, manganese dioxide (MnO ₂ ), iron oxide, copper oxide, nickel oxide, lithium manganese composite oxide (eg, LixMn 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 (for example, Li _x Ni _{1 -yz} Co _y M _z O ₂ (M is at least one selected from the group consisting of Al, Cr and Fe) And 0 ≦ y ≦ 0.5 and 0 ≦ z ≦ 0.1)), lithium manganese cobalt composite oxide (for example, Li _x Mn _1-yz Co _y M _z O ₂ (M is At least one element selected from the group consisting of Al, Cr and Fe, and 0 ≦ y ≦ 0.5 and 0 ≦ z ≦ 0.1)), a lithium manganese nickel composite compound (for example, L _{x Mn 1/2 Ni 1/2 O 2)} , spinel type lithium-manganese-nickel composite oxide (e.g., _{Li x Mn 2-y Ni y} O 4), lithium phosphates having an olivine structure (e.g., Li _x FePO ₄ and _{Li x Fe 1-y Mn y} PO 4, Li x CoPO 4), iron sulfate (e.g. _{Fe 2 (SO 4) 3)} , vanadium oxide (e.g. V ₂ O _5), and the like.

  Other examples of the positive electrode active material include conductive polymer materials such as polyaniline and polypyrrole, disulfide polymer materials, organic materials such as sulfur (S) and carbon fluoride, and inorganic materials.

  In addition, about x, y, and z for which there is no description of a preferable range above, it is preferable that it is the range of 0 or more and 1 or less.

  The type of the positive electrode active material can be one type or two or more types.

  The conductive agent plays a role of assisting electrical conductivity between the active materials and forming a reaction field of the supported catalyst. Examples of the conductive agent include carbon black, graphite (graphite), graphene, fullerenes, coke and the like. Among these, carbon black and graphite are preferable, and examples of carbon black include acetylene black, ketjen black, and furnace black.

  A binder is mix | blended in order to bind an active material and an electrical power collector. Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), polyacrylic acid, and fluorine rubber.

  The positive electrode current collector is preferably formed from an aluminum foil or an aluminum alloy foil. The thickness of the current collector is preferably 20 μm or less, more preferably 15 μm or less.

  The average crystal grain size of the aluminum foil and the aluminum alloy foil is preferably 50 μm or less. More preferably, it is 30 μm or less. More preferably, it is 5 μm or less. When the average crystal grain size is 50 μm or less, the strength of the aluminum foil or aluminum alloy foil can be drastically increased, the positive electrode can be densified with a high press pressure, and the battery capacity is increased. Can be made.

  The purity of the aluminum foil is preferably 99% by weight 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% by weight or less.

  For the positive electrode, for example, a conductive agent and a binder are added to the positive electrode active material, these are suspended in a suitable solvent, and the suspension is applied to a current collector such as an aluminum foil, dried and pressed to form a belt-like shape. It is produced by making an electrode. As described above, slurry application is performed so that the positive electrode coated portion and the positive electrode uncoated portion are formed on the positive electrode current collector.

  When preparing the positive electrode preparation slurry, the mixing ratio of the positive electrode active material, the conductive agent and the binder is 80 to 95% by weight of the positive electrode active material, 3 to 20% by weight of the conductive agent, and 2 to 7% by weight of the binder. It is preferable to make it into a range.

  Next, an example of the electrode group according to the first embodiment will be described in more detail with reference to the drawings.

FIG. 1 is a partially exploded perspective view of an example electrode group according to the first embodiment. FIG. 2 is a partially cutaway development view of the positive electrode included in the electrode group shown in FIG. 1. FIG. 3 is a partially cutaway development view of the negative electrode included in the electrode group shown in FIG. 1. FIG. 4 is a plan view of the electrode group shown in FIG. In FIG. 2, the positive electrode layer 3b is not shown at one end portion of the positive electrode 3 shown on the right side of the drawing. Similarly, in FIG. 3, the negative electrode layer 4b is not shown at one end of the negative electrode 4 shown on the right side of the drawing. Further, “TD” in the direction TD _C and the direction TD _A shown in FIGS. 2 and 3 is an abbreviation of “transverse direction” and corresponds to the winding axis direction TD of the electrode group 1 shown in FIGS. doing. On the other hand, “MD” in the direction MD _C and the direction MD _A shown in FIGS. 2 and 3 is an abbreviation of “machine direction”, which is a direction perpendicular to the direction TD _C and the direction TD _A , respectively.

  A flat electrode group 1 shown in FIG. 1 includes a sheet-like positive electrode 3, a sheet-like negative electrode 4, and two sheet-like separators 5.

As shown in FIG. 2, the positive electrode 3 has a pair of long sides 3a _L having a length L3 extending in the direction MD _C and a pair of short sides 3a _W having a length W3 extending in the direction TD _C. have.

  The positive electrode 3 includes a positive electrode current collector 3a and a positive electrode layer 3b formed on a part of the surface of the positive electrode current collector 3a. Although not shown in FIG. 2, the positive electrode current collector 3a has the positive electrode layer 3b formed on both surfaces in the same manner.

The positive electrode current collector 3a includes a positive electrode coated portion 3c including one long side 3a _L of the positive electrode current collector 3a and a positive electrode uncoated portion 3d including the other long side 3a _L of the positive electrode current collector 3a. Contains.

The positive electrode coating part 3c carries the positive electrode layer 3b on the surface. On the other hand, the positive electrode uncoated portion 3d does not carry a positive electrode layer. The Seikyokunuriko portion 3c and the positive electrode uncoated portion 3d, are adjacent to each other in the direction TD _C.

In the positive electrode coating portion 3c and the positive electrode layer 3b carried thereon, the length in the direction MD _C is L3, and the length in the direction TD _C is W3c. Therefore, the area of the positive electrode coating portion 3c is the product of the length L3 and the length W3c.

In the positive electrode uncoated portion 3d, the length in the direction MD _C is L3, and the length in the direction TD _C is W3d. Therefore, the area of the positive electrode uncoated portion 3d is the product of the length L3 and the length W3d.

Here, the width a is length W3d positive electrode uncoated portion 3d in the direction TD _C is from long side 3a _L of the positive electrode current collector 3a included in the positive electrode uncoated portion 3d to the end face 3b _e of the positive electrode layer 3b the distance, i.e. the difference between the length W3c length W3 and the positive electrode coated portion 3c of the positive electrode 3 in the direction TD _C.

Negative electrode 4, as shown in FIG. 3, strip-shaped planar shape having a pair of long sides 4a _L length L4 extending in the direction MD _A, and a pair of short sides 4a _W length W4 extending in a direction TD _A have.

  The negative electrode 4 includes a negative electrode current collector 4a and a negative electrode layer 4b formed on a part of the surface of the negative electrode current collector 4a. Although not shown in FIG. 3, the negative electrode current collector 4a has the negative electrode layer 4b formed in the same manner on both sides.

The negative electrode current collector 4a includes a negative electrode coated portion 4c including one long side 4a _L of the negative electrode current collector 4a and a negative electrode uncoated portion 4d including the other long side 4a _L of the negative electrode current collector 4a. Contains.

The negative electrode coating part 4c carries the negative electrode layer 4b on the surface. On the other hand, the negative electrode uncoated portion 4d does not carry a negative electrode layer. The Fukyokunuriko portion 4c and the negative electrode uncoated portion 4d, are adjacent to each other in the direction TD _A.

Fukyokunuriko section 4c and the negative electrode layer 4b carried thereon is the length direction MD _A is L4, the length direction TD _A is W4c. Therefore, the area of the negative electrode coating part 4c is the product of the length L4 and the length W4c.

Negative electrode uncoated portion 4d is a length in the direction MD _A is L4, the length direction TD _A is W4D. Therefore, the area of the negative electrode uncoated portion 4d is the product of the length L4 and the length W4d.

The length W4d the width of the negative electrode uncoated portion 4d in the direction TD _A is from the long sides 4a _L of the negative electrode current collector 4a included in the negative electrode uncoated portion 4d to the end face 4b _e of the negative electrode layer 4b the distance, i.e. the difference between the length W4c negative electrode 4 length W4 and the negative electrode coating portion 4c in the direction TD _a.

  The positive electrode 3 and the negative electrode 4 and the separator 5 are laminated in the order of one separator 5, the positive electrode 3, another separator 5 and the negative electrode 4, with the negative electrode 4 facing inward, and FIG. It is wound around a winding axis extending in the winding axis direction TD shown.

At the time of lamination, the direction MD _C of the pair of long sides 3a _L of the positive electrode 3 and the direction MD _A of the pair of long sides 4a _L of the negative electrode 4 are aligned, and the direction TD _C of the pair of short sides 3a _W of the positive electrode 3 It is combined and direction TD _a pair of short sides 4a _W of the negative electrode 4. One separator 5 is laminated so as to cover a part of the positive electrode uncoated portion 3d. Similarly, the other separator 5 is laminated so as to cover a part of the negative electrode uncoated portion 4d. Thereby, the short circuit between the positive electrode 3 and the negative electrode 4 is prevented.

As shown in FIGS. 1 and 4, from the electrode group 1, a part 3d _p of the positive electrode uncoated part 3d and a part 4d _{p of the} negative electrode uncoated part 4d protrude in opposite directions. . The protruding portion 3d _p of the positive electrode uncoated portion 3d is a portion where the separator 5 is not covered. The protruding portion 4d _p of the negative electrode uncoated portion 4d is a portion where the separator 5 is not covered.

  The electrode group 1 shown in FIGS. 1 to 4 can be obtained by pressing the laminated body wound as described above into a flat shape.

  In the electrode group 1 shown in FIGS. 1 to 4, the ratio of the area L4 × W4d of the negative electrode uncoated portion 4d to the area L4 × W4c of the negative electrode coated portion 4c is 0.05 or more and 0.07 or less. The ratio of the area L3 × W3d of the positive electrode uncoated part 3d to the area L3 × W3c of the positive electrode coated part 3c is 0.07 or more and 0.09 or less.

As shown in FIG. 4, the length of the projecting portion 3d _p of the positive electrode uncoated portion 3d in the winding axis direction TD of the electrode group 1 is W3d _p. The length of the projecting portion 4d _p of the negative electrode uncoated portion 4d in the winding axis direction TD of the electrode group 1 is W4D _p. The length of the electrode group 1 in the winding axis direction TD is W1. The ratio of the length W3d _p and length W4D _p to the length W1 is less than 0.03 or more 0.05.

[Measuring method]
A method for measuring each dimension of the electrode group will be described below.

  First, an electrode group to be measured is prepared. The electrode group provided in the nonaqueous electrolyte battery is prepared by the following procedure.

  First, the nonaqueous electrolyte battery is disassembled, for example, by cutting the exterior material. The state of charge when disassembling the battery may be any. However, in consideration of safety, it is desirable to carry out the charging state as low as possible.

  The exterior material is cut at a location where the electrode group inserted therein is not damaged. At this time, the terminal and the lead connected to the terminal may be cut.

Next, an electrode group is taken out from the disassembled nonaqueous electrolyte battery.
Subsequently, the dimensions of the electrode group are measured from the extracted electrode group. In the case of the wound electrode group, the dimension in the winding axis direction and the dimension in the direction orthogonal to the winding axis direction are measured.

  The length can be measured using a known measuring method such as a ruler, caliper, measure, or laser displacement meter. In addition, when using a caliper, it is necessary to insulate the part which contacts the both ends of the charged battery.

In the case of the wound electrode group, subsequently, a part 3d _{p of} the positive electrode uncoated part 3d exposed by protruding from the electrode group, and a part 4d _{p of} the negative electrode uncoated part 4d exposed by protruding from the electrode group, Are measured in the winding axis direction. Measurement should be done avoiding the lead connection. This measurement can be performed using a known measurement method such as a ruler, caliper, or measure.

  Subsequently, the electrode group is disassembled into a positive electrode, a negative electrode, and a separator. In the case of a wound electrode group, the electrode group is developed in a direction opposite to that of winding so as not to cut the electrode, and then disassembled into a positive electrode, a negative electrode, and a separator.

  After disassembly, the length of the long side of the positive electrode and the length of the long side of the negative electrode are measured. The measurement is performed using a measure or the like by spreading the disassembled positive electrode and negative electrode in one direction.

  Subsequently, the dimensions of the positive electrode coated portion and the positive electrode uncoated portion of the positive electrode current collector and the negative electrode coated portion and the negative electrode uncoated portion of the negative electrode current collector are measured.

  For the positive electrode in which the width of the positive electrode uncoated portion is substantially constant or the negative electrode in which the width of the negative electrode uncoated portion is substantially constant, measurement is performed according to the following procedure. In the following description, the positive electrode and the negative electrode are collectively referred to as an electrode, the positive electrode coating portion and the negative electrode coating portion are collectively referred to as an electrode coating portion, and the positive electrode uncoated portion and the negative electrode uncoated portion are collectively referred to as an electrode. It is called an electrode uncoated part.

  First, each of the electrodes is cut along a direction perpendicular to the direction of the long side to produce several measurement samples having a size that can be easily measured.

  The measurement sample may be produced from any location on the electrode. It is desirable to prepare a plurality of measurement samples.

  Further, the length of the electrode to be cut off in the long side direction may be any, but it is preferably within 30 cm for ease of measurement.

  In the produced measurement sample, the lengths of the electrode coated part and the electrode uncoated part in the direction perpendicular to the long side direction of the electrode are measured. The measurement can be performed using a known measurement method such as a ruler, caliper, or measure. The measurement of the lengths of the electrode coated part and the electrode uncoated part in the direction perpendicular to the long side direction of the electrode may be performed at an arbitrary position of the measurement sample.

  The average length of the electrode coating part in the direction perpendicular to the long side direction of the electrode is defined as the length of the electrode coating part. Similarly, the average of the length of the electrode uncoated part in the direction perpendicular to the long side direction of the electrode is defined as the length of the electrode uncoated part.

  The area of the electrode coating portion can be calculated by multiplying the length of the electrode coating portion thus calculated by the length of the long side of the electrode. Similarly, the area of the electrode uncoated portion can be calculated by multiplying the length of the long side of the electrode by the length of the electrode uncoated portion calculated as described above.

  On the other hand, about the positive electrode where the width | variety of a positive electrode uncoated part is not constant or the negative electrode where the width | variety of a negative electrode uncoated part is not constant, it measures in the following procedures. In the following description, the positive electrode and the negative electrode are collectively referred to as an electrode, the positive electrode coating portion and the negative electrode coating portion are collectively referred to as an electrode coating portion, and the positive electrode uncoated portion and the negative electrode uncoated portion are collectively referred to as an electrode. It is called an electrode uncoated part.

  In the electrode coating portion of the electrode spread in one direction, the width of the portion having the largest dimension in the direction perpendicular to the long side direction of the electrode and the smallest width are measured. Similarly, in the electrode coating portion of the electrode expanded in one direction, the width of the portion having the largest dimension in the direction perpendicular to the long side direction of the electrode and the smallest width are measured.

  Here, the smallest width of the electrode coating portion is defined as the width of the electrode coating portion. Similarly, the smallest width of the electrode uncoated portion is defined as the width of the electrode uncoated portion.

  The width of the portion with the largest dimension in the direction perpendicular to the long side direction of the electrode of the electrode uncoated portion measured as described above is defined as WM, and the width in the direction perpendicular to the long side direction of the electrode of the electrode uncoated portion is measured. When the width Wm of the portion having the smallest dimension is set to L and the length in the long side direction of the electrode is set to L, the area S of the electrode uncoated portion can be calculated by the following formula.

S = (WM + Wm) × L ÷ 2
According to the first embodiment described above, an electrode group is provided. This electrode group includes a negative electrode and a separator excellent in heat resistance, and includes a positive electrode layer and a negative electrode layer so that heat is easily generated but excessive heat generation can be suppressed. The negative electrode contains lithium titanate, and the separator has a thickness of 3 μm to 9 μm. Thanks to this, when this electrode group is used in a non-aqueous electrolyte battery, it is possible to prevent the battery characteristics from being deteriorated, and furthermore, heat can be used effectively. Therefore, the electrode group according to the first embodiment can realize a nonaqueous electrolyte battery excellent in rate characteristics and cycle characteristics.

(Second Embodiment)
According to the second embodiment, a nonaqueous electrolyte battery is provided. This nonaqueous electrolyte battery includes the electrode group according to the first embodiment and a nonaqueous electrolyte.

  In the nonaqueous electrolyte battery according to the second embodiment, the nonaqueous electrolyte can be impregnated and held in the electrode group.

  Hereinafter, the nonaqueous electrolyte battery according to the second embodiment will be described in detail.

  The nonaqueous electrolyte battery according to the second embodiment can further include a container. The container can accommodate the electrode group according to the first embodiment and the nonaqueous electrolyte.

  The nonaqueous electrolyte battery according to the second embodiment can further include a positive electrode lead and a negative electrode lead. The positive electrode lead can be electrically connected to the positive electrode uncoated portion of the electrode group. Thereby, the positive electrode lead can serve as a conductor for electrons to move between the positive electrode and the external terminal. Similarly, the negative electrode lead can be electrically connected to the negative electrode uncoated portion of the electrode group. Thereby, the negative electrode lead can act as a conductor for electrons to move between the negative electrode and the external terminal.

  The nonaqueous electrolyte battery according to the second embodiment can further include a positive electrode terminal and a negative electrode terminal. The positive electrode terminal is electrically connected to the positive electrode directly or via a positive electrode lead. Similarly, the negative electrode terminal is electrically connected to the negative electrode directly or via a negative electrode lead. Moreover, the positive electrode terminal and the negative electrode terminal are partly located outside the container. Therefore, it is possible to supply power from the nonaqueous electrolyte battery to the external electronic device or input power from the power generation element to the nonaqueous electrolyte battery via the positive electrode terminal and the negative electrode terminal.

  The nonaqueous electrolyte battery according to the second embodiment preferably has a rated capacity of 10 Ah or more and less than 50 Ah. When the rated capacity is less than 50 Ah, heat generation during charging / discharging can be further suppressed, and further deterioration due to heat can be further suppressed. In addition, since the rated capacity is less than 50 Ah, heat generation during charging / discharging can be uniformly diffused, thereby preventing non-uniformity in resistance during discharging, and thus progress of charging / discharging. Can be prevented from occurring. As a result, the nonaqueous electrolyte battery according to the second embodiment having a rated capacity of less than 50 Ah can prevent overvoltage during charging and discharging, and can exhibit excellent rate characteristics. On the other hand, when the rated capacity is 10 Ah or more, a resistance reduction effect can be sufficiently expected. The nonaqueous electrolyte battery according to the second embodiment more preferably has a rated capacity of 20 Ah or more and less than 45 Ah.

  Next, the nonaqueous electrolyte, the positive electrode lead, the negative electrode lead, the container, the positive electrode terminal, and the negative electrode terminal will be described in more detail.

(1) Nonaqueous electrolyte The nonaqueous electrolyte can contain a nonaqueous solvent and an electrolyte salt dissolved in the nonaqueous solvent. Further, the non-aqueous solvent may contain a polymer.

Examples of the electrolyte salt include LiPF ₆ , LiBF ₄ , Li (CF ₃ SO ₂ ) ₂ N (bistrifluoromethanesulfonylamide lithium; commonly known as LiTFSI), LiCF ₃ SO ₃ (commonly known as LiTFS), and Li (C ₂ F ₅ SO _{2) 2} N (bis pentafluoroethanesulfonyl amide lithium; called _{LiBETI), LiClO 4, LiAsF 6} , LiSbF 6, bisoxalato Lato lithium borate _{(LiB (C 2 O 4)} 2 ( known as LiBOB)), difluoro (oxalato) Lithium borate (LiF ₂ BC ₂ O ₄ ), difluoro (trifluoro-2-oxide-2-trifluoro-methylpropionate (2-)-0,0) lithium borate (LiBF ₂ (OCOOC (CF ₃ ) ₂₎ (aka LiBF ₂ (HHIB))), lithium difluorophosphate (LiPO _{2 2)} lithium salts, and the like.

  These electrolyte salts may be used alone or in combination of two or more.

In particular, LiPF ₆ , LiBF ₄ , lithium bisoxalatoborate (LiB (C ₂ O ₄ ) ₂ (common name LiBOB)), lithium difluoro (oxalato) borate (LiF ₂ BC ₂ O ₄ ), difluoro (trifluoro-2 -Oxido-2-trifluoro-methylpropionate (2-)-0,0) lithium borate (LiBF ₂ (OCOOC (CF ₃ ) ₂ ) (commonly known as LiBF ₂ (HHIB))), lithium difluorophosphate (LiPO ₂ F ₂ ) is preferred.

  The electrolyte salt concentration is preferably in the range of 0.5M to 3.0M. Thereby, the performance when a high load current is passed can be improved.

  The non-aqueous solvent is not particularly limited, but propylene carbonate (PC), ethylene carbonate (EC), 1,2-dimethoxyethane (DME), γ-butyrolactone (GBL), tetrahydrofuran (THF), 2 -Methyltetrahydrofuran (2-MeHF), 1,3-dioxolane, sulfolane, acetonitrile (AN), diethyl carbonate (DEC), dimethyl carbonate (DMC), methyl ethyl carbonate (MEC), dipropyl carbonate (DPC), etc. It is done.

  These solvents may be used alone or in combination of two or more.

Further, when two or more kinds of solvents are combined, it is preferable to select from all solvents having a dielectric constant of 20 or more.

  An additive may be added to the non-aqueous electrolyte. Although it does not specifically limit as an additive, Vinylene carbonate (VC), fluoro vinylene carbonate, methyl vinylene carbonate, fluoromethyl vinylene carbonate, ethyl vinylene carbonate, propyl vinylene carbonate, butyl vinylene carbonate, dimethyl vinylene carbonate, diethyl Examples include vinylene carbonate, dipropyl vinylene carbonate, vinylene acetate (VA), vinylene butyrate, vinylene hexanate, vinylene crotonate, catechol carbonate, propane sultone, and butane sultone.

One kind or two or more kinds of additives can be used.

(2) Positive electrode lead and negative electrode lead The positive electrode lead is, for example, aluminum or an aluminum alloy containing at least one element selected from Mg, Ti, Zn, Ni, Cr, Mn, Fe, Cu, or Si. Preferably it is formed from. In order to reduce the contact resistance with the positive electrode current collector, the positive electrode lead terminal is preferably formed of the same material as the positive electrode current collector.

  The negative electrode lead can be formed from, for example, aluminum or an aluminum alloy containing at least one element selected from Mg, Ti, Zn, Mn, Fe, Cu, or Si. In order to reduce the contact resistance with the negative electrode current collector, the negative electrode lead is preferably formed of the same material as the negative electrode current collector. The negative electrode lead is preferably formed with the same width as the negative electrode uncoated portion.

  The positive electrode lead and the negative electrode lead can be omitted.

(3) Container As the container, for example, a metal container or a resin container can be used.

  For example, a metal container having a thickness of 3 mm or less can be used. More preferably, the metal container has a thickness of 0.5 mm or less.

  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.

  When transition metals such as iron, copper, nickel and chromium are contained in the alloy, the amount is preferably 100 ppm or less.

  As the resin container, for example, a resin container made of polyolefin resin, polyvinyl chloride resin, polystyrene resin, acrylic resin, phenol resin, polyphenylene resin, fluorine resin, or the like can be used.

  Alternatively, a container made of a laminate film in which a metal foil is sandwiched between two resin layers can be used as the container.

  The shape of the container, that is, the battery shape can be selected according to the application of the battery. For example, examples of the battery shape include a flat type (thin type), a square type, a cylindrical type, a coin type, and a button type. In addition, examples of the use of the battery include a small use mounted on a portable electronic device and the like, and a large use mounted on a two-wheel to four-wheel automobile, etc., and the nonaqueous electrolyte battery according to the second embodiment. Can be applied to any application.

(4) Positive electrode terminal and negative electrode terminal A positive electrode terminal can be formed from the material similar to a positive electrode electrical power collector or a positive electrode lead, for example. The negative electrode terminal can be formed from the same material as the negative electrode current collector or the negative electrode lead, for example.

  When the container is a metal container, the container can also serve as either a positive electrode terminal or a negative electrode terminal.

  Next, an example of the nonaqueous electrolyte battery according to the second embodiment will be described in detail with reference to FIGS.

  FIG. 5 is a schematic perspective view of an example nonaqueous electrolyte battery according to the second embodiment. FIG. 6 is an exploded perspective view of one of the nonaqueous electrolyte batteries shown in FIG. FIG. 7 is a further exploded perspective view of the nonaqueous electrolyte battery shown in FIG.

  As shown in FIGS. 5 to 7, the nonaqueous electrolyte battery 100 of this example includes an exterior member 111, an electrode group 1 housed in the exterior member 111, and a nonaqueous electrolyte solution impregnated in the electrode group 1 ( (Not shown).

The electrode group 1 is the flat wound electrode group 1 described with reference to FIGS. In the electrode group 1, the portion excluding the portion 3d _p protruding from the electrode group 1 in the positive electrode uncoated portion 3d and the portion 4d _p protruding from the electrode group 1 in the negative electrode uncoated portion 4d are the insulating tape 10 It is covered with.

  As shown in FIGS. 5 to 7, the exterior member 111 includes a bottomed rectangular cylindrical metal container 111 a having an opening, and a rectangular plate-shaped sealing body 111 b disposed in the opening of the container 111 a. . The sealing body 111b is joined to the opening of the container 111a by welding such as laser welding. The sealing body 111b has two through holes (not shown) and an inlet (not shown).

  As shown in FIGS. 6 and 7, the nonaqueous electrolyte battery 100 of this example further includes a positive electrode lead 6 and a negative electrode lead 7.

  The positive electrode lead 6 includes a connection plate 6a having a through hole 6b, and a current collecting portion 6c that is bifurcated from the connection plate 6a and extends downward. Similarly, the negative electrode lead 7 includes a connection plate 7a having a through hole 7b, and a current collecting portion 7c branched from the connection plate 7a and extending downward.

  As shown in FIG.6 and FIG.7, the insulator 8 is arrange | positioned at the back surface of the sealing body 111b. The insulator 8 has a first recess 8a and a second recess 8b on the back surface. A through hole 8a ′ and a through hole 8b ′ are opened in the first recess 8a and the second recess 8b, respectively, and each of the through holes 8a ′ and 8b ′ communicates with the through hole of the sealing body 111b. doing. A connection plate 6a for the positive electrode lead 6 is disposed in the first recess 8a, and a connection plate 7a for the negative electrode lead 7 is disposed in the second recess 8b. The insulator 8 has a through hole 8c communicating with the inlet of the sealing body 111b.

The positive electrode lead 6, between the collector portion 6c of the bifurcated, it is joined thereto across the outer periphery of the portion 3d _p of the electrode group 2 positive electrode uncoated portion 3d. Moreover, the negative electrode lead 7, between the collector portions 7c of the bifurcated, it is joined thereto across the outer periphery of the portion 4d _p of the negative electrode uncoated portion 4d of the electrode group 2. Thus, the positive electrode lead 6 and the positive electrode 3 of the electrode group 2 are electrically connected, and the negative electrode lead 7 and the negative electrode 4 of the electrode group 2 are electrically connected.

As shown in FIGS. 6 and 7, the non-aqueous electrolyte battery 100 of this example includes two insulating members 9a. One of the insulating member 9a covers the junction between the portion 3d _p of the positive electrode lead 6 and the positive electrode uncoated portion 3d. Other insulating member 9a covers the junction between the portion 4d _p of the negative electrode lead 7 and the negative electrode uncoated portion 4d. The two insulating members 9a are each fixed to the electrode group 2 by an insulating tape 9b folded in half. The two insulating members 9a can also function as vibration absorbing members.

  As shown in FIGS. 5 to 7, the nonaqueous electrolyte battery 1 of this example further includes a positive electrode terminal 113 and a negative electrode terminal 114.

  The positive electrode terminal 113 includes a rectangular head portion 113a and a shaft portion 113b extending downward from the back surface of the head portion 113a. Similarly, the negative electrode terminal 114 includes a rectangular head portion 114a and a shaft portion 114b extending downward from the back surface of the head portion 114a. The positive electrode terminal 113 and the negative electrode terminal 114 are respectively disposed on the upper surface of the sealing body 111b via an insulating gasket 115. The shaft portion 113b of the positive electrode terminal 113 is inserted into the through hole 115a of the insulating gasket 115, the through hole of the sealing body 111b, the through hole 8a 'of the insulator 8, and the through hole 6b of the connection plate 6a of the positive electrode lead 6, It is fixed by caulking. The shaft portion 114b of the negative electrode terminal 114 is inserted into the through hole 115a of the insulating gasket 115, the through hole of the sealing body 111b, the through hole 8b ′ of the insulator 8, and the through hole 7b of the connection plate 7a of the negative electrode lead 7, They are caulked and fixed. Thereby, the positive electrode terminal 113 and the positive electrode lead 6 are electrically connected, and the negative electrode terminal 114 and the negative electrode lead 7 are electrically connected.

  In the nonaqueous electrolyte battery 100 having the above-described configuration, the nonaqueous electrolyte was injected into the container 111a after the electrode group 1 was accommodated and the sealing body 111b was joined to the opening of the container 111a. Can be done through the inlet. After injecting the nonaqueous electrolyte, as shown in FIG. 5, the exterior member 111 can be sealed by fitting a metal sealing plug 123 into the inlet and welding it.

  The nonaqueous electrolyte battery according to the second embodiment described above includes the electrode group according to the first embodiment. Therefore, the nonaqueous electrolyte battery according to the second embodiment can exhibit excellent rate characteristics and cycle characteristics.

[Example]
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)
In Example 1, a battery was manufactured using a nonaqueous electrolyte having the same structure as that of the nonaqueous electrolyte battery 100 shown in FIGS.

<Production of negative electrode>
As the negative electrode active material, a powder of lithium titanium oxide (Li ₄ Ti ₅ O ₁₂ ) having a spinel structure capable of inserting and extracting lithium at a potential of 1.55 V (vs. Li / Li ⁺ ) was used. A negative electrode mixture containing 90% by weight of this negative electrode active material, 5% by weight of acetylene black as a conductive agent, and 5% by weight of polyvinylidene fluoride (PVdF) as a binder. Prepared. This negative electrode mixture was added to N-methylpyrrolidone (NMP) to prepare a slurry for preparing a negative electrode. The slurry for preparing a negative electrode was prepared by dispersing the slurry for 2 hours in an atmosphere having a dew point of −20 ° C.

The slurry for preparing a negative electrode thus prepared is applied to an aluminum foil (negative electrode current collector) having a thickness of 15 μm so that the coating width is 204 mm and the coating amount per unit area is 60 g / m ^2. It was applied to. At this time, a band-shaped portion where the negative electrode slurry was not applied on the surface was left on the negative electrode current collector 5a. Next, the negative electrode current collector coated with the slurry for preparing the negative electrode was dried and then subjected to press treatment. Furthermore, the uncoated part of the negative electrode was slit and the width was adjusted to 13 mm. Thus, a strip-shaped negative electrode including a negative electrode current collector including a negative electrode uncoated portion having a width of 13 mm and an area ratio of 0.064 to the area of the negative electrode coated portion and a negative electrode layer was produced.

<Preparation of positive electrode>
Lithium nickel cobalt manganese oxide (LiNi _0.33 Co _{0.33 Mn 0.33} O ₂ ) powder was used as the positive electrode active material. A positive electrode mixture containing 90% by weight of this positive electrode active material, 5% by weight of acetylene black, and 5% by weight of polyvinylidene fluoride (PVdF) was prepared. This positive electrode mixture was added to NMP to prepare a slurry for preparing a positive electrode. The slurry for preparing the positive electrode was prepared by dispersing the slurry for 2 hours in an atmosphere having a dew point of −20 ° C.

This positive electrode preparation slurry was applied to an aluminum foil (positive electrode current collector) having a thickness of 15 μm so that the coating width was 200 mm and the coating amount per unit area was 60 g / m ² . At this time, a band-like portion where the positive electrode slurry was not applied on the surface was left on the positive electrode current collector. Next, the positive electrode current collector coated with the positive electrode preparation slurry was dried, and then subjected to press treatment. Furthermore, the uncoated part of the electrode was slit and the width was adjusted to 15 mm. Thus, a belt-like positive electrode having an uncoated part width of 15 mm and a ratio to the coated part area of 0.075 was produced.

<Battery assembly>
Two strip-shaped porous separators made of cellulose having a thickness of 7 μm and a width of 213 mm were prepared. The positive electrode produced previously was covered with one separator. At this time, a part of the positive electrode uncoated portion of the positive electrode was exposed from the separator.

  Next, the previously prepared negative electrode was stacked so as to face the positive electrode through a separator. At this time, the long side direction of the positive electrode and the long side direction of the negative electrode were combined. Moreover, it overlapped so that a part of negative electrode uncoated part of a negative electrode might protrude from a laminated body in the direction opposite to a positive electrode uncoated part.

  Next, the negative electrode was further covered with the other separator. At this time, a part of the negative electrode uncoated portion of the negative electrode was exposed from the separator. Thus, a laminate was obtained.

  The laminate was wound in a spiral shape with a winding axis as a winding axis parallel to the direction of the short side of the positive electrode and the negative electrode. Thus, a spiral electrode group was produced. This electrode group was subjected to pressing and formed into a flat shape.

  After molding, the ratio of the length of the exposed portion of the negative electrode uncoated portion in the same direction to the length of the electrode group in the winding axis direction was 0.036. Similarly, the ratio of the length of the exposed portion of the positive electrode uncoated portion in the same direction to the length of the electrode group in the winding axis direction was 0.036.

<Preparation of non-aqueous electrolyte>
A non-aqueous electrolyte was prepared by mixing and dissolving 1.0 M LiPF ₆ in a non-aqueous solvent consisting of 33 vol% ethylene carbonate (EC) and 67 vol% diethyl carbonate (DEC).

<Battery assembly>
In the flat electrode group produced previously, the positive electrode lead was electrically connected to the exposed portion of the positive electrode uncoated portion. Similarly, the negative electrode lead was electrically connected to the exposed portion of the negative electrode uncoated portion.

  Next, an aluminum lid having a thickness of 0.3 mm was prepared. This lid body was provided with a positive electrode terminal and a negative electrode terminal insulated from the lid body by a gasket. Subsequently, a positive electrode lead was connected to the positive electrode terminal of the lid. Similarly, a negative electrode lead was connected to the negative electrode terminal of the lid.

  The electrode group electrically connected to both terminals of the lid was inserted into a can-shaped container made of aluminum having a thickness of 0.3 mm and sealed with the previous lid. The size of the battery was 25.0 cm in width, 2.5 cm in thickness, and 11.0 cm in height (not including terminals). Thus, the nonaqueous electrolyte battery of Example 1 having a rated capacity of 45.2 Ah was assembled.

<Initial charge and recharge>
The battery was charged at a 0.2 C rate until the battery voltage reached 2.8 V, and left at 2.8 V for 3 hours. At this time, the charge rate of the battery was set to 100%, that is, full charge. Thereafter, the nonaqueous electrolyte battery was discharged at a 0.2 C rate until the battery voltage became 1.5V. The battery was then recharged so that the charge rate was 50%.

<Measurement of initial discharge capacity>
Subsequently, this battery was charged and discharged for 1 cycle at a 1C rate in an environment of 30 ° C., and the discharge capacity at this time was measured to obtain the initial discharge capacity. The results are shown in Table 2. Then, it charged again and adjusted the charging rate to 50%. In addition, the electric current value per hour which divided the charging capacity at the time of charging a single cell to a full charge voltage by charging time was set to 1C.

<Rate test>
Next, the nonaqueous electrolyte battery was charged in a 30 ° C. environment so that the charging rate was 100%, then discharged at a 1C rate until the battery voltage reached 1.5 V, and the capacity was recorded. Subsequently, this nonaqueous electrolyte battery was charged again so that the charging rate became 100%, and then discharged at the discharge current 5C rate in the same manner, and the capacity was recorded. The ratio of the discharge capacity at the 5C rate to the discharge capacity at the 1C rate was defined as the rate characteristic. The results are shown in Table 2 below.

<Cycle test>
After the rate test, the battery was charged to 2.8 V at a 1C rate in an environment of 30 ° C., and left at 2.8 V for 1 hour. Subsequently, after resting for 30 minutes, the battery was discharged at a 1C rate until the battery voltage reached 1.5V. Subsequently, it was rested for 30 minutes. The above charging / discharging was made into 1 cycle. This cycle was performed 300 times. After 300 cycles, the battery was charged and discharged for another cycle at a 1C rate. The discharge capacity at this time was measured, and the ratio of the discharge capacity to the initial discharge capacity was defined as cycle characteristics. The results are shown in Table 2 below.

<Measurement of dimensions>
Each dimension of the nonaqueous electrolyte battery after the cycle test was measured by the method described above. The results and the parameters obtained from the results are summarized in Tables 1 and 5 below.

(Examples 2-12 and Comparative Examples 1-6)
The batteries of Examples 2 to 9 and Comparative Examples 1 to 6 manufactured as shown below were tested in the same manner as in Example 1, and the dimensions were measured in the same manner as in Example 1.

(Examples 2 and 3)
In Examples 2 and 3, non-aqueous electrolyte batteries of Examples 2 and 3 were produced in the same manner as in Example 1 except that the separator material was changed to that shown in Table 2.

(Examples 4 and 5)
In Examples 4 and 5, non-aqueous electrolyte batteries of Examples 4 and 5 were produced in the same manner as in Example 1 except that the thickness of the separator was changed to that shown in Table 2.

(Examples 6 to 8)
In Examples 6-8, the widths of the coated part and the uncoated part in the negative electrode and the positive electrode were changed to those shown in Table 1, and the separator width and the exterior material size were changed in the same manner as in Example 1. The nonaqueous electrolyte batteries of Examples 6 to 8 were produced.

Example 9
In Example 9, the nonaqueous electrolyte battery of Example 9 was performed in the same manner as in Example 1 except that the number of wrinkles of the electrode group shown in Example 1 was changed, the thickness was increased, and the exterior material size was changed. Was made.

(Example 10)
In Example 10, in the slit after electrode coating, the area ratio of the negative electrode uncoated part and the area ratio of the positive electrode uncoated part were changed to those shown in Table 1, respectively, except that the separator width was changed to 210 mm. Produced the nonaqueous electrolyte battery of Example 10 in the same manner as Example 1.

(Example 11)
In Example 11, in the slit after electrode coating, the area ratio of the negative electrode uncoated part and the area ratio of the positive electrode uncoated part were changed to those shown in Table 1, respectively, except that the separator width was changed to 216 mm. Produced a nonaqueous electrolyte battery of Example 11 in the same manner as in Example 1.

Example 12
In Example 12, a nonaqueous electrolyte battery of Example 12 was produced in the same manner as in Example 1 except that the separator width was changed to 213 mm.

(Example 13)
In Example 13, in the slit after electrode coating, the area ratio of the negative electrode uncoated part and the area ratio of the positive electrode uncoated part were changed to those shown in Table 1, respectively, in the same manner as in Example 1. A nonaqueous electrolyte battery of Example 12 was produced. In the nonaqueous electrolyte battery of Example 9, the area of the positive electrode layer was larger than the area of the negative electrode layer.

(Examples 14 and 15)
In Examples 14 and 15, nonaqueous electrolyte batteries of Examples 14 and 15 were produced in the same manner as in Example 1 except that the porosity of the separator was changed to that shown in Table 2.

(Examples 16 and 17)
In Comparative Examples 16 and 17, the width of the coated part and the width of the uncoated part in the positive electrode and the negative electrode were changed to those shown in Table 1, and the separator width and the exterior material size were changed as in Example 1. Thus, the nonaqueous electrolyte batteries of Comparative Examples 16 and 17 were produced.

(Examples 18 and 19)
In Examples 18 and 19, non-aqueous electrolyte batteries of Examples 18 and 19 were produced in the same manner as in Example 1 except that the porosity of the separator was changed to that shown in Table 2.

(Comparative Example 1)
In Comparative Example 1, a nonaqueous electrolyte battery of Comparative Example 1 was produced in the same manner as in Example 1 except that the separator thickness was changed to 15 μm.

(Comparative Example 2)
In Comparative Example 2, a nonaqueous electrolyte battery of Comparative Example 2 was produced in the same manner as Example 1 except for the following points.

  The width of the negative electrode coating part at the time of electrode coating was set to 182 mm, and the width of the negative electrode uncoated part after the slit was set to 20 mm to prepare a negative electrode. The ratio of the area of the negative electrode uncoated part to the area of the negative electrode coated part was 0.11.

(Comparative Example 3)
In Comparative Example 3, a nonaqueous electrolyte battery of Comparative Example 3 was produced in the same manner as Example 1 except for the following points.

  A positive electrode was produced by setting the width of the positive electrode coating width at the time of electrode coating to 186 mm and the width of the positive electrode uncoated portion after slitting to 24 mm. The ratio of the area of the positive electrode uncoated part to the area of the positive electrode coated part was 0.13.

(Comparative Example 4)
In Comparative Example 4, a nonaqueous electrolyte battery of Comparative Example 4 was produced in the same manner as in Example 1 except that the separator material was changed to a polyethylene porous separator that was a polyolefin material. (Comparative Example 5)
In Comparative Example 5, a nonaqueous electrolyte battery of Comparative Example 5 was produced in the same manner as in Example 1 except that the negative electrode material was changed to carbon. In Comparative Example 5, the negative electrode slurry was applied to a copper foil (negative electrode current collector) having a thickness of 15 μm so that the application amount per unit area was 40 g / m ² . The widths of the negative electrode coated part and the negative electrode uncoated part were the same as in Example 1. In Comparative Example 5, the application conditions of the positive electrode slurry were the same as those in Example 1. Thus, a nonaqueous electrolyte battery of Comparative Example 5 having an initial capacity similar to that of the nonaqueous electrolyte of Example 1 was produced.

(Comparative Example 6)
In Comparative Example 6, a nonaqueous electrolyte battery of Comparative Example 6 was produced in the same manner as in Example 1 except that the negative electrode material was changed to carbon and the thickness of the separator was changed to 30 μm. In Comparative Example 6, the negative electrode slurry was applied to a copper foil (negative electrode current collector) having a thickness of 15 μm so that the application amount per unit area was 80 g / m ² . The widths of the negative electrode coated part and the negative electrode uncoated part were the same as in Example 1. In Comparative Example 6, the positive electrode slurry was applied to an aluminum foil (positive electrode current collector) having a thickness of 15 μm so that the application amount per unit area was 120 g / m ² . Thus, a nonaqueous electrolyte battery of Comparative Example 6 having an initial capacity similar to that of the nonaqueous electrolyte of Example 1 was produced.

<Result>
Tables 1 to 5 below summarize the results of dimensional measurements and battery and characteristic tests performed on the nonaqueous electrolyte batteries of Examples 1 to 19 and Comparative Examples 1 to 6.

  From the results of Table 5, it can be seen that all of the nonaqueous electrolyte batteries of Examples 1 to 19 achieved both high rate characteristics and cycle characteristics. This result is due to the following reason. First, in the nonaqueous electrolyte battery of the example, heat generation during charging and discharging was efficiently used, and an increase in resistance could be suppressed. As a result, the capacity hardly deteriorated even at a large current of 5C rate. Furthermore, the nonaqueous electrolyte batteries of Examples 1 to 19 had a small capacity deterioration during the cycle test. This is probably because the nonaqueous electrolyte batteries of Examples 1 to 19 were able to suppress local deterioration by uniformly diffusing the heat generated during the cycle test into the battery. Thanks to these, the nonaqueous electrolyte batteries of Examples 1 to 19 were able to suppress cycle deterioration due to heat generation while improving rate characteristics by heat generation.

  When comparing the results of Examples 1 to 19 and Comparative Example 1, the non-aqueous electrolyte battery of Comparative Example 1 was inferior in rate characteristics and cycle characteristics as compared to the non-aqueous electrolyte batteries of Examples 1 to 19. I understand. This is presumably because the non-aqueous electrolyte battery of Comparative Example 1 had a separator as thick as 15 μm, and the heat generated during charging / discharging could not be uniformly diffused into the battery. In addition, it is surmised that the nonaqueous electrolyte battery of Comparative Example 1 also had an increase in resistance due to the thick separator, and as a result, was not excellent in rate characteristics.

  Comparing the results of Examples 1 to 19 and Comparative Example 2, it can be seen that the non-aqueous electrolyte battery of Comparative Example 2 was inferior in rate characteristics as compared to the non-aqueous electrolyte batteries of Examples 1 to 19. In Comparative Example 2, since the width of the negative electrode uncoated portion was 20 mm and the ratio of the area of the negative electrode uncoated portion to the area of the negative electrode coated portion was 0.11, It is considered that the rate characteristics were lowered because the amount of heat generated in the electric part was small, the temperature of the battery did not increase during charging and discharging, and the resistance did not decrease. Furthermore, in Comparative Example 2, the positive electrode coating end portion did not face the negative electrode, and current concentration occurred in this portion, so that the partial deterioration was caused in the positive electrode coating end portion, and the cycle characteristics deteriorated. Conceivable.

  Comparing the results of Examples 1 to 19 and Comparative Example 3, it can be seen that the non-aqueous electrolyte battery of Comparative Example 3 was inferior in rate characteristics as compared to the non-aqueous electrolyte batteries of Examples 1 to 19. In Comparative Example 3, since the ratio of the area of the positive electrode uncoated part to the area of the positive electrode coated part was 0.13, the ratio of the area of the positive electrode coated part was low, and the positive electrode current collector during the rate test was This is thought to be because the heating value of the part was small, the temperature of the battery did not increase during charging / discharging, and the resistance did not decrease. Furthermore, in Comparative Example 3, it is considered that the negative electrode coating portion area is smaller than the rated capacity of the battery, and the current density is increased, so that the negative electrode load is increased and the cycle characteristics are deteriorated.

  When the results of Examples 1 to 19 and Comparative Example 4 were compared, it was found that Comparative Example 4 was particularly deteriorated in cycle characteristics. This is considered to be caused by the use of a separator using a polyolefin resin with low heat resistance, resulting in deterioration of the physical properties of the separator due to heat generation during charge and discharge, which led to an increase in resistance.

  Comparing the results of Examples 1 to 19 and Comparative Examples 5 and 6, it can be seen that Comparative Examples 5 and 6 exhibited significantly inferior cycle characteristics with respect to the cycle characteristics of the Examples. In particular, in Comparative Example 5, it was considered that an internal short circuit occurred during the cycle, and it was substantially impossible to charge and discharge after the cycle. In Comparative Example 5, by repeating the charge / discharge cycle, lithium dendrite was deposited on the surface of the carbon negative electrode, and this lithium dendrite broke through the 7 μm thick separator, causing a short circuit between the positive electrode and the negative electrode. Conceivable. From this result, it was found that it is difficult to use a separator having a thickness related to the example in the carbon negative electrode material. Moreover, even if it was the comparative example 6 which made the separator thick and prevented the short circuit, it turned out that cycle deterioration is still large. This is presumably because the deterioration of the carbon negative electrode progressed and the cycle characteristics deteriorated in an environment where heat generation during charging and discharging was large.

  The electrode group according to at least one of the embodiments and examples described above includes a negative electrode and a separator excellent in heat resistance, and the positive electrode layer and the negative electrode so that excessive heat generation can be suppressed although heat is likely to be generated. Contains layers. The negative electrode contains lithium titanate, and the separator has a thickness of 3 μm to 9 μm. Thanks to this, when this electrode group is used in a non-aqueous electrolyte battery, it is possible to prevent the battery characteristics from being deteriorated, and furthermore, heat can be used effectively. Therefore, this electrode group can realize a nonaqueous electrolyte battery excellent in rate characteristics and cycle characteristics.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

1 ... electrode group, 3 ... positive electrode, 3a ... cathode current collector, the long sides of 3a _L ... cathode current collector, 3a _W ... short side of the positive electrode current collector, 3b ... positive electrode layer, end faces of 3b _e ... positive electrode layer , 3c ... Seikyokunuriko unit, 3d ... positive electrode uncoated portion, 3d _p ... part of the positive electrode uncoated portion, 4 ... negative electrode, 4a ... negative electrode current collector, 4a _L ... long sides of the anode current collector, 4a _W ... short side of negative electrode current collector, 4b ... negative electrode layer, 4b _e ... end face of negative electrode layer, 4c ... negative electrode coated part, 4d ... negative electrode uncoated part, 4d _p ... part of negative electrode uncoated part DESCRIPTION OF SYMBOLS 5 ... Separator, 6 ... Positive electrode lead, 6a ... Connection plate, 6b ... Through-hole, 6c ... Current collection part, 7 ... Negative electrode lead, 7a ... Connection plate, 7b ... Through-hole, 7c ... Current collection part, 8 ... Insulation Body, 8a ... first recess, 8a '... through hole, 8b ... second recess, 8b' ... through hole, 8c ... through hole, 9a ... insulating member, 9b ... insulating tape, 10 ... insulating tape, 1 DESCRIPTION OF SYMBOLS 0 ... Nonaqueous electrolyte battery, 111 ... Exterior member, 111a ... Container, 111b ... Sealing body, 113 ... Positive electrode terminal, 113a ... Head, 113b ... Shaft part, 114 ... Negative electrode terminal, 114a ... Head part, 114b ... Shaft part 115 ... Insulating gaskets, 115a ... through holes, 123 ... sealing plugs.

Claims (7)

A negative electrode including a negative electrode current collector and a negative electrode layer formed on a part of the surface of the negative electrode current collector and including lithium titanium oxide;
A positive electrode including a positive electrode current collector and a positive electrode layer formed on a part of the surface of the positive electrode current collector;
Arranged between the negative electrode layer and the positive electrode layer, at least selected from the group consisting of cellulose, polyimide, polyamideimide, polyethersulfone, polyetherketone, polybenzimidazole, wholly aromatic polyester, and aromatic polyamide Including a separator having a thickness of 3 μm or more and 9 μm or less,
The negative electrode current collector is a strip having a pair of long sides,
The negative electrode current collector includes a negative electrode coated part carrying the negative electrode layer on the surface and a negative electrode uncoated part not carrying the negative electrode layer on the surface, and the negative electrode coated part and the negative electrode The uncoated parts are next to each other,
The negative electrode uncoated portion includes one long side of the pair of long sides of the negative electrode current collector,
The ratio of the area of the negative electrode uncoated part to the area of the negative electrode coated part is 0.05 or more and 0.07 or less,
The positive electrode current collector includes a positive electrode coated portion carrying the positive electrode layer on the surface, and a positive electrode uncoated portion not carrying the positive electrode layer on the surface,
The ratio of the area of the positive electrode uncoated part to the area of the positive electrode coated part is 0.07 or more and 0.09 or less.   The electrode group according to claim 1, wherein an area of the negative electrode coating portion is larger than an area of the positive electrode coating portion. The positive electrode current collector has a strip shape having a pair of long sides,
The positive electrode uncoated portion includes one long side of the pair of long sides of the positive electrode current collector,
The electrode group according to claim 2, wherein in the positive electrode current collector, the positive electrode uncoated portion is adjacent to the positive electrode coated portion. The electrode group is a wound electrode group,
A portion including the one long side of the negative electrode uncoated portion and a portion including the one long side of the positive electrode uncoated portion protrude from the electrode group in directions opposite to each other. And
The ratio of the length of the electrode group in the direction perpendicular to the one long side included in the negative electrode uncoated part to the length of the part of the negative electrode uncoated part protruding from the electrode group is The electrode group according to claim 2, wherein the electrode group is 0.03 or more and less than 0.05.   The electrode group according to claim 2, wherein the separator has a porosity of 50% or more and 80% or less. The electrode group according to claim 1;
A non-aqueous electrolyte battery comprising: a non-aqueous electrolyte.   The non-aqueous electrolyte battery according to claim 6, wherein the rated capacity is 10 Ah or more and less than 50 Ah.

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