JP3799463B2 - Battery module - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a battery module, and more particularly to a battery module in which a plurality of non-aqueous secondary batteries for a power storage system are electrically connected in series and / or in parallel.
[0002]
[Prior art]
In recent years, from the viewpoint of effective use of energy aiming at resource saving and global environmental problems, attention has been focused on home-use distributed storage systems for the storage of late-night power storage and solar power generation, storage systems for electric vehicles, etc. Collecting. For example, Japanese Patent Laid-Open No. 6-86463 proposes a total system that combines electricity, gas cogeneration, fuel cells, storage batteries, and the like supplied from a power plant as a system that can supply energy to energy consumers under optimum conditions. ing. A secondary battery used in such a power storage system requires a large battery having a large capacity, unlike a small secondary battery for portable equipment having an energy capacity of 10 Wh or less. For this reason, in the above power storage system, a plurality of secondary batteries are usually stacked in series and used as an assembled battery having a voltage of 50 to 400 V, for example, and in most cases, lead batteries are used.
[0003]
On the other hand, in the field of small secondary batteries for portable devices, the development of nickel-metal hydride batteries and lithium secondary batteries as new batteries has progressed to meet the needs for small size and high capacity, and has a volumetric energy density of 180 Wh / l or more. Batteries are commercially available. In particular, a lithium ion battery has a possibility of a volume energy density exceeding 350 Wh / l, and reliability such as safety and cycle characteristics is superior to a lithium secondary battery using metallic lithium as a negative electrode. , Has dramatically expanded its market.
[0004]
In response, in the field of large-scale batteries for power storage systems, lithium-ion batteries are targeted as candidates for high-energy density batteries, and development is actively underway by the Lithium Battery Power Storage Technology Research Association (LIBES) and others. .
[0005]
The energy capacity of these large-sized lithium ion batteries is about 100 Wh to 400 Wh, and the volume energy density is 200 to 300 Wh / l, the same level as a small secondary battery for portable devices. The shape is typically a cylindrical shape having a diameter of 50 mm to 70 mm, a length of 250 mm to 450 mm, and a flat prismatic shape such as a square or oblong square having a thickness of 35 mm to 50 mm.
[0006]
When using the above-mentioned large battery for a power storage system, generally 4 to 10 large batteries (single cells) are connected in series to form a battery module of 15 to 50 V, and these battery modules are connected in series and in parallel. It is often used as a power storage system having a predetermined voltage and capacity.
[0007]
As for a thin lithium secondary battery, for example, a film battery in which a film having a thickness of 1 mm or less obtained by laminating metal and plastic is accommodated in a thin exterior (Japanese Patent Laid-Open Nos. 5-159757 and 7-57788). And a small prismatic battery having a thickness of about 2 mm to 15 mm (Japanese Patent Laid-Open Nos. 8-195204, 8-138727, 9-213286, etc.) are known. Each of these lithium secondary batteries has a purpose corresponding to the miniaturization and thinning of portable devices. For example, the lithium secondary battery has a thickness of several millimeters that can be stored on the bottom of a portable personal computer and has an area of about JIS A4 size. Although the thin battery which has is also disclosed (Unexamined-Japanese-Patent No. 5-283105), since an energy capacity is 10 Wh or less, a capacity | capacitance is too small as a secondary battery for electrical storage systems. Furthermore, when these thin batteries are connected in series and in parallel to form a battery module, since the capacity is small, heat dissipation is not taken into consideration, and no particular contrivance is made such as simple stacking.
[0008]
[Problems to be solved by the invention]
A large lithium secondary battery (with an energy capacity of 30 Wh or more) for a power storage system can obtain a high energy density, but its battery design is an extension of a small battery for portable devices, so the diameter or thickness is for portable devices. The shape of the battery is a cylindrical shape or a rectangular shape that is three times or more that of a small battery. In this case, heat is likely to be accumulated inside the battery due to Joule heat generation due to the internal resistance of the battery during charging and discharging, or internal heat generation of the battery due to change in entropy of the active material due to the entry and exit of lithium ions. For this reason, the temperature difference between the temperature inside the battery and the vicinity of the battery surface is large, and the internal resistance differs accordingly. As a result, variations in charge amount and voltage are likely to occur. In addition, since this type of battery is used as a plurality of assembled batteries, the ease of heat storage differs depending on the installation position of the batteries in the system, resulting in variations among the batteries, and accurate control of the entire assembled battery is possible. It becomes difficult. In addition, because of insufficient heat dissipation during high-rate charging / discharging, etc., the battery temperature rises, leaving the battery unfavorable, resulting in a decrease in life due to decomposition of the electrolyte, and thermal runaway of the battery. Problems such as induction of reliability, particularly safety, remained.
[0009]
In order to solve this problem, in an electricity storage system for an electric vehicle, an air cooling using a cooling fan, a cooling method using a Peltier device (Japanese Patent Laid-Open No. 8-148189), a method of filling a latent heat storage material inside a battery ( Japanese Patent Laid-Open No. 9-219213) is disclosed, but any of them is cooling from the outside, and cannot be said to be an essential solution.
[0010]
As a means for solving the above problem, a flat battery with a large surface area of the battery can be considered, but in the case of a flat battery, as the thickness of the battery is reduced, the front and back areas of the battery increase, The force for pressing the electrode to be stored is weakened. In particular, a large lithium secondary battery (energy capacity of 30 Wh or more) used in a power storage system has a strong tendency. For example, when considering a 100 Wh-class lithium ion battery having a thickness of 6 mm, the size of the front and back surfaces of the battery is 600cm ² Very large (one side).
[0011]
Further, in the above power storage system, a battery module that uses a plurality of single cells connected in series or in parallel is a basic unit, but there are few techniques for converting a flat battery into a battery module, and in particular, the force to hold down an electrode is low. In the case of a weak large-sized flat battery, there is a problem that the cycle deterioration due to the capacity reduction in high-rate discharge and repeated charge / discharge is large. It is difficult to solve such a problem only with a device structure of a single battery, and a solution in a battery module combining these batteries is required.
[0012]
An object of the present invention is to provide a battery module having good cycle characteristics and rate characteristics using an organic electrolyte battery for a power storage system having a large capacity of 30 Wh or more and a volume energy density of 180 Wh / l or more as a unit cell. .
[0013]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is arranged in a gap between a plurality of single cells that are electrically connected in series and / or in parallel and arranged with a gap of 1 mm or more in the thickness direction of the battery. At least one pressing member for pressing the unit cells on both sides, and the plurality of unit cells. Contain The unit cell includes a non-aqueous electrolyte including a positive electrode, a negative electrode, and a lithium salt, has a flat shape with a thickness of less than 12 mm, an energy capacity of 30 Wh or more, and a volume energy density of 180 Wh. / Non-aqueous secondary battery The at least one pressing member is arranged near the center of the unit cell, and the inner length of the exterior member in the thickness direction of the cell is the total thickness of the plurality of unit cells and the interval between the unit cells. The total thickness of the pressing members disposed in the gap is added, and at least a part of the exterior member is on the front and back sides of the unit cell disposed at both ends in the thickness direction of the battery. Located near the center The battery module characterized by the above is provided.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a battery module according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a configuration of a battery module according to an embodiment of the present invention.
[0015]
As shown in FIG. 1, the battery module includes an exterior member 500 and a plurality of single cells 401. In the exterior member 500, a plurality of unit cells 401 stacked via pressing members described below are accommodated and fixed. The plurality of unit cells 401 are electrically connected in series and / or in parallel, and are arranged with a gap of 1 mm or more in the thickness direction of the cells, and the gap between each unit cell is in contact with the unit cells on both sides. At least one or more members are arranged, and a module is formed by an exterior structure in which pressure is applied to each unit cell by the pressing member.
[0016]
Next, the exterior member shown in FIG. 1 will be described in more detail. FIG. 2 is a perspective view illustrating a configuration of the exterior member illustrated in FIG. 1.
[0017]
As shown in FIG. 2, the exterior member 500 includes six battery front and back beam members 501, six battery thickness direction beam members 502, and four vertical beam members 503. As shown in FIG. The structure of the exterior member shown in FIG. 2 is an example, and is not particularly limited to this example. However, any structure may be used as long as pressure can be applied to each single cell by a pressing member described below. It must be strong enough to withstand battery swelling.
[0018]
Further, the cross-sectional shape of the beam member 501 on the front and back surfaces of the unit cell has a shape in which both ends of the U-shape are further bent and extended as shown in FIG. There is no particular limitation on the example, and the quadrangle shown in FIG. 3B, the W shape shown in FIG. 3C, the circle shown in FIG. 3D, and the L shape shown in FIG. In particular, those obtained by bending a flat plate ((a) and (c) in FIG. 3) and L-shaped ((e) in FIG. 3) are preferable because they are lightweight and have high strength. Further, the beam member 502 on the battery thickness direction side can take various shapes similar to the above.
[0019]
In addition, the exterior member 500 uses a thick plate, a punching plate, or the like on the entire front and back sides of the unit cell, or uses a thick plate, a punching plate, or the like on the entire surface in the thickness direction of the battery. Various changes are possible, such as using a beam member, thick plate material, punching plate, etc., combining these, or increasing or decreasing the number of beam members, but when considering heat dissipation of the battery, As shown in FIG. 2, it is preferable to design so that the unit cell can be exposed to the outside air as much as possible. Further, as described above, since a higher pressure is required near the center of the unit cell, for example, as shown in FIG. 2, the beam member 501 on the front and back sides of the unit cell and the beam in the thickness direction side of the cell. It is preferable that at least one member 502 is designed in the vicinity of the center of the unit cell.
[0020]
The assembly of the exterior member 500 is not particularly limited, but fixing with bolts, welding, and the like are practical. Particularly, considering the ease of assembly and maintenance of the battery module, at least a part is fixed with bolts and removed. Preferably it is possible.
[0021]
Next, the pressing member will be described in more detail. FIG. 4 is a perspective view for explaining the positional relationship between the pressing member and the unit cell. In FIG. 4, for ease of explanation, a case where a pressing member is arranged between three unit cells will be described. However, even in the case of other number of unit cells, there is a pressing member between each unit cell. Arranged similarly.
[0022]
As shown in FIG. 4, three prismatic pressing members 402 are in contact with the unit cells on both sides in the gap between the unit cells 401a and 401b and the unit cell 401b and the unit cell 401c. Are arranged as follows.
[0023]
Since the unit cell used in the battery module of the present invention has a flat shape, the thickness of the cell is weakly pressed, and the thickness (near the central part C of the unit cell flat shape) during battery assembly or battery charging is weak. The thickness) tends to increase. Here, if the thickness of the pressing member 402 is u and the thickness of the unit cells 401a, 401b, and 401c is t, the distance between both ends of the three unit cells is 3t + 2u. Therefore, if the exterior member 500 is designed to be 3t + 2u, when the unit cells 401a, 401b, 401c are about to swell from the thickness t, the pressure member 402 applies pressure to the unit cells 401a, 401b, 401c.
[0024]
The pressing member 402 is not particularly limited to the above-described prism, and a cylinder, a hollow prism, a hollow cylinder, or the like can be used, and the cross-sectional shape is not particularly limited to a quadrangle, and is circular, disk-shaped, L-shaped. Various shapes such as a shape and a W shape can be used. A method for attaching the pressing member 402 is not particularly limited, and may be connected to the single cell by welding or the like, and can be fixed only by pressing with a combination with the exterior member.
[0025]
Further, as the pressing member 402, a member made of an elastic material (for example, rubber) or a member having an elastic structure (for example, a spring) can be used. For example, as shown in FIGS. 5A and 5B, spring plates 411 and 412 having elasticity in the arrow direction can be used as the pressing member. In this case, unlike the above-described pressing member having a shape such as a prism, the force for pressing the unit cells can be varied according to the size of the gap between the unit cells. In addition, since the spring plates 411 and 412 are flexible, they can be applied to various gap sizes between the single cells, and the spring plates 411 and 412 are free as long as the spring plates 411 and 412 contact at least the single cells on both sides. The exterior member can be designed.
[0026]
The gap between the single cells is 1 mm or more, preferably 2 mm or more and 12 mm or less, more preferably 2 mm or more and 8 mm or less. This gap is appropriately determined depending on the thickness, capacity, usage environment, usage, etc. of the unit cell. If this gap is too small, it will be difficult to sufficiently dissipate the heat generated by the unit cell. The volume of the module becomes large, which is not preferable. The gap can be further reduced when the battery module has a cooling structure such as a cooling fan or a heat sink. Moreover, also when using metals with high heat conductivity, such as aluminum or aluminum alloy, so that the pressing member also has a function as a heat sink, the gap between the single cells can be reduced.
[0027]
Although the arrangement position of the pressing member with respect to the unit cell is not particularly limited, it should be arranged so that the battery can be pressed uniformly. In particular, it is preferable that at least one pressing member is disposed in the vicinity of the central portion of the single cell because the central portion of the battery has a weak force for pressing the internal electrode in the single cell. In addition, by using the pressing member having elasticity as described above, the cell center can be pressed down more strongly than the periphery, so that the cells can be kept uniform.
[0028]
The area where the pressing member and the single cell come into contact is 50% or less, more preferably 30% or less, of the flat portion (front surface or back surface) of the single cell. When the area where the pressing member comes into contact exceeds 50%, it is difficult to sufficiently dissipate the heat generated by the unit cell, which is not preferable.
[0029]
In FIG. 4, three unit cells are arranged, but in the battery module of the present invention, two or more unit cells can be used. The desired number of cells is appropriately determined depending on the voltage, capacity, size, shape, voltage, capacity, shape, weight, etc. of the target storage battery system. Less than In addition, the cells of these single cells are generally connected in series or in parallel, but series connection and parallel connection may be mixed in one battery module.
[0030]
Next, the non-aqueous secondary battery that is a single battery will be described in more detail. FIG. 6 is a diagram showing a plan view and a side view of a flat rectangular (note type) non-aqueous secondary battery for power storage system used in the battery module of the present invention, and FIG. 7 is a diagram of the battery shown in FIG. It is a side view which shows the structure of the electrode laminated body accommodated in an inside.
[0031]
As shown in FIGS. 6 and 7, the non-aqueous secondary battery, which is a single battery, includes a battery case (battery container) including an upper lid 1 and a bottom container 2, and a plurality of positive electrodes housed in the battery case. 101a, negative electrodes 101b and 101c, and an electrode laminate including the separator 104. In the case of a flat type non-aqueous secondary battery, the positive electrodes 101a and the negative electrodes 101b (or the negative electrodes 101c arranged on both outer sides of the laminate) are alternately arranged via separators 104 as shown in FIG. However, the configuration of the unit cells is not particularly limited to this arrangement, and the number of stacks and the like can be variously changed according to the required capacity and the like.
[0032]
The positive electrode current collector of each positive electrode 101a is electrically connected to the positive electrode terminal 3 via the positive electrode tab 103a. Similarly, the negative electrode current collector of each negative electrode 101b, 101c is connected to the negative electrode terminal 4 via the negative electrode tab 103b. Is electrically connected. The positive terminal 3 and the negative terminal 4 are attached in a state insulated from the battery case, that is, the upper lid 1. The upper lid 1 and the bottom container 2 are welded all around the point A shown in the enlarged view of FIG. The upper lid 1 is provided with a safety valve 5 for releasing when the internal pressure inside the battery rises. The shape of the non-aqueous secondary battery shown in FIGS. 6 and 7 is, for example, 300 mm long × 210 mm wide × 6 mm thick. The lithium secondary battery uses a lithium composite oxide for the positive electrode 101a and a carbon material for the negative electrode. The energy capacity of about 80-100Wh
And can be used for the battery module.
[0033]
The positive electrode active material used for the positive electrode 101a is not particularly limited as long as it is a lithium-based positive electrode material, and lithium composite cobalt oxide, lithium composite nickel oxide, lithium composite manganese oxide, or a mixture thereof, A system in which one or more different metal elements are added to these composite oxides can be used, and a high voltage and high capacity battery can be obtained, which is preferable. Further, when safety is important, manganese oxide having a high thermal decomposition temperature is preferable. As this manganese oxide, LiMn ₂ O _Four Lithium composite manganese oxide, a system in which one or more different metal elements are added to these composite oxides, and LiMn in which lithium, oxygen, etc. are made in excess of the stoichiometric ratio ₂ O _Four Is mentioned.
[0034]
The negative electrode active material used for the negative electrodes 101b and 101c is not particularly limited as long as it is a lithium-based negative electrode material, and is a material capable of doping and dedoping lithium, such as safety and reliability such as cycle life. Is preferable. Examples of materials that can be doped and dedoped with lithium include graphite-based materials, carbon-based materials, tin oxide-based, silicon oxide-based metal oxides, and polyacene, which are used as negative electrode materials for known lithium ion batteries. Examples thereof include conductive polymers represented by organic organic semiconductors. In particular, from the viewpoint of safety, a polyacene-based substance that generates a small amount of heat at around 150 ° C. or a material containing the same is desirable.
[0035]
As the electrolyte of the non-aqueous secondary battery described above, a non-aqueous electrolyte containing a known lithium salt can be used, and is appropriately determined depending on the use conditions such as the positive electrode material, the negative electrode material, the charging voltage, and more specifically. LiPF ₆ , LiBF _Four LiClO _Four A lithium salt such as propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, dimethoxyethane, γ-butyl lactone, methyl acetate, methyl formate, or a mixture of two or more of these solvents. Etc. are exemplified. Further, the concentration of the electrolytic solution is not particularly limited, but generally 0.5 mol / l to 2 mol / l is practical, and naturally the electrolytic solution has a water content of 100 ppm or less. It is preferable to use it. In addition, the non-aqueous electrolyte used in this specification means a concept including a non-aqueous electrolyte solution and an organic electrolyte solution, and also refers to a concept including a gel-like or solid electrolyte.
[0036]
The material of the separator 104 is not particularly limited, and examples thereof include polyolefins such as polyethylene and polypropylene, polyamide, kraft paper, glass, and the like, and polyethylene and polypropylene are preferable from the viewpoints of cost, water content, and the like. Moreover, said separator can also use 1 type or multiple types of above, and the some separator may be laminated (adhered).
[0037]
The battery module using the non-aqueous secondary battery configured as described above can be used for a household power storage system (night power storage, cogeneration, solar power generation, etc.), a power storage system such as an electric vehicle, and the like. , Can have large capacity and high energy density. In this case, the energy capacity of the unit cell is preferably 30 Wh or more, more preferably 50 Wh or more, and the energy density is preferably 180 Wh / l or more, more preferably 200 Wh / l. When the energy capacity is less than 30 Wh, or when the volume energy density is less than 180 Wh / l, the battery module combined with the battery has a small capacity for use in an electricity storage system, and one capacity is required to obtain a sufficient system capacity. Since it is necessary to increase the number of battery modules in series / parallel or the number of battery modules, and it is difficult to achieve a compact design, it is not preferable for a power storage system.
[0038]
Moreover, the thickness of the flat non-aqueous secondary battery is preferably less than 12 mm, more preferably less than 10 mm, and even more preferably less than 8 mm. As for the lower limit of the thickness, 2 mm or more is practical in consideration of the filling factor of the electrode and the battery size (the area becomes larger in order to obtain the same capacity as the thickness is reduced). When the thickness of the battery is 12 mm or more, it becomes difficult to sufficiently dissipate the heat generated inside the battery to the outside, or the temperature difference between the inside of the battery and the vicinity of the battery surface increases, resulting in different internal resistances. The variation in the amount of charge and voltage in the battery increases. The specific thickness is appropriately determined according to the battery capacity and the energy density, but it is preferable to design with the maximum thickness that provides the expected heat dissipation characteristics.
[0039]
In addition, as the shape of the non-aqueous secondary battery, for example, the front and back surfaces of the flat shape can be various shapes such as a square shape, a circular shape, an oval shape, etc. It can also be a polygon such as a triangle or a hexagon. Furthermore, it can also be made into cylindrical shapes, such as a thin cylinder. In the case of a cylinder, the thickness of the cylinder is the thickness referred to here. Further, from the viewpoint of ease of manufacturing, the flat front and back surfaces of the battery are rectangular, and a notebook shape as shown in FIG. 6 is preferable.
[0040]
Next, as an example of a method for manufacturing a battery case including the upper lid 1 and the bottom container 2, a method for manufacturing a notebook battery case will be described. In general, a rectangular battery is a small consumer battery having a size of about 50 mm square and a thickness of about 6 mm. As shown in FIG. 8, a bottom container 21 (also serving as a negative electrode terminal) manufactured by deep drawing of a thick plate is used. It is manufactured by laser welding the upper lid 22 provided with a safety valve and a positive electrode terminal.
[0041]
However, in the case of the notebook type battery as shown in FIG. 6, it is difficult to manufacture by the same method as the small secondary battery, and the bottom container 2 of the battery case is a thin plate having the shape shown in FIG. Bending inward and then bending outward along the alternate long and short dash line L2, then welding the corner indicated by A, or manufacturing by thin plate drawing (very shallow drawing), terminals and safety valves are installed Further, the upper lid 1 is obtained by welding as shown in FIG. Moreover, it can also be manufactured by bending a thin plate as shown in FIG. 10 and welding the horizontal lids 11 and 12 to the structure 13 where the portion A is welded.
[0042]
The material used for the battery case such as the thin plate is appropriately selected depending on the use and shape of the battery, and is not particularly limited, and iron, stainless steel, aluminum and the like are common and practical. Further, the thickness of the battery case is appropriately determined depending on the use and shape of the battery or the material of the battery case, and is not particularly limited. Preferably, the thickness of the portion of 80% or more of the battery surface area (the thickness of the portion having the largest area constituting the battery case) is 0.2 mm or more. If the thickness is less than 0.2 mm, it is not desirable because the strength required for manufacturing the battery cannot be obtained. From this viewpoint, it is more preferably 0.3 mm or more. The thickness of the same part is desirably 1 mm or less. If the thickness exceeds 1 mm, the internal volume of the battery is reduced and a sufficient capacity cannot be obtained, or the weight increases, which is not desirable. From this viewpoint, the thickness is preferably 0.7 mm or less.
[0043]
As described above, by designing the thickness of the non-aqueous secondary battery to be less than 12 mm, for example, when the battery has a large capacity of 30 Wh or more and a high energy density of 180 Wh / l, a high rate charge / discharge, etc. However, the rise in battery temperature is small, and it can have excellent heat dissipation characteristics. Therefore, the heat storage of the battery due to internal heat generation is reduced, and as a result, it is possible to suppress the thermal runaway of the battery, and it is possible to provide a non-aqueous secondary battery excellent in reliability and safety. Measures for heat dissipation are easy, and the reliability and safety of the battery module can be improved.
[0044]
In addition, since the battery module of this embodiment can apply sufficient pressure to each unit cell and can maintain the unit cell in a uniform thickness, a battery module having excellent cycle characteristics and rate characteristics can be obtained. It is possible to obtain the good heat dissipation characteristics of the unit cell. The above battery module is used alone or in a plurality or more connected in series or in parallel to be used in a power storage system. In practice, a system for controlling the battery module is used as a side surface of the module as necessary. Alternatively, it can be installed on the upper surface or the like.
[0045]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples.
(Example)
(1) LiCo ₂ O _Four 100 parts by weight, 8 parts by weight of acetylene black and 3 parts by weight of polyvinylidene fluoride (PVDF) were mixed with 100 parts by weight of N-methylpyrrolidone (NMP) to obtain a positive electrode mixture slurry. The slurry was applied to both sides of a 20 μm thick aluminum foil serving as a current collector, dried, and then pressed to obtain a positive electrode. FIG. 11 is an explanatory diagram of electrodes. In this embodiment, the application area (W1 × W2) of the electrode 101 is 268 × 178 mm. ² It is applied to both sides of a 20 μm current collector 102 with a thickness of 95 μm. As a result, the electrode thickness t is 210 μm. In addition, an electrode is not applied to the end portion 1 cm of one short side of the current collector 102, and a tab 103 (aluminum having a thickness of 0.1 mm and a width of 6 mm) is welded.
[0046]
(2) 100 parts by weight of mesocarbon microbeads (MCMB, manufactured by Osaka Gas Chemical Co., No. 6-28) and 10 parts by weight of PVDF were mixed with 90 parts by weight of NMP to obtain a negative electrode mixture slurry. The slurry was applied to both sides of a 14 μm thick copper foil serving as a current collector, dried, and then pressed to obtain a negative electrode. Since the shape is the same as that of the above-described positive electrode, it will be described with reference to FIG. In this embodiment, the application area (W1 × W2) of the electrode 101 is 270 × 180 mm. ² It is applied to both surfaces of a 14 μm current collector 102 with a thickness of 105 μm. As a result, the electrode thickness t is 224 μm. In addition, an electrode is not applied to an end portion 1 cm of one short side of the current collector 102, and a tab 103 (nickel having a thickness of 0.1 mm and a width of 6 mm) is welded.
[0047]
Further, a single-sided electrode having a thickness of 119 μm was prepared by the same method except that the coating was applied to only one side. The single-sided electrode is disposed on the outside in the electrode laminate of item (3) (101c in FIG. 7).
[0048]
(3) The separator 104 (superposition of polyethylene-polypropylene nonwoven fabric and polypropylene microporous membrane) is applied to the eight positive electrodes and nine negative electrodes (two inner surfaces) obtained in the above item (1) as shown in FIG. Thus, an electrode laminate was prepared by alternately laminating.
[0049]
(4) The bottom container 2 of the battery (see FIG. 6) was made by drawing a 0.5 mm SUS304 thin plate to a depth of 5 mm. Further, the upper lid 1 of the battery was made of a thin plate made of SUS304 having a thickness of 0.5 mm. The upper lid is attached with positive electrode and negative electrode terminals 3, 4 (6mmφ) made of SUS304 and is provided with a safety valve hole (8mmφ). The positive electrode and negative electrode terminals 3, 4 are insulated from the upper lid 1 by a polypropylene packing. .
[0050]
(5) After welding each positive electrode tab 103a of the electrode laminate prepared in the above item (3) to the positive electrode terminal 3 and each negative electrode tab 103b to the negative electrode terminal 4 via a connecting wire, the electrode laminate is attached to the bottom container 2 Was fixed with an insulating tape, and the corner A in FIG. 6 was laser welded over the entire circumference. After that, LiPF was added to the concentration of 1 mol / l in a solvent in which ethylene carbonate and diethyl carbonate were mixed at a 1: 1 weight ratio as an electrolytic solution from the safety valve hole. ₆ The solution in which was dissolved was poured, and the lid was closed using an aluminum foil having a thickness of 0.1 mm.
[0051]
(6) The obtained battery was charged to 4.1 V with a current of 5 A, and then constant current and constant voltage charging in which a constant voltage of 4.1 V was applied was performed for 8 hours. Subsequently, the battery was discharged to 2.5 V with a constant current of 10A. The discharge capacity was 21.1 Ah. The temperature rise of the battery at the time of discharging was less than that of a box battery having the same capacity (battery having a thickness of 12 mm or more).
[0052]
(7) The capacity when charging and discharging were repeated 10 cycles under the same conditions as described above using the above battery was 19.8 Ah. Furthermore, in the 11th cycle, the battery was charged to 4.1 V with a current of 5 A, and then a constant current and constant voltage charge for applying a constant voltage of 4.1 V was performed for 8 hours. Subsequently, when the battery was discharged at a constant current of 20 A to 2.5 V, the capacity of the single cell was 11.8 Ah and the rate characteristics were insufficient.
[0053]
(8) Eight unit cells were used, arranged as shown in FIG. 12, and placed in the exterior member 500 shown in FIG. 2 to produce a battery module. Three pressing members 402 having a thickness of 3 mm and a width of 20 mm were inserted between the batteries at positions as shown in FIG. The position of the pressing member 402 was 20 mm from the center of the unit cell and the outside of the unit cell. Further, the beam member 501 on the front and back surfaces of the unit cell is a member (depth 4 mm, width 30 mm) formed by bending a 2 mm thick SUS304 flat plate so as to have the cross-sectional shape shown in FIG. ) Was used. As the beam member 502 on the thickness direction side of the battery, an aluminum plate having a thickness of 5 mm and a width of 30 mm was used. Further, as the vertical beam member 503, an L-shaped member made of SUS304 having a thickness of 2 mm and a width of 5 mm was used. Each beam member was fixed with bolts. The obtained battery module is designed so that the length in the thickness direction of the battery is 81 mm, the inner length of the exterior member 500 is 69 mm, and the distance between the both ends of the unit cell is 69 mm.
[0054]
(9) In the battery module obtained in (8), each single cell is connected in series, charged to 32.8V with a constant current of 5A, and then applied with a constant voltage of 32.8V. For 8 hours. Subsequently, the battery was discharged to 20V with a constant current of 10A. The discharge capacity was 20.7 Ah.
[0055]
(10) The capacity when charging / discharging was repeated 10 cycles under the same conditions using the unit cell of the battery module was 20.1 Ah. Furthermore, in the 11th cycle, the battery was charged to 32.8 V with a current of 5 A, and thereafter, constant current and constant voltage charging in which a constant voltage of 32.8 V was applied was performed for 8 hours. Subsequently, when the battery was discharged to 20 V with a constant current of 20 A, the capacity was 15.8 Ah, and the rate characteristics were improved as compared with the single cell.
(Comparative example)
A battery module was fabricated in the same manner as in the above example except that the pressing member was not used. The single cells were connected in series, charged to 32.8 V with a current of 5 A, and then subjected to constant current and constant voltage charging in which a constant voltage of 32.8 V was applied for 8 hours. Subsequently, the battery was discharged to 20V with a constant current of 10A. The discharge capacity was 20.4 Ah.
[0056]
Next, the capacity when charging / discharging was repeated 10 cycles under the same conditions using the unit cell of the battery module was 19.5 Ah. Furthermore, in the 11th cycle, the battery was charged to 32.8 V with a current of 5 A, and thereafter, constant current and constant voltage charging in which a constant voltage of 32.8 V was applied was performed for 8 hours. Subsequently, when the battery was discharged to 20 V with a constant current of 20 A, the capacity was 10.9 Ah and the rate characteristics were poor.
[0057]
【The invention's effect】
As is apparent from the above, according to the present invention, a highly safe organic electrolyte battery for a power storage system having a large capacity of 30 Wh or more and a volumetric energy density of 180 Wh / l or more, excellent heat dissipation characteristics, and used as a unit cell In the battery module for connecting a plurality of the unit cells, at least one pressing member for pressing the unit cells on both sides is disposed in the gap between the unit cells, thereby achieving good cycle characteristics and rate characteristics. be able to.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a configuration of a battery module according to an embodiment of the present invention.
2 is a perspective view showing a configuration of an exterior member shown in FIG. 1. FIG.
3 is a diagram showing an example of a cross-sectional shape of a beam member of the exterior member shown in FIG. 2. FIG.
FIG. 4 is a perspective view for explaining a positional relationship between a pressing member and a unit cell.
FIG. 5 is a perspective view showing an example of another pressing member.
6 is a diagram showing a plan view and a side view of a non-aqueous secondary battery for a power storage system that is an example of the single battery shown in FIG. 1. FIG.
7 is a side view showing a configuration of an electrode laminate housed in the battery shown in FIG. 6. FIG.
FIG. 8 is an explanatory diagram of a conventional method for manufacturing a small prismatic battery.
FIG. 9 is an explanatory diagram of an example of a manufacturing method of the bottom container shown in FIG.
FIG. 10 is an explanatory diagram of another example of a method for manufacturing a battery case of a non-aqueous secondary battery according to the present invention.
FIG. 11 is an explanatory diagram of a cell electrode used in an example of the battery module of the present invention.
FIG. 12 is an explanatory diagram of the arrangement of single cells used in the example of the battery module of the present invention.
[Explanation of symbols]
1 Upper lid
2 Bottom container
3 Positive terminal
4 Negative terminal
5 Safety valve
101 electrode
101a Positive electrode (both sides)
101b Negative electrode (both sides)
101c Negative electrode (single side)
102 Current collector
103 tabs
103a Positive electrode tab
103b Negative electrode tab
104 separator
111a positive electrode unit
111b negative electrode unit
111c single-sided negative electrode unit
401, 401a, 402b, 402c unit cell
402 Pressing member
500 Exterior member
501, 502, 503 Beam members

Claims (4)

A plurality of single cells that are electrically connected in series and / or parallel and arranged with a gap of 1 mm or more in the thickness direction of the battery;
At least one pressing member disposed in the gap between the unit cells, for pressing the unit cells on both sides;
An exterior member for housing and fixing the plurality of single cells,
The unit cell includes a nonaqueous electrolyte containing a positive electrode, a negative electrode, and a lithium salt, has a flat shape with a thickness of less than 12 mm, an energy capacity of 30 Wh or more, and a volume energy density of 180 Wh / l or more. der is,
At least one pressing member is disposed near the center of the unit cell,
The inner length of the exterior member in the thickness direction of the battery is a length obtained by adding the total thickness of the plurality of unit cells and the total thickness of the pressing members arranged in the gaps between the unit cells. ,
At least a part of the exterior member is disposed in the vicinity of the center of the front and back surfaces of the unit cell disposed at both ends in the thickness direction of the battery. The battery module according to claim 1, wherein a plate thickness of the battery container of the unit cell is 0.2 mm or more and 1 mm or less. The battery module according to claim 1, wherein a shape of the flat front and back surfaces of the unit cell is a rectangle. The battery module according to any one of claims 1 to 3, wherein an area where the pressing member and the unit cell come into contact is 50% or less of an area of a flat portion of the unit cell.

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