WO2016147967A1

WO2016147967A1 - Secondary cell

Info

Publication number: WO2016147967A1
Application number: PCT/JP2016/057267
Authority: WO
Inventors: 山田　直毅; 木舩　素成; 英毅篠原
Original assignee: 日立オートモティブシステムズ株式会社
Priority date: 2015-03-17
Filing date: 2016-03-09
Publication date: 2016-09-22
Also published as: JP2018077931A

Abstract

To provide a means for positioning a secondary cell by engagement, etc., with a surrounding component, and facilitating measures against acceleration and vibration during travel. This secondary cell 1 has a cell container 2, which comprises a film-shaped packaging body 21, and a lid plate 3 for hermetically sealing the opening part 2D of the cell container 2, wherein the secondary cell 1 is characterized in that the opening edge of the opening part 2D of the cell container 2 is fixed to the side surface of the lid plate 3 and the lid plate 3 has an exposed part, which is exposed from the cell container 2, on the side surface of the lid plate 3.

Description

Secondary battery

The present invention relates to the structure of a lithium ion secondary battery used as a power source for automobiles, for example.

In recent years, lithium ion secondary batteries have been used as power sources for electric vehicles and hybrid vehicles. Lithium ion secondary batteries for automobiles are required to have high output, high energy density, and long life. In addition, the required capacity is much larger than secondary batteries used in personal computers and portable devices.

Also, when mounted on an automobile, it is required to efficiently install a battery in a limited space. For example, a laminate structure has been proposed from the viewpoint of the degree of freedom of shape.

However, various safety measures are required for secondary batteries for automobiles. For example, it is important to use a battery with high rigidity in order to ensure impact resistance. For example, the laminate structure has a lower strength than the can structure alone, and there is a concern that the impact resistance around the terminal portion for electrical connection is particularly low. For this reason, for example, Patent Document 1 proposes a structure having a lid having terminal parts.

JP 2006-318671 A

However, in the structure of Patent Document 1, the exterior material is fixed over the entire surface with respect to the side surface of the lid. Therefore, since the flexible resin layer covers the surface except for the upper surface which is the exposed portion of the cover plate, the dimensional accuracy is lowered and it is difficult to use the holder.

In particular, lithium ion secondary batteries for automobiles need to determine their position by engaging with surrounding parts to cope with vibration and acceleration during driving. However, the exterior material covers the entire side surface of the lid plate. In the fixed secondary battery, there is no part that can ensure dimensional accuracy other than one side of the cover plate located outside the secondary battery, it is difficult to use the holder, and it can cope with the vibration and acceleration. Is difficult.

The present invention solves the above-mentioned conventional problems. For example, the position of a lithium-ion secondary battery for automobiles is determined by engaging with peripheral parts, etc., and it is easy to deal with vibration and acceleration during driving. It aims at providing the means to do.

As means for solving the above-mentioned problems, the secondary battery of the present invention is a secondary battery having a battery container constituted by a film-shaped package and a lid plate for hermetically sealing the opening of the battery container. The battery container has an opening edge of the opening of the battery container fixed to a side surface of the lid plate, and the lid plate has an exposed portion exposed from the battery container on a side surface of the lid plate. It is characterized by having.

According to the secondary battery of the present invention, the position in the direction along the surface of the cover plate can be determined by contact or engagement with peripheral components. Therefore, for example, when mounted on an automobile, it is possible to provide a secondary battery that can easily cope with vibration and acceleration during traveling. Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

1 is an external perspective view of a secondary battery according to a first embodiment of the present invention. The disassembled perspective view of the secondary battery shown in FIG. The figure explaining the structure of a cover plate. The figure explaining the fixation structure to the cover plate of a battery container. The perspective view which showed the basic composition of the winding body. The disassembled perspective view explaining the holding method to the holder of the secondary battery of this invention. Sectional drawing which shows the holding | maintenance state to the holder of the secondary battery of this invention. The B section enlarged view of FIG. The figure explaining the structural example of a battery container. The figure explaining the other structural example of a battery container. The figure explaining the modification of the battery container shown in FIG. The figure explaining the other structural example of a battery container. The figure explaining the other structural example of a battery container. The figure explaining the other structural example of a battery container. The external appearance perspective view of the secondary battery in 2nd Embodiment of this invention. The figure explaining the structure of a cover plate. The figure explaining an example of the fixing structure of a battery container. The figure explaining other examples of the fixation structure of a battery container. The figure explaining other examples of the fixation structure of a battery container. The figure explaining the structure of the cover board in 3rd Embodiment of this invention. The figure explaining the structure of the cover board in 3rd Embodiment of this invention. The figure explaining the structure of the lithium ion secondary battery in 4th Embodiment of this invention.

Next, an embodiment of the present invention will be described.
<< First Embodiment >>
[1. Schematic configuration of battery]
FIG. 1 is an external perspective view of the secondary battery in the present embodiment, and FIG. 2 is an exploded perspective view of the secondary battery shown in FIG. FIG. 3 is a diagram for explaining the configuration of the lid plate, FIG. 3 (a) is a front view schematically showing the structure of the lid plate, and FIG. 3 (b) is a bottom view. And FIG. 4 is a figure explaining the fixing structure to the cover plate of a film-form package body.

The secondary battery 1 is a lithium ion secondary battery, and includes a battery container 2 that houses a wound body 4 that is a power generation element, and a lid plate 3 that closes and seals the opening 2D of the battery container 2. . The battery container 2 is configured by a film-shaped package, and the cover plate 3 is configured by a metal plate-shaped member having a predetermined plate thickness. The wound body 4 is supported on the cover plate 3 by the positive electrode side terminal component 5 and the negative electrode terminal component 6.

The film-like package 21 constituting the battery container 2 preferably has a laminated structure of a metal film and a resin film, or a laminated structure in which a resin layer is formed on the metal film. 4, a laminate material having a laminated structure in which resin layers 23 are formed on both surfaces of a metal film 22 is used. The material of the metal film 22 is preferably SUS or aluminum.

The battery container 2 has a bottomed box shape capable of storing an electrolytic solution. The battery case 2 includes a bottom surface 2A having a long side and a short side, a pair of

wide side surfaces

2B and 2B that stand up from the long side that is spaced apart from the bottom surface 2A, and a pair that stands up from the short side that is spaced from the bottom surface 2A. 2C and 2C, and a rectangular opening 2D that opens upward is formed at the top.

The battery container 2 using the film-shaped package 21 can be obtained, for example, by forming a single film-like member into a flat rectangular box shape with one surface opened by bending and welding or welding, or between Of the edge portions of the two film-shaped packages formed in such a manner that the power generation element can be sandwiched between them, the portions located other than the opening can be welded together.

As a welding method for assembling the battery container 2 from the film-shaped package 21, for example, in the film-shaped package 21 using aluminum as the metal film 22, the laminated resin layer 23 is heated to a melting point or higher and welded. Thermal welding is suitable. In the welding of aluminum, sufficient melting is difficult due to the thermal conductivity of aluminum, and there is a possibility that a uniform weld portion cannot be obtained and the hermeticity is lowered.

In the case of the film-like package 21 in which the SUS thin film is applied to the metal film 22, since the thermal conductivity of SUS is relatively low, in addition to the thermal welding of the resin layer 23, the material is suitable for welding. It is also possible to weld metal films by a technique such as laser welding or resistance welding. Thus, by metal-to-metal welding, the airtightness is high and it is possible to easily suppress the penetration of moisture and the like from the outside. As a welding method, laser welding is preferable from the viewpoint of position accuracy and workability.

The lid plate 3 is welded to the battery case 2 and hermetically seals the opening 2D of the battery case 2. The lid plate 3 is made of a metal material, and is preferably a SUS material or aluminum. In particular, when a film-like package 21 in which a SUS thin film is applied to a metal film is used for the battery container 2, the battery container 2 and The weldability of the battery is improved, and the sealing performance of the battery is increased.

As shown in FIG. 3A, the cover plate 3 includes a flat plate portion 10 having a certain thickness and ribs 11 provided so as to protrude from the lower surface of the flat plate portion 10. The flat plate portion 10 has a rectangular shape larger than the opening 2D of the battery case 2. The rib 11 constitutes a welded portion to which the battery case 2 is welded, and is continuously formed in a circumferential shape along the outer edge of the flat plate portion 10 as shown in FIG. Yes. The cover plate 3 has a side surface 10 a of the flat plate portion 10 and a rib outer surface 11 a of the rib 11 as side surfaces.

The rib 11 is provided at a position that is inward of the outer end edge portion of the flat plate portion 10 and at a position that is larger than the thickness of the film-shaped package 21 between the outer end edge portion of the flat plate portion 10. ing. The rib 11 is inserted into the battery container 2 from the opening 2D of the battery container 2, and the rib outer surface 11a has a size facing the inner wall surface of the battery container 2 over a predetermined height.

When welding the battery container 2 to the cover plate 3, first, the rib 11 of the cover plate 3 is inserted into the battery container 2 from the opening 2D of the battery container 2, and the opening end of the opening 2D of the battery container 2 is ribbed. It is made to oppose the outer surface 11a. And the laser beam of laser welding is irradiated toward the opening edge part from the outer side of the battery container 2. FIG. The laser beam is continuously irradiated over the entire circumference along the opening end of the battery case 2.

The battery container 2 is fixed by hermetically sealing the opening end of the opening 2D of the battery container 2 by being welded to the rib outer surface 11a of the rib 11 of the cover plate 3 by laser beam irradiation. A broken line WL shown in FIG. 1 schematically shows a welding mark by laser welding. In the battery container 2, the resin layer 23 where the laser beam of the film-shaped package 21 is irradiated by laser welding is evaporated, and the metal film 22 of the film-shaped package 21 is covered with the cover plate 3 as shown in FIG. 4. It is welded to the rib 11.

The cover plate 3 is exposed to the outside without being covered with the battery container 2 while the rib outer surface 11a of the rib 11 is covered with the battery container 2 among the side faces. Yes. That is, the side surface 10a of the flat plate portion 10 constitutes an exposed portion where at least a part of the side surface of the cover plate 3 is exposed to the outside. A side surface 10a of the flat plate portion 10 which is an exposed portion of the cover plate 3 serves as a reference point for lateral positioning of the lithium ion secondary battery 1 which is a direction along the lower surface 10b of the flat plate portion 10, and is made of metal. The cover plate 3 can be used for fixing. Therefore, the lithium ion secondary battery 1 can be positioned at a desired position, and the battery can be easily held.

If the side surface 10a of the flat plate portion 10 of the cover plate 3 is completely covered by the battery container 2 and is not exposed to the outside at all, the flexibility and smoothness of the resin layer 23 constituting the film-shaped package 21 are the main causes. As a result, the positioning accuracy of the lithium ion secondary battery is lowered, and the lithium ion secondary battery cannot be sufficiently fixed, and as a result, it may be difficult to hold. In particular, the welded portion does not have a uniform shape after welding and forms irregular irregular surfaces, so that it cannot be used as a reference surface for positioning and is difficult to reliably hold.

In the present embodiment, the battery case 2 is fixed to the rib 11 of the cover plate 3, and the side surface 10a of the flat plate portion 10 of the cover plate 3 is not covered with the battery case 2, but is exposed to the outside as an exposed portion. Therefore, the side surface 10a can be brought into contact with or sandwiched with another member, and can be used as a reference surface for positioning the lithium ion secondary battery 1. The flat plate portion 10 of the cover plate 3 has a constant shape of the side surface 10a and can improve the positioning accuracy of the lithium ion secondary battery 1 in the lateral direction.

In the present embodiment, the rib 11 is located at a position where the rib 11 enters the inner side of the outer end edge of the flat plate portion 10, and the gap between the rib 11 and the outer end edge of the flat plate portion 10 is larger than the thickness of the film-shaped package 21. Therefore, when the battery case 2 is fixed to the cover plate 3, the side surface 10 a of the flat plate portion 10 is arranged at a position protruding laterally from the battery case 2. Therefore, the side surface 10a can be easily brought into contact with another member, or the flat plate portion 10 can be sandwiched and held.

The cover plate 3 includes a positive electrode side terminal component 5 electrically connected to the positive electrode 34 of the wound body 4 and a negative electrode side terminal component 6 electrically connected to the negative electrode 32 of the wound body 4. Yes.

The positive electrode side terminal component 5 includes a positive electrode external terminal 51, a positive electrode connection terminal 52, a gasket (not shown) disposed inside the battery container 2, and a positive electrode current collector 53. The positive external terminal 51, the positive connection terminal 52, the gasket and the positive current collector 53 are fixed integrally and attached to the lid plate 3. In this state, the positive electrode current collector 53, the positive electrode connection terminal 52, and the positive electrode external terminal 51 are electrically connected. The positive electrode current collector 53, the positive electrode connection terminal 52, and the positive electrode external terminal 51 are insulated from the cover plate 3 by a positive electrode side external insulator (not shown) and a gasket.

On the other hand, the negative electrode side terminal component 6 includes a negative electrode external terminal 61, a negative electrode connection terminal 62, a gasket (not shown) disposed inside the battery container 2, and a negative electrode current collector 63. The negative electrode side terminal component 6 has the same structure as the positive electrode terminal component 5, and the negative electrode external terminal 61, the negative electrode connection terminal 62, and the negative electrode current collector 63 are integrally fixed and attached to the lid plate 3. ing. In this state, the negative electrode current collector 63, the negative electrode connection terminal 62, and the negative electrode external terminal 61 are electrically connected. The negative electrode current collector 63 and the negative electrode external terminal 61 are insulated from the cover plate 3 by a negative electrode side external insulator (not shown) and a gasket.

The positive external terminal 51 and the negative external terminal 61 protrude outside the cover plate 3 and have a screw structure. Therefore, when connecting the battery to an external circuit, the positive electrode external terminal 51 or the negative electrode external terminal 61 is inserted into a bus bar (not shown) provided with a hole or notch, and assembled with a nut. Thereby, a battery and an external circuit are electrically connected.

The cover plate 3 is provided with a gas discharge valve 71 as a safety valve. The gas discharge valve 71 is formed by partially thinning the cover plate 3 by press working. Note that a thin film member may be attached to the opening of the cover plate 3 by laser welding or the like, and the thin portion may be used as a gas discharge valve. The gas discharge valve 71 generates heat when the prismatic secondary battery 1 generates heat due to an abnormality such as overcharge, and the gas discharge valve 71 is cleaved when the pressure in the battery container increases and reaches a predetermined pressure. By discharging, the pressure in the battery container is reduced.

Further, the lid plate 3 is provided with a liquid injection hole 72 for injecting an electrolytic solution into the battery container. The liquid injection hole 72 is sealed by a liquid injection plug 73 after injecting the electrolytic solution. As the electrolytic solution, for example, a non-aqueous electrolytic solution in which a lithium salt such as lithium hexafluorophosphate (LiPF ₆ ) is dissolved in a carbonate-based organic solvent such as ethylene carbonate can be used.

FIG. 5 is a perspective view showing the basic configuration of the wound body 4, and shows a state where the winding end is disassembled.

The wound body 4 is produced by winding the positive electrode 34 and the negative electrode 32 with the

separators

33 and 35 being stacked therebetween. The positive electrode 34 and the negative electrode 32 are each composed of a positive electrode coated portion 34a and a positive electrode uncoated portion 34b in which a mixture layer is formed, and similarly, a negative electrode coated portion 32a and a negative electrode uncoated portion 32b. The portion where charging / discharging occurs due to insertion / extraction of lithium ions is performed, and the uncoated portion is a portion that mediates input / output of current to the battery by contacting or welding with an external terminal.

FIG. 6 is an exploded perspective view illustrating a method of holding the secondary battery according to the present invention to the holder, FIG. 7 is a cross-sectional view illustrating a state of holding the secondary battery according to the present invention to the holder, and FIG. It is the B section enlarged view of FIG.

Conventionally, a box-shaped battery can formed by subjecting a metal plate to a deep drawing process has been suitably used for lithium ion secondary batteries for automobiles in particular. This is because the use of a battery can increases the strength of the battery container and provides excellent dimensional accuracy when installing and fixing a jig around the periphery.

However, in the battery can, the thickness of the can wall is limited to about 0.5 mm, and it is difficult to make it thinner. The reason why it is difficult to make the film thinner is that, in the method by deforming the metal plate, there are a mixture of a part that tends to be thin in the manufacturing process and a part that tends to keep the original thickness relatively. Therefore, it is mentioned that the whole battery can has thickness variation.

Such a variation in the thickness of the can wall causes, for example, a bias in the pressure resistance of the battery container, and when the internal pressure of the battery rises, it ruptures from a specific part, and the contents erupt. The possibility of developing into a state increases. Further, in the process of obtaining the battery can, for example, when an additional process such as a rust prevention process is performed, the possibility that the thin part is physically broken increases, which may contribute to a decrease in yield.

As a solution to the problem conceived from the variation in the thickness of the can wall, there is a film-like package 21 applied to the battery container 2. Since the film-shaped packaging body 21 is previously formed into a thin film shape, when the box-shaped battery container 2 is produced using the film-shaped packaging body 21, the thickness variation of the box wall shall be extremely small. Can do. If the film-shaped package 21 can ensure the strength of the joint portion, the pressure resistance is less biased. Therefore, by providing a mechanism such as the gas discharge valve 71 for relieving the pressure at a specific part such as the cover plate 3, the battery container 2 with higher safety can be obtained.

The film-shaped package 21 is generally very flexible in terms of its structure, and there is a concern that the battery internal pressure tends to expand compared to the can structure obtained by the above-described deep drawing method. For this concern, for example, as shown in FIG. 6, a holder having a function of providing pressure resistance in addition to holding the lithium ion secondary battery 1 around the position where the lithium ion secondary battery 1 is installed. 7 is installed and the lithium ion secondary battery 1 is held, so that measures can be easily taken.

The holder 7 is made of a resin material such as reinforced plastic, and has a box shape that can accommodate the battery container 2. The holder 7 has an inner wall surface 7a that is opposed to the battery container 2 with a predetermined gap, and suppresses expansion of the battery container 2 by bringing the battery container 2 into contact with the inner wall surface 7a. be able to. On the upper surface of the holder 7, a step portion 7 b that can be engaged with the cover plate 3 is provided.

The stepped portion 7b contacts the lower surface 10b of the flat plate portion 10 by placing the lid plate 3, and performs positioning of the lithium ion secondary battery 1 in the thickness direction of the flat plate portion 10 in the height direction. In addition, the lateral positioning of the lithium ion secondary battery 1, which is in contact with the side surface 10 a of the flat plate portion 10 and is along the lower surface 10 b of the flat plate portion 10, is performed. Then, the lithium ion secondary battery 1 can be fixed to the holder 7 by inserting a screw through the through hole 8 formed in the flat plate portion 10.

The holder 7 suppresses the expansion of the battery container 2 made of the film-shaped package 21, thereby suppressing deformation of the lithium ion secondary battery 1 due to fluctuations in the battery internal pressure during use and designing the battery internal pressure when abnormal. When it rises above the value, for example, a pressure-sensitive current cutoff valve (not shown) installed on the lid plate 3 cuts off the current and stops the use of the battery. When the internal pressure further rises, the gas discharge valve 71 installed on the lid plate 3 is similarly ruptured and opened by the pressure, and measures such as preventing the battery itself from being ruptured by releasing the pressure can be taken.

By the way, secondary batteries used especially for in-vehicle applications etc. are used as assembled batteries in which two or more secondary batteries are connected in series in addition to being used alone because the required output is large. The possibility is high. In such a case, especially when using a square battery, the holders 7 that provide the pressure resistance described above are not individually installed, but, for example, the batteries are arranged so as to be in close contact with each other, and the surroundings have sufficient strength. It is also possible to adopt a form in which the secondary battery itself is used as a component that imparts pressure resistance to the adjacent secondary battery.

The holding method of the secondary battery 1 to the holder 7 is not only by engagement but also fixed by using a member that sandwiches the exposed portion of the cover plate 3, so-called clamp, or externally with respect to the cover plate 3 made of metal. Techniques such as welding and fixing metal parts can also be selected, and can be appropriately selected according to a desired fixing situation.

[2. Detailed battery configuration]
[2-1. Negative electrode]
The negative electrode 32 has a negative electrode mixture layer 32a on both surfaces of the negative electrode current collector. The negative electrode mixture layer 32a is formed on both surfaces of the negative electrode current collector through a slurry in which the negative electrode mixture is dissolved or dispersed in an appropriate solvent. As the solvent, an aqueous system or an organic system can be used. For example, water is used as the aqueous system, and N-methylpyrrolidone (hereinafter abbreviated as NMP) is preferable as the organic system, but as long as the slurry properties are not affected. Widely used organic solvents can also be used. For example, aromatic compounds such as toluene and xylene, aliphatic compounds such as hexane, ketone compounds such as acetone and methyl ethyl ketone, and alcohols may be used. . The negative electrode mixture has at least a negative electrode active material and a binder.

<Negative electrode active material>
The negative electrode active material is not particularly limited as long as it can occlude and release lithium ions, occludes lithium ions during battery charging, and releases them during discharging. A carbon material is particularly useful as a material that satisfies the above requirements and can ensure a practically necessary amount, and examples thereof include crystalline carbon and amorphous carbon. Among these, graphite, which is a kind of crystalline carbon, is preferable because it has a large amount of occlusion of lithium ions per unit weight. The negative electrode active material of the present invention preferably uses graphite powder as a main material.

Examples of graphite include natural graphite produced in addition to artificial graphite obtained by granulating and firing at high temperature using an organic material as a raw material. Artificial graphite is obtained by firing an organic compound as a raw material, but the maximum firing temperature exceeds 2000 ° C. A high firing temperature indicates a high heat cost during production. On the other hand, natural graphite is a carbon material that has already been graphitized, and does not require the above-mentioned firing process by being naturally produced. For this reason, the manufacturing cost of a negative electrode active material can be restrained cheaply.

It is known that graphite has a high reactivity at the edge surface of the graphite crystal structure exposed at the end face, and reacts with the electrolyte during charge / discharge of the secondary battery to decompose it. As a countermeasure, a method of forming a coating layer made of amorphous carbon on the surface of the graphite powder is known, and in this embodiment, the graphite powder having a coating layer made of amorphous carbon formed on the surface is also used. Is preferred. The coating layer made of amorphous carbon can be obtained by a technique in which petroleum or coal-based pitch is attached to the surface of graphite powder serving as a nucleus and baked at a temperature of 1000 ° C. or lower to form a carbon layer. In view of the above knowledge, since graphite can be prepared at a lower cost, it is preferable to mainly use a material obtained by applying natural carbon to amorphous graphite for the negative electrode active material of the present embodiment.

It should be noted that not only carbon-based materials but also materials having other compositions can be applied as long as the materials exhibit the above charge and discharge characteristics. For example, it is naturally possible to use a silicon-based, tin-based, or titanium oxide-based material that has an excellent lithium ion occlusion amount per unit weight. These materials usable as the negative electrode active material may be used alone or in combination of two or more. In the case of mixing, the ratio can be appropriately adjusted in accordance with desired electrode performance and consequently battery performance.

<Binder>
The shape of the negative electrode mixture layer according to the present embodiment is maintained by binding the negative electrode active materials to each other and / or the negative electrode active material and the current collector with a binder. The binder of the present invention is not particularly limited as long as it is a material that gives an aqueous slurry in which the material is dissolved and dispersed in water and enables the preparation of the negative electrode mixture layer.

It is essential that the binder contains a binder component that gives a binding force and a thickening component that adjusts the properties of the aqueous slurry. As the binder component, those having an olefinically unsaturated bond in the molecule are suitable, and the type is not particularly limited. For example, styrene butadiene rubber, styrene-isoprene-styrene rubber, acrylonitrile-butadiene rubber, styrene-acrylic copolymer are used. Examples thereof include polymers. Among these, styrene butadiene rubber (hereinafter abbreviated as SBR) is preferable from the viewpoint of availability. The thickening component is not particularly limited as long as it is difficult to handle when preparing the negative electrode mixture layer, but carboxymethyl cellulose (hereinafter abbreviated as CMC) is preferable from the viewpoint of chemical stability and availability. .

SBR is an artificial polymer whose main raw materials are styrene and 1,3-butadiene, and in order to obtain the desired properties, other organic compounds having an unsaturated bond can be added as desired to obtain desired properties. It can be a binder of characteristics. Usually, it is stored and used in the form of an emulsion in which particles having a diameter of less than 1 μm are dispersed in water.

The amount of SBR added is preferably 0.5 parts by mass or more and 2.0 parts by mass or less, more preferably 0.7 parts by mass or more and 1.5 parts by mass or less, with respect to the weight of the whole negative electrode mixture layer. 8 parts by mass or more and 1.2 parts by mass or less are more preferable. If the amount is less than 0.5 parts by mass, there is a strong possibility that the binding ability is significantly insufficient. If the amount exceeds 2.0 parts by mass, the binding ability becomes excessive, and the excess SBR inhibits the migration of lithium ions. The rise of becomes obvious.

CMC is a derivative obtained by chemically treating cellulose and imparting water solubility. Cellulose as a raw material is a polysaccharide in which β-glucose is linked in a chain and is a polymer obtained in nature. Cellulose itself has poor solubility and is insoluble in water and many organic solvents, but carboxymethylcellulose added with water solubility by chemical treatment can be dissolved in water and thickens the aqueous solution. High effect.

The amount of CMC added is preferably 0.5 parts by mass or more and 2.0 parts by mass or less, more preferably 0.7 parts by mass or more and 1.5 parts by mass or less, with respect to the total weight of the negative electrode mixture layer. 8 parts by mass or more and 1.2 parts by mass or less are more preferable. If the amount is less than 0.5 parts by mass, the stability of the aqueous slurry used in the production of the negative electrode is likely to be insufficient. If the amount exceeds 2.0 parts by mass, the thickening ability becomes excessive, making it difficult to apply the negative electrode during production. . Further, as in the case of SBR, an increase in DCR becomes obvious.

<Formation of negative electrode mixture layer>
The negative electrode mixture layer can be formed by a method of applying and drying a slurry on a current collector. Examples of the method for applying the slurry on the current collector include a knife coating method, a roll coating method, a spray coating method, a gravure coating method, a bar coating method, a curtain coating method, and a die coating method. Among them, the die coating method is preferable because the application amount can be easily adjusted and the uniformity is excellent. As a method for removing the solvent contained in the applied slurry, heat drying is preferable, and the drying temperature and drying time are appropriately adjusted according to the amount of slurry applied as long as the material contained in the mixture layer does not change in quality. It's okay.

The coating amount of the negative electrode mixture layer is not particularly limited as long as the desired battery performance can be achieved, and is preferably about 10 to 200 g after drying per square meter. If it is less than 10 g, coating becomes difficult and production becomes difficult. On the other hand, if it exceeds 200 g, the flexibility of the mixture layer becomes poor, and peeling from the current collector and destruction due to cracking of the mixture layer are likely to occur.

The desired mixture layer density can be adjusted by pressing the obtained mixture layer. Although there is no restriction | limiting in particular in the method of a press, A roll press is preferable from the productivity. The density after pressing is preferably 1.0 g or more and 3.0 g or less per cubic centimeter, more preferably 1.2 g or more and 2.0 g or less, and further preferably 1.4 g or more and 1.6 g or less. If it is less than 1.0 g, the electrical continuity between the active materials and / or the active material and the current collector becomes poor, and the active material with poor continuity makes it difficult to insert and desorb lithium ions during charge and discharge, and the battery capacity is reduced. Incurs a decline. On the other hand, when the amount exceeds 3.0 g, it is difficult to permeate the electrolytic solution, so that lithium ions are not sufficiently transported, and the battery performance may be deteriorated such as a decrease in capacity and an increase in DCR.

[2-2. Positive electrode]
The positive electrode 34 has a positive electrode mixture layer 34a on both surfaces of the positive electrode current collector. The positive electrode mixture layer 34a is formed on both surfaces of the positive electrode current collector through a slurry in which the positive electrode mixture is dissolved or dispersed in an appropriate solvent. As the solvent, an organic system is preferably used. For example, N-methylpyrrolidone (hereinafter abbreviated as NMP) is preferable, but a widely used organic solvent can be used as long as the slurry properties are not affected. For example, aromatic compounds such as toluene and xylene, aliphatic compounds such as hexane, ketone compounds such as acetone and methyl ethyl ketone, and alcohols may be used. The positive electrode mixture has at least a positive electrode active material and a binder.

<Positive electrode active material>
The positive electrode active material occludes and releases lithium ions in the non-aqueous electrolyte that the battery normally has, and takes in electrons. The physical properties and types of the positive electrode active material are arbitrary as long as the effects of the present invention are not significantly impaired. Therefore, a positive electrode active material having any known physical property that is preferably used for a non-aqueous electrolyte secondary battery may be used.

As the positive electrode active material, lithium oxide or the like can be mentioned as a suitable material. Specific examples of such lithium oxide include lithium cobalt oxide, lithium manganate, lithium nickelate, lithium iron phosphate, and lithium composite oxide (that is, two or more selected from the group consisting of cobalt, nickel, and manganese). Lithium oxide containing the above metal) and the like. A positive electrode active material may be used individually by 1 type, and may be used 2 or more types by arbitrary ratios and combinations.

<Positive electrode binder>
As the positive electrode according to the present embodiment, those having arbitrary physical properties can be used as long as the effects of the present invention are not significantly impaired. Examples thereof include a rubber binder similar to the negative electrode binder, and polyvinylidene fluoride (PVDF). In addition, 1 type of binders other than a rubber binder may be contained independently, and 2 or more types may be contained by arbitrary ratios and combinations.

<Formation of positive electrode mixture layer>
Like the negative electrode, the positive electrode mixture layer can be formed by applying a slurry on a current collector and drying it, and a die coating method is preferred. NMP is preferred as the solvent for the slurry. The method of removing the solvent contained in the applied slurry is also preferably heat-dried in the same manner as the negative electrode, and the drying temperature and drying time are appropriately determined according to the amount of slurry applied, as long as the material contained in the mixture layer is not altered. You may adjust.

The coating amount of the positive electrode mixture layer is not particularly limited as long as the desired battery performance can be achieved, and is preferably about 15 to 300 g after drying per square meter. If it is less than 15 g, coating becomes difficult and production becomes difficult. Moreover, when it exceeds 300 g, the softness | flexibility of a mixture layer will become scarce and it will be easy to produce the peeling | exfoliation from a collector, and the destruction by the crack of a mixture layer.

The desired mixture layer density can be adjusted by pressing the obtained mixture layer. Although there is no restriction | limiting in particular in the method of a press, A roll press is preferable from the productivity. The density after pressing is preferably 2.0 g or more and 4.0 g or less per cubic centimeter, more preferably 2.5 g or more and 3.5 g or less, and even more preferably 2.7 g or more and 3.3 g or less. If it is less than 2.0 g, the electrical continuity between the active materials and / or the active material and the current collector becomes poor, and the active material with poor continuity makes it difficult to insert and desorb lithium ions during charge and discharge, and the battery capacity is reduced. Incurs a decline. On the other hand, when the amount exceeds 4.0 g, it is difficult to permeate the electrolytic solution, so that lithium ions are not sufficiently transported and battery performance may be deteriorated.

<Negative electrode current collector and positive electrode current collector>
About the physical property and kind of the electrical power collector normally contained in the negative electrode 32 and the positive electrode 34 which concern on this embodiment, unless the effect of this invention is impaired remarkably, it is arbitrary. For example, the thickness of the negative electrode current collector is usually 4 μm or more, preferably 6 μm or more, and its upper limit is usually 20 μm or less, preferably 10 μm or less. The thickness of the positive electrode current collector is usually 5 μm or more, preferably 10 μm or more, and the upper limit is usually 20 μm or less, preferably 15 μm or less. If the thickness of the current collector is too thin, the strength of the electrode will decrease, and the electrode may be easily damaged. If it is too thick, the flexibility of the electrode will be impaired, and there will be restrictions on the battery manufacturing method in the subsequent process May occur.

Further, the type of the current collector is arbitrary as long as the effect of the present invention is not significantly impaired, but usually a conductive material is used. As such a current collector having conductivity, for example, copper or a copper alloy is suitably used for the negative electrode, and aluminum or an aluminum alloy is suitably used for the positive electrode. One type of current collector may be used alone, or two or more types may be used in any ratio and combination. Further, the shape of the current collector is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually a foil shape.

<Conductive material>
The conductive material assists the exchange of electrons between the current collector and the active material. The physical properties and types of the conductive material usually included in the negative electrode and the positive electrode according to the present embodiment are arbitrary as long as the effects of the present invention are not significantly impaired. Therefore, a conductive material having any known physical property that is suitably used for a non-aqueous electrolyte secondary battery may be used. Specific examples of such a conductive material include acetylene black and graphite. A conductive material may be used individually by 1 type, and may be used 2 or more types by arbitrary ratios and combinations.

<Other ingredients>
Examples of other materials included in the electrode mixture as needed include surfactants, antifoaming agents, and dispersing agents. When the electrode mixture contains a surfactant, the dispersion stability of each material contained in the slurry used for forming the mixture layer can be improved. Moreover, foaming at the time of apply | coating the slurry containing surfactant can be suppressed because an electrode mixture contains an antifoamer. Furthermore, when an electrode mixture contains a dispersing agent, aggregation of the active material contained in a slurry, and a conductive material etc. can be reduced when it contains. These additive components can be arbitrarily added as long as the effects of the present invention are not significantly impaired.

[2-3. Non-aqueous electrolyte]
The battery according to this embodiment usually has a non-aqueous electrolyte in addition to the binder. Such a nonaqueous electrolytic solution is not particularly limited as long as it can occlude and release lithium ions with respect to the active material.

The non-aqueous electrolyte usually consists of a non-aqueous solvent and a non-aqueous electrolyte. Any nonaqueous solvent may be used as long as the effects of the present invention are not significantly impaired. For example, a carbonate solvent is preferable. Specific examples of the carbonate solvent include cyclic carbonates such as ethylene carbonate (EC) and propylene carbonate (PC), and chain carbonates such as dimethyl carbonate (DMC) and methyl ethyl carbonate (MEC). A non-aqueous solvent may be used individually by 1 type, and may be used 2 or more types by arbitrary ratios and combinations.

Further, any nonaqueous electrolyte contained in the nonaqueous electrolytic solution can be used as long as the effects of the present invention are not significantly impaired. As a specific example of such a nonaqueous electrolyte, a lithium salt is particularly suitable. Specific examples of such a lithium salt include lithium fluorophosphate (LiPF ₆ ), lithium fluoroborate (LiBF ₄ ), and the like. In addition, a non-aqueous electrolyte may also be used individually by 1 type, and may use 2 or more types by arbitrary ratios and combinations.

A desired battery can be manufactured by combining the electrode and the non-aqueous electrolyte produced as described above.

[3-1. Example 1]
<Production of battery container>
The film-like package 21 in which SUS is applied to the metal film 22 was cut into a shape that takes into account the desired shape of the battery container 2 and the welding position. After cutting, a flat rectangular box with one side opened was obtained by bending. Furthermore, the edge part of the film-form package body 21 other than desired opening part 2D was connected with the site | part which opposes by laser welding, and the square can-shaped battery container 2 was obtained.

FIG. 9 is a diagram for explaining the configuration of a battery container formed by bending a single film-shaped package, FIG. 9A is a development view of the battery container, and FIG. 9B is a battery container. FIG. 9C is a cross-sectional view for explaining the sealing structure at the position C shown in FIG. 9A.

For example, as shown in FIG. 9A, the battery container 2 is formed by folding a film-like package 201 cut into a shape along a development view of a desired battery container 2 along a fold line BL and having a flat bottomed shape. It is assembled into a simple box shape. And the tab 202 which is a part which opposes and overlaps is joined by laser welding, and it seals so that electrolyte solution may not leak. Further, for example, as shown in part C of FIG. 9A, when the battery case 2 is assembled, pinholes may be formed at the corners of the bottom surface 2A. A resin 203 as shown in c) is applied and sealed.

<Production of lid plate>
Ribs 11 are provided on the lower surface 10 b of the cover plate 3 so as to follow the shape of the opening 2 D of the battery container 2. The material of the rib 11 was set to a composition similar to the SUS material included in the film-shaped package, and the weldability was improved. In addition, a gas discharge valve 71 is installed in the lid plate 3 to improve battery safety, and an abnormal increase in battery internal pressure is detected between the positive electrode connection terminal 52 and the positive electrode external terminal 51 to provide current. CID (current cutoff valve, not shown) was provided.

<Production of negative electrode>
Regarding the negative electrode 32, natural graphite, SBR, and CMC having an average particle diameter of 21 μm (D50) and a specific surface area of 3.9 × 10 ³ m ² / kg, which are coated with amorphous carbon, in a weight ratio. It mixed so that it might become 98.0: 1.0: 1.0. Finally, purified water was added to obtain an aqueous slurry having a solid content ratio of 50% by weight. The viscosity of the obtained slurry was 2.3 Pa · sec.

The viscosity was measured using a cone-plate viscometer according to JIS Z 8803. The slurry was applied to the surface of a copper foil having a thickness of 10 μm by a die coating method so that the coating amount was 95 g / m ² , sufficiently dried, further pressed, and a mixture density of 1.5 g / cm ^3. A negative electrode was prepared. The negative electrode 32 was provided with a negative electrode uncoated portion 32b having no mixture layer at the end on one side in the longitudinal direction of the coating, and was used as a portion to which a current collector component was attached during battery assembly described later.

<Preparation of positive electrode>
With respect to the positive electrode 34, nickel cobalt lithium manganate (chemical formula LiNi _1-xy Co _x Mn _y O _{2 as a} weight ratio Ni: Co: Mn = 5: 2: 3) as a positive electrode active material,
Scalar graphite, acetylene black as a conductive material, and PVDF as a binder are mixed at a weight ratio of 92: 4.5: 0.5: 3.0, and NMP is added as a dispersion solvent thereto. A kneaded positive electrode mixture was prepared. This positive electrode mixture was applied to the surface of an aluminum foil (positive electrode foil) having a thickness of 15 μm so that the coating amount on one side was 185 g / m ² and dried sufficiently. A positive electrode of 2.75 g / cm ³ was produced. Then, similarly to the negative electrode 32, an uncoated portion (positive electrode uncoated portion 34b) was provided at one end in the longitudinal direction of the positive electrode 34.

<Production of wound body>
The produced negative electrode 32 and the positive electrode 34 were wound with a separator placed between them so as not to contact each other, whereby a wound body 4 was obtained.

<Production of battery>
A positive electrode current collector 53 and a negative electrode current collector 63 as current collector parts were welded to the positive electrode uncoated part 34 b and the negative electrode uncoated part 32 b of the obtained wound body 4, and stored in the battery container 2. The opening 2D of the battery container 2 and the rib 11 of the lid plate 3 were brought into contact with each other and connected by laser welding to hermetically seal the battery container 2. Further, an electrolytic solution was injected from the liquid injection hole 72 to produce the lithium ion secondary battery 1.

<Shape of the obtained battery>
In the lithium ion secondary battery 1 obtained in this way, the side surface 10a of the cover plate 3 is exposed from the battery container 2, and constitutes an exposed portion. Therefore, the positioning accuracy with the holder 7 can be increased. In particular, high accuracy positioning and high vibration resistance can be realized by the combination with the holder 7 designed to engage the lid plate 3.

[3-2. Example 2]
<Production of battery container>
The two film-shaped packaging bodies 211 that are three-dimensionally formed face each other, and the wound body 4 is sandwiched between them. Of the edge portions of these two film-shaped packaging bodies 211, the position is other than the opening 2D. The parts to be welded were laser welded together to obtain a battery container 2.

FIG. 10 is a diagram for explaining another configuration of the battery container, in which FIG. 10 (a) is a perspective view showing an exploded state, and FIG. 10 (b) is a perspective view showing an assembled state.

The battery container 2 is configured by joining two three-dimensionally molded film-like packaging bodies 211. As shown in FIG. 10A, each film-like package 211 includes a flat portion 212 that forms the wide side surface 2B, a flat portion 213 that forms part of the narrow side surface 2C, and a portion of the bottom surface 2A. It has a plane part 214 to be configured. The

flat portions

213 and 214 have a width that is half the thickness width of the battery case 2. A flange 215 is provided at the edge of the

flat portions

213 and 214. As shown in FIG. 10B, the battery container 2 is formed by bringing the flanges 215 of the pair of film-shaped packaging bodies 211 into contact with each other and joining them by laser welding.

<Production of lid plate>
Similarly to Example 1, ribs 11 were provided on the flat plate portion 10 of the cover plate 3 along the opening 2D of the battery case 2. The gas discharge valve 71 and CID were also provided in the same manner as in Example 1.

<Production of battery>
Similarly to Example 1, the positive electrode current collector 53 and the negative electrode current collector 63 were welded to the wound body 4 and stored in the battery container 2. The opening 2D of the battery container 2 and the rib 11 of the lid plate 3 were brought into contact with each other and connected by laser welding to hermetically seal the battery. Further, an electrolytic solution was injected into the battery container 2 from the liquid injection hole 72 to produce the lithium ion secondary battery 1.

<Shape of the obtained battery>
In the lithium ion secondary battery 1 obtained in this way, the side surface 10a of the cover plate 3 becomes an exposed portion, and the positioning accuracy with the holder 7 is increased, similar to that obtained in Example 1. Can do. Highly accurate positioning and high vibration resistance can be realized by a combination with the holder 7 that is designed to be engaged.

11A and 11B are views for explaining a modification of the battery case shown in FIG. 10, FIG. 11A is a perspective view showing an assembled state, and FIG. 11B is a plan view showing an enlarged main part. It is.

In this modification, the flat portion 213 constituting the narrow side surface 2C is inclined with respect to the flat portion 212. As shown in FIG. 11B, the flat surface portion 213 is inclined so as to protrude in the lateral width direction as it approaches the flange 215 from the flat surface portion 212 constituting the wide side surface 2B. The rib 11 is also formed with the rib outer surface 11 a inclined so as to face the flat portion 213.

In the case of the structure shown in FIG. 10 described above, since the plane portion 213 is perpendicular to the plane portion 212, the angle between the pair of plane portions 213 overlapping each other is 180 degrees. Therefore, when it joins with the rib outer surface 11a of the cover plate 3, the clearance gap between the boundary part of the plane parts 213 and the rib outer surface 11a of the cover plate 3 becomes large, and there exists a possibility of affecting sealing property. .

On the other hand, according to the configuration shown in FIG. 11, the angle of the boundary portion between the flanges 215 is acute due to the inclination of the flat portion 213, and the rib outer surface 11 a of the cover plate 3 is also along the flat portion 213. Inclined. Therefore, the gap between the boundary portion of the pair of flat portions 213 and the rib outer surface 11a of the cover plate 3 can be reduced, and the battery case 2 can be sealed and sealed more reliably by the cover plate 3.

12 to 14 are diagrams for explaining another example of the configuration of the battery case.
The method of forming the battery container 2 is not limited to the method shown in FIGS. 10 and 11 and can be formed by various methods. For example, in the example shown in FIG. 12, it is formed by bending one sheet-like package body 21 into a U shape and binding both ends in the width direction. Binding ears 221 are provided on the pair of narrow side surfaces 2 C of the battery container 2.

And in the example shown in FIG. 13, it forms by joining the sheet-like package body 21 so that the inner wall surfaces of both ends may overlap, and making it a cylinder shape, and also binding the lower end used as the bottom face 2A. . A binding ear 222 is provided on one narrow side surface 2 C and bottom surface 2 A of the battery container 2.

Further, in the example shown in FIG. 14, one film-shaped package 21 is joined into a cylindrical shape so that the inner wall surface of one end 224 and the outer wall surface of the other end 225 overlap each other, and further, the bottom surface 2A It is formed by binding the lower ends. A binding ear 223 is provided on the bottom surface 2 A of the battery container 2.

According to the configuration shown in FIGS. 12 and 13, the length of the

binding ears

221 and 222 can be shortened and the sealing performance can be improved as compared with the battery container 2 shown in FIGS. 10 and 11. . According to the configuration shown in FIG. 14, the length of the binding ear 223 can be further shortened, and the battery container 2 can be downsized.

<< Second Embodiment >>
FIG. 15 is an external perspective view of a secondary battery according to the second embodiment of the present invention, FIG. 16 is a diagram illustrating the configuration of a cover plate, and FIG. 17 is a diagram illustrating an example of a battery container fixing structure. . The same components as those in the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.
What is characteristic in the present embodiment is that the battery container 2 is fixed to a lower region that is a part of the side surface 10 a of the flat plate portion 10 of the cover plate 3, and the upper region that is a part of the side surface 10 a is covered by the battery container 2. It is an exposed part that is exposed to the outside without breaking.

Similarly to the first embodiment, the lithium ion secondary battery 1 includes a battery container 2 that houses a wound body 4 (see FIG. 2), and a lid plate 3 that closes an opening 2D of the battery container 2. The battery container 2 is configured by a film-shaped package 21, and the cover plate 3 is configured by a metal material having a composition similar to the metal film 22 of the film-shaped package 21.

In the present embodiment, the flat plate portion 10 of the cover plate 3 has a substantially constant thickness, and the rib 11 (see FIG. 2) in the first embodiment is not provided. The flat plate part 10 has a size that can be inserted into the opening 2D of the battery case 2, has a thickness larger than that of the first embodiment, and has a wide side surface 10a. The side surface 10a has a lower region located on the lower surface 10b side and an upper region located on the front surface 10c side.

The battery container 2 is inserted with the cover plate 3 through the opening 2D, and the lower region of the side surface of the cover plate 3 is connected to the opening end of the battery container 2 as shown in FIGS. 16 (a) and 16 (b). It is arranged to face each other, and is arranged at a position where the upper region of the side surface 10a protrudes from the battery container 2 and is exposed.

Then, the open end of the battery container 2 is laser welded to the lower region of the side surface 10a of the cover plate 3 and hermetically sealed. The upper region of the side surface 10a of the cover plate 3 that hermetically seals the battery container 2 is not covered with the battery container 2, and constitutes an exposed portion that is exposed to the outside.

Therefore, the lithium ion secondary battery 1 can be positioned at a desired position using the upper region of the side surface 10a of the cover plate 3 as a reference point for lateral positioning of the lithium ion secondary battery 1, and the battery can be held. It becomes easy. The cover plate 3 is simpler and easier to make than the first embodiment, and the manufacturing cost can be reduced.

18 and 19 are diagrams illustrating another example of the battery container fixing structure.
In the above-described example, the case where the thickness of the cover plate 3 is thick has been described. For example, the cover plate 3 has a side surface fixed to the opening edge of the opening 2D of the battery container 2 and an exposed portion outside. It is only necessary to have an upper region that is exposed. In the example shown in FIGS. 18 and 19, the thickness of the flat plate portion 10 is as thin as in the first embodiment, but

ribs

12 and 13 are provided on the outer edge of the flat plate portion 10, and the side surface of the lid plate 3. Is extended or extended downward or upward. The flat plate portion 10 has a size that can be inserted into the opening 2D of the battery case 2. The side surface of the cover plate 3 is configured by a side surface 10 a of the flat plate portion 10 and rib

outer surfaces

12 a and 13 a of

ribs

12 and 13 that are flush with the side surface 10 a of the flat plate portion 10.

The rib 12 shown in FIG. 18 protrudes downward from the outer edge of the flat plate portion 10, and the rib outer surface 12 a is continuous with the side surface 10 a of the flat plate portion 10. In the case of the configuration shown in FIG. 18, the side surface of the cover plate 3 is configured by the side surface 10 a of the flat plate portion 10 and the rib outer surface 12 a of the rib 12, and the rib 12 side is a lower region welded to the battery container 2. The part 10 side is an upper region exposed to the outside.

The rib 13 shown in FIG. 19 protrudes upward from the outer edge of the flat plate portion 10, and the rib outer surface 13 a is continuous with the side surface 10 a of the flat plate portion 10. In the case of the configuration shown in FIG. 19, the side surface of the cover plate 3 is constituted by the side surface 10 a of the flat plate portion 10 and the rib outer surface 13 a of the rib 13, and the flat plate portion 10 side is a lower region welded to the battery container 2. The rib 13 side is an upper region exposed to the outside.

The cover plate 3 is inserted into the battery container 2 from the opening 2D, the lower region of the side surface of the cover plate 3 is disposed opposite the inner wall surface of the opening 2D of the battery container 2, and the upper region of the side surface of the cover plate 3 Is disposed at a position protruding from the battery container 2 and exposed. Then, the opening edge of the opening 2D of the battery container 2 is laser-welded to the lower region of the side surface of the cover plate 3 and hermetically sealed. The upper region of the side surface of the cover plate 3 is not covered with the battery container 2 and constitutes an exposed portion exposed to the outside.

Accordingly, similarly to the configuration shown in FIGS. 15 to 17, the upper region of the side surface of the cover plate 3 is used as a reference point for lateral positioning of the lithium ion secondary battery 1, and the lithium ion secondary battery 1 is placed at a desired position. Can be positioned, and the battery can be easily held. Compared with the configuration shown in FIGS. 15 to 17, the thickness of the flat plate portion 10 can be reduced, and the material cost can be reduced and the weight can be reduced.

<< Third Embodiment >>
20 and 21 are diagrams showing examples of the configuration of the lid plate according to the third embodiment of the present invention. In addition, detailed description is abbreviate | omitted by attaching | subjecting the same code | symbol to the component similar to the above-mentioned 1st and 2nd embodiment.

What is characteristic in this embodiment is that either one of the wide side surface 2B and the narrow side surface 2C of the battery case 2 protrudes from the side surface 10a of the flat plate portion 10 of the lid plate 3.

In the first embodiment described above, both the wide side surface 2B and the narrow side surface 2C of the battery case 2 are arranged on the inner side of the side surface 10a of the flat plate portion 10 of the lid plate 3, and the second embodiment Then, both the wide side surface 2 B and the narrow side surface 2 C of the battery container 2 are configured to protrude from the side surface 10 a of the flat plate portion 10 of the lid plate 3. On the other hand, in the present embodiment, one of the wide side surface 2B and the narrow side surface 2C of the battery container 2 has a configuration in which the side surface 10a of the flat plate portion 10 of the lid plate 3 protrudes.

In the configuration example shown in FIG. 20, the length in the long side direction of the flat plate portion 10 is the same as the length in the long side direction of the rib 11, and the side surface 10 a of the flat plate portion 10 and the rib outer surface 11 a of the rib 11 are short. Are continuously formed on the same plane. The battery case 2 is disposed at a position where the narrow side surface 2C of the battery case 2 protrudes from the battery case 2 as shown in FIGS. 20 (a) and 20 (c).

On the other hand, the length of the flat plate portion 10 in the short side direction is longer than the length of the rib 11 in the short side direction, and the side surface 10a of the flat plate portion 10 is longer than the rib outer surface 11a of the rib. Has been placed. As shown in FIG. 20B, the battery container 2 is disposed at a position where the side surface 10 a of the flat plate portion 10 of the cover plate 3 protrudes more laterally than the wide side surface 2 B of the battery container 2.

According to the configuration shown in FIG. 20 described above, the length in the long side direction of the flat plate portion 10 can be made shorter than in the first and second embodiments, and the size of the unit cell can be reduced. For example, when a plurality of lithium ion secondary batteries 1 are arranged in the thickness direction of the battery container 2 to form an assembled battery, the lid plates 3 of the lithium ion secondary batteries 1 adjacent to each other are connected to the side surfaces 10 a of the flat plate portion 10. Can be positioned by abutting.

In the configuration example shown in FIG. 21, the length in the short side direction of the flat plate portion 10 is the same as the length in the short side direction of the rib 11, and the side surface 10 a of the flat plate portion 10 and the rib outer surface 11 a of the rib 11 are long. Are continuously formed on the same plane. The battery case 2 is disposed at a position where the wide side surface 2B of the battery case 2 protrudes from the battery case 2, as shown in FIGS. 21 (a) and 21 (b).

On the other hand, the length in the long side direction of the flat plate portion 10 is longer than the length in the long side direction of the rib 11, and the side surface 10 a of the flat plate portion 10 protrudes from the rib outer surface 11 a of the rib 11 on the short side. Is arranged. As shown in FIG. 21 (c), the battery container 2 is disposed at a position where the side surface 10 a of the flat plate portion 10 of the cover plate 3 protrudes more laterally than the narrow side surface 2 C of the battery container 2.

According to the configuration shown in FIG. 21 described above, positioning can be performed by the side surface 10a of the flat plate portion 10 of the lid plate 3 protruding to the side from the narrow side surface 2C of the battery case 2. And the length of the short side direction of the flat plate part 10 can be shortened rather than 1st and 2nd embodiment, and size reduction as a unit cell can be achieved. For example, when a plurality of lithium ion secondary batteries 1 are arranged in the thickness direction of the battery container 2 to form an assembled battery, the adjacent battery containers 2 are brought into contact with each other to shorten the length in the column direction. Thus, the battery pack can be reduced in size.

<< Fourth Embodiment >>
FIG. 22 is a diagram for explaining the configuration of the lithium ion secondary battery according to the fourth embodiment. FIG. 22 (a) is a perspective view, and FIG. 22 (b) is an enlarged view of a main part from the front. It is. In addition, detailed description is abbreviate | omitted by attaching | subjecting the same code | symbol to the component similar to the above-mentioned 1st and 2nd embodiment.

What is characteristic in the present embodiment is that a notch is provided in the opening edge of the opening 2D of the battery container 2 to form an exposed portion in which the side surface of the cover plate 3 is partially exposed to the outside.
The battery container 2 is welded to the side surface 10 a of the flat plate portion 10 of the lid plate 3 with the opening edge of the opening portion 2 D disposed at the same height as the upper end of the rib 13. The battery case 2 has a notch 2E formed by partially notching the opening edge of the opening 2D. The notch 2E is provided on each of the pair of wide side surfaces 2B, and is formed at a central position in the long side direction. A part of the side surface of the cover plate 3 is exposed by the notch portion 2E of the battery container 2 to form an exposed portion. According to the configuration shown in FIG. 22 described above, the lithium ion secondary battery 1 can be positioned in the lateral direction with the exposed portion on the side surface of the cover plate 3 exposed from the notch 2E of the battery container 2 as a reference.

The lithium ion secondary battery 1 according to the present invention has a metal film-like package 21 in the battery container 2, has a high capacity, and uses the exposed portion on the side surface of the cover plate 3 to surround the surrounding members. It can be held with high positional accuracy, can withstand long-term use, and can be suitably used particularly for automobiles, railways and the like.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the spirit of the present invention described in the claims. It can be changed. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. Furthermore, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

DESCRIPTION OF SYMBOLS 1 Square secondary battery 2 Battery container 3 Cover plate 4 Winding body 7 Holder 10 Flat plate part 11-14 Rib 32 Negative electrode 34 Positive electrode

Claims

A secondary battery having a battery container constituted by a film-shaped package and a lid plate hermetically sealing the opening of the battery container,
The battery container has an opening edge of the opening of the battery container fixed to a side surface of the lid plate,
The secondary battery is characterized in that the cover plate has an exposed portion exposed from the battery container on a side surface of the cover plate.
The secondary battery according to claim 1, wherein the film-shaped package has a laminated structure of a metal film and a resin.
The lid plate is made of SUS material,
The secondary battery according to claim 2, wherein the metal film of the film-shaped package is a SUS thin film.
The secondary battery according to claim 3, wherein the battery container has an opening edge of an opening of the battery container fixed to a side surface of the lid plate by welding.
The lid plate has a flat plate portion having a shape larger than the opening of the battery container, and a rib projecting to a position on the back surface of the flat plate portion and inside the side surface of the flat plate portion, The secondary battery according to claim 4, wherein an opening edge of the opening of the battery container is fixed to a rib outer surface of the rib.
The lid plate has a flat plate portion having a predetermined plate thickness, and an opening edge of the opening of the battery container is located in a lower region located on the back side of the flat plate portion among the side surfaces of the flat plate portion. 5. The secondary battery according to claim 4, wherein an upper region that is fixed and located on a surface side of the flat plate portion is exposed to the outside from the battery container to constitute the exposed portion.
The lid plate includes a flat plate portion having a size that can be inserted into the opening of the battery container, and a rib that protrudes upward or downward from an outer edge of the flat plate portion. A lower region in which a side surface is configured by a side surface of the flat plate portion and a rib outer surface of the rib that is flush with the side surface of the flat plate portion, and is located on the back surface side of the flat plate portion among the side surfaces of the lid plate The opening edge of the opening part of the battery container is fixed to the upper surface, and the upper region located on the surface side of the flat plate part is exposed to the outside from the battery container to constitute the exposed part. Item 5. The secondary battery according to Item 4.
The battery container has a notch formed by partially cutting the opening edge of the opening of the battery container,
5. The secondary battery according to claim 4, wherein a part of a side surface of the cover plate is exposed by a notch portion of the battery container to form the exposed portion. 6.
The secondary battery according to any one of claims 1 to 8, wherein the cover plate has a safety valve.
The secondary battery according to any one of claims 1 to 8, wherein the lid plate has a current cutoff valve.