JP2022014718A - Secondary battery - Google Patents

Abstract

To provide a secondary battery in which even when a positive electrode collector terminal and a negative electrode collector terminal are drawn out from one side of a rectangular weld in an exterior body, the concentration of current in and a reduction in strength of the collector terminals can hardly occur.SOLUTION: A secondary battery 1 disclosed herein comprises: a laminated electrode body 30 in which plurality of positive electrodes and negative electrodes are laminated with separators therebetween; and an exterior body 10 for enclosing the laminated electrode body. The exterior body 10 has a rectangular weld 20, and part of a positive electrode collector terminal 40 and a negative electrode collector terminal 50 is drawn out from one side of the rectangular weld. Here, the collector terminals are adhered to each other with an insulating layer 70 therebetween, and at least any one of the width WP in the positive electrode collector terminal 40 and the width WN in the negative electrode collector terminal 50 is half or more the length L of a side in the laminated electrode body 30.SELECTED DRAWING: Figure 1

Description

The present invention relates to a secondary battery. More specifically, the present invention relates to a secondary battery including a laminated electrode body in which a plurality of positive electrodes and negative electrodes are laminated via a separator, and an exterior body for enclosing the laminated electrode body.

Secondary batteries such as lithium-ion secondary batteries and nickel-metal hydride batteries are becoming more important as power sources for vehicles mounted on electricity as a drive source, or power sources mounted on electric products such as personal computers and mobile terminals. In particular, lithium-ion secondary batteries, which are lightweight and have high energy density, are preferable as high-output power sources for driving vehicles such as electric vehicles (EVs), plug-in hybrid vehicles (PHVs), and hybrid vehicles (HVs), and will continue to be used in the future. Demand is expected to grow.

An example of such a secondary battery is a so-called closed-type secondary battery in which a plurality of positive electrodes and negative electrodes are laminated via a separator and an exterior body for enclosing the laminated electrode body is provided. Be done. One aspect of this type of sealed secondary battery is one provided with an exterior body made of a laminated film. Such an exterior body typically has an accommodating portion for accommodating the laminated electrode body and a rectangular welded portion that surrounds the accommodating portion in a sealed state around the accommodating portion, and tabs from the welded portion. The positive electrode current collecting terminal and the negative electrode current collecting terminal are pulled out. A typical example of a battery of this type is a non-aqueous electrolyte battery disclosed in Patent Document 1 below.

Japanese Unexamined Patent Publication No. 2001-305476

By the way, in a secondary battery used as a power source for driving a vehicle, so-called high-rate charging / discharging is often performed in which a large current is charged / discharged in a short time. It is known that such high-rate charging / discharging tends to cause current concentration at a current collector terminal or the like.
Here, for example, in a laminated film type secondary battery in which the positive electrode current collector terminal and the negative electrode current collector terminal are drawn from one side of a rectangular welded portion, the current collector terminal is used to prevent a short circuit due to contact between the current collector terminals. Tends to reduce the area of. Therefore, when such a laminated film type secondary battery is used, it is not preferable because a remarkable current concentration may occur at the current collecting terminal. In addition, the small area of the current collector terminal may reduce its strength.

The present invention has been made in view of such circumstances, and a main object thereof is that even when the positive electrode current collecting terminal and the negative electrode current collecting terminal are pulled out from one side of a rectangular welded portion in the exterior body, the positive electrode is used. It is an object of the present invention to provide a secondary battery in which current concentration in the current collector terminal and the negative electrode current collector terminal and their strength are less likely to decrease.

The following secondary batteries are provided in order to achieve the above-mentioned purposes.
The secondary battery disclosed here includes a laminated electrode body in which a plurality of positive electrodes and negative electrodes are laminated via a separator, and an exterior body for enclosing the laminated electrode body. Further, the exterior body has an accommodating portion for accommodating the laminated electrode body, and a rectangular welded portion surrounding the accommodating portion in a sealed state. A part of the positive electrode current collecting terminal and the negative electrode current collecting terminal electrically connected to the positive electrode and the negative electrode of the laminated electrode body is drawn out from one side of the rectangular welded portion. Here, at least a part of the positive electrode current collecting terminal and the negative electrode current collecting terminal is characterized in that they are adhered to each other via an insulating layer. Further, in a preferred embodiment, at least one of the positive electrode current collecting terminal and the negative electrode current collecting terminal has a width orthogonal to the drawn direction of half or more of the length in the width direction of the laminated electrode body. It is characterized by that.

According to the secondary battery having the above configuration, even when the positive electrode current collector terminal and the negative electrode current collector terminal are pulled out from one side of the rectangular welded portion in the exterior body, even if the battery has a relatively large capacity of the electrode body, the current collector can be collected. Since the size of the electric terminal can be secured relatively large, it is possible to more reliably prevent the current concentration in the current collecting terminal. Further, since the current collector terminals are adhered to each other via the insulating layer, the strength thereof is less likely to decrease.

It is a top view which shows typically the structure of the secondary battery which concerns on one Embodiment. It is explanatory drawing which shows typically the attachment structure of the current collector terminal in FIG. It is a top view which shows typically the structure of the conventional secondary battery. It is explanatory drawing which shows typically the attachment structure of the current collector terminal in FIG.

Hereinafter, preferred embodiments of the secondary battery disclosed herein will be described in detail with reference to the drawings as appropriate. It should be noted that matters other than those specifically mentioned in the present specification and necessary for implementing the technique disclosed herein (for example, a method for manufacturing a positive electrode and a negative electrode / a method for constructing a secondary battery, etc.) It can be grasped as a design matter of a person skilled in the art based on the prior art in the field. The technique disclosed herein can be carried out based on the contents disclosed in the present specification and the common general technical knowledge in the art.
The following embodiments are not intended to limit the techniques disclosed herein. Further, in the drawings shown in the present specification, the same reference numerals are given to the members / parts having the same action. The dimensional relations (length, width, thickness, etc.) in each drawing do not reflect the actual dimensional relations. Further, in the present specification and claims, when a predetermined numerical range is described as A to B (A and B are arbitrary numerical values), it means A or more and B or less. Therefore, it includes the case where it is above A and below B.

In the present specification, the "secondary battery" generally refers to a power storage device capable of being repeatedly charged and discharged, and is a term including a so-called storage battery and a power storage element such as an electric double layer capacitor. Further, in the following embodiments, an all-solid-state lithium-ion secondary battery is used as the secondary battery, but the technique disclosed here is not limited to the all-solid-state lithium-ion secondary battery, and other secondary batteries ( For example, it can be applied to a lithium ion secondary battery, a nickel hydrogen battery, etc.).

(1) Overall Configuration of Secondary Battery FIG. 1 is a plan view schematically showing the configuration of the secondary battery 1 according to the embodiment. As shown in FIG. 1, the secondary battery 1 according to the present embodiment roughly includes a laminated electrode body 30 in which a plurality of positive electrodes and negative electrodes are laminated via a separator, and the laminated electrode body. It is provided with an exterior body 10 for encapsulation. Hereinafter, each component will be described.

(2) Exterior body As shown in FIGS. 1 and 2, the exterior body 10 includes an accommodating portion 12 accommodating the laminated electrode body 30 and a rectangular welded portion 20 surrounding the accommodating portion in a sealed state. Has. As the exterior body 10, those used in this type of battery can be used without particular limitation. For example, from the viewpoint of physical strength, heat dissipation, and the like, a metal (for example, aluminum) exterior body can be used. Alternatively, an exterior body made of a laminated film can be used from the viewpoint of stackability, weight reduction, and the like. A preferred example of such a laminated film is a three-layer structure in which a metal layer (for example, aluminum) is interposed between two resin layers.

(3) Laminated Electrode Body FIG. 2 is an explanatory diagram schematically showing the mounting structure of the current collector terminal in FIG. 1. As shown in FIG. 2, in the present embodiment, two independent electrode body units (specifically, the first electrode body unit 32a and the second electrode body unit 32b) are connected in series as the laminated electrode body 30. Although laminated in the positive and negative electrode stacking direction is used, it is not intended to limit the laminated electrode body 30 to such a configuration. For example, the laminated electrode body 30 housed in the accommodating portion 12 may be provided with only one such electrode body unit, or may be provided with three or more such electrode body units. Hereinafter, the components constituting the laminated electrode body 30 will be described.

(I) Positive electrode As the positive electrode included in the laminated electrode body 30 according to the present embodiment, those used in this type of battery can be used without particular limitation. The positive electrode typically comprises a positive electrode current collector and positive electrode active material layers formed on both sides (or one side) thereof.
The positive electrode current collector is preferably made of a metal having good conductivity, and is made of a metal material such as aluminum, nickel, titanium, or stainless steel.
Further, the positive electrode active material layer contains a positive electrode active material and may further contain a solid electrolyte. Then, if necessary, a conductive material, a binder (binding agent) or the like may be contained. Examples of the positive electrode active material include composite oxides having a layered structure represented by LiCoO ₂ , LiNiO ₂ , and the like. Alternatively, examples thereof include a composite oxide having a spinel structure as represented by Li ₂ Nimn ₃ O ₈ and LiMn ₂ O ₄ , a composite compound having an olivine structure such as LiFePO ₄ . Further, as the solid electrolyte, the solid electrolyte exemplified in the following description of the solid electrolyte layer can be appropriately used.

(Ii) Negative electrode As the negative electrode included in the laminated electrode body 30 according to the present embodiment, those used in this type of battery can be used without particular limitation. The negative electrode typically includes a negative electrode current collector and a negative electrode active material layer formed on both sides (or one side) thereof.
The negative electrode current collector is preferably made of a metal having good conductivity, and is composed of, for example, nickel, copper (for example, copper foil), an alloy mainly composed of nickel or copper, or the like.
Further, the negative electrode active material layer contains a negative electrode active material and may further contain a solid electrolyte. Then, if necessary, a conductive material, a binder, or the like may be contained. Examples of the negative electrode active material include a carbon-based negative electrode active material such as graphite and carbon black, and a negative electrode active material containing silicon (Si) or tin (Sn) as a constituent element. Further, as the solid electrolyte, the solid electrolyte exemplified in the following description of the solid electrolyte layer can be appropriately used.

(Iii) Separator Since the secondary battery 1 according to the present embodiment is an all-solid-state battery, a solid electrolyte layer is used as the separator. As the solid electrolyte layer, those used in this type of battery can be used without particular limitation. The solid electrolyte layer typically contains a solid electrolyte, and may further contain a binder, various additives, and the like, if necessary.
As the solid electrolyte, various oxide-based solid electrolytes, sulfide-based solid electrolytes, and the like can be used. Examples of the oxide-based solid electrolyte include various oxides having a NASICON structure, a garnet-type structure, or a perovskite-type structure. In particular, from the viewpoint of having high ionic conductivity, it is preferable to use a sulfide-based solid electrolyte. Further, from the viewpoint of achieving higher ionic conductivity, it is preferable to use a Li _{2S -} based solid solution composed of Li 2S and lithium halide (for example, LiCl, LiBr, LiI).

(4) Structure of current collector terminal As shown in FIG. 1, the positive electrode of the laminated electrode body 30 is from one side of the rectangular welded portion 20 of the secondary battery 1 according to the present embodiment and from the short side of one. A part of the positive electrode current collecting terminal 40 and the negative electrode current collecting terminal 50, which are electrically connected to the negative electrode and the negative electrode, respectively, is pulled out. Further, as shown in FIG. 2, the positive electrode current collector terminal 40 is a positive electrode current collector laminated portion 44 extending from the end of the first electrode body unit 32a (that is, a positive electrode active material on the positive electrode current collector). The negative electrode current collector terminal 50 is joined to a bundle of a plurality of exposed positive electrode collectors having no layer formed therein, and the negative electrode current collector terminal 50 is a laminated negative electrode collector extending from the end of the second electrode body unit 32b. It is joined to the portion 54 (that is, a plurality of exposed portions of the negative electrode current collector from which the negative electrode active material layer is not formed on the negative electrode current collector are bundled together). Such joining can be carried out by ultrasonic welding or the like.

Further, as shown in FIG. 1, the positive electrode joining member 42 and the negative electrode joining are joined from the short side on the side opposite to the short side from which the positive electrode current collecting terminal 40 and the negative electrode current collecting terminal 50 are drawn out in the laminated electrode body 30. The member 52 is extended. More specifically, the positive electrode joining member 42 is joined to the positive electrode collector laminated portion (not shown) extending from the end of the second electrode body unit 32b, and the negative electrode joining member 52 is the first. It is joined to a negative electrode current collector laminated portion (not shown) extending from the end portion of the electrode body unit 32a. Then, the positive electrode joining member 42 and the negative electrode joining member 52 are joined via the joining plate 60, so that the first electrode body unit 32a and the second electrode body unit 32b are electrically connected in series. Such joining can be carried out by ultrasonic welding or the like. As the joint plate 60, for example, an aluminum plate or the like can be preferably used, and the thickness of the joint plate can be, for example, about 0.1 mm to 1.0 mm.

As shown in FIG. 2, the technique disclosed here is characterized in that at least a part of the positive electrode current collecting terminal 40 and the negative electrode current collecting terminal 50 are adhered to each other via an insulating layer 70. .. As shown in FIG. 1, the insulating layer 70 may be provided only in a portion where the positive electrode current collecting terminal 40 and the negative electrode current collecting terminal 50 are adhered to each other, or is provided in a state of protruding from such a portion. It may have been. Here, the material constituting the insulating layer 70 is not particularly limited as long as the effects of the techniques disclosed here are not hindered, and for example, a thermosetting resin, a thermoplastic resin, rubber, or the like may be used. can. Examples of the thermosetting resin include epoxy resin, polyurethane resin, polyimide resin and the like. Examples of the thermoplastic resin include acrylic resin, polyolefin resin such as polyethylene resin and polypropylene resin, and polyamide resin. Then, the insulating layer 70 can be adhered to the positive electrode current collecting terminal 40 and the negative electrode current collecting terminal 50 by using an adhesive or the like (for example, the adhesive described below) as appropriate. The material constituting the insulating layer 70 may be an adhesive. The adhesive is not particularly limited as long as the effects of the techniques disclosed herein are not impaired, and for example, an epoxy resin adhesive, an acrylic resin adhesive, an isocyanate adhesive, and a cyanoacrylate adhesive. , Hot melt adhesive (urethane resin, polyamide resin, polyolefin resin) and the like can be used. The thickness of the insulating layer 70 is not particularly limited as long as the effect of the technique disclosed here is not hindered, but may be, for example, about 1 μm to 5 mm (for example, 50 μm to 2 mm or 100 μm to 1 mm). ..

Further, as shown in FIG. 1, in the technique disclosed here, at least one of the positive electrode current collecting terminal 40 and the negative electrode current collecting terminal 50 is pulled out from the positive electrode current collecting terminal and the negative electrode current collecting terminal. It is characterized in that the width orthogonal to the direction in which the electrode is formed is at least half the length in the width direction of the laminated electrode body 30. That is, at _least one of the width _WP in the positive electrode current collector terminal 40 and the width WIN in the negative electrode current collector terminal 50 is at least half of the side length L in the laminated electrode body 30. Here, at least one of the above _- mentioned width _WP and the above-mentioned width WN is preferably 0.55 × L or more and 0.6 × L from the viewpoint of making it difficult for the strength of the current collecting terminal to decrease. Above, 0.65 × L or more, 0.7 × L or more, 0.75 × L or more, 0.8 × L or more, 0.85 × L or more, 0.9 × L or more, 0.95 × L or more (It may be 1.0 × L). Hereinafter, the effects of the techniques disclosed herein will be described with reference to FIGS. 3 and 4.

FIG. 3 is a plan view schematically showing the configuration of the conventional secondary battery 100. Further, FIG. 4 is an explanatory diagram schematically showing the mounting structure of the current collector terminal in FIG. Here, 110, 120, 130, 140, 142, 150, 152, 160 in FIG. 3 and 112, 132a, 132b, 144 in FIG. 4 are 10, 20, 30, 40, 42, 50 in FIG. 1, respectively. It corresponds to 52, 60 and 12, 32a, 32b, 44 in FIG.
As shown in FIGS. 3 and 4, conventionally, when the positive electrode current collecting terminal 140 and the negative electrode current collecting terminal 150 are drawn out from one side of the rectangular welded portion 120 in the exterior body 110, a short circuit is caused by contact between the current collecting terminals. In order to prevent this, there was a tendency to reduce the area of the current collector terminal. As a result, current concentration may occur at the positive electrode current collecting terminal 140 and the negative electrode current collecting terminal 150, or the strength thereof may decrease.
On the other hand, according to the technique disclosed here, when the positive electrode current collecting terminal 40 and the negative electrode current collecting terminal 50 are drawn out from one side of the rectangular welded portion 20 in the exterior body 10, the capacity of the laminated electrode body 30 is relatively large. Even with a large secondary battery 1, the size of the current collector terminal can be secured to be relatively large. This makes it possible to reliably prevent current concentration at the current collector terminal. Further, since the current collector terminals are adhered to each other via the insulating layer 70, the strength thereof is less likely to decrease.

The present invention has been described in detail above, but the above description is merely an example. That is, the techniques disclosed herein include various modifications and changes of the above-mentioned specific examples.

1 Secondary battery 10 Exterior body 12 Accommodation part 20 Welding part 30 Laminated electrode body 32a First electrode body unit 32b Second electrode body unit 40 Positive electrode body unit 40 Positive electrode current collecting terminal 42 Positive electrode bonding member 44 Positive electrode current collecting body laminated part 50 Negative electrode current collecting terminal 52 Negative electrode joining member 54 Negative electrode current collector Laminated part 60 Bonding plate 70 Insulation layer 100 Secondary battery 110 Exterior body 112 Accommodating part 120 Welding part 130 Laminated electrode body 132a First electrode body unit 132b Second electrode body unit 140 Positive electrode current collection Terminal 142 Positive Electrode Bonding Member 144 Positive Electrode Collector Laminated Part 150 Negative Electrode Collector Terminal 152 Negative Electrode Bonding Member 160 Bonding Plate _WP , W _N Width L Side Length

Claims (1)

A laminated electrode body in which a plurality of positive electrodes and negative electrodes are laminated via a separator, and
An exterior body for enclosing the laminated electrode body and
It is a secondary battery equipped with
The exterior body includes an accommodating portion that accommodates the laminated electrode body, and a rectangular welded portion that surrounds the accommodating portion in a sealed state around the accommodating portion.
Have and
A part of the positive electrode current collecting terminal and the negative electrode current collecting terminal electrically connected to the positive electrode and the negative electrode of the laminated electrode body is drawn out from one side of the rectangular welded portion.
Here, at least a part of the positive electrode current collecting terminal and the negative electrode current collecting terminal is adhered to each other via an insulating layer, and at least one of the positive electrode current collecting terminal and the negative electrode current collecting terminal is used. One is a secondary battery, characterized in that the width orthogonal to the drawn direction is at least half the length in the width direction of the laminated electrode body.

Images