JP2001351670A - Battery with excellent safety - Google Patents

Abstract

(57) [Problem] To provide a battery excellent in safety in which a minute short-circuit is less likely to occur even in a large battery. A positive electrode plate having a main surface on which a positive electrode active material is formed.
And a negative electrode plate 6 having a main surface on which a negative electrode active material is formed, laminated via a separator 4, and the laminate is housed in a fixed battery case, and the positive electrode plate is used as a positive electrode terminal, and the negative electrode plate is used as a negative electrode terminal. In the battery 1 connected, a pair of metal plates having substantially the same shape as the electrode plate and having no active material formed on at least one main surface are formed on both outer sides of the stacked body with a separator interposed therebetween. Placed so that the main surfaces that are not facing each other,
A battery wherein one of the metal plates is connected to a positive terminal and the other is connected to a negative terminal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery having excellent safety, especially a non-aqueous electrolyte battery having a large capacity, a large size and excellent safety.

[0002]

2. Description of the Related Art Non-aqueous electrolyte batteries, such as lithium ion secondary batteries, are characterized by high safety, high energy density, and long life. Therefore, small batteries are practically used as power sources for portable electric equipment. In addition, large-capacity large-sized ones are also demanded for electric vehicles and for load leveling (leveling of electric power) for storing nighttime electric power.
In order to increase the battery capacity, it is conceivable to design such methods as increasing the thickness of the active material layer or increasing the area without changing the thickness of the active material layer. Since there is a limit, the area of the electrode tends to increase in response to a request for a large capacity.

In general, a lithium ion secondary battery has a positive electrode and a negative electrode, a separator and an electrolyte (usually an organic electrolyte) interposed between the electrodes, and a terminal for accommodating these electric storage elements and having an end face connected to an external circuit. And a container provided with In recent years, a type in which an electrode active material is formed on a current collector made of a metal foil, a laminate of a metal thin film and a resin film, or the like has been used as an electrode for weight reduction. The storage element has a plurality of electrode plates serving as a positive electrode, which are individually placed in the same number of bag-shaped separators, and alternately overlapped with a plurality of electrode plates serving as a negative electrode to form a laminate, and each electrode plate having the same polarity. Are bundled and connected to an external terminal through a strap.

[0004]

However, with the increase in the capacity and the size of the battery, a specific problem different from that of the thin battery arises. That is, in recent years, the storage element itself is light in a thin battery, and a metal resin laminate film is used as a container for storing the storage element. On the other hand, in a large battery, the storage element is still stored in a fixed box-shaped battery case. Must be stored. Moreover, due to the necessity of improving the energy density and the battery life, there is not much room in the inner space of the box with respect to the electricity storage element, but rather, it is housed in the battery case just enough to press the electrode plates together. For this reason, the electrode plate hits the edge or the inner surface of the battery case during storage, and is damaged, or the active material falls off. As a result, the degree of compression of the electrode plate becomes non-uniform in the plane direction, resulting in a short circuit and a risk of resistance heating. Therefore, an object of the present invention is to provide a battery excellent in safety in which a minute short circuit does not easily occur even in a large battery.

[0005]

In order to solve the problem, a battery according to the present invention comprises a positive electrode plate having a main surface formed with a positive electrode active material and a negative electrode plate having a main surface formed with a negative electrode active material. Are laminated via a separator, the laminate is housed in a fixed-shaped battery case, and a positive electrode plate is connected to a positive electrode terminal, and a negative electrode plate is connected to a negative electrode terminal. A pair of metal plates in which the active material is not formed on at least one main surface in substantially the same shape as the above, arranged such that the main surfaces on which the active material is not formed are opposed to each other with the separator interposed therebetween.
One of the metal plates is connected to a positive terminal, and the other is connected to a negative terminal.

As described above, since a pair of metal plates are arranged on both outer sides of the laminate serving as the power storage element, the electrode plate does not hit the battery case when the power storage element is stored in the battery case. Therefore, it is possible to prevent the electrode plate from being damaged and the active material from falling off, and to prevent a minute short circuit. In addition, since the metal plates are always insulated by the separator, there is no problem even if one of the metal plates is connected to the positive terminal and the other is connected to the negative terminal. Then, even when a short circuit occurs unexpectedly due to an external impact, the entire current flows instantaneously without generating resistance heating because there is no active material between the two metal plates. Therefore, the temperature does not become abnormally high.

The metal plate may be the same metal as the current collector of the electrode plate, in other words, a current collector on which no active material is formed. This is because it is not necessary to specially design the metal plate as long as the above-mentioned function is exhibited. Further, each metal plate may be one having no active material formed on both surfaces, or one having an active material formed on one surface and no active material formed on the other surface. This is because the above-described effect is obtained if the surfaces on which the active material is not formed are arranged so as to face each other.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1 A first embodiment of a battery according to the present invention will be described with reference to the drawings. The battery 1 includes, as shown in a cross-sectional view in FIG. 1, a laminate serving as a power storage element 2 and a fixed battery case 3 made of plastic for housing the laminate. As shown in FIG. 2 as an enlarged sectional view of a pair of positive and negative electrodes, the electric storage element 2 has a laminated structure in which a rectangular positive electrode plate 5 is wrapped in a bag-like separator 4 and the negative electrode plate 6 is alternately stacked. Have. Active material layers 7 and 8 are formed on both surfaces of each of the electrode plates 5 and 6 with a substantially uniform thickness except for a not-shown lug located at the upper end. The number of electrode plates is an odd number where the negative electrode plate 6 is one more than the positive electrode plate 5.

In this embodiment, a combination of the positive electrode plate 5, the separator 4 and the negative electrode plate 6, on which no active material layer is formed, is superposed on both outer sides of the electricity storage element 2. Then, together with the electrode plate on which the active material layer is formed and the electrode plate on which the active material layer is not formed, each ear having the same polarity is bundled with a strap and connected to a positive electrode terminal or a negative electrode terminal (not shown). I have.

The active material of the positive electrode plate 5 is a lithium-cobalt composite oxide, which is formed to a predetermined thickness by roll-pressing a current collector made of aluminum foil. The active material of the negative electrode plate 6 is graphite, which is formed to a predetermined thickness by roll-pressing a current collector made of copper foil.

The battery 1 is housed in a battery case 3 with the storage element 2 sandwiched by a combination of electrodes having no active material layer formed thereon, and the ears of the respective electrode plates are bound by a strap for each polarity to form a positive electrode terminal or Connect to the negative terminal, then inject the electrolyte,
Completed by closing. Storage element 2 in battery case 3
When the power storage element 2 is stored in the power storage element 2, the electrode plate in which the active material layer is not formed is protected, so that the electrode plate in the power storage element 2 is not damaged and the active material does not fall off.
Therefore, a local micro short circuit does not occur.

Further, the space between the pair of electrode plates located outside the power storage element 2 is always insulated by the separator 4, so that the battery 1 functions without any trouble. When the battery 1 is shocked and the electrode plates outside the power storage element 2 are short-circuited, there is no active material between them, so that the entire current flows instantaneously. For this reason, there is no fear that the temperature rises abnormally.

Embodiment 2 A battery according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a cross-sectional view showing the battery of the second embodiment. In the battery 10 of this embodiment, contrary to the first embodiment, the number of electrode plates is an odd number in which the number of the positive electrode plates 15 is one more than the number of the negative electrode plates 16. The active material layer 17 is not formed on the outermost positive electrode plate 15. Further, an active material layer 18 is formed on one of the surfaces of the negative electrode plate 16 immediately inside, but the active material layer 18 is not formed on the other surface facing the outer positive electrode plate 15.

Also in the battery 10 of this embodiment, when the storage element 12 is stored in the battery case 13, the storage element 12 is protected by the electrode plate on which the active material layer is not formed. Neither the electrode plate is damaged nor the active material falls off. Therefore, a local micro short circuit does not occur. In addition, the space between the electrode plates located outside the power storage element 12 is always insulated by the separator 14, so that the battery 10 functions without any trouble. Then, when the battery 10 receives an impact and the electrode plates outside the power storage element 12 are short-circuited, there is no active material between them, so that the entire current flows instantaneously. For this reason, there is no fear that the temperature rises abnormally.

[0015]

As described above, according to the present invention, a micro short circuit is unlikely to occur during use of a battery, and almost no heat is generated even if a short circuit occurs unexpectedly. Therefore, the present invention is safe.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a battery according to a first embodiment.

FIG. 2 is an enlarged sectional view showing a pair of electrodes of the battery.

FIG. 3 is a cross-sectional view illustrating a battery according to a second embodiment.

[Explanation of symbols]

 1, 10 Battery 2, 12 Storage element 3, 13 Battery case 4, 14 Separator 5, 15 Positive electrode plate 6, 16 Negative electrode plate 7, 8, 17, 18 Active material layer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H022 AA09 BB03 CC04 CC12 CC24 EE01 5H024 AA01 AA02 CC07 DD11 5H028 AA01 CC08 CC20 CC24 EE01 5H029 AJ12 AK03 AL07 AM01 BJ02 BJ12 DJ02 DJ05 DJ07 EJ01 HJ12

Claims (1)

[Claims] A positive electrode plate having a positive electrode active material formed on a main surface thereof;
A negative electrode plate having a negative electrode active material formed on its main surface is laminated via a separator, the laminate is housed in a fixed battery case, and the positive electrode plate is connected to the positive electrode terminal, and the negative electrode plate is connected to the negative electrode terminal. In the battery, a pair of metal plates having substantially the same shape as the electrode plate and having no active material formed on at least one main surface are formed on both outer sides of the laminate, and a main surface on which no active material is formed with a separator interposed therebetween. A battery characterized in that they are arranged so as to face each other, and one of the metal plates is connected to a positive terminal and the other is connected to a negative terminal.