JP2000348690A - Cell for battery pack and battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide cells for composing a battery pack which are capable of stably insulating one another for a long time. SOLUTION: This cell is to compose a battery pack by arranging plural cells with designated mutual relation given to them and connecting them, and is equipped with first and second groups of electrodes 10 with mutually different polarities having an electrode active material formed on their collectors of a thin sheet member, a metal container 13 to store the groups of electrodes 10, and a nonaqueous electrolyte filled into the container 13. In this case, the groups of electrodes 10 is stored in the container 10 in a state where they are wrapped in an inner box 9 of a resin having insulating performance and nonaqueous electrolyte resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a unit cell for an assembled battery, particularly to a lithium ion secondary battery, and to the assembled battery.

[0002]

2. Description of the Related Art Lithium-ion secondary batteries have the characteristics of high safety, high energy density and long life. Therefore, small-sized ones have been put to practical use as power sources for portable electric equipment. There is also a demand for large-capacity and large-sized vehicles for use in vehicles and for load leveling (electric load leveling) for storing nighttime electric power. Since electric vehicles and satellites require a high-voltage power supply, even if they have a large capacity and large capacity, a plurality of cells are arranged vertically and horizontally or stacked and connected in series or parallel. Batteries are often used.

[0003] The cells constituting the assembled battery are fixed by adjoining each other with tape, covering the entire assembled battery with a shrinkable tube, or housing it in a resin case. The problem with such a battery pack is that
Multiple cells are close together, and depending on the arrangement and connection method, the potential difference between adjacent cells can reach several hundred volts, causing the risk of temperature rise due to heat generation and short circuit of single cells. It is much larger than when used. Further, when the battery is mounted on a mobile object such as an electric vehicle or an artificial satellite, there is a problem peculiar to the assembled battery that an impact is applied between the batteries in accordance with the acceleration at the time of starting. Therefore, an assembled battery must be designed with due consideration given to the method of cooling the battery and the insulation and impact resistance between the cells.

[0004]

In order to ensure insulation between the cells, it is common to interpose an insulator between the cells. However, in the case of large-capacity, large-sized batteries, the metal container itself that encloses the electrode group itself has a potential, so it is dangerous to add this potential to the potential of the electrode group and then insulate it from the next unit cell. It is. Therefore, an object of the present invention is to provide a unit cell that can stably insulate unit cells constituting a battery pack for a long period of time.

[0005]

In order to achieve the object, a unit cell according to the present invention is a unit cell comprising a plurality of unit cells arranged in a predetermined relationship and connected to each other. A first and a second electrode group having different polarities formed by forming an electrode active material on a current collector formed of a thin planar member, a metal container for housing the electrode group, and a non-filled container. In the unit cell for a battery pack provided with a water electrolyte, the electrode group is housed in a container in a state of being wrapped in an inner box made of an insulating and non-aqueous electrolyte-resistant resin. .

[0006] Since the electrode group is once wrapped in the inner box and housed in the container, the electrode group and the container are insulated. Therefore, the potential of the electrode group and the potential of the container are not added to cause a short circuit with an adjacent unit cell, which is safe. It is also safe to transport cells in a single cell state before constructing the assembled battery.

As the resin constituting the inner box, various resins such as polypropylene and polyethylene terephthalate can be used, and a polyphenylene sulfide (PPS) film is preferable. This resin has mechanical properties comparable to polyester (tensile strength,
This is because they have excellent heat resistance, cold resistance, organic electrolyte solution resistance, flame retardancy, and insulation.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An assembled battery according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a perspective view showing an assembled battery of the embodiment. The assembled battery 11 includes nine cells 12, 12,.
12 are arranged in 3 rows × 3 columns in the plane direction and electrically connected in series.

As shown in a perspective view in FIG. 2, each unit cell 12 is made up of a group of four electrodes 10 wrapped in an inner box 9 made of a resin film and formed in a metal rectangular parallelepiped container 13. This is obtained by injecting the electrolyte solution after being housed and sealed.

As shown in FIG. 3, the electrode group 10 includes a bag-like separator 2 in which a rectangular positive electrode plate 1 is wrapped,
And are alternately overlapped. Each electrode plate 1,
Active material layers 4 and 14 are formed on both surfaces of 3 with a substantially uniform thickness except for one end. Positive electrode plate 1 and negative electrode plate 3
Each end where the active material layers 4 and 14 are not formed is shown in FIG.
The fixed plates 5, 5 and the fixed plates 6, 6 are bundled as shown in FIG.
, And are caulked with the rivets 7 and 8 together with the terminals 15 and 16 after welding to form power generating elements. The number of electrode plates is 30 for the positive electrode plate, 31 for the negative electrode plate, and there is always one more negative electrode plate. The inner box 9 has a thickness of 175
It is made of a crystalline biaxially oriented PPS film having a thickness of μm, and is sold, for example, as Torelina by Toray Industries, Inc.

According to the battery pack of this embodiment, since the electrode group in each battery cell is wrapped in the insulating inner box 9, the container of the battery cell comes into contact with the adjacent container, or the battery pack can be used as a battery pack. It is safe to come in contact with conductors during transport until installation. Moreover, since the resin film constituting the inner box 9 has excellent resistance to organic electrolytic solution, safety is stably maintained for a long time.

[0012]

As described above, according to the present invention, since the cells are insulated by the insulator inside the container except for the regular connection path, they can be used safely as a battery pack. In addition, it can be safely transported for each unit cell.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an assembled battery according to an embodiment.

FIG. 2 is a perspective view showing a method of assembling the cells constituting the assembled battery.

FIG. 3 is a cross-sectional view showing a precursor of each electrode group in a unit cell.

FIG. 4 is a front view showing each electrode group in the unit cell.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 positive electrode plate 2 separator 3 negative electrode plate 4, 14 active material layer 5, 6 fixing plate 7, 8 rivet 9 inner box 10 electrode group 11 assembled battery 12 unit cell 13 container 15, 16 terminals

Claims (3)

[Claims] 1. A unit cell comprising a plurality of unit cells arranged and connected in a predetermined relationship to form an assembled battery, wherein a unit current collector formed of a thin planar member and an electrode active material are formed on each other. In a unit cell for an assembled battery including first and second electrode groups having different polarities, a metal container for housing the electrode group, and a nonaqueous electrolyte filled in the container, the electrode group is insulated. A single cell, wherein the cell is housed in a container in a state of being wrapped in an inner box made of a water-resistant and non-aqueous electrolyte-resistant resin. 2. The unit cell according to claim 1, wherein the resin constituting the inner box is a polyphenylene sulfide film. 3. An assembled battery, comprising a plurality of the cells according to claim 1 arranged and connected in a predetermined relationship.