WO2012036153A1

WO2012036153A1 - Secondary cell

Info

Publication number: WO2012036153A1
Application number: PCT/JP2011/070852
Authority: WO
Inventors: 梶谷　浩司
Original assignee: 日本電気株式会社
Priority date: 2010-09-17
Filing date: 2011-09-13
Publication date: 2012-03-22
Also published as: JP6003647B2; JPWO2012036153A1

Abstract

In the disclosed secondary cell, a casing formed from a laminate film houses an electrolyte and a laminate comprising a positive electrode, a separator and a negative electrode. Terminals connected to each electrode protrude from the casing for extracting power to the outside. Columnar holding members are provided between the casing and both sides of the laminated electrodes and separator on both sides where there are no terminals.

Description

Secondary battery

The present invention relates to a laminate type secondary battery, and particularly to its mounting.

In recent years, environmental power generation (solar power, wind power, geothermal heat, tide, etc.) has attracted attention as one of the measures to reduce carbon dioxide emissions, which are a cause of global warming. These power generation methods are still more expensive than oil and nuclear power generation, but are excellent in terms of safety and cleanliness. In addition, if electric power energy generation / storage networks such as smart grids are networked, and electric power consumption control and efficient usage methods are established throughout society, it will be easy to introduce electric vehicles and the like. As a result, carbon dioxide emissions are further reduced, and the emergence of an environmentally friendly society is expected.

However, in the energy harvesting method, since the amount of power generation varies according to changes in the natural environment, it is almost impossible to provide a stable power supply alone. In particular, solar power generation cannot generate power at night, and when sunlight is blocked by clouds even in the daytime, the amount of power generation is significantly reduced.
As a means to suppress such fluctuations in the amount of power generation, simply discard the fluctuations in the amount of power generation as heat, or use the fluctuations in the amount of power generation as a power source for pumping up water (lifting water from the ground for hydropower generation). Use is under consideration. Recently, a large-scale secondary battery is used to charge the fluctuations in the amount of power generation. For secondary batteries for such applications, lead storage batteries and sodium-sulfur batteries are often used because reliability and low cost are required preferentially. However, relatively small power generation systems (such as solar power generation for personal use) require miniaturization as much as possible as a whole system, so nickel hydride secondary batteries and lithium ion secondary batteries are often used. It has become.

On the other hand, in a secondary battery mounted on a movable object such as an electric vehicle or a robot, it is an important factor that the electric capacity is large and the weight is light. For this reason, a nickel-hydrogen secondary battery or a lithium ion secondary battery tends to be used as a secondary battery mounted on a movable object.
Secondary batteries mounted on movable objects are required to be lightweight and have high output. For this reason, since it is necessary to reduce the weight as much as possible except for the main components (positive electrode, negative electrode, separator, electrolyte solution, etc.) constituting the battery, a laminate film is used as an exterior body particularly in a lithium ion secondary battery. There is a tendency. This laminate film has a three-layer structure of polypropylene / aluminum thin film / nylon. The polypropylene part is sealed by heat-sealing so that the electrolyte does not leak outside. In addition, by providing an aluminum thin film in the film, it is possible to prevent moisture from entering from the outside and to suppress denaturation of the electrolytic solution. Thus, by using the laminate film, the secondary battery is laminated by packing the constituent members of the secondary battery including the positive electrode, the negative electrode, the separator, the electrolytic solution, and the metal terminal for power extraction connected to each electrode. Is formed.

For example, as disclosed in Patent Document 1, a conventional laminate-side secondary battery surrounds the entire periphery of a laminate composed of a positive electrode, a negative electrode, and a separator with a reinforcing frame, and the frame is laminated with a laminate film. It is constituted by covering with.
Further, as disclosed in Patent Document 2, a laminate type secondary battery in which the reinforcing frame is not provided is also known. It is advantageous to reduce the size and weight when the reinforcing frame is not provided.

JP 2006-179442 A JP-A-8-203532

The structure of a conventional laminated secondary battery without a reinforcing frame will be described with reference to FIGS. In the secondary battery 50, a positive electrode 52, a separator 53, and a negative electrode 54 are stacked and accommodated in an exterior body 51 made of a laminate film, and an electrolytic solution 56 is accommodated. Further, a positive electrode terminal 57 connected to the positive electrode 52 and a negative electrode terminal 58 connected to the negative electrode 53 protrude from the exterior body 51 to the outside. Hereinafter, the

terminals

57 and 58 will be described unless it is necessary to distinguish between them. A seal member 59 is provided at a portion where the terminal 57 and the terminal 58 protrude from the exterior body 51.

In the actual manufacturing process of the secondary battery 50, first, the positive electrode 52, the separator 53, and the negative electrode 54 are sequentially laminated. And the electrode laminated body 55 which welded the electrode which laminated | stacked the positive electrode 52 and the negative electrode 54, respectively, and the terminal 57 and the terminal 58 is formed. If each component is not accurately positioned, it may cause variations in battery capacity and occurrence of defects (internal short circuit or seal failure). Thereafter, the laminate film is positioned on both surfaces of the electrode laminate 55 with respect to the electrode laminate 55 with a jig or the like. In the laminate film, heat sealing (thermal fusion) is performed on the side 61 on the side where the

terminals

57 and 58 protrude and the left and

right sides

62 and 63 connected to the side 61. There is no restriction | limiting in particular about the order of the seal | sticker in a edge | side, and it is also possible for three sides simultaneously. Thereafter, one side (lower side in FIG. 8) 60 of the opened laminate film is directed upward, and the electrolytic solution 56 is injected therefrom. Then, this is decompressed, the inside air is exhausted, the permeability of the electrolyte solution 56 to the electrode material is increased, and one side of the laminate film opened in the reduced pressure state (ie, side 60) is heat-sealed. The secondary battery 50 is completed in a state where pressure is applied to the laminate film. FIG. 10 is a bottom view as viewed from the opened side 60 side. FIG. 11 is a diagram showing a cross-sectional structure of the secondary battery 50 in which two sets of the positive electrode 52 and the negative electrode 54 are stacked.

In the secondary battery 50 configured as described above, when the terminal 57 and the terminal 58 are connected to an external electric circuit, the stacked positive electrode 52 and negative electrode 54 have a cantilever structure. When a lateral external force is applied to the electrode 54 in FIG. 8, the electrode 52 and the electrode 54 may be relatively displaced in the in-plane direction as shown in FIG. At this time, since the opposing area between the electrode 52 and the electrode 54 decreases, the battery capacity decreases. Further, when an external force is further applied, the

electrodes

52 and 54 are detached and a scratch mark on the separator 53 is generated, which may cause an internal short circuit. In addition, there are cases where the thin (several hundred microns) electrode 52 and the electrode 54 come into contact with the outer package 51 made of a laminate film, and the outer package 51 may be damaged.
13 and 14 show a structure in which the lead-out direction of the terminal of the positive electrode 52 and the lead-out direction of the terminal of the negative electrode 54 are opposite to each other. Again, the possibility of relative displacement of electrode 52 and electrode 54 remains.
An object of the present invention is to provide a laminate type secondary battery having excellent vibration and impact resistance.

The present invention employs the following means in order to solve the above problems.
That is, in the secondary battery of the present invention, the positive electrode, the separator, and the negative electrode are stacked inside the exterior body formed of the laminate film, and the electrolytic solution is accommodated. In the secondary battery in which the terminal protrudes from the exterior body, each of the stacked electrodes and the separator is provided with a columnar holding member between both sides where the terminal does not exist and the exterior body. To do.

According to the present invention, even when a lateral external force is applied to the terminal, since the columnar holding members are installed between the both sides of the positive electrode and the negative electrode and the exterior body, displacement of the positive electrode and the negative electrode is prevented. Vibration resistance performance can be improved.

It is a front view of the secondary battery in the 1st Embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line AA in FIG. It is the bottom view which looked at the secondary battery of 1st Embodiment before electrolyte solution injection | pouring from the Y direction of FIG. It is an external appearance perspective view of the holding member used in the secondary battery of 1st Embodiment. It is a front view of the modification of the secondary battery in the 1st Embodiment of this invention. It is an external appearance perspective view of the holding member used in the secondary battery of the 2nd Embodiment of this invention. It is an external appearance perspective view of another holding member used in the secondary battery of the 2nd Embodiment of this invention. It is a front view of the conventional secondary battery. FIG. 9 is a sectional view taken along line BB in FIG. It is the bottom view which looked at the conventional secondary battery before electrolyte solution injection | pouring from the X direction of FIG. It is sectional drawing of the conventional secondary battery provided with multiple positive electrodes and negative electrodes. It is a figure for demonstrating the shift | offset | difference of a positive electrode and a negative electrode in the conventional secondary battery. It is a front view of another conventional secondary battery. It is CC sectional drawing of FIG.

Hereinafter, embodiments of a secondary battery according to the present invention will be described with reference to FIGS. 1 to 7.
First, a first embodiment of a secondary battery according to the present invention will be described with reference to FIGS. 1 to 5.
The secondary battery 1 includes a rectangular bag-shaped outer package 2 made of a laminate film, and an electrode stack 6 in which a positive electrode 3, a separator 4, and a negative electrode 5 are stacked inside the outer package 2, and an electrode Two holding members 7 arranged on the left and right sides of the laminate 6 and the electrolyte 8 are accommodated. The electrode 3 and the electrode 5 are connected to a terminal 9 and a terminal 10 for extracting electric power to the outside, respectively. More specifically, a positive electrode terminal 9 is connected to the positive electrode 3, and a negative electrode terminal 10 is connected to the negative electrode 5. Hereinafter, the

terminals

9 and 10 are referred to unless specifically distinguished. These

terminals

9 and 10 protrude outward from the side 2a of the exterior body 2. The positive electrode terminal 9 and the negative electrode terminal 10 are spaced apart from each other on the one side 2 a of the exterior body 2. Then, the four

sides

2a, 2b, 2c and 2d of the outer peripheral portion of the exterior body 2 are joined and sealed, and a seal member 11 is provided at a portion where the

terminals

9 and 10 protrude from the exterior body 2.

In FIG. 2, for convenience of illustration, the laminate film constituting the exterior body 2 is shown as a single layer, but in actuality, it is composed of three layers of polypropylene / aluminum thin film / nylon. The exterior body 2 is sealed so that the electrolyte solution 8 does not leak to the outside by heat-sealing the polypropylene portion of the innermost layer. The aluminum thin film prevents moisture from entering from the outside and suppresses denaturation of the electrolyte solution 8.

One holding member 7 is provided between the left side of the electrode laminate 6 and the inner surface of the left side 2b of the outer package 2, and between the right side of the electrode laminate 6 and the inner surface of the right side 2c of the outer package 2. It is arranged one by one.
As shown in FIGS. 3 and 4, the holding member 7 has a triangular prism shape, and one of the three

side surfaces

7 a, 7 b, and 7 c of the holding member 7 is the left side or the right side of the electrode stack 6. The remaining two

side surfaces

7b and 7c are disposed along the inner surface of the exterior body 2 that is continuous with the left side 2b or the right side 2c. That is, the left and right side surfaces of the positive electrode 3 and the negative electrode 5 are in contact with the side surfaces 7 a of the left and right holding members 7. Thus, since the side surface 7a of the holding member 7 is in contact with the positive electrode 3 and the negative electrode 5, at least the side surface 7a needs to be insulative. Therefore, the holding member 7 is formed of an insulating material, or at least the side surface 7a is covered with an insulating material. Of course, the entire surface of the holding member 7 may be covered with an insulating material. The holding member 7 has such a length that its upper and lower ends slightly protrude upward and downward from the electrode laminate 6.

The secondary battery 1 is manufactured as follows. First, the electrode stack 6 is formed by sequentially stacking the positive electrode 3 including the positive electrode terminal 9, the separator 4, and the negative electrode 5 including the negative electrode terminal 10. At this time, by accurately positioning each component, it is possible to prevent variations in battery capacity and assembly failure (internal short circuit or seal failure). Then, the holding member 7 is placed in contact with both side portions of the electrode laminate 6. After that, on both the front and back sides, a laminate film, which is a material of the exterior body 2, is positioned with a jig or the like, and placed on the side 2a, the left side 2b, and the right side 2c on the side where the

terminals

9 and 10 protrude in the laminate film. On the other hand, heat sealing (heat fusion) is performed. There is no particular limitation on the order of sealing these three sides, and it is possible to use three sides simultaneously. Then, the side 2d side opened in the laminate film is positioned upward, and the electrolytic solution 8 is injected from the opening. Thereafter, the pressure was reduced and the air inside was removed, the permeability of the electrolyte solution 8 to the electrode material was increased, and the side 2d opened in a reduced pressure state was thermally fused, thereby applying pressure in the laminate film. In this state, the secondary battery 1 is completed.

In the secondary battery 1 configured as described above, the electrode laminate 6 is also applied when a lateral external force is applied to the

terminals

9 and 10 when the

terminals

9 and 10 are connected to an external electric circuit. Since the holding member 7 is installed on both the left and right sides of the first electrode 3 and the holding member 7 is in contact with the side surfaces of the positive electrode 3 and the negative electrode 5, the displacement of the positive electrode 3 and the negative electrode 5 can be prevented. Therefore, the relative displacement between the electrode 3 and the electrode 5 of the electrode stack 6 can be significantly suppressed against vibration shock, and vibration shock resistance is improved. As a result, it is possible to reliably prevent a decrease in battery capacity, electrode detachment, and internal short circuit that have conventionally occurred due to electrode displacement.
Further, the reliability of the secondary battery 1 when the secondary battery 1 is mounted on a movable object (for example, a vehicle) is improved.
Moreover, since the cross-sectional shape of the holding member 7 is a triangle, the stress applied to the laminate film can be reduced, and the life of the secondary battery 1 can be extended.

In addition, as shown in FIG. 5, the relative movement of the holding member 7 can be suppressed by adding the connecting member 12 that connects the lower ends of the left and right holding members 7, and further the vibration resistance performance is improved. It becomes possible to make it.

Next, a second embodiment of the secondary battery according to the present invention will be described with reference to FIGS.
The secondary battery 1 of the second embodiment is different from the secondary battery 1 of the first embodiment described above in the structure of the holding member 7, and the other points are the secondary battery of the first embodiment. Same as battery 1. Therefore, about the whole structure, drawing of FIGS. 1-3 is used, and description is abbreviate | omitted.

FIG. 6 is an external perspective view of the holding member 7 in the secondary battery 1 of the second embodiment, and corresponds to FIG. 4 in the first embodiment.
The holding member 7 is hollow inside. One end 13 in the longitudinal direction of the holding member 7 is closed, and the other end 14 is open. One closed end portion (hereinafter referred to as a closed end portion) 13 of the holding member 7 is disposed on the side 2 a side in the exterior body 2. The other open end (hereinafter referred to as an open end) 14 is arranged on the side 2d side in the exterior body 2. That is, it arrange | positions at the side used as an open port, when inject | pouring the electrolyte solution 8. FIG. A plurality of circular holes 15 are provided on the side surface 7a of the holding member 7 that contacts the side portion of the electrode laminate 6 at predetermined intervals on a straight line in the longitudinal direction, and are continuous with the internal cavity. The holding member 7 is also formed of an insulating member, or at least the side surface 7a is covered with an insulating material.

In the secondary battery 1 of the second embodiment, the holding member 7 has a function as an injection tube when injecting the electrolytic solution 8 in addition to the function of preventing the displacement of the

electrodes

3 and 5.
In the second embodiment, in the manufacturing process of the secondary battery 1, after the holding members 7 are placed in contact with both side portions of the electrode laminate 6, the laminate as the material of the exterior body 2 is formed on both the front and back sides. The film is positioned by positioning with a jig or the like. Further, after heat sealing is performed on the side 2a, the left side 2b, and the right side 2c on the side where the terminal 9 and the end portion 10 protrude in the laminated film, the side 2d side opened in the laminated film is positioned upward. The steps so far are the same as the manufacturing steps in the first embodiment.

Thereafter, when the electrolyte solution 8 is injected, it is not injected from the opening of the side 2d of the laminate film as in the case of the first embodiment, but inside the holding member 7 from the opening end portions 14 of both holding members 7. The electrolytic solution 8 is injected into. The electrolytic solution 8 injected into the holding member 7 is discharged from the hole 15 of the holding member 7 into the laminate film. When the electrolytic solution is injected from the hole 15 of the holding member 7 in this way, the electrolytic solution 8 is injected from both side surfaces of the electrode laminate 6. As a result, since the penetration distance of the electrolyte into the electrode material is reduced as compared with the case where the electrolyte is injected from one direction, the time required for the electrolyte injection step can be reduced. In particular, the number of stacked layers is large, and the time required for the electrolyte injection process of a large-area laminated secondary battery can be greatly reduced.

Also, the electrolyte solution 8 can be improved in permeability to the electrode material by injecting the electrolyte solution 8 from one holding member 7 and exhausting air from the other holding member 7. It is possible to shorten the time of the injection process. However, in this case, an injection pipe (not shown) connected to one holding member 7 and an exhaust pipe (not shown) connected to the other holding member 7 are projected from the opening of the side 2d of the laminate film and opened. Close the mouth.
As described above, since the time of the electrolyte injection process can be shortened, the productivity is improved, the yield is improved, and as a result, the cost can be reduced.

FIG. 7 shows a mode in which a movable body 20 that is movable relative to the holding member 7 in the longitudinal direction is provided on the side surface 7 a of the holding member 7 having the holes 15. The movable body 20 has a size capable of closing all the holes 15, and when the movable body 20 is slid from the position shown in FIG. 7 to the opening end 14 side of the holding member 7, the closed end of the holding member 7. The holes can be sequentially opened from the hole 15 on the side close to the portion 13. That is, the hole 15 can be opened and closed by sliding the movable body 20, whereby the injection position of the electrolytic solution 8 can be changed. Then, by appropriately selecting the injection position, the electrolyte solution 8 can be efficiently infiltrated into the electrode material, and further, the air can be efficiently discharged, so that the time of the electrolyte injection process As a result, the cost can be reduced.

Although the present invention has been described with reference to the above embodiment, the present invention is not limited to the configuration of the above embodiment, and various modifications that can be made by those skilled in the art within the scope of the present invention. Of course, including modifications.
For example, in the above embodiment, the secondary battery including one positive electrode 3 and one negative electrode 5 has been described, but the present invention is applied to a secondary battery in which a number of positive electrodes, separators, and negative electrodes are stacked as shown in FIG. The invention can also be applied. Further, the present invention can be applied to a secondary battery in which the positive electrode terminal drawing direction and the negative electrode terminal drawing direction are opposite to each other as shown in FIG.
The holding member 7 may have a substantially triangular cross-sectional shape. For example, the corners of the triangle may be rounded with a rounded shape, or the side surface 7b and the side surface 7c may be formed with curved surfaces that curve outward. .
This application claims priority based on Japanese Patent Application No. 2010-209041 filed in Japan on September 17, 2010, the contents of which are incorporated herein by reference.

Provide laminate type secondary batteries with excellent vibration and shock resistance.

DESCRIPTION OF SYMBOLS 1 Secondary battery 2 Exterior body 3 Positive electrode 4 Separator 5 Negative electrode 6 Electrode laminated body 7 Holding member 8 Electrolytic solution 9 Positive electrode terminal 10 Negative electrode terminal 12 Connecting member 15 Hole 20 Movable body

Claims

A positive electrode, a separator, and a negative electrode are stacked inside an exterior body formed of a laminate film, and an electrolytic solution is accommodated. A terminal connected to each of the electrodes and for taking out electric power protrudes from the exterior body. In secondary batteries,
A secondary battery comprising columnar holding members between both sides of the stacked electrodes and separator where the terminals do not exist and the exterior body.
The secondary battery according to claim 1, wherein the holding member is made of an insulating material or is covered with an insulating material.
The said holding member has a cavity at the time of inject | pouring the said electrolyte solution into the said exterior body, The hole is provided in the surface facing each said electrode in the said holding member. Item 4. The secondary battery according to Item 2.
The secondary battery according to claim 3, wherein the holding member includes a movable body that can move relative to the holding member and close the hole.
The secondary battery according to any one of claims 1 to 4, further comprising a connecting member that connects the two holding members.
The secondary battery according to any one of claims 1 to 5, wherein the holding member has a substantially triangular cross-sectional shape.