JP2003272588A - Battery module - Google Patents

Abstract

(57) [Problem] To provide a battery module capable of preventing vibration during normal use from being transmitted to a battery and reliably releasing gas to an external space when gas is generated from a laminated battery. SOLUTION: A laminate film which is a battery exterior,
A power generating element comprising at least an electrode, an active material, and an electrolyte;
A battery module comprising: a battery in which the power generation element is covered with the laminate film; a battery assembly in which a plurality of the batteries are assembled; and a case for housing the battery polymer, wherein the battery or the battery assembly is provided. A plurality of fillers composed of materials having different characteristics were provided between the body and the case, and a filler having the lowest flow start temperature among the plurality of fillers was arranged around the battery exterior.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a structure in which a battery element is housed and sealed by using a polymer-metal composite laminate film for the battery exterior and bonding the peripheral portion thereof by heat fusion. The present invention relates to a module structure using a battery included therein.

[0002]

2. Description of the Related Art Conventionally, metal cans have been mainly used for the exterior of batteries, but in recent years, application examples in which it is necessary to suppress the weight increase, such as mobile phones and notebook computers, have dramatically increased. A so-called laminated battery in which battery elements such as electrodes, active materials, and electrolytes are hermetically sealed by using a relatively lightweight laminated film having a degree of freedom in shape as an exterior has started to be adopted. Since the laminate film is flexible, the laminate battery is usually fixed to a case formed of resin, metal or the like and used as a battery module. Further, when a plurality of unit cells are installed in one module, they are generally installed in contact with each other without any gap in order to improve volume efficiency.

In such a laminated battery, when an abnormal operation such as overcharging is performed, for example, in a secondary battery using lithium ion as a power generating substance, the electrolyte is decomposed to generate carbon dioxide gas, ethylene gas, or the like. Occurs and causes the laminate film on the exterior of the battery to expand. As mentioned above, the laminated battery is generally installed in the module without any gap,
Expansion of the battery is hindered, which may result in rupture of the case, sudden ejection of gas or electrolyte, and the like. To address this, as a conventional technique, for example, Japanese Patent Laid-Open No. 2001-256
There has been a method in which a groove-shaped guide portion is provided on the inner surface of the case as in the example shown in 941 and the expansion space is secured by being disengaged from the guide portion when the battery expands.

[0004]

However, in the method of installing the unit cell in the groove-shaped guide portion as in the above-mentioned prior art, the unit cell is easily detached from the guide portion, so that the vibration of a portable device, an automobile, etc. In the case of repeated use, even during normal use, the unit cell may disengage from the guide part due to vibration, and the tab may break due to large movement in the case, or the laminate may be damaged due to friction between the battery and the case, and in the worst case wear The electrolyte may leak out. Further, there is a problem that if the case is hermetically closed at the time of gas ejection, the case may eventually be filled with gas, and the gas may suddenly eject from the case.

The present invention has been made in view of the problems of the prior art as described above, prevents the vibration during normal use from being transmitted to the battery, and reliably releases the gas when the laminated battery generates the gas. An object is to provide a battery module that can be released to the external space.

[0006]

As a result of intensive studies in view of the above problems, as a result, a laminate film as a battery exterior, a power generating element including at least an electrode, an active material and an electrolyte, and a battery in which the power generating element is covered with the laminate film are provided. And a battery assembly in which a plurality of the batteries are assembled, and a case accommodating the battery polymer, the battery module having different characteristics between the battery or the battery assembly and the case. It has been found that the above object can be achieved by providing a plurality of fillers made of materials and arranging the filler having the lowest flow starting temperature among the plurality of fillers around the battery exterior. .

[0007]

In the present invention, since the filler is provided between the battery and the case, external vibration does not propagate to the battery during normal use. Furthermore, even if the gas expands due to gas generation inside the battery, the expansion space is secured by the flow of the filler having the lowest flow start temperature around the battery exterior, and the gas is reliably discharged from the periphery of the battery exterior to the external space. can do.

This battery module is used as a power source for electric vehicles, hybrid vehicles, fuel cell vehicles, or as a 12V, 42V battery for automobiles, and thus has high reliability for electric vehicles, hybrid vehicles, fuel cell vehicles, and general vehicles. Can provide a car.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the battery module of the present invention will be described below, but the present invention is not limited to these embodiments.

(Embodiment 1) As a first embodiment of the battery module according to the present invention, an external view of the battery module is shown in FIG.
2 is a sectional view showing the internal structure of the laminated battery 5 when a lithium ion secondary battery is used. FIG. 2 is a diagram showing a vertical cross section taken along the line AA in FIG.

The lithium ion secondary battery has positive and negative electrodes, positive and negative electrode active materials, a separator,
It consists of electrolytes. For example, a base material containing aluminum as the main component is preferably used as the positive electrode material, and a base material containing copper or nickel as the main component is preferably used as the negative electrode material.
The positive electrode active material formed on the surface of the positive electrode substrate includes lithium manganate (LiMn ₂ O ₄ ) and lithium cobalt oxide (LiCn).
A material in which carbon powder such as acetylene black or graphite powder is mixed with a positive electrode active material of a lithium transition metal compound such as oO ₂ ) or lithium nickel oxide (LiNiO ₂ ) to improve conductivity is preferably used.

The negative electrode active material formed on the surface of the negative electrode base material is composed of an amorphous carbonaceous material such as soft carbon or hard carbon or a negative electrode active material powder such as carbonaceous powder such as natural graphite. In particular, the diffusion of lithium ions in the crystal is easy, the specific gravity is large,
It is preferable to use a highly graphitized carbon material such as graphite or artificial graphite that has a large proportion of lithium ions that contribute to charge / discharge per unit weight.

As the separator, a film having a three-layer structure in which a lithium ion permeable polyethylene film having micropores is sandwiched between porous lithium ion permeable polypropylene films is preferable. When such a separator is used, an electrolytic solution as a lithium ion conductor is required, and as this electrolytic solution, L
An iPF6 electrolyte dissolved in ethylene carbonate (hereinafter referred to as EC), diethyl carbonate (hereinafter referred to as DEC), propylene carbonate (hereinafter referred to as PC), ethyl methyl carbonate (hereinafter referred to as EMC), or a mixed solution thereof. Etc. are preferably used.

The lithium-ion secondary battery, which is the laminated battery 5 in this embodiment, is obtained by appropriately combining the above-mentioned battery components, enclosing the same with the electrolytic solution in the outer laminate, and connecting the end 5'to the electrode terminal (shown in the figure). No) is derived to the outside. The electrode terminals are connected to a terminal 6 provided in the battery case 1 for taking out an electric current.

In the first embodiment, the first filling material 3 for supporting most of the laminated battery 5 except the end 5'to keep it stationary, and the second filler 3 arranged in contact with the end of the laminated battery 5 are provided.
The laminated battery 5 is held by the case 1 including the filling material 4 and the through hole 2 in which the second filling material 4 communicates with the outside.

Here, for example, a mixed solution of PC and EMC is used as an electrolytic solution, an acrylic potting material having a flow starting temperature of 140 ° C. is used as the first filling material 3, and a second filling material 4 is used as the second filling material 4. An epoxy-based potting material having a flow starting temperature of 110 ° C. is used. The flow start temperature is the temperature at which the resin material softens and flows when the temperature is raised, and is also called the flow temperature or flow temperature.
It is measured using a curable flow tester or the like.

Next, the operation of the first embodiment will be described.
If an abnormality occurs in the laminated battery 5 for some reason and the temperature rises, the temperature inside the battery is EM, which is the electrolyte.
When the boiling point of C reaches around 110 ° C., gas is generated and the battery 5 expands. At that time, the first filler 3 maintains its shape because it is below the flow start temperature, but the second filler 4 reaches the flow start temperature and flows. Therefore, the portion of the filling material 4 becomes a space filled with the fluid, and the fixing pressure of the laminating portion fixed by the filling material 4 decreases, so that the gas concentrates on the end portion 5 ′ of the battery. After that, the battery end portion 5 ′ is broken by the pressure of the generated gas and the gas is led out, and the gas generated from the inside of the battery is guided to the outside of the case 1 through the through hole 2.

At this time, since it is necessary to hold the battery by maintaining the shape of the first filling material 3, it is desirable that the second filling material 4 does not flow to a temperature sufficiently higher than the flowing temperature. Considering the possibility of uneven temperature distribution, it is necessary to use a combination of fillers having a difference in flow initiation temperature of at least 20 ° C or higher, preferably 30 ° C or higher.

When the electrolyte reaches the boiling point and the gas is discharged to the outside of the battery, the second filling material 4 around the electrolyte must flow to guide the gas to the outside of the case 1.
The difference between the boiling point of the electrolyte and the flow starting temperature of the second filler 4 is preferably as small as possible, and it is necessary that the difference is within 20 ° C. at most.

(Embodiment 2) FIG. 3 is an external view of a battery module showing a second embodiment of the present invention. The second embodiment is the same as the second filling material 4 in the first embodiment of the battery case 1.
Is a mesh-like member 7 instead of a simple hole.

For this reason, even if the second filling material 4 starts to flow, it does not easily come off from the battery case 1, and the environment outside the battery module is not adversely affected. Further, the gas generated from the laminated battery 5 can easily pass through between the meshes of the mesh member 7, so that the gas can be discharged from the battery module.

(Embodiment 3) FIG. 4 is a sectional view showing a third embodiment of the present invention. In the third embodiment, the second filler 4
The contact surface between the first filling material 3 and the vicinity 2a of the through hole
Is smoothly formed into a curved surface.

As a result, the gas can be discharged to the outside of the battery case 1 more reliably. (Other Embodiments) The respective embodiments have been described above.
The present invention is not limited to this configuration, and for example, a protrusion for breaking the laminate exterior may be provided inside the battery case, and a filler having the lowest flow starting temperature may be arranged around the protrusion. As a result, the laminated battery 5
When an abnormality occurs inside and the temperature rises, the filling material around the protrusions flows to provide an expansion space. The gas generated in this expansion space is induced to expand the laminate exterior. The gas may be led out to the outside of the battery case by breaking this expanded laminate exterior by the protrusion.

[Brief description of drawings]

FIG. 1 is a perspective view illustrating an appearance of a battery module according to a first exemplary embodiment.

FIG. 2 is a cross-sectional view taken along the line AA of the battery module of Example 1.

FIG. 3 is a perspective view showing an appearance of a battery module of Example 2.

FIG. 4 is a sectional view of the battery module of Example 3 taken along the line AA.

[Explanation of symbols]

1 battery case 2 through holes 3 First filler 4 Second filler 5 Laminated battery 5'end 6 terminals 7 Mesh members

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Osamu Shimamura             Nissan, Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan             Inside the automobile corporation (72) Inventor Hideaki Horie             Nissan, Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan             Inside the automobile corporation F term (reference) 5H011 AA00 BB03 CC02 CC08 FF03                       GG01 KK04                 5H012 AA03 BB01 BB08 CC00 FF08                       GG01 JJ10                 5H040 AA33 AT04 AY06 NN00

Claims (8)

[Claims] 1. A laminate film as a battery exterior,
A power generation element comprising at least an electrode, an active material and an electrolyte,
A battery module comprising: a battery in which the power generating element is covered with the laminate film; a battery assembly in which a plurality of the batteries are assembled; and a case in which the battery polymer is housed, the battery or the battery assembly A plurality of fillers made of materials having different characteristics are provided between the body and the case, and the filler having the lowest flow start temperature among the plurality of fillers is arranged around the battery exterior. A battery module characterized by. 2. The battery module according to claim 1, wherein the battery has a battery exterior joint portion in which a part or all of an outer peripheral portion of a power generation element is covered with the laminate film by heat fusion to be housed / sealed. From the plurality of fillers around the battery exterior joint part,
A battery module comprising a filler having a lowest flow starting temperature. 3. The battery module according to claim 1, wherein the difference between the flow start temperature of the filler having the lowest flow start temperature and the flow start temperature of the other filler is at least 20.
A battery module having a temperature of ℃ or higher. 4. The battery module according to claim 1, wherein the difference between the flow starting temperature of the filler having the lowest flow starting temperature and the boiling point of the electrolyte of the battery is within 20 ° C. A battery module characterized in that 5. The battery module according to claim 1, wherein the filler having the lowest flow starting temperature is provided with a filler communicating portion that communicates with an outermost portion of the other filler. A battery module characterized by the above. 6. The battery module according to claim 5, wherein a through hole that communicates the inside and the outside of the case is provided in a part of the case, and the filler communicating portion and the through hole are communicated with each other. Battery module. 7. The battery module according to claim 5, wherein the through hole is provided with a mesh member through which at least gas can flow at a boundary between the outside of the case and the inside of the case. . 8. The battery module according to claim 1, wherein a contact surface between the filler having the lowest flow starting temperature and the other filler, and the vicinity of the through hole. A battery module having a curved surface.