JP2012033464A - Battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable battery pack in which thermal chain of unit cells in the battery pack is prevented, an appropriate safety measure is taken, and good shock resistance is exhibited normally, and to provide a battery pack in which damage on the exterior case is prevented by ensuring an appropriate gap between unit cells, and reduction in production cost can be expected.SOLUTION: In a core component 4 of a battery pack 1, a resin core 60 having a curved surface portion corresponding to the side surface shape of a unit cell is arranged between adjoining unit cells with mica sheet bodies 61a and 61b interposed therebetween. The core normally holds the unit cell appropriately and imparts rigidity to the battery pack. During abnormal heating of the unit cell, the sheet bodies 61a and 61b exhibit heat insulation effect, thermally deform the core while preventing excessive fusion of the core, and form air layers 602a and 602b between the core and the sheet bodies 61a and 61b thus attaining heat insulation effect.

Description

  The present invention relates to a battery pack including a plurality of unit cells, and more particularly to an improved technique for preventing a thermal chain of unit cells and reducing production costs.

In recent years, a battery pack in which a secondary battery that can be repeatedly charged and stored in a case is widely used. Pack batteries are widely used as main power sources or backup power sources for notebook personal computers (notebook PCs), mobile phones, PDAs, and other various electronic devices.
A typical battery pack has a configuration in which a plurality of cylindrical lithium ion batteries, which are unit cells, are connected and electrically connected to a protective circuit board, and then these are housed in an outer case and sealed internally. .

  For the purpose of increasing the energy density and weight, for example, a slit (opening) that partially exposes the side surface of the unit cell in the longitudinal direction is provided in the outer case of the battery pack. In order to ensure the strength of the slit, reinforcing bars (ribs) are provided at positions between the adjacent cells in the series direction. In addition, a regulation plate having a certain thickness is interposed between the unit cells adjacent in the series direction so that the unit cell does not break across the crosspiece, so that the unit cell is prevented from coming into contact with the crosspiece. Sometimes

When the unit cells are arranged in parallel inside the battery pack, if one unit cell generates abnormal heat, the heat is transmitted to the surrounding unit cells via the side of the unit battery, and the unit cells are connected in a chain. Abnormal heat generation (hereinafter referred to as “heat chain”) may occur, resulting in a dangerous state. This is a problem that requires an appropriate solution when taking safety measures for battery packs.
Therefore, in the technique described in Patent Document 1, a spacer having a curved side surface with irregularities is disposed between the cylindrical unit cells arranged side by side. An air layer is formed between the spacer on the uneven surface and the side surface of the unit cell to achieve a heat insulating effect during abnormal heat generation.

  In addition, the above-described regulation plate can be expected to act as a heat-resistant wall that prevents the thermal chain of the cells arranged in series.

JP 2008-140629 A JP 2003-7282 A JP 2008-130524 A

However, the conventional battery pack has the following problems.
As disclosed in Patent Document 1, several techniques for preventing the thermal chain of the unit cell of the battery pack have been proposed, but it is difficult to reliably prevent this problem. Further, if the unit cells are separated from each other in order to reliably prevent the thermal chain, the unit cells cannot be appropriately held by the spacer. In addition, the impact resistance of the battery pack is reduced due to the increase in the gap.

  As another problem, it is necessary for the battery pack to improve both the energy density and the production cost. When the restriction plate is provided between the unit cells adjacent in the series direction as described above, the production cost may be increased correspondingly to the number of parts. However, if the restriction plate is simply omitted, the above-described breakage of the crosspiece cannot be prevented, and the heat chain between the adjacent cells in the series direction cannot be prevented.

The present invention has been made in view of the above problems, and as a first object, while maintaining a high energy density, while preventing the thermal chain of the unit cells in the battery pack, take appropriate safety measures, Provided is a highly reliable battery pack that normally exhibits good impact resistance.
Furthermore, as a second object, there is provided a battery pack capable of appropriately securing a gap between the unit cells to prevent thermal runaway of the unit cells and damage to the outer case, and to expect a reduction in production cost.

  In order to solve the above-mentioned problems, the present invention provides a battery pack in which a power generation element is housed in an outer case, and the power generation element includes two or more cylindrical unit cells arranged in parallel with a spacer interposed therebetween. The spacer is composed of a core body made of a resin material that is thermally deformed, and a sheet body made of a material having higher heat resistance than the core body, and each unit cell in the unit cell group includes: The core body is disposed so as to abut on the sheet body.

Here, the core may be composed of HDPE or PC.
Moreover, the said sheet | seat body can also be comprised with a mica.
Furthermore, the said core body has a curved surface part matched with the side surface shape of each said unit cell, It is set as the structure arrange | positioned so that the said curved surface part may contact | abut the side surface of each said unit cell via the said sheet | seat body. You can also

  The power generation element has a plurality of unit cell groups connected in series via a lead member having a convex portion on the surface, and the exterior case is connected in series with a slit that exposes the side surface of each unit cell to the outside. And a bar provided so as to cross the slit at a position between the unit cell groups, and the convex portion of the lead member abuts the unit cell directly or indirectly through a conductive member. Thus, the distance between the group of unit cells connected in series can be defined.

Here, it is preferable that the protruding amount of the convex portion in the lead member is set to be at least equal to or greater than the width of the outer case crosspiece.
The lead member has a pair of connection portions, the convex portion is formed on one surface of at least one of the connection portions, and the pair of connection portions are arranged to face each other in the power generation element. The projecting portion may be in contact with the other connecting portion, and the other surface of each connecting portion may be electrically connected to the unit cell group.

Further, the pair of connection portions may be connected by a connection portion, and the pair of connection portions may be arranged to face each other by being folded back at the connection portion.
In addition, a plurality of the convex portions are formed on each surface of the pair of connection portions, and the convex portions of the connection portions are folded by the connection portions so that the distance is increased. It is also possible to adopt a specified configuration.

Further, when the connection portions are viewed in plan, the convex portions are formed in a long shape, and the long convex portions that are in contact with each other at the pair of connection portions intersect each other in the longitudinal direction. It can also be configured.
The power generation element includes a first unit cell group and a second unit cell group, and one of the pair of connection portions is connected to each unit cell in the first unit cell group. Connected to a terminal of a battery, the other connecting portion is connected to a terminal in each of the unit cells of the second unit cell group, and the distance between the first unit cell group and the second unit cell group is It can also be set as the structure controlled by the convex part.

  The unit cell may be a lithium ion battery.

  In each of the battery packs of each aspect of the present invention having the above-described configuration, the spacer core is in close contact with the cylindrical unit cell via the sheet member. For this reason, in the normal time, each unit cell is reliably held inside the battery pack. Therefore, when the battery pack is dropped or shocked, the disconnection or short circuit of the wiring around the unit cell and the lead member can be prevented, and safety and reliability can be improved. In addition, since the sheet body is in close contact with the side surface of the unit cell, the temperature distribution of the driving heat of the unit cell can be made uniform, and the concentration of heating can be suppressed. Thereby, the life of the battery pack is extended, and stable power supply to the power supply target device is possible. Further, since the core body and the sheet body are in close contact with the unit cell, there is no extra space and there is little possibility of causing a decrease in the energy density of the battery pack.

  On the other hand, if any unit cell in the battery pack generates abnormal heat, the heat of the unit cell is gently transmitted to the core body through the sheet body, and the core body undergoes thermal deformation, thereby causing the core An air layer is formed between the body surface and the sheet body. This air layer is held between the core surface and the sheet body without convection. Therefore, a good heat insulating effect is exhibited and heat conduction to other adjacent unit cells via the core is reduced, so that the thermal chain of each unit cell is reliably suppressed as compared with the conventional case.

Further, due to the high heat insulation effect by such an air layer and the sheet body, even if the core body melts due to heat conduction from the unit cell, it does not melt excessively, and the core body remains between adjacent unit cells. . Therefore, it is possible to effectively prevent the thermal chain of the unit cells that can be generated by convection of a high-temperature air layer between adjacent unit cells as in the prior art.
As described above, according to the present invention, safety measures and reliability of a battery pack can be improved, and high energy density can be favorably maintained.

The “resin material that is deformed by heating” referred to in the present invention refers to a material in which the resin material undergoes at least one of heat shrinkage, thermal deformation, and melting.
Furthermore, in the battery pack according to claim 5, the distance between the unit cells can be regulated by arranging the lead member having a convex portion between the unit cells adjacent in the series direction. For this reason, in the battery pack, there is no need to use a separate regulating plate as in the prior art, and the production cost can be reduced and the production efficiency can be improved by reducing the number of parts. In addition, since the lead member having the convex portion is disposed between the unit cells, the distance between the unit cells is appropriately adjusted according to the protruding amount of the convex portion. Interference with the battery can be prevented, and breakage of the reinforcing rib can be prevented.

1 is a set diagram illustrating a configuration of a battery pack according to Embodiment 1. FIG. FIG. 3 is a diagram illustrating a configuration of a power generation element (core component) according to the first embodiment. FIG. 6 is a diagram illustrating a configuration and effects of a lead member in the core component according to the first embodiment. It is a figure which shows the unit cell group of Embodiment 1, and the structure of spacer periphery. FIG. 6 is a diagram for explaining the configuration and effects of the spacer according to the first embodiment. It is a figure which shows the structure and effect of the lead member of Embodiment 2. FIG. FIG. 10 is a diagram illustrating a configuration and effects of a lead member according to a modification of the second embodiment. FIG. 10 is a diagram illustrating a configuration and effects of a lead member according to a modification of the second embodiment. FIG. 10 is a diagram illustrating a configuration and effects of a lead member according to a modification of the second embodiment. FIG. 6 is a diagram illustrating a configuration of a lead member according to a third embodiment. It is a figure explaining the mode at the time of the assembly of the electric power generation element (core component) of Embodiment 3. FIG. FIG. 10 is a diagram showing the arrangement of each lead member in the power generation element of the third embodiment. It is a figure which shows the effect of the lead member of Embodiment 3. FIG. 10 is a diagram illustrating a configuration of a lead member according to a modification of the third embodiment.

Each embodiment of the present invention will be described below. Needless to say, the present invention is not limited to the following configurations, and can be modified as appropriate without departing from the technical scope of the present invention.
<Embodiment 1>
(Configuration of battery pack 1)
FIG. 1 is an assembled diagram illustrating a configuration of a battery pack 1 according to the first embodiment.

The battery pack 1 includes a power generation element (core component 4) and a protection circuit board (PCBA5) housed inside an outer case (rear case 2 and front case 3).
The exterior case is configured by combining a long rear case 2 having a longitudinal direction in the Y direction and a strip-shaped front case 3. Both the rear case 2 and the front case 3 are formed by injection molding engineering plastics (resins such as ABS and PC) that are excellent in heat resistance, insulation, and mechanical strength.

As an example, the battery pack 1 uses a notebook computer as a power supply target device, and the shape of the outer case is a part of the external shape of the computer.
The rear case 2 is configured in a rectangular parallelepiped shape having a depth in the Z direction in which the core component 4 can be accommodated. A charge / discharge terminal 20 is disposed on one side surface of the outer surface, and a warning label, a rating label, or the like is attached to a main surface below the paper surface. When charging the battery pack 1, the terminal 20 is connected to the power supply target device and receives external power supply through the power supply target device. On the other hand, during normal use, the terminal 20 supplies power to the power supply target device.

Note that a latch (engaging portion) (not shown) that locks the mounted state after the battery pack 1 is mounted on the power supply target device is disposed below the rear case 2. Further, a rib 21 (see the cross-sectional view of FIG. 3B) is provided on the bottom surface of the rear case 2, and each unit cell 40a of the core component 4 housed in the rear case 2 is placed at a predetermined position. Positioned.
The front case 3 is a lid attached to the opening of the rear case 2 and has a length (Y-direction length) substantially equal to that of the rear case 2. The main surface of the front case 3 has a skeleton structure in which two slits 30 for exposing each part of each unit cell 40a,... ing. The slit 30 improves the space efficiency of the battery pack 1 and realizes high energy density. In the slit 30, ribs (reinforcing ribs 31) that reinforce the front case 3 and give rigidity to the adjacent gaps of the unit cell groups 4 </ b> A, 4 </ b> B, and 4 </ b> C arranged in series in the core component 4 cross. Provided.

FIG. 2 is a diagram showing the configuration of the core component 4. FIG. 4 shows the configuration of the unit cell group and the spacer. 4A, 4B, and 4C are respectively an end view of the core component, an XZ cross-sectional assembly diagram of the core component, and an assembly diagram of the unit cell group 4A.
The core component 4 includes three unit cell groups 4A, 4B, and 4C including two cylindrical unit cells 40a, 40b, 40c, 40d, 40e, and 40f connected in parallel in the X direction in series in the Y direction. It has a so-called 3-by-2 parallel structure. Each unit cell 40a, the positive and negative terminals of ... are electrically connected with the lead members P ₁ to P _4. Of course, the number of unit cells used for the core component 4 may be other than six. Here, each unit cell 40a,... Is connected to PCBA ₅ via lead members P _{1 to} P ₄ in order to perform voltage / current management, temperature management, etc. of the unit cell.

In each of the unit cell groups 4A, 4B, and 4C, a spacer 6 is disposed between the unit cells (in this case, 40a and 40b, 40c and 40d, 40e and 40f).
The unit cells 40a,... Are cylindrical secondary batteries and use lithium ion batteries, but the type is naturally not limited thereto. In addition, various secondary batteries such as a nickel metal hydride battery, a nickel cadmium battery, and a lithium ion polymer battery can be given.

The lead members P _{1 to} P ₄ are all made of a conductive material such as a nickel plate (NiP). Lead members P ₁ is a strip-shaped body as shown in FIG. 2, the unit cells 40a, is the negative terminal and spot welding 40b, is bent at a right angle to fit the sides of the unit cell. Lead member P ₄ has a P ₁ and symmetrically shaped, unit cell 40e in the same manner as P _1, and is connected to the positive terminal of the 40f.

Here, FIG. 3 (a) is a developed view of the lead member _{P 2,} FIG. 3 (b) YZ cross-sectional view showing a state of the unit cell 40a, the lead member _{P 2} disposed in the gap 40c is (internal structure of the battery Is omitted).
Specifically, as shown in FIG. 3A, the lead member P < _b > ₂ has a configuration in which a pair of long connecting portions (connecting portions 70 </ b> A and 70 </ b> B) are connected to each other by a connecting portion 73. . A slit for preventing generation of eddy current during resistance welding is provided on the surfaces of the connecting portions 70A and 70B. Lead member _{P 2} are unit cells 40e of the cell group 4C at connection 70A, is connected to 40f, the unit cell 40c of the unit cell group 4B at connection 70B, is connected to 40d. Thereby, the adjacent unit cell groups 4B, 4C each other are connected in series lead member P _2. Lead member _{P 3} has a _{P 2} and symmetrically shaped, the unit cells 40a, the positive electrode terminal and the unit cell 40c of 40b, is connected to the negative terminal of the 40d, the unit cell groups 4A, 4B are connected in series.

Each of these lead members P _{1 to} P ₄ has an extending portion 72 as shown in FIG. 3A, and is electrically connected to PCBA 5 at a connecting portion 70C at the tip of each extending portion 72.
As shown in the cross-sectional view of FIG. 3B, between the unit cell groups included in the core component 4 (between 4A and 4B, between 4B and 4C), an insulating member that regulates the gap L1 to an appropriate value ( A regulating plate 7 made of a resin member or the like is disposed. The restricting plate 7 is configured as a plate that matches the cross-sectional shape of the unit cells 40a,. The arrangement of the regulating plate 7 prevents the unit cells 40a,... From interfering with the reinforcing rib 31 of the front case 3 and damaging the rib 31. Moreover, the effect | action which prevents the thermal chain of unit cell 40a ... is exhibited by providing between unit cell groups (between 4A and 4B, between 4B and 4C) adjacent in a series direction.

  A PCBA (printed circuit board assembly) 5 is an assembled protection circuit board in which predetermined electrical elements are mounted on a board made of a glass epoxy material. In the battery pack 1, in order to appropriately charge and discharge each unit cell 40 a,..., The temperature of each unit cell 40 a,. For this reason, the PCBA 5 monitors the thermistor element, the PTC element that interrupts energization during the thermal runaway of the unit cell 40a,..., And monitors the voltage value / remaining capacity of each unit cell 40a,. A microcomputer having a detection function is mounted on the substrate.

It is also possible to connect an LED element to the circuit of PCBA 5, open a light emitting window of the LED element on the outer surface of the battery pack 1, and provide an LED indicator indicating the remaining battery capacity of the LED element. PCBA5 is used for management when lithium ion batteries are used for the unit cells 40a,..., But PCBA5 is not used when other secondary batteries are used. It may be good.
(Configuration of spacer 6)
As shown in FIGS. 2 and 4A, in each of the unit cell groups 4A to 4C, a spacer 6 is provided between adjacent unit cells 40a,. As shown in FIGS. 4B and 4C, the spacer 6 includes a core body 60 and a pair of sheet bodies 61a and 61b as one set.

  The core body 60 has a relatively good heat resistance and generates a slight deformation (including melting and volume shrinkage) by heating at a certain temperature or higher, such as HDPE (high density polyethylene), PC (polycarbonate), etc. It consists of The core body 60 is interposed between the unit cells 40a arranged in parallel in the unit cell groups 4A, 4B, 4C to avoid direct contact, and at the normal time, the unit cells 40a,. Impact resistance is imparted to the battery pack 1 by appropriately holding.

  As shown in FIG. 2 and FIG. 4C, the core 60 is adjusted to a size that matches the axial length (Y-direction length) of the unit cells 40a,. Each main surface of the core body 60 is a curved surface portion 600a, 600b having a curvature matched to the side surface shape of the unit cell. The size of the core body 60 can be changed as appropriate, but it is preferable to match the size of the unit cells 40a,. Here, as shown in FIGS. 4A and 4B, the width of the core body 60 in the Z direction can be adjusted to the diameter of the unit cells 40a,. I have to. The minimum thickness along the x direction of the core body 60 can be set to about 0.6 mm, for example. Thereby, while maintaining the high energy density of the battery pack 1 favorably, the unit cells 40a and 40b arranged in parallel can be appropriately separated.

  The sheet bodies 61a and 61b are strip-shaped bodies each made of a heat-resistant material (here, mica) having a thickness of 0.2 mm. The sheet bodies 61a and 61b are heat-resistant parts in the spacer 6, and are sandwiched between the side surfaces 400a and 400b of the unit cell and the curved surface parts 600a and 600b of the core body 60 inside the core part 4, and are normally not driven during driving. The heat generation temperature distribution of the batteries 40a, ... is made uniform.

  In the above example, the core body 60 is made of HDPE or PC, and the sheet bodies 61a and 61b are made of mica. However, the materials of the core body 60 and the sheet bodies 61a and 61b are not limited to these, and other materials May be used. The sheet bodies 61a and 61b may be made of a material having at least higher heat resistance than the core body 60. However, since the sheet bodies 61a and 61b are required to bend along the side surface shape (and the curved surface portions 601a and 601b) of the unit cells 40a,..., It is necessary to use a material having appropriate flexibility. . The sheet bodies 61 a and 61 b do not have to be separate from each other, and can be integrally formed as a continuous belt-like body and disposed so as to surround the core body 60. In this way, since the temperature distribution of the sheet bodies 61a and 61b is made uniform, local overheating of the sheet bodies 61a and 61b in contact with the unit cells 40a,. The improvement of the effect which prevents the heat chain by the heat radiation of the time and convection heat can be expected further.

Here, if both the core body 60 and the sheet bodies 61a and 61b are made of the same heat-resistant material or a similar heat-resistant material, the distribution of driving heat of the unit cells 40a,. By making it uniform, the thermal stability can be exhibited and the life of the battery pack 1 can be extended. However, if the sheet bodies 61a and 61b are made of a resin material, there is a risk of melting with the heat of the abnormally heated unit cells 40a,..., So the core body 60 and the sheet bodies 61a and 61b are made common. In some cases, it is desirable to use an inorganic material.
(About the effect of the battery pack 1)
In the battery pack 1 having the above-described configuration, as shown in FIG. 5A, the core body 60 of the spacer 6 appropriately connects each unit cell 40a, 40b,... Appropriately through a pair of sheet bodies 61a, 61b. Hold. In particular, since both main surfaces of the core body 60 are configured as curved surface portions 601a, 601b adjusted to a concave shape in accordance with the shape of the side surfaces 400a, 400b of the unit cells, each of the unit cells 40a, 40b. The sheet body 61a, 61b is held without a gap while being fitted into the curved surface portions 601a, 601b. As a result, even when an impact such as a drop or a collision is applied to the battery pack 1 during use, good rigidity can be exhibited, the occurrence of an internal short circuit or disconnection can be prevented, and the reliability of the battery pack 1 can be improved.

On the other hand, if the sheet bodies 61a and 61b are made of a material that is more excellent in thermal conductivity than the core body 60, the temperature distribution of each unit cell 40a, 40b,... Can be made uniform to some extent by the sheet bodies 61a and 61b. Expected and stable driving can be realized.
Here, when any of the unit cells 40a in the battery pack 1 abnormally generates heat, as shown in FIG. 5 (b), the sheet bodies 61a and 61b are attached to the unit cells 40a. Through which the core 60 is melted or thermally deformed by heat conduction from the unit cells 40a. Thereby, air layers 602a and 602b are formed on the surface of the core body 60 facing the sheet bodies 61a and 61b, as shown in FIG. Since the air layers 602a and 602b remain at the same position between the sheet bodies 61a and 61b and the core body 60, low thermal conductivity (high heat insulation effect) is exerted, and excessive heat of the unit cells 40a,. (Including various kinds of heat such as radiant heat and convection heat) is prevented from conducting heat to the adjacent unit cells 40a,. Thereby, the thermal chain of each unit cell 40a, ... is effectively prevented.

  At this time, heat conduction from the heated unit cells 40a,... To the core body 60 is performed via the sheet bodies 61a, 61b and the air layers 602a, 602b having a high heat insulating effect. .. High heat is not easily transmitted to the core body 60 side, and the resin of the core body 60 does not melt excessively. For this reason, it can prevent that the core body 60 elutes completely between the adjacent unit cells 40a ... even in a high temperature state. Therefore, the adjacent unit cells 40a, ... are not in direct contact with each other for a long time even in a heated state, and the air layers 602a, 602b having a heat insulating effect are compared between the core body 60 and the sheet bodies 61a, 61b. Is kept stable. Further, the core body 60 is held between the adjacent unit cells 40a,... Can block the heat convection of the air inside the battery pack 1, and this also reduces the increase in heating temperature.

Furthermore, if the sheet bodies 61a and 61b are made of a material such as mica having excellent insulating properties, each unit cell 40a can be appropriately insulated when an abnormal temperature occurs, and problems such as occurrence of a short circuit due to a thermal chain are caused. Can be minimized.
Such an effect is particularly good in a battery pack that uses a plurality of high-capacity cells, such as a battery pack used as a power source for notebook PCs, etc., and has a small internal volume and a small heat escape. Is done.

<Performance confirmation test>
Next, a test for confirming the effect of the spacer of the present invention was performed according to the following procedure.
A unit cell group in which a spacer made of a predetermined material (see Table 1) and a structure having a uniform thickness of 1 mm was sandwiched between two unit cells was produced. In addition, a unit cell group in which a distance of 1 mm was provided between two unit cells without using a spacer was also produced.

  Two unit cell groups having the same configuration were arranged in series using a lead member, a dummy unit cell group to which no power source was connected was arranged, and a core part having a three-by-two structure as a whole was produced. By this procedure, a core component was produced for each unit cell group of spacers (and spacers not used) made of a predetermined material (see Table 1) (Comparative Examples 1 to 9, Examples). Here, a plurality of the same core parts of each of the comparative examples and the examples were prepared.

Next, the produced core components were placed on a table, and charging was started at a room temperature (20 ° C.) with a 4.2 V charging voltage. Then, a specific unit cell of the core part was intentionally run away from heat, and changes occurring around the spacer were observed.
The experimental results are shown below.
The item “Result” in the table indicates that in the plurality of core parts of each of Comparative Examples 1 to 9 and Examples, adjacent unit cells juxtaposed with the unit cells that intentionally caused thermal runaway reach the thermal chain. Evaluated by probability. “X” indicates that the adjacent unit cells arranged in parallel reach the thermal chain in all of the plurality of core components. “◯” indicates that a plurality of core components include those that do not cause a thermal chain among adjacent unit cells arranged in parallel. “◎” indicates that the adjacent unit cells arranged in parallel in all of the plurality of core components did not form a thermal chain.

（結果と考察）
いずれのサンプルのコア部品においても、熱暴走させた素電池に隣接する素電池が加熱され、内部の電解液を含むガスが安全弁から噴出した。さらに、加熱を続けると、素電池間に介設されているスペーサーが高温の素電池によって加熱され、熱連鎖により損失する場合も確認した。

(Results and discussion)
In any of the core components of the sample, the unit cell adjacent to the unit cell subjected to thermal runaway was heated, and the gas containing the internal electrolyte solution was ejected from the safety valve. Furthermore, when heating was continued, it was confirmed that the spacer interposed between the unit cells was heated by the high-temperature unit cell and lost due to the heat chain.

Next, the experimental results of each sample are considered individually.
As shown in Table 1, the heat chain of each unit cell was confirmed in the sample in which the side surfaces of each unit cell were in close contact, or in the sample (Comparative Examples 1 and 2) in which a space of 1 mm width was placed between each unit cell. did.
In addition, generation of heat loss was confirmed in samples (Comparative Examples 3 to 5) in which polycarbonate (PC), acrylic fiber, and ceramic fiber were used alone as spacer materials. On the other hand, in the samples (Comparative Examples 6 and 7) each using UL fiber and mica alone, a certain effect of preventing heat loss was confirmed, but the effect was still insufficient.

For each of these samples (Comparative Examples 1 to 7), in the examples, the use of a spacer formed by sandwiching a core body (HDPE) between a pair of sheet bodies (mica) provides a good heat insulating effect due to the sheet body. It was confirmed that the heat loss of the core made of HDPE sandwiched between the sheet bodies was prevented.
In Comparative Example 2, it seems that a certain heat insulation effect was also achieved by an air layer having a width of 1 mm existing between adjacent unit cells, but as a result, the thermal chain of the unit cells was confirmed. This is considered to be because the air layer heated to a high temperature convects between adjacent unit cells and thermal diffusion occurs.

  Moreover, although the comparative example 9 is a structure which provided the air layer except the core body from the structure of the spacer of an Example, and this was pinched | interposed with a pair of mica, it may produce a heat chain compared with an Example. It was confirmed. This is because, in Comparative Example 9, the air layer existing between the pair of mica is heated by the heat generated by the unit cell and is convected, and as in Comparative Example 2, thermal diffusion occurs. Conceivable. In this regard, Comparative Example 9 shows that there remains a problem in terms of reliability.

On the other hand, in Comparative Example 8, since the spacer was composed only of the core (HDPE), the spacer was almost melted (eluted) by heat. As a result, the adjacent unit cells contacted each other, resulting in the occurrence of a thermal chain.
On the other hand, in the examples, despite the use of the same core as in Comparative Example 8, the thermal chain of the unit cells was not confirmed. This is because the core body is thermally deformed at the heating temperature, an air layer is formed between the sheet body and the core body, and excessive melting of the core body is prevented by the heat insulating effect of the sheet body, and the air layer As a result, it is considered that the heat insulation effect by the air layer is maintained well and the thermal chain of the unit cell is prevented.

From the above experiments, the superiority of the present invention over the prior art could be confirmed.
<Embodiment 2>
Hereinafter, the battery pack according to the second embodiment of the present invention will be described focusing on differences from the first embodiment.
The main features of the battery pack according to the second embodiment are that the lead member P ₂₀ disposed between the unit cell group 4A and the unit cell group 4B of the core component 4 and the unit cell group 4B and the unit cell group 4C. The configuration of the arranged lead member P ₃₀ and the restriction plate 7 are not used. The entire configurations of the unit cell groups 4A to 4C and the battery pack are the same as those in the first embodiment.

Developed view of these, FIG. 6 (a) lead member _{P 20,} omitted cross-sectional view (cross-sectional structure of the battery which shows the state of FIG. 6 (b) unit cell 40a, the lead member _{P 20} disposed in the gap 40c Is).
Although the overall configuration of the lead member _{P 20} is substantially the same as the lead member _{P 2} (see FIG. 3 (a)), in the center of one connection portion (here 70D is), member thickness direction of the lead member _{P 20} (Y A projecting portion 71 projecting in the direction along the axis) is provided.

  In the configuration example shown in FIG. 6, the convex portion 71 is formed by drawing into a shape having a rectangular top. The connecting portion 70E is folded back to face the connecting portion 70D at the connecting portion 73 (FIG. 6B). Due to the presence of the convex portion 71, the positions of the unit cells 40a and 40c are regulated at a distance (gap L1) corresponding to the height of the convex portion 71 and the member thickness of the connecting portion 70E. For this reason, it is not necessary to use the restriction plate 7.

  As a result, in the battery pack according to the second embodiment, the gap between the unit cell groups adjacent in the series (Y) direction can be appropriately regulated. Therefore, the reinforcing rib 31 formed in the front case 3 and the unit cells 40a,. Thus, the core component 4 can be appropriately housed inside the outer case without damaging the reinforcing rib 31. Therefore, even if the restriction plate 7 is not interposed between the adjacent unit cells 40a, 40c (40b, 40d), the same effect as that obtained by using the restriction plate 7 is achieved, and the number of parts of the battery pack is reduced. It can be expected to improve production efficiency and reduce production costs. Moreover, since the unit cells 40a and 40c (40b and 40d) adjacent in the series (Y) direction are separated, thermal runaway of the unit cells along the same direction can be effectively prevented.

  Further, the amount of protrusion of the protrusion 71 in the direction along the Y axis is such that at least the gap L1 is along the Y axis of the crosspiece 31 in order to avoid interference between the unit cells 40a,... And the crosspiece 31 of the front case 3. Set to be greater than or equal to the width of the direction. However, it should be noted that if the gap L1 is too large, the energy density and strength of the battery pack will be insufficient. The setting of the protruding amount of the convex portion 71 in the direction along the Y axis can be adjusted using a predetermined mold in consideration of the workability of the lead plate.

Although not shown, the lead member P ₃₀ also has a configuration similar to that of the lead member P _20, between the unit cell group 4B and the unit cell group 4C, exerts lead member P ₂₀ and effect.
<Modification 1 of Embodiment 2>
In the battery pack of the second embodiment, the number of convex portions provided on the lead member is not limited to one, and may be provided over two or more.

Here, FIG. 7 is a diagram showing a configuration of the lead member P ₂₁ according to the first modification of the second embodiment. In the first modification, as shown in FIG. 7A, the protrusions 71 and 71 project on the surfaces of the connection portions 70F and 70G so that the top portions come into contact with each other when the connection portions 73 are folded back. It is installed.
Accordingly, as shown in FIG. 7B, the gap L1 is determined by the total height of the convex portions 71 and 71 projecting from each other at the top. Even with a battery pack having such a configuration, the same effect as in the second embodiment can be expected.

<Modification 2 of Embodiment 2>
In the battery pack of the second embodiment, the top shape of the convex portion 71 is not limited to a rectangular shape as shown in FIG. 6, and is formed in a circular shape, a plurality of spots (dots), a frame shape, a wave shape, or the like. Also good. Furthermore, it is possible to project convex portions outward from both main surfaces of the lead member.
Here, FIG. 8 is a diagram showing the structure of a lead member P ₂₂ according to the second modification of the second embodiment. In the second modification, as shown in FIG. 7A, three frustoconical convex portions 74 are formed at regular intervals on the surface of the connecting portion 70H, and the surface of the connecting portion 70I is formed on each apex 74. constitute the lead member P ₂₂ to abut.

According to such a configuration, as shown in FIG. 8 (b), the gap L1 is set by contacting the top of each convex portion 74 with the surface of the connecting portion 70I, as shown in FIG. The same effect as 2 is produced.
<Modification 3 of Embodiment 2>
In the battery pack according to the second embodiment, it is possible to dispose only one connection portion per lead member.

Here, FIG. 9 is a diagram showing a configuration of the lead member P ₂₃ according to the third modification of the second embodiment. In the third modification, as shown in FIG. 9 (a), the lead member P ₂₃ has only one connection portion 70 J, to form a relatively large convex portion 71 on the surface thereof. Lead member P ₂₃ is convex portion 71 is resistance welded in a state of contact directly on the end portion of the adjacent unit cells 40a.
As a result, even in the battery pack of Modification 3, the gap L1 is restricted according to the height of the convex portion 71, and the same effect as in the second embodiment is achieved. Further, since the configuration of the modification 3, the lead member P ₂₃ is relatively simple, further Hakare reduction member in addition to the omission of the regulation plate 7, and, by the adoption of short current paths lead member P _23, Reduction of internal resistance can be expected. Also at the time of manufacturing, resistance current when performing the resistance welding can focus on the lead member P _23, and can form a good connection region between the adjacent unit cells 40a, 40c.

<Embodiment 3>
Next, a battery pack according to Embodiment 3 of the present invention will be described. The overall configuration of the battery pack is substantially the same as that of the first embodiment shown in FIG. 1, but has a main feature in the lead member.
(Configuration of lead member)
FIG. 10 shows the configuration of the lead member P ₃₄ used for the battery pack according to the third embodiment. FIG. 10A is a developed perspective view of the lead member P ₃₄ before bending, and FIG. 10B shows the lead member P ₃₄ after bending.

As shown in FIG. 10 (a), the lead member _{P 34} is a processed plate body punching a metal plate made of such as _P 1 to P ₄ described above as well as NiP or the like. In appearance, it has a pair of connecting portions 80A and 80B connected by connecting portions 805a and 805b, and an extending portion 80C extending from the end of the connecting portion 80A in the X direction.
The connection portions 80A and 80B are plate-like portions including main surfaces 801 to 804 having shapes matched to the end surface shapes of two unit cells arranged in parallel in the unit cell group. Connection portion 80A is electrically connected to unit cell group 4B on main surface 804, and connection unit 80B is electrically connected to unit cell group 4C on main surface 802.

On the other hand, the main surfaces 803 and 801 of the connection portions 80A and 80B are formed by extruding a member at the same height from the back surface (main surfaces 804 and 802) side in the direction along the Y axis, thereby forming a long convex shape. Portions 806a to 806d, 807a to 807f, and 808a to 808f are provided at predetermined intervals.
When the connecting portions 805 and 805 are bent so that the connecting portions 80A and 80B face each other, the elongated convex portions 806a, 806b, 807a to 807c, and 808a to 808c of the connecting portion 80A are elongated to the connecting portion 80B. It abuts on the convex portions 807d to 807f, 808d to 808f, 806c, and 806d. Specifically, of the long convex portions, 806a and 806b are in contact with 806c and 806d, 807a is in contact with 807e, 807b is in contact with 807e, 807c is in contact with 807f, and 808a is in contact with 808e. , 808b abuts on 808d and 808c abuts on 808f.

  As a result, the gaps between the main surfaces 801 and 803 of the pair of connection portions 80A and 80B are defined, and as shown in FIGS. 13 (a) and 13 (b), a constant gap L1 is also formed between adjacent unit cells in the series direction. (Gap along the Y axis) is defined. As in the second embodiment, the value of the gap L1 is equal to or greater than the width along the Y-axis of the crosspiece 31 of the front case 3 so that the long convex portions 806a to 806d, 807a to 807f, and 808a to 808f. Set and adjust the amount of protrusion along the Y axis.

Here, when the connection portions 80A and 80B are viewed in a plan view, the long convex portions 806a to 806d, 807a to 807f, and 808a to 808f are, as shown in FIG. It is formed so that the directions intersect. Thus connecting portion 805a of the lead member _{P 34,} even if there is a slight precision displacement when bending at 805b, as the gap reliably major surface 801 and 803, it can form the constant gap L1.

A plurality of slits 809a to 809l are provided between the adjacent long convex portions 807a to 807f and 808a to 808f for the purpose of preventing the generation of eddy currents.
(Assembling core parts)
Next, a method for manufacturing a core component in the battery pack of Embodiment 3 will be described with reference to FIGS.

First, in the core part 4X being manufactured, the lead member P ₁ is connected to the negative electrode side of the unit cell group 4A, and the connecting portion 70L of the lead member P ₂ is connected to the positive electrode side by spot welding, respectively (FIGS. 11 and 12A). (B)).
Then, the connection portions 70K of the lead member _{P 2} to the positive side of the cell group 4B connected by the spot welding (11, FIG. 12 (a)).

Next, connect the lead member _{P 4} to the positive electrode side of the cell group 4C ((11, FIG. 12 (a)). Further, the connection portion 80B of the lead member _{P 34} on the negative electrode side of the battery cell group 4C, containing connecting the connection portion 80A of the lead member _{P 34} to the positive electrode side of the battery group 4B (11, FIG. 12 (b)).
When all the connection of the lead members is completed, the extending portions of the lead members P ₂ and P ₄ are folded back along the line Q (the dashed line in FIG. 12A), and the side surfaces of the unit cells 40d and 40f are arranged in the same order. (Fig. 11).

Similarly, folded along the extending portion of the lead member _{P 34} to the line S (chain line longitudinal direction a point FIG. 12 (b)), placed along the sides of the unit cell 40d (Fig. 11). Lead member P ₄ at this time, while achieving the insulation through an insulating sheet 8, placed along the side surface of the unit cell 40f. Similarly, the lead member P ₃₄ is also insulated along the insulating sheet 9 and along the side surface of the unit cell 40d.
Next, bending the lead member P ₃₄ along the axis of rotation R (one-dot chain line in FIG. 11), folded back 180 ° to the unit cell group 4C in the unit cell group 4B side.

Furthermore, along the dashed line P shown in FIG. 12 (a), folded back 180 ° to the principal surface portion 70K of the lead member _{P 2} in the main surface portion 70J side. As a result, the core components 4 arranged in three rows and two rows as in FIG. 1 are completed.
FIG. 13 shows the state of the lead member 34 in the core component after completion. FIG. 13A shows the BB ′ cross section of FIG. 10B, and FIG. 13B shows the AA ′ cross section of FIG. 10B.

As shown in these figures, the interposition of the lead member _{P 34,} the unit cell 40c, is between 40e constant gap (L1) is formed. This constant gap (L1) is such that, among the long convex portions, 806a and 806b are in contact with 806c and 806d, 807a is in contact with 807e, 807b is in contact with 807e, 807c is in contact with 807f, and 808a is It is formed by contacting 808e, 808b contacting 808d, and 808c contacting 808f.
(Effect of the lead member _{P 34)}
By using such a lead member P _34, which achieves the same effect as the second embodiment. That is, appropriately regulating the gap of the cell group adjacent to the series (Y) direction by adoption of the lead member P _34, preventing each interference with the reinforcing ribs 31 and the unit cell 40a~40f of the front case 3 . As a result, the core component 4 can be appropriately stored inside the outer case without damaging the reinforcing rib 31 without using the regulation plate 7, and a reduction in production cost can be expected by reducing the number of components. Further, due to the presence of the gap L1, thermal runaway of the adjacent cells in the series (Y) direction can be effectively prevented.
<Modification of Embodiment 3>
In the third embodiment, the configuration of the lead member P ₃₄ provided between the unit cell groups 4B and 4C is exemplified, but the lead member provided between the unit cell groups 4A and 4B (corresponding to P2 shown in FIG. 12A). ), Long convex portions similar to the long convex portions 806a to 806d, 807a to 807f, and 808a to 808f are provided, and the same effect can be obtained.

FIG. 14 shows a configuration of a lead member P ₂ ′ according to a modification of the third embodiment. Convex portions 701a to 701d and 702a to 702f are provided on the opposing main surfaces of the connecting portions 70K ′ and 70L ′ of the lead member P ₂ ′ so as to cross and contact each other in the longitudinal direction.
In assembling the core component 4X, the lead member P ₂ ′ is bent along the alternate long and short dash line P. At this time, among the convex portions, 702a abuts 701a, 702d abuts 701d, 702b and 702c abuts 701b and 701c, and 702f and 702e abut 701f and 701e. Thereby, a constant gap similar to L1 shown in FIG. 13 is formed between the unit cell groups 4A and 4B.

<Other matters>
The outer can shape of the unit cell used in the battery pack of the present invention is not limited to a cylindrical shape, and may be a rectangular tube shape, a polygonal tube shape, an elliptical shape, or the like. Further, the axial length of the unit cell is not limited, and a flat unit cell can be used.
The spacer 6 illustrated in each embodiment is a core body 6 and a sheet body that match the lengths of a pair of unit cells arranged side by side. However, the lengths of the core body 60 and the sheet bodies 61a and 61b are It can also be set to an integer multiple of the battery axial length. In this way, a plurality of unit cells arranged in series can be assembled to one set of spacers. In this case, a method may be considered in which a resistance current is passed through the entire core component 4 to electrically connect the conductive members.

  In the present invention, the lead member provided between the unit cell groups 4A and 4B, 4B and 4C is not limited to an integral structure in which a pair of connection portions are connected by a connection portion. That is, the pair of connection portions may be configured as separate conductive members. Also in this case, a method is considered in which a resistance current is passed through the entire core component to electrically connect the conductive members. However, it is preferable to integrally configure the pair of connection portions so that the connection portions are connected to each other because it is advantageous in improving conductivity and positioning of the connection portions.

  In the lead member according to the third embodiment, the arrangement, number, and shape of the long convex portions 806a,... And the slits 809a, are not limited to the configuration shown in FIG. It can be changed. For example, the groups of convex portions 807a to 807c, 807d to 807f, 808a to 808c, and 808d to 808f can be integrated respectively. In this case, it is necessary to omit the slits 809b, 809c, 809e, 809f, 809h, 809i, 809k, and 809l.

The battery pack according to the present invention can be widely used as a main power source for small electronic devices such as portable DVD players, portable GPS, and transceivers, in addition to notebook computers and PDAs. Alternatively, it can be applied to relatively large devices such as power assist bicycles and electric tools.
The battery pack according to the present invention has a low risk of heat chain at the time of occurrence of a malfunction, and is extremely safe, so that it can be widely used. In addition, the size of the battery pack can be set freely, and its applicability is extremely large.

_{P 1, P 2, P 2} ', P 3, P 4, P 20 ~P 23, P 34 lead member 1 battery pack 2 rear casing 3 front case 4 core component (power generating element)
4X Core parts under assembly 4A, 4B, 4C Unit cell group 5 PCBA (assembled protection circuit board)
6 Spacer 7 Restriction plate 21 Rear case rib 30, 809a to 809l Slit 31 Reinforcement rib (crosspiece)
40a, 40b, 40c, 40d unit cell 60 core body 61a, 61b sheet body 70A-70L, 70K ', 70L', 80A, 80B, connection part 71 convex part 72 extension part 73, 805a, 805b coupling part 400a, 400b, 400d, 400f Unit cell side surface 600a, 600b Core curved surface portion 601a, 601b Sheet body main surface 602a, 602b Air layer 701a-701f, 702a-702f, 806a-808d, 807a-808f, 808a-808f Long convex portion

Claims (12)

A battery pack in which a power generation element is housed in an outer case,
The power generation element includes a unit cell group in which two or more cylindrical unit cells are arranged in parallel with a spacer interposed therebetween,
The spacer is composed of a core body made of a resin material that is thermally deformed and a sheet body made of a material having higher heat resistance than the core body,
Each unit cell in the unit cell group is disposed so as to contact the core body via a sheet body. The battery pack according to claim 1, wherein the core is made of HDPE or PC. The battery pack according to claim 1, wherein the sheet body is made of mica. The core body has a curved surface portion adapted to the side shape of each unit cell,
The battery pack according to any one of claims 1 to 3, wherein the curved surface portion is disposed so as to contact a side surface of each unit cell via the sheet body. A plurality of the unit cell groups are connected in series to the power generation element via a lead member having a convex portion on the surface,
The exterior case has a slit that exposes the side surface of each unit cell to the outside, and a crosspiece provided to cross the slit at a position between the unit cell groups connected in series,
The distance between the unit cell groups connected in series is defined by the convex part of the lead member contacting the unit cell directly or indirectly through a conductive member. The battery pack according to any one of 1 to 4. The battery pack according to claim 5, wherein an amount of protrusion of the convex portion in the lead member is set to be at least equal to or greater than a width of the crosspiece of the exterior case. The lead member has a pair of connection portions,
The convex portion is formed on one surface of at least one of the connection portions,
In the power generation element, the pair of connection portions are arranged to face each other, so that the convex portion comes into contact with the other connection portion,
The battery pack according to any one of claims 5 and 6, wherein the other surface of each connection portion is electrically connected to the unit cell group. The battery pack according to claim 7, wherein the pair of connection portions are connected by a connection portion, and the pair of connection portions are arranged to face each other by being folded back at the connection portion. A plurality of the convex portions are formed on each surface of the pair of connection portions,
The pack according to any one of claims 5 to 8, wherein the convex portion of each connection portion has the distance defined by the connection portions being folded back at the connecting portion and abutting each other. battery. When each connection portion is viewed in plan, the convex portion is formed in a long shape,
10. The battery pack according to claim 9, wherein the long convex portions that abut on each other at the pair of connection portions intersect each other in the longitudinal direction. The power generation element includes a first unit cell group and a second unit cell group,
Of the pair of connection portions, one of the connection portions is connected to a terminal of each unit cell in the first unit cell group,
The other connecting portion is connected to a terminal in each unit cell of the second unit cell group,
The battery pack according to any one of claims 5 to 10, wherein a distance between the first unit cell group and the second unit cell group is regulated by the convex portion. The battery pack according to any one of claims 1 to 11, wherein the unit cell is a lithium ion battery.

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