JP5866939B2 - Electrical device - Google Patents

Description

  The present invention relates to an electric device such as a lithium ion secondary battery.

  In a power generating element in which a negative electrode, a separator, and a positive electrode are laminated in this order, there is a lithium ion secondary battery in which the extending directions of adjacent separators intersect each other (see Patent Document 1).

Special table 2010-514105 gazette

  In the technique of the above-mentioned Patent Document 1, although the external force is dispersed as a whole of the power generation element, protection of the outermost layer portion of the power generation element and the side surface of the power generation element, which is a structurally weak part against the external force, is considered. It is not done. Therefore, when an external force is applied to the outermost layer portion of the power generation element or the side surface of the power generation element, the separator close to the outermost layer portion or the side surface may be broken and short circuit may occur due to direct contact between the positive electrode and the negative electrode.

  Then, an object of this invention is to provide the electric device which can protect the outermost layer part of a power generation element and the side surface of a power generation element.

  The electric device of the present invention is intended for a power generation element in which a negative electrode, a separator, and a positive electrode are stacked in this order. And it is the 1st and 2nd sheet | seat comprised from the resin porous body which has an extending | stretching direction, Comprising: The extending | stretching direction of a 1st sheet | seat and the extending | stretching direction of a 2nd sheet | seat cross | intersect the said electric power generation element Are provided with the first and second sheets that overlap the whole.

  ADVANTAGE OF THE INVENTION According to this invention, the outermost layer part of the electric power generation element and the side surface of an electric power generation element which are structurally weak parts with respect to external force can be protected from external force. For example, when a power generation element is placed with the stacking direction set to the vertical direction, the two outermost surfaces (upper and lower surfaces) of the power generation element in the stacking direction are covered with two sheets with different stretching directions. It has become strong in terms of being. On the other hand, since the side surface of the power generation element is covered with a sheet having the stacking direction as the extending direction, it is strong against external force from the horizontal direction toward the side surface. As a result, it is possible to prevent tension from acting locally on the portion where the ability to receive force is weak, breaking the separator and causing the positive electrode and the negative electrode to be in direct electrical contact and short-circuiting. The reliability (safety) of the electric device can be greatly improved.

It is a top view of each 1st and 2nd sheet | seat of 1st Embodiment of this invention. It is a schematic perspective view of 1st Embodiment which shows the state which coat | covered the electric power generation element with the 1st sheet | seat. It is a schematic perspective view of 1st Embodiment which shows the state which coat | covered the electric power generation element with the 1st, 2nd sheet | seat. It is a disassembled perspective view of an electric power generation element. It is a schematic perspective view of the whole battery. It is a schematic perspective view of 2nd Embodiment which shows the state which coat | covered the electric power generation element with the 1st, 2nd, 3rd sheet | seat. It is a top view of the 3rd sheet of a 2nd embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the dimension ratio of drawing has the location exaggerated on account of description, and the location differs from the actual ratio.

(First embodiment)
The lithium ion secondary battery 1 of this embodiment is demonstrated. FIG. 1 is a plan view of the first and second sheets 21 and 22. 2 is a schematic perspective view showing a state in which the power generation element 2 is covered with the first sheet 21. FIG. 3 is a schematic perspective view showing a state in which the power generation element 2 is covered with the first and second sheets 21 and 22. FIG. 4 is an exploded perspective view of the power generation element 2, and FIG. 5 is a schematic perspective view of the entire battery.

  Here, in the lithium ion secondary battery 1, the substantially square flat power generation element 2 in which the charge / discharge reaction actually proceeds is sealed inside the laminate film 14 that is a battery exterior material as shown in FIG. 5. Has a structure. Specifically, the power generation element 2 is housed and sealed by joining a peripheral part (peripheral part) by thermal fusion using a polymer-metal composite laminate film as a battery exterior material. . Here, the polymer-metal composite laminate film generally has a three-layer structure in which a metal film is sandwiched between polymer films (resin films).

  Such a stacked battery 1 is referred to as a “laminated battery” in order to be distinguished from a can battery. A can-type battery is one in which two electrodes are wound and housed in a hard cylindrical metal outer frame like a commercially available AA battery or AA battery. On the other hand, the laminate type battery is a battery in which the power generation element is sealed by joining the peripheral portion (peripheral portion) of the substantially square flat power generation element 2 by thermal fusion. Hereinafter, the lithium ion secondary battery 1 is referred to as a “laminated battery”. Alternatively, it is simply called “battery”.

  In this embodiment, after covering the whole electric power generation element 2 with the 1st, 2nd sheet | seats 21 and 22 mentioned later, a laminate film is used as a battery exterior material, and the peripheral part (peripheral part) is heat-seal | fused. In this way, the power generation element 2 is housed and sealed. For this reason, the electric power generation element 2 is demonstrated previously with reference to FIG.

  As shown in FIG. 4, the power generating element 2 has a configuration in which the negative electrode 4, the separator 12, and the positive electrode 8 are stacked in this order. Here, the negative electrode 4 is obtained by disposing negative electrode active material layers 6 and 6 on both sides of a rectangular thin plate-like negative electrode current collector 5. Similarly, the positive electrode 8 is obtained by disposing positive electrode active material layers 10 and 10 on both sides of a rectangular thin plate-shaped positive electrode current collector 9. The separator 12 is mainly formed from a porous thermoplastic resin. Since the separator 12 holds the electrolytic solution, an electrolyte layer is formed integrally with the separator 12.

  Thereby, the adjacent negative electrode 4, the separator 12, and the positive electrode 8 comprise one single cell layer 13 (single cell). Therefore, it can be said that the laminate type battery 1 of the present embodiment has a configuration in which the single battery layers 13 are stacked to be electrically connected in parallel. Further, a seal portion (insulating layer) for insulating between the adjacent negative electrode current collector 5 and positive electrode current collector 9 may be provided on the outer periphery of the unit cell layer 13. The outermost negative electrode current collectors 5 located on both outermost layers of the power generation element 2 are all only on one side (in FIG. 4, the uppermost negative electrode current collector 5 has only the lower surface, and the lowermost negative electrode current collector 5 has Is disposed on the upper surface only). Note that the arrangement of the negative electrode and the positive electrode is reversed from that in FIG. 4 so that the outermost positive electrode current collector is positioned in both outermost layers of the power generation element 2, and the positive electrode is provided only on one side of the outermost positive electrode current collector. An active material layer may be disposed.

  The negative current collector 5 and the positive current collector 9 are attached with high voltage tabs 15 and 16 that are electrically connected to the respective electrodes (negative electrode and positive electrode). Since the power generation element 2 is formed in a square flat shape having four sides as a whole, the two high-power tabs 15 and 16 are collectively led out from only one side of the four sides (see FIG. 5).

  Now, since the battery exterior material is a laminate film as compared with the can type battery, the laminate type battery 1 has the outermost layer portion in the stacking direction of the power generating element 2 (vertical direction in FIG. 4) and the stacking direction of the power generating element 2. There is a problem that the side surfaces in the orthogonal direction (left-right direction in FIG. 4) are structurally particularly weak against external forces such as collision and vibration. Here, the laminate type battery will be mainly described, but the present invention is not limited to the laminate type battery. For example, the same applies to an electric device in which a power generation element is covered with a resin exterior body. For such an electric device, the outermost layer portion in the stacking direction of the power generation element and the side surface in the direction orthogonal to the stacking direction of the power generation element are also included. There is a problem that it is structurally weak against external forces such as collision and vibration.

  For this reason, in a power generation element in which a negative electrode, a separator, and a positive electrode are laminated in one direction, there is a conventional device in which the extending directions of adjacent separators intersect each other. This is because the separator is often uniaxially stretched at the time of manufacture, so even if it receives a force in the stretching direction, the separator will not break, but when it receives a force in a direction perpendicular to the stretching direction, It may be torn. When the separator is broken, the positive electrode and the negative electrode are directly electrically connected to cause a short circuit. Therefore, by arranging adjacent separators so that the extending directions cross each other, the power generation element as a whole can receive a force in the extending direction of the separator, or can receive a force in a direction orthogonal to the extending direction. The separator in the power generation element is prevented from being broken.

  However, although the conventional device has a structure in which the external force is dispersed as a whole of the power generation element, protection of the outermost layer portion and the side surface of the power generation element, which is a structurally weak portion against the external force, is not considered. Therefore, when an external force is applied to the outermost layer portion of the power generation element or the side surface of the power generation element, the separator close to the outermost layer portion or the side surface may be broken and may be short-circuited by direct contact between the positive electrode and the negative electrode.

  Therefore, in the present embodiment, first and second sheets 21 and 22 made of a resin porous body having a stretching direction are prepared, and the entire power generating element 2 is covered with the first and second sheets 21 and 22. At the same time, the stretching direction of the first sheet 21 and the stretching direction of the second sheet 22 are orthogonal (intersected). Hereinafter, this point will be described in detail with reference to FIGS.

  The first and second sheets 21 and 22 composed of a porous resin body such as polypropylene and polyethylene are often manufactured by a uniaxial stretching method. A sheet produced by the uniaxial stretching method has a difference in tensile strength between the stretching direction and the direction orthogonal to the stretching direction. That is, the tensile strength in the stretching direction (vertical direction in FIG. 1) is larger than the tensile strength in the direction orthogonal to the stretching direction (horizontal direction in FIG. 1). In other words, the elongation in the stretching direction (vertical direction in FIG. 1) is larger than the elongation in the direction orthogonal to the stretching direction (left and right direction in FIG. 1). In FIG. 1, the extending direction is indicated by a striped pattern, but the striped pattern does not actually exist. The first and second sheets 21 and 22 may be made of a single material such as polypropylene or polyethylene, or may be a composite material.

  Such first and second sheets 21 and 22 are prepared, and both are folded in a direction orthogonal to the stretching direction. In FIG. 1, the folds 21a and 22a when folded in two are indicated by broken lines. As shown in FIG. 2, the power generation element 2 is housed in the center of the first sheet 21 folded in half. At that time, the high-power tabs 15 and 16 are taken out by folding the fold 21a so that the drawing direction of the first sheet 21 and the take-out direction of the high-power tabs 15 and 16 (left-right direction in FIG. 2) are parallel. It should be on the side opposite to the side. However, since FIG. 2 shows the state before the first sheet 21 is folded in two, the vicinity of the fold line 21a is shown in an expanded state.

  The reason why the fold line 21a of the first sheet is located on the side opposite to the side where the high-power tabs 15 and 16 are taken out is that the high-power tabs 15 and 16 are taken out. That is, when the fold line 21a is located on the same side as the side from which the high-power tabs 15 and 16 are taken, there is an operation for processing the opening hole for taking out the high-power tabs 15 and 16 to the outside of the battery into the first sheet 21. This is because it is additionally required. On the other hand, when the fold line 21a is located on the side opposite to the side from which the high voltage tabs 15 and 16 are taken out, the ends 21b and 21c opposite to the fold line 21a are open ends. The process of processing the opening hole for taking out outside becomes unnecessary. If this work is allowed, the fold line 21a may be arranged on the same side as the side to which the high voltage tabs 15 and 16 are attached.

  In addition, the size of the first sheet 21 is selected so that the periphery of the first sheet 21 is in the same position as the periphery of the power generation element 2 with the first sheet 21 in close contact with the power generation element 2. To do.

  Next, as shown in FIG. 3, the second sheet 22 that is folded in half on the outer side of the first sheet 21 that is in close contact with the power generation element 2 is covered. At that time, the extending direction of the second sheet 22 and the taking-out direction of the high voltage tabs 15 and 16 are set to be orthogonal to each other. As a result, the extending direction of the first sheet 21 and the extending direction of the second sheet 22 are orthogonal to each other.

  Since FIG. 3 also shows a state before the second sheet 22 is folded in two, the vicinity of the fold line 22a of the second sheet is shown in a swelled state. FIG. 3 shows a state in which the second sheet 22 can be seen through in order to clarify the positional relationship between the second sheet 22 and the first sheet 21.

  In addition, the second sheet 22 is placed in the same position as the periphery of the power generation element 2 with the second sheet 22 in close contact with the first sheet 21 and the power generation element 2. A size of 22 is selected.

  The first and second sheets 21 and 22 function as protective sheets for the power generation element 2. For example, when it is assumed that the external force A in the horizontal direction acts on the side surface of the power generation element 2 from the side opposite to the side from which the high power tabs 15 and 16 are taken out as shown in FIG. The vicinity of the fold line 21 a of the first sheet 21 receives the external force A and dents inside. Thereby, the energy of the external force A can be absorbed, and the external force A can be prevented from acting directly on the side surface of the power generation element 2. Further, when it is assumed that the external force B in the horizontal direction acts on the side surface of the power generating element 2 from the side next to the side where the high power tabs 15 and 16 are taken out as shown in FIG. The second sheet 22 receives the external force B and dents inside. Thereby, the energy of the external force B can be absorbed, and the external force B can be prevented from acting directly on the side surface of the power generation element 2.

  Further, as shown in FIG. 3, when it is assumed that the external force C in the vertical direction acts on the outermost layer portion of the battery element from vertically above, the first and second sheets 21 and 22 are external force C against the external force C. And dent inside. As a result, the energy of the external force c is absorbed, and the external force C can be prevented from directly acting on the outermost layer portion of the power generation element 2.

  Thus, the manufacturing method of the battery 1 after the 1st, 2nd sheet | seats 21 and 21 are piled up on the electric power generation element 2 and coat | covered it adhere | attach is the same as the conventional apparatus. That is, the power generation element 2 in which the two sheets 21 and 21 are overlapped and adhered to the power generation element 2 and the peripheral portions (peripheral portions) 14a to 14d of the four sides are heat-sealed using a laminate film. The power generation element 2 is housed and sealed by joining at (see FIG. 5). The high voltage tabs 15 and 16 are led out of the laminate film 14 so as to be sandwiched between the ends of the laminate film 14. The high voltage tabs 15 and 16 are ultrasonically welded to the negative electrode current collector 5 and the positive electrode current collector 9 of each electrode via a positive electrode terminal lead (not shown) and a negative electrode terminal lead (not shown) as necessary. Or it may be attached by resistance welding.

  As another form of the lithium ion secondary battery, a bipolar electrode in which a positive electrode active material layer is formed on one surface of a current collector and a negative electrode active material layer is formed on the other surface through a separator. A stacked bipolar secondary battery can be mentioned. The battery 1 and the bipolar secondary battery are basically the same except that the electrical connection state (electrode structure) in both batteries is different. The present invention also applies to this bipolar secondary battery.

  A battery having a predetermined voltage is obtained by laminating and storing the laminated battery 1 configured as described above in a metal battery case, and connecting the plurality of laminated laminated batteries 1 in series using each high voltage tab. A pack is composed. Furthermore, an assembled battery having a predetermined voltage is configured by electrically combining a plurality of battery packs, and this assembled battery is mounted on a transportation facility such as an electric vehicle or a hybrid vehicle.

  Here, the function and effect of the first embodiment will be described.

  According to 1st Embodiment, the 1st, 2nd sheet | seats 21 and 22 comprised from the electric power generation element 2 which laminated | stacked the negative electrode 4, the separator 12, and the positive electrode 8 in this order and the resin porous body which has an extending | stretching direction. The first and second sheets 21 and 22 covering the entire power generating element 2 so that the extending direction of the first sheet 21 and the extending direction of the second sheet 22 intersect each other are covered. Since it is provided, the outermost layer part of the power generation element 2 and the side surface of the power generation element, which are structurally weak against external force, can be protected from the external force. For example, when the power generation element 2 is placed with the stacking direction in the vertical direction, the two outermost layers (upper and lower surfaces) in the stacking direction of the power generation element 2 are two sheets 21 having different stretching directions, Since 22 is covered and overlapped, it is strong on the surface. On the other hand, the side surface of the power generation element 2 covered with a sheet having the stacking direction as the extending direction is strong against external force from the horizontal direction toward the side surface. As a result, it is possible to prevent a tension from acting locally on a portion where the ability to receive force is weak, and the separator 12 is torn and the positive electrode 8 and the negative electrode 4 are in direct electrical contact and short-circuited. The reliability (safety) of the battery 1 can be greatly improved.

  According to the first embodiment, since the angle at which the stretching direction of the first sheet 21 and the stretching direction of the second sheet 22 intersect is 90 degrees, the external force is efficiently absorbed only by the two sheets 21 and 22. can do.

  According to the first embodiment, the negative electrode 4, the separator 12, and the positive electrode 8 are laminated in one direction to form a rectangular flat shape having four sides as a whole, and the high voltage tab 15 connected to the negative electrode 4 and the positive electrode 8 are connected. The strong electric tabs 16 to be taken out from one side of the four sides are taken out together, and the high electric tabs 15 and 16 are taken out between the first sheet 21 folded in the direction perpendicular to the stretching direction and the two folded sides. The power generation element 2 is accommodated so as to be on the side opposite to the side, and on the outside of the first sheet 21 so that the extending direction of the first sheet 21 and the extending direction of the second sheet 22 are orthogonal to each other. Since the second sheet 22 is covered, there is no need to open a hole for penetrating the high voltage tabs 15 and 16 in the first sheet 21 and workability is improved.

  In the first embodiment, the angle at which the stretching direction of the first sheet 21 and the stretching direction of the second sheet 22 intersect with each other is 90 degrees. However, the angle is not necessarily 90 degrees. Any angle close to degrees is acceptable.

In 1st Embodiment, although demonstrated in the case of the resin porous body sheet manufactured by the uniaxial stretching method, it is not restricted to this.
The uniaxial stretching method produces a resin porous sheet by stretching in one direction only in the X direction, but there is a method for producing a resin porous sheet by stretching in two methods in the X and Y directions. (See JP 2004-31097 A). The Y direction is a direction orthogonal to the X direction.

  In this case, the strength of stretching in two different directions often has strengths. That is, the biaxial stretching direction of the first stretching direction (for example, the X direction) in which relatively strong stretching is applied and the second stretching direction (for example, in the Y direction) in which relatively weak stretching is applied is defined as a resin porous material. The body sheet will have. In the case of the first and second sheets composed of the porous resin sheet having such biaxial stretching directions, the direction in which relatively strong stretching is applied may be considered as a reference. That is, the entire power generating element may be covered so that the first stretching direction of the first sheet intersects the first stretching direction of the second sheet. The angle formed by the two axes is not limited to 90 degrees, and may be in the range of 0 degrees to 90 degrees (excluding 0 degrees).

  Next, in the first embodiment, the case where the number of the first sheet 21 is one and the number of the second sheet 22 is one is two, but the number is not necessarily two. For example, from the state where the power generation element 2 is covered with the first and second sheets 21 and 22 (see FIG. 3), the third sheet 23 may be covered with the third sheet 23 on the outer side. It doesn't matter.

  This will be described. FIG. 6 is a schematic perspective view of the second embodiment showing a state in which the power generating element 2 is covered with the first, second, and third sheets 21, 22, and 23. FIG. Since FIG. 6 also shows a state before the third sheet 23 is folded in two, the vicinity of the fold line 23a of the third sheet is shown in an expanded state. In FIG. 6, a state in which the third sheet 23 can be seen through is shown in order to clarify the positional relationship between the third sheet 23 and the second sheet 22.

  Unlike the first and second sheets 21 and 22, the third sheet 23 extends in the direction perpendicular to the longitudinal direction (vertical direction in FIG. 7) as shown in FIG. 7. Such a third sheet 23 is prepared and folded in half at the center. In FIG. 7, the fold line 23a when the sheet is folded in two is indicated by a broken line. Then, from the state in which the power generation element 2 is covered with the first and second sheets 21 and 22 (see FIG. 3), the third sheet 23 is further covered as shown in FIG.

  With this configuration, even when the external force B in the horizontal direction acts on the side surface of the power generation element 2, the two sheets 22 and 23 having different stretching directions are covered and covered on the side surface. It has become strong. As a result, the two sheets 22 and 23 absorb the energy of the external force B, and the external force B can be prevented from acting directly on the side surface of the power generation element 2.

  In the second embodiment, the total number of sheets is three so that not only the upper and lower surfaces of the power generation element 2 but also the side surfaces of the power generation element 2 are covered with two sheets having different stretching directions. I was able to. Therefore, when the number of sheets is three or more as a whole, not only the upper and lower surfaces of the power generation element 2 but also other aspects of covering the side surfaces of the power generation element 2 with two sheets having different stretching directions are considered. obtain.

  In the embodiment, the laminated battery has been described. However, the present invention is not limited to the laminated battery. If the electric device has a power generation element including a negative electrode, a separator, and a positive electrode, the power generation element is covered with an exterior body that is structurally weak against an external force such as a resin. For this, the present invention is applicable.

1 Laminated battery (electric device)
4 Negative electrode 5 Negative electrode current collector 6 Negative electrode active material layer 8 Positive electrode 9 Negative electrode current collector 10 Positive electrode active material layer 12 Separator 14 Laminate film 15, 16 High voltage tab 21 First sheet 21a Fold 22 Second sheet 22a Fold 23 3 sheet 23a crease

Claims (8)

A power generation element in which a negative electrode, a separator, and a positive electrode are laminated in this order;
It is the 1st, 2nd sheet | seat comprised from the resin porous body which has a uniaxial stretching direction, Comprising: The said electric power generation so that the extending | stretching direction of a 1st sheet | seat and the extending | stretching direction of a 2nd sheet | seat may cross An electrical device comprising: a first sheet and a second sheet that cover the entire element.   The electrical device according to claim 1, wherein an angle at which the stretching direction of the first sheet intersects the stretching direction of the second sheet is 90 degrees. By laminating the negative electrode, separator and positive electrode in one direction, the power generation element as a whole is formed into a square flat shape having four sides,
While taking out the high power tab connected to the negative electrode and the high power tab connected to the positive electrode together from one side of the four sides,
Storing the power generation element between the first sheet folded in two in a direction perpendicular to the stretching direction, and the side folded in two is on the side opposite to the side from which the high voltage tab is taken out;
The said 2nd sheet | seat is coat | covered on the outer side of a said 1st sheet | seat so that the extending | stretching direction of a said 1st sheet | seat and the extending | stretching direction of a said 2nd sheet | seat are orthogonally crossed. Electrical devices. A power generation element in which a negative electrode, a separator, and a positive electrode are laminated in this order;
A first and second resin composed of a porous resin body having a biaxial stretching direction of a first stretching direction with relatively strong stretching and a second stretching direction with relatively weak stretching. First and second covering the entire power generating element so that the first extending direction of the first sheet and the first extending direction of the second sheet intersect each other. An electrical device comprising:   The electrical device according to claim 4, wherein an angle at which the first stretching direction of the first sheet intersects the first stretching direction of the second sheet is 90 degrees. By laminating the negative electrode, separator and positive electrode in one direction, the power generation element as a whole is formed into a square flat shape having four sides,
While taking out the high power tab connected to the negative electrode and the high power tab connected to the positive electrode together from one side of the four sides,
The power generating element is disposed between the first sheet folded in a direction orthogonal to the first stretching direction, and the folded side is on the side opposite to the side from which the high-voltage tab is taken out. Stow and
The second sheet is coated on the outer side of the first sheet so that the first stretching direction of the first sheet and the first stretching direction of the second sheet are orthogonal to each other. The electrical device according to claim 4 .   The electrical device according to claim 3 or 6, wherein the total number of the sheets is at least three.   5. The electric device according to claim 1, further comprising a laminate film that covers the entire battery element covered with the first and second sheets as an exterior body. 6.

Images