JP5062463B2 - Square battery case and square battery - Google Patents

Description

  The present invention relates to a prismatic battery case excellent in safety and a prismatic battery using the prismatic battery case. The present invention relates to a prismatic battery case and a prismatic battery having features.

  Batteries are desired to have high energy density and high output, and batteries with high energy density are provided. Since these batteries have a high energy density, there is a possibility that a problem such as a large amount of gas is generated in the battery when a certain problem (such as a short circuit) occurs in the battery. For this purpose, a gas vent valve is provided in order to achieve both airtightness during normal operation and gas exhaustability when an abnormality occurs (Patent Documents 1 to 3, etc.).

  As an example of the positional relationship between the wound electrode body and the gas vent valve in the conventional rectangular battery case, as shown in FIG. 8, the prismatic battery case main body 93, the lid 92, and the gas vent provided in the lid 92 The structure which has the valve 94 is mentioned. In the rectangular battery shown in FIG. 8A, the winding axis of the wound electrode body 91 is orthogonal to the direction in which the wound electrode body 91 is inserted into the rectangular battery case main body 93 (that is, the opening direction). It is oriented in the direction (XX ′ direction). In the rectangular battery shown in FIG. 8B, the winding axis of the wound electrode body 91 ′ is parallel to the direction in which the wound electrode body 91 ′ is inserted into the rectangular battery case main body 93 (ZZ ′). The gas vent valve 94 provided on the lid 92 is provided at a position facing the winding surface 95 ′.

  And as shown in FIG. 9, the structure which has the square battery case main-body part 93 ', the cover body 92', and the gas vent valve 94 'provided in the square battery case main-body part 93' is mentioned. In the rectangular battery shown in FIG. 9, the winding axis of the wound electrode body 91 is orthogonal to the direction in which the wound electrode body 91 is inserted into the rectangular battery case main body 93 (that is, the opening direction) (X -X 'direction). The gas vent valve 94 ′ is provided on a surface facing the winding surface 95.

  Here, a case where an abnormality occurs in the prismatic battery, such as a short circuit, and gas is generated from the wound electrode bodies 91 and 91 ′ in the prismatic battery case will be described. First, the rectangular battery shown in FIG. 8A will be described. The generated high-temperature gas is ejected from the winding surface 95 of the wound electrode body 91 along the winding axis in the blowing X-X ′ direction. After the jetted gas hits the side surface of the rectangular battery case main body 93, it passes between the rectangular battery case main body 93 and the wound electrode body 91, reaches the lid 92, and degassed by opening the pressure. It ejects from the valve 94 to the outside.

  The rectangular battery shown in FIG. 8B will be described. The generated high-temperature gas is ejected from the winding surface 95 'of the wound electrode body 91' along the winding axis in the blowing Z-Z 'direction. The ejected gas reaches the lid 92 side, and is ejected to the outside from a gas vent valve 94 that opens due to a pressure increase.

  The square battery shown in FIG. 9 will also be described. The generated high-temperature gas is ejected from the winding surface 95 of the wound electrode body 91 in the direction of blowing X-X ′ along the winding axis. The ejected gas reaches the side surface of the rectangular battery case main body 93 ′, and is ejected to the outside from the degassing valve 94 ′ that opens due to the pressure increase.

The discharge gas is discharged from the gas vent valves 94 and 94 ′, so that the rectangular battery case main bodies 93 and 93 ′ and the lid bodies 92 and 92 ′ are not damaged, and the gas is discharged in the direction assumed from the gas vent valves 94 and 94 ′. Can be injected and discharged.
JP-A-7-296790 JP-A-6-283393 Japanese Patent No. 3015667

  However, in the prismatic battery shown in FIG. 8A, the distance from the winding surface 95 to the gas vent valve 94 is long, and it is difficult to secure the cross-sectional area of the gas flow path. There is a risk that the battery will not flow and the internal pressure of the battery will rise, sometimes leading to explosion. In addition, when the ejected gas does not flow smoothly, it is conceivable that the prismatic battery case body 93 is softened and melted at the side surface of the prismatic battery case body 93 that is directly exposed to the high-temperature gas.

  In the prismatic battery shown in FIG. 8B or FIG. 9, the wound electrode body 91 or 91 ′ may move to the gas vent valve 94 or 94 ′ side due to the reaction force at the time of gas generation. In this case, the high temperature gas may not be discharged satisfactorily.

  In order to solve this problem, it is conceivable to form the gas vent valve 94 or 94 ′ on both surfaces of the winding surface 95 or 95 ′ of the electrode body 91 or 91 ′, but the configuration of the gas vent valve is plural. Therefore, in addition to increasing the cost, the degassing valve needs to be handled with care in order to achieve both ease of opening during emergency and sealing during normal use, and the assembly process becomes very complicated.

  The present invention has been completed in view of the above circumstances, and a problem to be solved is to provide a prismatic battery case capable of realizing a prismatic battery excellent in safety with a simple configuration and a prismatic battery employing the prismatic battery case. And

  (1) The rectangular battery case of the present invention is a rectangular battery case in which a wound electrode body in which a belt-like positive electrode plate and a negative electrode plate are wound in a spiral shape via a belt-like separator is housed.

  (A) The rectangular battery case of the present invention that solves the above-mentioned problems is characterized in that the surface of the battery case facing the winding surface of the wound electrode body is thicker than the other surfaces.

(B) In addition, another rectangular battery case of the present invention that solves the above-described problems is provided with the winding surface between the surface of the battery case facing the winding surface of the wound electrode body and the winding surface. It has the shielding member which has the shape which covers all. Then, the shielding member is, in order not to conduct heat, even One gaps between the surface facing the wound surface. The shielding member is preferably not electrically connected to either the positive electrode plate or the negative electrode plate of the wound electrode body. Further, in order to reduce the number of parts it is, as the shielding member, it is desirable to also serve as the electrically connected conductive path to one of the positive electrode plate or the negative electrode plate of the wound electrode body.

  That is, it corresponds to the injection of the high temperature gas by improving the heat capacity and / or strength of the portion facing the winding surface from which the gas is ejected when an abnormality occurs. Since the part where the high-temperature gas is directly injected is only thickened or a shielding member is provided, the amount of material increase is small compared to the case where the overall thickness of the rectangular battery case is increased. The effect on energy density reduction and cost increase is negligible.

  The “winding surface” is a surface at both ends of the winding shaft around which the belt-like positive and negative electrodes are wound, and is a surface on which the overlapping of the positive and negative electrodes can be observed from the outside. Accordingly, the winding surface is a surface from which gas generated inside the winding electrode body is first ejected through the gap.

  In particular, in a normal state, the inside and outside of the battery case is kept sealed, and a gas vent valve that opens when the internal pressure of the battery case reaches a predetermined value or more is provided on a surface that does not face the winding surface of the wound electrode body. It is desirable to employ a configuration to provide. As described above, if a gas vent valve is formed in the portion facing the winding surface, the wound electrode body may move due to gas injection and block the gas vent valve. This is because the provision on the surface not facing the surface eliminates the possibility of closing the gas vent valve even if the wound electrode body moves.

  (2) The prismatic battery of the present invention that solves the above problems is housed in the prismatic battery case of the present invention described above and the prismatic battery case, and the strip-shaped positive electrode plate and the negative electrode plate are spirally arranged through the strip-shaped separator. And a wound electrode body wound around.

  Since the prismatic battery case of the present invention has the above-described configuration, it exerts the following effects when applied to a prismatic battery. That is, even if hot gas may be generated from the wound electrode body in the event of an abnormality, the heat capacity and strength of the portion where the hot gas is directly injected are increased, so a rectangular battery case with the same mass The risk of being destroyed can be made very small.

  In addition, by providing a gas vent valve as described above, the internal pressure of the rectangular battery case can be blocked by closing the gas vent valve even if the wound electrode body moves, such as when the amount of high-temperature gas generated is large. Can be effectively prevented from increasing.

  The rectangular battery case of the present invention will be described below based on the embodiments. The prismatic battery case of this embodiment is a prismatic battery case that houses therein a wound electrode body in which a strip-like positive electrode plate and a negative electrode plate are spirally wound via a strip-like separator. The prismatic battery to which the prismatic battery case of the present embodiment can be applied is not particularly limited as long as the electrode body in which the battery reaction proceeds is a wound type. In particular, it is effective to apply to a battery having a high energy density. For example, it can be applied to a lithium secondary battery or an electric double layer capacitor.

  (A) The surface facing the winding surface of the wound electrode body of the battery case is thicker than the other surfaces. As shown in FIG. 1, the prismatic battery including the prismatic battery case of the present embodiment includes a configuration having a prismatic battery case main body 13, a lid 12, and a gas vent valve 14 provided on the lid 12. . Then, after inserting the wound electrode body 11 so that the center line XX ′ of the winding axis is parallel to the opening of the rectangular battery case main body 13, the opening of the rectangular battery case main body 13 is covered with the lid. A rectangular battery is formed by closing and welding at 12.

  In the rectangular battery shown in FIG. 1, the winding axis of the wound electrode body 11 is orthogonal to the direction (that is, the opening direction) in which the wound electrode body 11 is inserted into the rectangular battery case body 13 (X direction). -X 'direction).

  Here, as shown in FIG.1 (b), as for the square battery case main-body part 13, the surfaces 13a and 13b which the winding surface 15 of the winding type electrode body 11 opposes are thicker than another surface. The method for changing the wall thickness depending on the surface is not particularly limited. For example, when manufacturing the rectangular battery case of the present embodiment by multi-stage deep drawing, the mold shape is changed and the surfaces other than the surfaces 13a and 13b are gradually stretched and thinned. A rectangular battery case with thickened surfaces 13a and 13b can be realized. It can also be easily manufactured by assembling members having different thicknesses by welding or the like.

  Here, a case where an abnormality occurs in the rectangular battery, such as a short circuit, and gas is generated from the wound electrode body 11 in the rectangular battery case will be described. The generated high temperature gas is ejected from the winding surface 15 of the wound electrode body 11 along the winding axis X-X ′. The ejected gas comes into contact with the side surfaces 13a and 13b of the rectangular battery case main body 13 and then passes between the rectangular battery case main body 13 and the wound electrode body 11 to reach the vicinity of the lid 12 and is opened due to pressure increase. The gas vent valve 14 is ejected to the outside. Since the surfaces 13a and 13b are thicker than the other surfaces, the heat capacity and strength are improved, and there is little risk of being softened or broken even when high-temperature gas is directly injected.

(simulation)
In the prismatic battery shown in FIG. 1, when a rectangular battery case having a short side direction of 20 mm, a long side direction of 100 mm, and a depth direction of 100 mm is employed, the thickness of the surfaces 13a and 13b and the other thicknesses The temperature change when the thickness of the surface was changed was examined by simulation. The calculation was performed under the condition of heating at 190 W for 4 seconds assuming a heating element of 15 mm × 15 mm in the center of the surface 13a.

  The calculation was performed assuming that the rectangular battery case was made of aluminum (melting point: 660 ° C.), the thickness of the surface 13a was changed from 0.5 mm to 1.5 mm, and the thickness of the other surfaces was 0.5 mm. The strength of the rectangular battery case was evaluated as being proportional to the tensile strength of the aluminum material. The results are shown in FIG.

  As apparent from FIG. 2, when the thickness is 0.5 mm, the maximum temperature is 400 ° C., and the strength is reduced to 8% of the normal temperature. By increasing the wall thickness to 0.8 mm, the maximum temperature can be suppressed to 280 ° C, and the strength can be 27% of normal temperature and more than three times the strength when the wall thickness is 0.5 mm. Is possible. Further, when the thickness is increased to 1 mm, the maximum temperature can be reduced to 240 ° C., and the strength can be secured at 37% at room temperature and 5 times the strength at 0.5 mm thickness. Further, since there is an effect of improving the strength by increasing the thickness, it has been found that the strength at a high temperature can be remarkably improved by slightly increasing the thickness of the side surface of the housing.

  When the thickness of the surfaces 13a and 13b is increased from 0.5 mm to 0.8 mm under the above-mentioned conditions, the volume increase of the battery is about 0.6%, which is almost negligible. The strength can be increased to three times or more, and the strength of the housing at high temperature can be remarkably improved without impairing downsizing.

  As described above, by making only the thickness of the surfaces 13a and 13b thicker than the other surfaces, it is possible to suppress the temperature rise of the surfaces 13a and 13b that are directly exposed to the gas generated inside the battery case at the time of abnormality and become the highest temperature. This can prevent softening and melting of the rectangular battery case. Therefore, a battery excellent in safety can be provided.

  (B) In this embodiment, a shielding member is provided between the surface of the battery case facing the winding surface of the wound electrode body and the winding surface. The shielding member is a member having a shape that covers the entire winding surface. Since the shielding member is a member that prevents the hot gas from coming into direct contact with the rectangular battery case from the winding surface, the shielding member has a shape that covers the entire winding surface where the hot gas may be jetted.

  It is preferable that the shielding member is not in contact with the rectangular battery case because heat from the shielding member that is heated by direct injection of high-temperature gas is difficult to conduct. And as a shielding member, it is desirable to employ | adopt the electrode terminal etc. which serve as the electrically conductive path electrically connected to either the positive electrode plate or negative electrode plate of a winding type electrode body from a viewpoint of a reduction in a number of parts.

  For example, as shown in FIG. 3, the electrode terminals 16 and 17 have a shape (FIG. 3 (b)) that covers the entire winding surface 15 of the wound electrode body 11, and the vicinity of the center in the vertical direction. Can be made to serve as a shielding member at the electrode terminals 16 and 17 by connecting to the wound electrode body 11 at the recessed portion. The electrode terminals 16 and 17 are disposed between the wound electrode body 11 and the rectangular battery case main body 13. Therefore, it is possible to prevent the high-temperature gas ejected when an abnormality occurs from coming into direct contact with the prismatic battery case main body 13. Further, since a gap is provided between the electrode terminals 16 and 17 and the winding surface, the ejected high-temperature gas can flow between the winding electrode body 11 and the electrode terminals 16 and 17, and the lid body. Thus, a flow path reaching the gas vent valve 14 provided at 12 can be ensured.

  Furthermore, even if the electrode terminal 16 or 17 is softened or melted, a gap is provided between the electrode case 16 and the prism battery case main body 13, so that the temperature rise is not transmitted directly, and the temperature of the prismatic battery case main body 13 is increased. Can be suppressed. Therefore, softening and melting of the rectangular battery case main body 13 can be prevented.

  In addition, shield members 181 to 184 provided independently of the electrode terminals 16 ′ and 17 ′ having various shapes as shown in FIGS. 4 to 7 may be employed.

  The shielding members 181 and 183 are combined with the electrode terminals 16 ′ and 17 ′ so as to cover the entire winding surface 15 of the wound electrode body 11. The shielding members 182 and 184 have a shape that covers all of the winding surface 15 of the wound electrode body 11 alone. The shielding members 181 and 183 are shaped so as to cover the lower surface side of the wound electrode body 11, and can more reliably protect the high temperature gas ejected when an abnormality occurs.

It is the assembly figure (a) and sectional drawing (b) of the square battery in an Example. It is a graph which shows the result of having performed simulation about the square battery in an example. It is sectional drawing of the square battery in an Example. It is sectional drawing of the square battery in an Example. It is sectional drawing of the square battery in an Example. It is sectional drawing of the square battery in an Example. It is sectional drawing of the square battery in an Example. It is the conventional assembly drawing (a) and sectional drawing (b). It is the conventional assembly drawing (a) and sectional drawing (b).

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Winding type electrode body 12 ... Cover body 13 ... Square battery case main-body part 14 ... Gas vent valve 15 ... Winding surface 16, 17, 16 ', 17' ... Electrode terminal (a part also serves as a shielding member)
181 to 184 ... shielding member

Claims (6)

A rectangular battery case that houses therein a wound electrode body obtained by winding a strip-shaped positive electrode plate and a negative electrode plate in a spiral shape through a strip-shaped separator,
A rectangular battery case, wherein a surface of the battery case facing a winding surface of the wound electrode body is thicker than other surfaces. A rectangular battery case that houses therein a wound electrode body obtained by winding a strip-shaped positive electrode plate and a negative electrode plate in a spiral shape through a strip-shaped separator,
Have a shielding member having a shape to cover all the winding times surface between the wound electrode body winding face the battery case surface and the winding times surface opposed to the,
The shielding member is a rectangular battery case having a gap between a surface facing the winding surface .   The prismatic battery case according to claim 2, wherein the shielding member is not electrically connected to either the positive electrode plate or the negative electrode plate of the wound electrode body. The rectangular battery case according to claim 2, wherein the shielding member also serves as a conductive path electrically connected to either the positive electrode plate or the negative electrode plate of the wound electrode body.   A degassing valve that is provided on a surface that does not face the winding surface of the wound electrode body, keeps the inside and outside of the battery case sealed in a normal state, and opens when the internal pressure of the battery case reaches a predetermined value or more. The prismatic battery case according to any one of claims 1 to 4.   The rectangular battery case according to any one of claims 1 to 5, and a wound electrode body housed in the rectangular battery case and wound in a spiral shape with a belt-like positive electrode plate and a negative electrode plate interposed via a belt-like separator A prismatic battery comprising:

Images