JP2013069571A - Sealed secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealed secondary battery capable of preventing leakage from a liquid injection port.SOLUTION: The sealed secondary battery in one embodiment is characterized by including a battery container having the liquid injection port in which an electrolyte can be injected, and a liquid holding part arranged so that fluid can be held in a region apart from the liquid injection port and a drainage part arranged so that fluid can be guided so as to be evacuated from the liquid injection port are provided in a periphery of and apart from the liquid injection port in an inner surface of the battery case.

Description

  Embodiments described herein relate generally to a sealed secondary battery.

  Sealed secondary batteries such as lithium ion batteries are widely used in portable electronic devices and the like. A sealed secondary battery includes, for example, a battery container including a metal container having an upper end opened and a metal sealing lid that is welded so as to close the opening of the container, and the sealing lid is welded to the container. Before, the battery element is placed in the container, and then the sealing lid is welded to the container to form a sealed battery container. Next, an electrolytic solution is injected into the battery container through a liquid injection port formed in the sealing lid. And after injection | pouring of electrolyte solution, a liquid inlet is sealed with a sealing body in a pressure-reduced environment.

JP 2000-106155 A

  In the above structure, electrolyte droplets adhere to the inner surface of the sealing lid, and when the liquid inlet is sealed with a sealing body under reduced pressure, the inner liquid passes through the liquid inlet due to a pressure difference. May leak outside. In addition, when the meniscus force of the liquid is greater than the gravity, the liquid may crawl up the liquid inlet and leak.

  In the embodiment, a sealed secondary battery capable of preventing leakage from a liquid inlet is provided.

  A sealed secondary battery according to an embodiment has a liquid injection port configured to be able to inject an electrolyte, and in a region around the liquid injection port on the inner surface and away from the liquid injection port, A liquid holding part configured to hold the liquid in the region away from the liquid injection port, and a liquid discharge unit configured to be guided to retract the liquid from the liquid injection port on the inner surface are provided. The battery container is provided.

1 is a perspective view showing a partially closed sealed secondary battery according to an embodiment. The top view which shows the back surface side of the sealing lid of the sealed secondary battery. The top view which shows the structure of the liquid removal part of the sealing lid. Sectional drawing which shows the structure of the liquid inlet vicinity of the sealing lid. Explanatory drawing which shows the AA cross section in FIG. 2 of the drainage part of the same liquid removal part. Explanatory drawing which shows the BB cross section in FIG. 2 of the liquid holding | maintenance part of the same liquid removal part. The top view which shows the structure of the liquid removal part concerning other embodiment. The top view which shows the structure of the liquid removal part concerning other embodiment. Sectional drawing which shows the structure of the drainage part concerning other embodiment.

  Hereinafter, a sealed secondary battery 10 according to an embodiment will be described with reference to FIGS. 1 to 6. In each drawing, the configuration is schematically shown by appropriately enlarging, reducing, or omitting the configuration. FIG. 1 is a perspective view showing a partially closed sealed secondary battery 10 according to the present embodiment.

  As shown in FIG. 1, a sealed secondary battery 10 includes a flat box-shaped battery container 11 formed of a metal such as aluminum, and an electrode body 13 is placed in the battery container 11 together with an electrolyte. Contained.

  The battery container 11 includes a container 11A having an open upper end and a rectangular plate-shaped sealing lid 11B that seals the opening of the container 11A. The sealing lid 11B is placed on the end face of the opening of the container 11A and welded all around, thereby sealing the opening of the container 11A. Thereby, the container 11A and the sealing lid 11B are integrated with no gap to form the sealed battery container 11.

  A positive terminal 14 and a negative terminal 15 are provided at both ends in the longitudinal direction of the sealing lid 11B so as to protrude from the sealing lid 11B. The positive electrode terminal 14 and the negative electrode terminal 15 are connected to the positive electrode and the negative electrode of the electrode body 13, respectively. A thin portion 16 is formed between the positive electrode terminal 14 and the negative electrode terminal 15 so as to be broken when gas is generated and the pressure inside the battery increases.

  A liquid injection port 17 for injecting an electrolytic solution into the battery container 11 is formed through the central portion of the sealing lid 11B. The liquid injection port 17 is formed in a circular shape, for example. The liquid injection port 17 is sealed by a sealing body 19 fixed to the sealing lid 11B.

  The sealing body 19 is formed in a disk shape with, for example, aluminum, and has a thickness substantially equal to the depth of the sealing lid 11B. The sealing body 19 is welded to the sealing lid 11B by laser welding. As the electrolytic solution, a material having a higher viscosity than water and a small surface tension is used.

  The electrode body 13 is formed in a flat shape by, for example, winding a positive electrode plate and a negative electrode plate in a spiral shape with a separator interposed therebetween, and further compressing in a radial direction.

  FIG. 2 is a plan view showing an inner surface (back surface) of the sealing lid 11B, and FIG. 3 is a plan view showing a configuration of the liquid removal unit. As shown in FIG. 2, a liquid removal unit 20 is provided in a region A1 around the liquid injection port 17 on the inner surface of the sealing lid 11 </ b> B and spaced from the liquid injection port 17. The region A1 is an annular region surrounded by, for example, a circle separated from the liquid injection port 17 by a predetermined distance (for example, 3 mm) and a circle separated by a predetermined distance (for example, 20 mm). The liquid removal unit 20 includes a liquid holding unit 22 and a liquid discharge unit 21. The liquid removal unit 20 is arranged so as not to come into contact with various components installed inside the sealed battery 10.

  FIG. 4 is a cross-sectional view showing a configuration in the vicinity of the liquid injection port 17 of the sealing lid 11, and FIG. 5 is an explanatory diagram showing a configuration of the drainage part 21. The drainage part 21 is arranged around the liquid injection port 17 with a certain distance from the liquid injection port 17. The drainage part 21 is composed of a plurality of transport paths 25 that are provided radially from a place away from the liquid injection port 17 by a predetermined distance. Each transport path 25 has, for example, a pair of raised portions 26 and 26 (protrusions), and a liquid is guided and transported in the separating direction by capillary action at a portion sandwiched between the raised portions 26 and 26. For example, the raised portions 26 are formed by creating a bead-on state by laser irradiation. At this time, the heights of the raised portions 26 and 26 are determined by the heat input of the laser to the material. For example, here, the width of the transport path 25 is 0.5 mm to 1 mm, and the height is 0.1 mm to 1 mm.

  In the transport path 25, the inner end is at an inner position closer to the liquid injection port 17 than the liquid holding unit 22, and the outer end is at an outer position farther from the liquid injection port 17 than the liquid holding unit 22. It has been formed. The transport path 25 is configured to transport the liquid along the pair of raised portions 26 and 26 using capillary action. When a droplet adheres in the vicinity of the liquid injection port 17, the liquid surface located in the direction perpendicular to the wall surface of the transport path 25 is directed toward reducing the interfacial energy by capillary action. That is, force acts so that the liquid level becomes flat, and the electrolytic solution proceeds along the transport path 25. At this time, the shape of the transport path 25 is determined according to the relationship between the contact angle of the liquid, that is, the surface tension of the liquid and the area of the wall in contact with the liquid. Here, various dimensions are determined using an equation for evaluating the capillary phenomenon in the case of a tube. The rising height of the liquid level is expressed as h = 2T cos .g r .., h is the height of the liquid level, T is the surface tension, .. is the contact angle, .. is the density of the liquid, g Is the acceleration of gravity, and r is the inner diameter (radius) of the tube. On the wall, the surface tension and the interfacial tension of the wall are balanced. Various dimensions such as the height dimension, width, and curve shape of the transportation path are set to appropriate values depending on conditions such as surface tension, contact angle, liquid density, gravity acceleration, and inner diameter of the tube. Here, the width of the transport path 25 of the drainage part 21 was set to about 0.6 mm. The raised portions 26, 26 have a shape that protrudes larger on the outer side farther from the liquid injection port 17 than on the center side near the liquid injection port 17. That is, the area of the inner surface 26a of the transport path increases as the transport path 25 moves away from the liquid injection port 17, and the liquid is guided toward the outside. For example, the height h1 of the center side end portion is about 0.5 mm, and the height h2 of the end portion on the outer peripheral side is about 1.0 mm. For example, the height of the ridges 26 and 26 is adjusted by adjusting the laser irradiation energy when forming the ridges 26 and 26, and the height (depth) of the groove is adjusted.

  FIG. 6 is a cross-sectional view showing the configuration of the liquid holding unit. As shown in FIGS. 2, 3, and 6, the liquid holding unit 22 is formed around the liquid injection port 17 in a region A <b> 1 spaced apart from the liquid injection port 17 by a certain distance, and between the plurality of transport paths 25. In FIG. 4, the liquid overflowing from the transport path 25 is retained.

  The liquid holding part 22 forms a lyophilic region by alternately arranging a plurality of first portions 22b, second portions and 22a in a circular stripe shape around the liquid injection port 17 on the inner surface of the sealing lid 11B. Yes. Each modified region 22b has a width of about 0.2 mm and a pitch of about 0.4 mm.

  For example, surface modification by laser is used here. By forming a first portion 22a that is modified by melting the surface of the material on the inner surface of the sealing lid 11B by melting the surface and a second portion 22b that is not irradiated with the laser, a space between the material surface and the liquid is formed. Control interface free energy. For example, here, the first portion 22a is a laser-modified portion (surface is smooth), and the second portion 22b is an unmodified portion (surface is rough).

  As shown in FIG. 6, in the liquid holding part 22, the first portion 22a and the second portion 22b have different material surface roughness, resulting in a difference in interface energy between the liquid and the material surface. Since the liquid tends to spread in the direction where the surface becomes smooth after laser irradiation, the liquid-irradiated modified part and the non-modified part not irradiated with the laser are alternately formed into a stripe structure. The lyophilicity and the adsorption power to the surface are enhanced. That is, the liquid holding unit 22 is in a lyophilic state in which a plurality of regions having different interfacial energies are installed, so that the liquid is difficult to move even when it receives an external force.

  Hereinafter, the liquid removal operation of the sealed secondary battery according to the present embodiment will be described with reference to FIGS. The electrolyte droplet Q (liquid) adhering to the vicinity of the liquid injection port 17 is transported along the transport path 25 of the drainage part 21. In other words, due to capillary action, the liquid surface in contact with the inner surface (wall surface) of the transport path 25 is flattened in an attempt to reduce the interfacial energy, so that the liquid droplet Q near the liquid injection port 17 becomes the wall surface of the transport path 25. It moves outward along the line 25 a and retreats from the liquid injection port 17.

  As shown in FIG. 5, the droplet Q of the electrolyte overflowing from the transport path 25 moves to the liquid holding unit 22 formed in the surrounding area. As shown in FIG. 6, the liquid holding unit 22 is provided with a plurality of regions having different interfacial energies so as to be in a lyophilic state. The liquid is held in a region away from the mouth 17, and it is difficult for liquid to come out of the region (two-dimensional region). Therefore, by separating the electrolyte solution from the vicinity of the liquid injection port 17 at the drainage portion 21, the leakage of the electrolyte solution to the surface of the sealing lid 11 </ b> B is prevented, and the electrolyte solution is retained in the liquid holding portion 22 with an external force. It is possible to avoid the electrolytic solution from moving again to the injection port 17.

  In the sealed battery 10 using the battery container 11 as described above, for example, the electrode body 13 is accommodated in the container 11A, the sealing lid 11B is welded to the container 11A to close the opening of the container 11A, and the liquid injection port 17 After injecting the electrolytic solution, the sealing body 19 is welded so as to close the liquid injection port 17 in a reduced pressure environment.

  In the sealing lid 11B according to the present embodiment, the liquid droplet Q of the electrolytic solution is transported so as to be retracted from the liquid injection port 17 by the drainage unit 21 of the liquid removal unit 20, and is moved to the liquid injection port 17 side by the liquid holding unit 22. It does not move. For this reason, when the sealing lid 11B is installed in the liquid injection port 17 of the battery container 11 and hermetic joining is performed by laser welding in a reduced pressure environment, the electrolyte rises from the liquid injection port 17 and the vicinity of the electrolyte injection port 17 Can be prevented from entering. In addition, it is possible to provide a sealed secondary battery 10 having a structure in which a sealing plug is sealed by a dry process that does not use chemicals, and a method for manufacturing the same.

  Accordingly, the liquid injection port 17 of the battery container 11 is hermetically sealed by the sealing body 19. For this reason, the sealed battery 10 according to the present embodiment can provide laser welding sealing of the liquid injection port 17 having high reliability. In addition, by reducing laser welding defects at the liquid injection port 17, batteries can be manufactured with a high yield.

  In the above embodiment, the transport path 25 is configured by the pair of raised portions 26 and 26 formed by laser irradiation as the configuration of the transport path 25. However, the present invention is not limited to this. For example, as shown in FIG. 7, the inner surface of the sealing lid 11 </ b> B may be processed to form a groove 28, and the liquid may be transported along the groove 28.

  Moreover, although the example using the modification | reformation by laser processing was shown as a method of forming the liquid holding | maintenance part 22 (lyophilic area | region), it is not restricted to this. For example, modification by plasma (discharge treatment), modification by chemicals, modification by polishing, or the like may be used.

further,
Further, as shown in FIG. 8, the transportation path 25 may be guided radially while being curved. Further, as shown in FIG. 9, a short sub-transport path 29 may be separately formed between the plurality of transport paths 25. The sub transport path 29 has an end on the inner side (closer to the liquid injection port 17) of the liquid removal unit 20 disposed at a position closer to the liquid injection port 17 than the liquid holding unit 22, and an outer side (from the liquid injection port 17. The end portion on the side away is disposed in the region of the liquid holding portion 22. In this embodiment, the liquid in the vicinity of the liquid injection port 17 is more reliably transported by the sub-transport path 29 and retracted by the liquid discharge part 21, and is retained in the liquid holding part 22, thereby improving the liquid leakage prevention effect. Is possible.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  A1 ... area, 10 ... sealed secondary battery (battery), 11 ... battery container, 11A ... container, 11B ... sealing lid, 11B ... sealing lid, 13 ... electrode body, 14 ... positive electrode terminal, 15 ... negative electrode terminal, 17 DESCRIPTION OF SYMBOLS ... Liquid injection port, 19 ... Sealing body, 20 ... Liquid removal part, 21 ... Drainage part, 22 ... Liquid holding part, 24 ... Modification | reformation area | region, 25 ... Transport path (transport path), 25a ... Wall surface, 26 ... Raised part, 28 ... groove, 29 ... sub-transport route.

Claims (5)

  A liquid injection port configured to be able to inject an electrolyte solution, and a liquid in a region around the liquid injection port on the inner surface thereof and away from the liquid injection port. A sealed secondary battery comprising a battery container provided with a liquid holding portion configured to be able to hold, and a drainage portion that guides liquid on the inner surface and retreats from the liquid injection port . The liquid holding part is configured to have a plurality of regions having different surface roughness around the liquid inlet,
The drainage portion extends in a direction away from the liquid injection port from a position closer to the liquid injection port than the liquid storage holding portion on the inner surface of the battery container, and the liquid injection port on the inner surface due to capillary action. The sealed secondary battery according to claim 1, further comprising a transport path for guiding the liquid adhering to the vicinity. A plurality of the transport paths are formed radially from the liquid injection port,
The liquid holding portion is provided in a region surrounding the liquid injection port in the vicinity of the liquid injection port that is separated from the liquid injection port, and a 22nd portion different from the first surface roughness and the first portion of the first surface roughness. 3. The sealed secondary battery according to claim 2, wherein the second surface roughness portions are alternately arranged in a stripe pattern.   The sealed secondary battery according to claim 3, wherein the transport path is configured such that an area of the transport inner surface increases with distance from the liquid injection port. The battery container includes a container having an opening, and a sealing lid that closes the opening of the container,
The liquid inlet is provided in the sealing lid and the liquid holding part and the drainage part are formed in a region around the liquid inlet,
The electrode body is accommodated in the container, the sealing lid is welded to the container to close the opening of the container, the electrolyte is injected from the liquid inlet, and then the liquid inlet is closed under a reduced pressure environment. The sealed secondary battery according to claim 1, wherein the sealed secondary battery is manufactured by welding a sealing body to the battery.

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