Lid Assembly and Battery

Abstract

According to an embodiment, a lid assembly is provided. The lid assembly is provided with a plate-shaped lid and a pair of terminals. The lid is attached to an opening of an exterior container housing an electrode group, and has a front surface and a back surface. The pair of terminals each have conductivity, and are disposed from the front surface side with respect to the lid while being separate in a state of being electrically insulated from each other. The lid is provided with a solution pouring port that penetrates from the front surface to the back surface of the lid between the pair of terminals. A recessed portion or a protruding portion is provided in at least a part of an area between the pair of terminals on the back surface of the lid.

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION Embodiments of the present invention relate to a lid assembly and a battery. [Background technology]

[0002] For example, a battery is formed by assembling components such as a lid assembly, an outer container, and an electrode group, which are distributed separately. In order to obtain a larger capacity power source, a battery pack (battery assembly) in which multiple batteries are connected together has been developed.

[0003] When assembling a battery, a process of injecting an electrolyte into an outer container may be performed. The electrolyte is injected into the outer container, for example, through a filling port provided in the lid, from the front side of the lid toward the back side of the lid. During this process, the electrolyte adheres to the vicinity of the filling port on both the front and back sides of the lid. After the electrolyte is injected, a cleaning process around the filling port may be performed. However, while the front side of the lid is easy to clean, the back side of the lid is difficult to clean. Therefore, even after the cleaning process, some areas near the filling port on the back side of the lid remain unwiped.

[0004] If any part of the electrolyte is not wiped off, when the pressure inside the outer container is reduced in the subsequent sealing process of the inlet, the electrolyte remaining near the inlet inside the outer container may spray out and re-adhere to the surface of the lid. The re-adhesion of the electrolyte to the surface of the lid can hinder the sealing of the inlet, resulting in product defects. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-029208 [Patent Document 2] Japanese Patent Application Publication No. 2014-035870 Summary of the Invention [Problem to be solved by the invention]

[0006] The problem to be solved by the present invention is to provide a lid assembly that can improve yield by increasing reliability when sealing a liquid filling hole, and a battery that has this lid assembly. [Means for solving the problem]

[0007] According to an embodiment, a lid assembly is provided. The lid assembly includes a plate-shaped lid and a pair of terminals. The lid is attached to an opening of an outer container that houses an electrode group and has a front surface and a back surface. The pair of terminals are spaced apart from each other and disposed on the lid. The lid includes a liquid injection port between the pair of terminals that passes through from the front surface of the lid to the back surface of the lid. A recess or a protrusion is provided on the back surface of the lid in at least a portion between the pair of terminals. The back surface of the lid has an uneven region made up of recesses or protrusions. The uneven region is provided in a ring shape so as to surround the entire periphery of the edge of the pouring hole. The arrangement intervals of the recesses or protrusions are in the range of 1 μm to 500 μm. The average height of the multiple protrusions included in the recesses or protrusions is in the range of 1 μm to 500 μm.

[0008] According to another embodiment, a battery is provided. The battery includes an outer container, an electrode group, and a lid assembly according to an embodiment. The outer container has a bottom wall, side walls extending from the bottom wall, a storage space defined by the bottom wall and the side walls, and an opening formed by the side walls. The electrode group is housed in the storage space of the outer container. The lid assembly is fixed to the opening of the outer container with the back surface of the lid facing the storage space. [Brief explanation of the drawings]

[0009] [Figure 1A] FIG. 2 is a schematic perspective view showing the rear side of the lid assembly according to the first embodiment. [Figure 1B] 1B is a schematic exploded perspective view of the lid assembly shown in FIG. 1A. [Figure 2A] 1B is a schematic perspective view showing the front side of the lid assembly, opposite the lid assembly shown in FIG. 1A. [Figure 2B] 2B is a schematic exploded perspective view of the lid assembly shown in FIG. 2A. [Figure 3] FIG. 2 is a plan view schematically showing the rear surface 12b side of the lid 12 shown in FIG. 1B. [Figure 4]FIG. 2 is a plan view schematically showing the vicinity of a liquid inlet 46 of the lid assembly shown in FIG. 1B. [Figure 5] 5 is a cross-sectional view of the lid taken along line VV in FIG. 4. [Figure 6] 10A and 10B are cross-sectional views each showing an example of a step of pouring an electrolyte solution through a pouring port of a lid according to a reference example. [Figure 7] FIG. 10 is a cross-sectional view schematically showing another example of the step of pouring an electrolyte solution through the pouring port of the lid according to the reference example. [Figure 8] FIG. 10 is a cross-sectional view schematically showing another example of the step of pouring an electrolyte solution through the pouring port of the lid according to the reference example. [Figure 9] FIG. 10 is a cross-sectional view schematically showing another example of the step of pouring an electrolyte solution through the pouring port of the lid according to the reference example. [Figure 10] 4 is a cross-sectional view schematically showing an example of a step of pouring an electrolyte solution through a pouring port of the lid having a recess or a protrusion according to the first embodiment. FIG. [Figure 11] 10 is a cross-sectional view schematically showing another example of the step of pouring an electrolyte solution through the pouring port of the lid having the recessed or protruding portion according to the first embodiment. FIG. [Figure 12] FIG. 10 is a cross-sectional view schematically showing another example of a lid included in the lid assembly according to the embodiment. [Figure 13] FIG. 10 is a plan view schematically showing another example of a lid included in the lid assembly according to the embodiment. [Figure 14] FIG. 10 is a plan view schematically showing another example of a lid included in the lid assembly according to the embodiment. [Figure 15] FIG. 10 is a plan view schematically showing an example of a cover having a recess or a protrusion according to a second embodiment. [Figure 16] 16 is a cross-sectional view of the lid taken along line XVI-XVI in FIG. 15. [Figure 17] 10 is a cross-sectional view schematically showing an example of a step of pouring an electrolyte solution through a pouring port of a lid having a recess or a protrusion according to a second embodiment. FIG. [Figure 18] 10 is a cross-sectional view schematically showing another example of the step of pouring an electrolyte solution through a pouring port of the lid having a recess or a protrusion according to the second embodiment. FIG. [Figure 19] 10 is a cross-sectional view schematically showing another example of the step of pouring an electrolyte solution through a pouring port of the lid having a recess or a protrusion according to the second embodiment. FIG. [Figure 20] 10 is a cross-sectional view schematically showing another example of the step of pouring an electrolyte solution through a pouring port of the lid having a recess or a protrusion according to the second embodiment. FIG. [Figure 21] FIG. 10 is a plan view schematically showing another example of the cover having a recess or a protrusion according to the second embodiment. [Figure 22] 22 is a cross-sectional view of the lid taken along line XXII-XXII in FIG. 21. [Figure 23] FIG. 10 is a plan view schematically showing another example of the cover having a recess or a protrusion according to the second embodiment. [Figure 24] FIG. 24 is a perspective view schematically showing the lid shown in FIG. 23. [Figure 25] FIG. 10 is a perspective view schematically showing a battery according to a second embodiment. [Figure 26] FIG. 26 is an exploded perspective view schematically showing the battery shown in FIG. 25. [Figure 27A] FIG. 27 is a schematic perspective view showing a state in which a part of the electrode group shown in FIG. 26 is developed. [Figure 27B] FIG. 27 is a schematic perspective view showing the electrode group shown in FIG. 26. [Figure 28] 26 is a schematic cross-sectional view taken along the plane XXVIII-XXVIII in FIG. 25. DETAILED DESCRIPTION OF THE INVENTION

[0010] The following describes embodiments with reference to the drawings. Common components throughout the embodiments are designated by the same reference numerals, and redundant explanations will be omitted. Each figure is a schematic diagram for explaining and facilitating understanding of the embodiments. While the shapes, dimensions, and ratios may differ from those of actual devices, these may be appropriately modified in design, taking into consideration the following explanation and known techniques.

[0011] First, a lid assembly 10 that can be distributed when manufacturing a battery 310 will be described in a first embodiment. Next, a battery 310 having the lid assembly 10 will be described in a second embodiment.

[0012] (First embodiment) The lid assembly 10 according to this embodiment is attached to the opening of an outer can (outer container) of a primary or secondary battery, and is used as a lid member that closes the opening of the outer can in an airtight and liquid-tight manner.

[0013] 1A and 1B show the back side of the lid assembly 10, and FIGS. 2A and 2B show the front side of the lid assembly 10.

[0014] The lid assembly 10 includes a lid 12 and a pair of terminals 14a, 14b. The lid assembly 10 may further include a pair of leads 16a, 16b, an insulator 18 having electrical insulation properties, and a valve body (safety valve) 20 provided on the lid 12. Gaskets 22a, 22b having electrical insulation properties are disposed between the lid 12 and the pair of terminals 14a, 14b, respectively.

[0015] For this reason, in this embodiment, the lid assembly 10 has gaskets 22a and 22b, but the gaskets 22a and 22b may be attached to the terminals 14a and 14b in advance. Note that, for example, if an electrically insulating resin material is applied to predetermined positions of the terminals 14a and 14b, the gaskets 22a and 22b may not be necessary.

[0016] When the positive electrode terminal 14a and the negative electrode terminal 14b are disposed on the lid 12, insulating gaskets 22a and 22b may be used, or a hermetic seal using glass may be used.

[0017] The lid assembly 10 according to this embodiment is defined in an XYZ Cartesian coordinate system as shown in FIGS. 1A to 2B.

[0018] As shown in FIGS. 1B and 2B, in this embodiment, the lid 12 is a substantially rectangular plate having a front surface 12a and a back surface 12b. The front surface 12a is formed as the surface of the lid assembly 10. The lid 12 is a flat or substantially flat plate parallel to the XY plane and has an appropriate thickness in the Z-axis direction. The lid 12 is made of a metal such as aluminum, an aluminum alloy, iron, or stainless steel. The thickness of the lid 12 varies depending on the material, but is preferably 0.3 mm or more and 2 mm or less.

[0019] The pair of terminals 14a, 14b are formed of a conductive material. The material of the terminals 14a, 14b varies depending on the type of electrolyte of the battery, etc. When the lid assembly 10 is used as part of a lithium-ion secondary battery, aluminum or an aluminum alloy may be used for the positive terminal 14a. Metals such as copper, nickel, or nickel-plated iron may be used for the negative terminal 14b. Aluminum or an aluminum alloy may also be used for the negative terminal 14b.

[0020] A pair of terminals 14a, 14b are disposed on the lid 12 at a distance from each other. The terminals 14a, 14b can be disposed on the surface side of the lid 12. One of the terminals 14a, 14b is used as the positive terminal 14a, and the other is used as the negative terminal 14b. The positive terminal 14a and the negative terminal 14b are formed in a pin shape having heads 32a, 32b and columnar portions 34a, 34b, respectively. In the example shown in FIGS. 1B and 2B, the heads 32a, 32b are rectangular parallelepiped-shaped, but various shapes, such as a cylindrical shape, are acceptable. In the example shown in FIGS. 1B and 2B, the columnar portions 34a, 34b are cylindrical, but various shapes, such as a rectangular column shape, are acceptable.

[0021] The insulator 18 may be made of a resin material selected from the group consisting of polyester (PET), polyimide, polyphenylene sulfide (PPS), and polypropylene. As shown in Figures 1B and 2B, the insulator 18 has a substantially rectangular shape in this embodiment.

[0022] As shown in FIG. 2B, a pair of recesses 42a, 42b are formed on the surface 12a of the lid 12. The recesses 42a, 42b are generally rectangular. One recess 42a has a through-hole 44a formed therein, and the other recess 42b has a through-hole 44b formed therein. The recesses 42a, 42b may have the same shape as each other or different shapes. A ring-shaped insulating gasket 22a with an opening in the center and having electrical insulation properties is disposed in the recess 42a. A ring-shaped insulating gasket 22b with an opening in the center and having electrical insulation properties is disposed in the recess 42b.

[0023] The head 32a of the positive terminal 14a is disposed relative to the recess 42a of the lid 12 via an insulating gasket 22a having electrical insulation. The head 32b of the negative terminal 14b is disposed relative to the recess 42b of the lid 12 via an insulating gasket 22b having electrical insulation. The heads 32a and 32b of the terminals 14a and 14b protrude from the front surface 12a of the lid 12. The columnar portions 34a and 34b of the terminals 14a and 14b protrude from the back surface 12b of the lid 12. At this time, the positive terminal 14a and the negative terminal 14b are prevented from electrically contacting the lid 12 by the gaskets 22a and 22b, respectively. This prevents the positive terminal 14a and the negative terminal 14b from being electrically connected.

[0024] The lid 12 has a liquid inlet 46 that penetrates from the front surface 12a to the back surface 12b of the lid 12. The liquid inlet 46 allows a fluid such as a liquid to be introduced into or removed from the interior of the outer container. The liquid inlet 46 is configured to allow a fluid to be injected from the front surface 12a toward the back surface 12b when assembling a battery 310 shown in FIG. 25 of a second embodiment, which will be described later. The liquid inlet 46 is also configured to allow a fluid to be discharged from the interior of the outer container from the back surface 12b toward the front surface 12a.

[0025] The liquid inlet 46 can be closed when the battery 310 is assembled. The liquid inlet 46 is closed, for example, by welding, or by placing a sealing lid for closing the liquid inlet 46 on the front surface 12a side of the lid 12 so as to cover the liquid inlet 46, and then welding the sealing lid to the lid 12. Note that the pressure resistance of the liquid inlet 46 after sealing, until communication is established between the back surface 12b and the front surface 12a of the lid 12, is set to be greater than the operating pressure of the valve body 20 (for example, 1.0 MPa).

[0026] 1B and 2B, the insulator 18 has a first surface 18a that is in contact with or close to the back surface 12b of the lid 12, and a second surface 18b that is opposite the first surface 18a and faces the electrode group 314. The second surface 18b cooperates with the leads 16a and 16b to form a part of the back surface of the lid assembly 10.

[0027] Similar to the rear surface 12b of the lid 12, the first surface 18a of the insulator 18 is preferably flat or substantially flat parallel to the XY plane.

[0028] FIG. 3 is a plan view schematically showing the back surface 12b side of the lid 12 shown in FIG. 1B and other figures. As described above, the lid 12 may be a plate having a substantially rectangular shape. The lid 12 has a pair of long side edges 13a, 13b and a pair of short side edges 13c, 13d extending perpendicular or substantially perpendicular to the long side edges. A first region 111 is defined between the through holes 44a and 44b within the plane of the back surface 12b of the lid 12. Meanwhile, a second region 112 is defined on the back surface 12b of the lid 12 outside the first region 111. Here, the back surface 12b has two second regions 112.

[0029] The first region 111 is defined between an imaginary line segment Lx that passes through the center Ax of the through hole 44a and extends in a direction perpendicular to the pair of long side edges 13a, 13b, and an imaginary line segment Ly that passes through the center Ay of the through hole 44b and extends in a direction perpendicular to the pair of long side edges 13a, 13b. The first region 111 excludes the hollow portions of the through holes 44a, 44b, the hollow portion of the liquid injection port 46, and the portion where the valve body 20 is present. In the present specification and claims, "between the pair of terminals" refers to the first region 111.

[0030] The second region 112 is defined over the entire back surface 12b of the lid 12 excluding the region where the first region 111 is defined. In Fig. 3, one second region 112 is defined as a region surrounded by an imaginary line segment Lx, the pair of long edges 13a, 13b, and one of the pair of short edges 13c, 13d (here, short edge 13c). The other second region 112 is defined as a region surrounded by an imaginary line segment Ly, the pair of long edges 13a, 13b, and the other of the pair of short edges 13c, 13d (here, short edge 13d).

[0031] Two pairs of recesses 48a, 48a, 48b, 48b are formed on the back surface 12b of the lid 12. One of the two pairs of recesses 48a, 48a, 48b, 48b is formed in one of the second regions 112, and the other of the two pairs of recesses 48a, 48a, 48b, 48b is formed in the other of the second regions 112.

[0032] For example, two pairs of protrusions 52a, 52a, 52b, 52b are formed on the first surface 18a of the insulator 18. The protrusions 52a, 52a, 52b, 52b on the first surface 18a of the insulator 18 are fitted into the recesses 48a, 48a, 48b, 48b on the back surface 12b of the lid 12, so that the surface of the insulator 18 can be closely attached to the back surface 12b of the lid 12. Furthermore, misalignment between the lid 12 and the insulator 18 is suppressed.

[0033] 1B and 2B, the number of protrusions 52a, 52a, 52b, 52b is the same as the number of recesses 48a, 48a, 48b, 48b. The number of protrusions may be less than the number of recesses.

[0034] Here, an example in which the short side edge 13c of the lid 12 and the short side 19c of the insulator 18 are close to each other will be described, but the short side edge 13c of the lid 12 and the short side 19d of the insulator 18 may also be close to each other.

[0035] The first surface 18a of the insulator 18 has a pair of through holes 54a, 54b through which the columnar portions 34a, 34b of the terminals 14a, 14b pass, and an opening 56 facing the liquid inlet 46 and the valve body 20. These through holes 54a, 54b and opening 56 penetrate to the second surface 18b.

[0036] 1A and 1B, the storage section 62a has, for example, four walls 72a, 72b, 72c, and 72d, and an upper wall 82a having a through-hole 54a. Wall 72a is located on the long side 19a adjacent to the short side 19c, wall 72b is located on the short side 19c, and wall 72c is located on the long side 19b adjacent to the short side 19c. Wall 72d extends parallel or approximately parallel to the short side 19c and defines the boundary between the upper wall 82a and the opening 56.

[0037] Similarly, the storage section 62b has, for example, four walls 74a, 74b, 74c, and 74d, and an upper wall 84a having a through-hole 54b.

[0038] As shown in FIGS. 1A and 1B, one lead 16a has a base 92a and one leg 92b extending from the base 92a. The base 92a and the leg 92b are formed by pressing or the like from a single plate of the same thickness. The leg 92b is bent relative to the base 92a. The base 92a is formed in a substantially rectangular flat plate shape. The base 92a has an opening 92c in which the columnar portion 34a of the terminal 14a is disposed. The flat base 92a is preferably parallel to the XY plane.

[0039] The leg 92b can come into contact with a fixing member 354a of the electrode group 314 (described later). The leg 92b extends in the Z-axis direction away from the lid 12. The leg 92b does not extend straight from the base 92a in the Z-axis direction, but is bent, for example, in the Y-axis direction, in a region indicated by reference numeral 93. In particular, when the base 92a of the lead 16a is placed in the housing 62a, the leg 92b is bent in the region indicated by reference numeral 93 from the wall 72c toward the wall 72a. This is to ensure springiness that ensures reliable contact with the fixing member 354a of the electrode group 314. The region indicated by reference numeral 93 is preferably located close to the base 92a of the leg 92b. This is to maximize the contact area between the leg 92b and the fixing member 354a (described later). The length of the leg 92b along the Z-axis direction depends on the positional relationship with the fixing member 354a, but it is preferable to make it as short as possible.

[0040] As shown in FIG. 1B , a base 92a of one lead 16a of a pair of conductive leads 16a, 16b is disposed in the housing 62a on the second surface 18b of the insulator 18. The columnar portion 34a of the terminal 14a is disposed in the housing 62a through the through-hole 44a in the lid 12 and the through-hole 54a in the insulator 18. The columnar portion 34a of the terminal 14a is disposed in the opening 92c of the base 92a of the one lead 16a disposed in the housing 62a and crimped. Therefore, the terminal 14a is fixed by sandwiching the lid 12, the insulator 18, and the base 92a of the lead 16a. At this time, the terminal 14a and the lead 16a are electrically connected.

[0041] Similarly, the other lead 16b has a base 94a and one leg 94b extending from the base 94a. The base 94a is formed in a generally rectangular flat plate shape. The base 94a has an opening 94c in which the columnar portion 34b of the terminal 14b is disposed. The flat base 94a is preferably parallel to the XY plane.

[0042] As shown in FIG. 1B , the leg 94b can contact a fixing member 356a of the electrode group 314 (described later). The leg 94b extends in the Z-axis direction away from the lid 12. The leg 94b does not extend straight from the base 94a in the Z-axis direction, but is bent, for example, in the Y-axis direction, in a region indicated by reference numeral 95. In particular, when the base 94a of the lead 16b is placed in the housing 62b, the leg 94b is bent in the region indicated by reference numeral 95 from the wall 74c toward the wall 74a. This is to ensure springiness that ensures reliable contact with the fixing member 356a of the electrode group 314. The region indicated by reference numeral 95 is preferably located close to the base 94a of the leg 94b. This is to maximize the contact area between the leg 94b and the fixing member 356a (described later). The length of the leg portion 94b along the Z-axis direction depends on the positional relationship with the fixing member 356a, but it is preferable to make it as short as possible.

[0043] A base 94a of the other lead 16b of the pair of conductive leads 16a, 16b is disposed in the housing portion 62b on the second surface 18b of the insulator 18. The base 94a of the other lead 16b has an opening 94c in which the columnar portion 34b of the terminal 14b is disposed. The columnar portion 34b of the terminal 14b is fixed to the base 94a by crimping. Therefore, the terminal 14b is fixed by sandwiching the lid 12, the insulator 18, and the base 94a of the lead 16b. At this time, the terminal 14b and the lead 16b are electrically connected.

[0044] Therefore, the pair of terminals 14a, 14b are spaced apart while being electrically insulated from each other and are disposed on the lid 12. In addition, the pair of leads 16a, 16b are spaced apart while being electrically insulated from each other by the gaskets 22a, 22b.

[0045] As shown in FIGS. 1A and 1B, a valve element 20 is integrally formed with the lid 12. The valve element 20 is provided on the lid 12 between the pair of terminals 14a, 14b. The valve element 20 is formed, for example, by press working. The valve element 20 may be adjacent to the opening 56 of the insulator 18. The valve element 20 may open to the side where the heads 32a, 32b of the pair of terminals 14a, 14b are provided (the front surface 12a side of the lid 12) when the pressure on the side where the insulator 18 and the pair of leads 16a, 16b are provided (the back surface 12b side of the lid 12) reaches a predetermined pressure. The predetermined pressure that opens the valve element 20 may be set as appropriate.

[0046] 2A, the valve body 20 has an outer frame 102 and a groove 104 provided inside the outer frame 102. The groove 104 of the valve body 20 is formed in an X shape inside the outer frame 102.

[0047] <Explanation of concave or convex parts> Next, a description will be given of the recessed or protruding portions provided on the rear surface 12b of the lid 12. The recessed or protruding portions include a first aspect and a second aspect described below.

[0048] (First aspect) First, the recessed or protruding portion according to the first embodiment will be described with reference to Fig. 4 and Fig. 5. Fig. 4 is an enlarged plan view showing the vicinity of the liquid pouring hole 46 in the plan view of the back surface 12b of the lid 12 shown in Fig. 1B. Fig. 5 is a cross-sectional view of the lid 12 taken along line VV in Fig. 4.

[0049] A plurality of minute recesses or protrusions 120 are provided on the back surface 12b of the lid 12. The minute recesses or protrusions 120 are provided on the back surface 12b of the lid 12 in at least a portion between a pair of terminals. The minute recesses or protrusions 120 may be provided on the entire back surface 12b of the lid 12. In Figures 4 and 5, the minute recesses or protrusions 120 are provided so as to surround the entire periphery of the edge 46e of the liquid pouring hole 46. The region where the minute recesses or protrusions 120 are provided is referred to as an uneven region 121. In Figure 4, the uneven region 121 is indicated by dotted shading.

[0050] The uneven region 121, where minute recesses or protrusions 120 are formed, can exhibit a lotus leaf effect or lotus effect. In other words, the liquid repellency is enhanced on the surface of the uneven region 121. The presence of a highly liquid repellent portion on the back surface 12b of the lid 12 can improve the reliability of sealing in the process from pouring the electrolyte through the pouring hole 46 to sealing the pouring hole 46. This reduces product defects due to sealing failure, thereby improving yield.

[0051] The improvement in the liquid repellency of at least a part of the back surface 12b, which results in an improvement in the reliability of sealing, will be described in more detail with reference to Figures 6 to 11. Figures 6 to 9 illustrate the step of pouring the electrolyte solution through the pouring port of the lid according to a reference example.

[0052] When assembling the battery 310, which will be described later, the lid 12 of the lid assembly 10 is fixed to the opening 326 of the outer container 312 by welding or the like. Thereafter, the electrolyte is poured from the outside of the outer container 312 into the inside of the outer container 312 through the pouring port 46.

[0053] If the back surface 12b of the lid 12 does not have a recess or protrusion 120, droplets 50 of electrolyte solution will remain on both the front surface 12a and the back surface 12b of the lid 12 near the pouring hole 46 after pouring, as shown in FIG. 6. The droplets 50 of electrolyte solution remaining on the front surface 12a of the lid 12 can be easily wiped off. Therefore, when the droplets 50 of electrolyte solution remaining on the front surface 12a of the lid 12 are wiped off, the droplets 50 of electrolyte solution will likely remain only on the back surface 12b of the lid 12, as shown in FIG. 7, for example.

[0054] Before sealing the liquid filling port 46, the pressure inside the outer container is reduced. At this time, as shown in FIG. 8, droplets 50 of the electrolyte remaining near the liquid filling port 46 on the back surface 12b of the lid 12 diffuse through the liquid filling port 46 from the back surface 12b side of the lid 12 toward the front surface 12a side. Thereafter, as shown in FIG. 9, the diffused electrolyte re-adheses near the liquid filling port 46 on the front surface 12a side of the lid 12. The electrolyte adhering near the liquid filling port 46 in this way may prevent the liquid filling port 46 from being sealed, which may result in a defective product.

[0055] 10 is a cross-sectional view schematically illustrating the state of the lid 12 after the electrolyte solution has been poured into the outer container through the lid 12 included in the lid assembly according to the embodiment. The electrolyte solution is unlikely to remain on the surface of the minute recesses or protrusions 120 formed on at least a portion of the back surface 12b of the lid 12. In addition, even if droplets 50 of the electrolyte solution remain on the surface of the minute recesses or protrusions 120, the droplets 50 can be relatively easily dropped from the back surface 12b of the lid 12.

[0056] FIG. 11 is a cross-sectional view schematically illustrating a tilting process, which is optionally performed after the injection process. In FIG. 11, the lid assembly including the lid 12, or the battery including the lid assembly itself, is tilted around the Y-axis direction as a rotation axis. As shown in FIG. 11, when the lid 12 is tilted, the tilt angle easily exceeds the sliding angle of the electrolyte droplet 50. As a result, the electrolyte droplet 50 adhering to the surface of the minute recesses or protrusions 120 falls.

[0057] Thereafter, the droplets 50 of electrolyte solution adhering to the surface 12a of the lid 12 are wiped off. In this way, it is possible to prepare the lid 12 in a state where there are no or almost no remaining droplets 50 of electrolyte solution after the injection of the electrolyte solution. This improves the reliability of the sealing of the injection hole 46. This reduces product defects due to sealing failure.

[0058] The recessed or protruding portions 120 may be formed by a plurality of protruding portions protruding along the Z-axis direction from the surface of the back surface 12b extending along the XY plane, as shown in Fig. 5. Alternatively, the recessed or protruding portions 120 may be formed by a plurality of recessed portions recessed along the Z-axis direction from the surface of the back surface 12b extending along the XY plane, as shown in Fig. 12.

[0059] The recesses or protrusions 120 may form an uneven region including a plurality of minute protrusions (projections). The shape of the protrusions is not particularly limited, and may be, for example, a cylindrical, conical, prismatic, or pyramidal shape. The average diameter of the recesses or protrusions 120 included in the uneven region is, for example, in the range of 1 μm to 500 μm. The arrangement interval between the plurality of recesses or the plurality of protrusions is, for example, in the range of 1 μm to 500 μm. The average height of the plurality of protrusions included in the recesses or protrusions is, for example, in the range of 1 μm to 500 μm. These parameters can be measured, for example, using the length measurement function of a scanning electron microscope (SEM). When measuring each parameter, the average value measured for 10 or more recesses or protrusions is used.

[0060] In the uneven region 121, the number of convex portions or concave portions included per unit area is, for example, 1 / mm 2 ~25,000 pieces / mm 2 The number of convex or concave portions contained per unit area is within the range of 100 / mm 2 ~25,000 pieces / mm 2 When the number of convex portions or the number of concave portions contained per unit area is within this range, the liquid repellency of the electrolyte tends to be excellent.

[0061] Next, referring again to FIG. 4, the position and area where the concave and convex regions 121 are provided will be described.

[0062] The uneven region 121 may be provided in at least a portion between the pair of terminals on the rear surface 12b of the lid 12. The uneven region 121 is preferably provided in the manner shown in Fig. 4, which will be described below.

[0063] An imaginary circle 60 having a radius 60r that is five times the radius 46r of the pouring hole 46 is defined on the back surface 12b of the lid 12. The edge 46e of the pouring hole 46 and the imaginary circle 60 may be concentric with each other. On the back surface 12b of the lid 12, the area surrounded by the edge 46e of the pouring hole 46 and the imaginary circle 60 is defined as a third area 113. The third area 113 is a region that is included in the first area 111 shown in FIG. 3 . In other words, the third area 113 is a part of the first area 111.

[0064] The uneven region 121 is preferably provided in at least a part of the third region 113. In other words, on the back surface 12b of the lid 12, the recessed or protruding portion 120 is preferably provided at a distance from the center 46c of the liquid inlet 46 that is five times or less the radius 46r of the liquid inlet 46 (the distance along the radial direction of the circle 60). The reason for this is that the closer the uneven region 121 is formed to the liquid inlet 46, the more easily the electrolyte solution adhering to the back surface 12b of the lid 12 can be prevented from diffusing toward the front surface 12a of the lid 12 after the electrolyte is poured. Therefore, the uneven region 121 is preferably provided adjacent to the edge 46e of the liquid inlet 46, as shown in FIG. 4.

[0065] The shape of the edge 46e of the pouring port 46 is preferably circular or approximately circular, but there are no particular limitations on the shape. The shape of the edge 46e of the pouring port 46 may be, for example, elliptical, square, or rectangular. If the shape of the edge 46e of the pouring port 46 is not circular or approximately circular, the imaginary circle 60 is set using half the length of the longitudinal direction of the edge 46e of the pouring port 46 (the length of the longest part on the XY plane) as the reference, instead of using the radius 46r as the reference.

[0066] The uneven region 121 is provided to occupy, for example, 10% to 100% of the area of ​​the third region 113, preferably 30% to 100% of the area, and more preferably 50% to 100% of the area of ​​the third region 113. The greater the proportion of the area occupied by the uneven region 121 in the area of ​​the third region 113, the greater the effect of suppressing diffusion of the electrolyte from the injection port due to pressure reduction inside the outer container before sealing the outer container.

[0067] As shown in Fig. 13, the uneven region 121 does not have to be provided adjacent to the edge 46e of the liquid pouring port 46. Furthermore, although Figs. 4 and 13 show the case where the uneven region 121 is provided in an annular shape so as to surround the entire periphery of the edge 46e of the liquid pouring port 46, the uneven region 121 does not have to be provided in an annular shape around the liquid pouring port 46. When the uneven region 121 is provided in an annular shape so as to surround the entire periphery of the edge 46e of the liquid pouring port 46, it may be provided adjacent to the edge of the liquid pouring port or may be provided spaced apart from the edge of the liquid pouring port.

[0068] The uneven region 121 may be divided into a plurality of portions on the back surface 12b of the lid 12. The uneven region 121 may be divided into portions within the third region 113, as shown in Fig. 14, for example. In this case as well, droplets of the electrolyte are less likely to adhere to the back surface 12b of the lid 12 during the electrolyte injection step, thereby reducing the number of defective products.

[0069] The minute recesses or protrusions 120 can be formed, for example, by subjecting the rear surface 12b of the lid 12 to laser processing or etching.

[0070] (Second aspect) Next, the recessed or protruding portion according to the second embodiment will be described. The lid 12 included in the lid assembly according to the second embodiment may have the same structure as the embodiment described with reference to Figures 4 to 14, etc., except for the details described below. Figure 15 is a plan view showing a schematic enlargement of the vicinity of the liquid pouring hole 46 on the back surface 12b of the lid 12 according to the second embodiment. Figure 16 is a cross-sectional view showing a schematic cross-section of the lid 12 taken along line XVI-XVI in Figure 15.

[0071] The lid 12 included in the lid assembly according to the second embodiment has at least one protrusion 130 protruding from the back surface 12b of the lid 12, instead of the minute recesses or protrusions according to the first embodiment. In Figures 15 and 16, one protrusion 130 is provided adjacent to the edge 46e of the liquid pouring hole 46. Here, the protrusion 130 protrudes from the back surface 12b of the lid 12 in an annular shape so as to surround the entire circumference of the edge 46e of the liquid pouring hole 46, but the protrusion 130 does not have to be provided in an annular shape. When the protrusion 130 is provided in an annular shape so as to surround the entire circumference of the edge 46e of the liquid pouring hole 46, it may be provided adjacent to the edge of the liquid pouring hole or may be provided spaced apart from the edge of the liquid pouring hole.

[0072] Forming at least one protrusion 130 on the rear surface 12b of the lid 12 can improve the reliability of sealing in the process from pouring the electrolyte to sealing the pouring hole 46. This will be described with reference to FIGS. 17 to 20.

[0073] 6 to 11 , when assembling the battery 310 described below, the lid 12 of the lid assembly 10 is fixed to the opening 326 of the outer container 312 by welding or the like. Thereafter, the electrolyte is poured from the outside of the outer container 312 into the inside of the outer container 312 through the pouring port 46.

[0074] After pouring, droplets 50 of the electrolyte remain on the back surface 12b of the lid 12 near the pouring hole 46, as shown in FIG. 17, for example. The outer wall of the protrusion 130 extends in a direction away from the back surface 12b of the lid 12. Therefore, compared to a case where the back surface 12b of the lid 12 does not have the protrusion 130, the droplets 50 of the electrolyte are more likely to fall off.

[0075] In particular, it is preferable that the protrusions 130 have a tapered structure in a direction away from the rear surface 12b of the lid 12. FIGS. 17 to 20 show, as an example, a case where the protrusions 130 have a tapered shape. When the protrusions 130 have a tapered shape, it is possible to obtain the effect of making it easier for the droplets 50 of electrolyte solution adhering to the outer wall of the protrusions 130 to fall off. Some of the remaining droplets 50 of electrolyte solution fall off the outer wall of the protrusions 130, as shown in FIG. 18, for example.

[0076] The droplets 50 of electrolyte remaining on the surface 12a of the lid 12 can be easily wiped off. Therefore, when the droplets 50 of electrolyte remaining on the surface 12a of the lid 12 are wiped off, the droplets 50 of electrolyte tend to remain only on the back surface 12b of the lid 12, as shown in Fig. 19. The droplets 50 of electrolyte may remain, for example, at the base of the protrusion 130, i.e., near the boundary between the back surface 12b of the lid 12 and the protrusion 130.

[0077] Before sealing the liquid filling port 46, the interior of the outer container is depressurized. At this time, as shown in FIG. 20 , an airflow F is generated due to the reduced pressure. If the protrusion 130 were not present, droplets 50 of the electrolyte remaining on the back surface 12b of the lid 12 would tend to spray out of the outer container through the liquid filling port 46. In contrast, if the protrusion 130 is present, droplets 50 of the electrolyte remaining at the base of the protrusion 130 are blocked by the protrusion 130 even if an airflow F is generated, and are therefore less likely to spray out of the outer container.

[0078] Therefore, even after the electrolyte injection step and the decompression step, droplets 50 of the electrolyte are unlikely to remain on the surface 12a of the lid 12. This increases the reliability of the sealing of the injection port 46, thereby reducing product defects due to sealing failure.

[0079] Next, the position where at least one protrusion 130 is provided, the dimensions of the protrusion 130, etc. will be described.

[0080] The position of at least one protrusion 130 on the back surface 12b of the lid 12 is not particularly limited as long as it is between a pair of terminals. While FIGS. 15 and 16 show the case where the protrusion 130 is provided adjacent to the edge 46e of the liquid inlet 46, the protrusion 130 may be provided at a position spaced apart from the edge 46e of the liquid inlet 46, as shown in FIGS. 21 and 22. Even in this case, the effect of suppressing the electrolyte remaining on the back surface 12b of the lid 12 from spraying out toward the front surface 12a of the lid 12 through the liquid inlet 46 during the depressurization step can be obtained. In other words, the reliability of sealing the liquid inlet 46 can be improved.

[0081] The protrusion 130 is preferably provided in at least a portion of the third region 113 described with reference to FIG. 4. In other words, at least one protrusion 130 is preferably provided on the back surface 12b of the lid 12 at a distance from the center 46c of the liquid inlet 46 that is five times or less the radius 46r of the liquid inlet 46. As shown in FIGS. 15 and 21, the third region 113 is a region surrounded by the edge 46e of the liquid inlet 46 and an imaginary circle 60. By providing the protrusion 130 near the liquid inlet 46, such as in the third region 113, droplets 50 of the electrolyte remaining on the back surface 12b of the lid 12 are less likely to be ejected outside the outer container during depressurization. The protrusion 130 is preferably provided at least in a position adjacent to the edge 46e of the liquid inlet 46, even within the third region 113.

[0082] At least one protrusion 130 may be provided on the back surface 12b of the lid 12. FIGS. 23 and 24 schematically illustrate an example in which a plurality of protrusions 130 are present. The ridgeline connecting the apex (i.e., the tapered tip) of the tapered protrusion 130 preferably extends to surround the liquid inlet 46. For example, as shown in FIG. 23 , the ridgeline 131 of the protrusion 130 is preferably perpendicular or substantially perpendicular to the perpendicular line H drawn from the center 46c of the liquid inlet 46 to the ridgeline 131. In this case, when the pressure inside the outer container is reduced and an airflow F is generated, the protrusion 130 is likely to prevent the movement of droplets of electrolyte remaining on the back surface 12b of the lid 12. Although not illustrated, the ridgeline of the protrusion 130 also extends to surround the liquid inlet 46 in FIGS. 15 and 21 described above.

[0083] The shape of the protrusion 130 is not particularly limited as long as it is provided between the pair of terminals (first region) on the back surface 12b of the lid 12. The protrusion 130 may have, for example, a cylindrical shape, a prismatic shape, a conical shape, a pyramidal shape, or a shape that is an appropriate combination of these.

[0084] The height of the protrusion 130 is, for example, in the range of more than 500 μm and not more than 2.0 mm. When a plurality of protrusions 130 is provided, the heights of the protrusions 130 may be the same as or different from one another. The width of the protrusion 130 in the longitudinal direction is, for example, in the range of 0.1 mm to 10 mm. The width of the protrusion 130 in the lateral direction is, for example, in the range of 0.1 mm to 10 mm. The height of the protrusion 130 is the length of the protrusion 130 along the Z-axis direction. The width in the longitudinal direction and the width in the lateral direction are each the length of the protrusion 130 along any of the in-plane directions of the XY plane.

[0085] The protrusion 130 can be formed by, for example, subjecting the rear surface 12b of the lid 12 to laser processing or etching.

[0086] The lid assembly according to this embodiment can prevent the electrolyte injected into the outer container from spraying out of the outer container when the pressure is reduced during the electrolyte injection, depressurization, and sealing steps that may be performed when assembling a battery, thereby improving the reliability of the sealing step and reducing the number of defective products.

[0087] (Second embodiment) Next, a second embodiment will be described with reference to FIGS. In this embodiment, a battery 310 in which the lid assembly 10 described in the first embodiment can be used will be described.

[0088] In this embodiment, the battery 310 includes an outer container 312, an electrode group 314, and a lid assembly 10. The lid assembly 10 includes a lid 12 having either the first or second aspect of the first embodiment. The battery 310 may be a rechargeable nonaqueous electrolyte battery. The battery 310 may be, for example, a lithium-ion secondary battery.

[0089] As in the first embodiment, an XYZ orthogonal coordinate system is used.

[0090] The outer container 312 has a bottom wall 322 and a side wall 324 extending from the bottom wall 322. The outer container 312 has a cylindrical shape with a bottom, and the side wall 324 forms an opening 326. In the outer container 312, the bottom wall 322 and the side wall 324 define a storage space in which the electrode group 314 is stored. The storage space is open to one side (upper side) in the Z direction of the outer container 312. The lid assembly 10 is fixed to the opening 326 so that the back surface 12b of the lid 12 faces the storage space of the outer container.

[0091] The bottom wall 322 is formed in a substantially rectangular shape. The bottom wall 322 is parallel to the XY plane and has a pair of long edges 332a, 332b parallel to the X-axis direction and a pair of short edges 334a, 334b ​​parallel to the Y-axis direction. The side wall 324 has a pair of long side walls 336a, 336b bounded by the pair of long edges 332a, 332b of the bottom wall 322, and a pair of short side walls 338a, 338b bounded by the pair of short edges 334a, 334b ​​of the bottom wall 322. Each of the side walls 336a, 336b, 338a, 338b extends from the bottom wall 322 toward the opening 326 parallel to the Z-axis.

[0092] The opening 326 is parallel to the XY plane, similar to the bottom wall 322. The opening 326 is generally rectangular, having a pair of long sides (long edges) 342a, 342b parallel to the X-axis direction and a pair of short sides (short edges) 344a, 344b parallel to the Y-axis direction. Therefore, the outer container 312 of this embodiment has a rectangular can shape.

[0093] The outer container 312 is formed, for example, from a metal plate. Examples of metal that can be used include aluminum, aluminum alloy, iron, and stainless steel. The lid 12 of the lid assembly 10 is preferably formed from the same material as the outer container 312, but may be formed from a different material.

[0094] The long side walls 336a, 336b of the outer container 312 occupy the largest area of ​​the outer container 312. Therefore, it is preferable to make the thickness of the plates constituting the long side walls 336a, 336b of the outer container 312 as thin as possible to improve the heat dissipation of the battery 310. The thickness of the plates constituting the long side walls 336a, 336b of the outer container 312 is preferably 2.0 mm or less, and more preferably 1.0 mm or less.

[0095] On the other hand, the rigidity decreases as the thickness of the long side walls 336a, 336b of the outer container 312 decreases. For this reason, for example, the thickness of the long side walls 336a, 336b of the outer container 312 is preferably 0.3 mm or more, and more preferably 0.5 mm or more.

[0096] The thickness of the short-side walls 338a, 338b of the outer container 312 is preferably 2.0 mm or less, and more preferably 1.0 mm or less, similar to the thickness of the long-side walls 336a, 336b. The thickness of the bottom wall 322 is preferably 2.0 mm or less, and more preferably 1.0 mm or less, similar to the thickness of the long-side walls 336a, 336b and the short-side walls 338a, 338b.

[0097] The thicknesses of the bottom wall 322, long side walls 336a and 336b, and short side walls 338a and 338b of the outer container 312 are obtained by measuring the thickness of the central portion of each plate with a micrometer. As the micrometer, for example, a Quick Mini PK-1012CPS manufactured by Mitutoyo Corporation or a device having equivalent functions is used.

[0098] As shown in FIGS. 27A and 27B, the electrode group 314 has a positive electrode 362, a negative electrode 364, and a plurality of separators (electrical insulating layers) 366. The positive electrode 362, the negative electrode 364, and the separators 366 are formed, for example, in strip shapes whose length is sufficiently long relative to their width. The separator 366 is disposed between the positive electrode 362 and the negative electrode 364. In this state, the positive electrode 362, the separator 366, and the negative electrode 364 are wound into a roll around the winding axis Ra to form a roll body 352. The roll body 352 is formed into a flat shape after or while being wound.

[0099] In this case, the electrode group 314 has a roll body 352 formed in a flat shape, a positive electrode current collector tab 354, and a negative electrode current collector tab 356. The positive electrode current collector tab 354 and the negative electrode current collector tab 356 are spaced apart along the winding axis. A separator 366 is exposed on the outer peripheral surface of the roll body 352.

[0100] The positive electrode 362 of the roll 352 of the electrode group 314 has a positive electrode current collector 362a and a positive electrode active material-containing layer 362b. The positive electrode current collector tab 354 is a portion of the positive electrode current collector 362a that is not covered with the positive electrode active material-containing layer 362b.

[0101] The positive electrode current collector 362a is, for example, a metal foil such as aluminum, an aluminum alloy, copper, or nickel. Note that the positive electrode current collecting tab 354 does not have to be integrated with the positive electrode current collector 362a. That is, the positive electrode current collecting tab 354 may be formed by joining a metal foil to one long side of the positive electrode current collector 362a. As the metal foil, the same material as that of the positive electrode current collector 362a can be used.

[0102] The positive electrode active material-containing layer 362b may be provided on both main surfaces of the positive electrode current collector 362a, or may be provided on one main surface. The positive electrode active material-containing layer 362b contains a positive electrode active material. The positive electrode active material-containing layer 362b may contain a conductive agent and a binder in addition to the positive electrode active material.

[0103] As the positive electrode active material, for example, a lithium transition metal composite oxide is used. The lithium transition metal composite oxide is, for example, LiCoO2, LiNi 1-x Co x O2 (0 < x < 0.3), LiMn x Ni y Co z O2 (0 < x < 0.5, 0 < y ≤ 0.8, 0 ≤ z < 0.5), LiMn 2―x M x O4 (M is at least one element selected from the group consisting of Mg, Co, Al, and Ni, 0 < x < 0.2), LiMPO4 (M is at least one element selected from the group consisting of Fe, Co, Ni, and Mn), etc.

[0104] The average particle diameter of the secondary particles of the positive electrode active material is preferably 10 μm or less, and more preferably 6 μm or less. When the average particle diameter of the secondary particles of the positive electrode active material is small, the internal resistance is small, so the heat generation associated with charge and discharge tends to be small. Therefore, when the average particle diameter of the secondary particles of the positive electrode active material is small, the life performance of the battery 310 can be improved.

[0105] The conductive agent enhances the electron conductivity of the electrode. As the conductive agent, carbonaceous materials such as acetylene black, carbon black, and graphite can be used.

[0106] The binder enhances adhesion between the active material, conductive agent, and current collector. Examples of binders that can be used include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and fluorine-based rubber.

[0107] In the positive electrode active material-containing layer 362b, the compounding ratio of the positive electrode active material, conductive agent, and binder is preferably in the range of 80 to 95 mass % of the positive electrode active material, 3 to 18 mass % of the conductive agent, and 2 to 7 mass % of the binder.

[0108] The density of the positive electrode active material containing layer 362b is 2.79 / cm 3 More than 3.39 / cm 3 It is preferable that the density of the positive electrode active material containing layer 362b is 3.39 / cm or less. It has been found that when the density of the positive electrode active material containing layer 362b is within this range, the life performance of the battery 310 tends to be high. In other words, when the density of the positive electrode active material containing layer 362b is 3.39 / cm 3 When the density of the positive electrode active material containing layer 362b is 2.79 / cm or less, twisting is unlikely to occur in the positive electrode when gas is generated, and the increase in the distance between the electrodes is suppressed, thereby improving the performance of the battery 310. 3 If this is the case or more, the distance between the positive electrode active material particles becomes appropriate, and the internal resistance tends to be low.

[0109] The negative electrode 364 of the roll 352 of the electrode group 314 has a negative electrode current collector 364a and a negative electrode active material-containing layer 364b. The negative electrode current collector tab 356 is a portion of the negative electrode current collector 364a that is not covered with the negative electrode active material-containing layer 364b.

[0110] The negative electrode current collector 364a is, for example, a metal foil made of aluminum, an aluminum alloy, copper, nickel, or the like. The negative electrode current collector tab 356 does not have to be integrated with the negative electrode current collector 364a. That is, the negative electrode current collector tab 356 may be formed by joining a metal foil to one long side of the negative electrode current collector 364a. The metal foil may be the same as that of the negative electrode current collector 364a.

[0111] The negative electrode active material-containing layer 364b may be provided on both main surfaces of the negative electrode current collector 364a or on one of the main surfaces. The negative electrode active material-containing layer 364b contains a negative electrode active material. The negative electrode active material-containing layer 364b may contain a conductive agent and a binder in addition to the negative electrode active material.

[0112] The negative electrode active material has a lower limit of the potential at which lithium ions can be charged and discharged: 1.0 V (vs. Li / Li + ) or more. As such a compound, it is preferable to use lithium titanium composite oxide. Lithium titanium composite oxide undergoes almost no volume change during charge / discharge reactions. Therefore, using lithium titanium composite oxide as the negative electrode active material can suppress electrode expansion and contraction. Therefore, using lithium titanium composite oxide as the negative electrode active material can make it more difficult for the electrode to twist during gas generation. Furthermore, lithium titanium composite oxide dissipates little heat during charge / discharge. Therefore, using lithium titanium composite oxide as the negative electrode active material can improve the life performance of battery 310 even if the areas of long side walls 336a, 336b of outer container 312 are relatively small and have low heat dissipation.

[0113] Examples of lithium titanium composite oxides include Li 4+x Ti5O 12 (0≦x≦3) and Li with ramsdellite structure 2+y Examples of titanium-containing oxides include Ti3O7 (0≦y≦3) and orthorhombic titanium-containing oxides. Examples of titanium-containing oxides of orthorhombic crystal structure include sodium-containing niobium titanium composite oxides. Examples of sodium-containing niobium titanium composite oxides include those represented by the general formula Li 2+v Na 2-w M1 x Ti 6-y-z Nb y M2 z O 14+δA compound represented by (0 ≦ v ≦ 4, 0 < w < 2, 0 ≦ x < 2, 0 < y < 6, 0 ≦ z < 3, y + z < 6, -0.5 ≦ δ ≦ 0.5, M1 contains at least one selected from Cs, K, Sr, Ba, Ca, and M2 contains at least one selected from Zr, Sn, V, Ta, Mo, W, Fe, Co, Mn, Al) is included.

[0114] When using a sodium-containing niobium titanium composite oxide as the negative electrode active material, Li 4+x Ti5O 12 Compared with the case of using it, the negative electrode potential can be lowered, so the voltage of the battery 310 can be increased.

[0115] The average primary particle diameter of the negative electrode active material is preferably 1 μm or less. When the average particle diameter of the primary particles of the negative electrode active material is small, the internal resistance decreases, so the heat generation associated with charge and discharge tends to be small. Therefore, when the average particle diameter of the primary particles of the negative electrode active material is small, the life performance of the battery 310 can be improved.

[0116] The negative electrode active material-containing layer 364b may contain a negative electrode active material other than the lithium titanium composite oxide. Examples of such other negative electrode active materials include carbonaceous materials such as graphite, tin-silicon-based alloy materials, and the like.

[0117] The conductive agent enhances the electron conductivity of the electrode. As the conductive agent, acetylene black, carbon black, graphite, etc. can be used.

[0118] The binder enhances the adhesion of the active material, the conductive agent, and the current collector. Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluorine-based rubber, styrene-butadiene rubber, and the like.

[0119] In the negative electrode active material-containing layer 364b, the mixing ratio of the negative electrode active material, the conductive agent, and the binder is preferably in the range of 73 to 98% by mass of the negative electrode active material, 0 to 20% by mass of the conductive agent, and 2 to 7% by mass of the binder.

[0120] The separator 366 functions as an insulating layer. The separator 366 is, for example, a porous membrane or a nonwoven fabric. The porous membrane and the nonwoven fabric may each contain at least one compound selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, and cellulose. The separator 366 may be an organic fiber membrane or an inorganic membrane that covers at least a portion of the main surfaces of the positive electrode 362 and the negative electrode 364. Alternatively, a solid electrolyte layer may be used as the insulating layer instead of the separator 366.

[0121] The thickness of the separator 366 is preferably 6 μm or more and 15 μm or less. When the thickness of the separator 366 is within this range, the safety, capacity, and lifespan of the battery 310 can be improved. That is, when the thickness of the separator 366 is 6 μm or more, the probability of short-circuiting between the positive electrode 362 and the negative electrode 364 can be reduced, thereby improving the safety and reliability of the battery 310. On the other hand, when the thickness of the separator 366 is 15 μm or less, an increase in the amount of sub-components in the battery 310 can be suppressed, thereby improving the energy density. Furthermore, when the thickness of the separator 366 is 15 μm or less, an appropriate amount of voids is present in the outer container 312, making the battery 310 less likely to expand when gas is generated, thereby improving the battery characteristics.

[0122] An electrolyte (not shown) may be held in the positive electrode 362, the negative electrode 364, and the separator 366. The electrolyte may be a nonaqueous electrolyte containing an electrolyte salt and an organic solvent. That is, the battery 310 according to the embodiment may be a nonaqueous electrolyte battery. The nonaqueous electrolyte may be liquid or gel. A liquid nonaqueous electrolyte is prepared by dissolving the electrolyte in an organic solvent. A gel nonaqueous electrolyte is prepared by gelling a liquid nonaqueous electrolyte using a polymer material. The concentration of the electrolyte salt in the liquid nonaqueous electrolyte is, for example, 0.5 mol / L or more and 2.5 mol / L or less.

[0123] Examples of the electrolyte include lithium salts such as lithium perchlorate (LiCl), lithium hexafluorophosphate (LiPF), lithium tetrafluoroborate (LiBF), lithium hexafluoride (LiAsF), lithium trifluoromethasulfonate (LiCFSO), and lithium bistrifluoromethylsulfonylimide [LiN(CFSO)], as well as mixtures thereof. The electrolyte is preferably one that is resistant to oxidation even at high potentials, and LiPF is most preferred.

[0124] Examples of organic solvents include cyclic carbonates such as propylene carbonate (PC), ethylene carbonate (EC), and vinylene carbonate, chain carbonates such as diethyl carbonate (DEC), dimethyl carbonate (DMC), and methyl ethyl carbonate (MEC), cyclic ethers such as tetrahydrofuran (THF), 2-methyltetrahydrofuran (2MeTHF), and dioxolane (DOX), chain ethers such as dimethoxyethane (DME), and diethane (DEE), γ-butyrolactone (GBL), acetonitrile (AN), and sulfolane (SL). These organic solvents may be used alone or in combination of two or more.

[0125] Examples of polymeric materials include polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), and polyethylene oxide (PEO).

[0126] As the non-aqueous electrolyte, a room temperature molten salt (ionic melt) containing lithium ions may be used.

[0127] As shown in FIG. 28 , a conductive fixing member 354a is fixed to the positive electrode current collector tab 354. The fixing member 354a is preferably fixed at a position closer to an upper surface 352d (described later) of the electrode group 314 than the winding axis Ra. The fixing member 354a has a substantially U-shaped cross section parallel to the XY plane, and clamps a portion of the positive electrode current collector tab 354. Therefore, the fixing member 354a fixes a portion of the positive electrode current collector tab 354. The fixing member 354a has an appropriate length along the Z-axis direction and can be in surface contact with the leg portion 92b of the lead 16a. Although not shown, it is preferable that the negative electrode side also has a similar structure.

[0128] The fixing members 354a and 356a are preferably made of a conductive metal material such as aluminum, an aluminum alloy, copper, or nickel.

[0129] The nominal capacity A of the battery 310 according to this embodiment is, for example, 7 Ah or more. Therefore, the battery 310 according to this embodiment can be suitably used as a high-capacity battery. There is no particular upper limit to the nominal capacity A, but in one example, it is 15 Ah. In other words, the battery capacity of the battery 310 according to this embodiment is suitably between 7 Ah and 15 Ah.

[0130] The nominal capacity of the battery 310 is the discharge capacity obtained by the following method: First, the battery is charged at a constant current of 0.05 C to the maximum operating voltage in a 25°C environment. Next, the battery is further charged at a current of 0.01 C while maintaining the maximum operating voltage. After that, the battery is discharged at a rate of 0.05 C to the end voltage to obtain the discharge capacity.

[0131] The above-mentioned "maximum operating voltage" is the maximum voltage at which the battery 310 can be used without danger or defects, and is a value specific to each battery 310. The maximum operating voltage is, for example, a voltage described as the "charging voltage" or "maximum safety voltage" in the specifications of the battery 310. The "end voltage" is the lowest operating voltage that can be used while preventing over-discharge of both the positive electrode 362 and the negative electrode 364 of the battery 310, i.e., preventing deterioration of the battery 310, and is a value specific to each battery 310.

[0132] 26, an electrically insulating cover 372 is provided on the positive electrode current collecting tab 354 and fixing member 354a of the electrode group 314. An electrically insulating cover 374 is provided on the negative electrode current collecting tab 356 and fixing member 356a of the electrode group 314. Note that if an insulating coating is applied to the inner circumferential surface of the outer container 312, the insulating covers 372, 374 may not be necessary.

[0133] The insulating cover 372 prevents the current collecting tab 354 and the fixing member 354a from contacting the inner walls of the side walls 336a, 336b, 338a of the outer container 312. The insulating cover 374 prevents the current collecting tab 356 and the fixing member 356a from contacting the inner walls of the side walls 336a, 336b, 338b of the outer container 312.

[0134] The insulating cover 372 has a support portion 372a that supports the bottom surface 352c of the roll body 352. The insulating cover 374 has a support portion 374a that supports the bottom surface 352c of the roll body 352.

[0135] The insulating covers 372 and 374 may be made of a resin material selected from the group consisting of polyester (PET), polyimide, polyphenylene sulfide (PPS), and polypropylene.

[0136] The electrode group 314 is inserted through the opening 326 of the outer container 312 with the fixing members 354a, 356a and the insulating covers 372, 374 attached in predetermined positions. At this time, the support portions 372a, 374a of the insulating covers 372, 374 abut against the bottom wall 322.

[0137] The lid 12 of the lid assembly 10 described in the first embodiment is disposed in the opening 326 of the outer container 312. At this time, the cross section of the battery 310 along the XXVIII-XXVIII plane in FIG. 25 is formed as shown in FIG. 28. The outer container 312 and the electrode group 314 are preferably symmetrical with respect to a central axis Cz parallel to the Z axis. The leg portion 92b of the lead 16a of the lid assembly 10 is in surface contact with the fixing member 354a. Although not shown, the leg portion 94b of the lead 16b of the lid assembly 10 is in surface contact with the fixing member 356a.

[0138] 25 and 26, the lid 12 of the lid assembly 10 is fixed to the opening 326 of the outer container 312 by, for example, welding. At this time, it is preferable that the front surface 12a and the back surface 12b of the lid 12 of the lid assembly 10 are parallel to the bottom wall 322 of the outer container 312.

[0139] Thereafter, the electrolyte is poured into the outer container 312 through the pouring hole 46. After the electrolyte is poured, the pouring hole 46 can be sealed by welding. Alternatively, a sealing lid (not shown) can be placed to cover the pouring hole 46, and the sealing lid can be welded to the lid 12, thereby sealing the pouring hole 46.

[0140] The battery 310 according to this embodiment includes the lid assembly 10 according to the first embodiment. Therefore, the battery 310 according to this embodiment can improve the reliability when sealing the filling hole, thereby reducing the number of defective products and increasing the yield.

[0141] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. The inventions described in the original claims of this application are set forth below. [1] A plate-shaped lid having a front surface and a back surface, attached to an opening of an outer container that houses an electrode group; a pair of terminals spaced apart from each other and disposed on the lid; Equipped with the lid has a liquid injection port between the pair of terminals, the liquid injection port penetrating from the front surface to the back surface, A lid assembly, wherein a recess or a protrusion is provided on the back surface of the lid in at least a portion between the pair of terminals. [2] A lid assembly as described in [1], wherein the recess or protrusion on the back surface of the lid is located at a distance from the center of the pouring hole that is less than five times the radius of the pouring hole. [3] The back surface of the lid has an uneven area formed by the recessed or protruding portions, A lid assembly according to [1] or [2], wherein the arrangement interval of the recesses or protrusions is within the range of 1 μm to 500 μm, and the average height of the multiple protrusions included in the recesses or protrusions is within the range of 1 μm to 500 μm. [4] The lid assembly according to [3], wherein the uneven area is adjacent to the edge of the pouring hole. [5] A lid assembly according to [3] or [4], wherein the uneven area is annularly arranged so as to surround the entire periphery of the edge of the pouring hole. [6] The recessed or protruding portion is at least one protruding portion that protrudes from the back surface of the lid and has a tapered shape, The lid assembly according to [1] or [2], wherein the height of the at least one protrusion is in the range of more than 500 μm and not more than 2.0 mm. [7] The lid assembly according to [6], wherein the at least one protrusion is adjacent to the edge of the pouring hole. [8] A lid assembly according to [6] or [7], wherein the at least one protrusion is annularly arranged so as to surround the entire periphery of the edge of the pouring hole. [9] An outer container having a bottom wall, a side wall extending from the bottom wall, a storage space defined by the bottom wall and the side wall, and an opening formed by the side wall; an electrode group accommodated in the accommodation space of the outer container; The lid assembly according to any one of [1] to [8], wherein the back surface of the lid is fixed to the opening of the outer container so as to face the storage space. A battery having [Explanation of symbols]

[0142] 10...lid assembly, 12...lid, 12a...surface, 12b...back, 13a...long edge, 13b...long edge, 13c...short edge, 13d...short edge, 14a...terminal, 14b...terminal, 16a...lead, 16b...lead, 18...insulator, 18a...first surface, 18b...second surface, 20...valve body, 42a...recess, 42b...recess, 44a...through hole, 44b...through hole, 46...filling hole, 46c...center, 46e...edge, 50...electrolyte droplet, 54a...through hole, 54b...through hole, 56...opening, 60...imaginary circle, 62a...receptacle, 62b...receptacle, 92a...base, 92b...leg, 92c...opening, 94a...base, 94b...leg , 94c...opening, 102...outer frame, 104...groove, 111...first region, 112...second region, 113...third region, 120...concave or convex portion, 121...uneven region, 130...convex portion, 131...ridge line, 310...battery, 312...outer container, 314...electrode group, 352...roll body, 354...positive electrode current collecting tab, 354a...fixing member, 356...negative electrode current collecting tab, 356a...fixing member, 362...positive electrode, 362a...positive electrode current collector, 362b...positive electrode active material containing layer, 364...negative electrode, 364a...negative electrode current collector, 364b...negative electrode active material containing layer, 366...separator, 372...insulating cover, 374...insulating cover, F...air flow, H...vertical line.

Claims

1. a plate-shaped lid having a front surface and a back surface and attached to an opening of an outer container that houses the electrode group; a pair of terminals spaced apart from each other and disposed on the lid; Equipped with the lid has a liquid injection port between the pair of terminals, the liquid injection port penetrating from the front surface to the back surface, a recess or a protrusion is provided on at least a portion of the rear surface of the lid between the pair of terminals, the back surface of the lid includes an annular uneven area that is configured by the recessed or protruding portion and that surrounds the entire periphery of the edge of the liquid pouring port, A lid assembly, wherein the arrangement interval of the recessed or protruding portions is within a range of 1 μm to 500 μm, and the average height of the plurality of protruding portions included in the recessed or protruding portions is within a range of 1 μm to 500 μm.

2. The lid assembly according to claim 1 , wherein the recess or protrusion is provided on the rear surface of the lid at a distance from the center of the pouring hole that is equal to or less than five times the radius of the pouring hole.

3. an outer container having a bottom wall, a side wall extending from the bottom wall, a storage space defined by the bottom wall and the side wall, and an opening formed by the side wall; an electrode group accommodated in the accommodation space of the outer container; The lid assembly according to claim 1 or 2, wherein the back surface of the lid is fixed to the opening of the outer container so as to face the storage space. A battery having

Images