KR20180110086A - Power storage device and manufacturing method thereof - Google Patents

Abstract

An electrical storage device capable of reliably achieving electrical connection between a current collector and a lead with a small welding energy and preventing the separator from melting when the current collector and the lead are electrically connected and thus preventing a short circuit between the positive electrode and the negative electrode, . Wherein at least one of the positive electrode and the negative electrode has an uncoated portion in which the active material layer is not formed and the uncoated portion and the lead are bonded to each other, And a lead connected to at least one of the positive electrode and the negative electrode has a concave portion at a position where the connecting portion is formed and has a first width in one direction a rectangle having a first width w5 in one direction and a sixth width w6 in the other direction surrounds a rectangle having a first width w1 and a second width w2 in the other direction, Lt; w1.

Description

Power storage device and manufacturing method thereof

The present invention relates to a power storage device and a method of manufacturing the same.

BACKGROUND ART In recent years, miniaturization of power storage devices has been progressing, and accordingly, miniaturization of each component constituting power storage devices has become necessary. On the other hand, with respect to product performance, it is required to exhibit performance equivalent to that of existing products, and a compact and yet high-performance electric storage device has been required.

An electrical storage device has an electrical storage device element formed by stacking a positive electrode and a negative electrode formed by forming an electrode active material layer on a current collector with a separator interposed therebetween, and each electrode is electrically connected to an external terminal via a lead. In such an electrical storage device, it is possible to achieve electrical connection between each electrode and the lead by welding leads to an uncoated portion in which the electrode active material layer in the collector of each electrode is not formed.

For example, in Patent Document 1, there is disclosed a positive electrode uncoated portion in which the electrode active material layer in the positive electrode current collector is not formed, and a non-coated portion in which the electrode active material layer is not formed in the negative electrode current collector, In which a lead is bonded. According to this structure, since the contact area between the current collector and the lead is wide, the contact resistance between the current collector and the lead is reduced, so that the current collecting efficiency is improved and a high output secondary battery can be obtained.

Patent Document 2 discloses an electrical storage device in which a non-coated portion and a lead in a current collector are resistance-welded through a convex portion formed in the lead. According to such a configuration, since the desired electrical conduction is secured at the time of resistance welding by the welding electrode, the welding current can be stabilized. As a result, sparking occurs around the welding portion and the welding portion, It is possible to suppress welding defects such as discoloration of the current collectors and leads due to heat.

However, in the technologies described in Patent Documents 1 and 2, since the thicknesses of the leads are all the same, when the welding energy at the time of welding is low, the current collector and the lead are not welded securely, There is a problem that the electrical connection can not be reliably achieved. On the other hand, when the welding energy at the time of welding is high, the heat is accumulated by the reflected light of the welding light, and this heat is transferred to the separator through the current collector. As a result, the separator melts (see Fig. 14) .

Thus, Patent Document 3 discloses a sealed battery in which a slit is formed in a lead and a high energy ray is irradiated along the center line in the longitudinal direction of the slit to reduce the welding energy to a low level.

Specifically, as shown in Fig. 13 (1), a portion where the slit 96 is formed on the lead 95 is superimposed on the non-coated portion 94 in the current collector, and laser welding is performed in this state , A joining portion 97 is formed along the periphery of the slit 96 of the lead 95 as shown in Fig. 13 (2). In Fig. 13, numeral 90 is an electrode body, 91 is a separator, 92 is a negative electrode, and 93 is a positive electrode.

In the sealed battery, however, since the joining portion 97 is formed while dissolving the peripheral portion of the slit 96 of the lead 95, the amount of metal constituting the joining portion 97 is small and the weight of the uncoated portion 94 and the lead 95 It is difficult to reliably achieve the electrical connection, and the resistance tends to become high.

Japanese Patent Laid-Open No. 2006-12830 Japanese Patent Application Laid-Open No. 2010-16043 Japanese Patent Application Laid-Open No. 2008-84755

It is therefore an object of the present invention to surely achieve an electrical connection between a current collector and a lead in an electrode body with a small welding energy and to prevent the separator from melting when the current collector and the lead are electrically connected, Which can prevent a short circuit of the negative electrode and a method of manufacturing the same.

The electrical storage device according to the present invention has an electrode body in which a positive electrode and a negative electrode each having an active material layer formed on a current collector are laminated via a separator, and at least one current collector of the positive electrode and the negative electrode is formed And a connecting portion joining the non-printed portion and the lead is formed,

The lead connected to at least one of the positive electrode and the negative electrode has a concave portion at a position where the bonding portion is formed,

When viewed in plan from the thickness direction of the lead,

A rectangle having a first width w1 in one direction and a second width w2 in the other direction perpendicular to the one direction (hereinafter, also referred to as a "circumscribed rectangle with a concave opening rim") is formed in the opening rim of the concave portion, However,

A rectangle having a fifth width (w5) in one direction and a sixth width (w6) in the other direction (hereinafter also referred to as a circumscribed rectangle of the periphery of the junction) is circumscribed at the periphery of the junction,

And the first width (w1) and the fifth width (w5) satisfy a relationship of w5? W1.

In the present specification, the term " lead " refers to a part or a part that directly or indirectly electrically connects each of the external electrodes of the respective electrodes of the electrode and the electrode.

In the electrical storage device of the present invention, it is preferable that the metal constituting the non-coated portion and the metal constituting the lead are mixed in the bonded portion.

It is preferable that the joining portion is formed to extend from the wall surface to the bottom surface of the concave portion of the lead.

It is also preferable that the first width w1 and the fifth width w5 satisfy a relationship of w1 > w5.

In addition, it is preferable that the periphery of the abutment portion is surrounded by a rectangle circumscribing the opening rim of the concave portion when viewed in plan from the thickness direction of the lead.

In addition, when viewed in plan from the thickness direction of the lead, it is preferable that a plurality of the joining portions exist in a rectangle circumscribing the opening rim of the concave portion of the lead.

In the cross section cut along the direction of the thickness of the lead along the direction of the first width w1, the angle formed by the two imaginary straight lines extending along the wall surface of the concave portion is 0 to 2.62 rad .

It is preferable that the depth D (mm) of the concave portion and the angle? (Rad) satisfy a relation of 0.25? (? + 1) / D.

Further, it is preferable that it is constituted as a lithium ion capacitor.

A method of manufacturing an electrical storage device according to the present invention comprises an electrode body in which a positive electrode and a negative electrode each having an active material layer formed on a current collector are laminated via a separator and at least one of the current collectors There is provided a method of manufacturing an electrical storage device having a non-printed portion and a bonded portion for bonding the non-printed portion and the lead,

A step of preparing a lead in which a thin portion is formed by having a concave portion,

And joining the hollow portion of the concave portion to the thin solid portion by welding so as to form the joining portion.

In the method for manufacturing an electric storage device of the present invention, it is preferable that the welding is laser welding.

In the cross-section cut along the thickness direction of the lead along the direction perpendicular to the direction in which the lead extends, the angle? Formed by the two imaginary straight lines extending along the wall surface of the concave portion is 0 to 2.62 rad .

According to the electrical storage device of the present invention, the electrical connection between the current collector and the lead in the electrode body can be reliably achieved with a small welding energy, the separator does not melt when the current collector and the lead are electrically connected, And short-circuiting of the negative electrode can be prevented.

1 is an explanatory perspective view showing a configuration of an example of a battery device according to the present invention.
Fig. 2 is a front view of the power storage device shown in Fig. 1 viewed from the Y-axis direction. Fig.
Fig. 3 is a cross-sectional view showing a cross section of the power storage device shown in Fig. 1 taken along the X-axis direction. Fig.
Fig. 4 is a cross-sectional view showing a section of the electrical storage device taken along the line IV-IV in Fig. 3;
5 is a cross-sectional view showing a cross section of the power storage device taken along line VV in Fig. 3;
6 is a cross-sectional view for explaining a recessed portion of the lead.
7 is an explanatory view showing the shape of the concave portion.
Fig. 8 is an explanatory view showing the bottom surface shape of the concave portion. Fig.
Fig. 9 is an explanatory view showing a cross-sectional shape of the recess.
Fig. 10 is an explanatory cross-sectional view showing an enlarged view of a joint portion formed from a wall surface to a bottom surface of a concave portion. Fig.
11 is an explanatory view showing a planar shape of the joint portion.
Fig. 12 is a cross-sectional view for explaining a state in which leads are stitched on a positive electrode uncoated portion. Fig.
13 is a cross-sectional view for explaining a step of forming a joint portion in a conventional power storage device.
14 is a photograph and a schematic diagram showing a state in which the separator is melted.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of a power storage device of the present invention will be described.

The battery device of the present invention can be configured as, for example, a lithium ion capacitor, a lithium ion secondary battery, or an electric double layer capacitor.

Hereinafter, a case where the electrical storage device of the present invention is implemented as a lithium ion capacitor (hereinafter also referred to as " LIC ") will be described.

1 is an explanatory perspective view showing the configuration of an example of a battery device according to the present invention. Fig. 2 is a front view of the power storage device shown in Fig. 1 viewed from the Y-axis direction. Fig. Fig. 3 is a cross-sectional view showing a cross section of the power storage device shown in Fig. 1 taken along the X-axis direction. Fig. Fig. 4 is a cross-sectional view showing a section of the electrical storage device taken along the line IV-IV in Fig. 3; 5 is a cross-sectional view showing a cross section of the electrical storage device taken along the line V-V in Fig.

This electric storage device 100 has a metal outer sheath 10 and an electrode body 20 and an electrolytic solution are accommodated in the outer sheath 10. In the drawing, three axes orthogonal to each other are shown as X-axis, Y-axis and Z-axis. The external body 10 of the illustrated example is a flat rectangular box-shaped one whose one side (upper surface perpendicular to the Z direction in Fig. 1) is open. However, the shape of the sheath 10 is not particularly limited as long as it can accommodate the electrode body 20 and the electrolytic solution to be described later. The material of the external body 10 is, for example, aluminum, stainless steel, iron, or the like.

In the external body 10, a long rectangular sealing plate 30 is provided to seal the opening of the external body 10 in an airtight manner. The sealing plate 30 is bonded to the outer casing 10 by, for example, welding. The material of the sealing plate 30 may be, for example, aluminum, stainless steel or iron, but is preferably made of the same material as the case 10.

On the surface of the sealing plate 30, a long rectangular resin holder 50 having a circular opening 56 at a central portion thereof is provided. Further, the sealing plate 30 is provided with a safety valve 34 at its central portion. The safety valve 34 opens the valve when the internal pressure of the external body 10 rises to a predetermined value or higher, whereby the gas inside the external body 10 is discharged to the outside. By opening the valve of the safety valve 34, the internal pressure of the enclosure 10 is prevented from rising.

Two rectangular terminal plates 40a and 40b are disposed on the surface of the one end portion of the resin holder 50 and on the surface of the other end portion, respectively, so as to be spaced apart from each other. Of the two terminal boards 40a and 40b, one terminal board 40a is a negative terminal board and the other terminal board 40b is a positive terminal board. The material of the terminal plate 40a is, for example, copper or nickel. The other terminal plate 40b is made of, for example, aluminum and is preferably made of the same material as the sealing plate 30 and the sheath 10.

Bolts 80 protruding from the surface of each of the terminal plates 40a and 40b are fixed to the terminal plates 40a and 40b. In this example, the terminal plates 40a and 40b and the bolts 80 constitute external terminals.

Each of the terminal plates 40a and 40b, the resin holder 50 and the sealing plate 30 is provided with a through hole 42 which penetrates the terminal plate 40a and 40b in the thickness direction thereof. The through hole is provided with an insulating plate 60 have. Further, a gasket (not shown) may be provided in the through hole to enhance the hermeticity.

The electrode member 20 shown in Fig. 5 is formed by laminating a sheet-like positive electrode 13, a negative electrode 12, a lithium electrode (not shown), and a separator 11, However, a laminate type in which laminated sheets are laminated may also be used.

The negative electrode 12 has a negative electrode active material layer formed on the negative electrode collector, and the negative electrode collector has a negative electrode uncoated portion (not shown) on which the negative electrode active material layer is not formed. As the material of the negative electrode current collector, for example, metals such as copper, stainless steel, and nickel can be mentioned.

The positive electrode 13 has a positive electrode active material layer formed on the positive electrode current collector, and the positive electrode current collector has the positive electrode uncoated portion 14 on which the positive electrode active material layer is not formed. As the material of the positive electrode collector, for example, metals such as aluminum, stainless steel and iron can be mentioned.

Hereinafter, the negative electrode current collector and the positive electrode current collector are collectively referred to as an " electrode collector ", and the negative electrode uncoated portion and the positive electrode uncoated portion are collectively referred to as " In the electrode body 20 shown in Fig. 5, the electrode uncoated portion is formed along the long side direction at one end of the electrode current collector in the short side direction.

As the electrode current collector, a multi-resonant battery or a magnetic resonance resonator is suitably used and can be classified and used according to the target power storage device 100. [

The lithium electrode has a structure in which a lithium metal foil is pressed on the lithium electrode current collector. By electrically connecting the lithium electrode current collector to the negative electrode uncoated portion of the negative electrode current collector constituting the negative electrode 12, lithium ions are generated by dissolving in the electrolyte solution. The generated lithium ions are electrochemically doped into the negative electrode active material layer of the negative electrode 12 through an electrolytic solution (including " intercalate "). As a result, the potential of the negative electrode 12 can be lowered. The electrode body 20 becomes a power generation portion of the power storage device 100. [ In addition to electrically connecting the lithium electrode to the negative electrode uncoated portion of the negative electrode 12, the negative electrode active material layer of the negative electrode 12 and the lithium metal are in direct contact with each other and electrically connected to each other to dope the negative electrode active material layer with lithium ions It is possible.

The one terminal plate 40a is electrically connected to the negative electrode uncoated portion of the negative electrode collector constituting the negative electrode 12. [ In the example shown in Fig. 3, the terminal plate 40a is connected to the negative electrode 12 of the electrode unit 20 via the lead 64. In Fig.

The other terminal plate 40b is electrically connected to the positive electrode uncoated portion 14 of the positive electrode 13 of the electrode body 20. [ Concretely, the terminal plate 40b is connected to the positive electrode 13 of the electrode unit 20 via the internal terminal (not shown) and the lead 64. [ The electrical connection of the positive electrode uncoated portion 14 of the terminal plate 40b is achieved by electrically connecting the terminal plate 40b disposed on the upper surface (Z-axis direction) of the sealing plate 30 to the sealing plate 30, And the positive electrode uncoated portion 14 is electrically connected to the positive electrode 30 via the lead 64. [ Therefore, the terminal plate 40b may be electrically connected to the external body 10 and the sealing plate 30. [

6, the lead 64 has a concave portion 65 at a position where the joining portion 68 joining the electrode uncoated portion and the lead 64 is formed. The thickness T of the lead 64 and the depth D of the concave portion 65 satisfy a relation of 0 < D < T.

Examples of the material of the lead 64 include metals such as aluminum, copper, stainless steel, nickel, and iron.

The thickness T of the lead 64 is preferably 0.5 mm to 6 mm, more preferably 1 mm to 4 mm, and particularly preferably 1.5 mm to 3 mm. If the thickness T of the lead 64 is less than 0.5 mm, the sectional area of the lead 64 becomes small, which may cause a high resistance. On the other hand, when the thickness T of the lead 64 exceeds 6 mm, the welding energy required for the electrical connection between the lead 64 and the electrode uncoated portion becomes excessive, so that the separator 11 is melted and the positive electrode 13, There is a risk of short-circuiting the power supply 12.

The length of the lead 64 is preferably 30 to 100 mm, more preferably 35 to 90 mm, and particularly preferably 40 to 80 mm. The length of the lead 64 also includes the length of the bent portion (hereinafter also referred to as &quot; curved portion &quot;) when the lead 64 is curved in, for example, L shape.

The lead 64 of this example has a curved portion, and the curved portion of the lead 64 is electrically connected to the inner terminal. By providing such a curved portion, the connection with the internal terminal is surely achieved, and the connection area between the lead 64 and the internal terminal is increased, so that the connection resistance can be reduced. The length of the valley portion can be appropriately designed in consideration of the size, performance, and the like of the power storage device 100.

The width of the lead 64 is appropriately set in accordance with the width of the non-printed portion, but is preferably 3 to 20 mm, particularly preferably 5 to 15 mm from the viewpoint of connection resistance

The depth D of the concave portion 65 of the lead 64 is preferably 0.5 mm to 5 mm, particularly preferably 1 to 4 mm.

If the depth D of the concave portion 65 is less than 0.5 mm, the welding energy required for the electrical connection between the lead 64 and the electrode uncoated portion becomes excessive, so that heat is transferred from the lead 64 to the electrode current collector, There is a possibility that the positive electrode 13 and the negative electrode 12 are short-circuited. On the other hand, if the depth D of the concave portion 65 exceeds 5 mm, heat due to welding energy accumulates in the concave portion 65 and accumulates heat, and this heat is transferred to the electrode current collector through the lead 64 As a result, there is a fear that the separator 11 is melted and the positive electrode 13 and the negative electrode 12 are short-circuited.

The shape of the concave portion 65 is not particularly limited, and various shapes can be adopted as shown in Figs. 7A to 7J. Examples of the shape of the concave portion 65 include a rectangle, an ellipse, a dot, a waveform, a zigzag, a rhombus, etc. If the concave portion 65 has more than one concave portion 65 on the lead 64 do. A preferable shape is a rectangle (Fig. 7 (a)), a dot (Fig. 7 (e), and Fig. 7 (j)). 7 (e) and 7 (j) are examples having a plurality of concave portions 65, the number of concave portions 65 is not limited to the number of joints to be formed, And it is possible to set it appropriately. The concave portion 65 has a first width in the one direction (the X-axis direction in the figure) in the opening edge of the concave portion 65 as viewed in plan from the thickness direction of the lead 64 (a circumscribed rectangle of a concave opening rim) 69 having a first width w1 in the first direction and a second width w2 in the other direction perpendicular to the first direction (the Z-axis direction in the drawing) are circumscribed. When the number of the recesses 65 is one and the shape of the opening rim of the recess 65 is a rectangle, the opening rim of the recess 65 coincides with the circumscribed rectangle 69 of the rim opening rim. One direction with respect to the first width w1 means a direction perpendicular to the direction in which the leads 64 extend and the other direction with respect to the second width w2 means a direction in which the leads 64 extend.

The shape of the bottom surface 67 of the concave portion 65 is not particularly limited, but is formed so as to converge in the concave portion 65. Specific shapes of the bottom surface 67 of the concave portion 65 include a rectangle, an ellipse, a dot, a waveform, a zigzag, a rhombus, and the like as shown in (k) The bottom surface 67 only needs to have one or more of the above-described shapes in the concave portion 65. 8 (k)), an ellipse (Fig. 8 (l)), and a dot (Fig. 8 (m) and Fig. 8 (q)). The bottom surface 67 of the concave portion 65 has a third surface 67a extending in one direction (X direction in the figure) on the periphery of the bottom surface 67, as viewed in plan from the thickness direction of the lead 64 (Hereinafter also referred to as &quot; circumscribed rectangle of concave bottom surface &quot;) 71 having a width w3 and a fourth width w4 in the other direction may be formed in a circumscribed state. The one direction of the third width w3 and the other direction of the fourth width w4 are the same as one direction of the first width w1 and the other direction of the second width w2. The first width w1 of the circumscribed rectangle 69 of the concave opening rim of the lead 64 and the third width w3 of the circumscribed rectangle 71 of the concave bottom surface satisfy the relation of w3? W1 , And more preferably satisfies the relationship of w3 &lt; w1.

7 shows a specific example of the shape of the opening rim of the recess 65 and the shape of the bottom 67. The shape of the bottom 67 shown in Fig. 8 and the shape of the recess 67 65 may be combined in any combination.

As shown in Figs. 9 (a) and 9 (d), when the concave portion 65 is cut in the thickness direction of the lead 64, the back surface of the portion where the concave portion 65 is located is flat 9 (b) and 9 (c), it may have a protrusion on the back surface of the portion where the recess 65 is located. However, as shown in FIG. 9 (b) , It is preferable that it is flat. This is because the thickness of the portion (thin portion) forming the bottom surface 67 of the concave portion 65 is small, so that the joining portion 68 can be easily alloyed and reliable electrical connection can be achieved. This is because even if the welding energy is small, the joining is easy and the melting of the separator 11 can be suppressed.

9 (a) to (d) on the left side show the state before the joining portion 68 is formed, and (e) to (h) on the right side show a state in which the joining portion 68 is formed.

The concave portion 65 is formed in the cross section cut in the thickness direction of the lead 64 so that the angle? Formed by two imaginary straight lines extending along the wall surface 66 of the concave portion 65 ) Is preferably from 0 to 2.62 rad, more preferably from 0.35 to 1.92 rad. When the angle? Is excessively small, heat due to welding energy accumulates in the concave portion 65 and heat is accumulated when forming the joint portion 68. This heat is transferred to the electrode current collector through the lead 64 As a result, there is a fear that the separator 11 is melted and the positive electrode 13 and the negative electrode 12 are short-circuited. On the other hand, when the angle? Is excessive, welding energy required for electrical connection between the lead 64 and the electrode uncoated portion becomes excessive, so that the separator 11 melts and the positive electrode 13 and the negative electrode 12 are short- There is a concern. In addition, it is difficult to perform press molding which can be produced at low cost, and it is necessary to perform cutting at a high price, which makes mass production difficult.

The inclination of each of the two virtual straight lines may be the same as shown in Figs. 9A to 9C or may be different from each other as shown in Fig. 9D, Do.

It is preferable that the depth D (mm) and the angle? (Rad) of the concave portion 65 satisfy the relation of 0.25? (? + 1) / D. When the value of (? + 1) / D is less than 0.25, the depth D of the concave portion 65 becomes relatively large, so that the welding energy required for electrical connection between the lead 64 and the electrode non- Therefore, there is a fear that the separator 11 melts and the positive electrode 13 and the negative electrode 12 are short-circuited.

The connecting portion 68 for electrically joining the bottom surface 67 of the concave portion 65 of the lead 64 and the electrode uncoated portion is formed from the wall surface 66 of the concave portion 65 to the bottom surface 67 As shown in Fig. In the case where the joining portion 68 is formed from the wall surface 66 to the bottom surface 67 of the concave portion 65 and the upper surface of the joining portion 68 forms a curved surface, A position changing from a plane to a curved surface is defined as a peripheral position of the bottom surface. That is, in FIG. 10, the distances between points where two straight lines extending along the wall surface of the recess change from a straight line to a curved line correspond to the third width w3 and the fifth width w5, and w3 = w5. With such a configuration, the bonding strength between the lead 64 and the electrode uncoated portion becomes large, and the resistance can be reduced. The joining portion 68 may be formed only on the bottom surface 67 of the recess 65 as shown in Fig. In this case, the third width w3 of the circumscribed rectangle 71 on the bottom surface of the recess in the lead 64 and the fifth width w5 of the circumscribed rectangle 72 on the periphery of the joint satisfy the relation of w3? W5 . According to such a configuration, since the required welding energy is reduced, energy can be saved, the amount of heat transferred to the separator 11 can be reduced, and the further melting of the separator 11 can be suppressed .

It is preferable that the bonding portion 68 is composed of a mixture of the metal constituting the lead 64 and the metal constituting the electrode uncoated portion. Specifically, in the bonding portion 68 relating to the positive electrode 13, the positive electrode uncooled portion 14 and the lead 64 of the positive electrode current collector in the positive electrode 13 are welded and alloyed to each other, ). It is preferable that the alloyed component in the joining portion 68 with respect to the positive electrode 13 is alloyed with a metal including aluminum-derived metal, stainless steel-derived metal, iron-derived metal, and nickel-derived metal. On the other hand, in the joining portion 68 relating to the negative electrode 12, the joining portion 68 is formed by joining the uncoated portion of the negative electrode collector of the negative electrode 12 and the lead 64 by welding. It is preferable that the alloyed component in the joining portion 68 with respect to the negative electrode 12 is alloyed with a metal containing copper, a metal derived from nickel, a metal derived from stainless steel and a metal derived from iron.

As described above, since the joining portion 68 is formed by alloying, reliable electrical connection can be achieved, and dislocations between different types of metals are not generated, and corrosion is less likely to occur, .

The planar shape of the joint portion 68 is not particularly limited but is formed so as to converge in the concave portion 65 and is formed so as to be in the same plane as the periphery of the joint portion 68 when viewed in plan from the thickness direction And is surrounded by the circumscribed rectangle 69 of the concave opening rim. As shown in (r) to (x) in FIG. 11, the planar shape of the specific joint portion 68 includes, for example, a rectangle, an ellipse, a dot, a waveform, a zigzag, and a rhombus. It is sufficient that at least one joining portion 68 is formed in the concave portion 65. 11 (r)), an ellipse (Fig. 11 (s)), a dot (Fig. 11 (t), and Fig. 11 (x)). The example shown in Figs. 11 (t) and 11 (x) is an example having a plurality of joining portions 68, but the number of the joining portions 68 is not limited to the size and number of the concave portions 65, And the like. The joining portion 68 has a fifth width w5 in one direction (X-axis direction in the drawing) on the periphery of the joining portion 68 when viewed from the plane of the lead 64 in the thickness direction (Y- And a sixth width w6 in the other direction (the Z-axis direction in the drawing) are circumscribed. When the number of the joining portions 68 is one and the shape is rectangular, the outline of the joining portion 68 coincides with the circumscribed rectangle of the periphery of the joining portion. The one direction of the fifth width w5 and the other direction of the sixth width w6 are the same as one direction of the first width w1 and the other direction of the second width w2 .

The shape of the joint portion 68 shown in Fig. 11 may be combined with the shape of the bottom surface 67 of the concave portion 65 shown in Figs. 7 and 8. For example, the shape of the concave portion 65 and the bottom surface 67 shown in Fig. 7 (a) and the shape of the joint portion 68 shown in Fig. 11 (t) or 11 (x) The shape of the concave portion 65 and the bottom surface 67 shown in FIG. 7C and the shape of the joint portion 68 shown in FIG. 11 (w) may be combined.

The thickness d of the bonding portion 68 in this specification is the distance from the bottom surface 67 of the recess 65 in the lead 64 to the interface between the lead 64 and the electrode non-conductive portion. The metal constituting the lead 64 and the metal constituting the electrode uncoated portion are mixed and integrated in the joining portion 68. A portion other than the joining portion 68 in the lead 64 and the electrode non- The thickness d of the bonding portion 68 is greater than the thickness d of the interface between the surface of the bonding portion 68 (the bottom surface 67 of the concave portion 65) and the electrode non- .

The thickness d of the bonding portion 68 is, for example, 0.2 to 1 mm.

The first width w1 of the circumscribed rectangle 69 of the opening edge of the recess in the lead 64 and the fifth width w5 of the circumscribed rectangle 72 of the periphery of the joining portion of the power storage device 100 according to the present invention, Satisfies the relationship of w5? W1, and preferably satisfies w5 < w1. That is, by satisfying the condition that the value of w1 / w5 is not less than 1, preferably more than 1, it is possible to form the welding portion 68 with appropriate welding energy without requiring too much welding energy, Can be prevented from melting, and electrical connection between the electrode uncoated portion and the lead 64 can be reliably achieved.

The electrical storage device 100 of the present invention can be manufactured, for example, through the following steps (1) to (8).

(1) A lead 64 having a thin-wall portion is prepared by having a recessed portion 65. The thickness of the thin-wall portion is preferably 0.2 to 2.5 mm.

(2) A gasket is mounted so as to cover the inside of the through hole 42 leading to the terminal formed on the sealing plate 30, the internal terminal is mounted to the through hole 42, and the resin holder 50 is sealed Is formed on the surface of the plate (30).

(3) The terminal boards 40a and 40b and the bolts 80 are electrically connected.

(4) The terminal plates 40a and 40b and one end of the internal terminal are welded.

(5) The other end of the inner terminal is welded to one end of the lead (64).

(6) As shown in Fig. 12, the thinned portion by the recessed portion 65 in the lead 64 is superimposed on the positive electrode uncoated portion 14 of the positive electrode 13 in the electrode body 20, The joint portion 68 is formed by welding the positive electrode uncoated portion 14 of the electrode body 20 to the thin portion by the portion 65 by welding. The welding of the lead 64 and the positive electrode uncoated portion 14 is preferably laser welding. Since laser welding can be performed in a noncontact manner, maintenance of the apparatus is easy. As a result, since there is little deterioration of the apparatus, the maintenance cost is reduced, and the manufacturing cost is reduced.

The negative electrode uncoated portion of the negative electrode 12 and the lead 64 in the electrode member 20 are bonded in the same manner as described above.

(7) The electrode body 20 is received in the external body 10, and the external body 10 and the sealing plate 30 are welded.

(8) The electrolytic solution is injected from the safety valve 34, and the safety valve 34 is welded to the sealing plate 30 to assemble the power storage device 100.

The electrical storage device 100 can be manufactured as described above.

According to this manufacturing method, it is possible to easily form the joint portion 68 even if there is no heat accumulation and the welding energy is small. As a result, it is possible to suppress the melting of the separator 11 by the thermal energy.

The power storage device 100 according to the present invention has the recess 65 at the position where the joining portion 68 is formed in the lead 64 and the first width w1 in the circumscribed rectangle 69 of the opening rim of the recess, And the fifth width w5 in the circumscribed rectangle 72 at the periphery of the joint satisfy the relationship of w5? W1. This makes it possible to suppress heat accumulation in the concave portion 65 due to the bonding energy when bonding the lead 64 and the electrode uncoated portion to each other and to suppress the heat accumulation of the metal constituting the bottom surface 67 of the concave portion 65, It is possible to reliably form the necessary bonding portion 68 for welding the metal constituting the non-coated portion. Further, since the bonding energy is small, melting of the separator 11 due to heat transfer can be suppressed.

Therefore, according to the electrical storage device 100 of the present invention, it is possible to reliably achieve the electrical connection between the electrode current collector and the lead 64 in the electrode assembly 20 with a small welding energy, The separator 11 is not melted and shorting between the positive electrode 13 and the negative electrode 12 can be prevented.

The present invention is not limited to the above-described embodiment, and various modifications are possible. The present invention includes substantially the same configuration as the configuration described in the above embodiment (for example, a configuration having the same function, method, and result, or a configuration having the same purpose and effect). The present invention also includes a configuration in which the configuration described in the above embodiments is replaced with a configuration that is not essential. The present invention also includes configurations that exhibit the same operational effects as those described in the above embodiments, or configurations that can achieve the same purpose. The present invention also includes a configuration in which known technologies are added to the configurations described in the above embodiments.

In the above embodiment, both the positive electrode and the negative electrode have an uncoated portion, but either the positive electrode or the negative electrode may have a non-coated portion.

In the case where both the positive electrode and the negative electrode have an uncoated portion, the lead connected to either the positive electrode or the negative electrode may have a concave portion at a position where the joined portion is formed.

The electrical storage device of the present invention is not limited to the above-described embodiment, and various modifications are possible. For example, although the above embodiment is an example configured as a lithium ion capacitor, the electrical storage device of the present invention may be constituted by a lithium ion secondary battery or an electric double layer capacitor.

Example

Hereinafter, specific examples of the present invention will be described, but the present invention is not limited to these examples.

(Example 1 (S1))

(1) Production of negative electrode:

A graphite powder and a polyvinylidene fluoride powder were prepared. The negative electrode slurry was applied to both surfaces of a negative electrode current collector including copper copper foil by a die coater and dried. At this time, the negative electrode active material layer was formed on both sides of the negative electrode current collector so that the negative electrode uncoated portion was formed along the long side direction at the end portion in the short side direction of the current collector.

(2) Preparation of positive electrode:

Activated carbon powder, acetylene black, a fluorine acrylic binder, and carboxymethyl cellulose were added to water and dispersed to prepare a positive electrode slurry. The positive electrode slurry was coated on both sides of a positive electrode collector including an aluminum porous foil by a die coater and dried. At this time, the positive electrode active material layer was formed so that the positive electrode uncoated portions were formed on both sides of the positive electrode current collector along the long side direction at the end portion in the short side direction of the current collector.

(3) Fabrication of wound electrode body:

A first separator and a second separator each comprising a cellulose / rayon mixed nonwoven fabric were prepared.

Then, a positive electrode was disposed between the two lithium electrodes on the surface of the first separator. At this time, the positive electrode uncoated portion was disposed so as to protrude from one side edge extending along the long side direction of the first separator. Then, on the positive electrode, a second separator was laminated so as to protrude from the side of one edge extending along the long side direction of the second separator by the positive electrode uncoated portion. That is, the second separator was disposed at substantially the same position as the first separator. Subsequently, the negative electrode was laminated on the second separator such that the negative electrode uncoated portion protruded from the other edge side extending along the long side direction of the second separator. Thus, an electrode laminate was formed. Here, the positive electrode and the negative electrode were disposed such that the positive electrode active material layer and the negative electrode active material layer were opposed to each other with the second separator interposed therebetween. This electrode laminate was wound around one end of the electrode stacked body so that the negative electrode was located on the inner side with respect to the central rod made of stainless steel. Next, a lithium electrode current collector made of a copper multi-perovskite is pressed on the surface of the first separator in a state of being spaced from the end of winding of the positive electrode to form a lithium electrode, To prepare a wound-up electrode body. Subsequently, the outer peripheral surface including the winding end portion of the electrode body was covered with a polypropylene film and fixed with a tape. The center rod made of stainless steel was taken out after forming the electrode body, and the electrode body was pressed to form a flat wound electrode body. At this time, the lithium electrode was adjusted so as to be located on the flat portion of the flat wound electrode body.

The negative electrode lead portion, which was nickel-plated on the surface of the copper base body, was superimposed on the negative electrode uncoated portion of the obtained electrode body and was joined by laser welding to electrically connect the negative electrode uncoated portion and the negative electrode lead. Further, the negative electrode lead was electrically connected to the negative electrode terminal plate made of nickel-plated copper by laser welding. Subsequently, the thick portions formed by the concave portions in the L-shaped positive electrode lead made of aluminum are overlapped on the positive electrode uncoated portion of the electrode body and the two thinned portions are formed by laser welding at two portions to form the two joined portions, And the positive electrode lead was electrically connected. Further, the positive electrode lead was electrically connected to the positive electrode terminal plate made of aluminum by laser welding.

In the above, the negative electrode terminal plate and the positive electrode terminal plate are integrated with an aluminum sealing plate through a resin holder made of polypropylene by insert resin molding. The dimensions of the sealing plate are 15 mm (length) x 150 mm (width) x 1.5 mm (thickness).

The positive electrode lead has a shape of L shape, and the length of the long side of the L character is 50 mm, the length of the short side is 20 mm, the length is 70 mm, the width is 10 mm, and the thickness is 3 mm. In the positive electrode lead before laser welding, the outline of the recess is rectangular in shape of 3 mm x 24 mm, and a thin portion with a thickness of 1 mm is formed at the bottom. The angle formed by the two imaginary straight lines extending on the side surface of the concave portion in the section cut along the thickness direction of the positive electrode lead along the width direction of the positive electrode lead is 0.7 rad.

On the other hand, even after laser welding, the positive electrode lead has a rectangular concave portion near the center of the long side. The circumscribed rectangle of the concave opening rim coincides with the outline of the concave portion when viewed from the thickness direction of the positive electrode lead. The first width w1 is 3 mm, the second width w2 is 24 mm, (D) is 2 mm, and the angle of the wall portion is 0.7 rad.

Each of the obtained bonding portions has a rectangular shape and is formed from the bottom surface of the concave portion of the positive electrode lead to the wall portion and is constituted by integrating aluminum constituting the positive electrode lead and aluminum constituting the positive electrode uncoated portion. The surface dimensions of these joints are 1 mm x 11 mm, and the spacing distance between the two joints is 1 mm. A rectangle having a fifth width w5 of 1 mm and a sixth width w6 of 23 mm is externalized at the periphery of the two joints as viewed in plan from the thickness direction of the positive electrode lead, And is surrounded by a circumscribed rectangle of the opening edge of the concave portion.

The value of w1 / w5 was 3.0, and the value of (? + 1) / D was 0.85.

Further, when the first separator and the second separator in the electrode assembly were visually inspected, it was confirmed that they were not melted.

(4) Preparation of lithium ion capacitor:

An electrode body was disposed in an aluminum-made outer body of 15 mm (width) x 150 mm (length) x 100 mm (height). The opening of the rectangular outer container was sealed with a sealing plate and fixed by laser welding. Subsequently, from the hole formed in the sealing plate, an electrolytic solution in which LiPF ₆ was dissolved in propylene carbonate at a concentration of 1 mol / L was injected. Thereafter, an aluminum-made safety valve was welded to the hole formed in the sealing plate. Thus, a wound square-shaped lithium ion capacitor S1 was produced.

&Lt; Example 2 (S2) to Example 7 (S7), Comparative Examples 1 (C1) to 4 (C4)

Lithium ion capacitors (S2 to S7) and lithium ion capacitors (C1 to C4) were produced in the same manner as in Example 1, except that the dimensions of the positive electrode leads and the connection portions were changed according to Table 1 below.

As a result of visually checking the first separator and the second separator in the electrode assembly, it was confirmed that the lithium ion capacitors S2 to S7 were not melted, but it was confirmed that the lithium ion capacitors (C1 to C4) were melted .

&Lt; Comparative Example 5 (C5) >

A winding square type lithium ion capacitor (C5) was produced in the same manner as in Example 1 except that resistance welding was used instead of laser welding in the bonding of the negative electrode uncoated portion and the negative electrode lead and the bonding of the positive electrode uncoated portion and the positive electrode lead .

As described above, resistance welding of the positive electrode uncoated portion and the positive electrode lead was carried out by fitting the positive electrode uncoated portion and the positive electrode lead with a welding electrode having a diameter of 3.5 mm. Further, the obtained joint portion had a circular shape with a surface of 3.3 mm in diameter, and a concave portion was not present around the joint portion.

Further, when the first separator and the second separator in the electrode assembly were visually inspected, it was confirmed that they were not melted. However, it has been confirmed that a plurality of sputtering of metal powder is attached to the first separator and the second separator in the vicinity of the portion where the resistance welding is performed.

[Short circuit test]

The lithium ion capacitor according to Example 1 (S1) to Example 7 (S7) and Comparative Example 1 (C1) to Comparative Example 5 (C5) had a voltage of 3.8 V at a constant current of 10 A under an environment of 25 캜 Then, a constant current-constant voltage charge of applying a constant voltage of 3.8 V was performed for 0.5 hour, and then the cell was discharged at a constant current of 10 A until the cell voltage became 2.2 V. Then, Subsequently, charging and discharging operations of 3.8 V-2.2 V were repeated, and after discharging for 100,000 times, the lithium ion capacitor was taken out of the rectangular external container to check whether the electrode body was short-circuited. The results are shown in Table 1 below.

As for the lithium ion capacitors (S1 to S7), the electrode bodies after 100,000 charge / discharge cycles were confirmed, but there was no short circuit.

Since the value of w1 / w5 is less than 1 in the lithium ion capacitors (C1 to C4) (that is, w1 <w5), thermal energy is trapped outside of the concave portion at the time of laser welding and the leads must be melted in the entire thickness direction Therefore, excessive heat energy was required. As a result, heat is transferred to the first separator and the second separator through the lead and the positive current collector, and the first separator and the second separator are melted. As a result, the lithium ion capacitors (C1 to C4) were short-circuited in the electrode body after 100,000 charge / discharge cycles.

In the lithium ion capacitor C5, since a plurality of metal powder spatters were attached to the electrode body after welding, a short circuit was confirmed in the electrode body after the 100,000 charge / discharge cycle.

10: external body
11: Separator
12: negative pole
13: positive
14: Positive electrode non-
20: Electrode body
30: sealing plate
34: Safety valve
40a, 40b:
42: Through hole
50: Resin holder
56: aperture
60: insulating plate
64: Lead
65:
66: Wall
67: The bottom
68:
69: circumscribed rectangle of concave opening rim
71: circumscribed rectangle at the bottom of the concave portion
72: circumscribed rectangle at the periphery of the joint
80: Bolt
90: Electrode body
91: Separator
92: Negative electrode
93: Positive
94:
95: Lead
96: Slit
97:
100: Power storage device
D: Depth of recess
d: thickness of joint
W1: First width
W2: second width
W3: third width
W4: fourth width
W5: fifth width
W6: Sixth Width

Claims (12)

Wherein at least one of the positive electrode and the negative electrode has an uncoated portion in which the active material layer is not formed, wherein the positive electrode and the negative electrode each having an active material layer on the current collector are stacked with a separator interposed therebetween, And a junction portion joining the lead portion and the lead portion,
The lead connected to at least one of the positive electrode and the negative electrode has a concave portion at a position where the bonding portion is formed,
When viewed in plan from the thickness direction of the lead,
Wherein a rectangle having a first width (w1) in one direction and a second width (w2) in the other direction perpendicular to the one direction is external to the opening rim of the recess,
Wherein a rectangle having a fifth width (w5) in one direction and a sixth width (w6) in the other direction is external to the periphery of the junction,
Wherein the first width (w1) and the fifth width (w5) satisfy a relationship of w5? W1. The electrical storage device according to claim 1, wherein a metal constituting the non-coated portion and a metal constituting the lead are mixed in the bonding portion. The electrical storage device according to claim 1 or 2, wherein the junction is formed from a wall surface to a bottom surface in the concave portion of the lead. The electrical storage device according to any one of claims 1 to 3, wherein the first width (w1) and the fifth width (w5) satisfy a relationship of w1 > w5. The electrical storage device according to any one of claims 1 to 4, wherein the periphery of the joint is surrounded by a rectangle circumscribing an opening rim of the concave portion when viewed from a plane from the thickness direction of the lead. The electrical storage device according to any one of claims 1 to 5, wherein when viewed from the thickness direction of the lead, the junction exists in a rectangle circumscribing the opening edge of the concave portion of the lead. . 7. The semiconductor device according to any one of claims 1 to 6, characterized in that the concave portion is cut along the thickness direction of the lead along the direction of the first width (w1) And an angle? Formed by the imaginary straight line is 0 to 2.62 rad. The electrical storage device according to claim 7, wherein the depth D (mm) of the concave portion and the angle? (Rad) satisfy a relation of 0.25? (? + 1) / D. 9. A power storage device according to any one of claims 1 to 8, wherein the power storage device is configured as a lithium ion capacitor. And an electrode body having a positive electrode and a negative electrode each having an active material layer formed on a current collector and stacked with a separator interposed therebetween, at least one of the current collectors having an uncoated portion in which the active material layer is not formed, A method of manufacturing a power storage device in which a junction to be joined is formed,
A step of preparing a lead in which a thin portion is formed by having a concave portion,
And joining the flat portion to the thin portion by the concave portion by welding so as to form the joint portion. The method of manufacturing a power storage device according to claim 10, wherein the welding is laser welding. 11. The semiconductor device according to claim 10 or 12, wherein the concave portion is cut along the thickness direction of the lead along the direction perpendicular to the direction in which the lead extends, and the two virtual straight lines extending along the wall surface of the concave portion Wherein the angle? Is from 0 to 2.62 rad.

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