WO2013001792A1

WO2013001792A1 - Electrode plate for electrochemical element, method for manufacturing electrode plate for electrochemical element, and electrochemical element

Info

Publication number: WO2013001792A1
Application number: PCT/JP2012/004127
Authority: WO
Inventors: 心原口
Original assignee: パナソニック株式会社
Priority date: 2011-06-29
Filing date: 2012-06-26
Publication date: 2013-01-03
Also published as: JP2014170614A

Abstract

Provided are an electrode plate for an electrochemical element, wherein an electrode plate main body and an electrode lead are highly strongly bonded to each other, a method for manufacturing such electrode plate, and an electrochemical element. This electrode plate for an electrochemical element includes: an electrode plate main body, which includes a laminated body of a strip-shaped current collector containing a metal, and active material layers, which are formed on the surfaces of the current collector, and contain an active material; a metal-containing electrode lead, which is disposed on a part of the surfaces of the active material layers; and a melting section, which electrically connects the electrode plate main body and the electrode lead to each other at one end portion of the electrode plate main body. The melting section contains an alloy composed of at least an active material and the metal component of the electrode lead.

Description

Electrode element electrode plate, method for producing the same, and electrochemical element

The present invention relates to an electrode plate for an electrochemical element, a method for manufacturing the same, and an electrochemical element, and more particularly, to an improved bonding state between an electrode plate and an electrode lead.

In recent years, portable electronic devices have become smaller and lighter, and as a power source for such electronic devices, demand for secondary batteries that are particularly small, light and high output among electrochemical elements is increasing. Among them, lithium ion secondary batteries and nickel metal hydride storage batteries have been actively developed because they have high energy density and high vibration resistance and impact resistance.

Such electrochemical devices such as secondary batteries and capacitors have a pair of electrode plates with different polarities inside, and the electrode plates are electrically connected via external terminals such as sealing plates and electrode leads. Connected to. The electrode plate usually has a structure in which active material layers are formed on both surfaces of a metal foil as a current collector. The electrode plate having such a structure is provided with a current collector exposed portion on which an active material layer is not formed at an appropriate interval in order to connect strip-shaped metal pieces as electrode leads. .

Thus, the electrical connection between the electrode plate and the electrode lead is conventionally performed by connecting the current collector and the electrode lead. This is because if it is attempted to connect the electrode plate and the electrode lead through the active material layer, it is difficult to ensure sufficient electrical connection. The current collector exposed portion (that is, the uncoated portion of the active material layer) is prepared without applying the electrode slurry containing the active material, or formed after the electrode slurry is applied, for example. It is manufactured by removing a part of the film (see Patent Document 1 and Patent Document 2).

Also, a method of electrically connecting the exposed end face of the current collector and the end face of the electrode lead at the end face of the electrode plate by plasma welding or the like has been proposed. (See Patent Document 3)

Japanese Patent Laid-Open No. 5-13064 Japanese Patent Laid-Open No. 1-265452 JP 2010-157484 A

When the active material layer is formed using the electrode slurry as in Patent Document 1 and Patent Document 2, for example, the electrode slurry is intermittently applied to the current collector surface, or the electrode slurry is continuously applied. After coating, by removing a part of the formed coating film, an uncoated portion of the active material layer for connecting the electrode leads can be easily formed. However, the width of the uncoated portion needs to be larger than the width of the electrode lead. Therefore, the amount of the active material is reduced due to the presence of the uncoated portion, which is an obstacle to increase the capacity.

In recent years, in addition to the method of forming an active material layer by applying electrode slurry, there is a method of forming an active material layer by depositing an active material containing silicon, germanium, tin, or the like on the surface of a current collector by vapor deposition or the like. Attention has been paid. When the active material layer is formed by deposition, it is not necessary to use a binder, unlike when the active material layer is formed using the electrode slurry. In addition, since the active material layer formed by deposition is integrally and densely formed on the surface of the current collector, the conductivity of the active material layer and the current collector is increased, and the conductive material included in the active material layer can be reduced, Can be eliminated. For this reason, it is possible to increase the capacity while reducing the thickness of the electrode.

However, when an active material layer is formed by deposition, it is very complicated not to partially form the active material layer, and it is substantially impossible to partially remove the formed active material layer. Is impossible. That is, in the case of a deposited film, it is difficult to form the current collector exposed portion on the current collector surface.

In the method of Patent Document 3, heat is mainly applied to the electrode lead to weld the current collector exposed portion on the current collector end surface and the end surface of the electrode lead. Therefore, even when the active material layer is a deposited film, the current collector and the electrode lead can be electrically connected.
However, in the method of Patent Document 3, the melted portion formed by welding between the current collector exposed portion and the electrode lead includes an alloy of the metal component of the electrode lead and the metal component of the current collector. The alloy of the metal component of an electrode lead and an active material is not included. Also, the size of the melted part is small. Furthermore, since the active material is not melted, an active material layer exists between the current collector and the electrode lead, and the bonding area between the current collector and the electrode lead becomes very small. As a result, the welding strength is reduced, and there is a problem that the fracture of the melted portion tends to occur after welding.

An object of the present invention is to provide an electrode plate for an electrochemical element in which an electrode plate body and an electrode lead are bonded with high strength, a method for manufacturing the same, and an electrochemical element.

One aspect of the present invention is an electrode plate body including a laminate of a strip-shaped current collector containing a metal and an active material layer formed on the surface of the current collector, and a part of the active material layer The electrode lead including the metal disposed on the surface of the electrode, and at one end of the electrode plate body, the electrode plate body and the electrode lead are provided with a melting portion that electrically connects, and the melting portion includes at least an active material The present invention also relates to an electrode plate for an electrochemical element including an alloy with a metal component of an electrode lead.

Another aspect of the present invention is a step of preparing an electrode plate body including a laminate of a band-shaped current collector containing a metal and an active material layer formed on the surface of the current collector and containing an active material; In the step of arranging the electrode lead so that one end of the electrode plate main body and one end of the electrode lead containing metal are close to a part of the surface of the active material layer, and one end of the electrode plate main body, At least the end surface of the active material layer and the end surface of the electrode lead are welded to at least contain an alloy of at least the active material and the metal component of the electrode lead, and the electrode plate body and the electrode lead are electrically connected. And a step of forming a melted portion. The method of manufacturing an electrode plate for an electrochemical element.

Still another aspect of the present invention is the above-described electrode plate for an electrochemical element as a first electrode, a second electrode having a polarity opposite to the first electrode, and between the first electrode and the second electrode. The present invention relates to an electrochemical element including a separator interposed between the two.

In the present invention, when the electrode plate main body and the electrode lead are electrically connected to each other at the one end portion of the electrode plate main body including the laminate of the current collector and the active material layer, the molten portion is at least active. It includes an alloy of the material and the metal component of the electrode lead. As a result, the electrode plate body and the electrode lead can be joined with high strength at one end of the electrode plate body, despite being connected to the electrode lead.

While the novel features of the invention are set forth in the appended claims, the invention will be further described by reference to the following detailed description, taken in conjunction with the other objects and features of the invention, both in terms of construction and content. It will be well understood.

FIG. 1 is a cross-sectional view schematically showing a configuration of an electrode plate for an electrochemical element according to an embodiment of the present invention. FIG. 2 is a perspective view schematically showing a configuration of the electrode plate for an electrochemical element in FIG. FIG. 3 is a perspective view schematically showing a configuration of an electrode plate for an electrochemical element and a separator according to an embodiment of the present invention. FIG. 4 is a perspective view schematically showing a configuration of an electrode plate for an electrochemical element and a separator according to an embodiment of the present invention. FIG. 5 is a perspective view schematically showing a configuration of an electrode plate for an electrochemical element according to another embodiment of the present invention. FIG. 6 is a perspective view schematically showing a configuration of an electrode plate for an electrochemical element according to still another embodiment of the present invention. FIG. 7 is a schematic cross-sectional view showing a conventional electrode plate for an electrochemical element. FIG. 8 is a schematic cross-sectional view showing a conventional electrode plate for an electrochemical element. FIG. 9 is a longitudinal sectional view schematically showing a nonaqueous electrolyte secondary battery according to an embodiment of the present invention. FIG. 10 is an X-ray diffraction spectrum at a specific position of the melted portion in the electrode plate for an electrochemical element of Example 1.

Hereinafter, embodiments of the present invention will be described with reference to the drawings as necessary.
(Electrode plate for electrochemical element and electrochemical element)
An electrode plate for an electrochemical device according to the present invention includes an electrode plate body including a laminate of a strip-shaped current collector containing metal and an active material layer formed on the surface of the current collector and containing an active material, and an active material An electrode lead including a metal disposed on a part of the surface of the layer, and a melting portion that electrically connects the electrode plate main body and the electrode lead at one end of the electrode plate main body. The melting part includes at least an alloy of the active material and the metal component of the electrode lead.

FIG. 1 is a schematic cross-sectional view showing a configuration of an electrode plate for an electrochemical element according to an embodiment of the present invention. FIG. 2 is a perspective view schematically showing a configuration of the electrode plate for an electrochemical element in FIG. The electrode plate body 1 includes a laminate of a strip-shaped current collector 1b containing metal, such as a metal foil, and an active material layer 1a formed on both surfaces of the current collector 1b. The active material layer 1a is formed over the entire surface of the current collector 1b. However, the active material layer 1a is not formed on the end face of the current collector 1b, and the current collector 1b is exposed. An electrode lead 2 containing a metal such as a metal foil is adjacent to one end of the electrode plate main body 1 and one end of the electrode lead 2 on a part of the surface of one active material layer 1 a of the electrode plate main body 1. Are arranged as follows.

In FIG. 1, at one end of the electrode plate main body 1, a melting portion 3 including an alloy of at least an active material and a metal component of the electrode lead 2 among the constituent components of the electrode plate main body 1 is formed. The melting part 3 physically connects and electrically joins the electrode plate body 1 and the electrode lead 2 at one end of the electrode plate body 1. The melting part 3 is formed at one end of the electrode lead 2 in the longitudinal direction. In the electrochemical element, the electrode lead 2 is connected to an external terminal or the like. Further, in FIG. 1, the thickness of the melted portion 3 in the thickness direction of the laminated body is equal to or greater than the total thickness of the laminated body and the electrode lead 2.

On the other hand, in the conventional method such as Patent Document 3, since heat concentrates on the electrode lead, even if the end surface of the current collector and the end surface of the electrode lead are welded to form the melted portion, the melted portion is slightly It is only formed by melting the current collector that melts into the electrode lead and the electrode lead. For this reason, the molten part includes an alloy of the metal component of the current collector and the metal component of the electrode lead, but does not include an alloy of the active material and the metal component of the electrode lead. A schematic cross-sectional view of an electrode plate for an electrochemical element formed by such a conventional method is shown in FIGS.

In FIG. 7, the electrode plate body 1 includes a laminate of a strip-shaped current collector 1b containing metal and an active material layer 1a formed on both surfaces of the current collector 1b. An electrode lead 2 containing a metal is disposed on a part of the surface of one active material layer 1a of the electrode plate body 1 so that one end portion of the electrode plate body 1 and one end portion of the electrode lead 2 are close to each other. ing. The one end portion of the electrode plate main body 1 is formed with a melting portion 3a formed by welding the end surface of the current collector 1b and the end surface of the electrode lead 2. In addition, the fusion | melting part 3a is formed in the one end part of the longitudinal direction of the electrode lead 2 similarly to the case of FIG.

Thus, since the melting part 3a is merely formed by melting the end face of the current collector 1b and the end face of the electrode lead 2, it does not contain an alloy of the active material and the metal component of the electrode lead. Further, since the melting amount of the constituent components of the current collector 1b and the electrode lead 2 is small, the size of the melting portion 3a is reduced. Therefore, the thickness of the melted part 3 a in the thickness direction of the laminated body does not exceed the total thickness of the laminated body and the electrode lead 2. In such a method, as shown in FIG. 7, the melting part 3 a is sandwiched between the current collector 1 b and the electrode lead 2 so as to bridge the end surface of the current collector 1 b and the end surface of the electrode lead 2. It is only formed in a state where it is adhered to the end face of the active material layer 1a. As shown in FIG. 7, when the electrode plate body 1 has the active material layer 1a on both surfaces of the current collector 1b, the end surface of the active material layer sandwiched between the current collector and the electrode lead is Although it is covered with the melting part, it is difficult to cover the end face of the other active material layer 1a with the melting part. For this reason, it is difficult to increase the bonding strength between the electrode plate body and the electrode lead by the conventional method.

Further, even in the conventional method, if the welding is performed so that the melting amount of the electrode lead is increased, the thickness of the molten portion can be increased. Such an example is shown in FIG. FIG. 8 is a schematic cross-sectional view showing a conventional electrode plate for an electrochemical element.

In FIG. 8, the electrode plate body 1 includes a laminate of a current collector 1b and an active material layer 1a formed on both surfaces of the current collector 1b, as in FIG. At one end of the electrode plate main body 1, a melted part 3 b formed by welding the end face of the current collector 1 b and the end face of the electrode lead 2 is formed. In FIG. 8, the thickness of the melted part 3b in the thickness direction of the laminated body becomes larger than the thickness of the laminated body by mainly melting the electrode lead 2 so that the amount of melting of the electrode lead 2 is increased. Yes.

However, even in the conventional method as shown in FIG. 8, since the electrode lead 2 is mainly melted, the active material having a high melting temperature is difficult to melt and is not alloyed. Therefore, even if the thickness of the melted part 3b is increased so that the entire end face of the laminate can be covered at one end of the electrode plate body, the electrode lead 2 is formed only on the end face of the laminate (especially the active material layer) In addition, it is difficult to increase the bonding strength because it is in a state of being joined to the electrode plate body 1 via the melted portion 3b formed in a state of being in contact with only the end surface of the active material layer.

On the other hand, in the present invention, the melting part is formed by welding at least one end face of the active material layer and one end face of the electrode lead at one end of the electrode plate body. When the end surface of the active material layer is mainly melted, the active material contained in the active material layer is easily melted, and the elements contained in the active material are contained in the electrode lead or the current collector. can do. As a result, melting of the electrode lead and the current collector can be promoted, so that the melting efficiency between the active material and the metal component of the electrode lead and the melting efficiency of the current collector and the metal component of the electrode lead can be increased. it can.

Therefore, as the amount of melting of the metal component of the active material and the current collector and the metal component of the electrode lead increases, the size of the melted portion increases as shown in FIG. 1 and FIG. As a result, the thickness of the melted portion is increased to be equal to or greater than the total thickness of the laminate and the electrode lead. That is, the active material and the constituent components of the electrode lead are alloyed to form a melted portion, and at one end of the electrode plate body, the entire end surface of the laminate is covered with the melted portion in the thickness direction of the laminate. Become. Therefore, the electrode plate body and the electrode lead can be joined with high strength, and for example, it is possible to ensure a high welding strength that is higher than the breaking strength of the electrode plate body.

Further, in the present invention, even when the electrode plate main body has active material layers on both surfaces of the current collector, the end surfaces of the active material layers on both surfaces and the electrode leads are melted. Part can be formed. Therefore, as shown in FIG. 1 and FIG. 2, not only the end surface of the active material layer 1 a sandwiched between the current collector 1 b and the electrode lead 2 but also the end surface of the other active material layer 1 a Can be covered. Accordingly, the entire laminate of the electrode plate main body and the electrode lead can be firmly bonded.

In the present invention, by melting the end surface of the active material layer, the melting efficiency of the active material and the metal component of the electrode lead, and further the melting efficiency of the metal component of the current collector and the metal component of the electrode lead are increased. Can do. For this reason, a large amount of energy is not consumed for welding although a large melted portion can be formed to ensure high joint strength. That is, it is possible to ensure high bonding strength with low energy consumption. For example, when plasma welding is performed, the number of irradiation of energy rays required for welding can be reduced.

The melting part includes an alloy of the constituent components of the electrode plate body other than the active material and the metal components of the electrode lead. As a component of the electrode plate body, when the active material layer includes a metal component as a conductive material, a metal component as the conductive material, a metal component of a current collector, and the like can be given. In other words, the alloy in the molten part can include at least an alloy of the active material and the metal component of the electrode lead, and the active material, the metal component of the conductive material and / or the current collector, and the metal component of the electrode lead. Alloys may be included.

The thickness of the melted portion in the thickness direction of the laminate is equal to or greater than the total thickness of the laminate and the electrode lead, and is preferably larger than the total thickness of the laminate and the electrode lead. The thickness of the melted part is, for example, 180 μm or more, preferably 200 μm or more, and more preferably 250 μm or more.
In the electrochemical element, the electrode plate for an electrochemical element as the first electrode is opposed to the second electrode having the opposite polarity to the first electrode, and a separator is provided between the first and second electrodes. Use with the intervening.

3 and 4 are perspective views schematically showing the configuration of the electrode plate for an electrochemical element and the separator. FIG. 3 shows a mode in which the separator 4 is disposed on the surface of the electrode plate for an electrochemical element in FIG. 2 on the electrode lead 2 side. FIG. 4 shows an aspect in which the separator 4 is disposed on the surface of the electrode plate for an electrochemical element of FIG. 2 on the electrode lead 2 side and on the surface of the active material layer 1a on the side not in contact with the electrode lead 2. Indicates.

As shown in FIG. 3 and FIG. 4, the thickness of the melted part is the thickness of the electrode plate (first electrode) and the thickness of the separator disposed in contact with one surface or both surfaces of the electrode plate. The total thickness may be less than or equal to the total thickness. The thickness of the melted part is, for example, 500 μm or less, preferably 450 μm or less, more preferably 400 μm or less or 300 μm or less.

In an electrochemical element, there may be used an electrode group formed by winding or laminating an electrode plate (first electrode) with a second electrode facing a second electrode. In such a case, when the thickness of the melted portion is set to be equal to or less than the total thickness of the electrode plate and the separator, it is possible to more effectively suppress the separator from being broken or deformed. Thereby, the internal short circuit in an electrochemical element can be suppressed. In this case, the melted part is joined to one end of the electrode plate, but not joined to the end face of the separator.

1 to 4 show an example in which a melted part is formed at one end in the longitudinal direction of the electrode lead. However, the present invention is not limited to such an example, and a melted part is formed at one end in the short direction of the electrode lead. A part may be formed. FIG. 5 is a perspective view schematically showing a configuration of an electrode plate for an electrochemical element according to another embodiment of the present invention. In FIG. 5, the electrode lead 2 is disposed so that one end portion in the short direction and one end portion of the electrode plate body 1 are close to each other, and the melting portion 3 includes the end surface in the short direction of the electrode lead 2, It is formed by welding the active material layer 1 a of the plate body 1.

The active material layer melts at least the end face, but is melted not only to the end face but also to a portion sandwiched between the current collector and the electrode lead. When the active material layer melts to such a portion, it becomes possible to secure a higher bonding strength.

That is, in the present invention, the melted portion formed at one end in the longitudinal direction or the short direction of the electrode lead not only has a large thickness in the thickness direction of the laminate, but also the longitudinal direction or the short side of the electrode lead. The length in the direction is also increased.

The molten part contains an alloy containing the constituent elements of the active material, but does not contain the active material itself. Further, the melted part is formed at one end of the active material layer. Therefore, the length of the melted portion can be restated as the length of the region not including the active material from one end portion of the electrode lead.

The length of the melted part (for example, the length in the longitudinal direction or the short direction of the electrode lead) is, for example, 250 μm or more or 300 μm or more, preferably 350 μm or more, and more preferably 400 μm or more. The upper limit of the length of the melted part is, for example, 700 μm or less, preferably 600 μm or less, and more preferably 550 μm. These lower limit value and upper limit value can be appropriately selected and combined. The length of the melted part may be, for example, 300 to 600 μm or 400 to 700 μm.

On the other hand, when the molten part is formed by welding the end face of the current collector and the end face of the electrode lead by a conventional method, the active material layer hardly melts. As shown in FIG. 5, the length is shorter, for example, less than 150 μm.

When the melted part is formed by a conventional method, the active material layer hardly melts, so even if the X-ray diffraction spectrum of the melted part is measured, the peak derived from the alloy of the active material and the metal component of the electrode lead is Almost no detection. On the other hand, in the present invention, a peak derived from an alloy of the active material and the metal component of the electrode lead is detected in the X-ray diffraction spectrum at any position of the fusion zone.

Therefore, the difference between the melted portion formed by the conventional method and the melted portion in the present invention is the presence or absence of a peak derived from an alloy of the active material in the melted portion and the metal component of the electrode lead in the X-ray diffraction spectrum. It can also be confirmed by the difference.

For example, in the electrode plate of the present invention, when the X-ray diffraction spectrum is measured at a position 150 μm from the extreme end of the melted part in the longitudinal direction or the short direction of the electrode lead, the active material and the metal component of the electrode lead The peak derived from the alloy can be confirmed. The depth at which the X-ray diffraction spectrum is measured is not particularly limited, and may be measured at a position that is half the thickness of the melted portion in the thickness direction of the laminate. You may measure at (that is, shallow position). Here, the endmost part is the endmost part on the side opposite to the electrode lead body of the melting part.

In a preferred embodiment, the X-ray diffraction spectrum is measured at any position 150 μm from the shortest part of the melted part in the longitudinal direction or short-side direction of the electrode lead, and the alloy of the active material and the metal component of the electrode lead is obtained. The derived peak can be detected.

In the embodiment of FIGS. 1 to 5, an example is shown in which a melted part is formed at one location of one end of the electrode plate body. However, the present invention is not limited to such an example, and at least one What is necessary is just to form a fusion | melting part and you may form two or more fusion | melting parts. FIG. 6 is a perspective view schematically showing a configuration of an electrode plate for an electrochemical element according to still another embodiment of the present invention. In FIG. 6, two melting portions 3 are formed at one end in the longitudinal direction of the electrode lead 2, and the electrode plate body 1 and the electrode lead 2 are joined by these melting portions 3. In FIG. 6, it is the same as that of the structure of FIG. 2 except that the two fusion | melting parts 3 are formed. The number of melted parts is not limited to one or two, and may be three or more.

Further, the melted portion does not necessarily have to be formed in a spot shape as shown in FIGS. 1 to 6, and covers the whole or most of the end surface of the electrode lead in the width direction at one end of the electrode plate body. You may form in a wide shape (for example, strip | belt shape).
The welding strength can be further increased by forming a plurality of melted portions at one end of the electrode plate body or by forming the melted portions into a wide shape such as a band shape.
The electrode plate of the present invention is useful as an electrode plate for various electrochemical elements because of high bonding strength between the electrode lead and the electrode plate body.

The electrochemical element includes the above-described electrode plate for an electrochemical element as a first electrode, a second electrode having a polarity opposite to the first electrode, and a separator interposed between the first electrode and the second electrode. Including.
Examples of the electrochemical element in which the electrode plate is used include a battery and a capacitor (for example, an electric double layer capacitor) having a current collecting structure similar to that of the secondary battery. Examples of the battery include primary batteries such as alkaline dry batteries and lithium primary batteries, alkaline secondary batteries such as nickel hydride storage batteries, and secondary batteries such as non-aqueous electrolyte secondary batteries (such as lithium ion secondary batteries).

Below, each component of an electrode plate and an electrochemical element is demonstrated.
The electrode plate main body included in the electrode plate includes a laminate of a current collector containing metal and an active material layer formed on the surface and containing an active material.

In the present invention, since the molten portion is formed by alloying the metal component of the electrode lead and at least the active material (preferably, the metal component of the active material and the current collector), the electrode lead can be alloyed. The combination of the metal contained in the metal and the metal contained in the active material or current collector may be selected as appropriate. The type of metal contained in the electrode lead, the metal contained in the current collector, and the active material can be either the type of electrochemical element or the type of electrode on which the electrode plate is used (positive electrode (or anode) or negative electrode (or cathode)). )) And so on.

Examples of the metal contained in the electrode lead include copper, copper alloy, nickel, nickel alloy, aluminum, aluminum alloy, silver, silver alloy, gold, and gold alloy. Of these, copper or a copper alloy is preferable.

The metal contained in the current collector is selected according to the type of electrochemical element or the type of electrode, and examples thereof include copper, copper alloy, nickel, nickel alloy, aluminum, aluminum alloy, and stainless steel.

Examples of the active material include metals that can be alloyed with the above-described metals contained in the current collector, alloys of these metals, metal compounds, and the like, and are selected according to the type of electrochemical element, the type of electrode, and the like.

The electrode plate of the present invention is particularly useful for use in non-aqueous electrolyte secondary batteries such as lithium ion batteries among electrochemical elements. The constituent elements of the electrochemical device will be described below by taking a nonaqueous electrolyte secondary battery as an example.

The nonaqueous electrolyte secondary battery includes a positive electrode, a negative electrode, a separator interposed therebetween, and a nonaqueous electrolyte.
In the nonaqueous electrolyte secondary battery, the electrode plate of the present invention is preferably used as a negative electrode.
The negative electrode includes a current collector and an active material layer formed on the surface of the current collector. The active material layer may be formed on one surface of the current collector, or may be formed on both surfaces.

Examples of the material of the negative electrode current collector include copper and copper alloys. The form of the negative electrode current collector is not particularly limited, and may be a nonporous metal foil or may be porous. The thickness of the negative electrode current collector can be selected from a range of 5 to 50 μm, for example.

The negative electrode active material layer may be formed of a negative electrode active material, and may contain a binder, a conductive agent, a thickener, and the like in addition to the negative electrode active material.
Examples of the negative electrode active material include various materials that can be alloyed with the metal component of the electrode lead and that can reversibly occlude and release lithium ions, such as silicon, silicon alloys, silicon compounds (silicon oxide SiOx, silicon nitride). Alloy, silicon carbide, etc.), tin, tin alloys, tin compounds (tin oxide SnOx, tin nitride, tin carbide, etc.), and alloy materials such as lithium alloys containing Al, Zn and / or Mg, etc. It can be illustrated. In silicon oxide and tin oxide, the coefficient x is 0 <x <2.

Examples of the silicon alloy include an alloy containing silicon and lithium, an alloy containing Al, Zn, and / or Mg in addition to silicon and lithium.
Examples of the tin alloy include an alloy containing tin and lithium, an alloy containing Al, Zn, and / or Mg in addition to tin and lithium.
These negative electrode active materials can be used individually by 1 type or in combination of 2 or more types.
Of the negative electrode active materials, silicon, silicon alloys, silicon compounds, and the like are particularly preferable. Among these, an alloy containing at least silicon and lithium is preferable.

From the viewpoint of increasing the melting efficiency of the active material, a lithium foil or a lithium alloy foil may be attached to the surface of the negative electrode active material layer in the negative electrode active material layer. Lithium contained in the attached lithium foil or alloy foil is appropriately occluded in the negative electrode active material layer.

The electrode lead electrically connected to the negative electrode preferably contains copper or a copper alloy.
For example, an electrode lead including copper or a copper alloy and an electrode plate main body including an alloy containing lithium and an element such as silicon or tin as an active material are welded to one end of the electrode plate main body. In this case, when the active material contains lithium, the melting temperature becomes lower than that of silicon or tin alone, and the melting easily proceeds. Therefore, when the melted part is formed so as to mainly melt the active material layer, the melted silicon or tin diffuses into the copper or copper alloy contained in the electrode lead. When silicon or tin diffuses into copper or a copper alloy, the melting temperature becomes lower than the melting temperature of the original copper or copper alloy, so that the melting is further facilitated. That is, by mainly melting the active material layer, the melting of the active material is facilitated and the melting efficiency of the metal component of the electrode lead is further increased. Thereby, the melting amount of the active material and the electrode lead is increased, and the size of the melted portion is increased.

Moreover, since the negative electrode current collector also contains copper and a copper alloy, as in the case of the electrode lead, like the alloying of the active material and the metal component of the electrode lead, the current collector copper and copper alloy, Alloying with the active material, and hence the electrode lead, is likely to proceed. Therefore, the amount of melting of the current collector is also increased, and the size of the melted portion is further increased.

Moreover, in the case of such alloying, not only the end surfaces of the active material layer, the current collector and the electrode lead but also a part of the end surface side are alloyed together. Therefore, the bonding strength can be greatly increased.

The melted portion thus formed contains an alloy of copper and silicon or tin. In a preferred embodiment, the molten part contains an alloy of copper and silicon. The composition of such an alloy is not particularly limited, but the alloy preferably contains Cu ₅ Si.

Alloy containing Cu ₅ Si has the X-ray diffraction spectrum, the peak derived from the Cu ₅ Si, around 2 [Theta] = 68 ° and around 153 °. Since the peak near 2θ = 68 ° is higher in intensity than the peak near 2θ = 153 °, the presence or extent of Cu ₅ Si is examined by confirming the peak near 2θ = 68 °. be able to.
When the melted part is formed by welding the end face of the current collector and the end face of the electrode lead by a conventional method, peaks at around 2θ = 68 ° and around 153 ° are hardly observed in the X-ray diffraction spectrum. .

The negative electrode active material layer can be formed using a negative electrode slurry containing a negative electrode active material, a binder, and a dispersion medium. The negative electrode slurry may further contain a thickener, a conductive material, and the like as necessary. The negative electrode active material layer can be formed by preparing a negative electrode slurry containing these components and applying it to the surface of the negative electrode current collector.
Depending on the type of the negative electrode active material, a negative electrode active material is deposited on the surface of the current collector by a vapor deposition method such as a vacuum vapor deposition method, a sputtering method, or a CVD method to form a thin film of the negative electrode active material. Thus, a negative electrode active material layer may be formed.

As binders, fluorine resins such as polyvinylidene fluoride (PVDF); acrylic resins such as polymethyl acrylate and ethylene-methyl methacrylate copolymer; rubbers such as styrene-butadiene rubber, acrylic rubber, or modified products thereof The material can be exemplified.
The ratio of the binder is, for example, 0.1 to 10 parts by mass, preferably 1 to 5 parts by mass, per 100 parts by mass of the active material.

Examples of the dispersion medium contained in the negative electrode slurry include water, alcohols such as ethanol, ethers such as tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), or a mixed solvent thereof.

The negative electrode slurry can be prepared by a method using a conventional mixer such as a planetary mixer or a disperser. The negative electrode slurry can be applied to the surface of the negative electrode current collector by, for example, a conventional application method using various coaters. The coating film of the negative electrode slurry is usually dried and subjected to rolling.

Examples of the conductive agent include carbon black; conductive fibers such as metal fibers and carbon fibers; and carbon fluoride. The ratio of the conductive agent is, for example, 0.1 to 7 parts by mass per 100 parts by mass of the active material.

Examples of the thickener include cellulose derivatives such as carboxymethyl cellulose (CMC); poly C _2-4 alkylene glycol such as polyethylene glycol. The ratio of the thickener is, for example, 0.1 to 10 parts by mass per 100 parts by mass of the active material.
The thickness of the negative electrode active material layer is, for example, 5 to 200 μm, preferably 5 to 100 μm. The thickness of the negative electrode active material layer formed by deposition is, for example, 5 to 50 μm or 5 to 30 μm.

The positive electrode includes a current collector and an active material layer formed on the surface of the current collector. The active material layer may be formed on one surface of the current collector, or may be formed on both surfaces.
Examples of the material of the positive electrode current collector include stainless steel, aluminum, aluminum alloy, and titanium. The form and thickness of the positive electrode current collector are the same as those of the negative electrode current collector.

The positive electrode active material layer may contain a binder, a conductive agent, a thickener and the like in addition to the positive electrode active material. The positive electrode active material layer can be formed by a method similar to that of the negative electrode active material layer, using a positive electrode slurry containing these components. As each component contained in a positive electrode slurry, what was illustrated by the term of the negative electrode slurry can be used, and content of each component can be selected from the same range as the case of a negative electrode slurry. The thickness of the positive electrode active material layer can be selected from the same range as the thickness of the negative electrode active material layer.

As the positive electrode active material, known nonaqueous electrolyte secondary battery positive electrode active materials can be used, and among these, lithium transition metal oxides are preferably used. A positive electrode active material can be used individually by 1 type or in combination of 2 or more types.

As the lithium transition metal oxide, specifically, for example, Li _x M ^a _1-y M ^b _y O ₂ (0.9 ≦ x ≦ 1.1, 0 ≦ y ≦ 0.7, M ^a is Ni , Co, Mn, Fe, at least one selected from the group consisting of Ti or the like, M ^b other such as at least one metal element) other than M ^a _{_{_{is, LiMn 2 O 4, LiFePO 4}}} , LiCoPO 4, LiMnPO ₄ and so on.

As the lithium transition metal oxide, for example, lithium cobaltate and a modified product thereof, lithium nickelate and a modified product thereof, lithium manganate and a modified product thereof are preferable. Examples of such a lithium transition metal oxide, of the above _{_{formula, Li x Ni 1-y M}} c y O 2 (0.9 ≦ x ≦ 1.1,0 ≦ y ≦ 0.7, M c is Li _x Co ₁₋ , represented by lithium nickel oxide represented by at least one selected from the group consisting of Co, Mn, Fe, Ti, Al, Mg, Ca, Sr, Zn, Y, Yb, Nb, and As) _y M ² _y O ₂ (0.9 ≦ x ≦ 1.1, 0 ≦ y ≦ 0.7, M ² is Ni, Mn, Fe, Ti, Al, Mg, Ca, Sr, Zn, Y, Yb , At least one selected from the group consisting of Nb and As).

In the lithium nickel oxide, y is preferably 0.05 ≦ y ≦ 0.5. In the lithium cobalt oxide, y is preferably 0 ≦ y ≦ 0.3.
Among the lithium transition metal oxides of the above formula, LiNi _1/2 Mn _1/2 O ₂ , LiNiO ₂ , LiNi _1/2 Fe _1/2 O ₂ , LiNi _0.8 Co _0.15 Al _0.05 O ₂ , LiNi _1/3 Mn _1/3 Co _1/3 O ₂ , LiCoO ₂ , LiMnO _{2 and the} like are preferable.

As the separator, a resin-made microporous film, a nonwoven fabric, a woven fabric, or the like, or an inorganic porous film based on a filler such as a metal oxide can be used. The separator may be a laminate of a plurality of porous layers. Each porous layer can be formed of a single-layer separator such as a microporous film, and a plurality of different types of porous layers may be combined. Examples of the resin constituting the microporous film and the nonwoven fabric separator include polyolefins such as polyethylene and polypropylene; polyamide; polyamideimide; polyimide; cellulose and the like. The inorganic porous film includes a filler and a resin binder that binds the filler.
The thickness of the separator is, for example, 5 to 100 μm or 5 to 50 μm.

In the non-aqueous electrolyte secondary battery, a non-aqueous electrolyte having lithium ion conductivity is used as the non-aqueous electrolyte. The non-aqueous electrolyte includes a non-aqueous solvent and a lithium salt dissolved in the non-aqueous solvent.

Non-aqueous solvents include cyclic carbonates such as propylene carbonate and ethylene carbonate (EC); chain carbonates such as diethyl carbonate, ethylmethyl carbonate (EMC) and dimethyl carbonate; cyclic esters such as γ-butyrolactone and γ-valerolactone Examples thereof include carboxylic acid esters. These non-aqueous solvents can be used alone or in combination of two or more.

Examples of the lithium salt include LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiC (SO ₂ CF ₃ ₃ ). A lithium salt can be used individually by 1 type or in combination of 2 or more types. The concentration of the lithium salt in the nonaqueous electrolyte is, for example, 0.5 to 1.8 mol / L.

A known additive such as a vinylene carbonate compound such as vinylene carbonate may be added to the non-aqueous electrolyte.

The nonaqueous electrolyte secondary battery can be manufactured by a known method according to the shape of the battery. In a cylindrical battery or a rectangular battery, for example, a positive electrode, a negative electrode, and a separator disposed between them are wound to form an electrode group, and the electrode group and the electrolyte can be accommodated in a battery case. .

The electrode group is not limited to a wound one, but may be a laminated one or a folded one. The shape of the electrode group may be a cylindrical shape or a flat shape having an oval end surface perpendicular to the winding axis, depending on the shape of the battery or battery case.

As the battery case material, aluminum, an aluminum alloy (such as an alloy containing a trace amount of a metal such as manganese or copper), a steel plate, or the like can be used.

FIG. 9 is a longitudinal sectional view schematically showing a cylindrical nonaqueous electrolyte secondary battery according to an embodiment of the present invention.
The cylindrical non-aqueous electrolyte secondary battery 10 includes a bottomed cylindrical battery case 16, an electrode group 14 accommodated in the battery case 16, and a non-aqueous electrolyte (not shown). Sealed with a sealing body 18.

More specifically, the electrode group 14 is formed by winding the positive electrode 11 and the negative electrode 12 in a vortex shape with a separator 13 interposed therebetween. The electrode group 14 is housed inside the battery case 16 with the upper insulating plate 15a disposed on the upper surface and the lower insulating plate 15b disposed on the bottom surface.

The positive electrode lead 11 a led out from the upper part of the electrode group 14 is electrically connected to a sealing body 18 that seals the opening of the battery case 16. On the other hand, the negative electrode lead 12 a led out from the lower part of the electrode group 14 is electrically connected to the inner bottom surface of the battery case 16. At this time, the negative electrode lead 12a is a molten portion formed by welding the end surface of the negative electrode active material layer included in the negative electrode 12 and the end surface of the negative electrode lead 12a at one end portion of the negative electrode 12 of the electrode group 14. And are electrically connected.

The nonaqueous electrolyte is injected into the battery case 16 after the electrode group 14 is stored in a predetermined amount. After injecting the nonaqueous electrolyte, a sealing body 18 having a sealing gasket 17 attached to the periphery is inserted into the opening of the battery case 16. And the nonaqueous electrolyte secondary battery 10 can be obtained by crimping and sealing so that the opening part of the battery case 16 may be bent inward.

(Method for producing electrode plate for electrochemical element)
The method for producing an electrode plate for an electrochemical element used as an electrode for a nonaqueous electrolyte secondary battery includes the following steps (i) to (iii).
(I) a step of preparing an electrode plate body including a laminate of a band-shaped current collector containing a metal and an active material layer formed on the surface of the current collector and containing an active material;
(Ii) a step of arranging the electrode lead so that one end of the electrode plate main body and one end of the electrode lead containing metal are close to a part of the surface of the active material layer; and (iii) the electrode plate main body At least one end portion of the active material layer and the end surface of the electrode lead are welded to each other, thereby including an alloy of at least the active material and the metal component of the electrode lead, and the electrode plate body and the electrode lead. And a step of forming a melting portion to be electrically connected.
And in the said manufacturing method, the thickness of the fusion | melting part in the thickness direction of a laminated body shall be more than the total thickness of a laminated body and an electrode lead.

In step (i), the electrode plate body can be prepared by laminating an active material layer on the surface of the current collector to form a laminate. A laminated body can be formed according to the formation method of the negative electrode in said nonaqueous electrolyte secondary battery.

In step (ii), electrode leads are arranged on a part of the surface of the active material layer of the electrode plate body prepared in step (i). At this time, the electrode lead is placed on the surface of the active material layer so that one end of the electrode plate body and one end of the electrode lead containing metal are close to each other so that a melted part can be easily formed in the next step (iii). Deploy. In the next step (iii), at least the end surface of the active material layer and the end surface of the electrode lead in the electrode plate main body are welded. Therefore, in step (ii), at least the end surface of the active material layer and the end surface of the electrode lead are Make it close. At this time, the end faces of the current collector may be brought close together with these end faces.

In step (ii), the electrode lead may be arranged so that one end in the longitudinal direction and one end of the electrode plate main body are close to each other. As shown in FIG. You may arrange | position so that the one end part of a board main body may adjoin. In a preferred embodiment, one end of the electrode lead in the longitudinal direction and one end of the electrode plate main body are brought close to each other.

In step (iii), at least one end surface of the active material layer and an end surface of the electrode lead are welded to one end portion of the electrode plate body to form a melted portion. In the present invention, in the step (iii), a molten part including at least an active material and a metal component of the electrode lead among the constituent components of the electrode plate body is formed. And let the thickness of the fusion | melting part formed be more than the total thickness of a laminated body and an electrode lead. Therefore, as described above, the electrode plate body and the electrode lead can be bonded with extremely high bonding strength.

The welding method is not particularly limited, and a known welding method for joining the electrode lead and the electrode plate body can be employed. Specific examples include arc welding such as TIG welding, plasma welding, and covering arc welding; electron beam welding; laser welding. Among these welding methods, arc welding, particularly non-consumable electrode type arc welding such as TIG welding and plasma welding, particularly plasma welding is preferable.
In addition, the mechanism in which a fusion | melting part is formed by welding is as above-mentioned.

EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example and a comparative example, this invention is not limited to a following example.
Example 1
A lithium ion secondary battery electrode plate having the structure shown in FIG. 1 was produced as follows.
A laminated body was formed by forming a 20 μm thick active material layer 1a by vacuum-depositing silicon oxide on both surfaces of a 40 μm thick copper foil as the current collector 1b.

Furthermore, in order to improve the melting efficiency, lithium foil having a thickness of 10 μm was pasted on the surfaces of both active material layers 1a. Subsequently, the laminated body to which the lithium foil was attached was cut into a strip shape having a length of 300 mm and a width of 60 mm to produce an electrode plate body 1 having a thickness of 80 μm. Then, an electrode lead 2 made of copper having a thickness of 100 μm, a length of 90 mm, and a width of 5 mm is disposed on the surface of one active material layer 1a of the electrode plate main body 1, on one end in the longitudinal direction of the electrode lead 2, and the electrode plate main body 1 was arranged so as to be close to one end.

Next, at one end of the electrode plate body 1, the end surface of the electrode plate body 1 and the end surface of the electrode lead 2 are welded by mainly melting the active material layer 1a of the electrode plate body 1 by plasma welding. One melting part 3 was formed in a spot shape. As shown in FIG. 1, the melting portion 3 is formed at one end portion of the electrode plate body 1 so as to cover the entire end surface of the laminate and the electrode lead in a state where the one end portion is melted.

(Example 2)
As shown in FIG. 6, when plasma welding the end surface of the electrode plate body 1 and the end surface of the electrode lead 2 at one end portion of the electrode plate body 1, the two melted portions 3 are formed in a spot shape. In the same manner as in Example 1, the electrode plate body 1 and the electrode lead 2 were joined.

(Comparative Example 1)
As shown in FIG. 7, at one end of the electrode plate main body 1, the electrode lead 2 is mainly melted by plasma welding to weld the end face of the electrode plate main body 1 and the end face of the electrode lead 2 to melt. The electrode plate body 1 and the electrode lead 2 were joined in the same manner as in Example 1 except that the portion 3a was formed.

(Comparative Example 2)
As shown in FIG. 8, at one end of the electrode plate body 1, the end surface of the electrode plate body 1 and the end surface of the electrode lead 2 are welded by melting mainly the electrode lead 2 by plasma welding. The electrode plate body 1 and the electrode lead 2 were joined in the same manner as in Example 1 except that the portion 3b was formed.

(Comparative Example 3)
An electrode plate body 1 was prepared in the same manner as in Example 1.

(Example 3)
Fifteen electrode plates prepared in Examples 1 and 2 and Comparative Examples 1 and 2 were prepared for each Example and Comparative Example, and the following evaluation was performed.

(1) Thickness and length of melted part For five of the 50 electrode plates in each example, an electron micrograph of a cross section in the thickness direction of the laminate of the electrode plates was taken, and the thickness of the laminate The average value of the thickness of the melted part in the direction was determined.
Moreover, in the electron micrograph of the cross section, the average value of the length of the melted portion in the longitudinal direction of the electrode lead was determined.

(2) Tensile strength and fracture state in tensile test The bonding strength between the electrode plate body and the electrode lead was evaluated by the following procedure.
Of the 50 electrode plates in each example, the tensile strength in the melted part was measured for 5 of them. Specifically, the electrode plate is set on the tensile tester so that the electrode plate main body and the electrode lead are pulled respectively, and at a constant speed, the axial direction of the tensile tester, specifically, the electrode plate main body And the electrode lead were pulled away from each other. And the load (tensile strength) when a welding part fractured | ruptured was evaluated as joining strength.
In the tensile test, the state of the fractured portion was visually observed.

(3) State of separator after winding For each example, five electrode plates were wound together with the separator, and the presence or absence of breakage or deformation of the separator in the vicinity of the melted portion was observed.

(4) About the composition of the fusion zone A scanning electron microscope (3D real surface view) is equipped with an energy dispersive X-ray analyzer (trade name: Genesis XM2, manufactured by EDAX), and copper and silicon in the cross section of the fusion zone The elemental map of was investigated.

Next, with respect to the cross section of the melted portion, it was melted at 150 μm from the extreme end of the melted portion in the longitudinal direction of the electrode lead using a microscopic X-ray diffractometer (trade name: RINT2500, manufactured by Rigaku Corporation). The X-ray diffraction spectrum was measured at a position 100 μm from the uppermost end of the part (depth of the melted part 100 μm). Based on the X-ray diffraction spectrum, qualitative analysis of the components contained in the melted part was performed.
The evaluation results are shown in Table 1.

As shown in Table 1, in Examples and Comparative Example 2, the thickness of the melted portion in the thickness direction of the laminated body was all 200 μm or more. On the other hand, in Comparative Example 1, the thickness of the melted part was smaller than the thickness of the laminate.
In Examples, a high tensile strength of 0.5 N was obtained in all cases.

From the element map of copper and silicon, copper and silicon were present in almost all areas of the cross section of the melted part in the examples. Moreover, as a result of measuring the element molar ratio of copper and silicon at a predetermined position of the melted part, copper was 90 mol% and silicon was 10 mol%. From these results, it was found that silicon diffused in copper to form an alloy.

Further, from the results of analysis by X-ray diffraction spectrum of the cross section of the melted portion, in all of the examples, the copper peaks in the melted portion are near 2θ = 66 °, 2θ = 78 ° and 2θ = 128 °. Was confirmed. In addition, in the vicinity of 2θ = 68 ° and 2θ = 153 °, peaks derived from the alloy Cu ₅ Si of the active material and the metal component of the electrode lead were confirmed. Note that such a peak derived from Cu ₅ Si was 150 μm from the extreme end of the melted portion 3 in the longitudinal direction of the electrode lead 2, and was confirmed at any depth position. Thus, in the embodiment, it was found that contain Cu ₅ Si alloy to the molten portion.

From the above analysis results, it has been clarified that in the electrode plate of the example, copper and a copper-silicon alloy containing Cu ₅ Si exist in the molten part. Therefore, in the embodiment where the electrode plate body and the electrode lead were welded mainly by melting the active material layer, a large amount of silicon diffused in the copper, the melting efficiency increased, and the molten part expanded. It is guessed.

As described above, in the embodiment, an alloy of the constituent component of the electrode plate body and the metal component of the electrode lead is formed in the melting portion, and the thickness of the melting portion is equal to or greater than the total thickness of the laminate and the electrode lead. It has become. Therefore, it is considered that a tensile strength as high as 0.5 N was obtained in any of the examples.

Further, in the examples, the fractured part by the tensile test was not the melted part but the current collector part. From this also, it is considered that the alloy contained in the melted part has a great influence on the tensile strength. It can be inferred that the tensile strength of the example depends on the tensile strength of the electrode plate body itself, and the tensile strength of the melted portion has higher welding strength than the tensile strength of the electrode plate body itself.

On the other hand, in Comparative Examples 1 and 2 in which the copper lead was mainly melted to form the melted portion, the peak derived from Cu ₅ Si was not confirmed in the analysis result of the X-ray diffraction spectrum of the melted portion. Therefore, it can be seen that in Comparative Examples 1 and 2, alloying of copper contained in the electrode lead and silicon contained in the active material does not occur and the melting efficiency is low.

In Comparative Examples 1 and 2, the active material is not melted, and the melted portion is attached to the end face of the active material layer, so that the bonding strength between the electrode plate body and the electrode lead cannot be increased. In addition, since the active material layer exists very close to one end of the electrode plate body, it is difficult to firmly weld the electrode lead and the current collector. Therefore, even in the case where the thickness of the melted portion is larger than the thickness of the laminate as in Comparative Example 2, the welding strength is not so different from that in Comparative Example 1.

In the embodiment, when an alloy of copper and silicon is formed in the melted portion, melting of the electrode lead and the active material is promoted, and the melted portion is considerably enlarged. On the other hand, in Comparative Example 1, since the size of the melted portion is smaller than the thickness of the laminated body of the electrode plate body and the electrode lead, it is surmised that the alloying of copper and silicon hardly progressed.

Thus, in Comparative Examples 1 and 2, the alloying of copper and silicon hardly proceeds, and the melted portion hardly contains an alloy of copper and silicon. Therefore, in these comparative examples, the tensile strength was low, and the sample was fractured with a load smaller than the value of 0.5 N in the example. In these comparative examples, it was confirmed that the current collector was not broken and was broken at the melted portion.

Regarding the state of the separator after winding, in Comparative Example 2, the separator was broken and deformed in the vicinity of the melted portion. Further, in Example 1, the separator was slightly broken and deformed in the vicinity of the melted portion, but in Example 2, no breakage and deformation of the separator were observed.

From the above, with respect to the examples of the present invention, it was possible to confirm the effect of improving the welding strength as compared with the conventional examples. In particular, regarding Example 2, since it has high welding strength and the separator was not confirmed to be broken, it can be presumed that the short-circuit suppressing effect is also high.

Although the present invention has been described in terms of the presently preferred embodiments, such disclosure should not be construed as limiting. Various changes and modifications will no doubt become apparent to those skilled in the art to which the present invention pertains after reading the above disclosure. Accordingly, the appended claims should be construed to include all variations and modifications without departing from the true spirit and scope of this invention.

The electrode plate for an electrochemical element of the present invention is suitable for use as an electrode in various batteries such as a non-aqueous electrolyte secondary battery and various electrochemical elements such as a capacitor. An electrochemical element including an electrode plate for an electrochemical element is suitable for large current discharge, for example, a driving power source for a power tool or an electric vehicle that requires high output, a large-capacity backup power source, a power storage This is useful for power supplies. In addition, the electrochemical element can be used for applications such as a driving power source in various portable electronic devices such as a mobile phone, a notebook personal computer, and a video camcorder, and a large power source in a household power storage device.

DESCRIPTION OF SYMBOLS 1 Electrode plate main body 1a Active material layer 1b Current collector 2

Electrode lead

3, 3a, 3b Melting part 4, 13 Separator 10 Nonaqueous electrolyte secondary battery 11 Positive electrode 11a Positive electrode lead 12 Negative electrode 12b Negative electrode lead 14 Electrode group 15a Upper insulating plate 15b Lower insulating plate 16 Battery case 17 Sealing gasket 18 Sealing plate

Claims

An electrode plate body comprising a laminate of a strip-shaped current collector containing metal and an active material layer formed on the surface of the current collector and containing an active material;
An electrode lead including a metal disposed on a part of the surface of the active material layer, and a melting portion that electrically connects the electrode plate body and the electrode lead at one end of the electrode plate body. And
The molten part is an electrode plate for an electrochemical element, containing at least an alloy of the active material and a metal component of the electrode lead.
The active material is at least one selected from the group consisting of silicon, silicon alloys and silicon compounds;
The metal component of the electrode lead is copper or a copper alloy;
The electrode plate for an electrochemical element according to claim 1, wherein the molten part contains an alloy of silicon and copper.
The electrode plate for an electrochemical element according to claim 2, wherein the alloy of silicon and copper contains Cu 5 Si.
When the X-ray diffraction spectrum of the melted part is measured at any position of 150 μm from the extreme end of the melted part, it has a peak derived from the alloy of silicon and copper in the vicinity of 2θ = 68 °. The electrode plate for electrochemical elements according to claim 2 or 3.
The active material layer is formed on both surfaces of the current collector,
The electrode for an electrochemical element according to any one of claims 1 to 4, wherein the melting part is formed by melting the end faces of the active material layer on both surfaces of the current collector and the electrode lead. Board.
The electrode plate for an electrochemical element according to any one of claims 1 to 5, wherein a thickness of the melted portion in a thickness direction of the laminate is equal to or greater than a total thickness of the laminate and the electrode lead. .
The electrode plate for an electrochemical element according to any one of claims 1 to 6, wherein the melted portion has a length of 300 µm or more.
A step of preparing an electrode plate body including a laminate of a strip-shaped current collector containing a metal and an active material layer formed on the surface of the current collector and containing an active material;
Arranging the electrode lead so that one end of the electrode plate main body and one end of the electrode lead containing metal are close to a part of the surface of the active material layer;
At least one end surface of the active material layer and an end surface of the electrode lead are welded at one end of the electrode plate main body to include at least an alloy of the active material and the metal component of the electrode lead; and The manufacturing method of the electrode plate for electrochemical elements which comprises the process of forming the fusion | melting part which electrically connects an electrode plate main body and the said electrode lead.
The method for producing an electrode plate for an electrochemical element according to claim 8, wherein the thickness of the melted portion in the thickness direction of the laminate is equal to or greater than the total thickness of the laminate and the electrode lead.
The method for producing an electrode plate for an electrochemical element according to claim 8 or 9, wherein an end face of the active material layer and an end face of the electrode lead are welded by plasma welding.
The electrode plate for an electrochemical element according to any one of claims 8 to 10, wherein the welding is performed mainly by melting the active material layer between the electrode lead and the current collector. Production method.
The electrode plate for an electrochemical element according to any one of claims 1 to 7, as a first electrode,
A second electrode having a polarity opposite to that of the first electrode;
An electrochemical device comprising a separator interposed between the first electrode and the second electrode.
The electrochemical element according to claim 12, comprising an electrode group obtained by winding or laminating the first electrode and the second electrode with the separator interposed therebetween.
The electrochemical element according to claim 12 or 13, wherein a thickness of the melting part is equal to or less than a total thickness of the first electrode and the separator.