WO2021049376A1 - Battery, electronic device, and electric tool - Google Patents

Abstract

A battery that comprises a wound electrode body (20) and an outer case (11) housing the wound electrode body. The wound electrode body has a configuration having, wound in the longitudinal direction: a band-shaped first electrode (21) that has a first lead (25) and a first bondable film material (28); a band-shaped second electrode (22); and a band-shaped separator (23) provided between the first electrode and the second electrode. The first electrode (21) has a first collector exposed section (21C) in which a first active substance layer (21B) is not provided, positioned between both ends of the first electrode in the longitudinal direction. The first lead (25) is provided in the first collector exposed section (21C) such that one end side thereof protrudes from a long side of the first electrode. In the first lead, the length (Wh2) of a section facing one or both the separator (23) and/or the second electrode (22) is shorter than 50% of the width (W2) of the second electrode. The first bondable film material (28) is provided in a region of the first collector exposed section that does not have the first lead provided therein.

Description

Batteries, electronics and power tools

The present invention relates to a battery, an electronic device including the battery, and a power tool.

Cylindrical winding type non-aqueous electrolyte secondary battery is used as a power supply source for various devices such as power tools and electric vehicles. A strong impact may be applied to such equipment from the outside, which may cause damage or deformation of the battery. Among the cylindrical batteries, the vicinity of the central portion in the cylindrical axial direction of the battery is more likely to be deformed by an external force than other portions. Therefore, regarding the performance of the battery, it is desired to improve the impact resistance near the central portion of the battery.

By the way, the cylindrical battery has a structure in which a wound electrode body obtained by winding an electrode laminate in which a pair of electrodes are laminated via a separator is housed in an outer body. The wound electrode body is formed with a structural portion in which a part of the reed is overlapped and joined on the surface of the current collector at the center of the electrode in the longitudinal direction of the electrode, and this structural portion affects the performance of the battery. Various research and development are being carried out in consideration of the possibility of giving. In the present specification, regardless of whether the positive electrode or the negative electrode is used, the longitudinal direction of the electrode means the direction that is the longitudinal direction of the electrode in the state of the electrode laminate in the non-wound state.

For example, Patent Document 1 describes a battery in which a positive electrode lead is welded to a portion where an active material of a positive electrode is partially removed, and the area to be removed is smaller than the total width of the opposing negative electrode. Is disclosed.

Patent Document 2 describes that in an electrode structure having an uncoated portion on the electrode on the winding start side, the thickness of the uncoated portion is 0.3 to 1.0 times the thickness of the electrode tab at a place where there is no electrode tab (lead). A battery characterized in that an insulating film is attached is disclosed.

Patent Document 3 is characterized in that, in an electrode structure having an uncoated portion as a part of the electrode, a lead bonded to the uncoated portion and a current collector foil are partially interposed by a protective layer such as a film. The battery is disclosed.

In Patent Document 4, an uncoated portion is provided on the winding end side of the positive electrode, a positive electrode lead and a negative electrode lead are arranged on the winding end side, and the length of the portion of the positive electrode lead facing the negative electrode is the negative electrode. A battery having a width of 1/2 or less is disclosed.

Jikkenhei 4-15156 JP-A-2010-108608 Japanese Unexamined Patent Publication No. 2014-89856 Japanese Unexamined Patent Publication No. 11-26023

In recent cylindrical batteries, from the viewpoint of obtaining a higher output, a current collector exposed in which an active material layer is not provided at the non-end portion of one of the pair of electrodes in the longitudinal direction. A structure is adopted in which a portion is formed and a lead is joined to the exposed portion of the current collector. In a battery having such a structure, deformation near the central portion on the peripheral surface of the battery causes an internal short circuit (short circuit) of the battery due to destruction of the current collector near the contact portion with the lead in the current collector. May cause. Further, in the structure in which the lead is joined to the exposed portion of the current collector formed at the non-end portion of the electrode, the structural distortion of the wound electrode body when winding the pair of electrodes laminated via the separator It is also important to be able to suppress the unwinding. For these reasons, in a cylindrical battery, it is required to further improve the impact resistance of the battery in the vicinity of the central portion on the peripheral surface of the battery and to suppress the unwinding more effectively. .. The impact resistance of the battery in the present specification means that the occurrence of an internal short circuit (short circuit) of the battery when an impact is applied to the battery is suppressed.

In response to such a request, for all the batteries described in Patent Documents 1 to 4, the battery having a structure in which the current collector exposed portion is formed at the non-end portion of the electrode is improved in impact resistance and wound. There was room for further improvement in terms of achieving both suppression of unwinding of the electrode body.

Therefore, an object of the present invention is to provide a battery capable of improving impact resistance and suppressing unwinding of the wound electrode body, an electronic device having the battery, and a power tool.

The present invention
Winding electrode body and
Equipped with an outer can for storing the wound electrode body,
The wound electrode body is provided between the band-shaped first electrode having the first reed and the first adhesive film material, the band-shaped second electrode, and the first electrode and the second electrode. It has a structure in which the strip-shaped separator is wound in the longitudinal direction.
The first electrode has a first current collector exposed portion to which the first active material layer is not provided between both ends in the longitudinal direction of the first electrode.
The first lead is provided on the exposed portion of the first current collector so that one end side protrudes from the long side side of the first electrode.
The length of the portion of the first lead facing either or both of the separator and the second electrode is shorter than 50% of the width of the second electrode.
The first adhesive film material is a battery provided in a region of the first exposed part of the current collector where the first reed is not provided.

Further, the present invention may be an electronic device or a power tool having the above-mentioned battery.

According to the present invention, it is possible to improve the impact resistance of the battery and suppress the unwinding of the wound electrode body of the battery.

FIG. 1 is a schematic cross-sectional view showing an example of the configuration of a secondary battery according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of the electrode laminate. FIG. 3A is a schematic plan view showing one of the examples of the configuration of the positive electrode forming the battery according to the embodiment of the present invention. FIG. 3B is a schematic cross-sectional view showing a schematic state of the vertical cross section of the line IIIB-IIIB of FIG. 3A and an enlarged view of a portion of the region X1 surrounded by the alternate long and short dash line. 3C and 3D are schematic plan views showing one of the other examples of the configuration of the positive electrode forming the battery according to the embodiment of the present invention. FIG. 4A is a schematic plan view showing one of the examples of the configuration of the negative electrode forming the battery according to the embodiment of the present invention. FIG. 4B is a schematic cross-sectional view showing an outline of the state of the vertical cross section of the IVB-IVB line of FIG. 4A. FIG. 4C is a schematic plan view showing one of the other examples of the configuration of the negative electrode forming the battery according to the embodiment of the present invention. FIG. 4D is a schematic cross-sectional view showing an outline of the state of the vertical cross section of the IVD-IVD line of FIG. 4C. FIG. 5A is a schematic plan view for explaining a laminated state of the positive electrode and the negative electrode. FIG. 5B is a schematic cross-sectional view for explaining an enlarged state of a part of the cross section of the wound electrode body. FIG. 6 is a diagram for explaining an application example. FIG. 7 is a diagram for explaining another application example. FIG. 8 is a diagram for explaining another application example.

Embodiments of the present invention will be described in the following order.
<One Embodiment>
<Example>
<Application example>
<Modification example>
The embodiments and the like described below are suitable specific examples of the present invention, and the contents of the present invention are not limited to these embodiments and the like.

<One Embodiment>
[Battery configuration]
Hereinafter, an example of the configuration of the cylindrical secondary battery (hereinafter, simply referred to as “battery”) according to the embodiment of the present invention will be described with reference to FIG. This battery is, for example, a lithium ion secondary battery in which the capacity of the negative electrode is represented by a capacity component due to occlusion and release of lithium (Li), which is an electrode reactant. The cylindrical battery is wound by winding an electrode laminate in which a pair of strip-shaped positive electrodes 21 and strip-shaped negative electrodes 22 are laminated via a separator 23 inside a substantially hollow cylindrical battery can 11 which is an outer can. A rotating electrode body 20 (hereinafter, simply referred to as “electrode body 20”) is provided. The battery can 11 is made of nickel (Ni) plated iron (Fe), one end of which is closed and the other end of which is open. An electrolytic solution as a liquid electrolyte is injected into the inside of the battery can 11, and the first electrode, the second electrode (positive electrode 21, negative electrode 22) and the separator 23 are impregnated. Further, a pair of insulating plates 12 and 13 are arranged perpendicular to the winding peripheral surface so as to sandwich the electrode body 20.

At the open end of the battery can 11, a battery lid 14, a safety valve mechanism 15 provided inside the battery lid 14, and a heat-sensitive resistance element (Positive Temperature Cofficient; PTC element) 16 are interposed via a sealing gasket 17. It is attached by being crimped. As a result, the inside of the battery can 11 is sealed. The battery lid 14 is made of the same material as the battery can 11. The safety valve mechanism 15 is electrically connected to the battery lid 14, and when the internal pressure of the battery exceeds a certain level due to an internal short circuit or heating from the outside, the disk plate 15A is inverted and the battery lid 14 and the electrode It is designed to disconnect the electrical connection with the body 20. The sealing gasket 17 is made of an insulating material, and the surface is coated with asphalt.

The electrode body 20 has a substantially columnar shape. The electrode body 20 has a center hole 20A penetrating from the center of the first end face toward the center of the second end face. The central hole 20A functions as a flow path that guides the gas from the can bottom side of the battery can 11 to the battery lid 14 side opposite to the gas when gas is generated in the battery can 11.

When the first electrode is the positive electrode and the second electrode is the negative electrode, the first lead is the positive electrode lead 25, and the second lead corresponds to the negative electrode lead 26 and the negative electrode lead 27. The positive electrode lead 25 connected to the positive electrode 21 is formed of aluminum (Al) or the like, and the negative electrode leads 26 and 27 connected to the negative electrode 22 are formed of nickel or the like.

The first lead is bonded to the first electrode, and the second lead is bonded to the second electrode. When the first electrode is a positive electrode, as shown in FIG. 1, the positive electrode lead 25 as the first lead is electrically connected to the battery lid 14 by being welded to the safety valve mechanism 15. The negative electrode leads 26 and 27 as the second leads are welded to the battery can 11 and electrically connected. When the first electrode is the negative electrode, the first reed is welded to the battery can 11 and electrically connected, and the second reed joined to the second electrode is welded to the safety valve mechanism 15. ..

In the battery, either the first electrode or the second electrode may correspond to the positive electrode 21, but in the following, as shown in the examples of FIGS. 1 to 5, the first electrode is the positive electrode 21 and the second electrode. It is explained that the electrode 2 corresponds to the negative electrode 22. Then, referring to FIGS. 1, 2, 3A, 3B, 3C, 3D, 4A, 4B, 4C, 4D, 5A, and 5B, the positive electrode 21, the negative electrode 22, and the separator 23 , And the electrolytic solution will be described in sequence. Note that FIG. 5A is a diagram for explaining a state in which the positive electrode 21 shown in FIG. 3A and the negative electrode 22 shown in FIG. 4A are laminated, and the description of the separator 23 is omitted for convenience of explanation. Further, FIG. 5B is a diagram for explaining the state of the cross section of the portion where the positive electrode lead is arranged in a part of the electrode body 20 formed by winding the electrode laminate having the laminated structure shown in FIG. 5A.

(Positive electrode)
The positive electrode 21 is, for example, a positive electrode current collector 21A as a first current collector and a positive electrode active material layer as a first active material layer provided on both main surfaces 21S and 21S of the positive electrode current collector 21A. It is equipped with 21B. The positive electrode current collector 21A is made of, for example, a metal foil such as an aluminum foil, a nickel foil, or a stainless steel foil. The positive electrode active material layer 21B contains one or more positive electrode active materials capable of occluding and releasing lithium. The positive electrode active material layer 21B may further contain at least one of a binder and a conductive agent, if necessary.

(Exposed part of positive electrode current collector)
As shown in FIGS. 3A and 3B, the positive electrode active material layer 21B was not provided at the predetermined positions of both main surfaces 21S and 21S of the positive electrode 21, and the positive electrode current collector 21A was exposed. A positive electrode current collector exposed portion 21C is provided as a portion. In the examples of FIGS. 3A and 3B, the positive electrode current collector exposed portion 21C is formed over the entire width in the width direction of the positive electrode 21. Specifically, the positive electrode current collector exposed portion 21C includes a non-end portion of the positive electrode 21 in the longitudinal direction of the positive electrode 21 (in the direction of the double-headed arrow X in FIGS. 3 and 5), more specifically, an end portion on the winding center side. It is formed in the portion between the ends on the outer peripheral side of the winding. In the example shown in FIGS. 3A and 3B, the positive electrode current collector exposed portion 21C is provided near the central portion of the positive electrode 21 in the longitudinal direction of the positive electrode 21. A positive electrode lead 25 is provided on the positive electrode current collector exposed portion 21C formed on a part of one main surface 21S of the positive electrode 21. In FIGS. 3 to 5, the longitudinal directions of the positive electrode 21 and the negative electrode 22 are indicated by double-headed arrows X, and the width directions of the positive electrode 21 and the negative electrode 22 are indicated by double-headed arrows Y.

In the example shown in FIGS. 3A and 3B, the number of the positive electrode current collector exposed portions 21C was one, but as shown in FIGS. 3C and 3D, there are a plurality of positive electrode current collector exposed portions 21C. A positive electrode lead 25 may be provided on each of the positive electrode current collector exposed portions 21C that are formed. When a plurality of positive electrode current collector exposed portions 21C are formed, all the positive electrode current collector exposed portions 21C may be formed at the non-end portions of the positive electrode 21 in the longitudinal direction of the positive electrode 21 as shown in FIG. 3D. As shown in FIG. 3C, the positive electrode current collector exposed portion 21C may be formed at the end of the positive electrode 21 in the longitudinal direction of the positive electrode 21. When a plurality of positive electrode current collector exposed portions 21C are formed, positive electrode leads may be provided on the plurality of positive electrode current collector exposed portions 21C as shown in FIG. 3D. Further, in the examples of FIGS. 3A and 3B, the positive electrode current collector exposed portion 21C is formed on both main surfaces at one non-end portion of the positive electrode 21, but even if it is formed on one main surface. Good.

(Arrangement of positive electrode leads)
The positive electrode lead 25 is joined to the positive electrode current collector exposed portion 21C in a state where a part thereof overlaps with the positive electrode current collector exposed portion 21C, and a part of the positive electrode lead 25 is formed by the electrode body 20. When formed, it faces the negative electrode 22 via the separator 23. One end of the positive electrode lead 25 projects from the long side of the positive electrode 21, and the other end (appropriately referred to as an inner end) is arranged in a direction toward the inside of the positive electrode 21. The same applies to the negative electrode lead described later.

The length of the portion of the positive electrode lead 25 facing either one or both of the separator 23 and the negative electrode 22 (that is, the end of the portion facing the negative electrode 22 or the separator 23 from the inner end portion 25A of the positive electrode lead). The length to the outer end portion 25B (indicated by the reference numeral Wh2 in FIG. 5B) is smaller than 50% of the width of the negative electrode 22 (indicated by the reference numeral W2 in FIG. 5A). By arranging the positive electrode leads 25 in this way, when the electrode body 20 is housed in the battery can 11, the positive electrode leads 25 are in the tubular axial direction of the battery can 11 (indicated by double-headed arrows Sh in FIG. 1). It becomes easy to arrange the battery can 11 in a position avoiding the vicinity of the center of the battery can 11. Therefore, even if an impact is applied toward the center of the battery near the center of the outer peripheral surface of the battery and the battery is deformed, the positive electrode current collector is near the contact portion between the positive electrode lead 25 and the positive electrode current collector 21A. It is possible to suppress the possibility that the 21A is destroyed, which in turn induces the destruction of the separator 23 and causes an internal short circuit of the battery, and the impact resistance of the battery can be improved.

From the viewpoint of further improving the impact resistance of the battery, it is more preferable that the length Wh2 of the positive electrode leads 25 is 45% or less of the width W2 of the negative electrode 22.

However, if the length Wh2 of the positive electrode leads 25 is too short, the length of the portion of the positive electrode leads 25 that overlaps the exposed portion 21C of the positive electrode current collector (indicated by the reference numeral Wh1 in FIG. 5A) becomes too short, and the positive electrode leads There is a risk that the 25 cannot be reliably joined by the positive electrode current collector exposed portion 21C. From the viewpoint of improving the bondability between the positive electrode lead 25 and the positive electrode current collector exposed portion 21C, the length Wh1 of the portion of the positive electrode lead 25 that overlaps the positive electrode current collector exposed portion 21C is the width of the positive electrode 21 (reference numeral in FIG. 5A). It is preferably 10% or more of the length (shown by W1). However, if the length Wh1 of the portion of the positive electrode lead 25 that overlaps the exposed portion 21C of the positive electrode current collector is too long, the positive electrode current collector 21A is destroyed near the contact portion between the positive electrode lead 25 and the positive electrode current collector 21A. The length Wh1 of the portion of the positive electrode lead 25 that overlaps the exposed portion 21C of the positive electrode current collector is preferably smaller than 50% of the width W1 of the positive electrode 21 because the effect of preventing the positive electrode from being lost is diminished.

(Positive electrode bonding film material)
In the positive electrode current collector exposed portion 21C, the winding axis direction of the electrode body 20 with respect to the region where the positive electrode lead 25 is not provided, specifically, the inner end portion 25A of the positive electrode lead 25 (both in FIG. 5A). A positive electrode bonding film material 28 as a first film material is provided at a position facing the arrow R) (a position facing the inner end portion 25A). The separation distance between the positive electrode bonding film material 28 and the positive electrode lead 25 is not particularly limited, but the positive electrode bonding film material 28 is such that the positive electrode bonding film material 28 exists inside the exposed portion 21C of the positive electrode current collector. It is preferable that the separation distance between the positive electrode lead 25 and the positive electrode lead 25 is determined.

The positive electrode bonding film material 28 is composed of a film material provided with a base material and an adhesive layer, and is adhered to the positive electrode current collector exposed portion 21C via the adhesive layer.

In this embodiment, an insulating tape having a rectangular shape is used as the film material. Examples of the material of the base material constituting the film material include polyethylene terephthalate (PET), polyimide (PI), polyethylene (PE), polypropylene (PP) and the like.

Examples of the adhesive layer include a layer containing at least one of an acrylic adhesive, a silicone adhesive, and a urethane adhesive.

By providing not only the positive electrode lead 25 but also the positive electrode bonding film material 28 in the positive electrode current collector exposed portion 21C, it is possible to correct the unevenness in thickness due to the presence or absence of the positive electrode lead 25. When forming the electrode body 20, it becomes easy to suppress the occurrence of winding misalignment.

(Thickness of positive electrode bonding film material)
The thickness of the positive electrode adhesive film material 28 (indicated by reference numeral HF1 in FIG. 3B) can be appropriately selected, but from the viewpoint of more effectively obtaining the effect of suppressing the occurrence of winding misalignment, the positive electrode lead 25 It is preferably 20% or more of the thickness (indicated by reference numeral HL1 in FIG. 3B). If the thickness of the positive electrode bonding film material 28 becomes too thick, the electrode body 20 may locally bulge and the performance of the battery may deteriorate. Therefore, the thickness HF1 of the positive electrode bonding film material 28 is the positive electrode lead. It is preferably within the range of 120% or less of the thickness HL1.

(Positive current collector)
The positive electrode current collector 21A is made of, for example, a metal foil such as an aluminum foil, a nickel foil, or a stainless steel foil.

(Positive electrode active material layer)
The positive electrode active material layer 21B contains a positive electrode active material capable of occluding and releasing lithium as a first active material. The positive electrode active material layer 21B may further contain at least one of a binder and a conductive agent, if necessary.

(Positive electrode active material)
As the positive electrode active material capable of occluding and releasing lithium, for example, a lithium-containing compound such as a lithium oxide, a lithium phosphorus oxide, a lithium sulfide, or an interlayer compound containing lithium is suitable, and these two types are suitable. The above may be mixed and used. In order to increase the energy density, a lithium-containing compound containing lithium, a transition metal element, and oxygen (O) is preferable. Examples of such a lithium-containing compound include a lithium composite oxide having a layered rock salt type structure, a lithium composite phosphate having an olivine type structure, and the like. The lithium-containing compound is more preferably one containing at least one of the group consisting of cobalt (Co), nickel (Ni), manganese (Mn) and iron (Fe) as a transition metal element. Examples of the lithium-containing compound include a lithium composite oxide having a layered rock salt type structure, a lithium composite oxide having a spinel type structure, and a lithium composite phosphate having an olivine type structure.

Examples of the lithium composite oxide containing nickel include a lithium composite oxide containing lithium, nickel, cobalt, manganese and oxygen (NCM), and a lithium composite oxide containing lithium, nickel, cobalt, aluminum and oxygen (NCA). May be used.

The positive electrode active material capable of occluding and releasing lithium may be other than the above. In addition, two or more kinds of positive electrode active materials exemplified above may be mixed in any combination.

(binder)
As the binder, for example, polyvinylidene fluoride, polytetrafluoroethylene, polyacrylonitrile, styrene butadiene rubber, carboxymethyl cellulose, and at least one of these resin materials can be used.

(Conducting agent)
As the conductive agent, for example, at least one carbon material selected from the group consisting of graphite, carbon fiber, carbon black, acetylene black, ketjen black, carbon nanotubes, graphene and the like can be used. A metal material, a conductive polymer material, or the like may be used as the conductive agent. The shape of the conductive agent includes, for example, granular, scaly, hollow, needle-shaped, tubular, and the like, but is not particularly limited to these shapes.

(Negative electrode)
As shown in FIGS. 2, 4A to 4D, and FIG. 5, the negative electrode 22 is a negative electrode current collector 22A and a negative electrode active material layer as a second active material layer provided on both main surfaces 22S and 22S. It is equipped with 22B. The width of the negative electrode 22 is not particularly limited, but is generally longer than the width of the positive electrode 21 as shown in FIG. 5 and the like.

The negative electrode current collector 22A was exposed without providing the negative electrode active material layer 22B on a part of both main surfaces 22S and 22S at the central end of the negative electrode 22. An electric body exposed portion 22C is provided. In the example of FIGS. 4A to 4D, the negative electrode current collector exposed portion 22C is formed over the entire width in the width direction of the negative electrode 22.

A negative electrode lead 26 is provided on the negative electrode current collector exposed portion 22C provided on a part of the main surface 22S.

Negative electrode collection as a second current collector exposed portion, in which the negative electrode active material layer 22B is not provided on both main surfaces 22S and 22S of the winding outer peripheral end of the negative electrode 22 and the negative electrode current collector 22A is exposed. An electric body exposed portion 22D is provided. A negative electrode lead 27 is provided on the negative electrode current collector exposed portion 22D provided on a part of the main surface 22S. In the example of FIGS. 4A to 4D, the negative electrode current collector exposed portion 22D is formed over the entire width in the width direction of the negative electrode 22.

(Arrangement of negative electrode leads)
The negative electrode leads 26 and 27 are joined to the negative electrode current collector exposed portions 22C and 22D, respectively, in a state where a part of the negative electrode leads 26 and 27 overlap the negative electrode current collector exposed portions 22C and 22D.

In the examples of FIGS. 4A to 4D, the number of exposed negative electrode current collectors was multiple, but one exposed negative electrode current collector was formed, and negative electrode leads were provided in the exposed negative electrode current collectors. You may be. Further, in FIG. 4, the negative electrode current collector exposed portions 22C and 22D are formed on both main surfaces of both end portions (two locations) of the negative electrode 22, but may be formed on only one main surface.

As shown in FIG. 4C, the lengths Wz1 and Wz2 of the portions of the negative electrode leads 26 and 27 that overlap the exposed negative electrode current collectors 22C and 22D are preferably shorter than 50% or less of the width of the negative electrode. By arranging the negative electrode leads 26 and 27 in this way, when the electrode body 20 is housed in the battery can 11, the negative electrode leads 26 and 27 are located at the center of the battery can 11 in the tubular axial direction Sh of the battery can 11. It becomes easy to arrange it in a position avoiding the vicinity. Therefore, even when an impact is applied to the central position of the outer peripheral surface of the battery and the battery is deformed, the negative electrode current collector 22A or the like is formed near the contact portion between the negative electrode leads 26 and 27 and the negative electrode current collector 22A. It is possible to suppress the possibility that the battery will be broken and thereby cause an internal short circuit, and it is possible to improve the impact resistance of the battery.

From the viewpoint of further improving the impact resistance of the battery, the lengths Wz1 and Wz2 of the negative electrode leads 26 and 27 overlapping the exposed negative electrode current collectors 22C and 22D are 45% or less of the width W2 of the negative electrode 22. It is preferably a length.

However, if the length of the portion of the negative electrode leads 26 and 27 that overlaps the negative electrode is too short, the negative electrode leads 26 and 27 may not be reliably joined by the negative electrode current collector exposed portions 22C and 22D. From the viewpoint of forming a state in which the negative electrode leads 26 and 27 are securely joined by the negative electrode current collector exposed portions 22C and 22D, the length of the portion of the negative electrode leads 26 and 27 that overlaps the negative electrode current collector exposed portions 22C and 22D. It is preferable that Wz1 and Wz2 have a length of 10% or more of the width W2 of the negative electrode 22.

(Negative electrode bonding film material)
As shown in FIG. 4C, the negative electrode current collector exposed portion 22C is wound with a wound electrode body around a region where the negative electrode lead 26 is not provided, specifically, the inner end portion 26A of the negative electrode lead 26. The negative electrode bonding film material 29 as the second film material may be provided at a position facing the rotational axis direction (double arrow R in FIG. 4C) (position facing the inner end portion 26A). Further, as shown in FIG. 4C, the negative electrode current collector exposed portion 22D is also a wound electrode body with respect to the region where the negative electrode lead 27 is not provided, specifically, the inner end portion 27A of the negative electrode lead 27. The negative electrode bonding film material 30 as the second film material may be provided at a position facing the winding axis direction (double arrow R in FIG. 4C) (position facing the inner end portion 27A). The inner end portions 26A and 27A of the negative electrode leads 26 and 27 indicate the end portion of the negative electrode leads 26 and 27 that overlaps the negative electrode current collector exposed portions 22C and 22D. The separation distance between the negative electrode bonding film materials 29 and 30 and the negative electrode leads 26 and 27 is not particularly limited, but the negative electrode bonding film materials 29 and 30 are present inside the exposed negative electrode current collectors 22C and 22D, respectively. Therefore, it is preferable that the distance between the negative electrode bonding film materials 29 and 30 and the negative electrode leads 26 and 27 is determined.

The negative electrode bonding film materials 29 and 30 are composed of a film material provided with a base material and an adhesive layer, and are adhered to the negative electrode current collector exposed portions 22C and 22D via the adhesive layer. As the film material, a film material forming the positive electrode bonding film material 28 can be used, but a film material of a different material may be used.

When not only the negative electrode lead 26 but also the negative electrode bonding film material 29 is provided on the negative electrode current collector exposed portion 22C at the central end of the negative electrode 22, the electrode laminate is wound to form the electrode body 20. In addition, it becomes easy to suppress the possibility that the portion where the negative electrode lead 26 is installed locally bulges to the outside three-dimensionally and causes winding misalignment. Since not only the negative electrode lead 27 but also the negative electrode bonding film material 30 is provided on the negative electrode current collector exposed portion 22D at the outer peripheral end of the negative electrode 22, unevenness due to the negative electrode lead 27 occurs on the outer peripheral surface of the electrode body 20. It becomes difficult and the occurrence of distortion on the outer shape can be reduced.

(Thickness of negative electrode bondable film material)
The thickness of the negative electrode bondable film material 29 (reference numeral HF2 in FIG. 4D) can be appropriately selected, but from the viewpoint of more effectively obtaining the effect of suppressing the occurrence of winding misalignment, the thickness of the negative electrode lead 26 (FIG. 4D). In 4D, it is preferably 20% or more of the symbol HL2). If the thickness of the negative electrode bonding film material 29 becomes too thick, the electrode body 20 may locally bulge and the performance of the battery may deteriorate. Therefore, the thickness HF2 of the negative electrode bonding film material 29 is the negative electrode lead 26. It is preferable that the thickness is within the range of 120% or less of the thickness HL2. Although the negative electrode bonding film material 29 bonded to the negative electrode current collector exposed portion 22C has been described here, the same applies to the thickness of the negative electrode bonding film material 30 bonded to the negative electrode current collector exposed portion 22D. Yes, it is preferably 20% or more and 120% or less of the thickness of the negative electrode lead 27.

The negative electrode current collector 22A is made of, for example, a metal foil such as a copper foil, a nickel foil, or a stainless steel foil.

The negative electrode active material layer 22B contains a negative electrode active material capable of storing and releasing lithium. The negative electrode active material layer 22B may further contain at least one of a binder and a conductive agent, if necessary.

In the battery according to the present embodiment, the electrochemical equivalent of the negative electrode 22 or the negative electrode active material is larger than the electrolytic equivalent of the positive electrode 21, and theoretically, lithium metal does not precipitate on the negative electrode 22 during charging. It is preferable that

(Negative electrode active material)
Examples of the negative electrode active material include carbon materials such as non-graphitizable carbon, easily graphitizable carbon, graphite, pyrolytic carbon, coke, glassy carbon, calcined organic polymer compound, carbon fiber or activated carbon. Can be mentioned.

Further, as another negative electrode active material capable of increasing the capacity, a material containing at least one of a metal element and a metalloid element as a constituent element (for example, an alloy, a compound or a mixture) can be mentioned. By using such a material, a high energy density can be obtained. In particular, when used together with a carbon material, a high energy density can be obtained and excellent cycle characteristics can be obtained, which is more preferable. In the present invention, the alloy includes an alloy containing two or more kinds of metal elements and one or more kinds of metal elements and one or more kinds of metalloid elements. It may also contain non-metallic elements. Some of the structures include solid solutions, eutectic (eutectic mixtures), intermetallic compounds, or two or more of them coexist.

Examples of such a negative electrode active material include a metal element or a metalloid element capable of forming an alloy with lithium. Specific examples thereof include Mg, B, Al, Ti, Ga, In, Si, Ge, Sn, Pb, Bi, Cd, Ag, Zn, Hf, Zr, Y, Pd or Pt. These may be crystalline or amorphous. Among them, Si and Sn are preferable because they have a large ability to occlude and release lithium and can obtain a high energy density. Examples of such a negative electrode active material include a simple substance of Si, an alloy or a compound, a simple substance of Sn, an alloy or a compound, and a material having at least one or more of them.

Examples of Si alloys include Sn, Ni, Cu, Fe, Co, Mn, Zn, In, Ag, Ti, Ge, Bi, Sb, Nb, Mo, Al, as second constituent elements other than Si. Examples include those containing at least one selected from the group consisting of P, Ga and Cr. Examples of Sn alloys include Si, Ni, Cu, Fe, Co, Mn, Zn, In, Ag, Ti, Ge, Bi, Sb, Nb, Mo, Al, as second constituent elements other than Sn. Examples include those containing at least one selected from the group consisting of P, Ga and Cr.

Examples of the Si compound include those containing O or C as a constituent element. These compounds may contain the second constituent element described above.

Examples of other negative electrode active materials include metal oxides such as lithium titanate.

(binder)
As the binder, the same binder as that of the positive electrode active material layer 21B can be used.

(Conducting agent)
As the conductive agent, the same one as that of the positive electrode active material layer 21B can be used.

(Separator)
The separator 23 separates the positive electrode 21 and the negative electrode 22 and allows lithium ions to pass through while preventing a short circuit of current due to contact between the two electrodes. The separator 23 is porous, for example, made of polytetrafluoroethylene, polyolefin resin (polypropylene (PP), polyethylene (PE), etc.), acrylic resin, styrene resin, polyester resin or nylon resin, or a resin blended with these resins. It is composed of a quality film, and may have a structure in which two or more of these porous films are laminated.

In particular, polyethylene is preferable as a material constituting the separator 23 because it can obtain a shutdown effect in the range of 100 ° C. or higher and 160 ° C. or lower and is also excellent in electrochemical stability. The porous membrane may have a structure of three or more layers in which a polypropylene layer, a polyethylene layer, and a polypropylene layer are sequentially laminated. For example, it is desirable to have a three-layer structure of PP / PE / PP and have a mass ratio [wt%] of PP to PE of PP: PE = 60: 40 to 75:25. The method for producing the separator may be wet or dry.

As the separator 23, a non-woven fabric may be used. As the fibers constituting the non-woven fabric, aramid fibers, glass fibers, polyolefin fibers, polyethylene terephthalate (PET) fibers, nylon fibers and the like can be used. Further, these two or more kinds of fibers may be mixed to form a non-woven fabric.

The separator 23 may have a structure including a base material and a surface layer provided on one side or both sides of the base material. The surface layer contains inorganic particles having an electrically insulating property, and a resin material that binds the inorganic particles to the surface of the base material and also binds the inorganic particles to each other. This resin material may have, for example, a three-dimensional network structure in which fibrils are formed and a plurality of fibrils are connected. Inorganic particles are supported on a resin material having this three-dimensional network structure. Further, the resin material may bind the surface of the base material or the inorganic particles to each other without becoming fibril. In this case, higher binding properties can be obtained. By providing the surface layer on one side or both sides of the base material as described above, the oxidation resistance, heat resistance and mechanical strength of the separator 23 can be improved.

The base material is a porous membrane composed of an insulating membrane that allows lithium ions to permeate and has a predetermined mechanical strength. Since the electrolytic solution is held in the pores of the base material, it is resistant to the electrolytic solution. It is preferable that the properties are high, the reactivity is low, and the swelling is difficult.

As the material constituting the base material, the resin material or non-woven fabric constituting the above-mentioned separator can be used.

Inorganic particles include at least one such as metal oxides, metal nitrides, metal carbides and metal sulfides. Examples of metal oxides include aluminum oxide (alumina, Al ₂ O ₃ ), boehmite (alumina monohydrate), magnesium oxide (MgO), titanium oxide (TiO ₂ ), zirconium oxide (ZrO ₂ ), and silicon oxide (silica). , SiO ₂ ) or yttrium oxide (Y ₂ O ₃ ) or the like can be preferably used. As the metal nitride, silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), boron nitride (BN), titanium nitride (TiN) and the like can be preferably used. As the metal carbide, silicon carbide (SiC), boron carbide (B ₄ C) or the like can be preferably used. As the metal sulfide, barium sulfate (BaSO ₄ ) or the like can be preferably used. In addition, _{porous aluminosilicates such as zeolite (M 2 / n} O, Al ₂ O ₃ , xSiO ₂ , yH ₂ O, M is a metal element, x ≧ 2, y ≧ 0), layered silicate, and barium titanate. Minerals such as barium (BaTIO ₃ ) or strontium titanate (SrTiO ₃ ) may be used. The inorganic particles have oxidation resistance and heat resistance, and the surface layer on the side surface facing the positive electrode containing the inorganic particles has strong resistance to the oxidizing environment in the vicinity of the positive electrode during charging. The shape of the inorganic particles is not particularly limited, and any of spherical, plate-like, fibrous, cubic, random and the like can be used.

The particle size of the inorganic particles is preferably in the range of 1 nm or more and 10 μm or less. If the particle size is less than 1 nm, it is difficult to obtain inorganic particles. On the other hand, if the particle size exceeds 10 μm, the distance between the electrodes becomes large, the amount of active material filled cannot be sufficiently obtained in a limited space, and the battery capacity decreases.

Examples of the resin material constituting the surface layer include fluororesins such as polyvinylidene fluoride and polytetrafluoroethylene, fluororubber containing vinylidene fluoride-tetrafluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer and the like, and styrene. -Containant copolymers or hydrides thereof, polyamides such as total aromatic polyamide (aramid), acrylic acid resins or polyesters and the like, and resins having high heat resistance at least one of the melting point and the glass transition temperature of 180 ° C. or higher can be mentioned. .. These resin materials may be used alone or in combination of two or more. Among them, a fluorine-based resin such as polyvinylidene fluoride is preferable from the viewpoint of oxidation resistance and flexibility, and aramid or polyamide-imide is preferably contained from the viewpoint of heat resistance.

As a method for forming the surface layer, for example, a slurry composed of a matrix resin, a solvent and an inorganic substance is applied onto a base material (porous film), and the matrix resin is passed through a poor solvent and a parent solvent bath of the above solvent to form a phase. A method of separating and then drying can be used.

The above-mentioned inorganic particles may be contained in a porous membrane as a base material. Further, the surface layer may be composed of only a resin material without containing inorganic particles.

(Electrolytic solution)
The electrolytic solution contains an organic solvent (non-aqueous solvent) and an electrolyte salt dissolved in the organic solvent. Instead of the electrolytic solution, a gel-like electrolyte layer containing the electrolytic solution and a polymer compound serving as a retainer for holding the electrolytic solution may be used.

As the organic solvent, a cyclic carbonate ester such as ethylene carbonate or propylene carbonate can be used, and it is preferable to use one of ethylene carbonate and propylene carbonate, particularly both. This is because the cycle characteristics can be further improved. Further, in addition to these carbonic acid esters, it is preferable to use a mixed chain carbonate ester such as diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate or methyl propyl carbonate. This is because high ionic conductivity can be obtained.

The organic solvent preferably further contains vinylene carbonate. This is because the cycle characteristics can be further improved. In addition, a nitrile-based electrolytic solution (acetonitrile, succinonitrile, adiponitrile, etc.) can also be used.

Examples of the electrolyte salt include _{lithium salts such as LiPF 6 , LiBF 4} , LiAsF ₆ , LiClO ₄ , LiCl, lithium difluoro [oxorat-O, O≡] borate, and lithium bisoxalate volate.

[Battery operation]
In the battery having the above-described configuration, when charging is performed, for example, lithium ions are released from the positive electrode active material layer 21B and are occluded in the negative electrode active material layer 22B via the electrolytic solution. Further, when the electric discharge is performed, for example, lithium ions are released from the negative electrode active material layer 22B and are occluded in the positive electrode active material layer 21B via the electrolytic solution.

[Battery manufacturing method]
Next, an example of a method for manufacturing a battery according to an embodiment of the present invention will be described.
First, a positive electrode active material, a conductive agent, and a binder are mixed to prepare a positive electrode mixture, and this positive electrode mixture is dispersed in a solvent such as N-methyl-2-pyrrolidone (NMP) to form a paste-like positive electrode. Prepare a mixture slurry. Next, this positive electrode mixture slurry is applied to both sides of the positive electrode current collector 21A, the solvent is dried, and the positive electrode active material is applied to the positive electrode current collector 21A by compression molding with a roll press machine to activate the positive electrode. The material layer 21B is formed, and the positive electrode 21 is formed. At this time, by adjusting the coating position of the positive electrode mixture slurry, the positive electrode current collector exposed portion 21C is also formed on the positive electrode 21.

The negative electrode 22 can be manufactured in the same manner as the positive electrode 21. At this time, by adjusting the coating position of the negative electrode mixture slurry, the negative electrode current collector exposed portion 22C and the negative electrode current collector exposed portion 22D are formed on the negative electrode 22.

Next, the positive electrode lead 25 is attached to the positive electrode current collector exposed portion 21C by welding, and the negative electrode leads 26 and 27 are attached to the negative electrode current collector exposed portions 22C and 22D by welding. Further, the positive electrode bonding film material 28 is adhered in the plane of the positive electrode current collector exposed portion 21C to which the positive electrode lead 25 is attached. Next, the positive electrode 21 and the negative electrode 22 are laminated via the separator 23 to form an electrode laminate, and the electrode laminate is wound with one end in the longitudinal direction of the electrode laminate as the winding start end (the electrode laminate is wound. In the example of FIG. 5A, the negative electrode current collector exposed portion 22C side is used as the winding start end for winding). At this time, in the electrode laminate, the center position in the width direction of the positive electrode 21 (in the direction of the double arrow Y in FIG. 5A) is overlapped with the center position in the width direction of the negative electrode 22 (in the direction of the double arrow Y in FIG. 5). preferable. The electrode body 20 is formed by winding the electrode laminate. In the electrode body 20, one end side portion of the positive electrode lead 25 and one end side portion of the negative electrode leads 26 and 27 extend outward.

Next, the tip of the positive electrode lead 25 is welded to the safety valve mechanism 15, and the tips of the negative electrode lead 26 and the negative electrode lead 27 are welded to the battery can 11, and the wound electrode body having the positive electrode 21 and the negative electrode 22 wound. Is stored inside the battery can 11 in a state of being sandwiched between the pair of insulating plates 12 and 13. Next, the electrolytic solution is injected into the battery can 11 to impregnate the separator 23. Next, the battery lid 14, the safety valve mechanism 15, and the heat-sensitive resistance element 16 are fixed to the open end of the battery can 11 by being crimped via the sealing gasket 17. As a result, the battery shown in FIG. 1 is obtained. When the negative electrode bonding film materials 29 and 30 are provided at predetermined positions on the same surface as the surface on which the negative electrode leads 26 and 27 are attached to the negative electrode current collector exposed portion 22C and the negative electrode current collector exposed portion 22D. When the negative electrode leads 26 and 27 are attached to the negative electrode current collectors exposed portions 22C and 22D by welding or the like, the negative electrode bonding film materials 29 and 30 are the negative electrode current collector exposed portions 22C and the negative electrode current collector exposed portions 22D. Is glued to.

[effect]
As described above, in the battery according to the embodiment, the positive electrode lead 25 is bonded to the positive electrode current collector exposed portion 21C of the electrode body 20 with a predetermined length. As a result, when a force is applied from the outer peripheral surface of the battery toward the center near the center of the battery can 11 in the tubular axial direction to cause deformation of the electrode body 20, the positive electrode lead 25 becomes the positive electrode current collector 21A. It is possible to suppress the possibility that a large pressure is applied. Therefore, in the battery according to one embodiment, it is possible to prevent the electrode body 20 from being damaged by the positive electrode current collector 21A, the separator 23, and the like, and it is possible to prevent the positive electrode 21 and the negative electrode 22 from being short-circuited. Therefore, the impact resistance of the battery can be improved.

When the positive electrode lead is joined to the exposed portion of the positive electrode current collector of the electrode body, the exposed portion of the positive electrode current collector is bonded to the exposed portion of the positive electrode body, and the portion overlapping the positive electrode lead in the winding axis direction of the wound electrode body is larger than the other parts. The maximum thickness increases by the amount of the positive electrode lead provided, and a difference in thickness occurs in the electrode laminate in the winding axis direction of the wound electrode body. Then, depending on such a thickness difference, there is a possibility that winding misalignment may occur during the formation of the wound electrode body. In this respect, in the battery according to one embodiment, the positive electrode bonding film material 28 is provided at a position facing the inner end portion 25A of the positive electrode lead 25, so that the electrode laminate is provided in the winding axis direction of the wound electrode body. Since the thickness difference is set within a predetermined range, it is possible to suppress the possibility of winding misalignment during the formation of the electrode body 20.

Although the case where the first electrode is the positive electrode and the second electrode is the negative electrode has been described above, the first electrode may be the negative electrode and the second electrode may be the positive electrode. In that case, on the negative electrode, an exposed portion of the negative electrode current collector in which a part of the negative electrode current collector is not coated with the negative electrode active material is formed at the non-end portion of the negative electrode in the longitudinal direction of the first electrode. The negative electrode lead is joined to the exposed portion of the negative electrode current collector. Further, the length of the portion of the negative electrode lead facing either one or both of the separator and the positive electrode is shorter than the length of 50% of the width of the positive electrode. Then, the negative electrode bonding film material is provided in the region of the exposed portion of the negative electrode current collector where the negative electrode lead is not provided. Further, in this case, the length of the portion of the positive electrode lead that overlaps the exposed portion of the positive electrode current collector is preferably shorter than the length of 50% of the width of the positive electrode.

[Example 1]
The positive electrode and the negative electrode were manufactured as follows, and the battery was assembled.

(Cathode manufacturing process)
A positive electrode mixture was obtained by mixing 91 parts by mass of lithium nickel composite oxide (NCA) as a positive electrode active material, 6 parts by mass of graphite as a conductive agent, and 3 parts by mass of polyvinylidene fluoride as a binder, and then N-. By dispersing in methyl-2-pyrrolidone, a paste-like positive electrode mixture slurry was obtained. Next, a positive electrode mixture slurry was applied to both sides of a positive electrode current collector made of a strip-shaped aluminum foil (thickness of 15 μm), dried, and then compression-molded with a roll press to form a positive electrode active material layer. .. At this time, the positive electrode mixture slurry is formed so that the positive electrode current collector exposed portion is formed from one end to the other end in the width direction of the positive electrode on both sides of the central portion in the longitudinal direction of the positive electrode. The coating position and coating area were adjusted. Next, both ends in the longitudinal direction of the positive electrode were cut so that the positive electrode active material layer and the tips of the positive electrode current collector were aligned at both ends in the longitudinal direction of the positive electrode. Next, an aluminum positive electrode lead was attached to the exposed portion of the positive electrode current collector, which was planned to be located on the inner side surface side after winding, by ultrasonic welding. Next, the positive electrode bonding film material was attached to the exposed portion of the positive electrode current collector so as to face the end surface of the inner end portion of the positive electrode lead.

(Negative electrode manufacturing process)
97 parts by mass of artificial graphite powder as a negative electrode active material and 3 parts by mass of polyvinylidene fluoride as a binder are mixed to obtain a negative electrode mixture, which is then dispersed in N-methyl-2-pyrrolidone to form a paste-like negative electrode. A mixture slurry was obtained. Next, a negative electrode mixture slurry was applied to both sides of a negative electrode current collector made of a strip-shaped copper foil (15 μm thick), dried, and then compression-molded with a roll press to form a negative electrode active material layer. .. At this time, the negative electrode mixture slurry is formed so that the negative electrode current collector exposed portion is formed from one end to the other end in the width direction of the negative electrode on both both ends in the longitudinal direction of the negative electrode. The coating position and coating area were adjusted. Next, a nickel negative electrode lead was ultrasonically welded onto the exposed negative electrode current collector, which was planned to be located on the inner surface of the central end after winding. A nickel negative electrode lead was also attached to the exposed negative electrode current collector exposed portion, which was planned to be located on the inner surface of the outer peripheral end after winding, by ultrasonic welding.

(Battery assembly process)
The positive electrode and the negative electrode obtained through the above-mentioned positive electrode manufacturing step and the negative electrode manufacturing step are laminated in the order of the negative electrode, the separator, the positive electrode, and the separator via a separator made of a microporous polyethylene biaxially stretched film having a thickness of 10 μm. Obtained an electrode laminate. Next, a wound electrode body was obtained as a power generation element by starting winding from one end side of the negative electrode to which the negative electrode lead of the electrode laminate was attached and winding the electrode stack many times.

Next, the wound electrode body is sandwiched between a pair of insulating plates, the extending tips of the two negative electrode leads are welded to the battery can, and the extending tips of the positive electrode leads are welded to the safety valve mechanism to form the electrode body. It was stored inside the battery can. Next, a non-aqueous electrolyte solution was prepared by dissolving _{LiPF 6} as an electrolyte salt at a concentration of 1 mol / dm ³ in a solvent in which ethylene carbonate and methyl ethyl carbonate were mixed at a volume ratio of 1: 1.

Finally, after injecting the electrolytic solution into the battery can containing the above-mentioned electrode body, the safety valve, the PTC element and the battery lid are fixed by crimping the battery can through the insulating sealing gasket to fix the outer diameter. A cylindrical battery having a diameter of 18 mm and a height of 65 mm was obtained.

In the battery of Example 1, the width W1 of the positive electrode, the width W2 of the negative electrode, the length Wh2 of the portion of the positive electrode lead facing the negative electrode via the separator, and the length of the overlapping portion of the positive electrode lead and the exposed portion of the positive electrode current collector. Table 1 shows Wh1, the lengths Wz1 and Wz2 of the portion where the negative electrode lead and the exposed portion of the negative electrode current collector overlap. The length Wz1 is the length of the portion where the exposed negative electrode current collector and the negative electrode lead at the central end of the wound electrode body overlap, and the length Wz1 is the negative electrode at the outer peripheral end of the wound electrode body. This is the length of the portion where the exposed part of the current collector and the negative electrode lead overlap.

[Evaluation]
A collision test was performed on the battery of Example 1.

(Crash test)
A test according to the collision test specified in UL1642 regarding the safety test for lithium ion batteries was carried out, and the limit height (cm) at which ignition did not occur was measured. The results are shown in Table 1.

[Example 2, Comparative Example 1]
In Example 2 and Comparative Example 1, the width W1 of the positive electrode, the width W2 of the negative electrode, the length Wh2 of the portion of the positive electrode lead facing the negative electrode via the separator, and the overlapping portion of the positive electrode lead and the exposed portion of the positive electrode current collector. A battery was obtained in the same manner as in Example 1 except that the lengths Wh1 and the lengths Wz1 and Wz2 of the portion overlapping the negative electrode lead and the exposed portion of the negative electrode current collector are as shown in Table 1.

[Example 3]
The width W1 of the positive electrode, the width W2 of the negative electrode, the length Wh2 of the portion of the positive electrode lead facing the negative electrode via the separator, the length Wh1 of the overlapping portion of the positive electrode lead and the exposed portion of the positive electrode current collector, the negative electrode lead and the negative electrode collection. The lengths Wz1 and Wz2 of the portion overlapping with the exposed portion of the electric body are as shown in Table 1, and in the process of manufacturing the negative electrode, with respect to the exposed portion of the negative electrode current collector that is on the central end side of the negative electrode. A battery was obtained in the same manner as in Example 1 except that the negative electrode bonding film material was attached to the exposed portion of the negative electrode current collector so as to face the end surface of the inner end portion of the negative electrode lead.

For Examples 2 and 3 and Comparative Example 1, a collision test was carried out in the same manner as in Example 1. The results are shown in Table 1.

[Examples 4 and 5]
In Examples 4 and 5, batteries were prepared by the same steps as in Example 2. However, in Examples 4 and 5, the thickness (μm) of the positive electrode lead and the thickness (μm) of the positive electrode bonding film material were values as shown in Table 2.

[Comparative Example 2]
A battery was prepared in the same manner as in Example 4 except that the positive electrode bonding film material was not provided. The thickness of the positive electrode lead was a value as shown in Table 2.

For the batteries of Examples 4 and 5 and the battery of Comparative Example 2, the amount of electrode meandering of the wound electrode body incorporated in the battery was measured. The measurement of the electrode meandering amount was carried out as shown below.

[Evaluation]
(Measurement of electrode meandering amount)
When the electrode laminate is wound in the winding direction (winding direction P in the example of FIG. 5A) in order to form the wound electrode body, the electrode laminate is wound with the end position at which the winding start is started as a reference position. The maximum value of the amount of deviation indicating how much deviation (movement distance in the winding axis direction R in the example of FIG. 5A) occurs from the reference position in the winding axis direction by the end is measured as the electrode meandering amount (cm). did. For example, if the number of windings exceeds 11 from the beginning of winding and then the winding starts diagonally to cause a deviation, the deviation becomes maximum when the number of windings is 14 and then the deviation does not increase until the end of winding. The amount of deviation when the number of windings is 14 is the amount of electrode meandering. The results are shown in Table 2.

Comparing Examples 1 to 3 and Comparative Example 1 based on the results of the above-mentioned collision test, it was confirmed that Examples 1 to 3 can improve the impact resistance of the battery as compared with Comparative Example 1. It was.

Comparing Examples 4, 5 and Comparative Example 2 based on the results of the above-mentioned meandering amount measurement, it was confirmed that Examples 4 and 5 can suppress unwinding as compared with Comparative Example 2.

<Application example>
(1) Battery Pack FIG. 6 is a block diagram showing a circuit configuration example when the secondary battery according to the embodiment or embodiment of the present invention is applied to the battery pack 300. The battery pack 300 includes a switch unit 304 including an assembled battery 301, a charge control switch 302a, and a discharge control switch 303a, a current detection resistor 307, a temperature detection element 308, and a control unit 310. The control unit 310 can control each device, perform charge / discharge control when abnormal heat generation occurs, and calculate and correct the remaining capacity of the battery pack 300.

When charging the battery pack 300, the positive electrode terminal 321 and the negative electrode terminal 322 are connected to the positive electrode terminal and the negative electrode terminal of the charger, respectively, and charging is performed. Further, when the electronic device connected to the battery pack 300 is used, the positive electrode terminal 321 and the negative electrode terminal 322 are connected to the positive electrode terminal and the negative electrode terminal of the electronic device, respectively, and discharge is performed.

The assembled battery 301 is formed by connecting a plurality of secondary batteries 301a in series and / or in parallel. In FIG. 6, the case where the six secondary batteries 301a are connected in two parallels and three series (2P3S) is shown as an example, but any connection method may be used.

The temperature detection unit 318 is connected to a temperature detection element 308 (for example, a thermistor), measures the temperature of the assembled battery 301 or the battery pack 300, and supplies the measured temperature to the control unit 310. The voltage detection unit 311 measures the voltage of the assembled battery 301 and each of the secondary batteries 301a constituting the assembled battery 301, A / D converts the measured voltage, and supplies the measured voltage to the control unit 310. The current measuring unit 313 measures the current using the current detection resistor 307, and supplies the measured current to the control unit 310.

The switch control unit 314 controls the charge control switch 302a and the discharge control switch 303a of the switch unit 304 based on the voltage and current input from the voltage detection unit 311 and the current measurement unit 313. The switch control unit 314 controls the switch unit 304 to be OFF when any voltage of the secondary battery 301a becomes equal to or lower than the overcharge detection voltage or the overdischarge detection voltage, or when a large current suddenly flows. By sending a signal, overcharging, overdischarging, and overcurrent charging / discharging are prevented. Here, when the secondary battery is a lithium ion secondary battery, the overcharge detection voltage is determined to be, for example, 4.20 V ± 0.05 V, and the over discharge detection voltage is determined to be, for example, 2.4 V ± 0.1 V.

After the charge control switch 302a or the discharge control switch 303a is turned off, charging or discharging is possible only through the diode 302b or the diode 303b. As these charge / discharge switches, semiconductor switches such as MOSFETs can be used. In this case, the parasitic diodes of the MOSFET function as diodes 302b and 303b. Although the switch portion 304 is provided on the + side in FIG. 6, it may be provided on the − side.

The memory 317 is composed of a RAM or a ROM, and includes, for example, an EPROM (Erasable Programmable Read Only Memory) which is a non-volatile memory. The memory 317 stores in advance the numerical values calculated by the control unit 310, the battery characteristics in the initial state of each secondary battery 301a measured at the stage of the manufacturing process, and the like, and can be rewritten as appropriate. Further, by storing the fully charged capacity of the secondary battery 301a, the remaining capacity can be calculated in cooperation with the control unit 310.

(2) Electronic device The secondary battery according to the embodiment or embodiment of the present invention described above can be mounted on a device such as an electronic device, an electric transport device, or a power storage device and used to supply electric power.

Electronic devices include, for example, laptop computers, smartphones, tablet terminals, PDAs (personal digital assistants), mobile phones, wearable terminals, video movies, digital still cameras, electronic books, music players, headphones, game machines, pacemakers, hearing aids, etc. Examples include power tools, televisions, lighting equipment, toys, medical equipment, and robots. In a broad sense, electronic devices may also include electric transport devices, power storage devices, power tools, and electric unmanned aerial vehicles, which will be described later.

Examples of electric transportation equipment include electric vehicles (including hybrid vehicles), electric motorcycles, electrically assisted bicycles, electric buses, electric carts, unmanned transport vehicles (AGV), railway vehicles, and the like. It also includes electric passenger aircraft and electric unmanned aerial vehicles for transportation. The secondary battery according to the present invention is used not only as a power source for driving these, but also as an auxiliary power source, a power source for energy regeneration, and the like.

Examples of the power storage device include a power storage module for commercial or household use, a power storage power source for a building such as a house, a building, an office, or a power generation facility.

(3) Power Tool With reference to FIG. 7, an example of an electric screwdriver as an electric tool to which the present invention can be applied will be schematically described. The electric screwdriver 431 is provided with a motor 433 that transmits rotational power to the shaft 434 and a trigger switch 432 that is operated by the user. By operating the trigger switch 432, a screw or the like is driven into the object by the shaft 434.

The battery pack 430 and the motor control unit 435 are housed in the lower housing of the handle of the electric screwdriver 431. As the battery pack 430, the battery pack 300 described above can be used. The battery pack 430 is built into the electric screwdriver 431 or is detachable. The battery pack 430 can be attached to the charging device in a state of being built in or removed from the electric driver 431.

Each of the battery pack 430 and the motor control unit 435 is equipped with a microcomputer. Power is supplied from the battery pack 430 to the motor control unit 435, and charge / discharge information of the battery pack 430 is communicated between both microcomputers. The motor control unit 435 can control the rotation / stop and the rotation direction of the motor 433, and can cut off the power supply to the load (motor 433 and the like) at the time of over-discharging.

(4) Power Storage System for Electric Vehicles As an example of applying the present invention to a power storage system for electric vehicles, FIG. 8 schematically shows a configuration example of a hybrid vehicle (HV) adopting a series hybrid system. The series hybrid system is a vehicle that runs on a power driving force converter using the electric power generated by an engine-powered generator or the electric power temporarily stored in a battery.

The hybrid vehicle 600 includes an engine 601, a generator 602, a power driving force converter 603 (DC motor or AC motor; hereinafter simply referred to as "motor 603"), drive wheels 604a, drive wheels 604b, wheels 605a, and wheels 605b. , Battery 608, vehicle control device 609, various sensors 610, and charging port 611 are mounted. The battery pack 300 of the present invention described above or a power storage module equipped with a plurality of secondary batteries of the present invention can be applied to the battery 608. The shape of the secondary battery is cylindrical, square or laminated.

The motor 603 is operated by the electric power of the battery 608, and the rotational force of the motor 603 is transmitted to the drive wheels 604a and 604b. The rotational force of the engine 601 is transmitted to the generator 602, and the electric power generated by the generator 602 by the rotational force can be stored in the battery 608. The various sensors 610 control the engine speed and the opening degree of a throttle valve (not shown) via the vehicle control device 609. The various sensors 610 include a speed sensor, an acceleration sensor, an engine speed sensor, and the like.

When the hybrid vehicle 600 is decelerated by a braking mechanism (not shown), the resistance force at the time of deceleration is applied to the motor 603 as a rotational force, and the regenerative power generated by this rotational force is stored in the battery 608. Further, although not shown, an information processing device (for example, a battery remaining amount display device) that performs information processing related to vehicle control based on information on the secondary battery may be provided. The battery 608 can receive electric power and store electricity by being connected to an external power source via the charging port 611 of the hybrid vehicle 600. Such an HV vehicle is called a plug-in hybrid vehicle (PHV or PHEV).

In the above, the series hybrid vehicle has been described as an example, but the present invention can also be applied to a parallel system in which an engine and a motor are used together, or a hybrid vehicle in which a series system and a parallel system are combined. Furthermore, the present invention is also applicable to an electric vehicle (EV or BEV) or a fuel cell vehicle (FCV) that travels only with a drive motor that does not use an engine.

<Modification example>
Although the embodiments and examples of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments and examples, and various modifications based on the technical idea of the present invention are possible. Is.

For example, the configurations, methods, processes, shapes, materials, numerical values, etc. given in the above-described embodiments and examples are merely examples, and if necessary, different configurations, methods, processes, shapes, materials, numerical values, etc. May be used. In addition, the configurations, methods, processes, shapes, materials, numerical values, and the like of the above-described embodiments and examples can be combined with each other as long as they do not deviate from the gist of the present invention.

The chemical formulas of the compounds exemplified in the above-described embodiments are typical, and the general names of the same compounds are not limited to the stated valences and the like. In the numerical range described stepwise in the above embodiment, the upper limit value or the lower limit value of the numerical range of one step may be replaced with the upper limit value or the lower limit value of the numerical range of another step. Unless otherwise specified, the materials exemplified in the above-described embodiments may be used alone or in combination of two or more.

11 ... Battery cans 12, 13 ... Insulation plate 14 ... Battery lid 15 ... Safety valve mechanism 15A ... Disc plate 16 ... Heat-sensitive resistance element 17 ... Gasket 20 ... Winding Circular electrode body 21 ... Positive electrode 21A ... Positive electrode current collector 21B ... Positive electrode active material layer 21C ... Positive electrode current collector Exposed part 21S ... Main surface 22 ... Negative electrode 22A ... Negative electrode current collector 22B ... Negative electrode active material layer 22C, 22D ... Negative electrode current collector exposed part 22S ... Main surface 23 ... Separator 25 ... Positive electrode lead 25A ... Inner end of positive electrode lead Part 25B ... Outer end of the positive electrode lead facing the negative electrode 26, 27 ... Negative electrode lead 26A, 27A ... Inner end of the negative electrode lead 28 ... Positive electrode bonding film material 29, 30.・ ・ Negative electrode bonding film material

Claims (11)

1. Winding electrode body and
   It is equipped with an outer can for accommodating the wound electrode body.
   The wound electrode body includes a band-shaped first electrode having a first lead and a first adhesive film material, a band-shaped second electrode, and the first electrode and the second electrode. It has a structure in which a strip-shaped separator provided between them is wound in the longitudinal direction.
   The first electrode has a first current collector exposed portion to which the first active material layer is not provided between both ends in the longitudinal direction of the first electrode.
   The first lead is provided on the exposed portion of the first current collector so that one end side projects from the long side side of the first electrode.
   The length of the portion of the first lead facing either one or both of the separator and the second electrode is shorter than 50% of the width of the second electrode.
   The first adhesive film material is a battery provided in a region of the first exposed part of the current collector where the first lead is not provided.
2. The second electrode has a second reed and a second adhesive film material.
   The second electrode has a second current collector exposed portion on which the second active material layer is not provided at both ends or one end in the longitudinal direction of the second electrode.
   The second lead is provided on the exposed portion of the second current collector so that one end side projects from the long side side of the second electrode.
   The length of the portion of the second lead that overlaps the exposed portion of the second current collector is shorter than the length of 50% of the width of the second electrode.
   The battery according to claim 1, wherein the second adhesive film material is provided in a region of the exposed portion of the second current collector where the second lead is not provided.
3. The first electrode, the first lead, the first adhesive film material, the first active material layer, and the first current collector exposed portion are a positive electrode, a positive electrode lead, and a positive electrode, respectively. Corresponds to the adhesive film material, the positive electrode active material layer, and the exposed part of the positive electrode current collector,
   The second electrode, the second lead, the second adhesive film material, the second active material layer, and the second current collector exposed portion are a negative electrode, a negative electrode lead, and a negative electrode, respectively. The battery according to claim 2, which corresponds to the adhesive film material, the negative electrode active material layer, and the exposed portion of the negative electrode current collector.
4. The battery according to claim 3, wherein the length of the portion of the positive electrode lead that overlaps the exposed portion of the positive electrode current collector is 10% or more of the width of the positive electrode.
5. The battery according to claim 3 or 4, wherein the length of the portion of the positive electrode lead facing either one or both of the separator and the negative electrode is 45% or less of the width of the negative electrode.
6. The battery according to any one of claims 3 to 5, wherein the thickness of the positive electrode bonding film material is within the range of 20% or more and 120% or less of the thickness of the positive electrode lead.
7. The battery according to any one of claims 3 to 6, wherein the length of the portion of the negative electrode lead that overlaps the negative electrode current collector is 10% or more and 45% or less of the width of the negative electrode.
8. The battery according to any one of claims 3 to 7, wherein the thickness of the negative electrode adhesive film material is within the range of 20% or more and 120% or less of the thickness of the negative electrode lead.
9. The battery according to any one of claims 3 to 8, wherein at least one of the positive electrode bonding film material and the negative electrode bonding film material is composed of a film material having a base material and an adhesive layer.
10. An electronic device having the battery according to any one of claims 1 to 9.
11. A power tool having a battery according to any one of claims 1 to 9.

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