Patent Description:
Conventionally, a battery including a winding electrode body in which a strip-shaped positive electrode including a positive electrode active material layer on a positive electrode collector and a strip-shaped negative electrode including a negative electrode active material layer on a negative electrode collector are laminated with each other via a strip-shaped separator and wound about a winding axis has been known (see <CIT>). For example, <CIT> discloses a winding electrode body in which a plurality of tabs (lead withdrawing parts) that are a part of a positive electrode collector protrude from one end in a winding axis direction and a plurality of tabs that are a part of a negative electrode collector protrude from the other end. In the Patent Literature, the outside surface of the winding electrode body is covered with a separator. The plurality of tabs are bundled together as one and welded and joined to a lead for current collection.

Further, patent document <CIT> discloses a rechargeable battery comprising an electrode assembly, a case accommodating the electrode assembly, and a retainer in the case and surrounding the electrode assembly. The retainer includes a first retainer surrounding one portion of the electrode assembly, a second retainer surrounding another portion of the electrode assembly, and a connecting portion connecting the first retainer and the second retainer.

Patent document <CIT> discloses a lithium secondary battery, in which a flat-shaped panel is arranged inside a flexible case, so that the amount of an electrolyte introduced into the flexible case can be increased, that in addition, an amount of the electrolyte lost or dispersed in an exhaust process of the flexible case etc. can be decreased, and that the lithium secondary battery with an improved structural stiffness is achieved. The lithium secondary battery comprises: a plurality of flat-shaped electrode assemblies including a first electrode, a second electrode and a separation membrane; the flexible case that accommodates the plurality of flat-shaped electrode assemblies; and the flat-shaped panel that is accommodated inside of the flexible case and located between the electrode assemblies.

Moreover, patent document <CIT> discloses a battery cell having an electrode assembly mounted in a variable cell case in a state in which the electrode assembly is impregnated with an electrolyte, the battery cell being configured to be flexibly deformed in response to the shape of a device, in which the battery cell is mounted, wherein a coating part including inert particles is formed on at least one outer surface of the electrode assembly.

According to studies by the present inventors, a plurality of tabs have play so as to be movable in a direction crossing a direction protruding from a collector. Therefore, if vibration, shock, or the like is applied from an outside during the use of a battery or the like, a winding electrode body may contact a battery case or a component attached to the battery case. As a result, there is a possibility that a separator covering the outside surface of the winding electrode body is damaged and a positive electrode and a negative electrode are short-circuited to each other.

The present teaching has been made in view of the above circumstances and has an object of providing a battery that prevents the short circuit between a positive electrode and a negative electrode and improves reliability and a manufacturing method for the battery.

The above object is solved by the subject-matters according to the independent claims. Further advantageous configurations of the invention can be drawn from the dependent claims.

According to the present teaching, there is provided a battery including: an exterior body having a bottom wall, a pair of first side walls extending from the bottom wall and facing each other, a pair of second side walls extending from the bottom wall and facing each other, and an opening facing the bottom wall; a sealing plate that seals the opening of the exterior body; at least one winding electrode body in which a strip-shaped positive electrode and a strip-shaped negative electrode are laminated with each other via a strip-shaped separator and wound about a winding axis; a positive electrode tab group that includes a plurality of positive electrode tabs provided at an end in a winding axis direction of the winding electrode body and is electrically connected to the positive electrode; and a negative electrode tab group that includes a plurality of negative electrode tabs provided at an end in the winding axis direction of the winding electrode body and is electrically connected to the negative electrode. The winding electrode body has a flat shape having a pair of curvature parts having a curved outside surface and a flat part that connects the pair of curvature parts to each other and has a flat outside surface and is accommodated in the exterior body so that one of the curvature parts faces the sealing plate and the other thereof faces the bottom wall of the exterior body. Wherein, when a line perpendicular to the winding axis of the winding electrode body and perpendicular to the bottom wall is assumed as L1, a portion positioned at an outermost periphery of the negative electrode in at least one of the pair of the curvature parts faces a portion positioned on a winding inner peripheral side of the negative electrode via the separator and not via the positive electrode on the line L1.

The winding electrode body of the battery is accommodated in the exterior body so that the curvature parts face the bottom wall of the exterior body and/or the sealing plate, and the portion positioned at the outermost periphery of the negative electrode in the curvature parts facing the bottom wall of the exterior body and/or the sealing plate faces the portion positioned on the winding inner peripheral side not via the positive electrode on the line L1. Thus, even if the curvature parts contact the bottom wall and/or the sealing plate and components provided in the bottom wall and the sealing plate to cause damage on the separator, it is possible to prevent the short circuit between the portion positioned at the outermost periphery of the negative electrode and the positive electrode. Accordingly, it is possible to improve the reliability of the battery.

In a preferred mode of the battery disclosed here, the battery includes a spacer arranged between the sealing plate and the winding electrode body, and the portion positioned at the outermost periphery of the negative electrode faces the portion positioned on the winding inner peripheral side of the negative electrode via the separator and not via the positive electrode on the line L1. With such a configuration, the winding electrode body is not liable to move greatly toward the sealing plate. Therefore, it is possible to prevent damage on the separator caused when the winding electrode body contacts the sealing plate. Thus, it is possible to effectively prevent the short circuit between the positive electrode and the negative electrode. Further, it is possible to reduce loads on the positive electrode tab group and/or the negative electrode tab group and stably maintain electrical connection. Thus, it is possible to improve the conduction reliability of the battery.

In a preferred mode of the battery disclosed here, the battery includes: a terminal that is attached to the sealing plate and electrically connected to the positive electrode tab group or the negative electrode tab group; a collecting part that electrically connects the positive electrode tab group or the negative electrode tab group and the terminal to each other; and an insulating member that insulates the sealing plate and the collecting part from each other and has a protrusion part protruding to a side of the winding electrode body from a side of the sealing plate, and the protrusion part of the insulating member constitutes the spacer. With such a configuration, it is possible to relax stress applied to the curvature parts even if the curvature parts contact the bottom wall and/or the sealing plate. Thus, the separator is not liable to be damaged, which makes it possible to effectively prevent the short circuit between the positive electrode and the negative electrode.

In a preferred mode of the battery disclosed here, the spacer does not contact the winding electrode body. Thus, when the spacer is arranged at a position separated from the electrode body, it is possible to prevent the curvature parts and the spacer from rubbing against each other even if the winding electrode body moves toward the sealing plate. Thus, the separator is not liable to be damaged, which makes it possible to effectively prevent the short circuit between the positive electrode and the negative electrode.

In a preferred mode of the battery disclosed here, the at least one winding electrode body includes a plurality of winding electrode bodies. In a battery including a plurality of winding electrode bodies, it is especially demanded that the short circuit between a positive electrode and a negative electrode be prevented to increase reliability. Accordingly, the application of the technology disclosed here is particularly effective.

In a preferred mode of the battery disclosed here, the separator includes a resinous base material part and a heat resistance layer that is provided on the base material part and contains an inorganic filler, and the outside surface of the winding electrode body is covered with the heat resistance layer in at least one of the pair of curvature parts. With such a configuration, it is possible to relax stress applied to the curvature parts even if the curvature parts contact the bottom wall and/or the sealing plate. Thus, the separator is not liable to be damaged, which makes it possible to effectively prevent the short circuit between the positive electrode and the negative electrode.

Further, according to the present teaching, there is provided a manufacturing method for a battery including an exterior body having a bottom wall, a pair of first side walls extending from the bottom wall and facing each other, a pair of second side walls extending from the bottom wall and facing each other, and an opening facing the bottom wall, a sealing plate that seals the opening of the exterior body, at least one winding electrode body in which a strip-shaped positive electrode and a strip-shaped negative electrode are laminated with each other via a strip-shaped separator and wound about a winding axis, a positive electrode tab group that includes a plurality of positive electrode tabs provided at an end in a winding axis direction of the winding electrode body and is electrically connected to the positive electrode, a negative electrode tab group that includes a plurality of negative electrode tabs provided at an end in the winding axis direction of the winding electrode body and is electrically connected to the negative electrode, and a spacer arranged between the sealing plate and the winding electrode body, the winding electrode body having a flat shape having a pair of curvature parts having a curved outside surface and a flat part that connects the pair of curvature parts to each other and has a flat outside surface and being accommodated in the exterior body so that one of the curvature parts faces the sealing plate and the other thereof faces the bottom wall of the exterior body. The manufacturing method includes: an insertion step of thrusting the winding electrode body into the exterior body with the spacer; and a sealing step of sealing the opening of the exterior body with the sealing plate. In the insertion step, a portion positioned at an outermost periphery of the negative electrode in at least a part of a region pressed by the spacer in the winding electrode body faces a portion positioned on a winding inner peripheral side of the negative electrode via the separator and not via the positive electrode.

In the manufacturing method, the winding electrode body is thrusted into the exterior body when the curvature parts of the winding electrode body are pressed by the spacer. At this time, the portion positioned at the outermost periphery of the negative electrode is caused to face the portion positioned on the winding inner peripheral side of the negative electrode via the separator and not via the positive electrode, which makes it possible to prevent the short circuit between the portion positioned at the outermost periphery of the negative electrode and the positive electrode even if the curvature parts are strongly pressed by the spacer. Further, the winding electrode body is caused to contact the sealing plate or a component attached to the sealing plate by the spacer, which makes it possible to prevent damage on the separator. Accordingly, it is possible to stably insert the winding electrode body into the exterior body and manufacture the battery.

When a line perpendicular to the winding axis of the winding electrode body and perpendicular to the bottom wall is assumed as L1, at least an outside surface positioned on the line L1 in the winding electrode body is pressed in the insertion step. Thus, it is possible to stably insert the winding electrode body into the exterior body, while preventing damage on the separator.

In a preferred mode of the manufacturing method disclosed here, the spacer does not contact the winding electrode body after the sealing step. Thus, it is possible to prevent damage on the separator caused when the curvature parts and the spacer rub against each other even if the winding electrode body moves toward the sealing plate.

In a preferred mode of the manufacturing method disclosed here, a shortest distance between the winding electrode body and the spacer is <NUM> or less after the sealing step. Thus, it is possible to make the electrode body and the spacer contact each other more suitably when thrusting the electrode body and more stably insert the electrode body into the exterior body.

Hereinafter, some preferred embodiments of a technology disclosed here will be described with reference to the drawings. Note that matters other than those mentioned particularly in the present specification and necessary for the implementation of the present invention (for example, a general configuration and a manufacturing process of a battery not characterizing the present invention) can be grasped as design matters for skilled persons based on conventional technologies in the field concerned. The technology disclosed here may be implemented on the basis of contents disclosed in the present specification and technological common knowledge in the field concerned.

In the present specification, a "battery" is a term indicating a general storage device from which electric energy is capable of being taken out and is a concept including a primary battery and a secondary battery. Further, in the present specification, a "secondary battery" is a term indicating a general storage device capable of performing repetitive charge and discharge and is a concept including a so-called storage battery (chemical cell) such as a lithium-ion secondary battery and a nickel hydrogen battery and a capacitor (physical cell) such as an electric double layer capacitor.

<FIG> is a perspective view of a battery <NUM>. <FIG> is a schematic longitudinal cross-sectional view taken along the line II-II in <FIG>. <FIG> is a schematic longitudinal cross-sectional view taken along the line III-III in <FIG>. <FIG> is a schematic transverse cross-sectional view taken along the line IV-IV in <FIG>. Note that in the following description, symbols L, R, F, Rr, U, and D in the drawings show a left side, a right side, a front side, a rear side, an upper side, and a lower side, respectively. Further, symbols X, Y, and Z in the drawings show a short side direction of the battery <NUM>, a long side direction orthogonal to the short side direction, and a vertical direction, respectively. The long side direction is an example of a winding axis direction. However, these directions show directions only for the convenience of explanation and do not intend to limit the installation mode of the battery <NUM> at all.

As shown in <FIG>, the battery <NUM> includes a battery case <NUM>, an electrode body group <NUM>, a positive electrode terminal <NUM>, a negative electrode terminal <NUM>, a positive electrode collecting part <NUM>, a negative electrode collecting part <NUM>, a positive electrode insulating member <NUM>, and a negative electrode insulating member <NUM>. As will be described in detail later, the electrode body group <NUM> has winding electrode bodies 20a, 20b, and 20c (see <FIG>). The positive electrode insulating member <NUM> has a base part 70a and a plurality of protrusion parts 70b. The negative electrode insulating member <NUM> has a base part 80a and a plurality of protrusion parts 80b. The protrusion parts 70b of the positive electrode insulating member <NUM> and the protrusion parts 80b of the negative electrode insulating member <NUM> are an example of spacers arranged between a sealing plate <NUM> and the winding electrode bodies 20a, 20b, and 20c. Although omitted in the figures, the battery <NUM> further includes an electrolytic solution here. The battery <NUM> is a lithium-ion secondary battery here. The battery <NUM> is characterized by including the winding electrode bodies 20a, 20b, and 20c, and the other configurations may be the same as those of conventional technologies.

The battery case <NUM> is a housing that accommodates the electrode body group <NUM>. The battery case <NUM> has a flat and bottomed cuboid (square) outer shape. The material of the battery case <NUM> may be the same as a conventionally-used one and is not particularly limited. The battery case <NUM> is preferably made of metal and more preferably made of, for example, aluminum, an aluminum alloy, iron, an iron alloy, or the like. As shown in <FIG>, the battery case <NUM> includes an exterior body <NUM> having an opening <NUM> and the sealing plate (lid body) <NUM> that seals the opening <NUM>.

As shown in <FIG>, the exterior body <NUM> includes a bottom wall 12a, a pair of long side walls 12b extending from the bottom wall 12a and facing each other, and a pair of short side walls 12c extending from the bottom wall 12a and facing each other. The bottom wall 12a has a substantially rectangular shape. The bottom wall 12a faces the opening <NUM>. The areas of the short side walls 12c are smaller than those of the long side walls 12b. The long side walls 12b and the short side walls 12c are an example of first side walls and second side walls disclosed here. The sealing plate <NUM> is attached so as to seal the opening <NUM> of the exterior body <NUM>. The sealing plate <NUM> faces the bottom wall 12a of the exterior body <NUM>. The sealing plate <NUM> has a substantially rectangular shape in a plan view. The battery case <NUM> is integrated in such a manner that the sealing plate <NUM> is joined (for example, welding joint) to the peripheral edge of the opening <NUM> of the exterior body <NUM>. The battery case <NUM> is air-tightly sealed.

As shown in <FIG>, the sealing plate <NUM> is provided with a solution injection hole <NUM>, a gas discharging valve <NUM>, and two terminal withdrawing holes <NUM> and <NUM>. The solution injection hole <NUM> is used to inject an electrolytic solution after the sealing plate <NUM> is attached to the exterior body <NUM>. The solution injection hole <NUM> is sealed by the sealing member <NUM>. The gas discharging valve <NUM> is configured to break and discharge gas inside the battery case <NUM> to an outside when the pressure inside the battery case <NUM> becomes a prescribed value or more. The terminal withdrawing holes <NUM> and <NUM> are formed at both ends in a long side direction Y of the sealing plate <NUM>, respectively. The terminal withdrawing holes <NUM> and <NUM> penetrate the sealing plate <NUM> in the vertical direction Z. The terminal withdrawing holes <NUM> and <NUM> have respective inside diameters of a size at which the positive electrode terminal <NUM> and the negative electrode terminal <NUM> before being attached to the sealing plate <NUM> (before caulking work) are insertable.

Each of the positive electrode terminal <NUM> and the negative electrode terminal <NUM> is fixed to the sealing plate <NUM>. The positive electrode terminal <NUM> is arranged on one side (the left side in <FIG> and <FIG>) in the long side direction Y of the sealing plate <NUM>. The negative electrode terminal <NUM> is arranged on the other side (the right side in <FIG> and <FIG>) in the long side direction Y of the sealing plate <NUM>. As shown in <FIG>, the positive electrode terminal <NUM> and the negative electrode terminal <NUM> are exposed to the outside surface of the sealing plate <NUM>. As shown in <FIG>, the positive electrode terminal <NUM> and the negative electrode terminal <NUM> are inserted into the terminal withdrawing holes <NUM> and <NUM>, respectively, and extend from the inside to the outside of the sealing plate <NUM>. Here, the positive electrode terminal <NUM> and the negative electrode terminal <NUM> are caulked by caulking work at peripheral edge portions surrounding the terminal withdrawing holes <NUM> and <NUM> of the sealing plate <NUM>. Caulking parts 30c and 40c are formed at ends (lower ends in <FIG>) on the side of the exterior body <NUM> of the positive electrode terminal <NUM> and the negative electrode terminal <NUM>.

As shown in <FIG>, the positive electrode terminal <NUM> is electrically connected to a positive electrode <NUM> (see <FIG>) of the electrode body group <NUM> via the positive electrode collecting part <NUM> inside the exterior body <NUM>. The negative electrode terminal <NUM> is electrically connected to a negative electrode <NUM> (see <FIG>) of the electrode body group <NUM> via the negative electrode collecting part <NUM> inside the exterior body <NUM>. The positive electrode terminal <NUM> is insulated from the sealing plate <NUM> by the positive electrode insulating member <NUM> and a gasket <NUM>. The negative electrode terminal <NUM> is insulated from the sealing plate <NUM> by the negative electrode insulating member <NUM> and a gasket <NUM>. The positive electrode terminal <NUM> and the negative electrode terminal <NUM> are an example of terminals disclosed here.

The positive electrode terminal <NUM> is preferably made of metal and more preferably made of, for example, aluminum or an aluminum alloy. The negative electrode terminal <NUM> is preferably made of metal and more preferably made of, for example, copper or a copper alloy. The negative electrode terminal <NUM> may be configured in such a manner that two conductive members are joined to and integrated with each other. For example, a portion connected to the negative electrode collecting part <NUM> may be made of copper or a copper alloy, and a portion exposed to the outside surface of the sealing plate <NUM> may be made of aluminum or an aluminum alloy.

As shown in <FIG>, a plate-shaped positive electrode outside conductive member <NUM> and a plate-shaped negative electrode outside conductive member <NUM> are attached to the outside surface of the sealing plate <NUM>. The positive electrode outside conductive member <NUM> is electrically connected to the positive electrode terminal <NUM>. The negative electrode outside conductive member <NUM> is electrically connected to the negative electrode terminal <NUM>. The positive electrode outside conductive member <NUM> and the negative electrode outside conductive member <NUM> are members to which a bus bar is annexed when a plurality of batteries <NUM> are electrically connected to each other. The positive electrode outside conductive member <NUM> and the negative electrode outside conductive member <NUM> are preferably made of metal and more preferably made of, for example, aluminum or an aluminum alloy. The positive electrode outside conductive member <NUM> and the negative electrode outside conductive member <NUM> are insulated from the sealing plate <NUM> by outside insulating members <NUM>. However, the positive electrode outside conductive member <NUM> and the negative electrode outside conductive member <NUM> are not necessarily provided and may be omitted in other embodiments.

<FIG> is a perspective view schematically showing the electrode body group <NUM> attached to the sealing plate <NUM>. Here, the electrode body group <NUM> has the three winding electrode bodies 20a, 20b, and 20c. However, the number of winding electrode bodies arranged inside the one exterior body <NUM> is not particularly limited and may be two or more (plural number) or one. The electrode body group <NUM> is arranged inside the exterior body <NUM> in a state of being covered with an electrode body holder <NUM> (see <FIG>) made of a resinous sheet.

<FIG> is a perspective view schematically showing the winding electrode body 20a. The winding electrode body 20a is arranged inside the exterior body <NUM> with its winding axis WL directed parallel to the long side direction Y. In other words, the winding electrode body 20a is arranged inside the exterior body <NUM> with the winding axis WL directed parallel to the bottom wall 12a and orthogonal to the short side walls 12c. The end surfaces of the winding electrode body 20a (in other words, laminated surfaces where the positive electrode <NUM> and the negative electrode <NUM> are laminated with each other, end surfaces in the long side direction Y in <FIG>) face the short side walls 12c.

<FIG> is a schematic view showing the configuration of the winding electrode body 20a. The winding electrode body 20a has the positive electrode <NUM>, the negative electrode <NUM>, and a separator <NUM>. Here, the winding electrode body 20a is configured in such a manner that the strip-shaped positive electrode <NUM> and the strip-shaped negative electrode <NUM> are laminated with each other via the strip-shaped separator <NUM> and wound about the winding axis WL. The winding electrode body 20a has a flat shape.

As shown in <FIG>, the positive electrode <NUM> has a positive electrode collector 22c and a positive electrode active material layer 22a and a positive electrode protection layer 22p that are fixed onto at least one surface of the positive electrode collector 22c. However, the positive electrode protection layer 22p is not necessarily provided and may be omitted in other embodiments. The positive electrode collector 22c has a strip shape. The positive electrode collector 22c is made of, for example, conductive metal such as aluminum, an aluminum alloy, nickel, and stainless steel. Here, the positive electrode collector 22c is metal foil and specifically aluminum foil.

At one end (the left end in <FIG>) in the long side direction Y of the positive electrode collector 22c, a plurality of positive electrode tabs 22t are provided. The plurality of positive electrode tabs 22t protrude toward one side (the left side in <FIG>) in the long side direction Y. The plurality of positive electrode tabs 22t protrude farther in the long side direction Y than the separator <NUM>. The plurality of positive electrode tabs 22t are (intermittently) provided at intervals along the longitudinal direction of the positive electrode <NUM>. Here, the positive electrode tabs 22t are a part of the positive electrode collector 22c and made of metal foil (aluminum foil). Here, each of the positive electrode tabs 22t has a trapezoidal shape. The positive electrode tabs 22t are portions (collector exposing parts) at which the positive electrode active material layer 22a and the positive electrode protection layer 22p of the positive electrode collector 22c are not formed. However, the positive electrode tabs 22t may be members different from the positive electrode collector 22c. Further, the positive electrode tabs 22t may be provided at the other end (the right end in <FIG>) in the long side direction Y, or may be provided at both respective ends in the long side direction Y.

As shown in <FIG>, the plurality of positive electrode tabs 22t are laminated with each other at the one end (the left end in <FIG>) in the long side direction Y and constitute a positive electrode tab group <NUM>. The plurality of positive electrode tabs 22t are folded and curved so as to make their outward-side ends aligned with each other. The positive electrode tab group <NUM> is electrically connected to the positive electrode terminal <NUM> via the positive electrode collecting part <NUM>. The plurality of positive electrode tabs 22t are preferably folded and electrically connected to the positive electrode terminal <NUM>. A positive electrode second collecting part <NUM> that will be described later is annexed to the positive electrode tab group <NUM>. The sizes (a length in the long side direction Y and a width orthogonal to the long side direction Y, see <FIG>) of the plurality of positive electrode tabs 22t may be appropriately adjusted according to, for example, their forming positions or the like in consideration of a state in which the plurality of positive electrode tabs 22t are connected to the positive electrode collecting part <NUM>. Here, the sizes of the plurality of positive electrode tabs 22t are different from each other so that the outward-side ends are aligned with each other when curved.

As shown in <FIG>, the positive electrode active material layer 22a is provided in a strip shape along the longitudinal direction of the strip-shaped positive electrode collector 22c. The positive electrode active material layer 22a contains a positive electrode active material (for example, a lithium transition metal composite oxide such as a lithium-nickel-cobalt-manganese composite oxide) capable of reversibly occluding and releasing a charge carrier. When the entire solid content of the positive electrode active material layer 22a is <NUM> mass%, the positive electrode active material may generally account for <NUM> mass% or more, typically account for <NUM> mass% or more, and account for, for example, <NUM> mass% or more. The positive electrode active material layer 22a may contain an arbitrary component other than the positive electrode active material, such as a conductive material, a binder, and various additive components. As the conductive material, a carbon material such as acetylene black (AB) can be, for example, used. As the binder, polyvinylidene fluoride (PVdF) can be, for example, used.

As shown in <FIG>, the positive electrode protection layer 22p is provided at the boundary portion between the positive electrode collector 22c and the positive electrode active material layer 22a in the long side direction Y. Here, the positive electrode protection layer 22p is provided at the one end (the left end in <FIG>) in the long side direction Y of the positive electrode collector 22c. However, the positive electrode protection layer 22p may be provided at both ends in the long side direction Y. The positive electrode protection layer 22p is provided in a strip shape along the positive electrode active material layer 22a. The positive electrode protection layer 22p contains an inorganic filler (for example, alumina). When the entire solid content of the positive electrode protection layer 22p is <NUM> mass%, the inorganic filler may generally account for <NUM> mass% or more, typically account for <NUM> mass% or more, and account for, for example, <NUM> mass% or more. The positive electrode protection layer 22p may contain an arbitrary component other than the inorganic filler, such as a conductive material, a binder, and various additive components. The conductive material and the binder may be the same as those that can be contained in the positive electrode active material layer 22a exemplified above.

As shown in <FIG>, the negative electrode <NUM> has a negative electrode collector 24c and a negative electrode active material layer 24a that is fixed onto at least one surface of the negative electrode collector 24c. The negative electrode collector 24c has a strip shape. The negative electrode collector 24c is made of, for example, conductive metal such as copper, a copper alloy, nickel, and stainless steel. Here, the negative electrode collector 24c is metal foil and specifically copper foil.

At one end (the right end in <FIG>) in the long side direction Y of the negative electrode collector 24c, a plurality of negative electrode tabs 24t are provided. The plurality of negative electrode tabs 24t protrude toward one side (the right side in <FIG>) in the long side direction Y. The plurality of negative electrode tabs 24t protrude farther in the long side direction Y than the separator <NUM>. The plurality of negative electrode tabs 24t are (intermittently) provided at intervals along the longitudinal direction of the negative electrode <NUM>. Here, the negative electrode tabs 24t are a part of the negative electrode collector 24c and made of metal foil (copper foil). Here, each of the plurality of negative electrode tabs 24t has a trapezoidal shape. Here, the negative electrode tabs 24t are portions (collector exposing parts) at which the negative electrode active material layer 24a of the negative electrode collector 24c is not formed. However, the negative electrode tabs 24t may be members different from the negative electrode collector 24c. Further, the negative electrode tabs 24t may be provided at the other end (the right end in <FIG>) in the long side direction Y, or may be provided at both respective ends in the long side direction Y.

As shown in <FIG>, the plurality of negative electrode tabs 24t are laminated with each other at the one end (the right end in <FIG>) in the long side direction Y and constitute a negative electrode tab group <NUM>. The plurality of negative electrode tabs 24t are folded and curved so as to make their outward-side ends aligned with each other. The negative electrode tab group <NUM> is electrically connected to the negative electrode terminal <NUM> via the negative electrode collecting part <NUM>. The plurality of negative electrode tabs 24t are preferably folded and electrically connected to the negative electrode terminal <NUM>. A negative electrode second collecting part <NUM> that will be described later is annexed to the negative electrode tab group <NUM>. The sizes (a length in the long side direction Y and a width orthogonal to the long side direction Y, see <FIG>) of the plurality of negative electrode tabs 24t may be appropriately adjusted according to, for example, their forming positions or the like in consideration of a state in which the plurality of negative electrode tabs 24t are connected to the negative electrode collecting part <NUM>. Here, the sizes of the plurality of negative electrode tabs 24t are different from each other so that the outward-side ends are aligned with each other when curved.

As shown in <FIG>, the negative electrode active material layer 24a is provided in a strip shape along the longitudinal direction of the strip-shaped negative electrode collector 24c. The negative electrode active material layer 24a contains a negative electrode active material (for example, a carbon material such as graphite) capable of reversibly occluding and releasing a charge carrier. When the entire solid content of the negative electrode active material layer 24a is <NUM> mass%, the negative electrode active material may generally account for <NUM> mass% or more, typically account for <NUM> mass% or more, and account for, for example, <NUM> mass% or more. The negative electrode active material layer 24a may contain an arbitrary component other than the negative electrode active material, such as a binder, a dispersing agent, and various additive components. As the binder, rubbers such as styrene butadiene rubber (SBR) can be, for example, used. As the dispersing agent, celluloses such as carboxymethyl cellulose (CMC) can be, for example, used.

The separator <NUM> is a member that insulates the positive electrode active material layer 22a of the positive electrode <NUM> and the negative electrode active material layer 24a of the negative electrode <NUM> from each other. The separator <NUM> constitutes the outside surface of the winding electrode body 20a. As the separator <NUM>, a resinous porous sheet made of a polyolefin resin such as polyethylene (PE) and polypropylene (PP) is, for example, suitable. Here, the separator <NUM> has a base material part made of a resinous porous sheet and a heat resistance layer (HRL) formed on at least one surface of the base material part. The heat resistance layer is typically a layer containing an inorganic filler and a binder. As the inorganic filler, alumina, boehmite, aluminum hydroxide, titania, or the like can be, for example, used. As the binder, polyvinylidene fluoride (PVdF) or the like can be, for example, used.

As shown in <FIG>, the winding electrode body 20a has a pair of curvature parts (R parts) 20r that face the bottom wall 12a of the exterior body <NUM> and the sealing plate <NUM> and a flat part 20f that connects the pair of curvature parts 20r to each other and faces the long side walls 12b of the exterior body <NUM>. Here, one (an upper one in <FIG>) of the curvature parts 20r indirectly faces the sealing plate <NUM> via a positive electrode first collecting part <NUM>, a negative electrode first collecting part <NUM>, the positive electrode insulating member <NUM>, the negative electrode insulating member <NUM>, or the like that will be described later. Here, the other (a lower one in <FIG>) of the curvature parts 20r indirectly faces the bottom wall 12a via the electrode body holder <NUM>. Note that although the winding electrode body 20a will be described in detail below as an example, the winding electrode bodies 20b and 20c may have the same configuration.

<FIG> is a partially-enlarged cross-sectional view schematically showing the vicinity of the upper end of the winding electrode body 20a in <FIG>. In <FIG>, a line perpendicular to the winding axis WL of the winding electrode body 20a and perpendicular to the bottom wall 12a is indicated as a line L1. Note that when the respective apexes (the upper end and the lower end of the winding electrode body 20a in <FIG>) of the pair of curvature parts 20r of the winding electrode body 20a are not crushed, a line connecting the pair of apexes to each other is more preferably assumed as the line L1.

In the curvature part 20r facing the sealing plate <NUM>, a portion 24o positioned at the outermost peripheral part of the negative electrode <NUM> faces a portion 24i positioned on the winding inner peripheral side of the negative electrode <NUM> via the separator <NUM> on the line L1. The portion 24o positioned at the outermost peripheral part of the negative electrode <NUM> does not face the positive electrode <NUM>. Thus, even if the winding electrode body 20a is strongly pressed by the bottom wall 12a of the exterior body <NUM> directly or via other members such as the electrode body holder <NUM> and the separator <NUM> is damaged, it is possible to prevent the short circuit between the portion 24o positioned at the outermost peripheral part of the negative electrode <NUM> and the positive electrode <NUM> positioned on the winding inner peripheral side. Further, even if the curvature part 20r of the winding electrode body 20a is strongly pressed by the protrusion part 70b of the positive electrode insulating member <NUM> and the separator <NUM> is damaged in an insertion step that will be described later, it is possible to prevent the short circuit between the portion 24o positioned at the outermost peripheral part of the negative electrode <NUM> and the positive electrode <NUM> positioned on the winding inner peripheral side. Note that the protrusion part 70b (spacer) of the positive electrode insulating member <NUM> that will be described later is particularly preferably positioned on the line L1. Thus, it is possible to improve the insertion of the winding electrode body 20a into the exterior body <NUM>. Further, it is possible to prevent the movement of the winding electrode body 20a toward the sealing plate <NUM>.

In the curvature part 20r, the portion closest to the protrusion part 70b of the positive electrode insulating member <NUM> crosses the line L1. In the portion of the curvature part 20r closest to the protrusion part 70b, the portion 24o positioned at the outermost peripheral part of the negative electrode <NUM> faces the portion 24i positioned on the winding inner peripheral side of the negative electrode <NUM> via the separator <NUM> on the line L1. The portion 24o positioned at the outermost peripheral part of the negative electrode <NUM> does not face the positive electrode <NUM>. Thus, the winding electrode body 20a is not liable to move greatly toward the sealing plate <NUM>. Therefore, it is possible to prevent damage on the separator <NUM> caused when the winding electrode body 20a contacts the sealing plate <NUM>. Thus, it is possible to effectively prevent the short circuit between the positive electrode <NUM> and the negative electrode <NUM>. Further, it is possible to reduce loads on the positive electrode tab group <NUM> and/or the negative electrode tab group <NUM> and stably maintain electrical connection with the positive electrode terminal <NUM> and/or the negative electrode terminal <NUM>. Thus, it is possible to improve the conduction reliability of the battery.

In a winding direction orthogonal to the winding axis WL, a winding terminal 22e of the positive electrode <NUM> is arranged closer to an inner peripheral side than a winding terminal 24e of the negative electrode <NUM>. The winding terminal 22e of the positive electrode <NUM> is preferably positioned at one of the curvature parts 20r. Here, the winding terminal 22e of the positive electrode <NUM> is positioned at the curvature part 20r facing the sealing plate <NUM>. With this configuration, it is possible to prevent the generation of a step at a position corresponding to the winding terminal 22e in the flat part 20f of the winding electrode body 20a. Thus, it is possible to prevent the slight short circuit or the like between the positive electrode and the negative electrode caused by the precipitation of metal lithium (dendrite) even when a large pressure is locally applied to the flat part 20f.

The winding terminal 22e of the positive electrode <NUM> is arranged closer to the winding inner peripheral side than the line L1. In <FIG>, a length from the winding terminal 22e of the positive electrode <NUM> to the line L1 is indicated as La. The length La is preferably <NUM> to <NUM>, more preferably <NUM> to <NUM>, and further more preferably <NUM> to <NUM>. The length La may be <NUM> or more. Thus, it is possible to more effectively prevent the short circuit between the positive electrode <NUM> and the negative electrode <NUM>.

A winding terminal 24e of the negative electrode <NUM> is arranged closer to a winding outer peripheral side than a winding terminal 22e of the positive electrode <NUM>. The winding terminal 24e of the negative electrode <NUM> is preferably positioned at one of the curvature parts 20r. Here, the winding terminal 24e of the negative electrode <NUM> is positioned at the curvature part 20r facing the sealing plate <NUM>. With this configuration, it is possible to prevent the generation of a step at a position corresponding to the winding terminal 24e in the flat part 20f of the winding electrode body 20a. Thus, even when a large pressure is locally applied to the flat part 20f, it is possible to prevent the slight short circuit or the like between the positive electrode and the negative electrode caused by the precipitation of metal lithium (dendrite).

The winding terminal 24e of the negative electrode <NUM> is arranged closer to the winding outer peripheral side than the line L1 (in other words, a position over the line L1). In <FIG>, a length from the line L1 to the winding terminal 24e of the negative electrode <NUM> is indicated as Lb. The length Lb is preferably <NUM> to <NUM>, more preferably <NUM> to <NUM>, and further more preferably <NUM> to <NUM>. Thus, it is possible to more effectively prevent the short circuit between the positive electrode <NUM> and the negative electrode <NUM>. However, the winding terminal 24e of the negative electrode <NUM> may be arranged on the line L1. The length Lb may be <NUM>.

In <FIG>, a length from the winding terminal 22e of the positive electrode <NUM> to the winding terminal 24e of the negative electrode <NUM> is indicated as La + Lb. The winding terminal 24e of the negative electrode <NUM> is arranged at a position ahead of the winding terminal 22e of the positive electrode <NUM> by the length La + Lb in the winding direction. The length La + Lb is preferably <NUM> or more, more preferably <NUM> to <NUM>, and further more preferably <NUM> to <NUM>. Thus, it is possible to more effectively prevent the short circuit between the positive electrode <NUM> and the negative electrode <NUM>.

A winding terminal 26e of the separator <NUM> is arranged closer to the winding outer peripheral side than the winding terminal 22e of the positive electrode <NUM> and the winding terminal 24e of the negative electrode <NUM>. The winding terminal 26e of the separator <NUM> is arranged at a position ahead of the winding terminal 24e of the negative electrode <NUM> in the winding direction. A fastening tape <NUM> is attached to the winding terminal 26e of the separator <NUM>. The fastening tape <NUM> is arranged at the flat part 20f so that its whole area does not put on the curvature part 20r.

The winding terminal 26e of the separator <NUM> is preferably positioned at the flat part 20f. With such a configuration, it is possible to effectively prevent a fluctuation in the thickness (the length in a short side direction X in <FIG>) of the plurality of winding electrode bodies 20a, 20b, and 20c. As a result, it is possible to charge and discharge the plurality of winding electrode bodies 20a, 20b, and 20c in a balanced manner. Note that a part of the fastening tape <NUM> could be arranged at the flat part 20f depending on circumstances when the winding terminal 26e of the separator <NUM> is arranged at one of the curvature parts 20r, which possibly results in a fluctuation in the thickness of the winding electrode body 20a.

The curvature part 20r facing the sealing plate <NUM> has a recessed part 20d. In the insertion step that will be described later, the recessed part 20d is formed when the winding electrode body 20a is pressed by the protrusion part 70b of the positive electrode insulating member <NUM> and/or the protrusion part 80b of the negative electrode insulating member <NUM>. Here, the recessed part 20d is formed between the winding terminal 22e of the positive electrode <NUM> and the winding terminal 24e of the negative electrode <NUM> (that is, within the range of the length La + Lb). At the recessed part 20d, the portion 24o positioned at the outermost peripheral part of the negative electrode <NUM> and the separator <NUM> are crushed so as to come close to the portion 24i positioned on the winding inner peripheral side of the negative electrode <NUM>.

Although omitted in the figures, the separator <NUM> has the heat resistance layer arranged closer to the side of the outside surface than the base material part on the outermost peripheries of the winding electrode bodies 20a, 20b, and 20c. The outside surfaces of the winding electrode bodies 20a, 20b, and 20c are covered with the heat resistance layer of the separator <NUM>. Since the outside surfaces of the winding electrode bodies 20a, 20b, and 20c are covered with the heat resistance layer at least at one of the pair of curvature parts 20r, it is possible to relax stress applied to the curvature parts 20r even if the curvature parts 20r contact the bottom wall 12a and/or the sealing plate <NUM>. Thus, the separator <NUM> is not liable to be damaged. Further, even if the separator <NUM> is damaged, it is possible to prevent the short circuit between the portion 24o positioned at the outermost peripheral part of the negative electrode <NUM> and the positive electrode <NUM> positioned on the winding inner peripheral side.

The electrolytic solution may be a conventional type and is not particularly limited. The electrolytic solution is, for example, a nonaqueous electrolytic solution containing a nonaqueous system solvent and supporting salt. The nonaqueous system solvent contains, for example, carbonates such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. The supporting salt is, for example, fluorine-containing lithium salt such as LiPF6. However, the electrolytic solution may be a solid state (solid electrolytic) and integrated with the electrode body group <NUM>.

The positive electrode collecting part <NUM> constitutes a conduction path that electrically connects the positive electrode tab group <NUM> including the plurality of positive electrode tabs 22t and the positive electrode terminal <NUM> to each other. As shown in <FIG>, the positive electrode collecting part <NUM> includes the positive electrode first collecting part <NUM> and the positive electrode second collecting part <NUM>. The positive electrode first collecting part <NUM> and the positive electrode second collecting part <NUM> may be made of the same metal type as that of the positive electrode collector 22c, for example, conductive metal such as aluminum, an aluminum alloy, nickel, and stainless steel.

<FIG> is a partially-enlarged cross-sectional view schematically showing the vicinity of the positive electrode terminal <NUM> in <FIG>. <FIG> is a perspective view schematically showing the sealing plate <NUM>. <FIG> is a perspective view in which the sealing plate in <FIG> is reversed. <FIG> shows the surface on the side (inside) of the exterior body <NUM> of the sealing plate <NUM>. As shown in <FIG>, the positive electrode first collecting part <NUM> is attached to the inside surface of the sealing plate <NUM>. The positive electrode first collecting part <NUM> is an example of a collecting part disclosed here. The positive electrode first collecting part <NUM> has a first region 51a and a second region 51b. The positive electrode first collecting part <NUM> may be configured in such a manner that one member is folded by, for example, press work or the like, or may be configured in such a manner that a plurality of members are integrated with each other by welding joint or the like. Here, the positive electrode first collecting part <NUM> is fixed to the sealing plate <NUM> by caulking work.

The first region 51a is a portion arranged between the sealing plate <NUM> and the electrode body group <NUM>. The first region 51a extends along the long side direction Y. The first region 51a spreads horizontally along the inside surface of the sealing plate <NUM>. The positive electrode insulating member <NUM> is arranged between the sealing plate <NUM> and the first region 51a. The first region 51a is insulated from the sealing plate <NUM> by the positive electrode insulating member <NUM>. Here, the first region 51a is electrically connected to the positive electrode terminal <NUM> by caulking work. In the first region 51a, a through-hole <NUM> penetrating in the vertical direction Z is formed at a position corresponding to the terminal withdrawing hole <NUM> of the sealing plate <NUM>. The second region 51b is a portion arranged between the short side wall 12c of the exterior body <NUM> and the electrode body group <NUM>. The second region 51b extends from one side end (the left end in <FIG>) in the long side direction Y of the first region 51a to the short side wall 12c of the exterior body <NUM>. The second region 51b extends along the vertical direction Z.

The positive electrode second collecting part <NUM> extends along the short side wall 12c of the exterior body <NUM>. As shown in <FIG>, the positive electrode second collecting part <NUM> has a collecting plate connection part 52a, an inclined part 52b, and a tab joining part 52c. The collecting plate connection part 52a is a portion electrically connected to the positive electrode first collecting part <NUM>. The collecting plate connection part 52a extends along the vertical direction Z. The collecting plate connection part 52a is arranged substantially perpendicular to the winding axis WL of the winding electrode bodies 20a, 20b, and 20c. The collecting plate connection part 52a is provided with a recessed part 52d thinner than its periphery. The recessed part 52d is provided with a through-hole 52e penetrating in the short side direction X. The through-hole 52e has a joining part joined to the positive electrode first collecting part <NUM>. The joining part is, for example, a weld joining part formed by welding such as ultrasonic wave welding, resistance welding, and laser welding. The positive electrode second collecting part <NUM> may be provided with a fuse.

The tab joining part 52c is a portion annexed to the positive electrode tab group <NUM> and electrically connected to the plurality of positive electrode tabs 22t. As shown in <FIG>, the tab joining part 52c extends along the vertical direction Z. The tab joining part 52c is arranged substantially perpendicular to the winding axis WL of the winding electrode bodies 20a, 20b, and 20c. The surface of the tab joining part 52c that is connected to the plurality of positive electrode tabs 22t is arranged substantially parallel to the short side wall 12c of the exterior body <NUM>. As shown in <FIG>, the tab joining part 52c has a joining part J joined to the positive electrode tab group <NUM>. The joining part J is, for example, a welding joint part formed by welding such as ultrasonic wave welding, resistance welding, and laser welding in a state in which the plurality of positive electrode tabs 22t are overlapped with each other. The welding joint part is arranged with the plurality of positive electrode tabs 22t approaching one side in the short side direction X of the winding electrode bodies 20a, 20b, and 20c. Thus, it is possible to more suitably fold the plurality of positive electrode tabs 22t and stably form the positive electrode tab group <NUM> having a curvature shape as shown in <FIG>.

The inclined part 52b is a portion that connects the lower end of the collecting plate connection part 52a and the upper end of the tab joining part 52c to each other. The inclined part 52b is inclined with respect to the collecting plate connection part 52a and the tab joining part 52c. The inclined part 52b connects the collecting plate connection part 52a and the tab joining part 52c to each other so that the collecting plate connection part 52a is positioned closer to a central side than the tab joining part 52c in the long side direction Y. Thus, it is possible to expand the accommodation space of the electrode body group <NUM> to increase the high energy density of the battery <NUM>. The lower end (in other words, the end on the side of the bottom wall 12a of the exterior body <NUM>) of the inclined part 52b is preferably positioned below the lower end of the positive electrode tab group <NUM>. Thus, it is possible to more suitably fold the plurality of positive electrode tabs 22t and stably form the positive electrode tab group <NUM> having a curvature shape as shown in <FIG>.

The negative electrode collecting part <NUM> constitutes a conduction path that electrically connects the negative electrode tab group <NUM> including the plurality of negative electrode tabs 24t and the negative electrode terminal <NUM> to each other. As shown in <FIG>, the negative electrode collecting part <NUM> includes the negative electrode first collecting part <NUM> and the negative electrode second collecting part <NUM>. The negative electrode first collecting part <NUM> is an example of a collecting part disclosed here. The negative electrode first collecting part <NUM> and the negative electrode second collecting part <NUM> may be made of the same metal type as that of the negative electrode collector 24c, for example, conductive metal such as copper, a copper alloy, nickel, and stainless steel. The configurations of the negative electrode first collecting part <NUM> and the negative electrode second collecting part <NUM> may be the same as those of the positive electrode first collecting part <NUM> and the positive electrode second collecting part <NUM> of the positive electrode collecting part <NUM>.

As shown in <FIG>, the negative electrode first collecting part <NUM> has a first region 61a and a second region 61b. The negative electrode insulating member <NUM> is arranged between the sealing plate <NUM> and the first region 61a. The first region 61a is insulated from the sealing plate <NUM> by the negative electrode insulating member <NUM>. In the first region 61a, a through-hole <NUM> penetrating in the vertical direction Z is formed at a position corresponding to the terminal withdrawing hole <NUM> of the sealing plate <NUM>. As shown in <FIG>, the negative electrode second collecting part <NUM> has a collecting plate connection part 62a electrically connected to the negative electrode first collecting part <NUM>, an inclined part 62b, and a tab joining part 62c that is annexed to the negative electrode tab group <NUM> and electrically connected to the plurality of negative electrode tabs 24t. The collecting plate connection part 62a has a recessed part 62d connected to the tab joining part 62c. The recessed part 62d is provided with a through-hole 62e penetrating in the short side direction X.

The positive electrode insulating member <NUM> is a member that insulates the sealing plate <NUM> and the positive electrode first collecting part <NUM> from each other. Note that although the positive electrode insulating member <NUM> will be described in detail below as an example, the negative electrode insulating member <NUM> may have the same configuration. The positive electrode insulating member <NUM> preferably has resistance and electrical insulating properties with respect to a used electrolytic solution, made of an elastically-deformable resin material, and made of, for example, a polyolefin resin such as polypropylene (PP), a fluorinated resin such as tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA), polyphenylene sulfide (PPS), or the like.

As shown in <FIG>, the positive electrode insulating member <NUM> has the base part 70a and the plurality of protrusion parts 70b. Here, the base part 70a and the protrusion parts 70b are integrally molded. Here, the positive electrode insulating member <NUM> is an integrated molded article obtained by integrally molding resin materials as described above. Thus, compared with a case in which the base part 70a and the protrusion parts 70b are members different from each other, it is possible to reduce the number of used members and realize cost reduction. Further, it is possible to more easily prepare the positive electrode insulating member <NUM>.

The base part 70a is a portion arranged between the sealing plate <NUM> and the first region 51a of the positive electrode first collecting part <NUM> in the vertical direction Z. The base part 70a spreads horizontally along the first region 51a of the positive electrode first collecting part <NUM>. As shown in <FIG>, the base part 70a has a through-hole <NUM> penetrating in the vertical direction Z. The through-hole <NUM> is formed at a position corresponding to the terminal withdrawing hole <NUM> of the sealing plate <NUM>.

Each of the plurality of protrusion parts 70b protrudes closer to the side of the electrode body group <NUM> than the base part 70a. As shown in <FIG>, the plurality of protrusion parts 70b are provided closer to the central side (the right side in <FIG>) of the sealing plate <NUM> than the base part 70a in the long side direction Y. The plurality of protrusion parts 70b are arranged side by side in the short side direction X. As shown in <FIG>, the plurality of protrusion parts 70b here face the curvature parts 20r of the winding electrode bodies 20a, 20b, and 20c constituting the electrode body group <NUM>. Thus, it is possible to prevent the end surfaces of the winding electrode bodies 20a, 20b, and 20c from being pressed by the protrusion parts 70b and damaged.

Here, the number of the protrusion parts 70b is the same as the number of the winding electrode bodies 20a, 20b, and 20c constituting the electrode body group <NUM>, i.e., three. Thus, it is possible to make the winding electrode bodies 20a, 20b, and 20c and the protrusion parts 70b more reliably face each other and more effectively exhibit the effect of the technology disclosed here. Further, it is possible to make the winding electrode bodies 20a, 20b, and 20c and the protrusion parts 70b contact each other in a balanced manner in the insertion step that will be described later. However, the number of the protrusion parts 70b may be different from the number of electrode bodies constituting the electrode body group <NUM>, and may be, for example, one.

As shown in <FIG>, the protrusion parts 70b are formed in a substantially U-shape in cross section. In the vertical direction Z, the protrusion parts 70b preferably protrude closer to the side of the electrode body group <NUM> than the surface on the side of the electrode body group <NUM> of the first region 51a. The protrusion parts 70b do not preferably contact the winding electrode bodies 20a, 20b, and 20c constituting the electrode body group <NUM>. The plurality of protrusion parts 70b are preferably arranged at positions separated from the winding electrode bodies 20a, 20b, and 20c. In the vertical direction Z, a length Ha of the winding electrode body 20a is preferably smaller than a distance Hb from the lower ends of the protrusion parts 70b to the bottom wall 12a of the exterior body <NUM> (i.e., Ha < Hb). Thus, even if the winding electrode bodies 20a, 20b, and 20c move toward the sealing plate <NUM>, it is possible to prevent the curvature parts 20r and the protrusion parts 70b from rubbing against each other. Accordingly, the separator <NUM> is not liable to be damaged, which makes it possible to effectively prevent the short circuit between the positive electrode <NUM> and the negative electrode <NUM>. The shortest distance D between the protrusion parts 70b and the winding electrode bodies 20a, 20b, and 20c may be generally <NUM> or more.

The shortest distance D between the protrusion parts 70b and the winding electrode bodies 20a, 20b, and 20c is preferably <NUM> or less, more preferably <NUM> or less, and further more preferably <NUM> or less. Thus, it is possible to more effectively prevent the curvature parts 20r and the protrusion parts 70b from rubbing against each other. However, the protrusion parts 70b and the winding electrode bodies 20a, 20b, and 20c may contact each other in other embodiments.

Although not particularly limited, the area of a region <NUM> at the shortest distance D from the winding electrode body 20a in the protrusion part 70b is generally preferably <NUM>% to <NUM>%, more preferably <NUM>% to <NUM>%, and further more preferably <NUM>% to <NUM>% when it is assumed that the area of the winding electrode body 20a in a top view is <NUM>%. Thus, even if the protrusion part 70b contacts the winding electrode body 20a in the insertion step that will be described later, it is possible to effectively prevent the short circuit between the positive electrode <NUM> and the negative electrode <NUM>. Here, the region <NUM> at the shortest distance D from the winding electrode body 20a has a flat surface on the side of the winding electrode bodies 20a, 20b, and 20c. However, the region <NUM> may have a shape along the outside surface (upper surface) of each of the winding electrode bodies 20a, 20b, and 20c, specifically a curved shape along the curvature part 20r.

As shown in <FIG>, the negative electrode insulating member <NUM> is arranged symmetrically with the positive electrode insulating member <NUM> with respect to a center CL in the long side direction Y of the electrode body group <NUM>. The configuration of the negative electrode insulating member <NUM> may be the same as that of the positive electrode insulating member <NUM>. Here, the negative electrode insulating member <NUM> has the base part 80a arranged between the sealing plate <NUM> and the negative electrode first collecting part <NUM> and the plurality of protrusion parts 80b like the positive electrode insulating member <NUM>.

The battery <NUM> preferably includes both the positive electrode insulating member <NUM> and the negative electrode insulating member <NUM>. Thus, even if vibration, shock, or the like is applied during the use of the battery <NUM>, the electrode body group <NUM> and the sealing plate <NUM> are easily maintained in a parallel state (a state in <FIG>). Further, in the insertion step that will be described later, it is possible to make the electrode body group <NUM> and the protrusion parts 70b contact each other more suitably (for example, in a balanced manner in the long side direction Y) and stably press the electrode body group <NUM> by the protrusion parts 70b to be inserted into the exterior body <NUM>.

A manufacturing method for the battery <NUM> is characterized by using the winding electrode bodies 20a, 20b, and 20c as described above. Other manufacturing processes may be the same as those of conventional technologies. The battery <NUM> may be manufactured by a manufacturing method in which the battery case <NUM> (the exterior body <NUM> and the sealing plate <NUM>), the electrode body group <NUM> (the winding electrode bodies 20a, 20b, and 20c), the electrolytic solution, the positive electrode terminal <NUM>, the negative electrode terminal <NUM>, the positive electrode collecting part <NUM> (the positive electrode first collecting part <NUM> and the positive electrode second collecting part <NUM>), and the negative electrode collecting part <NUM> (the negative electrode first collecting part <NUM> and the negative electrode second collecting part <NUM>) as described above are prepared in addition to the positive electrode insulating member <NUM> and the negative electrode insulating member <NUM>, and which includes, for example, a first attachment step, a second attachment step, an insertion step, and a sealing step in this order. Further, the manufacturing method disclosed here may further include other steps in arbitrary stages.

In the first attachment step, a first united object as shown in <FIG> and <FIG> is manufactured. Specifically, the positive electrode terminal <NUM>, the positive electrode first collecting part <NUM>, the positive electrode insulating member <NUM>, the negative electrode terminal <NUM>, the negative electrode first collecting part <NUM>, and the negative electrode insulating member <NUM> are first attached to the sealing plate <NUM>.

The positive electrode terminal <NUM>, the positive electrode first collecting part <NUM>, and the positive electrode insulating member <NUM> are fixed to the sealing plate <NUM> by, for example, caulking work (riveting). As shown in <FIG>, the caulking work is performed with the gasket <NUM> held between the outside surface of the sealing plate <NUM> and the positive electrode terminal <NUM> and also with the positive electrode insulating member <NUM> held between the inside surface of the sealing plate <NUM> and the positive electrode first collecting part <NUM>. Note that the material of the gasket <NUM> may be the same as that of the positive electrode insulating member <NUM>. Specifically, the positive electrode terminal <NUM> before the caulking work is inserted into a through-hole <NUM> of the gasket <NUM>, the terminal withdrawing hole <NUM> of the sealing plate <NUM>, the through-hole <NUM> of the positive electrode insulating member <NUM>, and the through-hole <NUM> of the positive electrode first collecting part <NUM> in order from above the sealing plate <NUM> and caused to protrude below the sealing plate <NUM>. Then, the portion of the positive electrode terminal <NUM> protruding below the sealing plate <NUM> is caulked so that a compressive force is applied in the vertical direction Z. Thus, a caulking part 30c is formed at the tip end (the lower end in <FIG>) of the positive electrode terminal <NUM>.

By such caulking work, the gasket <NUM>, the sealing plate <NUM>, the positive electrode insulating member <NUM>, and the positive electrode first collecting part <NUM> are integrally fixed to the sealing plate <NUM> and the terminal withdrawing hole <NUM> is sealed. Note that the caulking part 30c may be welded and joined to the positive electrode first collecting part <NUM>. Thus, it is possible to further improve conduction reliability.

The fixation between the negative electrode terminal <NUM>, the negative electrode first collecting part <NUM>, and the negative electrode insulating member <NUM> may be performed like the case of the positive electrode described above. That is, the negative electrode terminal <NUM> before caulking work is inserted into the through-hole of a gasket, the terminal withdrawing hole <NUM> of the sealing plate <NUM>, the through-hole of the negative electrode insulating member <NUM>, and the through-hole of the negative electrode first collecting part <NUM> in order from above the sealing plate <NUM> and caused to protrude below the sealing plate <NUM>. Then, the portion of the negative electrode terminal <NUM> protruding below the sealing plate <NUM> is caulked so that a compressive force is applied in the vertical direction Z. Thus, a caulking part 40c is formed at the tip end (the lower end in <FIG>) of the negative electrode terminal <NUM>.

Next, a positive electrode outside conductive member <NUM> and a negative electrode outside conductive member <NUM> are attached to the outside surface of the sealing plate <NUM> via the outside insulating members <NUM>. Note that the material of the outside insulating members <NUM> may be the same as that of the positive electrode insulating member <NUM>. Further, a timing at which the positive electrode outside conductive member <NUM> and the negative electrode outside conductive member <NUM> are attached may be set after the insertion step (for example, after the solution injection hole <NUM> is sealed).

In the second attachment step, a second united object as shown in <FIG> is manufactured using the first united object manufactured in the first attachment step. Specifically, three winding electrode bodies 20a to which the positive electrode second collecting part <NUM> and the negative electrode second collecting part <NUM> are annexed as shown in <FIG> are first prepared and arranged side by side in the short side direction X as the winding electrode bodies 20a, 20b, and 20c. At this time, the winding electrode bodies 20a, 20b, and 20c may be arranged in parallel so that the positive electrode second collecting part <NUM> is arranged on one side (the left side in <FIG>) in the long side direction Y and the negative electrode second collecting part <NUM> is arranged on the other side (the right side in <FIG>) in the long side direction Y.

Next, in a state in which the plurality of positive electrode tabs 22t are curved as shown in <FIG>, the positive electrode first collecting part <NUM> (specifically, the second region 51b) fixed to the sealing plate <NUM> and the positive electrode second collecting part <NUM> (specifically, the collecting plate connection part 52a) of the winding electrode bodies 20a, 20b, and 20c are joined to each other. Further, in a state in which the plurality of negative electrode tabs 24t of the negative electrode tab group <NUM> are curved, the negative electrode first collecting part <NUM> fixed to the sealing plate <NUM> and the negative electrode second collecting part <NUM> of the winding electrode bodies 20a, 20b, and 20c are joined to each other. As a joining method, welding such as ultrasonic wave welding, resistance welding, and laser welding may be used. Particularly, welding by the irradiation of high-energy rays such as laser beams is preferably used. By such welding work, a joining part is formed on each of the recessed part 52d of the positive electrode second collecting part <NUM> and the recessed part 62d of the negative electrode second collecting part <NUM>.

In the insertion step, the electrode body group <NUM> integrated with the sealing plate <NUM> is accommodated in the inside space of the exterior body <NUM>. <FIG> is a schematic cross-sectional view for describing the insertion step. Specifically, an insulative resin sheet made of a resin material such as polyethylene (PE) is, for example, first folded in a bag shape or a box shape to prepare the electrode body holder <NUM>. Next, the electrode body group <NUM> is accommodated in the electrode body holder <NUM>. Then, the electrode body group <NUM> covered with the electrode body holder <NUM> is inserted into the exterior body <NUM>. When the weight of the electrode body group <NUM> is heavy, i. e, when the electrode body group <NUM> generally weighs <NUM> or more, weighs, for example, <NUM> or more, or weighs <NUM> to <NUM>, the electrode body group <NUM> may be inserted into the exterior body <NUM> (with the exterior body <NUM> turned sideways) so that the long side walls 12b of the exterior body <NUM> cross a gravity direction as shown in <FIG>.

Each of the curvature parts 20r of the winding electrode bodies 20a, 20b, and 20c constituting the electrode body group <NUM> is pressed by the protrusion parts 70b of the positive electrode insulating member <NUM> and/or the protrusion parts 80b of the negative electrode insulating member <NUM> that serve as spacers and pressed into the exterior body <NUM>. By pressing the electrode body group <NUM> by the protrusion parts 70b and/or the protrusion parts 80b, it is possible to reduce loads on the positive electrode tab group <NUM> and/or the negative electrode tab group <NUM>. When the electrode body group <NUM> is attached to the exterior body <NUM>, the protrusion parts 70b and/or the protrusion parts 80b that serve as spacers can function as buffering members that reduce loads on the positive electrode tab group <NUM> and/or the negative electrode tab group <NUM>.

At this time, the protrusion parts 70b and/or the protrusion parts 80b preferably thrust the winding electrode bodies 20a, 20b, and 20c in a state of getting in the curvature parts 20r on one side of the winding electrode bodies 20a, 20b, and 20c. Thus, it is possible to make the positive electrode insulating member <NUM> and/or the negative electrode insulating member <NUM> tightly contact the winding electrode bodies 20a, 20b, and 20c and prevent the positive electrode insulating member <NUM> and/or the negative electrode insulating member <NUM> from sliding against the winding electrode bodies 20a, 20b, and 20c. As a result of thrusting the winding electrode bodies 20a, 20b, and 20c in this manner, the recessed parts 20d are formed at the portions of the winding electrode bodies 20a, 20b, and 20c that face the protrusion parts 70b and/or the protrusion parts 80b.

The positive electrode tab group <NUM> and/or the negative electrode tab group <NUM> have play so as to be movable in a direction crossing their protruding direction. Therefore, when the exterior body <NUM> is raised so as to make the sealing plate <NUM> positioned on an upper side after the electrode body group <NUM> is inserted into the exterior body <NUM>, the electrode body group <NUM> slightly moves downward due to its own weight. Thus, as shown in <FIG>, the protrusion parts 70b of the positive electrode insulating member <NUM> and the winding electrode bodies 20a, 20b, and 20c are arranged at separated positions. Further, the protrusion parts 80b of the negative electrode insulating member <NUM> and the winding electrode bodies 20a, 20b, and 20c are arranged at separated positions.

In the sealing step, the sealing plate <NUM> is joined to the edge part of the opening <NUM> of the exterior body <NUM> to seal the opening <NUM>. The joining of the sealing plate <NUM> may be performed by, for example, welding such as laser welding. After that, an electrolytic solution is injected from the solution injection hole <NUM>, and the solution injection hole <NUM> is sealed by the sealing member <NUM> to tightly close the battery <NUM>.

In the manner described above, it is possible to manufacture the battery <NUM>.

The battery <NUM> is available for various applications but may be suitably used in an application in which an external force such as vibration and shock can be applied during use. For example, the battery <NUM> may be suitably used as a power source (driving power) for a motor mounted in a mobile body (typically, a vehicle such as an automobile and a truck). The type of the vehicle is not particularly limited but examples of the vehicle include a plug-in hybrid vehicle (PHV), a hybrid vehicle (HV), and an electric vehicle (EV). The battery <NUM> may be suitably used as a battery pack in which a plurality of the batteries <NUM> are arranged in a prescribed array direction and a load is added by a constraint mechanism in the array direction. Even in a state in which a load is added by the constraint mechanism, the protrusion parts 70b of the positive electrode insulating member <NUM> and/or the protrusion parts 80b of the negative electrode insulating member <NUM>, and the winding electrode bodies 20a, 20b, and 20c do not preferably contact each other.

For example, in the above embodiments, the winding terminal 24e of the negative electrode <NUM> is arranged at the curvature part 20r of the winding electrode body 20a. However, the winding terminal 24e of the negative electrode <NUM> may be arranged at other places. The winding terminal 24e of the negative electrode <NUM> may be arranged at the flat part 20f. With such a configuration, the shape of the outside surface of the curvature part 20r is secured. Thus, a gap is not liable to be generated between the vicinity of the winding terminal 22e of the positive electrode <NUM> and the facing negative electrode <NUM> in the curvature part 20r. As a result, it is possible to prevent the slight short circuit or the like between the positive electrode and the negative electrode caused by the precipitation of metal lithium (dendrite).

Claim 1:
A battery (<NUM>) comprising:
an exterior body (<NUM>) having a bottom wall (12a), a pair of first side walls (12b) extending from the bottom wall (12a) and facing each other, a pair of second side walls (12c) extending from the bottom wall (12a) and facing each other, and an opening (<NUM>) facing the bottom wall (12a);
a sealing plate (<NUM>) that seals the opening (<NUM>) of the exterior body (<NUM>);
at least one winding electrode body (20a) in which a strip-shaped positive electrode (<NUM>) and a strip-shaped negative electrode (<NUM>) are laminated with each other via a strip-shaped separator (<NUM>) and wound about a winding axis (WL);
a positive electrode tab group (<NUM>) that includes a plurality of positive electrode tabs (22t) provided at an end in a winding axis direction of the winding electrode body (20a) and is electrically connected to the positive electrode (<NUM>); and
a negative electrode tab group (<NUM>) that includes a plurality of negative electrode tabs (24t) provided at an end in the winding axis direction of the winding electrode body (20a) and is electrically connected to the negative electrode (<NUM>), wherein
the winding electrode body (20a) has a flat shape having a pair of curvature parts (20r) having a curved outside surface and a flat part (20f) that connects the pair of curvature parts (20r) to each other and has a flat outside surface and is accommodated in the exterior body (<NUM>) so that one of the curvature parts (20r) faces the sealing plate (<NUM>) and the other thereof faces the bottom wall (12a) of the exterior body (<NUM>), and
wherein, when a line perpendicular to the winding axis (WL) of the winding electrode body (20a) and perpendicular to the bottom wall (12a) is assumed as L1, a portion positioned at an outermost periphery of the negative electrode (<NUM>) in at least one of the pair of the curvature parts (20f) faces a portion positioned on a winding inner peripheral side of the negative electrode (<NUM>) via the separator (<NUM>) and not via the positive electrode (<NUM>) on the line L1.