JP2016149370A - Power storage element, electrode body, and core member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage element capable of improving uniformity of stress that an electrode body receives from a container.SOLUTION: A power storage element 10 includes an electrode body 400 formed by a positive electrode, a negative electrode, and a separator, being wound around a winding axis. The electrode body 400 includes a core member 410b disposed inside the innermost circumference of the wound positive electrode, negative electrode, and separator. The core member 410b is formed of a material whose rigidity is lower at an end part in a longer direction in a cross-section vertical to the winding axis than a center part.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a power storage element including an electrode body formed by winding a positive electrode, a negative electrode, and a separator, an electrode body, and a core material disposed on the innermost periphery of the electrode body.

  The shift from gasoline cars to electric cars has become important as a global environmental problem. For this reason, development of an electric vehicle using a power storage element such as a lithium ion secondary battery as a power source is being promoted.

  Here, in a conventional power storage element, a wound type power storage element in which an electrode body is formed by winding a positive electrode, a negative electrode, and a separator around a winding axis is widely known (for example, see Patent Document 1). Such a wound-type power storage element is manufactured by extracting a winding shaft after forming an electrode body and inserting the electrode body into a container.

JP 2000-156241 A

  However, in the conventional wound type electricity storage element, when the electrode body is inserted into the container, the stress that the electrode body receives from the container becomes non-uniform depending on the position of the electrode body, so that the performance of the electricity storage element decreases. There's a problem.

  FIG. 9 is a diagram for explaining a problem of a conventional wound-type energy storage device. As shown to (a) of the figure, in the electrode body from which the winding shaft was extracted, the space where the winding shaft was arrange | positioned in the center part is formed. When the electrode body is inserted into the container, the electrode body is deformed so that the width A of the end portion of the electrode body is larger than the width B of the center portion as shown in FIG. To do.

  For this reason, when the electrode body is inserted into the container, the insertion coefficient (the outer dimension of the electrode body / the inner dimension of the case) varies depending on the position of the electrode body. As a result, the stress that the electrode body receives from the container becomes non-uniform depending on the position of the electrode body, so that the durability of the electrode body (cycle durability characteristics) is reduced and the performance of the electricity storage device is reduced.

  The present invention has been made to solve the above-described problem, and is disposed in the innermost circumference of the electricity storage element, the electrode body, and the electrode body that can improve the uniformity of stress that the electrode body receives from the container. An object of the present invention is to provide a core material.

  In order to achieve the above object, a power storage device according to one embodiment of the present invention is a power storage device including an electrode body formed by winding a positive electrode, a negative electrode, and a separator around a winding axis, the electrode The body includes a core material disposed at an innermost inner periphery of the wound positive electrode, the negative electrode, and the separator, and the core material is a longitudinal end portion in a cross section perpendicular to the winding axis. Is made of a material having lower rigidity than the central portion.

  According to this, the power storage element includes a core material having a lower rigidity at the end portion in the longitudinal direction in the cross section perpendicular to the winding axis than at the central portion on the innermost periphery of the electrode body. That is, since the innermost periphery of the electrode body is provided with a core material whose end portion is more easily deformed than the central portion when stress is applied from the outside, the electrode body shown in FIG. The electrode body is deformed so that the width A of the end of the electrode approaches the length of the width B of the central portion. For this reason, the uniformity of the insertion coefficient when the electrode body is inserted into the container can be improved, and the uniformity of the stress that the electrode body receives from the container can be improved. Thereby, since durability of an electrode body can be improved, the performance of an electrical storage element can be improved.

  In addition, the present invention can be realized not only as such a power storage element, but also as an electrode body included in the power storage element or a core material included in the electrode body.

  According to the present invention, the uniformity of stress that the electrode body receives from the container can be improved, and the performance of the electricity storage device can be improved.

It is an external appearance perspective view of the electrical storage element which concerns on embodiment of this invention. It is a figure which shows the structure of the electrode body which concerns on embodiment of this invention. It is a perspective view which shows the structure of the core material which concerns on embodiment of this invention. It is a perspective view which shows the structure of the winding shaft which concerns on embodiment of this invention. It is a figure for demonstrating the manufacturing method of the electrode body which concerns on embodiment of this invention. It is a figure which shows the state in which the electrode body which concerns on embodiment of this invention was accommodated inside the container. It is a perspective view which shows the structure of the core material which concerns on the modification 1 of embodiment of this invention. It is a perspective view which shows the structure of the core material which concerns on the modification 2 of embodiment of this invention. It is a figure for demonstrating the problem of the conventional winding type electrical storage element.

  Hereinafter, a power storage element, an electrode body, a core material disposed on the innermost circumference of the electrode body, and a winding shaft will be described with reference to the drawings.

  Each of the embodiments described below shows a preferred specific example of the present invention. Numerical values, shapes, materials, constituent elements, arrangement positions and connection forms of constituent elements, and the like shown in the following embodiments are merely examples, and are not intended to limit the present invention. The invention is specified by the claims. Therefore, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims indicating the highest concept of the present invention are not necessarily required to achieve the object of the present invention. It will be described as constituting a preferred form.

  First, the configuration of the power storage element 10 will be described.

  FIG. 1 is an external perspective view of a power storage device 10 according to an embodiment of the present invention. In addition, the figure is a figure which saw through the container inside.

  The storage element 10 is a secondary battery that can charge electricity and discharge electricity, and more specifically, is a non-aqueous electrolyte battery such as a lithium ion secondary battery.

  As shown in the figure, the power storage element 10 includes a container 100, a positive electrode terminal 200, and a negative electrode terminal 300, and the container 100 includes a lid plate 110 that is an upper wall. In addition, an electrode body 400, a positive electrode current collector 120, and a negative electrode current collector 130 are disposed inside the container 100.

  Note that a liquid such as an electrolytic solution is sealed inside the container 100 of the power storage element 10, but the liquid is not shown. Moreover, the electrical storage element 10 is not limited to a non-aqueous electrolyte battery, and may be a secondary battery other than the non-aqueous electrolyte battery or a capacitor.

  The container 100 includes a casing body having a rectangular cylindrical shape made of metal and having a bottom, and a metal lid plate 110 that closes an opening of the casing body. In addition, the container 100 can be hermetically sealed by welding the lid plate 110 and the housing body after the electrode body 400 and the like are accommodated therein.

  The electrode body 400 includes a positive electrode, a negative electrode, and a separator, and is a member that can store electricity. Specifically, the electrode body 400 is formed by winding a layered arrangement so that a separator is sandwiched between a negative electrode and a positive electrode so that the whole becomes an oval shape. The detailed configuration of the electrode body 400 will be described later.

  The positive electrode terminal 200 is an electrode terminal electrically connected to the positive electrode of the electrode body 400, and the negative electrode terminal 300 is an electrode terminal electrically connected to the negative electrode of the electrode body 400. That is, the positive electrode terminal 200 and the negative electrode terminal 300 lead the electricity stored in the electrode body 400 to the external space of the power storage element 10, and in order to store the electricity in the electrode body 400, It is an electrode terminal made of metal for introducing. The positive electrode terminal 200 and the negative electrode terminal 300 are attached to a lid plate 110 disposed above the electrode body 400.

  The positive electrode current collector 120 is disposed between the positive electrode of the electrode body 400 and the side wall of the container 100, and is a member having conductivity and rigidity that is electrically connected to the positive electrode terminal 200 and the positive electrode of the electrode body 400. It is. The positive electrode current collector 120 is made of aluminum, like the positive electrode of the electrode body 400.

  The negative electrode current collector 130 is disposed between the negative electrode of the electrode body 400 and the side wall of the container 100, and is a member having conductivity and rigidity that is electrically connected to the negative electrode terminal 300 and the negative electrode of the electrode body 400. It is. The negative electrode current collector 130 is made of copper, like the negative electrode of the electrode body 400.

  Next, a detailed configuration of the electrode body 400 will be described.

  FIG. 2 is a diagram showing the configuration of the electrode body 400 according to the embodiment of the present invention. Specifically, this figure is a cross-sectional view when the electrode body 400 shown in FIG. 1 is cut along the YZ plane.

  As shown in the figure, the electrode body 400 includes a core material 410 and an electrode portion 420 disposed around the core material 410.

  Specifically, the electrode part 420 includes a positive electrode, a negative electrode, and a separator, and the positive electrode, the negative electrode, and the separator are wound around a winding axis. That is, the electrode body 400 is a wound electrode body. Here, the winding axis is a central axis when the positive electrode, the negative electrode, and the separator are wound.

  The positive electrode is obtained by forming a positive electrode active material layer on the surface of a long belt-like positive electrode base material made of aluminum foil. In addition, the positive electrode used for the electrical storage element 10 according to the present invention is not particularly different from those conventionally used, and those normally used can be used.

For example, as the positive electrode active material, polyanion compounds such as LiMPO ₄ , LiMSiO ₄ , LiMBO ₃ (M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.), lithium titanate, etc. , Spinel compounds such as lithium manganate, lithium transition metal oxides such as LiMO ₂ (M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.), etc. can be used. .

  In the negative electrode, a negative electrode active material layer is formed on the surface of a long strip-shaped negative electrode substrate made of copper foil. In addition, the negative electrode used for the electrical storage element 10 according to the present invention is not particularly different from those conventionally used, and those normally used can be used.

For example, as the negative electrode active material, lithium metal, lithium alloy (lithium metal-containing alloys such as lithium-aluminum, lithium-lead, lithium-tin, lithium-aluminum-tin, lithium-gallium, and wood alloy), lithium Alloys, carbon materials (eg, graphite, non-graphitizable carbon, graphitizable carbon, low-temperature calcined carbon, amorphous carbon, etc.), metal oxides, lithium metal oxides (Li ₄ Ti ₆ O ₁₂ Etc.) and polyphosphoric acid compounds.

  The core material 410 is an insulating member arranged on the innermost inner periphery of the electrode portion 420. Specifically, the core material 410 is a core made of resin such as polypropylene or polyethylene, which is disposed on the innermost inner periphery of the wound positive electrode, negative electrode, and separator. That is, the electrode body 400 is formed by winding the positive electrode, the negative electrode, and the separator around the core material 410.

  The core material 410 may be a wound sheet wheel formed by winding a resin sheet, or may be a molded member. Moreover, the core material 410 may be an integrally formed member, or may be formed of a plurality of members. Moreover, the material of the core material 410 is not specifically limited. For example, when a separator is disposed at a position closest to the core material in the electrode body 400, or when the potential of either the positive electrode or the negative electrode is dropped on the core material 410, a conductive material may be used.

  Here, the core material 410 includes a central portion 411 at a central position and end portions 412 at both ends of the central portion 411. Hereinafter, the configuration of the core material 410 will be described in detail.

  FIG. 3 is a perspective view showing the configuration of the core material 410 according to the embodiment of the present invention. In the following, the longitudinal direction (same as the section taken along the YZ plane in the figure) perpendicular to the winding axis (axis in the X-axis direction in the figure) when the electrode part 420 is wound is shown. The Z-axis direction in the figure is referred to as the longitudinal direction of the core material 410. Further, a short direction (cross-section when cut along the YZ plane in the figure) perpendicular to the winding axis (axis in the X-axis direction in the figure) when the electrode section 420 is wound (in the figure) (Y-axis direction) is referred to as the short direction of the core material 410.

  As shown in the figure, the core material 410 is a hollow flat plate-like member extending in the X-axis direction, and includes a central portion 411 at the central portion in the longitudinal direction (Z-axis direction), and in the longitudinal direction (Z-axis direction). End portions 412 are provided at both ends.

  The central part 411 is a part where the outer periphery and the inner periphery are formed as flat surfaces. Specifically, the central portion 411 is composed of two plate-like members arranged with a space in the Y-axis direction. Further, the end portion 412 is a plate-like portion whose outer periphery and inner periphery are formed with curved surfaces. Specifically, the end 412 has an arc-shaped outer shape in a cross-sectional shape on the YZ plane, and an elliptical space is formed inside. Thus, the core material 410 is made of a plate-like member, and has a shape such that the plate-like member is wound once.

  The plate-like member of the core material 410 is formed so that the end portion 412 is thinner in the lateral direction (Y-axis direction) than the central portion 411. For example, the thickness of the two plate-like members in the central portion 411 is 0.1 to 2 mm, and the thickness of the end portion 412 is 0.05 to 0.5 mm. In addition, the thickness of the center part 411 and the edge part 412 is not limited to the said numerical value.

  Further, the core material 410 has a space in which the end portion 412 has a width in the short side direction larger than that of the central portion 411. In the same figure, the central portion 411 has a space whose section in the YZ plane is rectangular, and the end portion 412 has a space whose section in the YZ plane is elliptical. Is not limited to this. For example, the space formed in the end 412 may have a polygonal shape such as a circular shape or a rectangular shape in cross section on the YZ plane.

  With the above configuration, the core material 410 is formed so that the end portion 412 has a smaller space occupancy rate than the central portion 411 in a state where the positive electrode, the negative electrode, and the separator are not wound. Here, the space occupancy indicates the ratio of the length occupied by the core material 410 to the width of the core material 410 in the short direction (Y-axis direction).

  Thus, the core material 410 is formed such that the end portion 412 has lower rigidity than the central portion 411.

  Next, the winding shaft inserted into the core material 410 when the positive electrode, the negative electrode, and the separator are wound around the core material 410 to form the electrode body 400 will be described.

  FIG. 4 is a perspective view showing the configuration of the winding shaft 20 according to the embodiment of the present invention. In the following, similarly to the core material 410, a cross section perpendicular to the winding axis (axis in the X-axis direction in the figure) when the electrode part 420 is wound (when cut along the YZ plane in the figure) The longitudinal direction (cross-sectional direction) in the cross section) is referred to as the longitudinal direction of the winding shaft 20. Further, a short direction (cross-section when cut along the YZ plane in the figure) perpendicular to the winding axis (axis in the X-axis direction in the figure) when the electrode section 420 is wound (in the figure) (Y-axis direction) is referred to as the short direction of the winding shaft 20.

  The winding shaft 20 is inserted into the core material 410 and is a shaft body for forming the electrode body 400 by winding the positive electrode, the negative electrode, and the separator around the winding axis (X-axis direction axis). As shown in the figure, the winding shaft 20 is a plate-like member extending in the X-axis direction, and has a central portion 21 at the central portion in the longitudinal direction (Z-axis direction), and both end portions in the longitudinal direction (Z-axis direction). The end portion 22 is provided.

  The central portion 21 is a flat plate portion having a flat outer periphery, and the outer surface shape corresponds to the inner surface shape of the central portion 411 of the core material 410. Further, the end 22 is a portion where the outer periphery is formed of a curved surface, and the outer surface shape corresponds to the inner surface shape of the end 412 of the core material 410. Specifically, the end 412 has an elliptical outer shape in the cross-sectional shape on the YZ plane. The shapes of the central portion 21 and the end portion 412 may be any shapes as long as they correspond to the inner surface shapes of the central portion 411 and the end portion 412 of the core material 410. Moreover, the whole winding shaft 20 does not need to correspond to the inner surface shape of the core material 410, and there may be a part having a gap. Furthermore, the length of the core material 410 and the winding shaft 20 may be different in the X-axis direction. For example, when attaching the winding shaft 20 to a winding device or the like, it is preferable that the portion protruding outward from the core material 410 has a simple shape such as a rectangle or a circle rather than corresponding to the shape of the inner surface.

  Thus, the winding shaft 20 is formed such that the end portion 22 has a width in the short side direction (Y-axis direction) larger than that of the central portion 21. The material of the winding shaft 20 is not particularly limited, and may be made of resin or metal.

  Next, a method for manufacturing the electrode body 400 will be described.

  FIG. 5 is a diagram for explaining a method of manufacturing the electrode body 400 according to the embodiment of the present invention.

  As shown in FIGS. 5A and 5B, the winding shaft 20 is inserted into the space inside the core material 410. And as shown to (c) and (d) of the figure, when the winding shaft 20 rotates, a positive electrode, a negative electrode, and a separator are wound around the core material 410, and the electrode body 400 is formed. . Then, after the electrode body 400 is formed, the winding shaft 20 is pulled out.

  Thus, the formed electrode body 400 is accommodated inside the container 100.

  FIG. 6 is a view showing a state in which the electrode body 400 according to the embodiment of the present invention is housed inside the container 100.

  As shown in the figure, the core material 410 is formed such that the end portion 412 has lower rigidity than the central portion 411. Therefore, the end portion 412 is deformed and the stress F1 received from the container 100 is reduced. To reduce. Thereby, the stress F1 received from the container 100 can be close to the stress F2, or the stress F1 can be made smaller than the stress F2.

  As described above, according to the electric storage element 10 according to the embodiment of the present invention, the end portion in the longitudinal direction in the cross section perpendicular to the winding axis is more rigid than the center portion on the innermost periphery of the electrode body 400. Is provided with a low core material 410. That is, the core material 410 is formed so that the end portion in the longitudinal direction has a smaller space occupancy rate than the center portion in a state before winding. Further, the core member 410 is formed of a plate-like member, and the plate-like member is formed so that the end portion in the longitudinal direction is thinner than the center portion. Further, the core material 410 has a space in which the end portion in the longitudinal direction is wider than the center portion. Therefore, when the electrode body 400 is inserted into the container 100 because the electrode body is deformed so that the width A of the end portion of the electrode body shown in FIG. 9B approaches the length of the width B of the center portion. The uniformity of the insertion coefficient can be improved, and the uniformity of the stress that the electrode body 400 receives from the container 100 can be improved. Thereby, since durability of the electrode body 400 can be improved, the performance of the electrical storage element 10 can be improved.

  Similarly, according to the winding shaft 20 according to the embodiment of the present invention, the end in the longitudinal direction in the cross section perpendicular to the winding axis is shorter in the cross section perpendicular to the winding axis than the center. It is formed so that the width in the hand direction is large. That is, the end portion of the winding shaft 20 has a width larger than that of the center portion, so that a space having a width greater at the end portion than that of the center portion is formed in the innermost periphery of the electrode body 400. As a result, an electrode body can be formed that is deformed so that the width A of the end portion of the electrode body shown in FIG. 9B approaches the length of the width B of the center portion. For this reason, the uniformity of the insertion coefficient when the electrode body 400 is inserted into the container 100 can be improved, and the uniformity of the stress that the electrode body 400 receives from the container 100 can be improved.

(Modification 1)
Next, Modification 1 of the present embodiment will be described. FIG. 7 is a perspective view showing the configuration of the core material 410a according to the first modification of the embodiment of the present invention.

  As shown in the figure, the core material 410a includes a central portion 411a at a central portion in the longitudinal direction (Z-axis direction) and end portions 412a at both ends in the longitudinal direction (Z-axis direction). Here, in the first modification, the outer periphery of the central portion 411a is formed with a curved surface protruding outward, which is different from the core material 410 of the above embodiment. Since other configurations are the same as the configurations in the above-described embodiment, the description thereof is omitted.

  As described above, the core member 410a according to the first modification is formed so that the central portion 411a is thicker than the end portion 412a, and thus the end portion 412a is further further than the central portion 411a. Stiffness is reduced. For this reason, the uniformity of the insertion coefficient when the electrode body is inserted into the container can be further improved, and the uniformity of the stress that the electrode body receives from the container can be further improved.

(Modification 2)
Next, a second modification of the present embodiment will be described. FIG. 8 is a perspective view showing a configuration of a core material 410b according to Modification 2 of the embodiment of the present invention.

  As shown in the figure, the core material 410b includes a central portion 411b at a central portion in the longitudinal direction (Z-axis direction) and end portions 412b at both ends in the longitudinal direction (Z-axis direction). Here, in the second modification, the central portion 411a and the end portion 412b have the same thickness, but the end portion 412a is formed of a material having lower rigidity than the central portion 411a. Since other configurations are the same as the configurations in the above-described embodiment, the description thereof is omitted.

  Thus, since the core part 410b which concerns on this modification 2 is shape | molded by the material whose end part 412a has lower rigidity than the center part 411a, the end part 412a is still more rigid than the center part 411a. Becomes lower. For this reason, the uniformity of the insertion coefficient when the electrode body is inserted into the container can be improved, and the uniformity of the stress that the electrode body receives from the container can be improved.

  The power storage element and the winding shaft according to the embodiment of the present invention and the modifications thereof have been described above, but the present invention is not limited to this embodiment and the modifications thereof.

  In other words, it should be considered that the embodiment and its modification disclosed this time are illustrative and not restrictive in all respects. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  Moreover, the form constructed | assembled combining the said embodiment and the said modification arbitrarily is also contained in the scope of the present invention. For example, the space formed in the core material 410a in Modification 1 may have the same shape as the space formed in the core material 410b in Modification 2. Further, the central portion 411b of the core material 410b in Modification 2 may have the same shape as the central portion 411a of the core material 410a in Modification 1.

  In addition, the present invention can be realized not only as such a power storage element 10 but also as an electrode body 400 included in the power storage element 10 or a core material 410 included in the electrode body 400.

  INDUSTRIAL APPLICABILITY The present invention can be applied to a power storage element that can improve the uniformity of stress that an electrode body receives from a container.

DESCRIPTION OF SYMBOLS 10 Power storage element 20 Winding axis 21 Central part 22 End part 100 Container 110 Cover plate 120 Positive electrode current collector 130 Negative electrode current collector 200 Positive electrode terminal 300 Negative electrode terminal 400 Electrode body 410, 410a, 410b Core material 411, 411a, 411b Central part 412, 412a, 412b End 420 Electrode

Claims (4)

A storage element comprising an electrode body formed by winding a positive electrode, a negative electrode, and a separator around a winding axis,
The electrode body includes a core material disposed on the innermost inner periphery of the wound positive electrode, the negative electrode, and the separator,
The power storage element, wherein the core material is formed of a material whose end portion in a longitudinal direction in a cross section perpendicular to the winding axis is lower in rigidity than a central portion. The electricity storage device according to claim 1, wherein the core material is formed integrally with the central portion having a linear shape in a cross section perpendicular to the winding axis and the end portion including the arc shape. An electrode body that is provided in a storage element and is formed by winding a positive electrode, a negative electrode, and a separator around a winding axis,
A core material disposed on the innermost inner periphery of the wound positive electrode, the negative electrode, and the separator;
The core member is formed of a material whose end portion in the longitudinal direction in a cross section perpendicular to the winding axis is lower in rigidity than the central portion. A core material disposed inside the innermost circumference of the wound positive electrode, negative electrode, and separator of an electrode body formed by winding a positive electrode, a negative electrode, and a separator around a winding axis. And
The core material is formed of a material whose end portion in the longitudinal direction in a cross section perpendicular to the winding axis is lower in rigidity than the center portion.

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