Energy storage cell and manufacturing method thereof

Abstract

To relieve stress concentration.SOLUTION: A power storage cell includes a cell case and a wound electrode body. The cell case is cylindrical. The cell case houses the wound electrode body. The wound electrode body includes a first electrode, separators, a second electrode, and a fixing member. The first electrode includes a first foil. The second electrode includes a second foil. In a winding direction of the wound electrode body, the first electrode has a first end portion. The second electrode has a second end portion. The separator has a third end portion. In the winding direction, the second end portion is located within a range from the first end portion to the third end portion. The first end portion is made of the first foil. The second end portion is made of the second foil. The fixing member fixes the wound electrode body at the third end portion. The fixing member satisfies a relationship of the formula "0.9×T2≤Tf≤1.1×(T1+T2)", where: T1 represents a thickness of the first foil; T2 represents a thickness of the second foil; Tf represents a maximum thickness of the fixing member.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to an energy storage cell and a method for manufacturing the same. [Background technology]

[0002] WO 2019 / 111742 discloses a tape for fixing the end of a wound electrode body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 111742 Summary of the Invention [Problem to be solved by the invention]

[0004] The energy storage cell may include a cylindrical case and a wound electrode assembly. The cylindrical case houses the wound electrode assembly. In a cross section perpendicular to the axial direction of the cylindrical case, the inner wall of the cylindrical case is circular. In the same cross section, the outline of the wound electrode assembly is also approximately circular. However, the wound electrode assembly has a lower circularity than the cylindrical case. Stress is generated by contact between the inner wall of the cylindrical case and the wound electrode assembly. The low circularity of the wound electrode assembly may cause stress concentration.

[0005] The purpose of the present disclosure is to reduce stress concentrations. [Means for solving the problem]

[0006] The technical configuration and effects of the present disclosure will be described below. However, the mechanism of action includes speculation. The mechanism of action does not limit the technical scope of the present disclosure.

[0007] 1. A storage cell according to one aspect of the present disclosure includes the following configuration. The energy storage cell includes a cell case and a wound electrode body. The cell case is cylindrical. The cell case houses the wound electrode body. The wound electrode body includes a first electrode, a separator, a second electrode, and a fixing member. The first electrode includes a first foil. The second electrode includes a second foil. In the winding direction of the wound electrode body, the first electrode has a first end portion. The second electrode has a second end portion. The separator has a third end portion. In the winding direction, the second end portion is located within the range from the first end portion to the third end portion. The first end portion is made of the first foil. The second end portion is made of the second foil. The fixing member fixes the wound electrode body at the third end portion. The fixing member satisfies the following relationship. 0.9×T2≦Tf≦1.1×(T1+T2) In the above formula, T1 represents the thickness of the first foil, T2 represents the thickness of the second foil, and Tf represents the maximum thickness of the fixing member.

[0008] In the wound electrode body, the first end portion is the end of the first electrode. The first end portion is made of the first foil. The second end portion is the end of the second electrode. The second end portion is made of the second foil. Hereinafter, "electrode foil" is a general term for the first foil and the second foil. In the winding direction, at least a portion of the fixing member is disposed outside the first end portion and the second end portion. At the end of the winding of the wound electrode body, the thickness of the electrode foil and the fixing member may form a step. It is believed that the formation of a large step reduces the roundness of the wound electrode body.

[0009] For example, when the second terminal end is close to the first terminal end, the magnitude of the step may vary depending on the relationship between the total thickness (T1 + T2) of the first and second foils and the maximum thickness (Tf) of the fixing member. Conventionally, the maximum thickness (Tf) of the fixing member is sufficiently larger than the total thickness (T1 + T2). In one aspect of the present disclosure, the maximum thickness of the fixing member is equal to or less than the total thickness of the first and second foils. That is, the maximum thickness (Tf) of the fixing member is 1.1 × (T1 + T2) or less. By making the maximum thickness of the fixing member equal to or less than the total thickness of the first and second foils, the step is expected to be reduced. The reduction of the step is expected to improve roundness.

[0010] For example, when the second terminal end is spaced apart from the first terminal end, the magnitude of the step may vary depending on the relationship between the thickness (T2) of the second foil and the maximum thickness (Tf) of the fixing member. In one aspect of the present disclosure, the maximum thickness of the fixing member is equal to or greater than the thickness of the second foil. That is, the maximum thickness (Tf) of the fixing member is 0.9 x T2 or greater. By making the maximum thickness of the fixing member equal to or greater than the thickness of the second foil, the step is expected to be reduced. The reduction in the step is expected to improve roundness. In one aspect of the present disclosure, the improvement in roundness is expected to alleviate stress concentration.

[0011] The "maximum thickness" refers to the thickness of the thickest part of the fixing member. The thickness of the fixing member may be constant or may vary. When the thickness of the fixing member is constant, the fixing member is said to have the maximum thickness throughout its entire area.

[0012] "Within the range" includes both ends of the range. That is, "an embodiment in which the second end portion is located within the range from the first end portion to the third end portion in the winding direction" also includes "an embodiment in which the position of the second end portion coincides with the position of the first end portion in the winding direction" and "an embodiment in which the position of the second end portion coincides with the position of the third end portion in the winding direction."

[0013] 2. The storage cell described in "1" above may include, for example, the following configuration. The fixing member further satisfies the following relationship: 0.9×T2≦Tf≦1.1×T2

[0014] For example, when the second end portion is spaced apart from the first end portion, the maximum thickness (Tf) of the fixing member may be set to be approximately the same as the thickness (T2) of the second foil, thereby reducing the step. For example, the maximum thickness (Tf) of the fixing member may be 0.9 to 1.1 times the thickness (T2) of the second foil.

[0015] 3. The storage cell described in "2" above may include, for example, the following configuration. In a cross section perpendicular to the winding axis of the wound electrode body, the angle formed by the first ray and the second ray is greater than 30°. The endpoints of the first ray and the second ray are the winding center. The first ray passes through the first end portion. The second ray passes through the second end portion.

[0016] When the angle described in "3" above exceeds 30°, the maximum thickness of the fixing member approaches the thickness of the second foil, and the step is expected to be reduced.

[0017] 4. The storage cell described in "1" above may include, for example, the following configuration. The fixing member further satisfies the following relationship: 0.9×(T1+T2)≦Tf≦1.1×(T1+T2)

[0018] For example, when the second end portion is close to the first end portion, the maximum thickness (Tf) of the fixing member is expected to be close to the total thickness (T1 + T2) of the first and second foils, thereby reducing the step. For example, the thickness (Tf) of the fixing member may be 0.9 to 1.1 times the total thickness (T1 + T2).

[0019] 5. The storage cell described in "4" above may include, for example, the following configuration. In a cross section perpendicular to the winding axis of the wound electrode body, the angle formed by the first ray and the second ray is 30° or less. The endpoints of the first ray and the second ray are the winding center. The first ray passes through the first end portion. The second ray passes through the second end portion.

[0020] When the angle described in "5" above is 30° or less, the maximum thickness of the fixing member is close to the total thickness of the first foil and the second foil, and thus the step is expected to be reduced.

[0021] 6. The storage cell according to any one of the above items "1" to "5" may include, for example, the following configuration. The fixing member has a first end and a second end. In the winding direction, the first end is a start end of the fixing member. In the winding direction, the second end is located opposite the first end. At the first end, the fixing member has a maximum thickness.

[0022] The starting end of the fixing member may be close to the electrode foil in the winding direction. The fixing member has the maximum thickness at the starting end, which is expected to reduce the step.

[0023] 7. The storage cell described in "6" above may include, for example, the following configuration. In at least a portion between the first end and the second end, the thickness of the fixing member decreases from the first end toward the second end.

[0024] Hereinafter, the aspect described in “7” above will also be referred to as “inclined.” By providing an inclination to the fixing member, for example, improvement in roundness is expected.

[0025] 8. The storage cell according to any one of the above items "1" to "7" may include, for example, the following configuration. The first electrode is a positive electrode, and the second electrode is a negative electrode.

[0026] 9. A method for producing a storage cell according to one aspect of the present disclosure includes the following steps (a) and (b): (a) Form a wound electrode body. (b) The wound electrode body is housed in a cell case to produce a storage cell. The cell case is cylindrical. The wound electrode body includes a first electrode, a separator, a second electrode, and a fixing member. The first electrode includes a first foil. The second electrode includes a second foil. In the winding direction of the wound electrode body, the first electrode has a first end portion. The second electrode has a second end portion. The separator has a third end portion. In the winding direction, the second end portion is located within the range from the first end portion to the third end portion. The first end portion is made of the first foil. The second end portion is made of the second foil. The fixing member fixes the wound electrode body at the third end portion. The fixing member satisfies the following relationship. 0.9×T2≦Tf≦1.1×(T1+T2) In the above formula, T1 represents the thickness of the first foil, T2 represents the thickness of the second foil, and Tf represents the maximum thickness of the fixing member.

[0027] 10. The method for manufacturing a storage cell described in "9" above may include, for example, the following configuration. The fixing member further satisfies the following relationship: 0.9×T2≦Tf≦1.1×T2

[0028] 11. The method for manufacturing a storage cell described in "9" above may include, for example, the following configuration. The fixing member further satisfies the following relationship: 0.9×(T1+T2)≦Tf≦1.1×(T1+T2)

[0029] 12. The method for manufacturing a storage cell according to any one of the above items "9" to "11" may include, for example, the following configuration. The wound electrode body is fixed by attaching a fixing member to the third terminal end portion. The fixing member has a first end and a second end. In the winding direction, the first end is a starting end of the fixing member. In the winding direction, the second end is located on the opposite side of the first end. The fixing member is attached from the first end side. For at least a period from the start to the end of attachment of the fixing member, tension applied to the fixing member increases.

[0030] For example, a tilt may be imparted to the fixing member due to a change in tension during application.

[0031] 13. The method for manufacturing a storage cell according to any one of the above items "9" to "12" may include, for example, the following configuration. The first electrode is a positive electrode, and the second electrode is a negative electrode.

[0032] Hereinafter, an embodiment of the present disclosure (hereinafter may be abbreviated as "the present embodiment") will be described. However, the present embodiment does not limit the technical scope of the present disclosure. The present embodiment is illustrative in all respects. The present embodiment is non-restrictive. The technical scope of the present disclosure encompasses all modifications within the meaning and scope equivalent to the claims. For example, it is also intended from the beginning that any configuration may be extracted from the present embodiment and arbitrarily combined. [Brief explanation of the drawings]

[0033] [Figure 1] 1 is a first schematic cross-sectional view showing an example of a storage cell according to the present embodiment. [Figure 2] FIG. 2 is a second schematic cross-sectional view showing an example of a storage cell according to the present embodiment. [Figure 3] FIG. 3 is a schematic cross-sectional view showing a first example of a winding end portion in the present embodiment. [Figure 4] FIG. 10 is a schematic cross-sectional view showing a second example of a winding end portion in the present embodiment. [Figure 5] FIG. 10 is a schematic cross-sectional view showing a third example of a winding end portion in the present embodiment. [Figure 6] FIG. 10 is a schematic cross-sectional view showing a fourth example of a winding end portion in the present embodiment. [Figure 7] FIG. 10 is a schematic cross-sectional view showing a fifth example of a winding end portion in this embodiment. [Figure 8] FIG. 10 is a schematic cross-sectional view showing a sixth example of the winding end portion in this embodiment. [Figure 9] FIG. 2 is a schematic cross-sectional view showing an example of a fixing member according to the present embodiment. [Figure 10] 3 is a schematic flowchart of a method for manufacturing a storage cell according to the present embodiment. [Figure 11] 10 is a graph showing an example of a change in tension in the present embodiment. [Figure 12] FIG. 2 is a schematic cross-sectional view showing an example of a cutting position of an electrode raw sheet. DETAILED DESCRIPTION OF THE INVENTION

[0034] 1. Explanation of terms "Comprise," "include," "have," and variations thereof are open-ended terms. Open-ended terms may or may not include additional elements in addition to the required elements. "Consisting of" is a closed term. However, even a configuration expressed in closed terminology may include additional elements that are normally associated impurities or that are unrelated to the disclosed technology. "Consisting essentially of..." is a semi-closed term. Semi-closed terminology allows for the addition of elements that do not substantially affect the basic and novel characteristics of the disclosed technology.

[0035] Expressions such as "may" and "may" are used in the permissive sense, meaning "to have the possibility," rather than in the obligatory sense, meaning "to have to."

[0036] Geometric terms should not be interpreted in a strict sense. Examples of geometric terms include "parallel," "perpendicular," and "orthogonal." For example, "parallel" may deviate slightly from the strict meaning of "parallel." Geometric terms may include, for example, tolerances, errors, etc. in design, work, manufacturing, etc. The dimensional relationships in each figure may not match the actual dimensional relationships. To aid the reader's understanding, the dimensional relationships in each figure may be changed. For example, length, width, thickness, etc. may be changed. Furthermore, some configurations may be omitted.

[0037] Numerical ranges such as "m to n%" are inclusive unless otherwise specified. That is, "m to n%" indicates a numerical range of "m% or more and n% or less." "m% or more and n% or less" includes "more than m% and less than n%." "Equal to or more" and "equal to or less" are represented by an inequality sign "≦." "More than" and "less than" are represented by an inequality sign "<" without an equality sign. A numerical value arbitrarily selected from within a numerical range may be used as a new upper or lower limit. For example, a new numerical range may be set by arbitrarily combining a numerical value within a numerical range with a numerical value described elsewhere in this specification, in a table, a figure, or the like.

[0038] All numerical values ​​are modified by the term "about." The term "about" may mean, for example, ±5%, ±3%, ±1%, etc. All numerical values ​​may be approximate values ​​that may vary depending on the application of the disclosed technology. All numerical values ​​may be expressed with significant figures. Unless otherwise specified, measured values ​​may be average values ​​of multiple measurements. The number of measurements may be three or more, five or more, or ten or more. In general, the more measurements are made, the more reliable the average value is expected to be. Measured values ​​may be rounded to the nearest significant figure. Measured values ​​may include errors, such as those associated with the detection limits of the measuring device.

[0039] 2. Energy storage cells FIG. 1 is a first schematic cross-sectional view showing an example of an energy storage cell according to this embodiment. The energy storage cell 1 is cylindrical. The energy storage cell 1 can be used for any purpose. For example, the energy storage cell 1 may be used as a power source for a vehicle. The energy storage cell 1 includes a cell case 200 and a wound electrode body 100. The energy storage cell 1 may further include, for example, an electrolyte (not shown), an external terminal 300, a first current collector plate 410, a second current collector plate 420, and an insulating member 500.

[0040] 2-1. Wound electrode body FIG. 1 shows a cross section parallel to the winding axis. The winding axis is a straight line formed by a set of winding centers 100c in the axial direction. The "axial direction" is direction A in FIG. 1. The wound electrode body 100 includes a first electrode 110, a separator 130, a second electrode 120, and a fixing member 140. The second electrode 120 has a polarity different from that of the first electrode 110. The first electrode 110 may be, for example, a positive electrode. The second electrode 120 may be, for example, a negative electrode. The first electrode 110 may be, for example, a negative electrode. The second electrode 120 may be, for example, a positive electrode.

[0041] The first electrode 110 and the second electrode 120 are all strip-shaped electrodes. The first electrode 110, the second electrode 120, and the separator 130 are all sheet-shaped. For example, the first electrode 110, the separator 130, and the second electrode 120 may be stacked in this order to form a laminate. The wound electrode body 100 may be formed by spirally winding the laminate.

[0042] The first electrode 110 includes a first foil 112 and a first active material layer 114. The first foil 112 can function as a current collector. The first foil 112 may include, for example, Al, Cu, Ni, Fe, Ti, etc. The first foil 112 includes a first region 112a and a second region 112b. The first active material layer 114 is disposed in the first region 112a. The first active material layer 114 includes a positive electrode active material or a negative electrode active material. The positive electrode active material may include, for example, a lithium-nickel composite oxide, etc. The negative electrode active material may include, for example, graphite, Si, SiO, etc. The second region 112b is adjacent to the first region 112a. The second region 112b is disposed at an end in the axial direction. The second region 112b has multiple tabs. The multiple tabs are separated in the circumferential direction of the wound electrode body 100. For example, multiple tabs may be welded to the second region 112b. For example, a portion of the second region 112b may be machined into a tab. Each tab leans inward in the radial direction. The "radial direction" is the R direction in FIG. 1, etc. The outer surface of each tab forms a substantially flat surface. Each tab is connected to the first current collector plate 410. Each tab may be welded to the first current collector plate 410.

[0043] The second electrode 120 includes a second foil 122 and a second active material layer 124. The second foil 122 can function as a current collector. The second foil 122 may include, for example, Al, Cu, Ni, Fe, or Ti. The second foil 122 includes a first region 122a and a second region 122b. The second active material layer 124 is disposed in the first region 122a. The second active material layer 124 includes a positive electrode active material or a negative electrode active material. The second region 122b is adjacent to the first region 122a. The second region 122b is disposed at an end in the axial direction. The second region 122b has multiple tabs. The multiple tabs are separated in the circumferential direction of the wound electrode body 100. Each tab leans toward the inside in the radial direction. The outer surface of each tab forms a substantially flat surface. Each tab is connected to a second current collector plate 420. Each tab may be welded to the second current collector plate 420 .

[0044] The separator 130 is electrically insulating. The separator 130 electrically separates the first electrode 110 from the second electrode 120. The separator 130 is disposed between the first electrode 110 and the second electrode 120 in the radial direction. The separator 130 is porous. The electrolyte can permeate the separator 130. The separator 130 may include, for example, a porous resin membrane. The electrolyte may include, for example, a lithium salt and an organic solvent.

[0045] 2-2. Fixing member FIG. 2 is a second schematic cross-sectional view showing an example of a storage cell according to this embodiment. FIG. 2 shows a cross section perpendicular to the winding axis. The "winding direction" is the W direction in FIG. 2. In the winding direction, the first electrode 110 has a first end portion 110e. The first end portion 110e is the end of the winding of the first electrode 110. The second electrode 120 has a second end portion 120e. The second end portion 120e is the end of the winding of the second electrode 120. The separator 130 has a third end portion 130e. The third end portion 130e is the end of the winding of the separator 130. In the winding direction, the second end portion 120e is located within the range from the first end portion 110e to the third end portion 130e. At the first end portion 110e, the first foil 112 is exposed from the first active material layer 114. The first foil 112 alone forms the first terminal end portion 110e. That is, the first terminal end portion 110e is made up of the first foil 112. In the second terminal end portion 120e, the second foil 122 is exposed from the second active material layer 124. The second foil 122 alone forms the second terminal end portion 120e. That is, the second terminal end portion 120e is made up of the second foil 122.

[0046] FIG. 12 is a schematic cross-sectional view showing an example of a cutting position of the electrode raw sheet. For example, the first terminal end portion 110e may be substantially composed of the first foil 112. In an embodiment in which the first terminal end portion 110e is substantially composed of the first foil 112, a first small piece 114a may be disposed at the tip of the first terminal end portion 110e. The first small piece 114a is part of the first active material layer 114. For example, the first active material layer 114 may be intermittently formed on the surface of the first foil 112 in the length direction of the electrode raw sheet. The "length direction" is the L direction in FIG. 12. The length direction corresponds to the winding direction of the wound electrode body 100. The electrode raw sheet is cut to separate it into individual first electrodes 110. For example, from the perspective of material efficiency, the cutting position Cp may be set within the first active material layer 114. After cutting, the first small piece 114a may be disposed at the tip of the first terminal end portion 110e. The first small pieces 114a may be disposed on only one side of the first foil 112. The first small pieces 114a may be disposed on both sides of the first foil 112. The length of the first small pieces 114a may be, for example, 5 mm or less, 4 mm or less, 3 mm or less, 2 mm or less, or 1 mm or less. The length of the first small pieces 114a may be 0.001 mm or more, 0.01 mm or more, 0.05 mm or more, 0.1 mm or more, 0.5 mm or more, or 1 mm or more. The second terminal end portion 120e is similar to the first terminal end portion 110e. The second terminal end portion 120e may be substantially composed of the second foil 122. A second small piece (not shown) may be disposed at the tip of the second terminal end portion 120e. The second small piece is part of the second active material layer 124.

[0047] The fixing member 140 may include, for example, an adhesive tape. The fixing member 140 may be attached to, for example, the third terminal end 130e. The fixing member 140 prevents the wound electrode body 100 from unraveling and maintains its structure. That is, the fixing member 140 fixes the wound electrode body 100 at the third terminal end 130e.

[0048] (1) Maximum thickness FIG. 3 is a schematic cross-sectional view showing a first example of a winding end portion in this embodiment. In this first example, the second terminal end 120e is spaced apart from the first terminal end 110e. In this first example, the step can be reduced by adjusting the relationship between the thickness (T2) of the second foil 122 and the maximum thickness (Tf) of the fixing member 140. That is, the maximum thickness (Tf) is 0.9×T2 or greater. By setting the maximum thickness (Tf) to 0.9×T2 or greater, the step is expected to be reduced. For example, the maximum thickness (Tf) of the fixing member may be 1.1×T2 or less. For example, the maximum thickness (Tf) of the fixing member may be equal to the thickness (T2) of the second foil 122.

[0049] FIG. 4 is a schematic cross-sectional view showing a second example of the winding end portion in this embodiment. In the second example, the second terminal end 120e is closer to the first terminal end 110e than in the first example. In the second example, the step can be reduced due to the relationship between the total thickness (T1 + T2) of the first foil 112 and the second foil 122 and the maximum thickness (Tf) of the fixing member 140. That is, the maximum thickness (Tf) is 1.1 × (T1 + T2) or less. By making the maximum thickness (Tf) 1.1 × (T1 + T2) or less, the step is expected to be reduced. For example, the maximum thickness (Tf) may be 0.9 × (T1 + T2) or more. For example, the maximum thickness (Tf) may be equal to the total thickness (T1 + T2).

[0050] In a configuration in which the first small piece 114a is disposed at the tip of the first terminal end portion 110e (see FIG. 12), the sum of the thickness of the first foil 112 and the thickness of the first active material layer 114 is regarded as T1. In a configuration in which the second small piece is disposed at the tip of the second terminal end portion 120e, the sum of the thickness of the second foil 122 and the thickness of the second active material layer 124 is regarded as T2.

[0051] As the second terminal end 120e approaches the first terminal end 110e, the structure of the end of the spiral may transition from the first example (FIG. 3) to the second example (FIG. 4). During the transition process, the maximum thickness (Tf) is expected to be greater than or equal to 0.9×T2 and less than or equal to 1.1×(T1+T2), thereby reducing the step. Therefore, the fixing member 140 satisfies the following relationship: 0.9×T2≦Tf≦1.1×(T1+T2)

[0052] The fixing member 140 may, for example, satisfy the relationship of the following formula. T2≦Tf≦(T1+T2)

[0053] The fixing member 140 may, for example, satisfy the relationship of the following formula. 0.9×T2≦Tf≦1.1×T2

[0054] The fixing member 140 may, for example, satisfy the relationship of the following formula. 0.9×(T1+T2)≦Tf≦1.1×(T1+T2)

[0055] The fixing member 140 may, for example, satisfy the relationship of the following formula. 0.4×(T1+T2)≦Tf≦0.6×(T1+T2)

[0056] The fixing member 140 may, for example, satisfy the relationship of the following formula. 0.6×(T1+T2)≦Tf≦0.9×(T1+T2)

[0057] The fixing member 140 may, for example, satisfy the relationship of the following formula. 0.1×(T1+T2)≦Tf≦0.4×(T1+T2)

[0058] The thickness (T1) of the first foil 112 and the thickness (T2) of the second foil 122 may each independently be, for example, 5 to 100 μm, 5 to 50 μm, 5 to 30 μm, 5 to 20 μm, or 5 to 15 μm. The thicknesses of each member (T1, T2, Tf) can be measured, for example, by a constant pressure thickness gauge.

[0059] (2) Angle The separation between the second terminal end portion 120e and the first terminal end portion 110e can be evaluated, for example, by the first angle θ1 in FIG. 2. The first angle θ1 is the angle formed by the first ray L1 and the second ray L2. The first angle θ1 is a positive angle. The first ray L1 is the initial line, and the second ray L2 is the radius vector. A "positive angle" is an angle resulting from the rotation of the radius vector from the initial line in the winding direction from the initial end to the terminal end. The endpoints of the first ray L1 and the second ray L2 are the winding center 100c. The "winding center" indicates the geometric center of the figure formed by the outline of the wound electrode body 100. The first ray L1 passes through the first terminal end portion 110e. The second ray L2 passes through the second terminal end portion 120e.

[0060] The first angle θ1 may be, for example, greater than 30°. When the first angle θ1 is greater than 30°, the maximum thickness (Tf) of the fixing member 140 approximates the thickness (T2) of the second foil 122, and this is expected to reduce the step. The first angle θ1 may be, for example, 45° or greater, 60° or greater, 90° or greater, 120° or greater, 150° or greater, 180° or greater, 210° or greater, 240° or greater, 270° or greater, 300° or greater, or 330° or greater. The first angle θ1 may be, for example, 360° or less, 330° or less, 300° or less, 270° or less, 240° or less, 210° or less, 180° or less, 150° or less, 120° or less, 90° or less, 60° or less, or 45° or less.

[0061] The first angle θ1 may be, for example, 30° or less. When the first angle θ1 is 30° or less, the maximum thickness (Tf) of the fixing member 140 approximates the total thickness (T1 + T2) of the first foil 112 and the second foil 122, and a reduction in the step is expected. The first angle θ1 may be, for example, 25° or less, 20° or less, 15° or less, 10° or less, 5° or less, 3° or less, or 1° or less. The first angle θ1 may be, for example, 0° or more, 1° or more, 3° or more, 5° or more, 10° or more, 15° or more, 20° or more, or 25° or more.

[0062] When the first angle θ1 is 0°, the position of the second terminal end 120e coincides with the position of the first terminal end 110e in the winding direction.

[0063] The separation between the third terminal end portion 130e and the second terminal end portion 120e can be evaluated, for example, by the second angle θ2 in FIG. 2. The second angle θ2 is the angle formed by the second ray L2 and the third ray L3. The second angle θ2 is a positive angle. The second ray L2 is the initial line, and the third ray L3 is the radius vector. The end point of the third ray L3 is also the winding center 100c. The third ray L3 passes through the third terminal end portion 130e.

[0064] The second angle θ2 may be, for example, any of 0° or more, 1° or more, 3° or more, 5° or more, 10° or more, 15° or more, 30° or more, 45° or more, 60° or more, 90° or more, 120° or more, 150° or more, 180° or more, 210° or more, 240° or more, 270° or more, 300° or more, or 330° or more. The second angle θ2 may be, for example, any of 360° or less, 330° or less, 300° or less, 270° or less, 240° or less, 210° or less, 180° or less, 150° or less, 120° or less, 90° or less, 60° or less, 45° or less, 30° or less, 15° or less, 10° or less, 5° or less, 3° or less, or 1° or less.

[0065] When the second angle θ2 is 0°, the position of the second terminal end 120e coincides with the position of the third terminal end 130e in the winding direction.

[0066] (3) Placement The arrangement of the fixing member 140 is arbitrary as long as the third terminal end portion 130e can be fixed. For example, as shown in FIG. 3 etc., a portion of the fixing member 140 may overlap the third terminal end portion 130e. That is, in the radial direction, at least a portion of the fixing member 140 may be arranged outside the separator 130 (outermost layer). The "radial direction" is the R direction in FIG. 3 etc.

[0067] 5 is a schematic cross-sectional view showing a third example of the winding end portion in this embodiment. For example, at least a part of the fixing member 140 may be disposed inside the separator 130 (outermost layer) in the radial direction.

[0068] 6 is a schematic cross-sectional view showing a fourth example of the winding end portion in this embodiment. For example, at least a portion of the fixing member 140 may overlap the electrode foil. For example, at least a portion of the fixing member 140 may overlap the second foil 122. At least a portion of the fixing member 140 may overlap both the first foil 112 and the second foil 122.

[0069] 7 is a schematic cross-sectional view showing a fifth example of a winding end portion in this embodiment. For example, inside the outermost layer, the fixing member 140 may be adjacent to the electrode foil. For example, the fixing member 140 may be in contact with the second foil 122. There may be a gap between the fixing member 140 and the electrode foil. In the winding direction, the fixing member 140 does not have to extend beyond the third terminal end portion 130e.

[0070] (4) Inclination FIG. 8 is a schematic cross-sectional view showing a sixth example of a winding end portion in this embodiment. The fixing member 140 has a first end 140s and a second end 140e. In the winding direction, the first end 140s is the starting end of the fixing member 140. The second end 140e is the ending end of the fixing member 140. The second end 140e is located on the opposite side of the first end 140s. In the winding direction, the thickness of the fixing member 140 may be, for example, substantially constant. "Substantially constant" indicates that the ratio of the maximum value to the minimum value is between 1 and 1.2. The ratio of the maximum value to the minimum value may be, for example, between 1 and 1.1 or between 1 and 1.05. For example, the fixing member 140 may have a maximum thickness at the first end 140s. By having the fixing member 140 have a maximum thickness at the first end 140s, it is expected that steps will be reduced.

[0071] The fixing member 140 may have a slope. That is, in at least a portion between the first end 140s and the second end 140e, the thickness of the fixing member 140 may decrease from the first end 140s to the second end 140e. By having the fixing member 140 have a slope, it is expected that the roundness will be improved. The slope may extend over the entire fixing member 140. That is, the fixing member 140 may have a maximum thickness at the first end 140s. The fixing member 140 may have a minimum thickness at the second end 140e. The "minimum thickness" refers to the thickness of the thinnest portion of the fixing member 140.

[0072] The thickness of the fixing member 140 may vary continuously, for example. For example, the thickness of the fixing member 140 may decrease continuously from the first end 140s to the second end 140e. The thickness may decrease linearly, for example. The thickness may decrease monotonically, for example. The thickness may decrease nonlinearly, for example. The thickness may decrease stepwise, for example. The thickness may decay exponentially, for example.

[0073] (5) Base material layer, adhesive layer 9 is a schematic cross-sectional view showing an example of a fixing member in this embodiment. The fixing member 140 may have any configuration as long as it can fix the wound electrode body 100. The fixing member 140 may include, for example, a base material layer 141 and an adhesive layer 142. For example, the base material layer 141 may have a substantially constant thickness over the entire surface. At least a portion of the base material layer 141 may have a slope. The adhesive layer 142 may have a substantially constant thickness over the entire surface. At least a portion of the adhesive layer 142 may have a slope.

[0074] Fixing member 140 may be, for example, electrically insulating. Base material layer 141 may contain, for example, at least one material selected from the group consisting of polypropylene (PP), polyimide (PI), polyethylene (PE), polyethylene terephthalate (PET), and polyphenylene sulfide (PPS). Adhesive layer 142 may contain, for example, at least one material selected from the group consisting of an acrylic adhesive, a silicone adhesive, a urethane adhesive, and a rubber adhesive.

[0075] Fixing member 140 may be made of, for example, adhesive layer 142. Adhesive layer 142 may contain, for example, at least one selected from the group consisting of vinyl acetate resin emulsion adhesives, acrylic resin emulsion adhesives, vinyl acetate resin solvent adhesives, acrylic resin solvent adhesives, vinyl chloride resin solvent adhesives, chloroprene rubber solvent adhesives, chloroprene rubber solvent mastic adhesives, nitrile rubber solvent adhesives, urethane resin adhesives, epoxy resin adhesives, modified silicone resin adhesives, epoxy-modified silicone resin adhesives, starch adhesives, polymer cement mortar, epoxy resin mortar, and silylated urethane resin adhesives.

[0076] 2-3. Cell case The cell case 200 houses the wound electrode body 100. The cell case 200 may be made of, for example, metal. The cell case 200 may contain, for example, Fe, stainless steel, etc. The cell case 200 is cylindrical. The cell case 200 includes a peripheral wall 210, a top wall 220, and a bottom wall 230. The peripheral wall 210 is cylindrical. The peripheral wall 210 surrounds the outer peripheral surface of the wound electrode body 100. The peripheral wall 210 may be in contact with the outer peripheral surface of the wound electrode body 100.

[0077] The top wall 220 is connected to an end of the peripheral wall 210 in the axial direction. For example, a through-hole for connection to the external terminal 300 may be formed in the center of the top wall 220. The bottom wall 230 faces the top wall 220 in the axial direction. The bottom wall 230 is connected to an end of the peripheral wall 210 in the axial direction. The bottom wall 230 is in contact with the second current collector plate 420.

[0078] The external terminal 300 is disposed on the outer surface of the top wall 220. The external terminal 300 has a polarity different from that of the cell casing 200. The external terminal 300 may have, for example, a positive polarity. The cell casing 200 may have, for example, a negative polarity. The external terminal 300 may have, for example, a negative polarity. The cell casing 200 may have, for example, a positive polarity.

[0079] The insulating member 500 electrically separates the external terminal 300 from the cell casing 200. The insulating member 500 includes a first insulating portion 510 and a second insulating portion 520. The first insulating portion 510 is interposed between the external terminal 300 and the top wall 220. Inside the cell casing 200, the second insulating portion 520 is interposed between the first current collector plate 410 and the cell casing 200.

[0080] 3. Energy storage cell manufacturing method 10 is a schematic flowchart of a method for manufacturing a storage cell according to this embodiment. Hereinafter, the "method for manufacturing a storage cell according to this embodiment" may be abbreviated as "this manufacturing method." This manufacturing method includes "(a) winding" and "(b) case insertion."

[0081] 3-1.(a) Winding This manufacturing method includes forming a wound electrode body 100. Details of the wound electrode body 100 are as described above. A first electrode 110, a second electrode 120, a separator 130, and a fixing member 140 are prepared. One separator 130 may be used alone, or two or more separators 130 may be used. For example, a laminate may be formed by stacking four components, namely, the first electrode 110, the separator 130, the second electrode 120, and the separator 130. The wound electrode body 100 may be formed by spirally winding the laminate. The wound electrode body 100 can be fixed by attaching a fixing member 140 to the third terminal end portion 130e of the separator 130. The formation of the laminate and the winding of the laminate may be performed sequentially or simultaneously.

[0082] The manufacturing method may include, for example, imparting a slope to the fixing member 140. For example, the tension applied to the fixing member 140 may be changed during application of the fixing member 140.

[0083] 11 is a graph showing an example of tension change in this embodiment. At a first time point p1, attachment begins. At the first time point p1, a first end 140s of the fixing member 140 adheres to the separator 130. The fixing member 140 is gradually attached starting from the first end 140s side. At a second time point p2, a second end 140e of the fixing member 140 adheres to the separator 130. At the second time point p2, attachment is completed.

[0084] For example, the tension may be increased at least for a period between the first point in time p1 and the second point in time p2. The increase in tension may impart an inclination to the fixing member 140. For example, a first tension F1 is applied at the first point in time p1. A second tension F2 is applied at the second point in time p2. The second tension F2 is greater than the first tension F1. The ratio (F2 / F1) of the second tension F2 to the first tension F1 may be, for example, 1.1 or more, 1.2 or more, 1.5 or more, or 2 or more. The ratio (F2 / F1) may be, for example, 2 or less, 1.5 or less, 1.2 or less, or 1.1 or less. The increase in tension may be continuous, for example. For example, the tension may increase monotonically from the first point in time p1 to the second point in time p2. The increase in tension may be stepwise, for example. For example, the tension may increase stepwise from the first point in time p1 to the second point in time p2, or may increase exponentially from the first point in time p1 to the second point in time p2.

[0085] 3-2.(b) Inserting the case This manufacturing method includes manufacturing an energy storage cell 1 by housing a wound electrode body 100 in a cell case 200. The wound electrode body 100 is inserted into the cell case 200 so that the winding axis of the wound electrode body 100 is parallel to the axial direction of the cell case 200. The first electrode 110 is electrically connected to an external terminal 300. The second electrode 120 is electrically connected to the cell case 200. After the wound electrode body 100 is inserted, an electrolyte may be injected into the cell case 200. The cell case 200 is sealed to complete the energy storage cell 1. For example, the bottom wall 230 may be welded to the peripheral wall 210 by a laser or the like. [Explanation of symbols]

[0086] 1 Energy storage cell, 100 Wound electrode body, 100c Winding center, 110 First electrode, 110e First end portion, 112 First foil, 112a, 122a First region, 112b, 122b Second region, 114 First active material layer, 114a First small piece, 120 Second electrode, 120e Second end portion, 122 Second foil, 124 Second active material layer, 130 Separator, 130e Third end portion, 140 Fixing member, 140s First end portion, 140e Second end portion, 141 Base material layer, 142 Adhesive layer, 200 Cell case, 210 Peripheral wall, 220 Top wall, 230 Bottom wall, 300 External terminal, 410 First current collector plate, 420 Second current collector plate, 500 Insulating member, 510 First insulating part, 520 second insulating part, F1 first tension, F2 second tension, L1 first half line, L2 second half line, L3 third half line, p1 first point in time, p2 second point in time, θ1 first angle, θ2 second angle, Cp cutting position.

Claims

1. a cell case and a wound electrode body; the cell casing is cylindrical; the cell case accommodates the wound electrode body, the wound electrode body includes a first electrode, a separator, a second electrode, and a fixing member; the first electrode includes a first foil; the second electrode includes a second foil; In a winding direction of the wound electrode body, the first electrode has a first end portion, the second electrode has a second end portion, and the separator has a third end portion, In the winding direction, the second terminal end portion is located within a range from the first terminal end portion to the third terminal end portion, the first terminal end is made of the first foil; the second terminal end is made of the second foil; the fixing member fixes the wound electrode body at the third terminal end portion, The fixing member has the formula: 0.9×T2≦Tf≦1.1×(T1+T2) The relationship satisfies the formula: 0.9×T2≦Tf≦1.1×T2 Further fulfilling the relationship, In the above formula, T1 denotes the thickness of the first foil, T2 denotes the thickness of the second foil, and Tf indicates the maximum thickness of the fixing member, Energy storage cell.

2. In a cross section perpendicular to the winding axis of the wound electrode body, the angle between the first ray and the second ray is greater than 30°; end points of the first ray and the second ray are winding centers; the first ray passes through the first termination portion, and the second ray passes through the second end portion; The energy storage cell according to claim 1 .

3. The fixing member has the formula: 0.9×(T1+T2)≦Tf≦1.1×(T1+T2) Further satisfying the relationship, The energy storage cell according to claim 1 .

4. In a cross section perpendicular to the winding axis of the wound electrode body, the angle between the first ray and the second ray is 30° or less; end points of the first ray and the second ray are winding centers; the first ray passes through the first termination portion, and the second ray passes through the second end portion; The energy storage cell according to claim 3 .

5. the fixing member has a first end and a second end; In the winding direction, the first end is a starting end of the fixing member, the second end is located opposite the first end in the winding direction; and At the first end, the securing member has the maximum thickness. The energy storage cell according to any one of claims 1 to 4.

6. In at least a portion between the first end and the second end, the thickness of the fixing member decreases from the first end toward the second end. The energy storage cell according to claim 5 .

7. the first electrode is a positive electrode, and The second electrode is a negative electrode. The energy storage cell according to claim 1 .

8. (a) forming a wound electrode body; and (b) manufacturing an electricity storage cell by housing the wound electrode body in a cell case; Including, the cell casing is cylindrical; the wound electrode body includes a first electrode, a separator, a second electrode, and a fixing member; the first electrode includes a first foil; the second electrode includes a second foil; In a winding direction of the wound electrode body, the first electrode has a first end portion, the second electrode has a second end portion, and the separator has a third end portion, In the winding direction, the second terminal end portion is located within a range from the first terminal end portion to the third terminal end portion, the first terminal end is made of the first foil; the second terminal end is made of the second foil; the fixing member fixes the wound electrode body at the third terminal end portion, The fixing member has the formula: 0.9×T2≦Tf≦1.1×(T1+T2) The relationship satisfies the formula: 0.9×T2≦Tf≦1.1×T2 Further fulfilling the relationship, In the above formula, T1 denotes the thickness of the first foil, T2 denotes the thickness of the second foil, and Tf indicates the maximum thickness of the fixing member, A method for manufacturing a storage cell.

9. The fixing member has the formula: 0.9×(T1+T2)≦Tf≦1.1×(T1+T2) Further satisfying the relationship, The method for manufacturing the storage cell according to claim 8 .

10. The fixing member is attached to the third terminal end portion, thereby fixing the wound electrode body, the fixing member has a first end and a second end; In the winding direction, the first end is a starting end of the fixing member, The second end is located on the opposite side of the first end in the winding direction, the fixing member is attached from the first end side, and The tension applied to the fixing member increases at least for a period from the start of attachment to the end of attachment of the fixing member. The method for manufacturing the storage cell according to claim 8 or 9.

11. the first electrode is a positive electrode, and The second electrode is a negative electrode. The method for manufacturing the storage cell according to claim 8 .

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