Power storage cell and method for manufacturing same

Abstract

The invention discloses a power storage cell and a method for manufacturing the same. The electricity storage cell includes a cell case and a wound electrode body. And the unit shell is cylindrical. The unit 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. The first electrode has a first terminal portion in a winding direction of the wound electrode body. The second electrode has a second terminal portion. The separator has a third terminal portion. In the winding direction, the second terminal portion is located within a range from the first terminal portion to the third terminal portion. The first terminal part is composed of a first foil. The second terminal part is composed of a second foil. The fixing member fixes the wound electrode body to the third terminal portion. The fixing member satisfies the relationship of "0.9 * T2 < = Tf < = 1.1 * (T1 + T2)". T1 represents the thickness of the first foil. And T2 represents the thickness of the second foil. Tf represents the maximum thickness of the fixing member.

Description

Technical Field

[0001] The present disclosure relates to a power storage unit and a method for manufacturing the same. Background Art

[0002] International Publication No. 2019 / 111742 discloses a tape for fixing the winding end portion of a wound electrode body. Summary of the invention

[0003] The storage unit can include a cylindrical shell and a wound electrode body. The cylindrical shell accommodates the wound electrode body. In a cross section perpendicular to the axial direction of the cylindrical shell, the inner wall of the cylindrical shell is circular. In this cross section, the outline of the wound electrode body is also roughly circular. However, the wound electrode body has a lower roundness than the cylindrical shell. Stress is generated due to the contact between the inner wall of the cylindrical shell and the wound electrode body. Since the roundness of the wound electrode body is low, there is a possibility of stress concentration.

[0004] An object of the present disclosure is to alleviate stress concentration.

[0005] The following describes the technical structure and effects of the present disclosure. However, the mechanism of action includes assumptions. The mechanism of action does not limit the technical scope of the present disclosure.

[0006] 1. A power storage unit according to one aspect of the present disclosure includes the following configuration.

[0007] The storage cell includes a cell housing and a wound electrode body. The cell housing is cylindrical. The cell housing 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 the winding direction of the wound electrode body, the first electrode has a first terminal portion. The second electrode has a second terminal portion. The separator has a third terminal portion. In the winding direction, the second terminal portion is located within the range from the first terminal portion to the third terminal portion. The first terminal portion is composed of the first foil. The second terminal portion is composed of the second foil. The fixing member fixes the wound electrode body at the third terminal portion.

[0008] The fixing member satisfies the following relationship.

[0009] 0.9×T2≤Tf≤1.1×(T1+T2)

[0010] 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.

[0011] In the wound electrode body, the first terminal portion is the winding end portion of the first electrode. The first terminal portion is composed of the first foil. The second terminal portion is the winding end portion of the second electrode. The second terminal portion is composed 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 arranged on the outside of the first terminal portion and the second terminal portion. At the winding end portion of the wound electrode body, the thickness of the electrode foil and the fixing member can form a step difference. It can be considered that the roundness of the wound electrode body is reduced due to the formation of a large step difference.

[0012] For example, when the second terminal portion is close to the first terminal portion, the size of the step difference can vary according to the relationship between the total thickness (T1+T2) of the first foil and the second foil and the maximum thickness (Tf) of the fixing member. In the past, the maximum thickness (Tf) of the fixing member was sufficiently large compared to 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 foil and the second foil. That is, the maximum thickness (Tf) of the fixing member is less than 1.1×(T1+T2). By making the maximum thickness of the fixing member equal to or less than the total thickness of the first foil and the second foil, a reduction in the step difference can be expected. By reducing the step difference, an improvement in roundness can be expected.

[0013] For example, when the second terminal portion is away from the first terminal portion, the size of the step difference can vary according to 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 greater than 0.9×T2. By making the maximum thickness of the fixing member equal to or greater than the thickness of the second foil, a reduction in the step difference can be expected. By reducing the step difference, an improvement in roundness can be expected. In one aspect of the present disclosure, a relaxation of stress concentration can be expected by improving roundness.

[0014] Furthermore, the "maximum thickness" means the thickness of the thickest part of the fixing member. The thickness of the fixing member may be constant or variable. When the thickness of the fixing member is constant, the fixing member has the maximum thickness in the entire area.

[0015] “Within the range” includes both ends of the range. That is, “in the winding direction, the second terminal portion is located within the range from the first terminal portion to the third terminal portion” also includes “in the winding direction, the position of the second terminal portion coincides with the position of the first terminal portion” and “in the winding direction, the position of the second terminal portion coincides with the position of the third terminal portion”.

[0016] 2. The power storage unit described in the above “1” may include the following configuration, for example.

[0017] The fixing member also satisfies the following relationship.

[0018] 0.9×T2≤Tf≤1.1×T2

[0019] For example, when the second terminal portion is away from the first terminal portion, the maximum thickness (Tf) of the fixing member is close to the thickness (T2) of the second foil, and the step difference can be expected to be reduced. For example, the maximum thickness (Tf) of the fixing member can be 0.9 to 1.1 times the thickness (T2) of the second foil.

[0020] 3. The power storage unit described in the above “2” may include the following configuration, for example.

[0021] In a cross section perpendicular to the winding axis of the wound electrode body, the angle formed by the first half straight line and the second half straight line exceeds 30°. The endpoints of the first half straight line and the second half straight line are the winding center. The first half straight line passes through the first terminal portion. The second half straight line passes through the second terminal portion.

[0022] When the angle of the configuration described in the above “3” exceeds 30°, the maximum thickness of the fixing member is close to the thickness of the second foil, and thus a reduction in the step difference can be expected.

[0023] 4. The power storage unit described in the above “1” may include the following configuration, for example.

[0024] The fixing member also satisfies the following relationship.

[0025] 0.9×(T1+T2)≤Tf≤1.1×(T1+T2)

[0026] For example, when the second terminal portion is close to the first terminal portion, the maximum thickness (Tf) of the fixing member is close to the total thickness (T1+T2) of the first foil and the second foil, and the step difference can be expected to be reduced. For example, the thickness (Tf) of the fixing member can be 0.9 to 1.1 times the total thickness (T1+T2).

[0027] 5. The power storage unit described in the above “4” may include the following configuration, for example.

[0028] In a cross section perpendicular to the winding axis of the wound electrode body, the angle formed by the first half straight line and the second half straight line is 30° or less. The endpoints of the first half straight line and the second half straight line are the winding center. The first half straight line passes through the first terminal portion. The second half straight line passes through the second terminal portion.

[0029] When the angle of the configuration described in the above “5” is 30 degrees 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 a reduction in the step difference can be expected.

[0030] 6. The power storage unit described in any one of “1” to “5” above may include the following configuration, for example.

[0031] The fixing member has a first end and a second end. In the winding direction, the first end is the starting end of the fixing member. In the winding direction, the second end is located on the opposite side of the first end. At the first end, the fixing member has the maximum thickness.

[0032] In the winding direction, the starting end of the fixing member may be close to the electrode foil. Since the fixing member has the largest thickness at the starting end, it is expected that the step difference can be reduced.

[0033] 7. The power storage unit described in the above “6” may include the following configuration, for example.

[0034] In at least a portion between the first end portion and the second end portion, the thickness of the fixing member decreases as it goes from the first end portion toward the second end portion.

[0035] Hereinafter, the aspect described in the above “7” will also be referred to as “inclined.” By providing an inclination to the fixing member, for example, improvement in roundness can be expected.

[0036] 8. The power storage unit described in any one of “1” to “7” above may include the following configuration, for example.

[0037] The first electrode is a positive electrode and the second electrode is a negative electrode.

[0038] 9. A method for manufacturing a power storage unit according to one aspect of the present disclosure includes the following (a) and (b).

[0039] (a) Forming a wound electrode body.

[0040] (b) The electric storage cell is manufactured by housing the wound electrode body in a cell case.

[0041] The unit housing 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 terminal portion. The second electrode has a second terminal portion. The separator has a third terminal portion. In the winding direction, the second terminal portion is located within the range from the first terminal portion to the third terminal portion. The first terminal portion is composed of the first foil. The second terminal portion is composed of the second foil. The fixing member fixes the wound electrode body at the third terminal portion.

[0042] The fixing member satisfies the following relationship.

[0043] 0.9×T2≤Tf≤1.1×(T1+T2)

[0044] 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.

[0045] 10. The method for manufacturing the power storage unit described in the above-mentioned “9” may include the following configuration, for example.

[0046] The fixing member also satisfies the following relationship.

[0047] 0.9×T2≤Tf≤1.1×T2

[0048] 11. The method for manufacturing the power storage unit described in the above-mentioned “9” may include the following configuration, for example.

[0049] The fixing member also satisfies the following relationship.

[0050] 0.9×(T1+T2)≤Tf≤1.1×(T1+T2)

[0051] 12. The method for manufacturing the electric storage unit described in any one of “9” to “11” above may include the following configuration, for example.

[0052] The wound electrode body is fixed by attaching a fixing member to the third terminal portion. The fixing member has a first end and a second end. In the winding direction, the first end is the 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. In at least one period from the start of attachment of the fixing member to the end of attachment, the tension applied to the fixing member increases.

[0053] For example, the fixing member may be given an inclination by changing the tension during the attachment process.

[0054] 13. The method for manufacturing the electric storage unit described in any one of “9” to “12” above may include the following configuration, for example.

[0055] The first electrode is a positive electrode and the second electrode is a negative electrode.

[0056] The following describes an embodiment of the present disclosure (hereinafter referred to as "the present embodiment"). However, the present embodiment does not limit the technical scope of the present disclosure. The present embodiment is illustrative in all aspects. The present embodiment is non-restrictive. The technical scope of the present disclosure includes all changes within the meaning and scope equivalent to the description of the claims. For example, it was predetermined from the beginning to extract any configuration from the present embodiment and combine them arbitrarily.

[0057] The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 It is a first schematic cross-sectional view showing an example of the power storage unit in the present embodiment.

[0059] Figure 2 It is a second schematic cross-sectional view showing an example of the power storage unit in the present embodiment.

[0060] Figure 3 It is a schematic cross-sectional view showing a first example of the winding end portion in the present embodiment.

[0061] Figure 4 It is a schematic cross-sectional view showing a second example of the winding end portion in the present embodiment.

[0062] Figure 5 It is a schematic cross-sectional view showing a third example of the winding end portion in the present embodiment.

[0063] Figure 6 It is a schematic cross-sectional view showing a fourth example of the winding end portion in the present embodiment.

[0064] Figure 7 It is a schematic cross-sectional view showing a fifth example of the winding end portion in the present embodiment.

[0065] Figure 8 It is a schematic cross-sectional view showing a sixth example of the winding end portion in the present embodiment.

[0066] Fig. 9 It is a schematic cross-sectional view showing an example of a fixing member in this embodiment.

[0067] Fig.10 This is a schematic flowchart of the method for manufacturing the power storage unit in the present embodiment.

[0068] Fig.11 This is a graph showing an example of tension change in this embodiment.

[0069] Fig.12 It is a schematic cross-sectional view showing an example of a cutting position of an electrode raw sheet. DETAILED DESCRIPTION

[0070] 1. Explanation of terms

[0071] "Having", "including", "having" and their variations are open-ended terms. In addition to essential elements, open-ended terms may or may not include additional elements. A statement such as "consisting of..." is a closed-ended term. However, even a composition expressed in a closed-ended term may contain impurities that are usually incidental, or additional elements that are unrelated to the technology disclosed herein. A statement such as "consisting essentially of..." is a semi-closed term. In a semi-closed term, it is allowed to add elements that have no substantial effect on the basic and new characteristics of the technology disclosed herein.

[0072] The expressions “may be carried out” and “can be carried out” are not used in an obligatory sense, that is, “must be carried out”, but in a permissive sense, that is, “there is a possibility of carrying out…”.

[0073] Geometric terms should not be understood as strict meanings. As geometric terms, for example, "parallel", "perpendicular", "orthogonal", etc. can be exemplified. For example, "parallel" can slightly deviate from the strict meaning of "parallel". Geometric terms can include, for example, tolerances and errors in design, operation, and manufacturing. Sometimes the dimensional relationship in each figure is inconsistent with the actual dimensional relationship. In order to help the reader's understanding, the dimensional relationship in each figure is sometimes changed. For example, the length, width, thickness, etc. are sometimes changed. In addition, a part of the structure is sometimes omitted.

[0074] Numerical ranges such as “m to n%” include both ends unless otherwise specified. That is, “m to n%” means a numerical range of “above m% and below n%”. “Above m% and below n%” includes “more than m% and less than n%”. “Above” and “below” are represented by an inequality sign “≤” with an equal sign. “Exceeding” and “less than” are represented by an inequality sign “<” without an equal sign. A value arbitrarily selected from the numerical range can be used as a new upper limit or lower limit. For example, a new numerical range can be set by arbitrarily combining numerical values ​​within the numerical range with numerical values ​​recorded in other parts, tables, figures, etc. in this specification.

[0075] 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 how the disclosed technology is used. All numerical values ​​may be expressed in significant figures. Unless otherwise specified, the measured value may be an average value of multiple measurements. The number of measurements may be more than 3 times, more than 5 times, or more than 10 times. Generally, the more measurements are made, the higher the reliability of the average value can be expected. The measured value may be rounded off based on the number of significant figures. The measured value may include errors associated with, for example, the detection limit of the measuring device.

[0076] 2. Storage unit

[0077] Figure 1 1 is a schematic cross-sectional view showing an example of a storage cell in the present embodiment. The storage cell 1 is cylindrical. The storage cell 1 can be applied to any purpose. The storage cell 1 can be used, for example, as a power source for a vehicle. The storage cell 1 includes a cell housing 200 and a wound electrode body 100. The storage cell 1 may further include, for example, an electrolyte (not shown), an external terminal 300, a first collector plate 410, a second collector plate 420, and an insulating member 500.

[0078] 2-1. Wound electrode body

[0079] Figure 1 The cross section parallel to the winding axis is shown. The winding axis is a straight line formed by the collection of winding centers 100c in the axial direction. Figure 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.

[0080] The first electrode 110 and the second electrode 120 are both strip electrodes. The first electrode 110, the second electrode 120, and the separator 130 are all in sheet form. For example, a laminate can be formed by sequentially stacking the first electrode 110, the separator 130, and the second electrode 120. The wound electrode body 100 can be formed by winding the laminate into a spiral shape.

[0081] 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 arranged 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, 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 arranged at the end in the axial direction. The second region 112b has a plurality of tabs. The plurality of tabs are separated in the circumferential direction of the wound electrode body 100. For example, the plurality of tabs may be welded to the second region 112b. For example, a portion of the second region 112b may be processed into a tab. Each pole ear falls inward in the radial direction. Figure 1The outer surface of each electrode tab forms a substantially flat surface. Each electrode tab is connected to the first current collecting plate 410. Each electrode tab may be welded to the first current collecting plate 410.

[0082] 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, Ti, etc. 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 the end in the axial direction. The second region 122b has a plurality of tabs. The plurality of tabs are separated in the circumferential direction of the wound electrode body 100. Each tab falls toward the inner side in the radial direction. The outer surface of each tab forms a substantially flat surface. Each tab is connected to the second collector plate 420. Each tab can be welded to the second collector plate 420.

[0083] The separator 130 is electrically insulating. The separator 130 electrically separates the first electrode 110 from the second electrode 120. In the radial direction, the separator 130 is arranged between the first electrode 110 and the second electrode 120. The separator 130 is porous. The electrolyte can penetrate into the separator 130. The separator 130 may include, for example, a porous film made of resin. The electrolyte may include, for example, a lithium salt and an organic solvent.

[0084] 2-2. Fixing components

[0085] Figure 2 It is a second schematic cross-sectional view showing an example of the power storage unit in the present embodiment. Figure 2 A cross section orthogonal to the winding axis is shown. The "winding direction" is Figure 2 W direction in the winding direction. In the winding direction, the first electrode 110 has a first terminal portion 110e. The first terminal portion 110e is the winding end portion of the first electrode 110. The second electrode 120 has a second terminal portion 120e. The second terminal portion 120e is the winding end portion of the second electrode 120. The separator 130 has a third terminal portion 130e. The third terminal portion 130e is the winding end portion of the separator 130. In the winding direction, the second terminal portion 120e is located within the range from the first terminal portion 110e to the third terminal portion 130e. At the first terminal portion 110e, the first foil 112 is exposed from the first active material layer 114. The first foil 112 alone forms the first terminal portion 110e. That is, the first terminal portion 110e is composed of the first foil 112. At the second terminal portion 120e, the second foil 122 is exposed from the second active material layer 124. The second terminal portion 120e is formed solely by the second foil 122. That is, the second terminal portion 120e is formed by the second foil 122.

[0086] Fig.12 It is a schematic cross-sectional view showing an example of the cutting position of the electrode original sheet. For example, the first terminal portion 110e can be substantially composed of the first foil 112. In the mode in which the first terminal portion 110e is substantially composed of the first foil 112, a first small piece 114a can be arranged at the top of the first terminal portion 110e. The first small piece 114a is a part of the first active material layer 114. For example, sometimes the first active material layer 114 is intermittently formed on the surface of the first foil 112 in the length direction of the electrode original sheet. The “length direction” is Fig.12 The L direction in the winding electrode body 100. In the winding electrode body 100, the length direction becomes the winding direction. The first electrodes 110 are divided into individual ones by cutting the electrode original sheet. For example, from the viewpoint of material efficiency, etc., the cutting position Cp can be set in the first active material layer 114. After cutting, the first small piece 114a can be arranged at the top of the first terminal portion 110e. The first small piece 114a can be arranged only on one side of the first foil 112. The first small piece 114a can also be arranged on both sides of the first foil 112. The length of the first small piece 114a can be, for example, less than 5 mm, less than 4 mm, less than 3 mm, less than 2 mm, or less than 1 mm. The length of the first small piece 114a can be greater than 0.001 mm, greater than 0.01 mm, greater than 0.05 mm, greater than 0.1 mm, greater than 0.5 mm, or greater than 1 mm. Regarding the second terminal portion 120e, it is the same as the first terminal portion 110e. The second terminal portion 120 e may be substantially constituted by the second foil 122 . A second small piece (not shown) may be disposed at the tip of the second terminal portion 120 e . The second small piece is a part of the second active material layer 124 .

[0087] The fixing member 140 may include, for example, an adhesive tape. The fixing member 140 may be attached to, for example, the third terminal portion 130e. The fixing member 140 prevents the wound electrode body 100 from loosening and maintains its structure. That is, the fixing member 140 fixes the wound electrode body 100 at the third terminal portion 130e.

[0088] (1) Maximum thickness

[0089] Figure 31 is a schematic cross-sectional view showing the first example of the winding end portion in the present embodiment. In the first example, the second terminal portion 120e is away from the first terminal portion 110e. In the first example, the step difference can be reduced according to 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 greater than 0.9×T2. By making the maximum thickness (Tf) greater than 0.9×T2, it is possible to expect a reduction in the step difference. For example, the maximum thickness (Tf) of the fixing member can be less than 1.1×T2. For example, the maximum thickness (Tf) of the fixing member can be equal to the thickness (T2) of the second foil 122.

[0090] Figure 4 : is a schematic cross-sectional view showing the second example of the winding end portion in the present embodiment. In the second example, the second terminal portion 120e is closer to the first terminal portion 110e than in the first example. In the second example, the step difference can be reduced based on 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 less than 1.1×(T1+T2). By making the maximum thickness (Tf) less than 1.1×(T1+T2), it is possible to expect a reduction in the step difference. For example, the maximum thickness (Tf) can be greater than 0.9×(T1+T2). For example, the maximum thickness (Tf) can be equal to the total thickness (T1+T2).

[0091] Furthermore, in the embodiment in which the first small piece 114a is arranged at the tip of the first terminal 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 the embodiment in which the second small piece is arranged at the top of the second terminal 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.

[0092] It is considered that as the second terminal portion 120e approaches the first terminal portion 110e, the structure of the winding end portion can be changed from the first example ( Figure 3 ) to the second example ( Figure 4 ) changes. In the process of change, by making the maximum thickness (Tf) greater than or equal to 0.9×T2 and less than or equal to 1.1×(T1+T2), it is expected that the step difference will be reduced. Therefore, the fixing member 140 satisfies the relationship of the following formula.

[0093] 0.9×T2≤Tf≤1.1×(T1+T2)

[0094] The fixing member 140 may satisfy the following relationship, for example.

[0095] T2≤Tf≤(T1+T2)

[0096] The fixing member 140 may satisfy the following relationship, for example.

[0097] 0.9×T2≤Tf≤1.1×T2

[0098] The fixing member 140 may satisfy the following relationship, for example.

[0099] 0.9×(T1+T2)≤Tf≤1.1×(T1+T2)

[0100] The fixing member 140 may satisfy the following relationship, for example.

[0101] 0.4×(T1+T2)≤Tf≤0.6×(T1+T2)

[0102] The fixing member 140 may satisfy the following relationship, for example.

[0103] 0.6×(T1+T2)≤Tf≤0.9×(T1+T2)

[0104] The fixing member 140 may satisfy the following relationship, for example.

[0105] 0.1×(T1+T2)≤Tf≤0.4×(T1+T2)

[0106] The thickness (T1) of the first foil 112 and the thickness (T2) of the second foil 122 may be, for example, 5 to 100 μm, 5 to 50 μm, 5 to 30 μm, 5 to 20 μm, or 5 to 15 μm, respectively. The thickness (T1, T2, Tf) of each member can be measured using, for example, a constant pressure thickness meter.

[0107] (2) Angle of formation

[0108] The distance between the second terminal portion 120e and the first terminal portion 110e can be determined by, for example, Figure 2 The first angle θ1 is used to evaluate. The first angle θ1 is the angle formed by the first semi-straight line L1 and the second semi-straight line L2. The first angle θ1 is a positive angle. The first semi-straight line L1 is the starting line, and the second semi-straight line L2 is the vector diameter. A "positive angle" is an angle generated by rotating the vector diameter from the starting line in the winding direction along the direction from the starting end toward the terminal end. The endpoints of the first semi-straight line L1 and the second semi-straight line L2 are the winding center 100c. The "winding center" represents the geometric center of the figure formed by the contour line of the wound electrode body 100. The first semi-straight line L1 passes through the first terminal portion 110e. The second semi-straight line L2 passes through the second terminal portion 120e.

[0109] The first angle θ1 may be, for example, greater than 30°. When the first angle θ1 exceeds 30°, the maximum thickness (Tf) of the fixing member 140 is close to the thickness (T2) of the second foil 122, and a reduction in the step difference can be expected. The first angle θ1 may be, for example, greater than 45°, greater than 60°, greater than 90°, greater than 120°, greater than 150°, greater than 180°, greater than 210°, greater than 240°, greater than 270°, greater than 300°, or greater than 330°. The first angle θ1 may be, for example, less than 360°, less than 330°, less than 300°, less than 270°, less than 240°, less than 210°, less than 180°, less than 150°, less than 120°, less than 90°, less than 60°, or less than 45°.

[0110] 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 is close to the total thickness (T1+T2) of the first foil 112 and the second foil 122, and the step difference can be expected to be reduced. 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.

[0111] Furthermore, when the first angle θ1 is 0°, the position of the second terminal portion 120e coincides with the position of the first terminal portion 110e in the winding direction.

[0112] The distance between the third terminal portion 130e and the second terminal portion 120e can be determined by, for example, Figure 2 The second angle θ2 is evaluated. The second angle θ2 is the angle formed by the second semi-straight line L2 and the third semi-straight line L3. The second angle θ2 is a positive angle. The second semi-straight line L2 is the starting line, and the third semi-straight line L3 is the vector diameter. The endpoint of the third semi-straight line L3 is also the winding center 100c. The third semi-straight line L3 passes through the third terminal portion 130e.

[0113] The second angle θ2 may be, for example, 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, 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.

[0114] Furthermore, when the second angle θ2 is 0°, the position of the second terminal portion 120e coincides with the position of the third terminal portion 130e in the winding direction.

[0115] (3) Configuration

[0116] As long as the third terminal portion 130e can be fixed, the configuration of the fixing member 140 is arbitrary. Figure 3 As shown in FIG. 1 and FIG. 2 , a portion of the fixing member 140 may overlap with the third terminal portion 130e. That is, at least a portion of the fixing member 140 may be arranged outside the partition 130 (outermost layer) in the radial direction. Figure 3 Etc. in the R direction.

[0117] Figure 5 1 is a schematic cross-sectional view showing a third example of the winding end portion in the present embodiment. For example, at least a portion of the fixing member 140 may be arranged on the inner side of the separator 130 (outermost layer) in the radial direction.

[0118] Figure 6 1 is a schematic cross-sectional view showing a fourth example of the winding end portion in the present embodiment. For example, at least a portion of the fixing member 140 may overlap with the electrode foil. For example, at least a portion of the fixing member 140 may overlap with the second foil 122. At least a portion of the fixing member 140 may overlap with both the first foil 112 and the second foil 122.

[0119] Figure 7 1 is a schematic cross-sectional view showing a fifth example of the winding end portion in the present embodiment. For example, the fixing member 140 may be adjacent to the electrode foil on the inner side of the outermost layer. For example, the fixing member 140 may be in contact with the second foil 122. There may also be a gap between the fixing member 140 and the electrode foil. In the winding direction, the fixing member 140 may not exceed the third terminal portion 130e.

[0120] (4) Tilt

[0121] Figure 81 is a schematic cross-sectional view showing the sixth example of the winding end portion in the present 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 terminal 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 can be, for example, approximately constant. "Approximately constant" means that the ratio of the maximum value to the minimum value is 1 to 1.2. The ratio of the maximum value to the minimum value can be, for example, 1 to 1.1, or 1 to 1.05. For example, the fixing member 140 can have a maximum thickness at the first end 140s. By having the fixing member 140 show a maximum thickness at the first end 140s, a reduction in the step difference can be expected.

[0122] The fixing member 140 may have an inclination. 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 as it moves from the first end 140s to the second end 140e. By having the fixing member 140 have an inclination, it is possible to expect an improvement in roundness. The inclination may extend over the entire area of ​​the 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" means the thickness of the thinnest portion of the fixing member 140.

[0123] The thickness of the fixing member 140 may, for example, change continuously. For example, the thickness of the fixing member 140 may decrease continuously from the first end 140s toward the second end 140e. The thickness may, for example, decrease linearly. The thickness may, for example, decrease monotonically. The thickness may, for example, decrease nonlinearly. The thickness may, for example, decrease in steps. The thickness may, for example, decay in an exponential function.

[0124] (5) Base layer, adhesive layer

[0125] Fig. 9 It is a schematic cross-sectional view showing an example of a fixing member in the present embodiment. As long as the wound electrode body 100 can be fixed, the fixing member 140 can have any structure. The fixing member 140 can include, for example, a substrate layer 141 and an adhesive layer 142. For example, the substrate layer 141 can have a substantially constant thickness throughout the entirety. At least a portion of the substrate layer 141 can also have an inclination. The adhesive layer 142 can have a substantially constant thickness throughout the entirety. At least a portion of the adhesive layer 142 can also have an inclination.

[0126] The fixing member 140 may be, for example, electrically insulating. The base layer 141 may include, for example, at least one selected from polypropylene (PP), polyimide (PI), polyethylene (PE), polyethylene terephthalate (PET), and polyphenylene sulfide (PPS). The adhesive layer 142 may include, for example, at least one selected from acrylic adhesive materials, silicone adhesive materials, polyurethane adhesive materials, and rubber adhesive materials.

[0127] The fixing member 140 may be constituted by, for example, an adhesive layer 142. The adhesive layer 142 may include, for example, at least one selected from the group consisting of vinyl acetate resin emulsion adhesive, acrylic resin emulsion adhesive, vinyl acetate resin solvent adhesive, acrylic resin solvent adhesive, vinyl chloride resin solvent adhesive, chloroprene rubber solvent adhesive, chloroprene rubber solvent mastic adhesive, nitrile rubber solvent adhesive, polyurethane resin adhesive, epoxy resin adhesive, modified silicone resin adhesive, epoxy-modified silicone resin adhesive, starch adhesive, polymer cement mortar, epoxy resin mortar, and silylated polyurethane resin adhesive.

[0128] 2-3. Unit housing

[0129] The unit housing 200 accommodates the wound electrode body 100. The unit housing 200 may be made of metal, for example. The unit housing 200 may include, for example, Fe, stainless steel, etc. The unit housing 200 is cylindrical. The unit housing 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.

[0130] The top wall 220 is connected to the axial end of the peripheral wall 210. For example, a through hole for connecting to the external terminal 300 may be formed in the central portion 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 the axial end of the peripheral wall 210. The bottom wall 230 contacts the second collector plate 420.

[0131] The external terminal 300 is arranged on the outer surface of the top wall 220. The external terminal 300 has a different polarity from the unit housing 200. The external terminal 300 may have a positive polarity, for example. The unit housing 200 may have a negative polarity, for example. The external terminal 300 may have a negative polarity, for example. The unit housing 200 may have a positive polarity, for example.

[0132] The insulating member 500 electrically separates the external terminal 300 from the unit case 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 unit case 200, the second insulating portion 520 is interposed between the first collector plate 410 and the unit case 200.

[0133] 3. Method for manufacturing power storage unit

[0134] Fig.10 This is a schematic flow chart of the method for manufacturing a storage unit in this embodiment. Hereinafter, the "method for manufacturing a storage unit in this embodiment" may be abbreviated as "this manufacturing method". This manufacturing method includes "(a) winding" and "(b) inserting into a housing".

[0135] 3-1.(a) Winding

[0136] The present manufacturing method includes a step of forming a wound electrode body 100. The details of the wound electrode body 100 are as described above. Prepare the first electrode 110, the second electrode 120, the separator 130 and the fixing member 140. A single separator 130 may be used, or two or more separators 130 may be used. For example, a stack 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 winding the stack into a spiral shape. The wound electrode body 100 can be fixed by attaching the fixing member 140 to the third terminal portion 130e of the separator 130. Furthermore, the formation of the stack and the winding of the stack may be carried out sequentially or simultaneously.

[0137] The manufacturing method may include, for example, a step of providing an inclination to the fixing member 140. For example, during the process of attaching the fixing member 140, the tension applied to the fixing member 140 may be changed.

[0138] Fig.11 1 is a graph showing an example of tension change in this embodiment. At the first time point p1, the attachment starts. At the first time point p1, the first end 140s of the fixing member 140 is attached to the partition 130. The fixing member 140 is gradually attached from the first end 140s side. At the second time point p2, the second end 140e of the fixing member 140 is attached to the partition 130. At the second time point p2, the attachment is completed.

[0139] For example, the tension may be increased in at least one period between the first time point p1 and the second time point p2. By increasing the tension, the fixing member 140 can be given an inclination. For example, at the first time point p1, the first tension F1 is applied. At the second time point p2, the second tension F2 is applied. 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, greater than 1.1, greater than 1.2, greater than 1.5, or greater than 2. The ratio (F2 / F1) may be, for example, less than 2, less than 1.5, less than 1.2, or less than 1.1. The increase in tension may be, for example, continuous. For example, during the period from the first time point p1 to the second time point p2, the tension may increase monotonically. The increase in tension may also be, for example, staged. For example, during the period from the first time point p1 to the second time point p2, the tension may increase in a step-like manner. For example, during the period from the first time point p1 to the second time point p2, the tension may increase exponentially.

[0140] 3-2.(b) Insert into the housing

[0141] The present manufacturing method includes a process of manufacturing a storage cell 1 by housing a wound electrode body 100 in a cell casing 200. The wound electrode body 100 is inserted into the cell casing 200 in a manner such that the winding axis of the wound electrode body 100 is parallel to the axial direction of the cell casing 200. The first electrode 110 is electrically connected to the external terminal 300. The second electrode 120 is electrically connected to the cell casing 200. After the wound electrode body 100 is inserted, an electrolyte can be injected into the cell casing 200. The storage cell 1 is completed by sealing the cell casing 200. For example, the bottom wall 230 can be welded to the peripheral wall 210 by laser or the like.

Claims

1. A power storage unit, It includes a unit housing and a wound electrode body, The unit housing is cylindrical. The unit 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 the winding direction of the wound electrode body, the first electrode has a first terminal portion, the second electrode has a second terminal portion, and the separator has a third terminal portion. In the winding direction, the second terminal portion is located within the range from the first terminal portion to the third terminal portion, The first terminal portion is formed of the first foil, The second terminal portion is formed of the second foil, The fixing member fixes the wound electrode body at the third terminal portion. The fixing member satisfies the relationship of 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.

2. The power storage unit according to claim 1, The fixing member also satisfies the relationship of 0.9×T2≤Tf≤1.1×T2.

3. The power storage unit according to claim 2, In a cross section orthogonal to the winding axis of the wound electrode body, The angle between the first and second semi-lines exceeds 30°, The endpoints of the first half straight line and the second half straight line are winding centers, The first half straight line passes through the first terminal portion, and The second half straight line passes through the second terminal portion.

4. The power storage unit according to claim 1, The fixing member also satisfies the relationship of 0.9×(T1+T2)≤Tf≤1.1×(T1+T2).

5. The power storage unit according to claim 4, In a cross section orthogonal to the winding axis of the wound electrode body, The angle between the first and second half lines is less than 30°. The endpoints of the first half straight line and the second half straight line are winding centers, The first half straight line passes through the first terminal portion, and The second half straight line passes through the second terminal portion.

6. The power storage unit according to any one of claims 1 to 5, The fixing member has a first end and a second end, In the winding direction, the first end is the starting end of the fixing member. In the winding direction, the second end is located on the opposite side of the first end, and The fixing member has the maximum thickness at the first end portion.

7. The power storage unit according to claim 6, In at least a portion between the first end and the second end, a thickness of the fixing member decreases as it goes from the first end toward the second end.

8. The power storage unit according to claim 1, The first electrode is a positive electrode, and The second electrode is a negative electrode.

9. A method for manufacturing a power storage unit, comprising: (a) forming a wound electrode body; and (b) manufacturing a power storage cell by housing the wound electrode body in a cell case, The unit housing 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 terminal portion, the second electrode has a second terminal portion, and the separator has a third terminal portion. In the winding direction, the second terminal portion is located within the range from the first terminal portion to the third terminal portion, The first terminal portion is formed of the first foil, The second terminal portion is formed of the second foil, The fixing member fixes the wound electrode body at the third terminal portion. The fixing member satisfies the relationship of 0.9×T2≤Tf≤1.1×(T1+T2), In the 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.

10. The method for manufacturing a power storage unit according to claim 9, The fixing member also satisfies the relationship of 0.9×T2≤Tf≤1.1×T2.

11. The method for manufacturing a power storage unit according to claim 9, The fixing member also satisfies the relationship of 0.9×(T1+T2)≤Tf≤1.1×(T1+T2).

12. The method for manufacturing a power storage unit according to any one of claims 9 to 11, The wound electrode body is fixed by attaching the fixing member to the third terminal portion. The fixing member has a first end and a second end, In the winding direction, the first end is the 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, and During at least one period from the start of attachment to the end of attachment of the fixing member, tension applied to the fixing member increases.

13. The method for manufacturing a power storage unit according to claim 9, The first electrode is a positive electrode, and The second electrode is a negative electrode.

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