Method for manufacturing an energy storage element and apparatus for manufacturing an energy storage element

Abstract

The present invention provides a method for manufacturing energy storage elements that enables the production of energy storage elements with improved reliability. [Solution] A method for manufacturing an energy storage element comprising an electrode body 400 around which an electrode plate is wound, and a container for housing the electrode body, wherein the electrode plate has a forming portion on which an active material layer is formed, the electrode body has a pair of turned portions 402 and a flat portion 403 connecting the pair of turned portions, the forming portion has a convex portion 480 projecting in the thickness direction of the electrode plate, the convex portion is arranged at least on the turned portion, and the manufacturing method includes housing the electrode body in the container in a position where the flat portion is sandwiched between a pair of walls facing each other in the container, and charging the energy storage element while the pair of walls are compressed in the opposing direction of the pair of walls.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a power storage element and a manufacturing apparatus for a power storage element.

Background Art

[0002] Patent Document 1 discloses a secondary battery including a wound electrode body in which a positive electrode and a negative electrode are wound around a winding shaft with a separator interposed therebetween.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above conventional secondary battery, when the power storage element is charged in a state where the wound electrode body is compressed, the active material layers provided on the positive electrode and the negative electrode may peel off. If the active material layer peels off, it may have an adverse effect on battery performance and may impair reliability.

[0005] The present invention has been made by the inventors of the present application newly focusing on the above problems, and an object thereof is to provide a method for manufacturing a power storage element and the like capable of manufacturing a power storage element with improved reliability.

Means for Solving the Problems

[0006] A method for manufacturing an energy storage element according to one aspect of the present invention is a method for manufacturing an energy storage element comprising an electrode body in which an electrode plate is wound, and a container for housing the electrode body, wherein the electrode plate has a forming portion on which an active material layer is formed, the electrode body has a pair of turned portions and a flat portion connecting the pair of turned portions, the forming portion has a convex portion projecting in the thickness direction of the electrode plate, the convex portion is arranged at least on the turned portion, and the manufacturing method includes housing the electrode body in the container in a position in which the flat portion is sandwiched between a pair of walls facing each other in the container, and charging the energy storage element while the pair of walls are compressed in the opposing direction of the pair of walls.

[0007] An apparatus for manufacturing an energy storage element according to one aspect of the present invention comprises an electrode body in which an electrode plate is wound, and a container for housing the electrode body, wherein the electrode plate has a forming portion in which an active material layer is formed, the electrode body has a pair of turned portions and a flat portion connecting the pair of turned portions, the forming portion has a convex portion projecting in the thickness direction of the electrode plate, the convex portion is arranged at least on the turned portion, and the manufacturing apparatus comprises a housing portion for housing the electrode body in the container in a position in which the flat portion is sandwiched between a pair of walls facing each other in the container, a compression portion for compressing the pair of walls in the opposing direction of the pair of walls, and a charging portion for charging the energy storage element while the pair of walls are compressed by the compression portion. [Effects of the Invention]

[0008] According to the present invention, it is possible to manufacture energy storage elements with improved reliability. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a perspective view showing the external appearance of an energy storage element according to an embodiment. [Figure 2] Figure 2 is a perspective view showing the components arranged inside the container of the energy storage element according to the embodiment. [Figure 3] Figure 3 is a perspective view showing an overview of the configuration of the electrode body according to the embodiment. [Figure 4] Figure 4 is a cross-sectional view showing the electrode body according to the embodiment housed in a container. [Figure 5A] Figure 5A is a cross-sectional view showing a protrusion according to the embodiment. [Figure 5B] Figure 5B is a cross-sectional view showing a modified example of the protrusion according to the embodiment. [Figure 6] Figure 6 is a partial cross-sectional view showing a portion of the electrode plate forming the vicinity of the turn portion according to the embodiment. [Figure 7] Figure 7 is a block diagram showing a manufacturing apparatus for an energy storage element according to an embodiment. [Figure 8] Figure 8 is an explanatory diagram showing the state in which the container is compressed by the compression part according to the embodiment. [Figure 9] Figure 9 is a partial cross-sectional view showing a portion of the electrode body near the turn portion according to Modified Example 1. [Figure 10] Figure 10 is a partial cross-sectional view showing a portion of the electrode body near the turn portion according to Modified Example 2. [Figure 11] Figure 11 is a partial cross-sectional view showing a portion of the electrode body near the turn portion according to Modification 3. [Modes for carrying out the invention]

[0010] (1) A method for manufacturing an energy storage element according to one aspect of the present invention is a method for manufacturing an energy storage element comprising an electrode body in which an electrode plate is wound, and a container for housing the electrode body, wherein the electrode plate has a forming portion on which an active material layer is formed, the electrode body has a pair of turned portions and a flat portion connecting the pair of turned portions, the forming portion has a convex portion projecting in the thickness direction of the electrode plate, the convex portion is arranged at least on the turned portion, and the manufacturing method includes housing the electrode body in the container in a position in which the flat portion is sandwiched between a pair of walls facing each other in the container, and charging the energy storage element while the pair of walls are compressed in the opposing direction of the pair of walls.

[0011] According to the method for manufacturing an energy storage element described in (1) above, since the convex portion is disposed at the turning portion of the electrode body, a gap is provided between the electrode plates at the turning portion by this convex portion. When the electrode body expands while being constrained by the pair of wall portions, the stress is absorbed as the convex portion and the gap become smaller, so that it becomes difficult for stress to act on the active material layer, and peeling of the active material layer can be suppressed. Thus, if peeling of the active material layer can be suppressed, it leads to suppression of capacitance reduction, so that the reliability of the energy storage element can be improved.

[0012] (2) In the method for manufacturing an energy storage element described in (1) above, the occupied area per unit area of the convex portion in the turning portion may be larger than the occupied area per unit area of the convex portion in the flat portion.

[0013] According to the method for manufacturing an energy storage element described in (2) above, since the occupied area of the convex portion in the turning portion is larger than the occupied area of the convex portion in the flat portion, the gap between the electrode plates can be suppressed in the flat portion. Thereby, in the flat portion, the electrode plates can be laminated densely, and it is possible to increase the capacitance.

[0014] (3) In the method for manufacturing an energy storage element described in (2) above, the occupied area of the convex portion in the flat portion may be zero.

[0015] According to the method for manufacturing an energy storage element described in (3) above, since the occupied area of the convex portion in the flat portion is zero, the gap between the electrode plates can be further suppressed in the flat portion. Thereby, in the flat portion, the electrode plates can be laminated more densely, and it is possible to increase the capacitance more.

[0016] (4) In the method for manufacturing an energy storage element described in (1) above, the occupied area per unit area of the convex portion in the turning portion and the occupied area per unit area of the convex portion in the flat portion may be equal.

[0017] According to the method for manufacturing the energy storage element described in (4) above, the area occupied by the convex portion in the turned portion is the same as the area occupied by the convex portion in the flat portion, so that the convex portion can be formed uniformly on the electrode plate. Therefore, an electrode body having a convex portion can be easily manufactured.

[0018] (5) In the method for manufacturing an energy storage element described in any one of (1) to (4) above, the electrode plate may comprise a positive electrode plate and a negative electrode plate, wherein the protrusions are formed on the formed portion of the positive electrode plate and the formed portion of the negative electrode plate, respectively.

[0019] According to the manufacturing method of the energy storage element described in (5) above, since protrusions are formed in both the positive electrode plate formation portion and the negative electrode plate formation portion, the number of protrusions and voids arranged in the turn portion can be increased. This allows for more reliable absorption of stress when the electrode body expands.

[0020] (6) Another embodiment of the present invention relates to a manufacturing apparatus for an energy storage element, comprising an electrode body around which an electrode plate is wound, and a container for housing the electrode body, wherein the electrode plate has a forming portion on which an active material layer is formed, the electrode body has a pair of turned portions and a flat portion connecting the pair of turned portions, the forming portion has a convex portion projecting in the thickness direction of the electrode plate, the convex portion is arranged at least on the turned portion, and the manufacturing apparatus comprises a housing portion for housing the electrode body in the container in a position where the flat portion is sandwiched between a pair of walls facing each other in the container, a compression portion for compressing the pair of walls in the opposing direction of the pair of walls, and a charging portion for charging the energy storage element while the pair of walls are compressed by the compression portion.

[0021] According to the manufacturing apparatus for the energy storage element described in (6) above, a protrusion is arranged in the turn portion of the electrode body, and this protrusion creates a gap between the electrode plates in the turn portion. When the electrode body expands while constrained by a pair of walls, the protrusion becomes smaller, absorbing the stress, which reduces the stress acting on the active material layer and suppresses delamination of the active material layer. By suppressing delamination of the active material layer in this way, the reliability of the energy storage element can be improved.

[0022] (Embodiment) The method for manufacturing an energy storage element according to an embodiment of the present invention will be described below with reference to the drawings. Note that the embodiments described below are all general or specific examples. The numerical values, shapes, materials, components, arrangement and connection configurations of components, manufacturing processes, and the order of manufacturing processes shown in the following embodiments are examples and are not intended to limit the present invention. Furthermore, dimensions and other specifications in each figure are not strictly illustrated. Additionally, the same or similar components are denoted by the same reference numerals in each figure. The drawings are schematic diagrams with appropriate emphasis, omissions, and adjustments of proportions to illustrate the present invention, and may differ from the actual shapes, positional relationships, and proportions.

[0023] In the following description and drawings, the direction in which the pair of terminals are aligned, the longitudinal direction of the container, and the winding axis direction of the electrode plate are defined as the X-axis direction; the thickness direction of the container and the thickness direction of the electrode body are defined as the Y-axis direction; and the direction in which the container body and lid are aligned and the electrode body and lid are aligned are defined as the Z-axis direction. These X-axis, Y-axis, and Z-axis directions intersect each other (orthogonal in this embodiment). Depending on the orientation of the energy storage element, the Z-axis direction may not be vertical, but for the sake of explanation, the Z-axis direction will be described as vertical.

[0024] In the following explanation, for example, the "X-axis positive direction" refers to the direction of the X-axis arrow, and the "X-axis negative direction" refers to the opposite direction. The same applies to the Y-axis and Z-axis directions. When simply referred to as "X-axis direction," it means either the bidirectional or unidirectional direction parallel to the X-axis. The same applies to the terminology related to the Y-axis and Z-axis.

[0025] Furthermore, expressions indicating relative directions or orientations, such as parallel and orthogonal, include cases where the direction or orientation is not strictly accurate. For example, two directions being orthogonal does not only mean that the two directions are perfectly orthogonal, but also that they are substantially orthogonal, i.e., include a difference of a few percent. In the following explanation, when the term "insulation" is used, it means "electrical insulation." The volume resistivity of an insulating material is 1 × 10⁻⁶ 6 Preferably, it is Ωm or higher, 1 × 10 7 Ωm or greater is more preferable, 1 × 10 10 A value of Ωm or greater is even more preferable.

[0026] [Energy storage element] A general description of the energy storage element 10 according to the embodiment will be given. Figure 1 is a perspective view showing the external appearance of the energy storage element 10 according to the embodiment. Figure 2 is a perspective view showing the components arranged inside the container 100 of the energy storage element 10 according to the embodiment.

[0027] The energy storage element 10 is a secondary battery, more specifically a non-aqueous electrolyte secondary battery such as a lithium-ion secondary battery. The energy storage element 10 is used as a battery for driving or starting the engine of mobile vehicles such as automobiles, motorcycles, watercraft, ships, snowmobiles, agricultural machinery, construction machinery, automated guided vehicles (AGVs), or railway vehicles for electric railways. Examples of automobiles include electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and fossil fuel (gasoline, diesel, liquefied natural gas, etc.) vehicles. Examples of railway vehicles for electric railways include electric trains, monorails, maglev trains, and hybrid trains equipped with both diesel engines and electric motors. The energy storage element 10 can also be used as a stationary battery for household or commercial use.

[0028] The energy storage element 10 is not limited to a non-aqueous electrolyte secondary battery, but may be a secondary battery other than a non-aqueous electrolyte secondary battery, or a capacitor. The energy storage element 10 may also be a primary battery.

[0029] As shown in Figure 1, the energy storage element 10 comprises a container 100 and a pair of terminals 200 (positive and negative). As shown in Figure 2, a pair of current collectors 300 and electrode bodies 400 (positive and negative) are housed inside the container 100.

[0030] In addition to the components described above, the energy storage element 10 may also include a spacer positioned to the side of the current collector 300, a gas release valve for releasing pressure when the pressure inside the container 100 rises, and an insulating film that encloses the electrode body 400, etc. An electrolyte (non-aqueous electrolyte) is sealed inside the container 100, but this is not shown in the illustration. There are no particular restrictions on the type of electrolyte as long as it does not impair the performance of the energy storage element 10, and various types can be selected.

[0031] The container 100 comprises a rectangular cylindrical container body 110 with a bottom, and a lid 120 that closes the opening of the container body 110. The container body 110 comprises a bottom wall 111, a pair of first wall portions 112, and a pair of second wall portions 113. The bottom wall 111 is a rectangular flat plate portion with the X-axis direction as its longitudinal direction. The pair of first wall portions 112 are rectangular flat plate portions extending in the Z-axis direction from each long side of the bottom wall 111. The pair of second wall portions 113 are rectangular flat plate portions extending in the Z-axis direction from each short side of the bottom wall 111. Each first wall portion 112 and each second wall portion 113 are integrated into a rectangular cylindrical shape. The lid 120 is a rectangular flat plate with the X-axis direction as its longitudinal direction. Although not shown in the illustration, a liquid pouring port is formed in the lid 120. The liquid injection port is a part used to inject electrolyte into the container 100 during the manufacturing of the energy storage element 10, and is closed after injection.

[0032] After the electrode body 400 and the like are placed inside the container 100, the inside of the container 100 is sealed by joining the lid 120 and the container body 110 by welding or other means. The material of the container body 110 and the lid 120 is not particularly limited, but it is preferable that they be made of a weldable metal such as stainless steel, aluminum, aluminum alloy, iron, or plated steel sheet.

[0033] Terminal 200 is an electrode terminal electrically connected to the electrode body 400 via the current collector 300. That is, the positive terminal 200 is electrically connected to the positive electrode plate of the electrode body 400 via the current collector 300, and the negative terminal 200 is electrically connected to the negative electrode plate of the electrode body 400 via the current collector 300. Terminal 200 is attached to a cover 120 positioned above the electrode body 400 via an insulating gasket (not shown).

[0034] [Electrode body] Figure 3 is a perspective view showing an overview of the configuration of the electrode body 400 according to the embodiment. In Figure 3, elements such as the laminated and wound electrode plate 401 are partially unfolded and shown. In Figure 3, only some of the multiple protrusions 480 on the electrode plate 401 are schematically represented. The winding axis W shown in Figure 3 is a hypothetical axis that serves as the central axis when winding the electrode plate 401, etc.

[0035] As shown in Figure 3, the electrode body 400 comprises two electrode plates 401 and two separators 430, and is an energy storage element (power generation element) capable of storing electricity. In this embodiment, the electrode body 400 is a wound-type electrode body formed by winding two electrode plates 401 and two separators 430 without a winding core, but it may also be a wound-type electrode body wound around a winding core. As shown in Figure 3, the electrode body 400 has a flattened shape in the direction perpendicular to the winding axis W. That is, when viewed from the direction of the winding axis W, the electrode body 400 has an overall oval shape, with the oval straight portion being flat and the oval curved portion being curved. For this reason, the electrode body 400 comprises a pair of opposing turn portions 402 (curved portions that face each other in the longitudinal direction of the oval shape, with the winding axis W in between) and a flat portion 403 which is the portion between the pair of turn portions 402. The flat section 403 is the part that connects the pair of turned sections 402.

[0036] In this embodiment, the electrode body 400 comprises two electrode plates 401, a positive electrode plate 410 which is the positive electrode plate 401, and a negative electrode plate 420 which is the negative electrode plate 401. The positive electrode plate 410 is an electrode plate in which a positive electrode active material layer 414 is formed on at least one of the front and back surfaces of a long, strip-shaped metal foil current collector foil 411. The negative electrode plate 420 is an electrode plate in which a negative electrode active material layer 424 is formed on at least one of the front and back surfaces of a long, strip-shaped metal foil current collector foil 421. More specifically, the positive electrode plate 410 comprises a formed portion 415 in which the active material layer 414 is formed, and a non-formed portion 416 in which the active material layer 414 is not formed. The non-formed portion 416 is the portion in which the positive electrode current collector foil 411 is exposed. The negative electrode plate 420 comprises a formed portion 425 on which an active material layer 424 is formed, and a non-formed portion 426 on which the active material layer 424 is not formed. The non-formed portion 426 is the portion where the current collector foil 421 of the negative electrode is exposed.

[0037] The positive electrode current collector foil 411 is made of aluminum or an aluminum alloy, etc. The negative electrode current collector foil 421 is made of copper or a copper alloy, etc. The active material layer 414 includes a positive electrode active material, a binder, and a conductive material, etc. The active material layer 424 includes a negative electrode active material, a binder, and a thickener, etc. As the positive electrode active material and the negative electrode active material, any known material can be used as long as it is a material capable of intercalating and releasing charge transport ions.

[0038] As the positive electrode active material, it is preferable to use Ni-containing layered lithium transition metal oxides such as LiNiMO2 (where M is one or more metal elements selected from Mn, Co, Al, etc.). As the negative electrode active material, it is preferable to use carbon materials such as graphite, or silicon compounds such as silicon, silicon oxides, silicon-carbon composites, or mixtures thereof.

[0039] The separator 430 is a microporous sheet made of resin. Any known material can be used for the separator 430, as long as it does not impair the performance of the energy storage element 10. For example, the separator 430 can be a woven fabric, a nonwoven fabric, or a synthetic resin microporous membrane made of polyolefin resin such as polyethylene, which is insoluble in organic solvents.

[0040] In this embodiment, the electrode body 400 has a positive electrode plate 410 and a negative electrode plate 420 wound around each other via a separator 430, offset from each other in the winding axis direction. The positive electrode plate 410 and the negative electrode plate 420 have portions (unformed portions 416, 426) at their respective offset ends where the active material layer is not formed and the current collector foil is exposed. In other words, the electrode body 400 has a positive electrode connection portion 456 formed by winding and stacking the unformed portion 416 at one end in the winding axis direction. The electrode body 400 has a negative electrode connection portion 466 formed by winding and stacking the unformed portion 426 at the other end in the winding axis direction. The positive electrode connection portion 456 is joined to the positive electrode current collector 300, and the negative electrode connection portion 466 is joined to the negative electrode current collector 300 (see Figure 2). As a result, the positive terminal 200 and the positive electrode connection portion 456 of the electrode body 400 are electrically connected via the positive electrode current collector 300. The negative terminal 200 and the negative electrode connection portion 466 of the electrode body 400 are electrically connected via the negative electrode current collector 300.

[0041] Figure 4 is a cross-sectional view showing the electrode body 400 according to the embodiment housed in the container 100. As shown in Figure 4, when the electrode body 400 is housed in the container 100, the winding axis W is arranged parallel to the X-axis direction. In this state, the flat portion 403 of the electrode body 400 is sandwiched between a pair of first wall portions 112. Since there is no winding core in the central part of the electrode body 400, a linear slit 409 extending in the Z-axis direction is provided between the innermost electrode plates 401 of the electrode body 400. The slit 409 is continuous throughout the entire electrode body 400 along the winding axis direction (X-axis direction).

[0042] [Multiple protrusions on the electrode plate] In the energy storage element 10 configured as described above, the electrode plate 401 provided on the electrode body 400 is provided with a plurality of protrusions 480 that project in the thickness direction. Specifically, as shown in Figure 3, each electrode plate 401 (positive electrode plate 410 and negative electrode plate 420) has a plurality of protrusions 480 on the forming portions 415 and 425. Each protrusion 480 is a point-shaped protrusion. The plan view shape of each protrusion 480 may be circular, elliptical, oblong, or polygonal.

[0043] Figure 5A is a cross-sectional view showing a protrusion 480 according to the embodiment. Here, a positive electrode plate 410 is used as an example for the electrode plate 401, but the same applies to a negative electrode plate 420. Furthermore, although an example is given in which an active material layer 414 is formed on both the front and back surfaces of the current collector foil 411, the active material layer 414 may be formed on only one of the front or back surfaces of the current collector foil 411. As shown in Figure 5A, the protrusions 480 are formed by embossing the electrode plate 401. Because the protrusions 480 are point-like protrusions, each protrusion 480 can be easily formed using embossing. As the protrusions 480 are formed by embossing, the protrusions 480 are formed on the surface of the electrode plate 401, and recesses 481 corresponding to the protrusions 480 are formed on the back surface of the electrode plate 401. Specifically, the recesses 481 are formed in the active material layer 414 on the back side of the electrode plate 401, and the protrusions 480 are formed in the active material layer 414 on the front side. The cross-sectional shape of the protrusions 480 is not limited to this.

[0044] Figure 5B is a cross-sectional view showing a modified example of the protrusion 480 according to the embodiment. In Figure 5B, the active material layer 414 on the back side of the current collector foil 411 in the electrode plate 401 is flat, but the protrusion 480b is formed on the active material layer 414 on the front side. In Figures 5A and 5B, the orientation of the protrusions 480 and 480b may be opposite.

[0045] Figure 6 is a partial cross-sectional view of a portion of the electrode plate 401 that forms the vicinity of the turn portion 402 according to the embodiment. In Figure 6, each protrusion 480 is exaggerated compared to its actual size in order to make it easier to understand. As shown in Figure 6, the turn portion 402 is formed in a semicircular shape in cross-section. In the turn portion 402, a gap is formed between each electrode plate 401 and the separator 430 due to each protrusion 480 and recess 481.

[0046] As shown in Figures 3 and 6, the multiple protrusions 480 are positioned on each electrode plate 401 at locations corresponding to the turn portion 402, and not at locations corresponding to the flat portion 403. Thus, the area occupied by the protrusions 480 in the flat portion 403 is zero, and therefore, the area occupied per unit area of ​​the protrusions 480 in the turn portion 402 is larger than the area occupied per unit area of ​​the protrusions 480 in the flat portion 403. The occupied area is the area of ​​the protrusions 480 within a unit area in the turn portion 402 or the flat portion 403 (if there are multiple protrusions 480, it is the sum of the areas of each protrusion 480). Also, the unit area in the turn portion 402 and the unit area in the flat portion 403 are the same area.

[0047] In each turn section 402, the multiple protrusions 480 are arranged generally evenly throughout the winding axis direction of the forming sections 415 and 425 (see Figure 3). The layout of the multiple protrusions 480 can be anything as long as they are evenly distributed, but examples include a square grid or a triangular grid. Figure 3 shows the case where the multiple protrusions 480 are distributed in a square grid, but if the multiple protrusions 480 are distributed in a triangular grid, the protrusions 480 can be arranged more densely, which is preferable from the viewpoint of increasing the gaps caused by the protrusions.

[0048] [Manufacturing method for energy storage elements] Next, a method for manufacturing an energy storage element will be described. Figure 7 is a block diagram showing an energy storage element manufacturing apparatus 500 according to an embodiment. The manufacturing apparatus 500 shown in Figure 7 is used to manufacture an energy storage element, and an energy storage element 10 is produced. As shown in Figure 7, the manufacturing apparatus 500 includes an assembly section 510, a housing section 520, a container welding section 530, a liquid injection section 540, a compression section 545, a charging section 550, and a control section 560.

[0049] The assembly unit 510 assembles the terminals 200, current collector 300, gasket, and electrode body 400 onto the cover 120 to form an assembly. The assembly unit 510 includes at least one arm device for gripping and assembling the cover 120, terminals 200, current collector 300, gasket, and electrode body 400, a welding device for welding the current collector 300 to the electrode body 400, a crimping device for crimping the terminals 200 to the current collector 300, and the like.

[0050] The housing section 520 assembles the assembly into the container body 110 so that the current collector 300 and the electrode body 400 are housed inside the container body 110. At this time, the housing section 520 houses the electrode body 400 inside the container body 110 in a position where the flat portion 403 is sandwiched between a pair of first wall portions 112 of the container body 110. The housing section 520 is equipped with a fixing portion for fixing the container body 110, an arm portion for gripping and assembling the assembly relative to the fixed container body 110, and the like.

[0051] The container welding section 530 welds the container body 110 and the lid 120 together, sealing the container 100. The container welding section 530 includes a laser welding section for welding the container body 110 and the lid 120, a movable section for moving the laser welding section along the joint surface between the container body 110 and the lid 120, and the like.

[0052] The liquid injection unit 540 pours the electrolyte into the liquid injection port of the container 100 to fill the container 100 with electrolyte, and then seals the liquid injection port of the container 100. The liquid injection unit 540 is equipped with a liquid injection nozzle for pouring the electrolyte into the liquid injection port of the container 100, a sealing unit for plugging and closing the liquid injection port of the container 100, and so on. The energy storage element 10 is then completed.

[0053] The compression part 545 compresses the pair of first wall portions 112 of the container 100 by gripping them in the opposing direction (Y-axis direction). Figure 8 is an explanatory diagram showing the state in which the container 100 is compressed by the compression part 545 according to the embodiment. As shown in Figure 8, the compression part 545 is equipped with a pair of gripping parts 546 that can be opened and closed in the Y-axis direction. The pair of gripping parts 546 compress the pair of first wall portions 112 of the container 100 by gripping them in the Y-axis direction (see arrow Yc). Due to the compression by each gripping part 546, in the flat portion, the electrode plates 401 that form the innermost circumference of the electrode body 400 are arranged directly or indirectly without any gaps. Here, if no other member (such as a separator 430) is provided between the electrode plates 401 that form the innermost circumference of the electrode body 400, the electrode plates 401 will be in close contact with each other due to the compression and there will be no gaps. This case is included in the statement "the electrode plates 401 are directly and without gaps between them."

[0054] On the other hand, when a separator 430 is provided between the innermost electrode plates 401 of the electrode body 400, the electrode plates 401 and the separator 430 are pressed together, eliminating any gaps. Furthermore, in the case of an electrode body 400 equipped with a winding core, this includes a configuration in which the electrode plates 401 and the winding core are pressed together, eliminating any gaps, and a configuration in which the electrode plates 401, the separator 430, and the winding core are pressed together, eliminating any gaps. These cases are included in "the electrode plates 401 are indirectly arranged without gaps."

[0055] The pair of gripping portions 546 are positioned opposite the flat portion 403 of the electrode body 400. Specifically, the Z-axis positive end of each gripping portion 546 is positioned further in the Z-axis positive direction than the Z-axis positive end of the flat portion 403, and the Z-axis negative end of each gripping portion 546 is positioned further in the Z-axis negative direction than the Z-axis negative end of the flat portion 403. This allows the entire area of ​​the formed portions 415 and 425 in the flat portion 403 to be compressed, and the expansion of the flat portion 403 can be more reliably suppressed by each gripping portion 546.

[0056] The pair of gripping portions 546 only need to be able to compress more than half of the area of ​​either the forming portion 415 or the forming portion 425 on the flat portion 403, but as described above, it is preferable that they can compress the entire area of ​​the forming portions 415 and 425 on the flat portion 403.

[0057] The charging unit 550 pre-charges the energy storage element 10 that has been compressed by the compression unit 545. Pre-charging includes not only charging once before shipment, but also charging after repeated charging and discharging. The charging unit 550 includes a power supply unit that supplies power to the energy storage element 10. When discharging is performed, the charging unit 550 includes a charge / discharge unit that charges and discharges the energy storage element 10 instead of the power supply unit.

[0058] The control unit 560 is equipped with a CPU, RAM, ROM, etc., and controls the assembly unit 510, housing unit 520, container welding unit 530, liquid injection unit 540, compression unit 545, and charging unit 550 by having the CPU load a program stored in the ROM into the RAM and execute it. The program causes each unit to execute a method for manufacturing the energy storage element.

[0059] The control unit 560 controls the assembly unit 510 to assemble the terminals 200, current collector 300, gasket, and electrode body 400 onto the cover 120, thereby forming the assembly.

[0060] Subsequently, the control unit 560 controls the housing unit 520 to assemble the assembly into the container body 110 so that the current collector 300 and electrode body 400 are housed inside the container body 110. At this time, the housing unit 520 houses the electrode body 400 inside the container body 110 in a position where the flat portion 403 is sandwiched between a pair of first wall portions 112 of the container body 110. Next, the control unit 560 controls the container welding unit 530 to weld the container body 110 and the lid 120 together, sealing the container 100. Next, the control unit 560 controls the liquid injection unit 540 to pour electrolyte into the liquid injection port of the container 100 to fill the container 100 with electrolyte, and then seals the liquid injection port of the container 100. Next, the control unit 560 controls the compression unit 545 to grip the container 100 of the energy storage element 10 with the gripping unit 546 and compress it. Next, the control unit 560 controls the charging unit 550 to pre-charge the compressed energy storage element 10.

[0061] During pre-charging, the electrode body 400 expands. If the electrode body 400 does not have a protrusion 480 on the electrode plate 401, the stress due to expansion concentrates on the turn portion 402 because there is no gap at the innermost circumference of the electrode body 400 due to compression (see dashed arrow Y10 shown in Figure 8). As a result, the possibility of delamination of the active material layers 414 and 424 in the turn portion 402 increases.

[0062] In contrast, the electrode body 400 of this embodiment is provided with multiple protrusions 480 on the turned portion 402. In other words, since each protrusion 480 is present on the turned portion 402, stress is absorbed when each protrusion 480 is crushed and becomes smaller or the void becomes smaller. As a result, stress is less likely to act on the active material layers 414 and 424, and peeling of the active material layers 414 and 424 can be suppressed.

[0063] [Effects, etc.] As described above, according to this embodiment, since a protrusion 480 is arranged on the turn portion 402 of the electrode body 400, this protrusion 480 creates a gap between the electrode plates 401 in the turn portion 402. When the electrode body 400 expands while constrained by the pair of first wall portions 112, the protrusion 480 and the gap become smaller, absorbing stress. As a result, stress is less likely to act on the active material layers 414 and 424, and peeling of the active material layers 414 and 424 can be suppressed. In this way, suppressing the peeling of the active material layers 414 and 424 leads to suppression of capacitance reduction, and thus improves the reliability of the energy storage element 10.

[0064] Because the area occupied by the protrusions 480 in the turned section 402 is larger than the area occupied by the protrusions 480 in the flat section 403, the gaps between the electrode plates 401 can be suppressed in the flat section 403. As a result, the electrode plates 401 can be densely stacked in the flat section 403, making it possible to increase the energy density.

[0065] In particular, since the area occupied by the protrusions 480 in the flat section 403 is zero, the gap between the electrode plates 401 can be further suppressed in the flat section 403. As a result, the electrode plates 401 can be stacked more densely in the flat section 403, making it possible to further increase the energy density.

[0066] Since protrusions 480 are formed on both the forming portion 415 of the positive electrode plate 410 and the forming portion 425 of the negative electrode plate 420, the number of protrusions 480 and voids arranged in the turn portion 402 can be increased. This allows for more reliable absorption of stress when the electrode body 400 expands.

[0067] (modified version) The following describes various modifications of the above embodiments. In the following description, parts identical to those in the above embodiments or other modifications may be denoted by the same reference numerals and their descriptions may be omitted.

[0068] [Example 1] In the above embodiment, an electrode body 400 was shown in which protrusions 480 are provided on both the positive electrode plate 410 and the negative electrode plate 420. In this modified example 1, an electrode body 400a in which protrusions 480 are provided only on the positive electrode plate 410 will be described. Figure 9 is a partial cross-sectional view taken from a part of the vicinity of the turn portion 402a of the electrode body 400a according to modified example 1. Figure 9 corresponds to Figure 6.

[0069] As shown in Figure 9, the positive electrode plate 410 has multiple protrusions 480 in the area corresponding to the turn portion 402a, but the negative electrode plate 420a does not have multiple protrusions 480 in the area corresponding to the turn portion 402a. In other words, the negative electrode plate 420a does not have protrusions 480 throughout its entirety. Thus, even though the negative electrode plate 420a does not have protrusions 480, the protrusions 480 of the positive electrode plate 410 allow a gap to be created between the positive electrode plate 410 and the negative electrode plate 420a in the turn portion 402a.

[0070] [Differentiation 2] In the above embodiment, an example was given in which no protrusion 480 is formed on the flat portion 403 of the electrode plate 401. In this modified example 2, an electrode body 400b in which a protrusion 480b is formed on the flat portion 403b of the electrode plate 401b will be described. Figure 10 is a partial cross-sectional view taken from a part of the vicinity of the turned portion 402b of the electrode body 400b according to the modified example 2. Figure 10 corresponds to Figure 6.

[0071] As shown in Figure 10, each electrode plate 401b (positive electrode plate 410b and negative electrode plate 420b) has multiple protrusions 480b evenly distributed throughout. Therefore, the area occupied per unit area of ​​the protrusions 480b in the turned section 402b is equal to the area occupied per unit area of ​​the protrusions 480b in the flat section 403b. In this way, since the area occupied by the protrusions 480b in the turned section 402b is equal to the area occupied by the protrusions 480b in the flat section 403b, the protrusions 480b can be formed evenly across the entire electrode plate 401b. Thus, an electrode body 400b equipped with protrusions 480b can be easily manufactured.

[0072] [Difference 3] In the above embodiment, an electrode body 400 having a semicircular turn portion 402 was illustrated. However, the shape of the turn portion 402 can be anything. This modified example 3 describes an example of another shape of the turn portion. Figure 11 is a partial cross-sectional view of a part of the electrode body 400c near the turn portion 402c according to modified example 3. Figure 11 corresponds to Figure 6. As shown in Figure 11, the turn portion 402c of the electrode body 400c has a shape that is flattened in the Z-axis direction from a semicircular shape.

[0073] (others) The above describes a method for manufacturing an energy storage element according to embodiments of the present invention (including its modifications; the same applies hereinafter). However, the present invention is not limited to the above embodiments. The embodiments disclosed herein are illustrative in all respects, and the scope of the present invention includes all modifications in the sense and scope equivalent to the claims. Configurations constructed by arbitrarily combining the components included in the above embodiments and their modifications are also included within the scope of the present invention.

[0074] In the above embodiment, the example shown is that the electrode body 400 is housed in the container 100 with the winding axis W parallel to the X-axis direction. However, the electrode body 400 may also be housed in the container 100 with the winding axis W parallel to the Z-axis direction.

[0075] In the above embodiment, as shown in Figure 6, the example is shown in which the protrusions 480 of each layer are stacked in the radial direction of the turn portion 402. However, the protrusions 480 of each layer may be arranged with a circumferential offset in the circumferential direction of the turn portion 402. [Industrial applicability]

[0076] This invention can be applied to methods for manufacturing energy storage elements such as lithium-ion secondary batteries. [Explanation of Symbols]

[0077] 10 Energy storage elements 100 containers 110 Container body 111 Bottom wall 112 First wall (wall) 113 Second wall 120 Lid 200 terminals 300 Current collector 400, 400a, 400b, 400c electrode bodies 401, 401b plate 402, 402a, 402b, 402c Turn section 403, 403b flat part 409 Slit 410, 410b positive electrode plate 411, 421 Current collector foil 414, 424 Active material layer 415, 425 forming part 416, 426 Non-formed part 420, 420a, 420b negative electrode plate 430 Separator 456 Positive electrode connection 466 Negative electrode connection 480, 480b, 480c convex part 481 recess 500 Manufacturing equipment 510 Assembly Department 520 Storage Unit 530 Container weld 540 Injection section 545 Compression area 546 Gripping part 550 Live part 560 Control Unit W winding shaft Y10 Dashed arrow

Claims

1. A method for manufacturing an energy storage element comprising an electrode body around which electrode plates are wound, and a container for housing the electrode body, The electrode plate has a forming portion on which an active material layer is formed, The electrode body comprises a pair of turned portions and a flat portion connecting the pair of turned portions. The forming portion includes a protrusion that protrudes in the thickness direction of the electrode plate, The aforementioned protrusion is located at least on the turn portion, The aforementioned manufacturing method is The electrode body is housed in the container in a position in which the flat portion is sandwiched between a pair of walls facing each other, This includes charging the energy storage element while the pair of walls are compressed in opposing directions. A method for manufacturing energy storage elements.

2. The area occupied per unit area of ​​the protrusion in the turn portion is larger than the area occupied per unit area of ​​the protrusion in the flat portion. A method for manufacturing an energy storage element according to claim 1.

3. The area occupied by the protrusion in the flat portion is zero. A method for manufacturing an energy storage element according to claim 2.

4. The area occupied per unit area of ​​the protrusion in the turn portion is equivalent to the area occupied per unit area of ​​the protrusion in the flat portion. A method for manufacturing an energy storage element according to claim 1.

5. The aforementioned electrode plate comprises a positive electrode plate and a negative electrode plate. The protrusions are formed on the formed portion of the positive electrode plate and on the formed portion of the negative electrode plate. A method for manufacturing an energy storage element according to any one of claims 1 to 4.

6. A manufacturing apparatus for an energy storage element comprising an electrode body in which electrode plates are wound, and a container for housing the electrode body, The electrode plate has a forming portion on which an active material layer is formed, The electrode body comprises a pair of turned portions and a flat portion connecting the pair of turned portions. The forming portion includes a protrusion that protrudes in the thickness direction of the electrode plate, The aforementioned protrusion is located at least on the turn portion, The aforementioned manufacturing apparatus, The container comprises a housing section in which the electrode body is housed in the container in a position where the flat portion is sandwiched between a pair of walls facing each other, A compression section that compresses the pair of wall sections in opposing directions, The system includes a charging unit that charges the energy storage element while the pair of wall portions are compressed by the compression portion, Manufacturing equipment for energy storage elements.

Images