Manufacturing method for energy storage elements

Abstract

The present invention provides a method for manufacturing energy storage elements that can improve the manufacturability of elongated cylindrical energy storage elements. [Solution] A method for manufacturing an energy storage element comprising an electrode body and a container for housing the electrode body includes stacking a plurality of electrode plates and separators and winding them into a cylindrical shape to form a cylindrical electrode body 750, inserting the cylindrical electrode body into a cylindrical body 780, and compressing the cylindrical body and the cylindrical electrode body to deform the cylindrical body into the container body and the cylindrical electrode body into an electrode body.

Description

Technical Field

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

Background Art

[0002] Conventionally, a single battery manufactured by inserting a wound group wound in a flat shape into a long cylindrical battery can is known (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, there has been a demand for improving the manufacturability of long cylindrical power storage elements.

[0005] For this reason, an object of the present invention is to provide a method for manufacturing a power storage element capable of improving the manufacturability of a long cylindrical power storage element.

Means for Solving the Problems

[0006] [[ID=]] 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 and a container for housing the electrode body, wherein the electrode body comprises a pair of curved portions and a flat portion sandwiched between the curved portions, the container comprises a cylindrical container body and a pair of lids that close both ends of the container body, the container body comprises a pair of curved wall portions facing the pair of curved portions of the electrode body and a pair of flat wall portions facing each other across the flat portion, and the manufacturing method includes stacking a plurality of electrode plates and separators and winding them into a cylindrical shape to form a cylindrical electrode body, inserting the cylindrical electrode body into the cylindrical body, and compressing the cylindrical body and the cylindrical electrode body to deform the cylindrical body into the container body and the cylindrical electrode body into the electrode body. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a method for manufacturing an energy storage element that can improve the manufacturability of the elongated cylindrical energy storage element. [Brief explanation of the drawing]

[0008] [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 an exploded perspective view showing the individual components of the energy storage element according to the embodiment. [Figure 3] Figure 3 is an explanatory diagram showing a winding device for manufacturing a cylindrical electrode body according to an embodiment. [Figure 4] Figure 4 is an explanatory diagram showing the state before the insertion process according to the embodiment. [Figure 5] Figure 5 is an explanatory diagram showing the state after the insertion process according to the embodiment. [Figure 6] Figure 6 is an explanatory diagram showing the deformation process according to the embodiment. [Figure 7] Figure 7 is a perspective view showing the electrode body according to Modified Example 1. [Figure 8] Figure 8 is a perspective view showing the energy storage element according to Modification 2. [Figure 9]Figure 9 is an explanatory diagram showing an energy storage device equipped with an energy storage element according to an embodiment. [Modes for carrying out the invention]

[0009] (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 and a container for housing the electrode body, wherein the electrode body comprises a pair of curved portions and a flat portion sandwiched between the curved portions, the container comprises a cylindrical container body and a pair of lids that close both ends of the container body, the container body comprises a pair of curved wall portions facing the pair of curved portions of the electrode body and a pair of flat wall portions facing each other across the flat portion, and the manufacturing method comprises stacking a plurality of electrode plates and separators and winding them into a cylindrical shape to form a cylindrical electrode body, inserting the cylindrical electrode body into the cylindrical body, and compressing the cylindrical body and the cylindrical electrode body to deform the cylindrical body into the container body and the cylindrical electrode body into the electrode body.

[0010] In the method for manufacturing an energy storage element described in (1) above, compared to inserting an electrode body having a pair of curved portions and a flat portion into a container body having a pair of curved wall portions and a pair of flat wall portions, inserting a cylindrical electrode body into a cylindrical body as in this embodiment allows for smoother insertion and is preferable from the viewpoint of manufacturability. Furthermore, compared to winding multiple electrode plates in a flattened manner, winding multiple electrode plates and separators stacked and cylindrical as in this embodiment allows for a faster winding speed. In these respects, it is possible to improve the manufacturability of the energy storage element.

[0011] (2) In the method for manufacturing the energy storage element described in (1) above, the cylindrical body is deformed into the container body and the cylindrical electrode body is deformed into the electrode body, so that the outer surface of the cylindrical electrode body is in contact with the inner surface of the cylindrical body around its entire circumference even before compression.

[0012] According to the method for manufacturing a power storage element described in (2) above, since the outer surface of the cylindrical electrode body contacts the inner surface of the cylindrical body over the entire circumference before compression, even after compression, the inner surface of the container and the outer surface of the electrode body contact each other over the entire circumference. For this reason, the electrode body is pressed against the inner surface of the container over the entire circumference, making it difficult for gaps to be formed between the layers of the electrode body. By suppressing the gaps, a decrease in energy density can be suppressed.

[0013] (3) In the method for manufacturing a power storage element described in (1) or (2) above, in forming the cylindrical electrode body, it may be such that a core having elasticity is used as a winding core, and the plurality of electrode plates and the separator are wound.

[0014] According to the method for manufacturing a power storage element described in (3) above, since a core having elasticity is used as the winding core, stress is generated from the inside of the electrode body due to the elasticity of the core. By this stress, the gaps between the layers can be suppressed, and a decrease in energy density can be further suppressed.

[0015] (4) In the method for manufacturing a power storage element described in any one of (1) to (3) above, after deforming the cylindrical body into the container body and deforming the cylindrical electrode body into the electrode body, it may include welding the pair of lid bodies to both ends of the container body.

[0016] According to the method for manufacturing a power storage element described in (4) above, after the cylindrical body is deformed into the container body and the cylindrical electrode body is deformed into the electrode body, the lid bodies are welded to both ends of the container body, so the deformation of the cylindrical body and the cylindrical electrode body is not hindered by the lid bodies. For this reason, the cylindrical body and the cylindrical electrode body can be deformed smoothly.

[0017] (5) In the method for manufacturing an energy storage element according to any one of (1) to (4) above, when the electrode body after compression deformation is viewed from the stacking direction at the flat portion, it has a shape based on a rectangle, and at least one corner portion is a first notch portion that is chamfered, and the container has a shape based on a rectangle when viewed from the stacking direction, and a corner portion corresponding to the first notch portion is a second notch portion that is chamfered, which may be adopted.

[0018] According to the method for manufacturing an energy storage element according to (5) above, it is also possible to improve the manufacturability for an electrode body having a first notch portion and a container having a second notch portion.

[0019] (Embodiment) Hereinafter, an energy storage element according to an embodiment (including a modified example thereof) of the present invention will be described with reference to the drawings. Each of the embodiments described below shows comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement positions and connection forms of the components, manufacturing processes, order of manufacturing processes, etc. shown in the following embodiments are examples and are not intended to limit the present invention. In each figure, dimensions and the like are not strictly illustrated. In each figure, the same or similar components are denoted by the same reference numerals. The names of the constituent members (each component) of the present embodiment are those in the present embodiment and may be different from the names of the constituent members (each component) in the background art.

[0020] In the following description and drawings, at least one of the longitudinal direction of the energy storage element and the winding axis direction of the electrode body provided in the energy storage element is defined as the X-axis direction. At least one of the thickness direction of the container of the energy storage element and the facing direction of the pair of flat wall portions of the container is defined as the Y-axis direction. At least one of the facing direction of the pair of curved portions of the electrode body and the facing direction of the pair of curved wall portions of the container is defined as the Z-axis direction. These X-axis direction, Y-axis direction and Z-axis direction are directions that intersect (orthogonal in the present embodiment) with each other. Although the Z-axis direction may not be the vertical direction depending on the usage mode, hereinafter, for the sake of convenience of explanation, the Z-axis direction will be described as the vertical direction.

[0021] In the following explanation, 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. Furthermore, expressions indicating relative directions or orientations, such as parallel and orthogonal, include cases where the direction or orientation is not strictly accurate. Two directions being orthogonal does not only mean that the two directions are perfectly orthogonal, but also that they are substantially orthogonal, meaning that there may be a difference of a few percent.

[0022] In the following explanation, "insulation" refers to "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 higher is even more preferable.

[0023] [Energy storage element] Figures 1 and 2 will be used to provide a general explanation of the energy storage element 10 in this embodiment. Figure 1 is a perspective view showing the external appearance of the energy storage element 10 according to this embodiment. Figure 2 is an exploded perspective view showing the individual components of the energy storage element 10 according to this embodiment.

[0024] The energy storage element 10 is a secondary battery (single cell) capable of charging and discharging electricity, and 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), aircraft, 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.

[0025] 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 be a primary battery instead of a secondary battery. Furthermore, the energy storage element 10 may be a battery using a solid electrolyte.

[0026] As shown in Figures 1 and 2, the energy storage element 10 comprises a container 100, a pair of terminals 300, and a pair of external gaskets 400. Furthermore, the energy storage element 10 comprises a pair of internal gaskets 500, a pair of current collectors 600, and an electrode body 700 inside the container 100.

[0027] The container 100 contains an electrolyte (non-aqueous electrolyte), but this is not shown in the diagram. The type of electrolyte is not particularly limited as long as it does not impair the performance of the energy storage element 10. In addition to the above components, spacers may be placed to the side, above, or below the electrode body 700, or an insulating film or the like may be placed to enclose the electrode body 700, etc.

[0028] The container 100 is a case with an elongated cylindrical outer shape that is long in the X-axis direction and flattened in the Y-axis direction. In this embodiment, although not particularly limited, from the viewpoint of improving the energy density of the energy storage element 10, the length of the container 100 in the X-axis direction is preferably three times or more the length of the container 100 in the Z-axis direction. Furthermore, it is even more preferable that the length of the container 100 in the X-axis direction is five times or more the length of the container 100 in the Y-axis direction.

[0029] The container 100 comprises a container body 160 and a pair of lids 170. The container body 160 and each lid 170 are assembled to form a long cylindrical container 100 that extends in the X-axis direction. The container body 160 comprises a pair of flat wall sections 131 and a pair of curved wall sections 141. The pair of flat wall sections 131 and the pair of curved wall sections 141 form a long cylindrical shape that extends in the X-axis direction and penetrates through the container. The pair of lids 170 are plate-shaped members that close off each end of the container body 160 in the X-axis direction and are included in the walls of the container 100. The lid 170 located in the negative X-axis direction closes off the end of the container body 160 in the negative X-axis direction, and the lid 170 located in the positive X-axis direction closes off the end of the container body 160 in the positive X-axis direction.

[0030] A gas release valve 173 is provided on at least one of the pair of lids 170. Specifically, the gas release valve 173 is located at the end of the lid 170 in the negative Z-axis direction. The gas release valve 173 is a safety valve that releases pressure when the pressure inside the container 100 rises excessively.

[0031] At least one of the pair of lids 170 has a liquid injection section 171 at the end in the positive X-axis direction and in the center in the Z-axis direction. The liquid injection section 171 is a part for injecting electrolyte into the container 100 during manufacturing, and is sealed after injection.

[0032] With this configuration, the container 100 is structured such that after the electrode body 700 and the like are housed inside the container body 160, the container body 160 and the lid 170 are joined by welding or the like to seal the inside. The material of the container 100 (container body 160 and lid 170) is not particularly limited, but weldable metals such as stainless steel, aluminum, aluminum alloy, iron, and plated steel sheet are preferred. In this disclosure, after the electrode body 700 and the like are housed inside the container body 160, the container body 160 is compressed / deformed by press working, so the material of the container 100 needs to have formability suitable for compression / deformation.

[0033] Each of the pair of curved wall portions 141 is elongated in the X-axis direction and faces the curved portion 711 of the electrode body 700. In other words, each of the pair of curved wall portions 141 faces the pair of curved portions 711. The inner surface of each curved wall portion 141 is curved to follow the curved portion 711 of the electrode body 700. Specifically, the inner surface of the curved wall portion 141 located in the Z-axis positive direction is curved so as to be concave in the Z-axis positive direction when viewed in the X-axis direction, and the inner surface of the curved wall portion 141 located in the Z-axis negative direction is curved so as to be concave in the Z-axis negative direction when viewed in the X-axis direction. In this embodiment, the outer surface of each curved wall portion 141 is also curved. Specifically, the curved wall portion 141 located in the Z-axis positive direction is formed in a curved plate shape that protrudes in the Z-axis positive direction when viewed in the X-axis direction. On the other hand, the curved wall portion 141 in the Z-axis negative direction is formed in a curved plate shape that protrudes in the Z-axis negative direction when viewed in the X-axis direction. Each of the pair of flat wall portions 131 is elongated in the X-axis direction and is a wall portion that faces the flat portion 712 of the electrode body 700 in the Y-axis direction. In other words, each of the flat wall portions 131 faces both sides of the flat portion 712. Each flat wall portion 131 is formed in a flat plate shape parallel to the XZ plane, and the inner surface of the flat wall portion 131 is flat so as to conform to the flat portion 712 of the electrode body 700.

[0034] Terminals 300 are terminals (positive and negative terminals) that are electrically connected to the electrode body 700 via the current collector 600. In other words, terminals 300 are metal components that lead the electricity stored in the electrode body 700 to the external space of the energy storage element 10, or introduce electricity into the internal space of the energy storage element 10 in order to store electricity in the electrode body 700. The material of terminals 300 is not particularly limited, but terminals 300 are made of conductive material such as aluminum, aluminum alloy, copper, or copper alloy. Terminals 300 are connected (joined) to the current collector 600 by crimping, welding, etc., and are attached to the cover body 170.

[0035] Each terminal 300 is attached to each cover 170. Specifically, each terminal 300 comprises a terminal body portion 330 and a shaft portion 340 protruding from the terminal body portion 330. The terminal body portion 330 is the part that protrudes outward from the cover 170. Each cover 170 has a through hole 172 through which the shaft portion 340 passes. The terminal 300 and the current collector 600 are connected (joined) by crimping the shaft portion 340 through the cover 170, the outer gasket 400, the inner gasket 500, and the current collector 600.

[0036] The current collectors 600 are positioned one at each end of the electrode body 700 in the X-axis direction. The current collectors 600 are conductive members (positive electrode current collector and negative electrode current collector) that are connected (joined) to the electrode body 700 and the terminal 300, thereby electrically connecting the electrode body 700 and the terminal 300. The current collector 600 integrally includes a first joint portion 630 and a second joint portion 640. Specifically, the first joint portion 630 of the current collector 600 and the nine portion 720 of the electrode body 700 (described later) are connected (joined) by welding or crimping, and the second joint portion 640 of the current collector 600 and the terminal 300 are connected (joined) by crimping or welding. The first joint portion 630 and the second joint portion 640 are each flat plate-shaped parts, formed by bending a single sheet of metal. The material of the current collector 600 is not particularly limited, but in this embodiment, the positive electrode current collector is made of a conductive material such as aluminum or an aluminum alloy, and the negative electrode current collector is made of a conductive material such as copper or a copper alloy.

[0037] The external gasket 400 is positioned between the lid 170 and the terminal 300, insulating the space between the lid 170 and the terminal 300, and sealing the inside of the container 100. The internal gasket 500 is positioned between the lid 170 and the current collector 600, insulating the space between the lid 170 and the current collector 600, and sealing the inside of the container 100. In this embodiment, both the external gasket 400 and the internal gasket 500 are plate-shaped and rectangular insulating members. The material of the external gasket 400 and the internal gasket 500 may be polypropylene (PP), polyethylene (PE), polystyrene (PS), ABS resin, or composite materials thereof, or other resins having electrical insulating properties.

[0038] The electrode body 700 is an energy storage element (power generation element) formed by winding electrode plates. The electrode body 700 includes a long cylindrical shape extending in the X-axis direction. In this embodiment, the length of the electrode body 700 in the Y-axis direction is shorter than the length of the electrode body 700 in the X-axis direction and the length in the Z-axis direction, so the electrode body 700 has a flattened shape in the Y-axis direction. Although not particularly limited, the length of the electrode body 700 in the X-axis direction may be 300 mm or more, specifically about 500 mm to 1500 mm. The length of the electrode body 700 in the X-axis direction is longer than the length of the electrode body 700 in the Z-axis direction, and the length of the electrode body 700 in the X-axis direction is three times or more the length of the electrode body 700 in the Z-axis direction. The electrode body 700 comprises a main body portion 710 and a plurality of tab portions 720 (positive electrode tab portion 721 and negative electrode tab portion 722) protruding from the main body portion 710, and as described above, the tab portions 720 and the current collector 600 are connected (joined).

[0039] The main body portion 710 is an elliptical or oblong cylindrical portion formed by winding the electrode plates and separators. The main body portion 710 comprises a pair of curved portions 711 and a flat portion 712 sandwiched between the pair of curved portions 711. Each of the pair of flat portions 712 is located between the pair of curved portions 711 in the Z-axis direction, and the overall shape is flat. It can also be said that the pair of curved portions 711 are positioned to sandwich each of the flat portions 712 in the Z-axis direction.

[0040] The curved portion 711 extends in the X-axis direction and protrudes in either the positive or negative Z-axis direction. Viewed from the X-axis direction, the curved portion 711 is curved in a semicircular arc shape (curved shape). The curved portion 711 located in the positive Z-axis direction and the curved wall portion 141 of the container body 160 located in the positive Z-axis direction directly face each other in the Z-axis direction, and the curved portion 711 located in the negative Z-axis direction and the curved wall portion 141 of the container body 160 located in the negative Z-axis direction directly face each other in the Z-axis direction. In other words, the curved portion 711 and the curved wall portion 141 face each other in the Z-axis direction at the upper and lower parts of the energy storage element 10.

[0041] The flat section 712 extends in the X-axis direction and is a flat-shaped portion parallel to the XZ plane that connects the ends of the pair of curved sections 711. The flat section 712 is positioned opposite each flat wall section 131 of the container body 160. In the flat section 712, multiple wound electrode plates are stacked in the Y-axis direction. In this description, the main stacking direction of the multiple electrode plates is defined as the Y-axis direction.

[0042] The curved shape of the curved portion 711, as viewed from the X-axis direction, is not limited to a semicircular arc shape, but may also be a shape like part of an ellipse, or a shape with rounded corners like a square. The outer surface of the flat portion 712 is not limited to being perfectly flat, and may be slightly concave or slightly convex.

[0043] Multiple tab portions 720 protrude one by one from both end faces of the main body portion 710 in the X-axis direction. A positive electrode tab portion 721 is provided on one end face of the main body portion 710 in the X-positive direction, and a negative electrode tab portion 722 is provided on the other end face of the main body portion 710 in the X-negative direction.

[0044] [Manufacturing method for energy storage elements] Next, the manufacturing method of the energy storage element 10 will be described. First, a cylindrical electrode body 750, which will become the electrode body 700, is formed. Figure 3 is an explanatory diagram showing a winding device 900 for manufacturing the cylindrical electrode body 750 according to the embodiment. As shown in Figure 3, the winding device 900 includes a first roll body holding section 910, a second roll body holding section 920, a third roll body holding section 930, a fourth roll body holding section 940, a pair of rollers 950, and a winding section 960.

[0045] The first roll body holding section 910 rotatably holds the positive electrode roll 911. The positive electrode roll 911 is a roll body in which a strip-shaped positive electrode base material 912, which will become the positive electrode plate (electrode plate), is wound into a roll shape.

[0046] The positive electrode substrate 912 has a positive electrode active material layer (shown as dot hatching in Figure 3) formed on at least one of the front and back surfaces of the current collector foil, which is a metal foil. Of the pair of long sides of the positive electrode substrate 912, a plurality of positive electrode tabs 913, which constitute the positive electrode tab portion 721, protrude from one of the long sides. The plurality of positive electrode tabs 913 are arranged at predetermined intervals along the long side. Each positive electrode tab 913 is a portion where the positive electrode active material layer is not formed and the current collector foil is exposed.

[0047] The positive electrode current collector foil is made of aluminum or an aluminum alloy. The positive electrode active material layer includes a positive electrode active material, a binder, and a conductive material. As the positive electrode active material, any known material capable of intercalating and deintercalating charge transport ions can be used.

[0048] The second roll body holding section 920 is located directly below the first roll body holding section 910. The second roll body holding section 920 rotatably holds the separator roll 921. The separator roll 921 is a roll body in which a strip-shaped separator base material 922, which serves as a separator, is wound into a roll shape.

[0049] The third roll body holding section 930 is located directly below the second roll body holding section 920. The third roll body holding section 930 rotatably holds the negative electrode roll 931. The negative electrode roll 931 is a roll body in which a strip-shaped negative electrode base material 932, which will become the negative electrode plate (electrode plate), is wound into a roll shape.

[0050] The negative electrode substrate 932 has a negative electrode active material layer (shown as dot hatching in Figure 3) formed on at least one of the front and back surfaces of the current collector foil, which is a metal foil. Of the pair of long sides of the negative electrode substrate 932, a plurality of negative electrode tabs 933, which constitute the negative electrode tab portion 722, protrude from the other long side. The plurality of negative electrode tabs 933 are arranged at predetermined intervals along the long side. Each negative electrode tab 933 is a portion where the negative electrode active material layer is not formed and the current collector foil is exposed.

[0051] Copper or a copper alloy is used for the negative electrode current collector foil. The negative electrode active material layer contains a negative electrode active material, a binder, and a thickener. As the negative electrode active material, any known material that can intercept and deintercept charge transport ions can be used.

[0052] The fourth roll body holding section 940 is located directly below the third roll body holding section 930. The fourth roll body holding section 940 rotatably holds the separator roll 941. The separator roll 941 is a roll body in which a strip-shaped separator base material 942, which serves as a separator, is wound into a roll shape.

[0053] The pair of rollers 950 are the parts that laminate the positive electrode base material 912, separator base material 922, negative electrode base material 932, and separator base material 942. In this embodiment, the pair of rollers 950 are positioned in front of the third roll body holding section 930. The pair of rollers 950 are drawn out from the first roll body holding section 910, the second roll body holding section 920, the third roll body holding section 930, and the fourth roll body holding section 940, respectively, and sandwich and laminate the stacked positive electrode base material 912, separator base material 922, negative electrode base material 932, and separator base material 942.

[0054] The winding section 960 is the part that winds the stacked positive electrode base material 912, separator base material 922, negative electrode base material 932, and separator base material 942 into a cylindrical shape. In this embodiment, the winding section 960 is positioned in front of a pair of rollers 950. The winding section 960 winds the positive electrode base material 912, separator base material 922, negative electrode base material 932, and separator base material 942 around an elastic core body 770. After winding, the positive electrode base material 912, separator base material 922, negative electrode base material 932, and separator base material 942 are cut by a cutting device (not shown) to form a cylindrical electrode body 750 (see Figure 4). The cylindrical electrode body 750 comprises a positive electrode plate, a negative electrode plate, and a pair of separators. In this manner, the winding device 900 stacks multiple electrode plates and separators and winds them into a cylindrical shape to form a cylindrical electrode body 750. At one end of the cylindrical electrode body 750, a positive electrode tab portion 721 is formed by stacking multiple positive electrode tabs 913, and at the other end, a negative electrode tab portion 722 is formed by stacking multiple negative electrode tabs 933 (see Figure 4).

[0055] Next, in the manufacturing process, the cylindrical electrode body 750 is inserted into the cylindrical body 780 (insertion step). Figure 4 is an explanatory diagram showing the state before the insertion step according to the embodiment, and Figure 5 is an explanatory diagram showing the state after the insertion step according to the embodiment.

[0056] As shown in Figure 4, in the insertion step, a cylindrical body 780 is prepared. The cylindrical body 780 is a cylindrical metal member that will become the container body 160. In the insertion step, the cylindrical electrode body 750 is inserted into the cylindrical body 780. As shown in Figure 5, at least a portion of the positive electrode tab portion 721 and the negative electrode tab portion 722 of the cylindrical electrode body 750 protrude from the cylindrical body 780.

[0057] In this case, during insertion, the cylindrical electrode body 750 may be inserted into the cylindrical body 780 while tightly wound to a size smaller than the inner diameter of the cylindrical body 780, and after insertion, the tightness may be released to expand the cylindrical electrode body 750. This causes the outer surface of the cylindrical electrode body 750 to contact the inner surface of the cylindrical body 780 around its entire circumference. The cylindrical electrode body 750 may be equipped with a separator at its outermost circumference, or it may be covered with an insulating sheet. Even when covered with an insulating sheet, it is possible to bring the outer surface of the cylindrical electrode body 750 into contact with the inner surface of the cylindrical body 780 around its entire circumference via the insulating sheet.

[0058] Next, in the manufacturing process, the cylindrical body 780 and the cylindrical electrode body 750 are compressed to deform the cylindrical body 780 into the container body 160 and the cylindrical electrode body 750 into the electrode body 700 (deformation step).

[0059] Figure 6 is an explanatory diagram showing the deformation process according to the embodiment. Figure 6(a) shows the state immediately after the cylindrical body 780 and the cylindrical electrode body 750 are set in the mold provided in the press machine 800, and Figure 6(b) shows the state after deformation. Figure 6 shows the cylindrical body 780 and the cylindrical electrode body 750 in cross-sectional view.

[0060] As shown in Figure 6(a), a cylindrical body 780 and a cylindrical electrode body 750 are installed on the lower die 810 provided on the press machine 800. Specifically, the cylindrical body 780 and the cylindrical electrode body 750 are positioned on their sides so that their axial directions are aligned with the lower die 810. As a result, the cylindrical body 780 and the cylindrical electrode body 750 are sandwiched radially between the lower die 810 and the upper die 820.

[0061] Next, as shown in Figure 6(b), as the upper die 820 descends, the cylindrical body 780, the cylindrical electrode body 750, and the core body 770 are compressed radially and deformed into a flattened shape. Due to this deformation, the cylindrical body 780 becomes the container body 160, and the cylindrical electrode body 750 becomes the electrode body 700. During deformation, the elastic core body 770 remains inside the electrode body 700 (cylindrical electrode body 750) as a winding core, so stress is generated from inside the electrode body 700 due to the elasticity of the core body 770. This stress can suppress the gap between layers of the electrode body 700. In this embodiment, a method of compression / deformation in a single press is shown using flat plates for the upper die 820 and lower die 810, but the present invention is not limited to this, and more precise processing can be achieved by performing multi-stage pressing using molds of any shape and pressing multiple times.

[0062] The core body 770 is not particularly limited as long as it is elastic and does not dissolve in the container 100, but in this embodiment, it is preferable that it is in a foam form that holds an electrolyte solution inside and can supply the electrolyte solution to the electrode body 700 at the end of the lifespan of the energy storage element 10. In this embodiment, the core body 770 is a foam having a foam structure (sponge-like porous body) made of polyolefin resin such as PE or PP. In order to obtain a large elastic force, it is preferable that the volume occupancy rate of the constituent material (the ratio of the volume excluding space to the volume including space inside the material) of the core body 770 is 80% or less. The core body 770 is made of a material that is at least more elastic than the separator (at least has a lower modulus of elasticity than the separator). Preferably, the core body 770 has a modulus of elasticity of 0.21 to 0.048 MPa, and more preferably, a modulus of elasticity of 0.12 to 0.048 MPa.

[0063] Next, the current collectors 600 are connected to the positive electrode tab portion 721 and the negative electrode tab portion 722. Then, with the terminals 300 connected to each current collector 600 via the internal gasket 500, the lid 170, and the external gasket 400, each lid 170 is welded to both ends of the container body 160. Finally, the electrolyte is injected into the container 100 from the liquid injection portion 171, and the liquid injection portion 171 is closed. This completes the energy storage element 10.

[0064] [Explanation of effects] Compared to inserting an electrode body 700, which has a pair of curved portions 711 and a flat portion 712, into a container body 160, which has a pair of curved wall portions 141 and a pair of flat wall portions 131, inserting the cylindrical electrode body 750 into the cylindrical body 780 as in this embodiment allows for smoother insertion and is preferable from the viewpoint of manufacturability. Furthermore, compared to winding the positive electrode substrate, negative electrode substrate and a pair of separator substrates in a flattened manner, winding the positive electrode substrate 912 (positive electrode plate), negative electrode substrate 932 (negative electrode plate), and a pair of separator substrates 922, 942 (separators) in a cylindrical shape by stacking them as in this embodiment allows for a faster winding speed. In these respects, it is possible to improve the manufacturability of the energy storage element 10.

[0065] Since the outer surface of the cylindrical electrode body 750 is in contact with the inner surface of the cylindrical body 780 over its entire circumference even before compression, the inner surface of the container body 160 and the outer surface of the electrode body 700 remain in contact over their entire circumference even after compression. As a result, the electrode body 700 is compressed over its entire circumference by the inner surface of the container body 160, making it difficult for gaps to form between the layers of the electrode body 700. By suppressing gaps, the decrease in energy density can be suppressed.

[0066] Since the core material 770, which has elasticity, is used as the core of the winding, stress is generated from within the electrode material 700 due to the elasticity of the core material 770. This stress can suppress the gaps between layers, and further suppress the decrease in energy density.

[0067] Since the cylindrical body 780 is deformed into the container body 160 and the cylindrical electrode body 750 is deformed into the electrode body 700, and then the lid 170 is welded to both ends of the container body 160, the lid 170 does not hinder the deformation of the cylindrical body 780 and the cylindrical electrode body 750. Therefore, the cylindrical body 780 and the cylindrical electrode body 750 can be deformed smoothly.

[0068] [Explanation of variations] 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.

[0069] (Variation 1) An electrode body 700a according to Modification 1 will now be described. Figure 7 is a perspective view showing an electrode body 700a according to Modification 1. In the above embodiment, an electrode body 700 having a positive electrode tab portion 721 at one end and a negative electrode tab portion 722 at the other end was exemplified. However, as shown in Figure 7, an electrode body 700a may also exist in which one end 731a and the other end 732a are not formed in a tab shape. Specifically, at each of the one end 731a and the other end 732a of the electrode body 700a, the current collector foil is continuously exposed around the entire circumference, forming a connection portion to which each current collector is connected. Furthermore, even with such an electrode body 700a, each current collector 600 may be joined only to a part of the exposed current collector foil, as in Figure 2.

[0070] (Modification 2) A modified example of the energy storage element 10b according to Modification 2 will now be described. Figure 8 is a perspective view showing the energy storage element 10b according to Modification 2. As shown in Figure 8, the electrode body 700b of the energy storage element 10b has a rectangular shape when viewed from the stacking direction (Y-axis direction), and each of the two corners in the negative Z-axis direction is cut out in a chamfered manner, forming a first notch 735b. On the other hand, the container 100b of the energy storage element 10b has a rectangular shape when viewed from the stacking direction, and the two corners corresponding to each first notch 735b are cut out in a chamfered manner, forming a second notch 135b. The number of first notches 735b and second notches 135b can be any number, as long as there is one or more. A gas discharge valve 173b may be provided in at least one of the two second notches 135b. In this case, the space formed by the second notch 135b can be used as a passage for the gas discharged from the gas discharge valve 173b.

[0071] During the manufacturing of this energy storage element 10b, the cylindrical body 780 and cylindrical electrode body 750 (container body 160 and electrode body 700) that have been deformed in the above deformation process may be cut so as to form the first notch 735b and the second notch 135b.

[0072] In addition to the above, a cylindrical body is prepared in which a recess is formed at the location corresponding to the first notch. Furthermore, a positive electrode substrate, a negative electrode substrate, and a pair of separator substrates, each with a recess formed at the location corresponding to the second notch, are wound together to prepare a cylindrical electrode body. The deformation process may be performed after inserting the cylindrical electrode body with the recess into the cylindrical body with the recess. In this case, since there is no cutting after insertion, contamination can be suppressed.

[0073] Thus, it is possible to improve manufacturability even for the electrode body 700b having the first notch 735b and the container 100b having the second notch 135b.

[0074] (Other variations) The above describes a method for manufacturing an energy storage element according to embodiments of the present invention (including modifications thereof; 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.

[0075] In the above embodiment, the example was given in which the outer surface of the cylindrical electrode body 750 is in contact with the inner surface of the cylindrical body 780 over its entire circumference before compression. However, a portion of the outer surface of the cylindrical electrode body may be separated from the inner surface of the cylindrical body.

[0076] In the above embodiment, an example was given in which an elastic core 770 is used as the winding core, but the winding core may be withdrawn from the cylindrical electrode body 750 after winding.

[0077] The energy storage elements of the above embodiments may be used in an energy storage device. In this case, the technology of the present invention only needs to be applied to at least one energy storage element in the energy storage device. Figure 9 is an explanatory diagram showing an energy storage device equipped with energy storage elements according to an embodiment. As shown in Figure 9, a plurality of energy storage elements 10 are arranged inside the energy storage device 20. The energy storage device 20 may include busbars (not shown) that electrically connect each energy storage element 10. The energy storage device 20 may also include a state monitoring device (not shown) that monitors the state of one or more energy storage elements 10.

[0078] The present invention also includes forms constructed by arbitrarily combining the components included in the above embodiments and their modified examples. [Industrial applicability]

[0079] This invention can be applied to a method for manufacturing energy storage elements such as lithium-ion secondary batteries. [Explanation of Symbols]

[0080] 10, 10b Energy storage element 20 Energy storage devices 100, 100b container 131 Flat wall section 135b Second notch 141 Curved wall section 160 Container body 170 Lid 300 terminals 400 External gasket 500 Internal Gasket 600 Current collector 700, 700a, 700b electrode body 710 Main Unit 711 Curved section 712 Flat area 720 Tab section 721 Positive electrode tab section 722 Negative electrode tab section 731a One end 732a Other end 735b First cutout 750 cylindrical electrode body 770 Core body 780 Cylindrical body 912 Positive electrode substrate 913 Positive Tab 933 Negative Electrode Tab 922, 942 Separator substrate

Claims

1. A method for manufacturing an energy storage element comprising an electrode body and a container for housing the electrode body, The electrode body comprises a pair of curved portions and a flat portion sandwiched between the curved portions, The container comprises a cylindrical container body and a pair of lids that close both ends of the container body. The container body is A pair of curved wall portions facing the pair of curved portions of the electrode body, It comprises a pair of flat wall portions facing each other, with the aforementioned flat portion in between. The aforementioned manufacturing method is Multiple electrode plates and separators are stacked and wound into a cylindrical shape to form a cylindrical electrode body, Inserting the cylindrical electrode into the cylindrical body, This includes compressing the cylindrical body and the cylindrical electrode body to deform the cylindrical body into the container body and the cylindrical electrode body into the electrode body, A method for manufacturing energy storage elements.

2. By deforming the cylindrical body into the container body and the cylindrical electrode body into the electrode body, the outer surface of the cylindrical electrode body is in contact with the inner surface of the cylindrical body around its entire circumference even before compression. A method for manufacturing an energy storage element according to claim 1.

3. In forming the cylindrical electrode body, an elastic core is used as the winding core, and the plurality of electrode plates and the separator are wound around it. A method for manufacturing an energy storage element according to claim 1 or 2.

4. This includes, after deforming the cylindrical body into the container body and the cylindrical electrode body into the electrode body, welding the pair of lids to both ends of the container body, A method for manufacturing an energy storage element according to claim 1 or 2.

5. The electrode body, when viewed from the stacking direction of the electrode plate and the separator in the flat portion, has a rectangular shape, and at least one corner is a chamfered cut-out portion. The container, when viewed from the stacking direction, has a rectangular shape, and the corners corresponding to the aforementioned cutouts are chamfered to form second cutouts. A method for manufacturing an energy storage element according to claim 1 or 2.

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