Non-aqueous electrolyte secondary battery and method for manufacturing the same

Abstract

A nonaqueous electrolyte secondary battery includes a first separator, a positive electrode plate, a second separator, and a negative electrode plate, which are overlapped and wound 10 turns or more to form an electrode body. The electrode body has a flat portion in which an outer peripheral surface is flat, and two curved surface portions in which the outer peripheral surfaces are curved, which are arranged at both ends in a first direction of the flat portion. The nonaqueous electrolyte secondary battery includes a winding end tape attached to an outermost peripheral surface of the electrode body, and a positive electrode protection tape adhered to a winding start side end portion on an inner peripheral side of the positive electrode plate. The winding end tape is arranged at one of the two curved surface portions, and the positive electrode protection tape is arranged along the curved surface of the winding start side end portion of the positive electrode plate on one or the other curved surface portion.

Description

Technical Field

[0001] This disclosure relates to non-aqueous electrolyte secondary batteries and methods for manufacturing the same. Background Technology

[0002] In recent years, non-aqueous electrolyte secondary batteries, represented by lithium-ion batteries, have been widely used as secondary batteries that achieve high output and high energy density.

[0003] Patent document 1 describes a square non-aqueous electrolyte secondary battery in which a flat, rolled electrode body, formed by the positive and negative electrode plates being wound together with a separator, is housed in a casing.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2014-56742 Summary of the Invention

[0007] To further improve the energy density of non-aqueous electrolyte secondary batteries, methods to increase the positive electrode density of the positive electrode plate have been considered. However, as the positive electrode density increases, the rigidity of the electrode body increases, leading to poorer formability when forming a flat, rolled electrode body with many turns. This results in larger dimensional deviations, such as thickness, during electrode body manufacturing. This can reduce the productivity of non-aqueous electrolyte secondary batteries. Furthermore, sometimes a winding end strip is fixed at the outermost circumference of the electrode body for stopping the winding. In this case, depending on the position of the winding end strip, the formability of the formed electrode body can sometimes deteriorate, potentially increasing dimensional deviations. Additionally, direct contact between the inner circumference of the positive electrode plate's winding start end and other components such as separators can also lead to poor formability and potentially increased dimensional deviations of the electrode body.

[0008] As one aspect of this disclosure, a non-aqueous electrolyte secondary battery comprises: an electrode body formed by overlapping a first separator, a positive electrode plate, a second separator, and a negative electrode plate such that the first separator or the second separator is sandwiched between the positive electrode plate and the negative electrode plate, and being wound at least 10 turns; the electrode body has a flat portion with a flat outer peripheral surface and two curved portions with curved outer peripheral surfaces disposed at both ends of the flat portion in a first direction; the non-aqueous electrolyte secondary battery comprises: a winding end strip attached to the outermost peripheral surface of the electrode body such that the winding end of the electrode body is fixed to the outermost peripheral surface of the electrode body; and a positive electrode protection strip adhered to the winding start end of the inner peripheral side of the positive electrode plate; the winding end strip is disposed on one of the two curved portions, and the positive electrode protection strip is disposed on one or the other curved portion along the curved surface of the winding start end of the positive electrode plate.

[0009] As one aspect of this disclosure, the method for manufacturing a non-aqueous electrolyte secondary battery includes: a pre-pressing electrode body forming step in which a first separator, a positive electrode body, a second separator, and a negative electrode body are overlapped and wound more than 10 turns in such a way that at least a first separator or a second separator is sandwiched between a positive electrode body and a negative electrode body; and a forming pressing step in which, after the pre-pressing electrode body forming step, the pre-pressing electrode body is pressed in a direction orthogonal to a first direction to form a flat electrode body.

[0010] The non-aqueous electrolyte secondary battery and its manufacturing method disclosed herein can improve the formability of the electrode body by increasing the number of electrode body coils, thereby suppressing dimensional deviations of the electrode body during manufacturing. Attached Figure Description

[0011] Figure 1 This is a cross-sectional view of a non-aqueous electrolyte secondary battery as an example of an implementation method.

[0012] Figure 2 for Figure 1 A top view of a non-aqueous electrolyte secondary battery.

[0013] Figure 3 To constitute Figure 1 In the electrode body of a non-aqueous electrolyte secondary battery, equivalent to Figure 1 A diagram of section AA.

[0014] Figure 4 To show Figure 3 A diagram showing the starting end of the positive electrode plate of the electrode body and the positive electrode protective strip.

[0015] Figure 5 Assume Figure 3 A diagram showing the positional relationship between the ends of the positive and negative electrodes when the starting end of the winding of the negative electrode is located 0.5 layers inside the starting end of the winding of the positive electrode.

[0016] Figure 6 A flowchart illustrating a method for manufacturing a non-aqueous electrolyte secondary battery according to an example of an embodiment.

[0017] Figure 7 A diagram illustrating another example of a positive electrode protective tape adhered to the starting end of the positive electrode plate.

[0018] Figure 8 In the electrode body of the non-aqueous electrolyte secondary battery constituting Comparative Example 1, corresponding to Figure 3 The image.

[0019] Figure 9In the electrode body of the non-aqueous electrolyte secondary battery constituting Comparative Example 2, corresponding to Figure 3 The image.

[0020] Figure 10 In the electrode body of the non-aqueous electrolyte secondary battery constituting Comparative Example 3, corresponding to Figure 3 The image.

[0021] Figure 11 In the electrode body of the non-aqueous electrolyte secondary battery constituting Comparative Example 4, corresponding to Figure 3 The image. Detailed Implementation

[0022] To solve the aforementioned problems, the inventors conducted in-depth research and discovered that an electrode body comprising a first separator, a positive electrode plate, a second separator, and a negative electrode plate, overlapped in such a manner that the first or second separator is sandwiched between the positive and negative electrode plates, and wound at least 10 turns, can improve the formability of the electrode body and suppress dimensional deviations during manufacturing. The electrode body has a flat portion with a flat outer peripheral surface and two curved portions with curved outer peripheral surfaces located at both ends of the flat portion in a first direction. It also includes a winding end strip fixed to the outermost periphery of the electrode body and a positive electrode protective strip adhered to the winding start end of the inner peripheral side of the positive electrode plate. The winding end strip is disposed on one of the two curved portions, and the positive electrode protective strip is disposed on one or the other curved portion along the curved surface of the winding start end of the positive electrode plate. This improves the formability of the electrode body and suppresses dimensional deviations during manufacturing. This will be described in detail below.

[0023] Hereinafter, an example of an embodiment of the present disclosure will be described in detail. In the following description, the specific shapes, materials, directions, values, etc., are examples for the purpose of making the present disclosure easier to understand, and may be appropriately changed according to the use, purpose, specifications, etc. Hereinafter, a square battery in which the wound electrode body is housed in a battery casing that is a square metal casing will be described.

[0024] Figure 1 This is a cross-sectional view of the non-aqueous electrolyte secondary battery 10. Figure 2 This is a top view of the non-aqueous electrolyte secondary battery 10. Figure 3 In the electrode body 13 that constitutes the non-aqueous electrolyte secondary battery 10, equivalent to Figure 1 A cross-sectional view of section AA is shown. Hereinafter, the non-aqueous electrolyte secondary battery 10 will be referred to as battery 10. Battery 10 includes: a square outer casing 11 with an opening at the top, and a sealing plate 12 that seals the opening. The outer casing 11 has a bottom that is generally rectangular in shape when viewed from above, and sidewalls that are erected around the periphery of the bottom. The sidewalls are formed approximately perpendicular to the bottom. The battery casing 100 is composed of the outer casing 11 and the sealing plate 12. Both the outer casing 11 and the sealing plate 12 are made of metal, preferably aluminum or an aluminum alloy.

[0025] The battery 10 has a flattened, wound electrode body 13 and a non-aqueous electrolyte. For example... Figure 3 As shown, the electrode body 13 is formed as follows: the first separator 30, the positive electrode plate 14, the second separator 31 and the negative electrode plate 15 are overlapped in such a way that the first separator 30 or the second separator 31 is sandwiched between the positive electrode plate 14 and the negative electrode plate 15, and are wound more than 10 times. Figure 3 In this diagram, to facilitate understanding of the relationships between the constituent elements of the electrode body 13, the number of turns is drastically reduced compared to the actual configuration. The thick black line represents the positive electrode plate 14, the line with diagonal lines inside represents the negative electrode plate 15, and the dashed lines represent the first separator 30 and the second separator 31. Only the outer peripheral winding end of the second separator 31 is shown. The electrode body 13 and the non-aqueous electrolyte are housed within the battery casing 100. In the electrode body 13, the width direction of the electrode plates (positive electrode plate 14, negative electrode plate 15) is the spool direction, which is along... Figure 1 In the left and right directions. Furthermore, the electrode body 13 is wound more than 10 times, for example, 30 to 40 times.

[0026] Non-aqueous electrolytes comprise a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. The non-aqueous solvent can be, for example, esters, ethers, nitriles, amides, and mixtures of two or more of these. The non-aqueous solvent may also contain halogen-substituted derivatives obtained by substituting at least a portion of the hydrogen atoms of these solvents with halogen atoms such as fluorine. The electrolyte salt can be, for example, a lithium salt such as LiPF6.

[0027] The positive electrode plate 14 is an elongated strip having a metallic positive electrode core and positive electrode binder layers formed on both sides of the positive electrode core. One end of the positive electrode core in its unfolded state is exposed along its length, thus forming a strip-shaped exposed portion 14a of the positive electrode core. Here, the positive electrode density of the positive electrode plate 14 is 2.600 g / cm³. 3 Above and 3.000 g / cm 3 Similarly, the negative electrode plate 15 is a strip having a metal negative electrode core and negative electrode binder layers formed on both sides of the negative electrode core, and has a strip-shaped negative electrode core exposure portion 15a formed where the other end of the negative electrode core in the width direction is exposed along the length direction when the negative electrode core is in the unfolded state. The electrode body 13 has: one end side in the winding axis direction ( Figure 1 On the right side) is a positive electrode core exposed portion 14a, and on the other end side in the winding axis direction ( Figure 1 The negative electrode core 15a is exposed on the left side, and the positive electrode plate 14 and the negative electrode plate 15 are wound into a flat structure. Thus, as with Figure 3 As shown in the cross-section of a plane orthogonal to the axial direction, the electrode body 13 has: a flat portion 13b with a flat outer peripheral surface, and a first direction in the flat portion 13b ( Figure 3The two curved surfaces 13a are located at both ends in the left and right directions, with curved outer peripheral surfaces. Each curved surface 13a is curved in a way that the inner peripheral side is concave. For example, each curved surface 13a can be a curved surface with an outer peripheral surface that is an arc-shaped cross section.

[0028] like Figure 1 As shown, a positive current collector 16 is connected to the stacked portion of the exposed positive electrode core 14a, and a negative current collector 18 is connected to the stacked portion of the exposed negative electrode core 15a. Ideally, the positive current collector 16 is made of aluminum or an aluminum alloy. Ideally, the negative current collector 18 is made of copper or a copper alloy. The positive terminal 17 has a flange portion 17a disposed on the outer side of the sealing plate 12. Figure 2 The negative terminal 19 has a flange portion 19a disposed on the outer side of the battery of the sealing plate 12, and an embedded portion embedded in the through hole provided in the sealing plate 12, and electrically connected to the positive current collector 16. Figure 2 ), and embedded in the through hole provided in the sealing plate 12, and electrically connected to the negative current collector 18.

[0029] The positive terminal 17 and the positive current collector 16 are fixed to the sealing plate 12 by means of an inner insulating member 20 and an outer insulating member 21, respectively. The inner insulating member 20 is disposed between the sealing plate 12 and the positive current collector 16, and the outer insulating member 21 is disposed between the sealing plate 12 and the positive terminal 17. Similarly, the negative terminal 19 and the negative current collector 18 are fixed to the sealing plate 12 by means of an inner insulating member 22 and an outer insulating member 23, respectively. The inner insulating member 22 is disposed between the sealing plate 12 and the negative current collector 18, and the outer insulating member 23 is disposed between the sealing plate 12 and the negative terminal 19.

[0030] The electrode body 13 is housed within the outer casing 11. The sealing plate 12 is welded to the opening edge of the outer casing 11 by laser welding or the like. The sealing plate 12 has an electrolyte injection hole 26, which is sealed by a sealing plug 27 after a non-aqueous electrolyte is injected into the battery casing 100.

[0031] Furthermore, such as Figure 3As shown, the electrode body 13 includes: a winding end tape 33 fixed at its outermost periphery and a positive electrode protective tape 35 adhered to the winding start end on the inner periphery side of the positive electrode plate 14. The winding end tape 33 is attached to the outermost peripheral surface of the electrode body 13 in a manner that fixes the winding end of the electrode body 13 to the outermost peripheral surface of the electrode body 13. In this example, a first separator 30 is disposed on the outermost peripheral surface of the electrode body 13. The winding end tape 33 is attached to the outermost peripheral surface of the first separator 30 located at the outermost periphery of the electrode body 13 in a manner that the winding end of the first separator 30 is located across the winding direction. This prevents the electrode body 13 from unwinding. The material of the winding end tape 33 is not particularly limited, and a resin film with an adhesive layer formed on one side of a substrate layer such as polypropylene can be used. As the substrate layer, polyimide, polyethylene terephthalate, etc., can also be used.

[0032] The positive electrode protection strip 35 can prevent damage to the ends of the positive electrode plate 14, or the separators 30, 31, or the negative electrode plate 15, and prevent the positive electrode binder layer from being peeled off from the positive electrode core. Figure 4 This diagram illustrates the starting end of the winding of the positive electrode plate 14 and the positive electrode protective strip 35 within the electrode body 13. (See diagram below.) Figure 3 As shown, two positive electrode protection strips 35 face each other, with the adhesive layer on their inner surfaces attached to the side of the end of the positive electrode plate 14, and the portions overflowing from the end of the positive electrode plate 14 overlap and adhere to each other. Thus, the starting end of the winding of the positive electrode plate 14 is covered by the two positive electrode protection strips 35. The material of the positive electrode protection strips 35 is not particularly limited; for example, a resin film with an adhesive layer formed on one side of a substrate such as polypropylene can be used. As the substrate layer, polyimide, polyethylene terephthalate, etc., can also be used.

[0033] In this example, the winding end strip 33 is disposed in one of the two curved surfaces 13a on the outer peripheral surface of the electrode body 13. Figure 3 (Right side) Curved face 13a. Figure 3 In the electrode body 13, a curved surface 13a is disposed on the upper side, or it may be disposed on the lower side. Furthermore, the positive electrode protection strip 35 is disposed on the side of the curved surface of the positive electrode plate 14, which is the same side as the winding end strip 33, in one of the two curved surfaces 13a of the electrode body 13. Thus, as will be described later, the formability of the electrode body 13 can be improved by having a large number of turns, thereby controlling the dimensional deviation of the electrode body 13 during manufacturing.

[0034] The following is a detailed description of the positive electrode plate 14, the negative electrode plate 15, and the separators 30 and 31 that constitute the electrode body 13.

[0035] [Positive electrode plate]

[0036] As described above, the positive electrode plate 14 has a positive electrode core and positive electrode binder layers formed on both sides of the positive electrode core. The positive electrode core can be a foil of a metal that is stable within the potential range of the positive electrode, such as aluminum or an aluminum alloy, or a thin film with the metal disposed on its surface. The positive electrode binder layers include a positive electrode active material, a conductive material, and a binder. The positive electrode plate 14 is manufactured by coating a positive electrode binder slurry containing a positive electrode active material, a conductive material, a binder, and a dispersion medium onto the positive electrode core, drying the coating to remove the dispersion medium, and then compressing it to form the positive electrode binder layers on both sides of the positive electrode core.

[0037] Examples of lithium transition metal oxides containing transition metal elements such as Co, Mn, and Ni can be used as positive electrode active materials. For example, Li0.05 transition metal oxides are Li0.05. x CoO2, Li x NiO2, Li x MnO2, Li x Co y Ni 1-y O2, Li x Co y M 1-y O z Li x Ni 1- y M y O z Li x Mn2O4, Li x Mn 2-y M y O4, LiMPO4, Li2MPO4F (M; at least one of Na, Mg, Sc, Y, Mn, Fe, Co, Ni, Cu, Zn, Al, Cr, Pb, Sb, B, 0 < x ≤ 1.2, 0 < y ≤ 0.9, 2.0 ≤ z ≤ 2.3). These can be used individually or in combination. From the perspective of achieving high capacity in battery 10, the positive electrode active material preferably contains Li. x NiO2, Li x Co y Ni 1-y O2, Li x Ni 1-y M y O z (M: at least one of Na, Mg, Sc, Y, Mn, Fe, Co, Ni, Cu, Zn, Al, Cr, Pb, Sb, B, 0 < x ≤ 1.2, 0 < y ≤ 0.9, 2.0 ≤ z ≤ 2.3) and other lithium nickel composite oxides.

[0038] Examples of conductive materials used in the positive electrode flux layer include carbon black (CB), acetylene black (AB), Ketjen black, carbon nanotubes (CNTs), and carbon-based particles such as graphite. These can be used alone or in combination of two or more. Carbon black is preferred as the conductive material used in the positive electrode flux layer.

[0039] Examples of binders used in the positive electrode binder layer include fluorinated resins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyimide resins, acrylic resins, and polyolefin resins. These can be used alone or in combination of two or more. Polyvinylidene fluoride is preferably used as a binder in the positive electrode binder layer.

[0040] The positive electrode density of positive electrode plate 14 is 2.600 g / cm³. 3 Above and 3.000 g / cm 3 The preferred value is 2.753 g / cm³. 3 Above and 2.902 g / cm 3 Below. Furthermore, the length along the longitudinal direction of the coil of the positive electrode plate 14 is 4895 mm or more. In this example, even with such a high positive electrode density configuration, the formability of the electrode body 13 can be improved by increasing the number of turns of the electrode body 13.

[0041] [Negative electrode plate]

[0042] The negative electrode plate 15 has a negative electrode core and a negative electrode binder layer formed on both sides of the negative electrode core. The negative electrode binder layer contains a negative electrode active material and a binder.

[0043] The negative electrode core can be made of a foil of a metal that is stable within the potential range of the negative electrode, such as copper or copper alloy, or a thin film with the metal on its surface. The negative electrode plate 15 is manufactured by coating the negative electrode core with a negative electrode mixture slurry containing a negative electrode active material, a binder, and a dispersion medium, drying the coating to remove the dispersion medium, and then compressing it to form a negative electrode mixture layer on both sides of the negative electrode core.

[0044] In the negative electrode composite layer, the negative electrode active material is not particularly limited, as long as it can reversibly absorb, store, and release lithium ions. It can be carbon materials such as natural graphite and artificial graphite, metals alloyed with lithium such as silicon (Si) and tin (Sn), alloys containing metal elements such as Si and Sn, composite oxides, etc. Carbon materials are preferred as the negative electrode active material, and natural graphite is even more preferred. The negative electrode active material can be used alone or in combination of two or more.

[0045] The negative electrode density of negative electrode plate 15 is 1.52 g / cm³. 3That's all. Additionally, the length along the winding direction of the negative electrode plate 15 is 5115 mm or more.

[0046] [Separator]

[0047] Each separator 30 and 31 can be a porous sheet with ion permeability and insulation. Specific examples of porous sheets include microporous films, woven fabrics, and nonwoven fabrics. Ideal materials for separators 30 and 31 include polyethylene, polypropylene, and other olefin resins, as well as cellulose. Separators 30 and 31 can also be laminates having a cellulose fiber layer and a thermoplastic resin fiber layer such as an olefin resin. Furthermore, separators 30 and 31 can be multilayer separators containing a polyethylene layer and a polypropylene layer, or they can be coated with materials such as aramid resins or ceramics. For example, separators 30 and 31 can also be made into three-layer separators: a polyethylene layer, a polypropylene layer, and a polyethylene layer.

[0048] [Positions of the starting points of the winding for the positive and negative electrodes]

[0049] In addition, the inner circumferential side of the negative electrode plate 15 is located 1.0 layer on the inner circumferential side of the inner circumferential side of the positive electrode plate 14. Figure 5 Assume Figure 3 A diagram showing the positional relationship between the ends of the positive electrode 14 and the negative electrode 15 when the starting end of the winding of the negative electrode 15 is located 0.5 layers inside the starting end of the winding of the positive electrode 15 is shown. Figure 5 In the example shown, it is located at Figure 3 Arrow A indicates the winding start end of the negative electrode plate 15. Figure 5 In this context, it is assumed that the negative electrode plate 15 is in a straight line within the area indicated by arrow A. At this point, the area indicated by arrow A represents layer 1.0. Figure 3 In this example, the starting end of the winding of the negative electrode plate 15 is located 1.0 layer on the inner circumference of the starting end of the winding of the positive electrode plate 14. Therefore, as described above, the positive electrode protection strip 35 is arranged along the side of the curved surface that serves as the starting end of the winding of the positive electrode plate 14 in one curved portion 13a of the electrode body 13. Thus, when the starting end of the winding of the positive electrode plate 14 is located in or near one curved portion 13a, the starting end of the winding of the negative electrode plate 15 can be located in or near another curved portion 13a. Therefore, in the length direction of the flat portion 13b ( Figure 3 The negative electrode plate 15 is not disposed near the center of the part in the left-right direction. Therefore, when the electrode body 13 is formed by pressing the electrode body 13 in one direction after it is wound in a cylindrical manner with a pressing machine, the flat part 13b is easily formed, thus improving the formability of the electrode body 13.

[0050] [Battery manufacturing method]

[0051] Figure 6 This is a flowchart illustrating a battery manufacturing method according to an example of an embodiment. The battery manufacturing method includes a pre-pressing electrode forming step and a subsequent forming and pressing step. Specifically, firstly, Figure 6 In step S1, the first separator 30, the positive electrode plate 14, the second separator 31, and the negative electrode plate 15 are overlapped and wound at least 10 turns, for example, 30 to 40 turns, in such a way that the first separator 30 or the second separator 31 is sandwiched between the positive electrode plate 14 and the negative electrode plate 15, and then wound to form a cylindrical pressing pre-electrode body on its outer peripheral surface. Then, in step S2, the pressing pre-electrode body is formed in a direction orthogonal to the first direction. Figure 3 The electrode body is flattened in the vertical direction by applying pressure to it at room temperature using a pressing machine to form the shape. Figure 3 The forming and pressing process of the flat electrode body 13 shown.

[0052] It should be noted that, Figure 3 In the configuration, the positive electrode protective strips 35 adhered to the starting ends of the two positive electrode plates 14 overlap, but are not limited to this. Figure 7 Another example of a positive electrode protective tape 35a is shown, which is adhered to the starting end of the winding of the positive electrode plate 14. Figure 7 In another example, the positive electrode protection tape 35a is folded in half at the middle to form a U-shaped cross section by attaching the two end portions of a positive electrode protection tape 35a to the two sides of the starting end of the winding of the positive electrode plate 14, and the starting end of the winding of the positive electrode plate 14 is covered by the positive electrode protection tape 35a.

[0053] By employing the battery 10 and its manufacturing method described above, the formability of the electrode body 13 can be improved by having up to 10 or more turns, thereby suppressing dimensional deviations of the electrode body 13 during manufacturing. Specifically, the winding end strip 33 attached to the outermost peripheral surface of the electrode body 13 is disposed on a curved portion 13a of the electrode body 13. Therefore, the flat portion 13b facing the flattening direction of the electrode body 13 is not provided with the winding end strip 33, making it easier to uniformly flatten the electrode body 13 and efficiently apply pressure in the thickness direction of the electrode body 13, thus facilitating the formation of the flat portion 13b. Furthermore, a positive electrode protection strip 35 is adhered to the winding start side end of the positive electrode plate 14, allowing this winding start side end to easily slide between other components such as the separators 30 and 31, thereby improving the responsiveness of the electrode body 13 to pressing. Thus, it becomes easier to form a flat electrode body 13 from a pre-pressing electrode body with a cylindrical outer peripheral surface. Furthermore, the positive electrode protection strip 35 is arranged along the curved surface of the positive electrode plate 14 at the starting end of the winding of a curved section 13a, thereby making it easier to uniformly flatten the electrode body 13 and thus making it easier to form the flat portion 13b. Therefore, the formability of the electrode body 13 can be improved by having a large number of turns, thereby suppressing dimensional deviations such as thickness of the electrode body 13 during manufacturing.

[0054] Furthermore, by positioning the inner circumferential starting end of the negative electrode plate 15 at the inner circumferential 1.0 layer of the inner circumferential starting end of the positive electrode plate 14, as described above, it becomes easier to form the flat portion 13b, thereby further improving the formability of the electrode body 13. Additionally, this configuration improves the cushioning properties of the inner circumferential portion of the electrode body 13. This further enhances the formability of the electrode body 13, enabling the production of electrode bodies 13 with minimal dimensional deviations under low pressure.

[0055] Hereinafter, the electrode body 13 of the battery 10 of this disclosure will be further described through examples, and the electrode bodies of the batteries of Comparative Examples 1 to 4 will also be described.

[0056] <Example>

[0057] [Making the positive electrode plate]

[0058] As the positive electrode active material, LiNi was mixed with it in a solid component mass ratio of 96:3:1. 0.35 Co 0.35 Mn 0.30A positive electrode slurry is prepared by mixing lithium metal composite oxide (O2), carbon black as a conductive material, and polyvinylidene fluoride (PVdF) as a binder, with an appropriate amount of N-methyl-2-pyrrolidone (NMP) added. This positive electrode slurry is coated onto both sides of a positive electrode core formed from aluminum foil with a thickness of 15 μm. After the coating dries, it is compressed using a compression roller and cut into specified electrode sizes to form a positive electrode plate 14 with positive electrode slurry layers formed on both sides of the positive electrode core. The thickness of the positive electrode slurry layer after compression is set to 76 μm on one side. The length of the positive electrode plate 14 in the width direction is set to 131.8 mm. The width (length in the width direction) of the exposed portion 14a of the positive electrode core at one end of the positive electrode plate 14 in the width direction is set to 15.2 mm. The length in the length direction along the roll direction of the positive electrode plate 14 is set to 4950 mm. Therefore, the positive electrode density of the positive electrode plate 14 is set to 2.800 g / cm³. 3 .

[0059] [Making the negative electrode plate]

[0060] A dispersion of graphite powder (as the negative electrode active material), sodium salt of carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR) (as a binder) was prepared using water as the dispersion medium, with a solid component mass ratio of 98:1:1. This negative electrode slurry was coated onto both sides of a negative electrode core formed from a 10 μm thick copper foil. After drying, the coating was compressed using a compression roller and cut into specified electrode sizes to fabricate a negative electrode plate 15 with negative electrode slurry layers formed on both sides of the negative electrode core. The thickness of the negative electrode slurry layer, after compression, was set to 67 μm on one side. The length of the negative electrode plate 15 in the width direction was set to 133.8 mm. The width (length in the width direction) of the exposed portion 15a of the negative electrode core at the other end of the negative electrode plate 15 in the width direction was set to 10.0 mm. The length in the length direction along the roll direction of the negative electrode plate 15 was set to 5150 mm.

[0061] [Making the separator]

[0062] The first separator 30 and the second separator 31 are three-layer separators consisting of a polyethylene layer, a polypropylene layer, and a polyethylene layer, respectively. The thickness of each separator 30 and 31 is set to 14 μm, and the length (width) in the width direction is set to 127 mm.

[0063] [Electrode fabrication]

[0064] To sandwich the first separator 30 or the second separator 31 between the positive electrode plate 14 and the negative electrode plate 15, the first separator 30, the positive electrode plate 14, the second separator 31, and the negative electrode plate 15 are overlapped and wound into a cylindrical shape for more than 10 turns. Then, the electrode body 13 is flattened radially by pressing. At this time, the exposed core portions of the positive electrode plate 14 and the negative electrode plate 15 are displaced so that they do not overlap with the active material layers of the opposing electrode plates. The exposed core portion of the positive electrode plate 14 is positioned at one end of the electrode body 13 in the axial direction, and the exposed core portion of the negative electrode plate 15 is positioned at the other end in the axial direction. Furthermore, a winding end tape 33 is attached to the outermost circumferential surface of the electrode body 13 to fix the winding end of the electrode body 13 to the outermost circumferential surface of the electrode body 13. The winding end strip 33 is disposed on a curved surface 13a of the electrode body 13. Additionally, a positive electrode protective strip 35 is adhered to the winding start end of the inner circumference side of the positive electrode plate 14. This positive electrode protective strip 35 is disposed along the curved surface of the winding start end of the positive electrode plate 14 within a curved surface 13a of the electrode body 13. Furthermore, the winding start end of the inner circumference side of the negative electrode plate 15 is positioned 1.0 layer inside the winding start end of the positive electrode plate 14.

[0065] <Comparative Example 1>

[0066] Figure 8 In the electrode body 40 constituting the battery of Comparative Example 1, corresponding to Figure 3 The image. (As shown) Figure 8 As shown, in the electrode body 40 of Comparative Example 1, the winding end tape 33 attached to the outermost peripheral surface of the electrode body 40 is disposed on the outer surface of the flat portion 13b of the electrode body 40. Furthermore, a positive electrode protective tape 35 is adhered to the winding start side end of the positive electrode plate 14, and this positive electrode protective tape 35 is disposed on the inner peripheral side portion of the flat portion 13b of the electrode body 40. Furthermore, the winding start side end of the inner peripheral side of the negative electrode plate 15 is located 0.5 layers inside the inner peripheral side of the winding start side end of the positive electrode plate 14. The electrode body 40 of Comparative Example 1 is manufactured with the same other configurations as in the embodiment.

[0067] <Comparative Example 2>

[0068] Figure 9 In the electrode body 40a constituting the battery of Comparative Example 2, corresponding to Figure 3 The image. (As shown) Figure 9 As shown, in the electrode body 40a of Comparative Example 2, a positive electrode protective strip 35 is adhered to the winding start side end of the positive electrode plate 14, and this positive electrode protective strip 35 is disposed on the inner peripheral side of the flat portion 13b of the electrode body 40a. Furthermore, the winding start side end of the inner peripheral side of the negative electrode plate 15 is located 0.5 layers on the inner peripheral side of the winding start side end of the positive electrode plate 14. The electrode body 40a of Comparative Example 2 is manufactured with the same other configurations as in the embodiment.

[0069] <Comparative Example 3>

[0070] Figure 10 In the electrode body 40b constituting the battery of Comparative Example 3, corresponding to Figure 3 The image. (As shown) Figure 10 As shown, in the electrode body 40b of Comparative Example 3, a positive electrode protective strip 35 is adhered to the winding start side end of the positive electrode plate 14, and this positive electrode protective strip 35 is disposed on the inner peripheral side of the flat portion 13b of the electrode body 40b. Furthermore, the winding start side end of the inner peripheral side of the negative electrode plate 15 is located 0.8 layers on the inner peripheral side of the winding start side end of the positive electrode plate 14. The electrode body 40b of Comparative Example 3 is manufactured with the same other configurations as in the embodiment.

[0071] <Comparative Example 4>

[0072] Figure 11 In the electrode body 40c constituting the battery of Comparative Example 4, corresponding to Figure 3 The image. (As shown) Figure 11 As shown, in the electrode body 40c of Comparative Example 4, a positive electrode protective strip 35 is adhered to the winding start side end of the positive electrode plate 14, and this positive electrode protective strip 35 is disposed on the inner peripheral side of the flat portion 13b of the electrode body 40c. Furthermore, the winding start side end of the inner peripheral side of the negative electrode plate 15 is located 1.2 layers inside the inner peripheral side of the winding start side end of the positive electrode plate 14. The electrode body 40c of Comparative Example 4 is manufactured with the same other configurations as in the embodiment.

[0073] [Evaluation Method]

[0074] Using the five electrode bodies 13, 40, 40a-40c of the above-described Examples and Comparative Examples 1-4, the thickness deviation σ of the electrode bodies 13, 40, 40a-40c was measured, and the deviation σ was evaluated by comparison. Specifically, using a pressing machine, the electrode bodies 13, 40, 40a-40c of Examples and Comparative Examples 1-4, whose outer peripheral surfaces were cylindrical before pressing, were flattened radially to form flat electrode bodies 13, 40, 40a-40c under a specified pressing pressure and for a specified time. The formed electrode bodies 13, 40, 40a-40c were clamped with a jig and subjected to a load of 10gf. The thickness of the electrode bodies 13, 40, 40a-40c in the flattening direction was measured using a laser displacement meter. Ten electrodes of each of the five types were formed consecutively, and the thicknesses of the electrodes 13, 40, 40a to 40c were measured and recorded. The thickness deviation (standard deviation) σ of each of the five types was confirmed.

[0075] [Evaluation Results]

[0076] Table 1 shows the thickness deviation σ of electrode bodies 13, 40, 40a-40c of Examples 1-4, positive electrode density, position of winding end strip 33 and position of positive electrode protection strip 35, presence or absence of positive electrode protection strip 35, and the length of the remaining negative electrode in the inner periphery, i.e., the length of the extension of the winding start end of the positive electrode plate 14 and the winding start end of the negative electrode plate 15 on the inner periphery side.

[0077] [Table 1]

[0078]

[0079] In Table 1, “R part” means one or another curved part 13a of electrode body 13, 40, 40a to 40c, and “flat part” means the flat part 13b of electrode body 13, 40, 40a to 40c.

[0080] According to the evaluation results shown in Table 1, in the case of the embodiment, the thickness deviation of the electrode body 13 is significantly reduced compared to the thickness deviation of the electrode bodies 40, 40a to 40c in each of the Comparative Examples 1 to 4. The reason for this is that in the embodiment, the winding end strip 33 and the positive electrode protection strip 35 are disposed on a curved surface 13a of the electrode body 13, so that the winding start end of the inner circumference side of the negative electrode plate 15 is located 1.0 layer on the inner circumference side of the winding start end of the positive electrode plate 14, thereby improving the formability.

[0081] It should be noted that the above embodiments and examples describe the case where the winding end strip 33 and the positive electrode protection strip 35 are disposed on the same side of the curved surface 13a of the electrode body 13. However, this disclosure is not limited to this. The winding end strip 33 and the positive electrode protection strip 35 may also be disposed on two different curved surfaces 13a of the electrode body 13. For example, the winding end strip 33 may be disposed on one curved surface 13a of the two curved surfaces 13a, and the positive electrode protection strip 35 may be disposed on the other curved surface 13a along the curved surface of the end of the winding start side of the positive electrode plate 14.

[0082] Explanation of reference numerals in the attached figures

[0083] 10. Non-aqueous electrolyte secondary batteries (cells)

[0084] 11. Outer shell

[0085] 12 Sealing Board

[0086] 13 Electrode bodies

[0087] 13a Curved face

[0088] 13b Flat section

[0089] 14 Positive electrode plate

[0090] 14a Exposed portion of positive electrode core

[0091] 15 Negative electrode plate

[0092] 15a Exposed part of negative electrode core

[0093] 16 Positive current collector

[0094] 17 Positive extremes

[0095] 18 Negative current collector

[0096] 19 Negative extremes

[0097] Inner insulating components 20 and 22

[0098] 21, 23 External insulating components

[0099] 24 Insulating sheets

[0100] 26 Electrolyte injection hole

[0101] 27 sealing plug

[0102] 30 First separator

[0103] 31 Second separator

[0104] 33. End of winding tape

[0105] 35, 35a Positive electrode protection band

[0106] Electrode bodies 40, 40a~40c

[0107] 100 Battery casing.

Claims

1. A non-aqueous electrolyte secondary battery, comprising: An electrode body is formed by overlapping the first separator, the positive electrode plate, the second separator, and the negative electrode plate in such a way that the first separator or the second separator is sandwiched between the positive electrode plate and the negative electrode plate, and by winding them together for more than 10 turns. The electrode body has a flat portion with a flat outer peripheral surface and two curved portions with curved outer peripheral surfaces disposed at both ends of the flat portion in a first direction. The non-aqueous electrolyte secondary battery has the following features: The winding end tape is attached to the outermost circumferential surface of the electrode body in a manner that fixes the winding end of the electrode body to the outermost circumferential surface of the electrode body; and The positive electrode protective tape adhered to the inner circumferential side of the positive electrode plate at the starting end of the winding process. The winding end strip is disposed on one of the two curved surfaces. The positive electrode protection strip is disposed on one or the other of the two curved surfaces, along the curved surface of the end of the positive electrode plate at the beginning of the winding. The starting end of the positive electrode plate is located on one or the other of the two curved surfaces. The inner circumferential side of the negative electrode plate is positioned 1.0 layer from the inner circumferential side of the inner circumferential side of the positive electrode plate.

2. The non-aqueous electrolyte secondary battery according to claim 1, wherein, The positive electrode density of the positive electrode plate is 2.600 g / cm³. 3 Above and 3.000 g / cm 3 the following.

3. The non-aqueous electrolyte secondary battery according to claim 2, wherein, The density of the positive electrode is 2.753 g / cm³. 3 Above and 2.902 g / cm 3 the following.

4. In the non-aqueous electrolyte secondary battery according to any one of claims 1 to 3, wherein, The negative electrode density of the negative electrode plate is 1.52 g / cm³. 3 The positive electrode plate has a length of 4895 mm or more along the winding direction, and the negative electrode plate has a length of 5115 mm or more along the winding direction.

5. A method for manufacturing a non-aqueous electrolyte secondary battery, comprising the method for manufacturing a non-aqueous electrolyte secondary battery according to any one of claims 1 to 4, and comprising: The first separator, the positive electrode, the second separator, and the negative electrode are overlapped and wound more than 10 turns in such a manner that at least the first separator or the second separator is sandwiched between the positive electrode plate and the negative electrode plate, thereby forming a pre-pressing electrode body forming process; and After the electrode body forming process before pressing, the electrode body before pressing is pressed in a direction orthogonal to the first direction to form a flat electrode body forming pressing process.

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