Method for manufacturing positive electrode plate for nonaqueous electrolyte secondary battery and method for manufacturing nonaqueous electrolyte secondary battery

Abstract

A positive electrode plate for a nonaqueous electrolyte secondary battery has a protective layer formed in a region adjacent to a positive electrode active material layer at a core body exposed portion. A manufacturing method for the positive electrode plate includes a coating and drying step in which a positive electrode active material layer and the protective layer are coated on a positive electrode core body, and after coating in which a protruding portion is formed between a portion of the protective layer that enters an inner side in a width direction as compared to a side end of the core body exposed portion and a center in the width direction, the positive electrode active material layer and the protective layer are dried, and a compression step in which the positive electrode active material layer and the protective layer are compressed in a manner that presses the protruding portion formed by the coating and drying step and the positive electrode active material layer.

Description

Technical Field

[0001] This disclosure relates to a method for manufacturing a positive electrode plate for a non-aqueous electrolyte secondary battery and a method for manufacturing a non-aqueous electrolyte secondary battery. Background Technology

[0002] In recent years, non-aqueous electrolyte secondary batteries, represented by lithium-ion batteries, have been widely used as rechargeable batteries to achieve high output and high energy density. Non-aqueous electrolyte secondary batteries have an electrode body consisting of positive and negative electrode plates stacked together with separators.

[0003] Patent Document 1 describes the following: The positive electrode plate of a non-aqueous electrolyte secondary battery includes a metal foil, an active material layer formed on the surface of the metal foil, and an insulating layer. The portion of the metal foil along its edge is designated as a non-active material forming portion, and the insulating layer is formed on this non-active material forming portion. The thickness of the insulating layer gradually decreases from its position adjacent to the active material layer towards the core exposure portion. Furthermore, the core exposure portion of the insulating layer has a cross-sectional arc shape that gradually approaches the surface of the core exposure portion.

[0004] Patent Document 2 describes the following: For the positive electrode plate of a secondary battery, after the coating and drying processes of the insulator and before the stamping process of the insulator, the insulator coated on the core is made to have the same thickness as or thicker than the dried positive electrode compound layer. Then, the positive electrode compound layer and the insulator are heated and stamped by a stamping process. At this time, the thickness of the insulator gradually decreases towards the exposed end of the core.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2017-188371

[0008] Patent Document 2: Japanese Patent No. 6336821 Summary of the Invention

[0009] In positive electrode plates for secondary batteries, a protective layer is formed on at least one side of the positive electrode core in a region adjacent to the positive electrode active material layer. This protective layer is, for example, a porous layer. On the other hand, to achieve high capacity and high output in secondary batteries, a high filling density of the positive electrode active material layer is required. With this high filling density, the portion of the positive electrode core with the positive electrode active material layer is pressed and elongated along the plate thickness direction. At this time, the exposed portion of the positive electrode core without the positive electrode active material layer is not pressed along the plate thickness direction, and therefore elongates less. Consequently, a difference in elongation occurs between the portion with the positive electrode active material layer and the exposed portion of the positive electrode core. Therefore, the following problems may arise: wrinkles may occur in the exposed portion of the positive electrode core during the compression of the positive electrode active material layer; or, in the case of stacking positive electrode plates, negative electrode plates, and separators to form a wound electrode body, winding misalignment of the positive electrode plate may occur during the winding process of the electrode body.

[0010] The present disclosure discloses a method for manufacturing a positive electrode plate for a non-aqueous electrolyte secondary battery, comprising a main body having a positive electrode active material layer formed on a positive electrode core, and a core exposed portion where the positive electrode core is exposed without a positive electrode active material layer. The method further comprises: a coating and drying step in which a positive electrode active material layer and a protective layer are coated onto the positive electrode core; after coating the protective layer to form a raised portion between the portion of the protective layer extending into the inner width direction relative to the side end of the core exposed portion and the center in the width direction, the positive electrode active material layer and the protective layer are dried; and a compression step in which the protective layer and the positive electrode active material layer are compressed by pressing the raised portion formed in the coating and drying step.

[0011] The present disclosure provides a method for manufacturing a non-aqueous electrolyte secondary battery, comprising: an electrode body fabrication step, wherein an electrode body is fabricated including a positive electrode plate, a negative electrode plate, and a separator for a non-aqueous electrolyte secondary battery, which are manufactured using the present disclosure's method for manufacturing a positive electrode plate for a non-aqueous electrolyte secondary battery; and an assembly step, wherein the electrode body and a non-aqueous electrolyte are arranged within a housing.

[0012] According to one aspect of the present disclosure, the manufacturing method of the positive electrode plate for a non-aqueous electrolyte secondary battery and the manufacturing method of a non-aqueous electrolyte secondary battery can prevent the formation of wrinkles in the positive electrode plate and can prevent the winding misalignment of the positive electrode plate in the case of forming a wound electrode body. Attached Figure Description

[0013] Figure 1This is a cross-sectional view of a non-aqueous electrolyte secondary battery as an example of an implementation method.

[0014] Figure 2 It is the composition Figure 1 A perspective view illustrating a wound electrode body of a non-aqueous electrolyte secondary battery, with the wound end unwound.

[0015] Figure 3 This is a flowchart illustrating a method for manufacturing a non-aqueous electrolyte secondary battery, representing one embodiment.

[0016] Figure 4 This is a flowchart illustrating an example of a method for manufacturing a positive electrode plate for a non-aqueous electrolyte secondary battery.

[0017] Figure 5 It is the formation of composition Figure 2 A partial unfolded view of the positive electrode plate in the length direction of a non-aqueous electrolyte secondary battery before it is cut off.

[0018] Figure 6 yes Figure 5 AA sectional view.

[0019] Figure 7 (a) represents the state of the positive electrode plate after coating and drying, and before the compression process, in one example of the implementation method. Figure 6 The enlarged image of the upper half is quite similar to the image. Figure 7 (b) represents the state of the positive electrode plate after coating and drying, and after the compression process, in one example of the implementation method. Figure 6 The enlarged image of the upper half is quite similar to the image.

[0020] Figure 8 This is a simplified diagram of a press used in the compression process in one embodiment.

[0021] Figure 9 It constitutes Figure 8 The front view of the rollers of the stamping press.

[0022] Figure 10 (a) represents the state of the positive electrode plate before coating and drying, and before the compression process, in the manufacturing method of Comparative Example 1. Figure 6 The image corresponding to the enlarged upper part. Figure 10 (b) represents the state of the positive electrode plate after coating and drying, and after the compression process, in the manufacturing method of Comparative Example 1. Figure 6 The image corresponding to the enlarged upper part.

[0023] Figure 11 (a) represents the state of the positive electrode plate before coating and drying, and before the compression process, in the manufacturing method of Comparative Example 2. Figure 6 The image corresponding to the enlarged upper part. Figure 11 (b) represents the state of the positive electrode plate after coating and drying, and after the compression process, in the manufacturing method of Comparative Example 2. Figure 6 The image corresponding to the enlarged upper part.

[0024] Figure 12 (a) represents the state of the positive electrode plate before the coating and drying process and before the compression process in the manufacturing method of Comparative Example 3. Figure 6 The image corresponding to the enlarged upper part. Figure 12 (b) represents the state of the positive electrode plate after coating and drying, and after the compression process, in the manufacturing method of Comparative Example 3. Figure 6 The image corresponding to the enlarged upper part.

[0025] Figure 13A This is a schematic diagram showing the state of a positive electrode plate manufactured by the manufacturing method described in the embodiment after the cutting process.

[0026] Figure 13B This is a schematic diagram showing the state of the positive electrode plate manufactured by the manufacturing method of Comparative Example 1 after the cutting process. Detailed Implementation

[0027] To solve the aforementioned problems, the inventors conducted in-depth research and discovered a method for manufacturing a positive electrode plate for a non-aqueous electrolyte secondary battery. The method comprises a main body having a positive electrode active material layer formed on a positive electrode core, and a core exposed portion where a positive electrode active material layer is not formed on the positive electrode core. The positive electrode plate for the non-aqueous electrolyte secondary battery has a protective layer formed in the region adjacent to the positive electrode active material layer in the core exposed portion. The method for manufacturing the positive electrode plate for the non-aqueous electrolyte secondary battery includes a coating and drying step, in which a coating and drying process is performed on the positive electrode core... The process involves coating a positive electrode active material layer and a protective layer. After coating the portion of the protective layer that extends into the inner width direction relative to the exposed end of the core, forming a raised portion between it and the center of the width direction, the positive electrode active material layer and the protective layer are dried. A compression process follows, in which the protective layer and the positive electrode active material layer are compressed by pressing the raised portion formed during the coating and drying process. This prevents the formation of wrinkles in the positive electrode plate and prevents misalignment of the positive electrode plate in the case of forming a wound electrode body. This will be explained in detail below.

[0028] Hereinafter, an example of an embodiment of the present disclosure will be described in detail. In the following description, the specific shapes, materials, orientations, values, etc., are examples for easy understanding of the present disclosure and can be appropriately changed according to the application, purpose, specifications, etc. Hereinafter, a square battery in which a wound electrode body is housed in a square metal casing, i.e., an outer casing, will be described.

[0029] (Structure of a secondary battery)

[0030] First, use Figure 1 , Figure 2 The structure of the non-aqueous electrolyte secondary battery 10 manufactured by the manufacturing method of the embodiment will be described. Figure 1 This is a cross-sectional view of a non-aqueous electrolyte secondary battery 10. Figure 2 This is a perspective view illustrating the wound electrode body 20 constituting the non-aqueous electrolyte secondary battery 10 with the wound end unwound. Hereinafter, the non-aqueous electrolyte secondary battery 10 will be referred to as secondary battery 10.

[0031] The secondary battery 10 includes an outer casing 12 serving as the housing, and wound electrode bodies 20 disposed inside the outer casing 12. A non-aqueous electrolyte, equivalent to a non-aqueous electrolyte, is contained inside the outer casing 12. The non-aqueous electrolyte is, for example, an electrolyte containing lithium salts, and has lithium-ion conductivity.

[0032] like Figure 2 As shown, the electrode body 20 is a wound structure with the winding axis O extending along the length direction of the secondary battery 10. It is a flat structure formed by winding the positive electrode plate 22 and the negative electrode plate 26 with spacers 30 and 31 in between. In the electrode body 20, for example, the long strip-shaped positive electrode plate 22, the long strip-shaped spacer 30, the long strip-shaped negative electrode plate 26, and the long strip-shaped spacer 31 are wound in a stacked state, with the spacer 31 arranged at the outermost periphery.

[0033] like Figure 1 As shown, the metal outer casing 12 is box-shaped with an opening at the top, and the secondary battery 10 has a sealing plate 14 that closes the opening. The outer casing 12 and the sealing plate 14 can be made of aluminum or an aluminum alloy. On the sealing plate 14, from one end in the length direction ( Figure 1 The left end) protrudes with a positive terminal 15, and the other end (from the length direction) Figure 1 The negative terminal 16 protrudes from the right end of the electrode body 20. The positive terminal 15 and the negative terminal 16 are fixed and mounted to the sealing plate 14 via resin gaskets, respectively inserted into two through holes formed in the sealing plate 14. The winding axis of the electrode body 20 is parallel to the length direction of the sealing plate 14. Figure 1 The electrodes are parallel in the left and right directions. Alternatively, an insulating sheet bent in a box shape can be provided on the inner side of the outer casing 12, thereby achieving insulation between the electrode body 20 and the outer casing 12.

[0034] (Positive electrode plate)

[0035] The positive electrode plate 22 has a positive electrode core 23 and a positive electrode active material layer 24 formed on both sides of the positive electrode core 23 and containing a positive electrode active material. The positive electrode core 23 can be made of a foil of a metal that is stable in the potential range of the positive electrode, such as aluminum or an aluminum alloy, or a film on the surface of such a metal. As the positive electrode active material, a lithium transition metal oxide capable of lithium ion insertion and extraction can be used. Preferably, in addition to containing the positive electrode active material, the positive electrode active material layer 24 also contains a binder material and a conductive material. The positive electrode plate 22 has a main body portion 22a on which the positive electrode active material layer 24 is formed, and a positive electrode core exposed portion 22b where the positive electrode core 23 is exposed when the positive electrode active material layer is not formed. The positive electrode core exposed portion 22b is formed at one end in the width direction of the positive electrode plate 22 before it is wound. Furthermore, in the positive electrode plate 22, a protective layer 25 is formed along the length direction in the region adjacent to the positive electrode active material layer 24 in the exposed portion 22b of the positive electrode core. Figure 2 In the diagram, the protective layer 25 is represented by a sandy area. The protective layer 25 is, for example, a porous layer, and its thickness is less than that of the positive electrode active material layer 24. Thus, the protective layer 25 forms a venting path between itself and the separators 30 and 31 through a step formed between the exposed portion 22b of the positive electrode core and the positive electrode active material layer 24. Therefore, by allowing gas generated in the positive electrode active material layer 24 during overcharging to easily flow from the interior of the protective layer 25 to the exterior of the electrode body 20, the pressure-sensing current cut-off mechanism provided in the secondary battery 10 can be activated quickly and reliably before the internal pressure of the battery rises significantly, thereby improving safety during overcharging.

[0036] Examples of lithium transition metal oxides containing transition metal elements such as Co, Mn, and Ni can be used as positive electrode active materials. Lithium transition metal oxides, for example, are Li... 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 yO4, 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). The above lithium transition metal oxides can be used individually or in combination. Preferably, the positive electrode active material contains Li to achieve high capacity in the secondary battery 10. 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.

[0037] Examples of conductive materials used in the positive electrode active material layer 24 include carbon black (CB), acetylene black (AB), Ketjen black, carbon nanotubes (CNTs), and carbon particles such as graphite. These conductive materials can be used individually or in combination of two or more. Carbon black is preferably used as the conductive material in the positive electrode active material layer 24.

[0038] Examples of binders used in the positive electrode active material layer 24 include fluorinated resins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyimide resins, acrylic resins, and polyolefin resins. These binders can be used alone or in combination of two or more. Polyvinylidene fluoride is preferably used as the conductive material in the positive electrode active material layer 24.

[0039] Preferably, the protective layer 25 contains an inorganic oxide and a binder material. Examples of inorganic oxides used in the protective layer 25 include alumina, titanium dioxide, zirconium oxide, and silicon dioxide. Examples of binders used in the protective layer 25 include resins such as polyvinylidene fluoride (PVDF). The protective layer 25 may also contain a conductive material such as carbon. Furthermore, it is preferable that the porosity of the protective layer 25 is greater than the porosity of the positive electrode active material layer 24.

[0040] The positive electrode plate 22 can be manufactured by coating a positive electrode active material layer slurry containing a positive electrode active material, a binder and a dispersion medium and a protective layer slurry onto the positive electrode core 23, drying the coating, removing the dispersion medium, and then compressing it to form a positive electrode active material layer 24 and a protective layer 25 on both sides of the positive electrode core 23.

[0041] (Negative electrode plate)

[0042] The negative electrode plate 26 has a negative electrode core 27 and a negative electrode active material layer 28 formed on both sides of the negative electrode core 27 and containing negative electrode active material. The negative electrode core 27 can be a foil of a metal that is stable in the negative electrode potential range, such as copper or a copper alloy, or a film on the surface of such a metal. The negative electrode active material can be a carbon material or a silicon compound capable of lithium ion insertion and extraction. Preferably, the negative electrode active material layer 28 contains a binder material in addition to the negative electrode active material. The negative electrode plate 26 has a main body portion 26a on which the negative electrode active material layer 28 is formed, and a negative electrode core exposed portion 26b on which the negative electrode core 27 is exposed when the negative electrode active material layer is not formed. The negative electrode core exposed portion 26b is formed at one end in the width direction of the negative electrode plate 26 before it is wound.

[0043] There are no particular limitations on the anode active material, as long as it can reversibly absorb and release lithium ions. Examples include carbon materials such as natural graphite and artificial graphite, metals that can alloy with lithium such as silicon (Si) and tin (Sn), alloys containing metal elements such as Si and Sn, and composite oxides. Carbon materials are preferred as the anode active material, and natural graphite is more preferred. The anode active material can be used alone or in combination of two or more.

[0044] The negative electrode plate 26 can be manufactured by coating a negative electrode active material layer slurry containing negative electrode active material, binder and dispersion medium onto the negative electrode core 27, drying the coating, removing the dispersion medium, and then compressing it to form a negative electrode active material layer 28 on both sides of the negative electrode core 27.

[0045] like Figure 1 As shown, in electrode body 20, in the direction of extension of the winding axis, i.e., the winding axis direction ( Figure 1 One end on the left and right sides ( Figure 1 At the left end of the electrode body 20, a wound positive electrode core exposed portion 22b is provided. At the other end in the winding axis direction of the electrode body 20 ( Figure 1 The right end of the electrode is provided with a wound negative electrode core exposed portion 26b.

[0046] (Separator)

[0047] The separator 30 is arranged in a wound state between the positive electrode plate 22 and the negative electrode plate 26 to electrically isolate the positive electrode plate 22 and the negative electrode plate 26. The separator 31 arranged on the outermost periphery prevents short circuits between the negative electrode plate 26, which is the outermost electrode, and external components.

[0048] Each separator 30 and 31 is made of a porous sheet with ion permeability and insulation. Specific examples of porous sheets include microporous films, woven fabrics, and nonwoven fabrics. Preferred materials for separators 30 and 31 include olefin resins such as polyethylene and polypropylene, and 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, each separator 30 and 31 can be a multilayer separator including a polyethylene layer and a polypropylene layer, or a separator made by coating the surface of separators 30 and 31 with materials such as aramid resins or ceramics. For example, each separator 30 and 31 can also be a three-layer separator consisting of a polyethylene layer, a polypropylene layer, and a polyethylene layer.

[0049] In addition, in the electrode body 20, an insulating tape 60 is attached to one side of the electrode body 20 in the thickness direction in such a way that the end of the winding end side of the separator 31 disposed on the outermost periphery is fixed to the outer periphery of the electrode body 20. Figure 1 ).

[0050] Furthermore, a positive current collector 47 is electrically connected to the exposed portion 22b of the wound positive electrode core. Thus, the positive current collector 47 is electrically connected to the positive electrode plate 22. The positive current collector 47 is disposed on the opposite side of the electrode body 20 in the thickness direction. Figure 1 The positive electrode receiving member 48 (on the surface of the paper) is integrally connected with the positive electrode core exposed portion 22b. The positive electrode current collector 47 is electrically connected to the lower end of the positive electrode terminal 15, which is disposed through the first insulating member 61 on the inner side of the sealing plate 14 in the vertical direction.

[0051] A negative current collector 50 is electrically connected to the exposed portion 26b of the wound negative electrode core. Thus, the negative current collector 50 is electrically connected to the negative electrode plate 26. The negative current collector 50 is disposed on the opposite side of the electrode body 20 in the thickness direction. Figure 1 The negative electrode receiving member 58 (on the surface of the paper) is integrally connected with the exposed negative electrode core 26b. The negative electrode current collector 50 is electrically connected to the lower end of the negative electrode 16, which is disposed through the second insulating member 62 on the inner side of the sealing plate 14 in the vertical direction.

[0052] The opening of the outer casing 12 is closed by welding a sealing plate 14 to the opening end.

[0053] (Manufacturing methods for positive electrode plates and secondary batteries)

[0054] Next, use Figures 3-9 The explanation will focus on the manufacturing method of the secondary battery 10, particularly the manufacturing method of the positive electrode plate 22. Figure 3 This is a flowchart illustrating a method for manufacturing a secondary battery 10, representing one embodiment. The method for manufacturing the secondary battery 10 includes a positive electrode plate fabrication step S1, a negative electrode plate fabrication step S2, a winding step S3, and a placement step S4. In the positive electrode plate fabrication step S1, a positive electrode plate 22 is fabricated. In the negative electrode plate fabrication step S2, a negative electrode plate 26 is fabricated. In the winding step S3, an electrode body 20 is fabricated by winding the positive electrode plate 22, the negative electrode plate 26, and the separators 30 and 31 in a stacked state. The electrode body fabrication step comprises the positive electrode plate fabrication step S1, the negative electrode plate fabrication step S2, and the winding step S3. In the placement step S4, the electrode body 20 and a non-aqueous electrolyte are placed inside a housing 12, and a sealing plate 14 is welded to the open end of the housing 12. The positive electrode plate fabrication step S1 and the negative electrode plate fabrication step S2 can be performed in reverse order or simultaneously. Next, the positive electrode plate fabrication step S1 will be described in detail.

[0055] (Positive electrode plate manufacturing process)

[0056] Figure 4 This is a flowchart illustrating a method for manufacturing a positive electrode plate 22, representing one embodiment. The method for manufacturing the positive electrode plate 22 includes a coating and drying step S1a, a compression step S1b, and a cutting step S1c. In this example, the manufacturing method involves simultaneously manufacturing two positive electrode plates 22. First, a pre-cut positive electrode plate 32 is manufactured, having a width equal to the sum of the widths of the two positive electrode plates 22. Figure 5 , Figure 6 ). Figure 5 This is a partial unfolded view of the positive electrode plate 32 along its length before it is cut. Figure 6 yes Figure 5 AA sectional view. For example... Figure 5 , Figure 6 As shown, Figure 4 The coating and drying process S1a and the compression process S1b shown are performed with the positive electrode core exposed portions 32b respectively arranged on both ends of the main body portion 32a of the positive electrode plate 32 before cutting. In the coating and drying process S1a, the positive electrode active material layer 34 and the protective layer 25 are coated onto the positive electrode core 33.

[0057] Figure 7 (a) represents the state of the positive electrode plate 32 before the coating and drying process and before the compression process in one embodiment. Figure 6 The enlarged image of the upper half is quite similar to the image. Figure 7(b) represents the state of the positive electrode plate 32 after the coating and drying process and the compression process in one embodiment. Figure 6 The enlarged view of the upper half is quite similar to the image shown. In the coating of the positive electrode active material layer 34 and the protective layer 25, as... Figure 7 As shown in (a), in the protective layer 25, the portion of the core exposed portion P extends into the width direction ( Figure 7 The portion inside the left and right directions forms a line along the length direction between the center A1 in the width direction and the inner part in the left and right directions. Figure 7 A raised portion 25a extends from the inner side of the paper (in the inward direction). At this time, the outer end of the raised portion 25a in the width direction is located closer to the inner side in the width direction than the exposed core portion side P. The outer surface in the thickness direction from this outer end in the width direction to the exposed core portion side P can be located closer to the positive electrode core 33 than the outer surface in the thickness direction inside the protective layer 25 in the width direction, or it can be formed as a flat surface at the same thickness direction position as the outer surface in the thickness direction inside the width direction of the protective layer 25. After the above coating, the positive electrode active material layer 34 and the protective layer 25 are dried. For example, LiNi is used as the positive electrode active material. 0.35 Co 0.35 Mn 0.30A positive electrode active material layer slurry is prepared by mixing lithium-containing metal composite oxide (represented by O2), carbon black as a conductive material, and polyvinylidene fluoride (PVDF) as a binder. Furthermore, a protective layer slurry containing inorganic oxides and a binder is prepared to form a protective layer 25. The positive electrode active material layer slurry and the protective layer slurry are then applied to both sides of the positive electrode core 33 using a die-coating machine. Applying the positive electrode active material layer slurry and the protective layer slurry is equivalent to applying the positive electrode active material layer and the protective layer. For example, a protective layer supply port is provided at the upper part of the die head of the die-coating machine. The positive electrode active material layer slurry supplied from the positive electrode active material layer supply section and the protective layer slurry supplied from the protective layer supply port are guided towards the nozzle of the die head. A pad provided at the nozzle is used to spray the positive electrode active material layer slurry and the protective layer slurry to different positions in the width direction of the positive electrode core 33. Furthermore, the positive electrode active material layer slurry is coated at the central portion of the positive electrode core 33 in the width direction, and a protective layer slurry is coated at both ends of the area where the positive electrode active material layer slurry is coated in the width direction. Furthermore, the thickness of the protective layer 25 is made smaller than the thickness of the positive electrode active material layer 34. Moreover, in each protective layer 25, a raised portion 25a is formed between the portion that enters the inner side in the width direction compared to the exposed end P of the core and the center A1 in the width direction. For example, a first opening for ejecting the positive electrode active material layer slurry and two second openings for ejecting the protective layer slurry are formed on the pad as openings at the opening ends of the ejector ports, and one or both of the shape of the second openings and the ejection flow rate of each slurry are changed. Thus, a pre-cut positive electrode plate is formed before the drying process, with the raised portion of the protective layer slurry formed at a predetermined position. Then, the pre-cut positive electrode plate is dried using a dryer, thereby forming a pre-cut positive electrode plate 32 before the compression process.

[0058] Figure 8 In one example of the implementation, in the compression process S1b ( Figure 4 A simplified diagram of the stamping press 40 used in ). Figure 9 This is a front view of the compression roller 41 that constitutes the press 40. It is used in the compression process S1b. Figure 8 , Figure 9 A stamping press 40. The stamping press 40 includes a pair of opposing compression rollers 41. For example... Figure 9 As shown, a pair of compression rollers 41 each include: a central pressing portion 42, which presses against the positive electrode active material layer 34 ( Figures 5-7Compression is performed; and two end pressing portions 43 are provided at both ends of the middle pressing portion 42 and have a diameter larger than that of the middle pressing portion 42. The end pressing portions 43 are used to compress the protective layer 25. A pair of compression rollers 41 are rotatably arranged in a state opposite to each other. In the compression process S1b, the pre-cut positive electrode plate 32, after drying and before the compression process, is passed between a pair of compression rollers 41, thereby compressing the pre-cut positive electrode plate 32. At this time, the pre-cut positive electrode plate 32 is compressed by pressing the raised portion 25a formed by the coating and drying process and the positive electrode active material layer 34. Thus, as Figure 7 As shown in (b), a pre-cut positive electrode plate 32 is manufactured, having a main body 32a on which a positive electrode active material layer 34 is formed on the positive electrode core 33, and a positive electrode core exposed portion 32b where the positive electrode core 33 is exposed without the formation of a positive electrode active material layer. A protective layer 25 is formed in the region of the positive electrode core exposed portion 32b adjacent to the positive electrode active material layer 34. Figure 7 In the positive electrode plate 32 before cutting (b), the raised portion 25a of the protective layer 25 ( Figure 7 (a) is compressed so that the outer surface in the thickness direction becomes approximately flat. At this time, the thickness of the protective layer 25 is smaller than the thickness of the positive electrode active material layer 34. Since the positive electrode plate 32 is manufactured as described above before cutting, as will be explained later, it is possible to prevent the formation of wrinkles in the positive electrode plate 22 and to prevent misalignment of the positive electrode plate 22 in the case of forming a wound electrode body 20.

[0059] After the compression process S1b, in the cutting process S1c ( Figure 4 In the width direction of the main body 32a, the center A2 ( Figure 7 (b) along the length direction Figure 7 (b) is cut along the inside-out direction of the paper to form two positive plates 22. Figure 2 For example, the cutting process S1c is performed using a slitting machine. In the slitting machine, two bladed rollers with slitting blades formed on the outer circumferential surface of the cylindrical rollers are rotatably arranged opposite each other, so that the positive electrode plate 32 before cutting passes between the two bladed rollers, thereby cutting the positive electrode plate 32 before cutting at the center A2 in the width direction, and producing two positive electrode plates 22.

[0060] In the winding process, a wound electrode body 20 is formed by stacking and winding the positive electrode plate 22, the negative electrode plate 26, and the separators 30 and 31 manufactured as described above. Figure 2 Then, after the configuration process S4 ( Figure 3 ), manufacture secondary batteries 10.

[0061] (Effect)

[0062] According to the manufacturing methods of the positive electrode plate 22 and the secondary battery 10 described above, when coating the positive electrode active material layer 34 and the protective layer 25 onto the positive electrode core 33, a raised portion 25a is formed in the protective layer 25 between the portion that enters the inner side in the width direction relative to the exposed end P of the core and the center A1 in the width direction. Then, the positive electrode active material layer 34 and the protective layer 25 are dried. Furthermore, after coating and drying, the protective layer 25 and the positive electrode active material layer 34 are compressed by pressing the raised portion 25a and the positive electrode active material layer 34. Therefore, when the positive electrode active material layer 34 is compressed, the raised portion 25a of the protective layer 25 is compressed. Thus, in the positive electrode core 33, not only is the portion where the positive electrode active material layer 34 is provided pressed and elongated along the plate thickness direction, but the portion where the raised portion 25a is provided is also pressed and elongated along the plate thickness direction. Therefore, the elongation difference between the portions of the positive electrode cores 23 and 33 where the positive electrode active material layers 24 and 34 are located and the exposed portions 22b and 32b of the positive electrode cores can be reduced, thus suppressing the bending of the positive electrode plate 22. Therefore, the formation of wrinkles in the exposed portions 22b and 32b of the positive electrode cores during the compression of the positive electrode active material layers 24 and 34 can be suppressed, and the occurrence of winding misalignment of the positive electrode plate 22 during the winding process of the electrode body 20 can also be suppressed. Furthermore, the raised portion 25a of the protective layer 25 is located between the portion that enters the inner side in the width direction relative to the exposed portion side P of the core and the center A1 in the width direction. Therefore, by pressing and compressing the protective layer 25 at this position, the formation of uneven deformation portions, i.e., wrinkles, at the protective layer 25 formation portion of the positive electrode core 23 can be suppressed.

[0063] Hereinafter, the manufacturing method of the positive electrode plate 22 of the present disclosure will be further described through examples, and the manufacturing method of the positive electrode plate of Comparative Examples 1 to 3 will also be described.

[0064] <Example>

[0065] [Making the positive electrode plate]

[0066] The positive electrode active material is LiNi 0.35 Co 0.35 Mn 0.30A lithium-containing metal composite oxide (represented by O2), carbon black as a conductive material, and polyvinylidene fluoride (PVDF) as a binder are mixed in a solid component mass ratio of 96:3:1, and the mixture is then kneaded to prepare a positive electrode active material layer slurry. Additionally, a protective layer slurry containing inorganic oxides and a binder is prepared to form a protective layer 25. This positive electrode active material layer slurry and the protective layer slurry are coated onto both sides of a positive electrode core 33 made of aluminum foil with a thickness of 15 μm. After the coating is dried, it is compressed using a compression roller, thereby producing a pre-cut positive electrode plate 32. Then, the pre-cut positive electrode plate 32 is cut at the center in the width direction to a predetermined electrode size, producing a positive electrode plate 22 with a positive electrode active material layer 24 formed on both sides of the positive electrode core 33. In the pre-cut positive electrode plate 32, the width W1 of the positive electrode active material layer 24 is... Figure 5 The thickness is 179mm, and the width W2 of the protective layer 25 is 179mm. Figure 5 The width W3 of the positive electrode core exposed portion 32b, including the protective layer 25 formation portion, is 7.0 mm. Figure 5 The thickness is 15 mm. Additionally, the thickness D1 of one side of the positive electrode active material layer 34 after compression treatment is 25 μm. Furthermore, as... Figure 7 As shown, a protective layer 25 is applied, and in each protective layer 25, a layer is formed between the portion of the core exposed portion side end P that enters the inner side in the width direction and the width direction center A1, along the length direction (along... Figure 7 The raised portion 25a extends in the inward direction of the paper surface. Furthermore, after the protective layer 25 is applied and before the compression process, the distance L1 from the raised portion 25a to the exposed core side end P is... Figure 7 (a) is set to 2mm to 3mm, and the maximum thickness D2 of the single-sided protective layer 25 before compression treatment is ( Figure 7 (a) In the embodiment, the thickness of the protective layer to the top of the raised portion is 20 μm. Furthermore, the thickness D3 of the single-sided protective layer 25 after compression treatment is... Figure 7 (b) is 15 μm.

[0067] Table 1 shows the width W2, distance L1, and thicknesses D2 and D3 of the protective layer 25 of the positive electrode plate 22 or the positive electrode plate 32 before cutting in the manufacturing methods of the embodiments and Comparative Examples 1 to 3 described below. Table 1 also shows the amount of warping (bending) at the center of the width direction of the positive electrode plate 22 in the manufacturing methods of the embodiments and Comparative Examples 1 to 3, that is, the thickness direction distance from the thickness direction center at the center position in the length direction to the thickness direction center at one end in the length direction, and the results of the presence or absence of wrinkles (protective layer wrinkles) at the protective layer 25 forming portion of the positive electrode core 23.

[0068] [Table 1]

[0069]

[0070] <Comparative Example 1>

[0071] Figure 10 (a) represents the state of the positive electrode plate 63 before the compression process in the manufacturing method of Comparative Example 1, before it is cut off. Figure 6 The image corresponding to the enlarged upper part. Figure 10 (b) represents the state after the compression process of the positive electrode plate 63 before it is cut off in the manufacturing method of Comparative Example 1. Figure 6 The upper half of the enlarged view corresponds to the image. In Comparative Example 1, as shown... Figure 10 As shown in (a), when the positive electrode active material layer 34 and the protective layer 25 are coated on the positive electrode plate 63 before cutting, no protrusions are formed in the protective layer 25, making the outer surface of the protective layer 25 in the thickness direction approximately flat. Then, in the compression process, the compression roller is used to compress only the portion where the positive electrode active material layer 34 is provided, thereby achieving the desired effect. Figure 10 As shown in (b), the positive electrode plate 63 before cutting after the compression process was obtained. Furthermore, in Comparative Example 1, the maximum thickness D2 of the single-sided protective layer 25 before compression was 15 μm. The positive electrode plate was fabricated with the other structures the same as in the embodiment.

[0072] <Comparative Example 2>

[0073] Figure 11 (a) represents the state of the positive electrode plate 64 before the compression process in the manufacturing method of Comparative Example 2, before it is cut off. Figure 6 The image corresponding to the enlarged upper part. Figure 11 (b) represents the state after the compression process of the positive electrode plate 64 before it is cut off in the manufacturing method of Comparative Example 2. Figure 6 The upper half of the enlarged view corresponds to the image. In Comparative Example 2, as shown... Figure 11 As shown in (a), when the positive electrode active material layer 34 and the protective layer 25 are coated on the positive electrode plate 64 before cutting, a continuous and longitudinally extending section is formed in the protective layer 25 near the exposed core end P. Figure 11 The raised portion 25b extends in the inward direction of the paper surface. Furthermore, during the compression process, the protective layer 25 and the positive electrode active material layer 34 are compressed using a compression roller by pressing the raised portion 25b and the positive electrode active material layer 34, thereby... Figure 11 As shown in (b), a positive electrode plate 64 before cutting after the compression process was obtained. In Comparative Example 2, after the protective layer 25 was coated and before the compression process, the distance L1 from the raised portion 25b to the exposed end P of the core was 0 mm to 1 mm. Furthermore, the thickness D3 of the single-sided protective layer 25 after the compression process was 14 μm. A positive electrode plate was fabricated with the other structures the same as in the embodiment.

[0074] <Comparative Example 3>

[0075] Figure 12 (a) represents the state of the positive electrode plate 65 before the compression process in the manufacturing method of Comparative Example 3, before it is cut off. Figure 6 The image corresponding to the enlarged upper part. Figure 12 (b) represents the state after the compression process of the positive electrode plate 65 before it is cut off in the manufacturing method of Comparative Example 3. Figure 6 The upper half of the enlarged view corresponds to the image. In Comparative Example 3, as shown... Figure 12 As shown in (a), when the positive electrode plate 65 is coated with the positive electrode active material layer 34 and the protective layer 25 before cutting, a continuous and longitudinally extending layer ( ) is formed near the positive electrode active material layer side end Q in the protective layer 25. Figure 12 The raised portion 25c extends in the inward direction of the paper surface. Furthermore, during the compression process, the protective layer 25 and the positive electrode active material layer 34 are compressed using a compression roller by pressing the raised portion 25c and the positive electrode active material layer 34, thereby... Figure 12 As shown in (b), a positive electrode plate 65 before cutting after the compression process was obtained. In Comparative Example 3, after the protective layer 25 was coated and before the compression process, the distance L1 from the raised portion 25c to the exposed end P of the core was 6 mm to 7 mm. Furthermore, the thickness D3 of the single-sided protective layer 25 after the compression process was 14 μm. A positive electrode plate was fabricated with other structures identical to those in the embodiment.

[0076] [Evaluation Methods and Results]

[0077] The amount of warpage (bending) and the presence or absence of wrinkles at the protective layer 25 of positive electrode plates of a certain length manufactured using the four manufacturing methods of the above-described embodiments and Comparative Examples 1 to 3 were evaluated. According to the evaluation results shown in Table 1, in the embodiments, the amount of warpage was reduced to 9 mm. In addition, in the embodiments, no wrinkles were found at the protective layer 25 forming portion of the positive electrode core 33. It can be seen that by reducing warpage or eliminating wrinkles in this way, it is less likely that winding misalignment of the positive electrode plate will occur when forming a wound electrode body.

[0078] On the other hand, in Comparative Example 1, as shown in Table 1, the warping increased to 16 mm. This is believed to be because, in Comparative Example 1, no protrusion was formed in the protective layer 25, and the protective layer 25 was not compressed. Therefore, the difference in elongation between the portion of the positive electrode core 33 where the positive electrode active material layer 34 is located and the portion where the protective layer 25 is located increased. On the other hand, in Comparative Example 1, since the protective layer 25 was not compressed, no wrinkles were found at the formation portion of the protective layer 25 in the positive electrode core 33, as shown in Table 1.

[0079] Figure 13AThis is a schematic diagram showing the positive electrode plate 22 manufactured by the manufacturing method of the embodiment in its state after the cutting process. Figure 13B This is a schematic diagram showing the positive electrode plate 46 manufactured by the manufacturing method of Comparative Example 1 in its state after the cutting process. Figure 13A As shown, in the manufacturing method of this embodiment, the elongation difference caused by the compression process between the portion of the positive electrode plate 22 where the positive electrode active material layer 24 is provided and the portion where the protective layer 25 is provided can be reduced, thus enabling the positive electrode plate 22 to achieve a greater elongation in the width direction ( Figure 13A The length direction at both ends (up and down direction) Figure 13A The difference in length (in the left and right directions) of the positive electrode plate 22 can be reduced. Therefore, the difference in length from one end in the thickness direction ( Figure 13A When viewed from the surface of the paper, the shape is a long rectangular strip with high shape accuracy. Therefore, it can be seen that the winding misalignment of the positive electrode 22 can be prevented when the electrode body 20, including the positive electrode 22, is formed into a wound shape.

[0080] On the other hand, such as Figure 13B As shown, in the manufacturing method of Comparative Example 1, in the positive electrode plate 46, the difference in elongation caused by the compression process is significant between the portion where the positive electrode active material layer 24 is provided and the portion where the protective layer 25 is provided. The portion where the positive electrode active material layer 24 is provided exhibits greater elongation compared to the portion where the protective layer 25 is provided. Therefore, the width direction of the positive electrode plate 46 ( Figure 13B The length direction at both ends (up and down direction) Figure 13B The difference in length in the left and right directions increases, thus, the shape of the positive electrode plate 46, when viewed from one end in the thickness direction, is deformed from a long rectangular strip into an approximate arc shape with the positive electrode active material layer 24 on the inside. Figure 13B The bending of the positive electrode plate 46 is exaggerated in the image. As described above, the positive electrode plate 46 is deformed, which makes it easier for misalignment of the positive electrode plate 46 to occur in the case where the electrode body 20 is formed in a wound shape including the positive electrode plate 46.

[0081] Furthermore, in Comparative Example 2, since the raised portion 25b of the protective layer 25 is compressed, the difference in elongation between the portion of the positive electrode core 33 where the positive electrode active material layer 34 is provided and the portion where the protective layer 25 is provided is reduced. As a result, as shown in Table 1, the amount of warpage can be reduced to 9 mm. On the other hand, in Comparative Example 2, wrinkles were generated near the core exposed portion side P of the protective layer 25 forming portion of the positive electrode core 33. The reason for this is believed to be that since the raised portion 25b of the protective layer 25 is continuous with the core exposed portion side P of the protective layer 25, the positive electrode core 33 is pressed near the core exposed portion side P of the protective layer 25 forming portion during the compression process. More specifically, it is believed that because the thickness of the portion including the raised portion 25b near the core exposed end P of the protective layer 25 is significantly different from the thickness of the positive electrode core 33, the positive electrode core 33 is pressed near the core exposed end P of the protective layer 25, resulting in a greater difference in elongation on both sides of the positive electrode core 33, with the core exposed end P as the boundary. Therefore, it can be considered that wrinkles are formed in the positive electrode core 33 near the core exposed end P.

[0082] In Comparative Example 3, similarly to Comparative Example 2, the raised portion 25c of the protective layer 25 was compressed. However, unlike Comparative Example 2, the raised portion 25c was adjacent to the positive electrode active material layer 34. Consequently, in Comparative Example 3, the difference in elongation between the portion of the positive electrode core 33 where the positive electrode active material layer 34 is located and the portion where the protective layer 25 is located, which is further away from the positive electrode active material layer 34 in the width direction, increased. As a result, as shown in Table 1, the warping amount increased to 14 mm. Furthermore, in Comparative Example 3, wrinkles were generated near the boundary between the portion where the protective layer 25 was formed and the portion where the positive electrode active material layer 34 was formed. This is believed to be because the raised portion 25c of the protective layer 25 is continuous with the side end Q of the positive electrode active material layer. During the compression process, the positive electrode core 33 is pressed at both the portion where the positive electrode active material layer 34 is located and the portion where the raised portion 25c is located. More specifically, it is believed that the thickness of the portion including the raised portion 25c at the positive electrode active material layer side Q of the protective layer 25 differs significantly from the thickness of the positive electrode active material layer 34. Therefore, due to the pressure exerted on the positive electrode core 33 near the positive electrode active material layer side Q of the protective layer 25 and on the portion forming the positive electrode active material layer 34, the difference in elongation between the two sides of the boundary between the protective layer 25 and the positive electrode active material layer 34 increases. Consequently, it can be considered that wrinkles are generated near this boundary.

[0083] In the above embodiments, the case where the positive electrode plate 22 has a positive electrode active material layer 24 formed on both sides of the positive electrode core 23 has been described. However, the positive electrode plate manufactured by the manufacturing method of this disclosure is not limited to such a structure. The positive electrode plate may also be a structure in which the positive electrode active material layer is formed only on one side of the positive electrode core.

[0084] Explanation of reference numerals in the attached figures

[0085] 10. Non-aqueous electrolyte secondary battery (secondary battery); 12. Outer casing; 14. Sealing plate; 15. Positive terminal; 16. Negative terminal; 20. Electrode body; 22. Positive electrode plate; 22a. Main body; 22b. Exposed part of positive electrode core; 23. Positive electrode core; 24. Positive electrode active material layer; 25. Protective layer; 25a-25c. Raised parts; 26. Negative electrode plate; 26a. Main body; 26b. Exposed part of negative electrode core; 27. Negative electrode core; 28. Negative electrode active material layer; 30. 1. Separator; 32. Positive electrode plate before cutting; 32a. Main body; 32b. Positive electrode core exposed part; 33. Positive electrode core; 34. Positive electrode active material layer; 40. Press; 41. Compression roller; 42. Intermediate pressing part; 43. End pressing part; 46. Positive electrode plate; 47. Positive electrode current collector; 48. Positive electrode receiving component; 50. Negative electrode current collector; 58. Negative electrode receiving component; 60. Insulating tape; 61. First insulating component; 62. Second insulating component; 63-65. Positive electrode plate before cutting.

Claims

1. A method for manufacturing a positive electrode plate for a non-aqueous electrolyte secondary battery, the positive electrode plate comprising a main body portion on which a positive electrode active material layer is formed, and a core exposure portion where the positive electrode core is exposed and no positive electrode active material layer is formed, wherein, The positive electrode plate of the non-aqueous electrolyte secondary battery has a protective layer formed in the region adjacent to the positive electrode active material layer in the exposed part of the core. The method for manufacturing the positive electrode plate for the non-aqueous electrolyte secondary battery includes: In the coating and drying process, the positive electrode active material layer and the protective layer are coated onto the positive electrode core with uniform thickness. After coating the protective layer with a raised portion that forms an outer side in the thickness direction between the portion of the protective layer that enters the inner side in the width direction relative to the exposed end of the core and the center in the width direction, the positive electrode active material layer and the protective layer are dried. as well as The compression process involves pressing the raised portion and the positive electrode active material layer formed by the coating and drying process to compress the protective layer and the positive electrode active material layer.

2. The method for manufacturing a positive electrode plate for a non-aqueous electrolyte secondary battery according to claim 1, wherein, The coating and drying process and the compression process are performed with the core exposed portions respectively located on both ends of the main body. The manufacturing method of the positive electrode plate for the non-aqueous electrolyte secondary battery further includes a cutting step, in which, after the compression step, the main body is cut in the center of the width direction to form two positive electrode plates for the non-aqueous electrolyte secondary battery.

3. The method for manufacturing a positive electrode plate for a non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein, The thickness of the protective layer is smaller than the thickness of the positive electrode active material layer.

4. A method for manufacturing a non-aqueous electrolyte secondary battery, wherein, The method for manufacturing the non-aqueous electrolyte secondary battery includes: An electrode body manufacturing process, wherein an electrode body comprising a positive electrode plate, a negative electrode plate, and a separator for a non-aqueous electrolyte secondary battery, manufactured using the manufacturing method according to any one of claims 1 to 3, is produced; and The configuration process involves placing the electrode body and the non-aqueous electrolyte into the outer casing.

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