Non-aqueous electrolyte secondary battery

Abstract

The non-aqueous electrolyte secondary battery comprises: an electrode body formed by overlapping a positive electrode plate, a negative electrode plate and a separator; a square outer body for accommodating the electrode body; a sealing plate; an electrode terminal arranged on the sealing plate; a first collector connected to the electrode terminal between the electrode body and the sealing plate; a second collector connected to the first collector between the electrode body and the side wall of the square outer body; and a tab group extending from the electrode body to one side of the side wall and connected to the second collector, the tab group comprising a positive tab group / negative tab group formed by bundling a plurality of positive tabs / negative tabs extending from the positive electrode plate / negative electrode plate, the tab group being bent in a manner parallel to the side wall on the connection side connected to the second collector, the positive electrode plate comprising a positive electrode core and a positive electrode active material coated on the positive electrode core, the positive electrode tab extending from the positive electrode core, the end of the positive electrode core on the side from which the positive electrode tab extends and the surface near the positive electrode core are covered with a protective layer and the protective layer is exposed, and one end of the negative electrode plate is opposite to the protective layer in the positive electrode plate.

Description

Technical Field

[0001] The present disclosure relates to a non-aqueous electrolyte secondary battery. Background Art

[0002] Non-aqueous electrolyte secondary batteries, such as lithium-ion batteries, have an electrode assembly housed in an outer casing with an opening, which is sealed with a sealing plate. The electrode assembly consists of a stacked positive electrode and a negative electrode with a separator interposed between them.

[0003] For example, Patent Document 1 discloses: an electrode body having a structure in which multiple positive plates and multiple negative plates are stacked with separators interposed between the positive and negative plates; and an electrode body formed by overlapping and winding elongated positive and negative plates with separators interposed between the positive and negative plates. In an electrode body having a structure in which multiple positive plates and multiple negative plates are stacked with separators interposed between the positive and negative plates, a positive electrode tab for current collection extends from each positive plate, and a negative electrode tab for current collection extends from each negative plate. In the wound electrode body, multiple positive electrode tabs extend from the elongated positive plate, and multiple negative electrode tabs extend from the elongated negative plate. Due to the winding process, the multiple positive electrode tabs are arranged facing each other, and the multiple negative electrode tabs are similarly arranged facing each other. Patent Document 2 also discloses an electrode body having a structure in which a plurality of positive plates and a plurality of negative plates are stacked with separators interposed between the positive plates and the negative plates, wherein the positive electrode tabs extend from the positive plates and the negative electrode tabs extend from the negative plates.

[0004] Furthermore, in all types of batteries, the capacity of the negative electrode active material is designed to be greater than that of the positive electrode active material. In batteries where the positive and negative plates are stacked backward, the area of ​​the positive plate's active material coating is designed to fall within the area of ​​the negative plate's active material coating, and the negative electrode active material coating extends beyond (protrudes beyond) the positive electrode active material coating. Furthermore, to maximize battery capacity, the areas of the positive and negative electrode active material coatings are designed to be as large as possible.

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-175407

[0006] Patent Document 2: China Patent Authorization Announcement No. 100590927 Summary of the Invention

[0007] As disclosed in Patent Documents 1 and 2, in batteries where tabs for current collection are formed on the positive and negative plates, burrs may be generated when portions of the positive and negative plates are cut to form the tabs. Burrs are particularly prone to forming corners, and the root of the electrode tab corresponds to a region prone to burr formation.

[0008] However, in order to increase battery capacity, the area of ​​the positive electrode active material coating on the positive electrode plate is designed to be as large as possible, resulting in the root of the positive electrode tab overlapping with the negative electrode plate. Although the two are separated by a separator, if a burr forms at the root of the positive electrode tab, there is a problem: since the burr is metal, it can break through the separator and come into contact with the negative electrode plate, potentially causing a short circuit.

[0009] The non-aqueous electrolyte secondary battery involved in the present disclosure is constructed as follows. The non-aqueous electrolyte secondary battery comprises: an electrode body, wherein the electrode body comprises a positive electrode plate and a negative electrode plate; a square outer body, wherein the square outer body has an opening and accommodates the electrode body; a sealing plate, wherein the sealing plate closes the opening; an electrode terminal, wherein the electrode terminal is arranged on the sealing plate; a first current collector, wherein the first current collector is arranged between the electrode body and the sealing plate and is connected to the electrode terminal; a second current collector, wherein the second current collector is arranged between the electrode body and the side wall of the square outer body and is connected to the first current collector; and a tab group, wherein the tab group extends from the electrode body to one side of the side wall and is connected to the second current collector, the second current collector being composed of a flat plate having a surface parallel to the side wall, the tab group having a positive tab group and a negative tab group. The positive electrode tab group is a positive electrode tab group, and on the side of the connection portion connected to the second current collector, the tab group is bent in a manner parallel to the side wall, the positive electrode tab group is composed of a plurality of positive electrode tabs extending from the positive electrode plate, and the negative electrode tab group is composed of a plurality of negative electrode tabs extending from the negative electrode plate. The positive electrode plate includes a positive electrode core and a positive electrode active material coated on the positive electrode core, the positive electrode tab extends from the positive electrode core, and the end of the positive electrode core on the side from which the positive electrode tab extends and the surface near the end are covered with a protective layer containing an insulating material and the protective layer is exposed, in the electrode body, the positive electrode plate and the negative electrode plate are overlapped with a separator sandwiched between the positive electrode plate and the negative electrode plate, and one end of the negative electrode plate is opposite to the protective layer in the positive electrode plate.

[0010] Alternatively, the positive electrode tab group is located on one end surface of the electrode body, and the negative electrode tab group is located on the other end surface of the electrode body.

[0011] Preferably, the distance between the end of the protective layer and one end of the negative electrode plate is greater than or equal to 0.1 mm in a plan view.

[0012] Alternatively, the protective layer is further provided on a portion of the positive electrode tab.

[0013] Alternatively, the insulating material may be an inorganic oxide.

[0014] In the nonaqueous electrolyte secondary battery of the present disclosure, the end portion of the positive electrode plate where the positive electrode tab protrudes is covered with a protective layer, and the end portion of the negative electrode plate faces the protective layer, thereby ensuring high safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a perspective view showing a nonaqueous electrolyte secondary battery according to an embodiment of the present disclosure;

[0016] Figure 2 yes Figure 1 A cross-sectional view of a battery;

[0017] Figure 3 is a diagram showing a second current collector according to an embodiment of the present disclosure;

[0018] Figure 4 is a top view of a positive electrode plate according to an embodiment of the present disclosure;

[0019] Figure 5 is a top view of a negative electrode plate according to an embodiment of the present disclosure;

[0020] Figure 6 is a top view of an electrode body according to an embodiment of the present disclosure;

[0021] Figure 7 is a diagram schematically showing the positional relationship among a positive electrode plate, a negative electrode plate, and a separator according to an embodiment of the present disclosure;

[0022] Figure 8 is a diagram schematically showing the positional relationship among the positive electrode plate, the negative electrode plate, and the separator according to a comparative embodiment;

[0023] Figure 9 This is a diagram showing the vicinity of the connection between the second current collector and the tab assembly before the tab assembly is bent;

[0024] Figure 10 A diagram showing the vicinity of the connection between the second current collector and the tab assembly after the tab assembly is bent;

[0025] Figure 11 is a perspective view of the electrode body showing the tab group being connected to the second current collector before the tab group is bent;

[0026] Figure 12 is a diagram showing an electrode body group including a plurality of electrode bodies;

[0027] Figure 13 This figure shows a plurality of electrode assembly groups and a sealing plate connected to each other via a first current collector and a second current collector. DETAILED DESCRIPTION

[0028] Below, embodiments of the present disclosure are described in detail based on the accompanying drawings. The following description of preferred embodiments is merely an example of the present disclosure and is not intended to limit the present disclosure, its applications, or its uses. In the following drawings, components having substantially the same functions are denoted by the same reference numerals for simplicity of description.

[0029] <Overall battery structure>

[0030] Figure 1 It is a perspective view showing the nonaqueous electrolyte secondary battery according to the present disclosure. Figure 2 Cut parallel to the paper Figure 1 A cross-sectional view of a battery. Figure 1 、 Figure 2 As shown, the nonaqueous electrolyte secondary battery 20 includes a battery case 100 composed of a square outer casing 1 having a bottom and a square cylindrical shape with an opening, and a sealing plate 2 that closes the opening of the square outer casing 1 .

[0031] The rectangular outer body 1 comprises a bottom 1a, a pair of first side walls 1b and 1c, and a pair of second side walls 1d and 1e. The pair of first side walls 1b and 1c are arranged in mutually opposing directions. The pair of second side walls 1d and 1e are arranged in mutually opposing directions. The pair of first side walls 1b and 1c are perpendicular to the long sides of the sealing plate 2, and the area of ​​the pair of first side walls 1b and 1c is smaller than the area of ​​the pair of second side walls 1d and 1e.

[0032] The electrode body 3 and the electrolyte are housed together in the square outer body 1, and the electrode body 3 includes a positive electrode plate 4 and a negative electrode plate 5. In the present embodiment, the electrode body 3 is a flat electrode body formed by winding the positive electrode plate 4 and the negative electrode plate 5 in such a manner that a separator is sandwiched between the positive electrode plate 4 and the negative electrode plate 5. The winding axis of the electrode body 3 extends in a manner perpendicular to the first side walls 1b, 1c and parallel to the second side walls 1d, 1e. It should be noted that the electrode body 3 is not limited to a wound electrode body. For example, it can also be a stacked electrode body formed by stacking a plurality of positive electrode plates 4 and negative electrode plates 5 in such a manner that a separator is sandwiched between the positive electrode plate 4 and the negative electrode plate 5.

[0033] It should be noted that in Figure 2In the figure, reference numeral 10 denotes an external insulating member disposed between the sealing plate 2 and the positive electrode terminal 8, and reference numeral 12 denotes an external insulating member disposed between the sealing plate 2 and the negative electrode terminal 9. Reference numeral 11 denotes an internal insulating member disposed between the sealing plate 2 and the first positive electrode current collector 61, and reference numeral 13 denotes an internal insulating member disposed between the sealing plate 2 and the first negative electrode current collector 71. Reference numeral 14 denotes a box-shaped or bag-shaped insulating sheet disposed inside the square outer body 1 and housing the electrode body 3. Reference numeral 15 denotes an electrolyte injection hole provided on the sealing plate 2. Reference numeral 16 denotes a sealing member for sealing the electrolyte injection hole 15. Reference numeral 17 denotes a vent valve provided on the sealing plate 2.

[0034] In the nonaqueous electrolyte secondary battery 20, one side of the electrode assembly 3 in the direction in which the winding axis extends is the positive electrode side, and the other side is the negative electrode side.

[0035] <Electrode body structure>

[0036] like Figure 4 As shown, the positive electrode plate 4 is in the shape of a long strip, and the positive electrode plate 4 has an area on both sides of the positive electrode core (such as aluminum foil) where a positive electrode active material layer 4a is formed. A plurality of positive electrode tabs 4b protrude from the positive electrode core at one end in the short side direction of the positive electrode plate 4 in a convex shape. The surface of the positive electrode core at one end in the short side direction of the positive electrode plate 4 and its vicinity is covered with a protective layer 4c. That is, a protective layer 4c is provided with a certain width from one side (end) extending in the long side direction of the positive electrode plate 4 toward the long side center axis direction of the positive electrode plate 4. In addition, a protective layer is also provided at the root portion of the positive electrode tab 4b. The protective layer 4c contains an insulating material. For example, the protective layer 4c can be set as an insulating layer made of resin, or the protective layer 4c can be set as a layer containing an inorganic oxide, i.e., ceramic and a resin binder. As an example of the protective layer 4c, a layer containing aluminum oxide powder, a carbon material as a conductive material, and polyvinylidene fluoride as a binding material can be cited.

[0037] like Figure 5 As shown, the negative electrode plate 5 is in the form of a long strip, and has regions on both sides of a negative electrode core (e.g., copper foil) where negative active material layers 5a are formed. A plurality of negative electrode tabs 5b protrude from the negative electrode core at one end of the negative electrode plate 5 in the short direction.

[0038] like Figure 6 As shown, the positive electrode plate 4 and the negative electrode plate 5 are stacked with a separator interposed therebetween, and the electrode body 3 is formed by winding them. In the electrode body 3, the winding axis is along the direction connecting the positive electrode tab group 40 and the negative electrode tab group 50 ( Figure 6The positive electrode tab group 40 is located on one end face of the electrode body 3 perpendicular to the winding axis, and the negative electrode tab group 50 is located on the other end face opposite to the one end face. This positioning relationship easily prevents short circuits within the battery.

[0039] Next, use Figure 7 、 Figure 8 The positional relationship between the positive electrode plate 4 and the negative electrode plate 5 in the electrode assembly 3 will be described. Figure 7 Schematically shows the positional relationship among the positive electrode plate 4 , the negative electrode plate 5 , and the separator 95 in this embodiment. Figure 8 This is a diagram schematically showing the positional relationship among the positive electrode plate 4 , the negative electrode plate 52 , and the separator 95 in a comparative embodiment.

[0040] As described in the background art, in a battery structure in which the positive and negative plates are overlapped, the active material coating area of ​​the positive plate is designed to fall within the active material coating area of ​​the negative plate, and the coating area of ​​the negative active material is designed to exceed (protrude) the coating area of ​​the positive active material. When performing the above design, in order to reliably ensure that the coating area of ​​the negative active material exceeds the coating area of ​​the positive active material, as shown in FIG. Figure 8 As shown, the negative electrode plate 52 is typically arranged so that the end (one end) 52e of the negative electrode plate 52, opposite to the end 52d from which the negative electrode tab 52b extends, is positioned further outward than the end 4d of the positive electrode plate 4 from which the positive electrode tab 4b extends (the end of the protective layer 4c on the positive electrode plate 4). This arrangement ensures that, even if the position of the one end 52e of the negative electrode plate 52 is slightly offset relative to the positive electrode plate 4 during the manufacturing process (winding process), the portion coated with the negative electrode active material reliably extends beyond the portion coated with the positive electrode active material.

[0041] It should be noted that the same portion as the protective layer 4c provided on the positive electrode plate 4 is also provided at the root portion of the positive electrode tab 4b. Figure 8 In the embodiment, one end 52e of the negative electrode plate 52 is located between the upper end 4f of the protective layer provided on the positive electrode tab 4b and the end 4d of the positive electrode plate 4. Furthermore, one end 95e of the separator 95 faces the negative electrode tab 52b of the negative electrode plate 52, and the other end 95d faces the positive electrode tab 4b of the positive electrode plate 4. Thus, the separator 95 completely covers the positive electrode active material layer 4a and the negative electrode active material layer 52a.

[0042] However, while strengthening position control during winding results in an overly safe setting for positional accuracy in the manufacturing process, the safety design conditions remain unchanged. Furthermore, when forming the positive electrode tab, the base of the tab is the corner, a region prone to burr formation. Therefore, if burrs form at the base of the positive electrode tab 4b, there is a risk that the burrs formed by the positive electrode core could break through the separator 95 and come into contact with the negative electrode plate 52, potentially causing a short circuit.

[0043] Therefore, in this embodiment, if Figure 7 As shown, the position of one end 5e of the negative electrode plate 5 is set on the inner side of the corresponding end 4d of the positive electrode plate 4 (the end of the protective layer 4c), so that the above-mentioned end 5e is opposite to the protective layer 4c of the positive electrode plate 4. Due to the positional relationship as described above, even if there is a burr at the root part of the positive electrode tab, since there is no negative electrode plate 5 at the position opposite to the burr, a short circuit caused by the burr will not occur. Moreover, it is preferred that: when the electrode body 3 is in a state of being wound after being overlapped with the separator 95, when viewed from above (viewed from a direction perpendicular to the surface of the positive electrode plate 4 and the negative electrode plate 5), the distance between the end 4d of the protective layer 4c of the positive electrode plate 4 and one end 5e of the negative electrode plate 5 is set to be greater than 0.1mm. In this way, short circuits caused by burrs can be reliably prevented. If the distance is set to be greater than 0.15mm, short circuits can be more reliably prevented, so it is more preferred.

[0044] Figure 8 The comparison shown and Figure 7 The present embodiment shown is different only in the position of one end portion 5e, 52e of the negative electrode plates 5, 52; other than that, the configuration and structure are the same.

[0045] <Electrode body current collection structure>

[0046] The sealing plate 2 is provided with a positive electrode terminal 8 and a negative electrode terminal 9, which serve as electrode terminals facing the outside. The positive electrode terminal 8 is electrically connected to the positive electrode tab assembly 40 via a positive electrode current collector 6, which is composed of a first positive electrode current collector 61 and a second positive electrode current collector 62. The negative electrode terminal 9 is electrically connected to the negative electrode tab assembly 50 via a negative electrode current collector 7, which is composed of a first negative electrode current collector 71 and a second negative electrode current collector 72.

[0047] The first positive electrode current collector 61 has a roughly L-shaped cross-section and is positioned between the electrode body 3 and the sealing plate 2. Specifically, the first positive electrode current collector 61 comprises a first region extending along the sealing plate 2 and a second region bent from the end of the first region. The second region extends along the first side wall 1b toward the bottom 1a. The first positive electrode current collector 61 is connected to the positive electrode terminal 8. The negative electrode side is structured in the same manner.

[0048] The second positive electrode current collector 62 is positioned between the electrode body 3 and the first side wall 1b of the rectangular outer casing 1. Specifically, the second positive electrode current collector 62 is formed of a flat plate having a surface parallel to the first side wall 1b and extends along the first side wall 1b toward the bottom 1a. The second positive electrode current collector 62 is connected to the first positive electrode current collector 61. The negative electrode side is configured in the same manner.

[0049] Figure 3 The second positive electrode current collector 62 is shown. The second positive electrode current collector 62 is formed by bending a portion of a substantially rectangular flat plate and includes a current collector connecting portion 62a, an inclined portion 62b, and a tab connecting portion 62c. The current collector connecting portion 62a is connected to the first positive electrode current collector 61. The positive electrode tab assembly 40 is connected to the tab connecting portion 62c. The inclined portion 62b connects the current collector connecting portion 62a and the tab connecting portion 62c and is inclined relative to both.

[0050] The collector connecting portion 62a is provided with a recess 62d. The recess 62d is provided with a through hole 62e. The collector connecting portion 62a is joined to the first positive electrode collector 61 in the recess 62d. The second positive electrode collector 62 is further provided with a fuse 66.

[0051] Next, the bending of the positive electrode tab assembly 40 and the connection between the positive electrode tab assembly 40 and the second positive electrode current collector 62 are described. Note that since the negative electrode has almost the same configuration and structure as the positive electrode, only the positive electrode will be described below. Figure 9 The vicinity of the connection between the second positive electrode current collector 62 and the positive electrode tab assembly 40 is shown before the positive electrode tab assembly 40 is bent. Figure 11 The electrode assembly 3 is shown with the positive electrode tab group 40 connected to the second positive electrode current collector 62 and the negative electrode tab group 50 connected to the second negative electrode current collector 72 before the positive electrode tab group 40 and the negative electrode tab group 50 are bent.

[0052] The positive electrode tab assembly 40 is connected to the tab connection portion 62c of the second positive electrode current collector 62. Specifically, Figure 9 As shown, before the positive tab group 40 is bent, the positive tab group 40 is placed on the tab connection portion 62 c of the second positive electrode current collector 62 , and the tab connection portion 62 c and the positive tab group 40 are joined (welded) to form a connection portion 63 .

[0053] Here, as Figure 9 As shown, the positive electrode tab group 40 is close to one side in the width direction of the flat plate constituting the second positive electrode current collector 62 ( Figure 9The connection portion 63 between the positive electrode tab assembly 40 and the tab connection portion 62c is located on the right side of the plate and is connected to the tab connection portion 62c of the second positive electrode current collector 62. That is, the connection portion 63 between the positive electrode tab assembly 40 and the tab connection portion 62c is located close to the root side of the positive electrode tab assembly 40 in the width direction of the plate (one side in the width direction, Figure 9 As a result, when the positive electrode tab assembly 40 is bent, the curved shape near the base of the positive electrode tab assembly 40 can be formed more reliably and stably.

[0054] Figure 10 This figure shows the vicinity of the connection between the second positive electrode current collector 62 and the positive electrode tab group 40 after the positive electrode tab group 40 is bent. By bending the positive electrode tab group 40, it is possible to arrange the first main surface 3a and the second main surface 3b of the electrode body 3 in approximately parallel fashion (see Figure 9 、 Figure 11 ) The tab connection portion 62c of the second positive electrode current collector 62 is oriented approximately perpendicular to the winding axis of the electrode body 3. Specifically, the positive electrode tab assembly 40 is bent parallel to the first side wall 1b on the side of the connection portion 63 connected to the second positive electrode current collector 62. The bent positive electrode tab assembly 40 is secured to the electrode body 3 using tape 80.

[0055] With the above-described configuration, the positive electrode tab assembly 40 can be bent without bending the second positive electrode current collector 62. Thus, a non-aqueous electrolyte secondary battery having a high volume energy density can be manufactured using a simple method.

[0056] It should be noted that, as mentioned above, the configuration of the negative electrode side is the same as that of the positive electrode side. Figure 11 , 72a represents the collector connecting portion, 72b represents the inclined portion, and 72c represents the tab connecting portion.

[0057] The non-aqueous electrolyte secondary battery involved in this embodiment can achieve a battery with high volume energy density without bending the second current collectors 62 and 72 by bending the positive electrode tab group 40 and the negative electrode tab group 50. Since one end 5e of the negative electrode plate 5 is arranged at a position opposite to the protective layer 4c of the positive electrode plate 4, short circuits within the battery can be prevented.

[0058] (Other embodiments)

[0059] The above embodiments are examples of the invention of this application. The invention of this application is not limited to the above examples. Common knowledge, conventional techniques, and known technologies may be combined with the above examples, or portions thereof may be replaced. In addition, improved inventions that can be easily conceived by those skilled in the art are also included in the invention of this application.

[0060] The nonaqueous electrolyte secondary battery 20 may include a plurality of electrode bodies 3 . Figure 12FIG. 3 is a diagram showing an electrode body group 300 including a plurality of electrode bodies 3. Figure 12 As shown, the nonaqueous electrolyte secondary battery 20 includes a plurality (two) of electrode bodies 3. A second current collector 62 is connected to the positive electrode tab group 40 of each electrode body 3. The plurality of electrode bodies 3, 3 are arranged and fixed together with tape 90 to form an electrode body group 300. Figure 13 This figure shows the electrode assembly group 300 and the sealing plate 2 connected to each other by the first positive electrode current collector 61 and the second positive electrode current collector 62 .

[0061] - Explanation of symbols -

[0062] 1 Square outer body

[0063] 1b First side wall (side wall)

[0064] 1c First side wall (side wall)

[0065] 2 Sealing plate

[0066] 3 Electrode body

[0067] 4 positive plates

[0068] 4b positive electrode tab

[0069] 4c protective layer

[0070] 5 Negative plate

[0071] 5b negative electrode tab

[0072] 5e One end of the negative plate

[0073] 8 Positive terminal (electrode terminal)

[0074] 9 Negative terminal (electrode terminal)

[0075] 20 Non-aqueous electrolyte secondary battery

[0076] 40 positive electrode tab group (tab group)

[0077] 50 negative electrode tab set (tab set)

[0078] 61 First positive electrode current collector (first current collector)

[0079] 62 Second positive electrode current collector (second current collector)

[0080] 71 First negative electrode current collector (first current collector)

[0081] 72 Second negative electrode current collector (second current collector)

[0082] 95 diaphragm

Claims

1. A non-aqueous electrolyte secondary battery, characterized in that: The nonaqueous electrolyte secondary battery comprises: An electrode body, the electrode body comprising a positive electrode plate and a negative electrode plate; A square outer casing having an opening and accommodating the electrode body; A sealing plate, the sealing plate seals the opening; An electrode terminal, wherein the electrode terminal is disposed on the sealing plate; a first current collector, the first current collector being arranged between the electrode body and the sealing plate and connected to the electrode terminal; a second current collector, the second current collector being arranged between the electrode body and a side wall of the square outer casing and connected to the first current collector; and a tab group, the tab group extending from the electrode body toward one side of the side wall and connected to the second current collector, The second current collector is composed of a flat plate having a surface parallel to the side wall. The tab group includes a positive tab group and a negative tab group, and the tab group is bent in parallel with the side wall on the connection portion side connected to the second current collector, the positive tab group is formed by bundling a plurality of positive tabs extending from the positive electrode plate, and the negative tab group is formed by bundling a plurality of negative tabs extending from the negative electrode plate. The positive electrode plate includes a positive electrode core and a positive electrode active material coated on the positive electrode core, the positive electrode tab extends from the positive electrode core, and the end of the positive electrode core from which the positive electrode tab extends and the surface near the end are covered with a protective layer containing an insulating material and the protective layer is exposed. In the electrode body, the positive electrode plate and the negative electrode plate are overlapped with a separator interposed between the positive electrode plate and the negative electrode plate. One end of the negative electrode plate is opposite to the protective layer in the positive electrode plate, The second current collector has a current collector connection portion, an inclined portion, and a tab connection portion, the tab connection portion and the positive electrode tab group are joined to form a connection portion, and the connection portion between the positive electrode tab group and the tab connection portion is close to the root side of the positive electrode tab group in the width direction of the flat plate, The first current collector and the second current collector are separately provided, the cross section of the first current collector is approximately L-shaped, the first current collector has a first region arranged along the sealing plate and a second region bent from the end of the first region, the second region extends along the side wall toward the bottom side of the square outer body, and the current collector connecting portion of the second current collector is electrically connected to the second region of the first current collector, The negative electrode plate comprises a negative electrode core and a negative electrode active material coated on the negative electrode core, and the negative electrode tab extends relative to the positive electrode core. The end of the positive electrode plate opposite to the end on the side from which the positive electrode tab extends is opposite to the negative electrode core in the negative electrode plate. The one end of the negative electrode plate is positioned inside the corresponding end of the positive electrode plate, that is, the end of the protective layer. In a plan view, a distance between an end of the protective layer and one end of the negative electrode plate is greater than or equal to 0.1 mm.

2. The non-aqueous electrolyte secondary battery according to claim 1, characterized in that: The positive electrode tab group is located on one end surface of the electrode body, and the negative electrode tab group is located on the other end surface of the electrode body.

3. The non-aqueous electrolyte secondary battery according to claim 1 or 2, characterized in that: The protective layer is also disposed on a portion of the positive electrode tab.

4. The non-aqueous electrolyte secondary battery according to claim 1 or 2, characterized in that: The insulating material is an inorganic oxide.

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