JP2019102361A - Electrode plate and secondary battery - Google Patents

Abstract

To provide a more reliable electrode plate for a secondary battery.SOLUTION: An electrode plate 20 for a secondary battery has: a sheet-like core body 10 including a body part 10e and a tab part 10c protruding from the body part 10e; and an active material layer 12 formed on the body part 10e of the core body 10. A notch 10d is formed on a border between the tab part 10c and the active material layer 12 so as to be across over both of the tab part 10c and the active material layer 12.SELECTED DRAWING: Figure 7

Description

  The present disclosure relates to an electrode plate and a secondary battery.

  Non-aqueous electrolyte secondary batteries, etc. as power supplies for driving electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), etc. A secondary battery is used. These secondary batteries include a positive electrode plate and a negative electrode plate in which an active material layer containing an active material is formed on the surface of a sheet-like core made of metal foil.

  In particular, secondary batteries used for electric vehicles, hybrid electric vehicles and the like are required to further increase the volumetric energy density. In order to increase the volumetric energy density of the secondary battery, a method of increasing the packing density of the active material layer has been proposed. For example, the active material layer formed on the core is compressed using a roll press or the like, whereby the packing density of the active material layer is made high.

  However, when the active material layer formed on the core is compressed, not only the active material layer but also the core is strongly compressed. Thereby, the core is rolled.

  In the compression process, when there is a core exposed portion such as a tab portion where the active material layer is not formed at the end of the electrode plate, the core exposed portion is a portion where the active material layer is formed (active material layer formation Since the thickness is smaller than that of the part), a larger weight is not applied to the part where the active material layer is formed. Therefore, although the active material layer forming portion in the core body is stretched, the core exposed portion is hardly stretched. That is, in the core, a difference in the amount of stretching occurs between the active material layer forming portion and the core exposed portion. Depending on the difference in the amount of extension, wrinkles or cracks may occur in the core, or the electrode plate may be curved.

  In order to cope with this problem, in the compression process described in Patent Document 1, the core exposed portion of the core of the electrode plate is stretched in advance, and then the core of the electrode plate is roll pressed. . As a result, a highly reliable electrode plate in which the occurrence of a crack or the like is suppressed is manufactured, and by using the electrode plate, a highly reliable secondary battery is realized.

JP, 2014-220113, A

  An object of the present invention is to provide a more reliable electrode plate and a secondary battery using the same.

According to one aspect of the present disclosure, in order to solve the problems described above,
A sheet-like core body comprising a main body portion and a tab portion projecting from the main body portion;
And an active material layer provided on the main body of the core body,
An electrode plate is provided in which a notch is formed at the boundary between the tab portion and the active material layer so as to straddle both the tab portion and the active material layer.

Also, according to another aspect of the present disclosure,
The electrode plate described above,
And a case body for housing the electrode plate.

  According to the present disclosure, a more reliable electrode plate and secondary battery can be provided.

A plan view of a band sheet-like core having an active material layer formed thereon, which is used for an electrode plate according to an embodiment of the present disclosure Sectional view of the core along the line AA of FIG. 1 A plan view of a band sheet-like core body on which a tab portion is formed A plan view of a band sheet-like core body in which a notch portion is formed Diagram showing the compression process of the active material layer The figure which shows the several electrode plate produced by cut | disconnecting a strip sheet-like core body. Enlarged view of the tab part Cross section of secondary battery Figure showing the negative plate A partial enlarged view of an electrode plate according to another embodiment A partial enlarged view of an electrode plate according to another embodiment A partial enlarged view of an electrode plate according to another embodiment A partial enlarged view of an electrode plate according to another embodiment Partially enlarged view of an electrode plate according to different embodiments

  An electrode plate and a secondary battery according to an embodiment of the present disclosure will be described by taking a non-aqueous electrolyte secondary battery as an example. In addition, this indication is not limited to the following forms.

  An electrode plate (for example, a positive electrode plate) used for a secondary battery according to an embodiment of the present disclosure is, for example, manufactured according to the following procedure.

  First, as shown in FIG. 1 and FIG. 2, the active material layer (positive electrode active material layer) 12 is partially formed on both sides of the band sheet-like core 10. 2 is a cross-sectional view taken along the line A-A of FIG. Also, for ease of understanding, an XYZ coordinate system is shown in the drawings.

  Specifically, as shown in FIGS. 1 and 2, the both sides (core exposed portion) 10a in the width direction (Y-axis direction) on both sides of each of the band sheet-like core 10 are left The active material layer 12 is formed in the central portion (active material layer forming portion) 10b. In addition, the cross hatching is given to the active material layer in the top view.

  After the active material layer 12 is formed, the protective layer 14 is partially formed on the active material layer 12 side in the exposed core portion 10a, if necessary. In addition, the dot hatching is given to the protective layer in a top view.

  After the protective layer 14 is formed, as shown in FIG. 3, the core body exposed portion 10 a where the active material layer 12 is not formed is partially cut to form a plurality of tab portions 10 c. The plurality of tab portions 10 c are arranged at intervals in the longitudinal direction (X-axis direction) of the band sheet-like core body 10.

  After the plurality of tab portions 10c are formed, as shown in FIG. 4, through-hole-like notched portions 10d are formed at the boundaries between the plurality of tab portions 10c and the active material layer 12 (the active material layer forming portion 10b). Is formed. In the case of this embodiment, the notch 10 d is formed at the boundary so as to straddle both the tab portion 10 c (specifically, the protective layer 14 on the tab portion) and the active material layer 12. The reason for forming the notch 10d will be described later.

  After the notch portion 10 d is formed, a compression process of compressing the active material layer 12 formed on the core body 10 is performed. For example, as shown in FIG. 5, the core 10 is held by a pair of press rollers RA and RB of a roll press in the thickness direction (Z-axis direction) of the core 10 with a predetermined pressing pressure. By conveying in the longitudinal direction (X-axis direction), the active material layer 12 on the core 10 is compressed. As a result, the packing density of the active material layer 12 is increased.

  After compression of the active material layer 12 is completed, as shown in FIG. 6, the band sheet-like core 10 (active material layer forming portion 10b) is cut at multiple locations in the width direction (Y axis) ( By cutting along the cutting lines CL), a plurality of electrode plates (positive electrode plates) 20 are manufactured. Specifically, an electrode plate having a sheet-like core body 10 including a main body portion 10 e and a tab portion 10 c protruding from the main body portion 10 e, and an active material layer 12 provided on the main body portion 10 e of the core body 10 The (positive electrode plate) 20 is manufactured. That is, the main body portion 10 e of the electrode plate 20 is formed of the rectangular sheet-like core 10 manufactured by dividing the active material layer forming portion 10 b of the band sheet-like core 10 into a plurality. Further, the protective layer 14 covers the root portion of the tab portion 10 c so as to be adjacent to the active material layer 12.

  The reason why the notch 10d is formed at the boundary between the tab portion 10c and the active material layer 12 as shown in FIG. 4 before the compression process of the active material layer 12 will be described below.

  The inventors of the present invention have found that when the pressing pressure (compression pressure) in the pressing process (the compression process of the active material layer) of the core is increased in order to make the packing density of the active material layer higher, It has been found that a crack may occur in the vicinity of the boundary with the active material layer (active material layer forming portion) (that is, the root portion of the tab portion). The inventors also considered forming a notch at the boundary as a countermeasure.

  When pressing the core after forming the tab portion, the core portion (active material layer forming portion) on which the active material layer is formed (the active material layer forming portion) and the tab portion are stretched by different stretching amounts because their thicknesses are different. . Specifically, the tab portion is smaller in thickness than the active material layer forming portion because the active material layer is not formed. Even if the protective layer is formed on the tab portion, the thickness of the protective layer is smaller than the thickness of the active material layer, so the thickness of the tab portion is smaller than the thickness of the active material layer forming portion.

  Due to such a difference in thickness, during the pressing process, a pressing pressure is applied to the active material layer forming portion of the core, and a pressing pressure is hardly applied to the tab portion. As a result, the active material layer-formed portion is stretched at a large stretching amount as compared with the tab portion. A shear stress is generated near the boundary between the active material layer forming portion and the tab portion due to the difference in the amount of stretching, and if the shear stress exceeds the elastic limit, a wrinkle, a curve, or a crack may occur in the vicinity of the boundary.

  However, in practice, wrinkles, curves, or cracks are less likely to occur near the boundary between the active material layer forming portion and the tab portion of the core, and the reason is that between the active material layer forming portion and one tab portion It is considered that the length of the boundary of is short. Moreover, as a reason, since a plurality of tab parts are provided at intervals in the extending direction of the active material layer forming part (conveying direction of the core), distortion may be released at a position where there is no tab part. Conceivable. As a result of these, it is considered that shear stress is less likely to be concentrated to the extent that a crack or the like is generated in the vicinity of the boundary between the active material layer forming portion and the tab portion.

However, during the development of the electrode plate (secondary battery) by the inventors, cracks sometimes occurred in the vicinity of the boundary between the active material layer forming portion and the tab portion of the core. In particular, when the filling density of the active material layer after the pressing process is 3.58 g / cm ³ or more and the width of the tab portion is 10 mm or more, the cracks may be significantly generated. That is, when the compression pressure applied to the active material layer became higher and the length of the boundary between the active material layer-formed portion and the tab portion (ie, the width of the tab portion) became larger, there were cases where cracks occurred remarkably .

  Although the occurrence of cracks in the root portion of the tab portion can be suppressed to some extent by making the width of the tab portion smaller than 10 mm, it is not preferable because the electrical resistance value increases if the width of the tab portion becomes too small.

  Therefore, the inventors formed a notch at the boundary between the tab portion of the core and the active material layer forming portion before the pressing treatment of the core (compression treatment of the active material layer), and It has been found that when pressing is performed after formation, the occurrence of cracks and the like in the vicinity of the boundary between the tab portion and the active material layer forming portion can be effectively suppressed.

  The method for producing the positive electrode plate according to the embodiment of the present disclosure will be described in more detail.

[Fabrication of positive electrode active material layer slurry]
Lithium nickel cobalt manganese complex oxide as positive electrode active material, polyvinylidene fluoride (PVdF) as binder, carbon material as conductive agent, and N-methylpyrrolidone (NMP) as dispersion medium with lithium nickel cobalt manganese complex The mixture is kneaded so that the mass ratio of oxide: PVdF: carbon material is 97.5: 1: 1.5, to prepare a positive electrode active material layer slurry. In addition, it is preferable that the content rate of the positive electrode active material in a positive electrode active material layer sets it as 95 mass% or more, and it is preferable to set it as 99 mass% or less. The content of the binder in the positive electrode active material layer is preferably 0.5% by mass or more, and more preferably 3% by mass or less.

[Preparation of protective layer slurry]
Alumina powder, graphite as a conductive agent, polyvinylidene fluoride (PVdF) as a binder and N-methylpyrrolidone (NMP) as a dispersion medium, and the mass ratio of alumina powder: graphite: PVdF is 83: 3: 14 The slurry is kneaded to make a protective layer slurry. The content of the binder in the protective layer is preferably 5% by mass or more, more preferably 8% by mass or more, and still more preferably 10% by mass or more. The protective layer may be composed only of a binder, but preferably contains ceramic particles such as alumina, zirconia, titania and silica. The protective layer preferably does not contain a positive electrode active material. Even when the protective layer contains a positive electrode active material, the content ratio is preferably 5% by mass or less, and more preferably 1% by mass or less.

[Active Material Layer Forming Step / Protective Layer Forming Step]
The positive electrode active material layer slurry and the protective layer slurry are applied by a die coater on both surfaces of a 15 μm thick aluminum foil as a core for a positive electrode plate. The thickness of the core may be 10 to 20 μm. However, when the core becomes thin, it is assumed that the crack is likely to be generated at the root portion of the tab portion.

  Specifically, the positive electrode active material layer slurry is applied to the central portion (active material layer forming portion) in the width direction of the core body, and the protective layer slurry is applied to each end of the applied positive electrode active material layer slurry in the width direction. It is applied. The positive electrode active material layer slurry and the protective layer slurry may be joined together in the vicinity of the discharge port inside the die head of one die coater, and the positive electrode active material layer slurry and the protective layer slurry may be simultaneously coated on the core.

  The core on which the positive electrode active material layer slurry and the protective layer slurry have been applied is dried, thereby removing the NMP in the slurry. Thereby, the positive electrode active material layer and the protective layer are formed on the core. The thickness of the positive electrode active material layer is larger than the thickness of the protective layer. For example, the thickness of the positive electrode active material layer is 50 to 100 μm, and the thickness of the protective layer is about 5 to 10 μm.

[Tab formation process / notch formation process]
The cutting of the core body to form the tab portion and the notch portion is performed, for example, by irradiating the core body with an energy beam such as a laser. Alternatively, the tab or notch may be formed by press stamping. In addition, a tab part and a notch part may be formed simultaneously, and may be formed in a different timing. Also, the tab portion and the notch portion may be formed by different methods.

[Active material layer compression process]
For example, a strip sheet-like core for a positive electrode plate having a tab portion and a notch portion is conveyed in the longitudinal direction of the core between a pair of press rollers of a roll press and nipped by a predetermined pressing pressure. Ru. Thereby, the active material layer on the core is compressed, and as a result, the packing density of the active material layer is made high. The filling density of the positive electrode active material layer 1 b is preferably 3.58 g / cm ³ or more.

[Parting process]
The core after the step of compressing the active material layer is cut in the width direction at a plurality of locations. Thereby, a plurality of positive electrode plates are completed.

  According to the manufacturing method of such a positive electrode plate, the formation of the notch in the boundary between the tab portion and the active material layer suppresses the generation of a crack in the vicinity of the boundary. The reason why the effect of suppressing the generation of cracks is obtained by the notched portion is presumed as follows.

  The core of the positive electrode plate is stretched by press treatment. However, the amount of extension differs depending on the portion of the core. First, since the active material layer is provided, the active material layer-forming portion of the core having a large thickness is stretched more than the tab portion having a small thickness because the active material layer is not provided, and the tab portion is almost Do not stretch. That is, a large difference in the amount of stretching occurs between the tab portion and the active material layer forming portion.

  Moreover, also in the active material layer forming part of the core, the stretching amount differs depending on the part. Specifically, the amount of extension differs between the portion adjacent to the tab portion and the portion not adjacent to the tab portion. That is, since the portion adjacent to the tab portion is connected to the tab portion which hardly stretches, the stretching is limited, and as a result, the stretching amount is smaller than the portion not adjacent to the tab portion. However, in the active material layer forming portion of the core, since the same pressing pressure is applied to the portion adjacent to the tab portion and the portion not adjacent to the tab portion, the inside of the portion adjacent to the tab portion to which stretching is limited Stress is concentrated.

  Due to the large difference in the amount of stretching between the tab portion and the active material layer forming portion and the concentration of internal stress in the portion adjacent to the tab portion in the active material layer forming portion, the tab portion and the active material layer forming portion Shear stress occurs near the boundary. The shear stress increases as the pressing pressure on the core increases.

  The notch provided at the boundary between the tab portion and the active material layer (active material layer forming portion) serves to reduce the shear force generated in the vicinity of the boundary. That is, due to the notch portion, the length of the boundary between the tab portion and the active material layer forming portion is substantially shortened, whereby the stretching of the portion adjacent to the tab portion in the active material layer forming portion caused by the tab portion Limitations are reduced. As a result, the concentration of internal stress in the portion adjacent to the tab portion is suppressed, and the shear force generated at the boundary between the tab portion and the active material layer can be reduced to such an extent that no crack or the like occurs.

  As shown in FIG. 7, in the positive electrode plate 20, the notch 10d extends in the direction (X-axis direction) of the edge 10f of the main body 10e (the active material layer forming portion 10b) from which the tab 10c protrudes. The shape long in the conveyance direction of the band sheet-like core 10 in a roll press machine is preferable. That is, the notch 10d preferably has a long axis parallel to the boundary between the tab 10c and the active material layer. Thereby, when the opening area of the notch 10d is the same, the tab portion 10c and the active material layer forming portion 10b are compared with the case where the major axis parallel to the projecting direction (Y axis direction) of the tab portion 10c is provided. The boundaries of the above can be made shorter, and as a result, the generation of cracks near the boundaries can be further suppressed in the compression process of the active material layer.

  Moreover, as shown in FIG. 7, in the positive electrode plate 20, the width W1 of the tab portion 10c is preferably 12 mm to 30 mm. During the compression process of the positive electrode plate 20 (core body 10), the smaller the width W1 of the tab portion 10c, the less the crack is generated. However, the smaller the width W1 of the tab portion 10c, the larger the electrical resistance at the tab portion 10c. By providing the notch 10d, it is possible to suppress the occurrence of a crack while suppressing an increase in the electrical resistance.

  Furthermore, the length W2 of the notch 10d (size in the tab portion width direction) is preferably 1/2 to 4/5 of the width W1 of the tab 10c. If the length W2 of the notched portion 10d is too large, the electrical resistance between the tab portion 10c and the main body portion 10e may be too large, and melting may occur between the dove portion 10b and the main body portion 10e. . On the other hand, if the length W2 of the notched portion 10d is too small, the effect of suppressing the above-mentioned crack generation (the effect of reducing the shear force) becomes small, and the tab portion 10c and the main body during the compression process of the active material layer A break may occur between itself and the part 10e. Therefore, it is necessary to select the length W of the notch 10d appropriately.

  Furthermore, it is preferable that only one tab portion 10 c is provided in one positive electrode plate 20. Moreover, in order to use the positive electrode plate 20 for a laminated electrode of a secondary battery, it is preferable that the main body portion 10 e of the positive electrode plate 20 on which the active material layer 12 is formed be flat.

  According to the configuration as described above, the electrode plate (positive electrode plate) can have higher reliability.

  From here, a secondary battery according to an embodiment of the present disclosure, which uses the above-described electrode plate (positive electrode plate), will be described.

[Method of manufacturing secondary battery]
A method of manufacturing a secondary battery (square secondary battery) using the above-described positive electrode plate will be described with reference to FIG. FIG. 8 is a cross-sectional view of a secondary battery according to an embodiment of the present disclosure.

[Fabrication of negative electrode plate]
A negative electrode active material layer slurry containing graphite as a negative electrode active material, styrene butadiene rubber (SBR) as a binder, carboxymethyl cellulose (CMC) as a thickener, and water is prepared. The negative electrode active material layer slurry is partially applied to both surfaces of a rectangular copper foil having a thickness of 8 μm as a core for a negative electrode plate. And by drying this, the water in a negative electrode active material layer slurry is removed, and a negative electrode active material layer is formed on a negative core body. Thereafter, the negative electrode active material layer is subjected to a compression treatment so as to have a predetermined thickness. By partially cutting the core subjected to the compression treatment so as to form the tab portion, as shown in FIG. 9, the core having the main body portion 30a and the tab portion 30b protruding from the main body portion 30a A negative electrode plate 40 including the negative electrode active material layer 30 and the negative electrode active material layer 32 provided on the main body 30a is manufactured.

[Preparation of electrode body]
The plurality of positive electrode plates 20 and the plurality of negative electrode plates 40 prepared by the above-described method are laminated via a polyolefin separator (not shown) to produce a laminated electrode assembly 50 shown in FIG. Each of the positive electrode plate 20 and the negative electrode plate 40 is maintained in a flat state without being bent. The stacked electrode assembly 50 includes a positive electrode tab portion 50a and a negative electrode tab portion 50b protruding from one end thereof. The positive electrode tab portion 50 a is configured by overlapping the tab portions 10 c of the plurality of positive electrode plates 20. The negative electrode tab portion 50 b is configured by overlapping the tab portions 30 b of the plurality of negative electrode plates 40.

  In the laminate type electrode assembly 50, the shape of the separator is not particularly limited. A plurality of flat separators may be used. In addition, a bag-like separator may be used in which one of the positive electrode plate and the negative electrode plate is accommodated. Alternatively, the strip-shaped separator may be folded ninety-nine, and the positive electrode plate and the negative electrode plate may be alternately arranged in a plurality of gaps formed by the ninety-nine fold.

[Assembly of sealing body]
As shown in FIG. 8, the sealing plate 52 of the secondary battery 100 includes a positive electrode terminal attachment hole 52 a and a negative electrode terminal attachment 52 b.

  As shown in FIG. 8, the insulating member 54 and the positive electrode current collector 56 are disposed on the inside of the battery with respect to the sealing plate 52 so as to overlap the positive electrode terminal attachment hole 52 a. Further, the insulating member 58 is disposed on the battery outer side with respect to the sealing plate 52 so as to overlap the positive electrode terminal mounting hole 52a. Then, the positive electrode terminal 60 is inserted from the outside of the battery into the through holes provided in each of the insulating member 58, the insulating member 54, and the positive electrode current collector 56, and the tip of the positive electrode terminal 60 is crimped to the positive electrode current collector 56. It is fixed. The tip of the positive electrode terminal 60 fixed by caulking may be welded to the positive electrode current collector 56.

  Similarly, the insulating member 62 and the negative electrode current collector 64 are disposed on the inner side of the battery with respect to the sealing plate 52 so as to overlap the negative electrode terminal attachment holes 52b. In addition, an insulating member 66 is disposed on the battery exterior side with respect to the sealing plate 52 so as to overlap the negative electrode terminal mounting hole 5b. Then, the negative electrode terminal 68 is inserted from the outside of the battery into the through holes provided in each of the insulating member 66, the insulating member 62, and the negative electrode current collector 64, and the tip of the negative electrode terminal 68 is crimped to the negative electrode current collector 64. It is fixed. The tip of the negative electrode terminal 68 fixed by caulking may be welded to the negative electrode current collector 64.

[Connection of tab part and current collector]
The positive electrode tab portion 50 a of the stacked electrode assembly 50 is welded to the positive electrode current collector 56, and the negative electrode tab portion 50 b is welded to the negative electrode current collector 64. In addition, resistance welding, laser welding, ultrasonic welding etc. can be used as these welding.

[Assembly of secondary battery]
The stacked electrode body 50 covered with the insulating sheet 70 is accommodated in the outer casing 72 having a bottomed rectangular cylindrical shape. Thereafter, by welding between the package body 72 and the sealing plate 52, the opening of the package body 72 is sealed by the sealing plate 52. Thereafter, a non-aqueous electrolytic solution containing an electrolyte and a solvent is injected into the exterior body 72 through the electrolytic solution injection hole 52 c provided in the sealing plate 52. Thereafter, the electrolyte injection hole 52 c is sealed by the sealing plug 74.

  The sealing plate 52 is provided with a gas discharge valve 76 that is broken when the pressure inside the battery exceeds a predetermined value, thereby discharging the gas inside the battery to the outside. Alternatively, a current blocking mechanism may be provided on the conductive path between the positive electrode plate 20 and the positive electrode terminal 60 or the conductive path between the negative electrode plate 40 and the negative electrode terminal 68. Preferably, the current interrupting mechanism operates when the pressure inside the battery exceeds a predetermined value, and cuts the conductive path. In this case, the operating pressure of the current interrupting mechanism is set lower than the operating pressure of the gas discharge valve.

Moreover, as shown in FIG. 9, the notch part is not formed in the negative electrode plate 40 in the above-mentioned secondary battery 100. As shown in FIG. However, in the negative electrode plate 40, as in the positive electrode plate 20, a notch may be formed at the boundary between the tab portion 30b and the main portion 30a where the negative electrode active layer 32 is formed. However, it is particularly effective to apply the notch to the positive electrode plate. In particular, application to a positive electrode plate having a positive electrode active material layer having a packing density of 3.58 g / cm ³ or more after compression treatment is effective.

  By using a more reliable positive electrode plate, the secondary battery can have higher reliability.

  The electrode plate according to the present disclosure and the secondary battery using the electrode plate have been described above by taking the above-described embodiment, but the embodiment according to the present disclosure is not limited to the above-described embodiment.

  For example, in the case of the above-described embodiment, as shown in FIG. 6, the base portion of the tab portion 10 c in the electrode plate (positive electrode plate) 20 is covered by the protective layer 14. For example, in the laminated type electrode body of the secondary battery, this protective layer is useful when there is a possibility that the root portion of the tab portion in the electrode plate in which the notch portion is formed contacts the separator. That is, it is useful that the notch is formed to extend over both the protective layer and the active material layer on the tab portion. If there is such a possibility, if there is no protective layer, the edge of the notch on the tab side, that is, the sharp edge of the core made of metal penetrates the separator, and the other side across the separator is opposed There is a risk of contact with electrode plates of different polarity. This possibility is reduced by the protective layer covering the edge of the notch. In addition, the protective layer suppresses the occurrence of cracks at the end of the notch where stress is likely to be concentrated. The protective layer can be omitted if there is little possibility that the edge of the notch penetrates the separator or the possibility of cracking at the end of the notch.

  Moreover, various forms are possible for the notch part formed in an electrode plate. 10 to 13 are partially enlarged views of an electrode plate according to another embodiment, showing various forms of notches. In addition, the electrode plate shown to FIGS. 10-13 is the structure same as the above-mentioned embodiment except the form of a notch part.

  Unlike the rectangular notch 10d in the electrode plate 20 according to the above-described embodiment shown in FIG. 7, in the electrode plate 220 shown in FIG. 10, the notch 210d has a triangular shape. Specifically, it has a triangular shape in which the apex is in the tab portion 10c and the bottom is in the active material layer 12 (the main portion 10e).

  When the triangular base side length is the same as the length W2 of the notch 10d in the above-described embodiment shown in FIG. 7, the notch 210d of the electrode plate 220 is cracked or the like in the same manner as the notch 10d. It is possible to suppress the occurrence of the electric resistance between the tab portion 10c and the main body portion 10e (the increase caused by the formation of the notch portion) as compared with the notch portion 10d. it can. That is, compared with the case of the rectangular notch 10d, in the case of the triangular notch 210d, since the boundary length (connection length) between the tab 10c and the main body 10e is large, the electric resistance is increased. small. In order to reduce the electrical resistance, that is, to increase the connection length, the height of the triangular shape of the notch 210d is preferably smaller than the base length.

  In the electrode plate 320 shown in FIG. 11, the notches 310 d are a plurality of circular holes arranged side by side on the boundary between the tab portion 10 c and the active material layer 12 (main body portion 10 e). The number of circular holes is preferably 4 or more, and the diameter size of the circular holes is preferably 1/4 or less of the length W2 of the notch 10d in the above-described embodiment. Thereby, while being able to suppress generation | occurrence | production of a crack etc. to substantially the same extent as the notch 10d of embodiment shown in FIG. 7, compared with the notch 10d, between the tab part 10c and the main-body part 10e. An increase in electrical resistance can be suppressed.

  In the electrode plate 420 shown in FIG. 12, the end of the notch portion 410d has an arc shape. Because of the arc shape, stress is less likely to be concentrated at the end of the notch portion 410 d. As a result, the occurrence of cracks at the end of the notch is suppressed.

  In the electrode plate 520 shown in FIG. 13, both ends of the notch portion 510 d are V-shaped. Specifically, it has a V-shape in which the middle point is in the tab portion 10c and the both ends are in the active material layer 12 (the main portion 10e). In this case, as with the triangular notch 210d shown in FIG. 10, it is possible to suppress the occurrence of a crack or the like and the increase in electrical resistance. Further, in the case of the V shape, the amount of the active material cut by the formation of the notch portion is smaller than in the case of the triangle shape.

  Furthermore, as in the electrode plate 620 according to a different embodiment shown in FIG. 14, the corner 10 g formed between the tab 10 c and the main body 10 e may be a rounded corner. The R-shaped corner portion suppresses generation of shear force (stress concentration) in the vicinity of the boundary between the tab portion 10c and the main body portion 10e. The corner portion between the tab portion 10c and the main portion 10e in the electrode plate 20, 220, 320, 420, 520 in the form shown in FIGS. 7 and 10 to 13 may also be an R-shaped corner portion. .

  Furthermore, in the case of the above-mentioned embodiment, although the notch formed in an electrode plate is a penetration hole which penetrates a core, it may be a notch-like notch.

  Furthermore, the core in the electrode plate according to the embodiment of the present disclosure may be a non-porous metal foil and is preferable. In particular, the core for the positive electrode plate is preferably an aluminum foil or an aluminum alloy foil. The core for the negative electrode plate is preferably a copper foil or a copper metal foil.

  The positive electrode active material used for the electrode plate as the positive electrode plate according to the embodiment of the present disclosure is preferably a lithium transition metal composite oxide. In particular, lithium transition metal complex oxides containing at least one of nickel, cobalt and manganese are preferred.

  The negative electrode active material used for the electrode plate as the negative electrode plate according to the embodiment of the present disclosure may be a material capable of absorbing and releasing lithium ions. Examples of materials capable of absorbing and desorbing lithium ions include carbon materials such as graphite, non-graphitic carbon, graphitizable carbon, fibrous carbon, coke, and carbon black. Examples of non-carbon-based materials include silicon, tin, and alloys or oxides mainly containing them. A carbon material and a non-carbon material may be mixed.

  As a binder contained in the active material layer and the protective layer of the electrode plate, polyvinylidene fluoride (PVDF), polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamidoimide, polyacrylonitrile, polyacrylic acid , Poly (methyl acrylate), poly (ethyl acrylate), poly (hexyl acrylate), poly (methacrylic acid), poly (methyl methacrylate), poly (ethyl methacrylate), poly (hexyl methacrylate), poly (vinyl acetate), polyvinyl pyrrolidone, polyether, polyether sulfone, Hexafluoropolypropylene, styrene butadiene rubber, carboxymethyl cellulose, acrylic rubber, acrylate binder (ester or salt of acrylic acid) or the like can be used. These may be used alone or in combination of two or more. The binder contained in the active material layer and the binder contained in the protective layer may be the same or different. The binder is preferably made of resin.

  It is preferable to set it as 5 mass% or more, and, as for the mass ratio with respect to the protective layer of the binder contained in a protective layer, it is more preferable to set it as 10 mass% or more. It is preferable that the mass ratio with respect to the protective layer of the binder contained in a protective layer is 95 mass% or less. However, the protective layer may be composed of only the binder. However, the protective layer preferably contains at least one of alumina, zirconia, titania and silica as ceramic particles.

Moreover, in the present specification, a method of manufacturing an electrode plate of a secondary battery is also disclosed. Specifically,
A method of manufacturing an electrode plate for a secondary battery, comprising: a sheet-like core body having a main body portion and a tab portion projecting from the main body portion; and an active material layer provided on the main body portion of the core body ,
Forming the active material layer on the core body;
A notch is formed at the boundary between the tab portion and the active material layer so as to straddle both the tab portion and the active material layer,
The manufacturing method of the electrode plate which compresses the active material layer on the core body in which the said notch part was formed is disclosed.

  According to such a method for manufacturing an electrode plate for a secondary battery, generation of cracks or the like at the root of the tab portion during compression of the active material layer is suppressed by the notch portion. As a result, a more reliable electrode plate can be manufactured. Also, a secondary battery using such an electrode plate can have higher reliability.

  As described above, the embodiment has been described as an illustration of the technology in the present disclosure. For that purpose, the attached drawings and the detailed description are provided. Therefore, among the components described in the attached drawings and the detailed description, not only components that are essential for solving the problem but also components that are not essential for solving the problem in order to exemplify the above-mentioned technology. Elements may also be included. Therefore, the fact that those non-essential components are described in the attached drawings and the detailed description should not immediately mean that those non-essential components are essential.

  Moreover, since the above-mentioned embodiment is for illustrating the technique in this indication, various change, substitution, addition, omission, etc. can be performed within the range of a claim or its equivalent.

  For example, the embodiment of the present disclosure is applicable not only to the electrode plate used for the stacked electrode assembly, but also to the electrode plate used for the wound electrode assembly.

10 core body 10c tab portion 10d notch portion 10e main body portion 12 active material layer

Claims (11)

A sheet-like core body comprising a main body portion and a tab portion projecting from the main body portion;
And an active material layer provided on the main body of the core body,
An electrode plate, wherein a notch is formed at the boundary between the tab portion and the active material layer so as to straddle both the tab portion and the active material layer.   The electrode plate according to claim 1, wherein the notch portion is a through hole penetrating the core body. The core is an aluminum foil or an aluminum alloy foil,
The electrode plate according to claim 1, wherein a packing density of the active material layer is 3.58 g / cm ³ or more.   The electrode plate according to any one of claims 1 to 3, wherein the notch has a long axis parallel to a boundary between the tab portion and the active material layer.   The electrode plate according to any one of claims 1 to 4, wherein the size of the notch portion is 1/2 to 4/5 of the size of the tab portion with respect to the size of the tab portion in the width direction. The base portion of the tab portion is covered to be adjacent to the active material layer, and a protective layer including ceramic particles and a binder is further provided,
The electrode plate according to any one of claims 1 to 5, wherein the notch portion is formed so as to extend over both the protective layer on the tab portion and the active material layer.   The electrode plate according to any one of claims 1 to 6, wherein the notch portion has a triangular shape with an apex at the tab portion and a base at the active material layer.   The electrode plate according to any one of claims 1 to 7, wherein an end of the notch is arc-shaped.   The electrode plate according to any one of claims 1 to 8, wherein a corner portion formed between the tab portion and the main body portion is a rounded corner portion. The electrode plate according to any one of claims 1 to 9,
And a case body for housing the electrode plate.   The secondary battery according to claim 10, wherein the electrode plate is an electrode plate for a positive electrode.

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