JP2014116080A - Electricity storage device and method for manufacturing electricity storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electricity storage device increasing adhesion with a metal foil at a marginal part of an active material layer, thereby capable of hardly causing separation of the active material layer from the metal foil, and a method for manufacturing an electricity storage device.SOLUTION: In a positive electrode sheet 18, a positive electrode boundary portion 18c where is the marginal part of a positive electrode active material layer 22 has an inclined face 30 inclined toward the direction vertical to a surface 21a of a positive electrode metal foil 21, and the inclination angle θ of the inclined face 30 is 5° or above and 45° or below.

Description

  The present invention relates to a power storage device and a method for manufacturing the power storage device.

  Conventionally, lithium ion secondary batteries, nickel-hydrogen secondary batteries, and the like are well known as power storage devices mounted on vehicles such as EVs (Electric Vehicles) and PHVs (Plug-in Hybrid Vehicles). Some of these power storage devices have an electrode assembly in which electrodes (a positive electrode and a negative electrode) having an active material layer on the surface of a metal foil overlap each other with a separator interposed therebetween (for example, Patent Document 1).

  In the power storage device of Patent Document 1, the active material layer is intermittently formed on the belt-shaped metal foil, and the density of the edge of the adjacent active material layer with the non-formed portion where the active material layer is not formed being sandwiched, It is higher than the density of other parts. For this reason, in patent document 1, the intensity | strength in the edge part of an active material layer is improved, and it suppresses that an active material layer falls off from metal foil.

JP 2003-208890 A

  However, in Patent Document 1, since the inclination angle of the edge of the active material layer with respect to the surface of the metal foil is large, when the roll is pressed from the edge, the press roll comes into contact with the edge of the active material layer. Due to this reaction, the metal foil moves in a direction away from the surface of the metal foil, and there is a possibility that the edge of the active material layer cannot be sufficiently pressurized. When the edge of the active material layer cannot be sufficiently pressurized, the adhesion between the active material layer and the metal foil is lowered, and the active material layer may be easily peeled off from the metal foil.

  This invention was made paying attention to the problem which exists in the said prior art, and the objective is to improve the adhesiveness with the metal foil in the edge of an active material layer, and to peel an active material layer from a metal foil It is an object of the present invention to provide a power storage device and a method for manufacturing the power storage device that are difficult to perform.

  A power storage device that solves the above-described problem has a plurality of electrodes in which an active material layer is formed on at least one surface of a metal foil, and a separator that insulates between the plurality of electrodes. A power storage device having a stacked electrode assembly that overlaps in a layered manner with a gap interposed therebetween, and at least part of an edge of the active material layer is inclined with respect to a direction perpendicular to the surface of the metal foil It has an inclined surface, and the gist of the inclined angle of the inclined surface is 5 ° or more and 45 ° or less.

  According to this, at least a part of the edge of the active material layer has an inclined surface that is inclined with respect to a direction perpendicular to the surface of the metal foil, and the inclination angle of the inclined surface is 5 ° or more and 45 °. ° or less. For this reason, by roll-pressing from the edge portion where the inclined surface is formed, it is suppressed that the press roll moves away from the surface of the metal foil due to the reaction when the press roll comes into contact with the edge portion of the active material layer. Thus, the edge of the active material layer can be sufficiently pressurized. Therefore, the adhesiveness with the metal foil in the edge part of an active material layer can be improved, and an active material layer can be made hard to peel from metal foil.

  In the power storage device, the outer shape of the metal foil and the active material layer is a rectangle, and the electrode is exposed along at least one edge of the edge of the metal foil. It is preferable that the inclined surface is provided on at least a part of the edge of the active material layer on the metal foil exposed portion side.

  According to this, since the inclined surface is provided on at least a part of the edge part on the metal foil exposed part side of the edge part of the active material layer, roll pressing is performed from the edge part on the metal foil exposed part side. Thus, particularly at the boundary portion between the exposed portion of the metal foil and the edge portion of the active material layer, the adhesion between the active material layer and the metal foil can be increased and the separation can be made difficult.

  In the power storage device, the metal foil and the active material layer have a rectangular outer shape, and the inclined surface is provided over at least one of the edges of the active material layer. It is preferable. According to this, it is possible to improve the adhesion between the active material layer and the metal foil over the entire edge where the inclined surface is provided, and to make it difficult to peel off.

In the power storage device, it is preferable that an edge portion having the inclined surface of the edge portion of the active material layer has a wave shape when viewed from a direction perpendicular to the surface of the metal foil.
According to this, since the edge part which has an inclined surface is a waveform, compared with the case where an edge part is formed linearly, the full length of an edge part is lengthened, and the edge part of an active material layer is made more metal. It can be made difficult to peel from the foil.

Moreover, about the said electrical storage apparatus, it is preferable that the edge part which has a metal foil exposed part which this metal foil exposes among the edge parts of the said metal foil has a tab part to which an external terminal is electrically connected.
According to this, when the electrode assembly repeatedly expands and contracts in the electrode stacking direction due to charge and discharge, the relative position of the external terminal and the electrode fluctuates, which causes a load on the tab portion. Even so, since the adhesion at the edge of the active material layer located on the tab portion side is improved, the active material layer can be prevented from peeling from the metal foil.

  In the power storage device, the power storage device is preferably a secondary battery. According to this, as a secondary battery, the adhesiveness with the metal foil at the edge of the active material layer can be improved, and the active material layer can be hardly separated from the metal foil.

  In addition, in the method for manufacturing a power storage device that solves the above-described problem, at least a part of an edge of the active material mixture containing an active material on the surface of the metal foil with respect to a direction perpendicular to the surface of the metal foil Including a forming step of forming the inclined surface inclined at an angle of 5 ° or more and 45 ° or less, and a pressing step of compressing the active material mixture by roll pressing from an edge portion where the inclined surface is formed. Is the gist.

  According to this, in the forming step, at least part of the edge of the active material mixture on the surface of the metal foil is inclined at an angle of 5 ° to 45 ° with respect to the direction perpendicular to the surface of the metal foil. A surface is formed, and in the pressing step, roll pressing is performed from an edge portion where the inclined surface is formed. Therefore, it is suppressed that the press roll moves in a direction away from the surface of the metal foil due to the reaction when the press roll comes into contact with the edge of the active material mixture, and thereby the edge of the active material mixture (active material layer) is prevented. Fully pressurized. Therefore, the adhesiveness with the metal foil in the edge part of an active material layer can be improved, and an active material layer can be made hard to peel from metal foil.

  ADVANTAGE OF THE INVENTION According to this invention, adhesiveness with the metal foil in the edge part of an active material layer can be improved, and an active material layer can be made hard to peel from metal foil.

Sectional drawing which shows a lithium ion secondary battery typically. The perspective view which shows an electrode assembly typically. FIG. 3 is a cross-sectional view taken along line 1-1 shown in FIG. 2. The front view which shows typically the manufacturing apparatus of a lithium ion secondary battery. The top view which shows typically a part of manufacturing apparatus of a lithium ion secondary battery. 2-2 sectional drawing shown in FIG. The front view which expands and schematically shows a part of manufacturing apparatus of a lithium ion secondary battery. The front view which shows typically the positive electrode sheet in another embodiment. The front view which shows typically the positive electrode sheet in another embodiment. The front view which shows typically the inclined surface in another embodiment. The front view which shows typically the inclined surface in another embodiment.

Hereinafter, an embodiment of the power storage device will be described.
As shown in FIG. 1, for example, a lithium ion secondary battery (hereinafter referred to as “secondary battery”) 10 as a power storage device mounted on a vehicle such as a passenger vehicle or an industrial vehicle includes a case 11 and an electrode assembly 12. Contained.

  The case 11 includes a bottomed rectangular box-shaped main body member 11a that houses the electrode assembly 12, and a rectangular plate-shaped lid member 11b that closes an opening of the main body member 11a. The main body member 11a and the lid member 11b are made of a metal such as stainless steel or aluminum.

  The case 11 is filled with a nonaqueous electrolytic solution 13 as an electrolyte. A positive electrode terminal 15 and a negative electrode terminal 16 as external terminals protrude from the lid member 11b toward the outside. The electrode assembly 12 is housed in the case 11 in a state of being covered with an insulating resin sheet 14.

  As shown in FIG. 2, the electrode assembly 12 includes a positive electrode sheet 18 as an electrode (first electrode, positive electrode) and a negative electrode sheet 19 as an electrode (second electrode, negative electrode) having a polarity different from that of the positive electrode sheet 18. And a rectangular sheet-like separator 20 that insulates between the positive electrode sheet 18 and the negative electrode sheet 19. The electrode assembly 12 is a stacked electrode assembly in which a plurality of positive electrode sheets 18 and a plurality of negative electrode sheets 19 are alternately stacked with separators 20 interposed therebetween, and these are stacked in layers. . In the following description, the “stacking direction” means the stacking direction of the positive electrode sheet 18 and the negative electrode sheet 19 in the electrode assembly 12.

  As shown in FIG. 2, the positive electrode sheet 18 includes a positive electrode metal foil (aluminum foil in the present embodiment) 21 whose outer shape is rectangular, and a positive electrode active material and a conductive agent on both surfaces of the positive electrode metal foil 21. And a positive electrode active material layer 22 coated with an active material mixture containing a binder and dried.

  In addition, the positive electrode active material layer 22 has a constant width from the second positive electrode edge portion 18b opposite to the first positive electrode edge portion 18a on both sides of the positive electrode metal foil 21, and the first positive electrode edge portion 18a extends in the direction. Is provided over the entire width. Further, on both surfaces of the positive electrode metal foil 21, the positive electrode active material layer 22 is not formed over the entire width in the direction in which the first positive electrode edge 18a extends with a constant width from the first positive electrode edge 18a. A certain positive electrode non-formation part 23 is provided. In the present embodiment, the positive electrode non-forming portion 23 extends along the first positive electrode edge 18 a of the positive metal foil 21 and becomes a metal foil exposed portion (non-forming portion) where the positive metal foil 21 is exposed.

  For this reason, a positive electrode boundary portion 18 c that is a boundary between the positive electrode active material layer 22 and the positive electrode non-forming portion 23 is provided between the first positive electrode edge portion 18 a and the second positive electrode edge portion 18 b. The positive electrode boundary portion 18 c becomes an edge portion on the positive electrode non-forming portion 23 side in the edge portion of the positive electrode active material layer 22. The positive electrode active material layer 22 has a rectangular (substantially rectangular) outer shape.

  A positive electrode current collecting tab 24 as a tab portion protrudes from the first positive electrode edge 18 a of the positive electrode sheet 18. The positive electrode current collecting tab 24 is a part of the positive electrode metal foil 21 constituting the positive electrode non-forming part 23. The positive electrode current collecting tab 24 is formed in the same position and in the same shape in each positive electrode sheet 18 constituting the electrode assembly 12.

  Therefore, as shown in FIG. 1, a positive electrode current collecting tab group 24 a in which a plurality of positive electrode current collecting tabs 24 are stacked in a layered manner is projected from the edge portion 12 a of the electrode assembly 12. A positive electrode terminal 15 is electrically connected to the positive electrode current collecting tab group 24a by welding or the like in a state where a plurality of positive current collecting tabs 24 are gathered in the stacking direction.

  As shown in FIG. 2, the negative electrode sheet 19 includes a negative electrode metal foil (copper foil in this embodiment) 25 whose outer shape is rectangular, and a negative electrode active material, a conductive agent, and An active material mixture containing a binder is applied and the negative electrode active material layer 26 is dried. The negative electrode active material layer 26 is provided across the entire width in the direction in which the first negative electrode edge 19a extends from the first negative electrode edge 19a to the opposite second negative electrode edge 19b on both sides of the negative electrode metal foil 25. ing.

  A negative electrode non-formation portion 27, which is a portion where the negative electrode active material layer 26 is not formed, protrudes from the first negative electrode edge 19 a of the negative electrode metal foil 25 as a negative electrode current collecting tab 28. In the present embodiment, the negative electrode non-forming portion 27 extends along the first negative electrode edge portion 19a of the negative electrode metal foil 25 and becomes a metal foil exposed portion (non-forming portion) where the negative electrode metal foil 25 is exposed. Therefore, a negative electrode boundary portion 19 c that is a boundary between the negative electrode active material layer 26 and the negative electrode non-forming portion 27 is provided at the base end portion of the negative electrode current collecting tab 28. The negative electrode boundary portion 19 c becomes an edge portion on the negative electrode non-forming portion 27 side in the edge portion of the negative electrode active material layer 26. Further, the negative electrode active material layer 26 has a rectangular (substantially rectangular) outer shape.

  As shown in FIG. 1, the negative electrode current collecting tab 28 as a tab portion is formed in the same position and in the same shape in each negative electrode sheet 19 constituting the electrode assembly 12. The negative electrode current collecting tab 28 is provided at a position that does not overlap the positive electrode current collecting tab 24 when the positive electrode sheet 18 and the negative electrode sheet 19 are laminated. Therefore, in one edge portion 12a of the edge portions of the electrode assembly 12, a negative electrode current collecting tab group 28a in which a plurality of negative electrode current collecting tabs 28 are layered in a portion different from the positive electrode current collecting tab group 24a. Is protruding. The negative electrode current collecting tab group 28a is electrically connected to the negative electrode terminal 16 by welding or the like in a state where a plurality of negative electrode current collecting tabs 28 are gathered in the stacking direction.

  As shown in FIG. 2, the positive electrode boundary portion 18 c of the positive electrode sheet 18 has a corrugated shape that extends along the direction in which the positive electrode non-forming portion 23 extends when viewed from the stacking direction. That is, the boundary line between the positive electrode boundary portion 18c and the non-positive electrode forming portion 23 includes a region protruding toward the protruding direction side of the positive electrode current collecting tab 24 and a protruding direction of the positive electrode current collecting tab 24 when viewed from the stacking direction. Regions protruding to the opposite side appear alternately. Similarly, the negative electrode boundary portion 19 c of the negative electrode sheet 19 has a wave shape that extends along the direction in which the negative electrode non-forming portion 27 extends when viewed from the stacking direction.

  In addition, as shown in FIG. 3, in the positive electrode sheet 18, each positive electrode boundary portion 18 c located on the front surface and the back surface of the positive electrode sheet 18 is inclined with respect to a direction perpendicular to the front surface 21 a of the positive electrode metal foil 21. Inclined surfaces 30 are provided in which the thickness of the positive electrode active material layer 22 gradually increases as the distance from the positive electrode non-forming portion 23 that is the exposed metal foil portion increases. The inclined surface 30 has an inclination angle θ with respect to the surface 21a of preferably 5 ° to 45 °. The inclined surface 30 is provided over the entire positive electrode boundary portion 18c.

  In the present embodiment, the negative electrode boundary portion 19 c of the negative electrode sheet 19 is also provided with the inclined surface 30 in the same manner as the positive electrode sheet 18. In addition, since the inclined surface 30 in the positive electrode sheet 18 and the inclined surface 30 in the negative electrode sheet 19 are the same structures, the detailed description is abbreviate | omitted.

Next, the manufacturing apparatus 40 of the secondary battery 10 will be described.
As shown in FIG. 4, when manufacturing the positive electrode sheet 18, the manufacturing apparatus 40 is an apparatus for providing the positive electrode active material layer 22 on the coating surface M <b> 1 that is one side of the positive electrode metal foil 21. When manufacturing, it is an apparatus for providing the negative electrode active material layer 26 on the coating surface M1 which is one side of the negative electrode metal foil 25.

  The manufacturing apparatus 40 includes a supply mechanism 31 for setting and supplying the strip-shaped metal foils 21 and 25 wound in a roll shape on the supply roll 31a. A transfer device 33 that transfers (applies) an active material paste 32 as an active material mixture to the supplied metal foils 21 and 25 downstream of the supply mechanism 31 in the transport direction Y1 of the metal foils 21 and 25. Is provided. Instead of the transfer device 33, the active material mixture may be applied by die coating.

  The transfer device 33 has a tank 33 a for storing the active material paste 32. As the active material paste 32 transferred to the positive electrode metal foil 21, a material in which a positive electrode active material, a conductive agent, a binder, and a solvent are kneaded is used. Moreover, as the active material paste 32 transferred to the negative electrode metal foil 25, a mixture of a negative electrode active material, a conductive agent, a binder, and a solvent is used.

  Further, the transfer device 33 is rotatably supported in the direction Y2 opposite to the transport direction Y1 around the axis, and the cylindrical coating roll to which the active material paste 32 supplied from the tank 33a is attached to the outer peripheral surface. 33b. In addition, in the transfer device 33, the active material paste 32 is formed on the surface of the coating roll 33b with such a width that non-application portions where the active material paste 32 is not transferred are formed on both edges in the width direction of the metal foils 21 and 25. It comes to be attached.

  The transfer device 33 is arranged parallel to and spaced from the coating roll 33b, and the thickness of the active material paste 32 attached to the coating roll 33b according to the distance from the coating roll 33b in the gap between the transfer roll 33b. It has a substantially cylindrical comma roll 33c that regulates the thickness.

  Further, the transfer device 33 has a cylindrical backing roll 33d that is rotatably supported around the axis in the transport direction Y1 and transports the metal foils 21 and 25 in the transport direction Y1. The backing roll 33d can be positioned at a transfer position where the metal foils 21 and 25 are brought close to the coating roll 33b and the active material paste 32 is transferred to the application surface M1 of the metal foils 21 and 25. Further, the backing roll 33d is a position away from the transfer position, and the metal foils 21 and 25 are not brought close to the coating roll 33b, and are separated from the application surface M1 of the metal foils 21 and 25 so that the active material paste 32 is not transferred. Position is possible. The backing roll 33d is movable between a transfer position and a separation position.

  The manufacturing apparatus 40 is provided with a control device 39 connected to the backing roll 33d and capable of controlling the position and rotation speed of the backing roll 33d. The control device 39 repeatedly moves the backing roll 33d between the transfer position and the separation position.

  Further, a drying furnace 34 for drying the active material paste 32 transferred to the coating surface M1 of the metal foils 21 and 25 is provided downstream of the transfer device 33 in the transport direction Y1. Inside the drying furnace 34, a high-temperature heat medium (for example, gas such as air or nitrogen gas) is supplied from the outside to heat the active material paste 32 transferred to the metal foils 21 and 25, and at the same time, the active material paste 32. The solvent vapor evaporated from the inside is removed from the drying furnace 34.

  A roll press (compression) is performed downstream of the outlet of the drying furnace 34 in the transport direction Y1 while the metal foils 21 and 25 are transported in the transport direction Y1 and the dried active material paste 32 is heated by a pair of press rolls 38a. A press mechanism 38 is provided.

  Each press roll 38a has a shock relaxation mechanism (not shown) such as a spring. When an impact in a direction perpendicular to the coating surface M1 is applied to each press roll 38a from the metal foil 21 or 25 side, the metal foil 21 is provided. , 25 to move slightly away from each other so as to alleviate the impact. Further, the manufacturing apparatus 40 includes a winding roll 38b that winds the metal foils 21 and 25 downstream of the press roll 38a in the transport direction Y1 of the metal foils 21 and 25.

Next, a method for manufacturing the secondary battery 10 will be described together with its operation.
As shown in FIG. 4, the metal foils 21 and 25 wound in a roll shape are set on a supply roll 31a, and the prepared active material paste 32 is put into a tank 33a. In addition, the active material paste 32 is attached to the surface of the coating roll 33b with such a width that non-application portions are formed at both edges in the width direction of the metal foils 21 and 25.

  Subsequently, while the backing roll 33d is rotated in the transport direction Y1 by the control device 39, it is moved at a predetermined time interval between the transfer position and the separation position, and the active material paste 32 is applied to the coating surface M1 of the metal foils 21 and 25. Are transferred (applied) intermittently and in a substantially rectangular shape (transfer (applying) step).

  As a result, as shown in FIGS. 5 and 6, a substantially rectangular application part 32 a to which the active material paste 32 is applied is applied to the application surface M <b> 1 of the metal foils 21 and 25 along the transport direction Y <b> 1. The non-application part 32b where the substance paste 32 is not applied is formed so as to be adjacent to each other with the non-application part 32b interposed therebetween.

  In the transfer process of the present embodiment, the metal foils 21 and 25 are formed over the entire edge 32c formed on the side of the metal foils 21 and 25 in the transport direction Y1 among the edges of the active material paste 32 in the application part 32a. An inclined surface 30 that is inclined at an angle of 5 ° or more and 45 ° or less with respect to a direction perpendicular to the coating surface M1 is formed. That is, the transfer process of the present embodiment is also a forming process for forming the inclined surface 30.

  The inclined surface 30 of the edge portion 32c in the active material paste 32 is 1 of the rotational speed of the backing roll 33d in the transfer process, the moving speed of the backing roll 33d, and the thickness of the active material paste 32 attached to the coating roll 33b by the comma roll 33c. It can be formed by adjusting one or more. That is, in the transfer step, the active material paste 32 is transferred from the thin film thickness to the coated surface M1 of the metal foils 21 and 25, and gradually transferred from the thin film thickness to the inclined surface. 30 is formed.

  For example, by reducing the speed when the backing roll 33d moves to the transfer position, the thickness of the active material paste 32 attached to the metal foils 21 and 25 is gradually increased, and the inclined surface 30 is formed. it can. Further, for example, when the coating roll 33b moves to the transfer position, the rotation speed of the backing roll 33d is gradually decreased from a state where the rotation speed is faster than usual when reaching the transfer position, whereby the metal foil 21 is moved. , 25, the inclined surface 30 can be formed by gradually increasing the film thickness of the active material paste 32 attached thereto.

  Moreover, the inclined surface 30 can be formed by gradually increasing the film thickness of the active material paste 32 attached to the coating roll 33b by the comma roll 33c. The inclined surface 30 can also be formed by adjusting the viscosity of the active material paste 32 to an appropriate viscosity.

  Further, in the transfer process, the active material paste 32 is transferred from a thin film thickness to a gradually thick film thickness with respect to the application surface M1 of the metal foils 21 and 25, so that the metal foils 21 and 25 are slightly bent. Further, sagging occurs in the active material paste 32 due to unevenness, and the entire edge portion 32c is formed in a corrugated shape. In the present embodiment, the edge of the active material paste 32 opposite to the edge 32c is also formed in a corrugated shape, and the inclined surface 30 is provided.

  Next, the active material paste 32 is dried in the drying furnace 34. The active material paste 32 is solidified while maintaining the state in which the inclined surface 30 is formed on the edge portion 32c. Then, while transporting the metal foils 21 and 25 in the transport direction Y1, the dried active material paste 32 is roll-pressed and compressed while being heated by a pair of press rolls 38a (press process). The active material layers 22 and 26 are completed by this pressing process.

  At this time, as shown in FIG. 7, in the press mechanism unit 38, the metal foils 21 and 25 are transported in the transport direction Y1, whereby the active material paste 32 is roll-pressed from the edge 32c where the inclined surface 30 is formed. And compress. For this reason, the press roll 38a roll-presses while gently riding on the solidified active material paste 32 along the inclined surface 30 having the inclination angle θ of 5 ° or more and 45 ° or less (indicated by an arrow Y3).

  Here, when the inclination angle θ of the inclined surface 30 is less than 5 °, there are many portions where the active material layers 22 and 26 are thin, and the electric capacity of the secondary battery 10 may be reduced. . On the other hand, when the inclination angle θ exceeds 45 °, the press roll 38a moves in a direction away from the surfaces of the metal foils 21 and 25 due to the reaction when contacting the solidified active material paste 32, and the edge portion 32c. In this case, the active material paste 32 cannot be sufficiently pressed.

  Next, as shown in FIG. 4, the metal foils 21 and 25 are wound up by the winding roll 38b. The wound metal foils 21 and 25 are set again on the supply roll 31a of the manufacturing apparatus 40, and the surface on which the active material layers 22 and 26 are not formed is used as a new application surface M1 in the same manner as described above. Layers 22 and 26 are formed. Note that the active material layers 22 and 26 are formed at positions where they overlap on both surfaces of the metal foils 21 and 25.

  Then, as shown in FIG. 5, the positive electrode metal foil 21 having the positive electrode active material layer 22 formed on both sides is punched out so that the positive electrode current collecting tab 24 is located on the edge 32c side of the active material paste 32, and the positive electrode The sheet 18 is completed. That is, the edge part 32 c of the active material paste 32 becomes the positive electrode boundary part 18 c in the positive electrode sheet 18, and the non-application part 32 b becomes the positive electrode non-formation part 23.

  Similarly, the negative electrode metal foil 25 having the negative electrode active material layer 26 formed on both sides is punched out so that the negative electrode current collecting tab 28 is positioned on the edge 32c side of the active material paste 32, and the negative electrode sheet 19 is completed. Is done. That is, the edge part 32 c of the active material paste 32 becomes the negative electrode boundary part 19 c in the negative electrode sheet 19, and the non-application part 32 b becomes the negative electrode non-formation part 27.

  Next, the positive electrode sheets 18 and the negative electrode sheets 19 are alternately stacked with the separators 20 interposed therebetween to form the electrode assembly 12. Next, the electrode assembly 12 covered with the resin sheet 14 is accommodated in the case 11, the positive current collecting tab group 24 a and the positive terminal 15 are electrically connected, and the negative current collecting tab group 28 a and the negative terminal 16 are connected. And electrically connect. Then, the non-aqueous electrolyte 13 is injected into the case 11 to complete the secondary battery 10.

Therefore, according to the present embodiment, the following effects can be obtained.
(1) The positive electrode boundary portion 18 c has an inclined surface 30 that is inclined in a range of 5 ° to 45 ° with respect to a direction perpendicular to the surface 21 a of the positive electrode metal foil 21. Therefore, when the press roll 38a comes into contact with the edge portion 32c of the active material paste 32 (the positive electrode boundary portion 18c of the positive electrode active material layer 22) by performing roll press from the edge portion where the inclined surface 30 is formed. The movement due to the reaction is suppressed, whereby the edge portion 32c can be sufficiently pressurized. Therefore, the adhesiveness with the positive electrode metal foil 21 in the positive electrode boundary part 18c of the positive electrode active material layer 22 can be improved, and the positive electrode active material layer 22 can be hardly separated from the positive electrode metal foil 21. Such an effect is the same for the negative electrode sheet 19.

  (2) Since the inclined surface 30 is provided at the positive electrode boundary portion 18c on the positive electrode non-forming part 23 side, roll pressing from the positive electrode non-forming part 23 side, in particular, the positive electrode non-forming part 23 and the positive electrode active material Adhesion between the positive electrode active material layer 22 and the positive electrode metal foil 21 can be improved at the boundary portion between the layer 22 and the positive electrode boundary portion 18c, and the layer 22 can hardly be peeled off. Such an effect is the same for the negative electrode sheet 19.

  (3) The inclined surface 30 is provided over the entire positive electrode boundary portion 18c. For this reason, adhesiveness with the positive electrode metal foil 21 can be improved over the whole positive electrode boundary part 18 c provided with the inclined surface 30, and the positive electrode active material layer 22 can be hardly separated from the positive electrode metal foil 21. Such an effect is the same for the negative electrode sheet 19.

  (4) Since the positive electrode boundary portion 18c is corrugated, the total length is increased compared to the case where the positive electrode boundary portion 18c is formed in a straight line, and the positive electrode active material layer 22 is peeled off from the positive electrode metal foil 21. It can be difficult. Such an effect is the same for the negative electrode sheet 19.

  (5) As shown in FIG. 3, in the secondary battery 10, each of the positive electrode sheets 18, the positive electrode terminals 15, and the like is caused by the expansion and contraction of the electrode assembly 12 in the stacking direction with charge / discharge. The positive electrode current collecting tab 24 is repeatedly bent so as to incline toward the positive electrode terminal 15 with the base end as a base point, and a load is applied to the positive electrode boundary portion 18c (indicated by a two-dot chain line). However, in this embodiment, since the positive electrode active material layer 22 and the positive electrode metal foil 21 are sufficiently adhered to each other at the positive electrode boundary portion 18c, the positive electrode active material layer 22 is peeled off from the positive electrode metal foil 21 along with charge / discharge. This can be suppressed. Such an effect is the same for the negative electrode sheet 19.

  (6) Since the plurality of positive current collecting tabs 24 are gathered and connected to the positive terminal 15, the positive current collecting tab 24 is bent so as to incline toward the positive terminal 15 with the base end as a base point. A load is applied to the portion 18c. However, in the positive electrode sheet 18, by providing the inclined surface 30 at the positive electrode boundary portion 18c, the positive electrode active material layer 22 and the positive electrode metal foil 21 are sufficiently adhered to each other at the positive electrode boundary portion 18c. For this reason, in this embodiment, when the positive electrode current collection tab group 24a and the positive electrode terminal 15 are electrically connected, it can suppress that the positive electrode active material layer 22 peels from the positive electrode metal foil 21. FIG. Such an effect is the same for the negative electrode sheet 19.

  (7) As the secondary battery 10, the adhesion with the positive electrode metal foil 21 at the positive electrode boundary portion 18 c of the positive electrode active material layer 22 can be improved, and the positive electrode active material layer 22 can be hardly separated from the positive electrode metal foil 21. Such an effect is the same for the negative electrode sheet 19.

  (8) In the transfer step (formation step), the inclined surface 30 inclined at an angle of 5 ° or more and 45 ° or less with respect to the direction perpendicular to the metal foils 21 and 25 over the entire edge portion 32c of the active material paste 32. In the press process, roll pressing is performed from the edge 32c. Therefore, it is suppressed that the press roll 38a moves by the reaction when contacting the edge 32c of the solidified active material paste 32, and thereby the edge 32c of the active material paste 32 can be sufficiently pressed. Therefore, the adhesiveness with the positive electrode metal foil 21 in the positive electrode boundary part 18 c of the positive electrode active material layer 22 can be improved, and the positive electrode active material layer 22 can be hardly separated from the positive electrode metal foil 21. Such an effect is the same for the negative electrode sheet 19.

  (9) Since the inclined surface 30 is provided at the edge portion 32c on the side of the conveying direction Y1 of the metal foils 21 and 25, the pressing mechanism portion is transferred from the edge portion 32c provided with the inclined surface 30 while conveying the metal foils 21 and 25. 38 can be pressed.

  (10) In the transfer step, the inclined surface 30 is formed on the edge portion 32 c of the active material paste 32. Therefore, a manufacturing process can be simplified compared with the case where the process for exclusive use for forming the inclined surface 30 is provided.

The embodiment is not limited to the above, and may be embodied as follows, for example.
As shown in FIG. 8, the positive electrode non-formation portion 23 is provided along the second positive electrode edge portion 18b, and the positive electrode boundary portion 18d on the second positive electrode edge portion 18b side in the positive electrode active material layer 22 has an inclined surface 30. May be provided. In this case, it is good to roll-press from the positive electrode boundary part 18d in a press process. The negative electrode sheet 19 can be similarly changed.

  As shown in FIG. 9, in the positive electrode metal foil 21, the positive electrode non-formation portion 23 is provided along each edge portion 18 e positioned at both ends of the positive electrode edge portions 18 a and 18 b, and the edge 18 e side in the positive electrode active material layer 22 is provided. An inclined surface 30 may be provided at each positive electrode boundary portion 18f. In this case, it is good to roll-press each from the positive electrode boundary part 18f in a press process. The negative electrode sheet 19 can be similarly changed.

  As shown in FIG. 9, each positive electrode boundary part 18c, 18f may be linear when viewed from the stacking direction. Even in this case, since each of the positive electrode boundary portions 18 c and 18 f is provided with the inclined surface 30, it is possible to prevent the positive electrode active material layer 22 from being separated from the positive electrode metal foil 21. It can change similarly about the positive electrode boundary part 18d in the said embodiment. Further, the negative electrode sheet 19 can be similarly changed.

  As shown in FIG. 10, the inclined surface 30 may be an arc surface that is recessed toward the metal foils 21 and 25. In addition, as shown in FIG. 11, the inclined surface 30 may be an arc surface protruding to the opposite side of the metal foils 21 and 25. In addition, the inclined surface 30 is provided on the non-application part 32b side, and is provided with an arc surface recessed on the metal foils 21 and 25 side, and is provided continuously with the arc surface, and protrudes on the opposite side to the metal foils 21 and 25. It may be a gentle S-curve shape in a side view combined with an arc surface.

  The inclined surface 30 may be provided at an edge that coincides with the edge of the positive electrode sheet 18 that does not have the positive electrode non-forming part 23 among the edges of the positive electrode active material layer 22. The negative electrode sheet 19 can be similarly changed.

The inclined surface 30 may be omitted for one of the positive electrode boundary portion 18 c of the positive electrode sheet 18 and the negative electrode boundary portion 19 c of the negative electrode sheet 19.
(Circle) you may provide the inclined surface 30 in a part of positive electrode boundary part 18c. Moreover, you may provide the inclined surface 30 in a part of negative electrode boundary part 19c. That is, the inclined surface 30 should just be provided in at least one part of each boundary part 18c, 19c.

O You may provide the inclined surface 30 only about the one part positive electrode sheet 18 which comprises the electrode assembly 12, and the one part negative electrode sheet 19. FIG.
○ In the transfer process, the edge 32c of the active material paste 32 is provided with the inclined surface 30 with an inclination angle θ exceeding 45 ° or without the inclined surface 30, and after the drying by the drying furnace 34, the inclination angle θ is obtained by cutting or the like. The inclined surface 30 may be formed so that the angle is 5 ° or more and 45 ° or less. That is, the forming process may be a process different from the transfer process.

  The pressing step may be performed after the strip-like positive electrode metal foil 21 is punched into the shape of the positive electrode sheet 18. That is, the press work may not be performed while being conveyed in the conveyance direction Y1. The negative electrode sheet 19 can be similarly changed.

-You may change the metal which comprises each metal foil 21,25.
The positive electrode sheet 18 may be formed by applying the active material paste 32 to one surface (one surface) of the positive electrode metal foil 21. The negative electrode sheet 19 can be similarly changed.

O You may actualize in electrical storage apparatuses, such as a nickel hydride secondary battery and an electric double layer capacitor.
O You may actualize in the electrical storage apparatus used other than a vehicle.

  θ ... tilt angle, 10 ... lithium ion secondary battery (secondary battery, power storage device), 12 ... electrode assembly, 15 ... positive electrode terminal (external terminal), 16 ... negative electrode terminal (external terminal), 18 ... positive electrode sheet ( Electrode), 18a ... first positive electrode edge (edge), 18c ... positive electrode boundary (edge), 19 ... negative electrode sheet (electrode), 19a ... first negative electrode edge (edge), 19c ... negative electrode boundary (Edge), 20 ... separator, 21 ... positive electrode metal foil (metal foil), 21a ... surface, 22 ... positive electrode active material layer (active material layer), 23 ... positive electrode non-formation part (metal foil exposed part), 24 ... Positive electrode current collecting tab (tab part), 25 ... Negative electrode metal foil (metal foil), 26 ... Negative electrode active material layer (active material layer), 27 ... Negative electrode non-formed part (metal foil exposed part), 28 ... Negative electrode current collecting tab (Tab part), 30 ... inclined surface.

Claims (7)

It has a plurality of electrodes in which an active material layer is formed on at least one surface of the metal foil, and a separator that insulates between the plurality of electrodes, and each electrode overlaps in layers with the separator interposed therebetween A power storage device having a stacked electrode assembly,
At least a part of the edge of the active material layer has an inclined surface that is inclined with respect to a direction perpendicular to the surface of the metal foil;
The power storage device, wherein an inclination angle of the inclined surface is not less than 5 ° and not more than 45 °. The outer shape of the metal foil and the active material layer is rectangular,
The electrode has a metal foil exposed portion where the metal foil is exposed along at least one edge of the metal foil.
2. The power storage device according to claim 1, wherein the inclined surface is provided on at least a part of an edge portion on the metal foil exposed portion side of an edge portion of the active material layer. The outer shape of the metal foil and the active material layer is rectangular,
The power storage device according to claim 1, wherein the inclined surface is provided over at least one of the edges of the active material layer.   The power storage device according to any one of claims 1 to 3, wherein an edge portion having the inclined surface of the edge portion of the active material layer is a wave shape when viewed from a direction perpendicular to the surface of the metal foil.   The edge part which has a metal foil exposed part which this metal foil exposes among the edge parts of the said metal foil has a tab part to which an external terminal is electrically connected, The any one of Claims 1-4 Power storage device.   The power storage device according to claim 1, wherein the power storage device is a secondary battery. A method for manufacturing a power storage device according to any one of claims 1 to 6,
In the surface of the metal foil, the inclined surface that is inclined at an angle of 5 ° or more and 45 ° or less with respect to a direction perpendicular to the surface of the metal foil at least part of the edge of the active material mixture containing an active material Forming step of forming,
And a pressing step of compressing the active material mixture by roll pressing from the edge portion where the inclined surface is formed.