JP2014107035A - Battery and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery, or the like, which can bring close the generation timing of shut-down different dependent on the radial location, when a wound electrode body generates heat abnormally, and can appropriately prevent the wound electrode body from generating heat furthermore to have a high temperature.SOLUTION: A battery 10 includes a wound electrode body 30 formed by winding a strip positive electrode plate 31 and a strip negative electrode plate 41 while superposing them alternately with two porous strip separators 51 composed of thermoplastic resin interposed therebetween. Each separator 51 is made thicker at a site located on the farther radial inside VA of the wound electrode body 30, and made thinner at a site located on the farther radial outside VB.

Description

  The present invention relates to a battery including a wound electrode body obtained by alternately winding a belt-like positive electrode plate and a belt-like negative electrode plate via a belt-like separator, and a method for manufacturing the battery.

The electrode body of the battery is composed of a positive electrode plate, a negative electrode plate, and a separator that electrically insulates them. For example, Patent Document 1 discloses a battery including such an electrode body.
As the separator, a separator made of a thermoplastic resin that is porous and melts and closes its own pores when the temperature exceeds a predetermined temperature is used. When this separator is used, when the electrode body abnormally generates heat above a predetermined temperature due to overcharge or the like, the separator melts and closes its own pores, thereby quickly shutting down the battery reaction via the separator, This is because it is possible to suppress the electrode body from generating heat to a higher temperature.

JP 2000-149906 A

  However, in the case of using a wound electrode body in which a strip-like positive electrode plate and a strip-like negative electrode plate are alternately wound with two strip-shaped separators wound, the diameter of the wound electrode body is used. Since heat is more likely to accumulate in the inner part in the direction, the temperature rises earlier in the radially inner part and to a higher temperature, and the temperature rise is delayed and lower in the radially outer part. For example, a temperature difference of 30 ° C. may occur between the radially innermost part and the outermost part. For this reason, when the wound electrode body abnormally heats up, the part located radially inward of the separator is heated to a predetermined temperature or higher and shuts down to close the holes. On the other hand, it takes a relatively long time to reach a predetermined temperature or higher in a portion located on the outer side in the radial direction of the separator (delayed on the inner side in the radial direction). For this reason, it takes a relatively long time for the separator to melt and close the pores (shut down) (lag behind the radially inner portion).

  As described above, in a battery having a conventional wound electrode body, when abnormal heat is generated, the timing of occurrence of shutdown may differ depending on locations inside and outside in the radial direction of the wound electrode body. For this reason, in the part where the shutdown is delayed, the battery reaction continues and the current concentrates, and the wound electrode body may further generate heat and become high temperature.

  The present invention has been made in view of the current situation, and when the wound electrode body abnormally heats up, it is possible to approach different shutdown occurrence timings depending on the location in the radial direction. Furthermore, it aims at providing the manufacturing method of the battery which can suppress appropriately heat_generation | fever and becoming high temperature, and a battery.

  One aspect of the present invention for solving the above problems is a winding in which a belt-like positive electrode plate and a belt-like negative electrode plate are alternately stacked with two strips made of a porous thermoplastic resin. Each of the separators is a battery that is thicker at a portion located on the radially inner side of the wound electrode body and thinner at a portion located on the outer side in the radial direction.

  The thickness of the separator according to this battery is thicker at a portion located on the radially inner side of the wound electrode body and thinner at a portion located on the radially outer side. For this reason, when the wound electrode body abnormally heats up, the temperature reaches a predetermined temperature earlier in the radially inner portion, but the separator is thicker in the radially inner portion, so that the separator extends over the entire thickness direction. It takes time to melt and block the vacancies so that no battery reaction occurs (no current flows). On the other hand, although the portion of the wound electrode body on the radially outer side reaches a predetermined temperature relatively slowly, the portion of the separator located on the radially outer side is thin, so the separator is melted over the entire thickness direction. As a result, the time until the holes are closed and the battery reaction does not occur (the current stops flowing) can be shortened.

  Therefore, in this battery, when the wound electrode body abnormally heats up, the timing of occurrence of shutdown, which differs depending on the location in the radial direction (differed between the radially inner portion and the radially outer portion), the thickness of the separator It can be made closer to the conventional one that is uniform in the radial direction, and it is possible to appropriately prevent the wound electrode body from further generating heat and becoming high temperature.

Examples of the “winding electrode body” include a cylindrical shape and a flat shape.
The “separator” may be a sheet-like separator independent of the positive electrode plate and the negative electrode plate, or may be a separator layer applied and formed on at least one main surface of the positive electrode plate and the negative electrode plate, as will be described later. Good.
Moreover, the thickness of the separator is gradually changed in the longitudinal direction as a form in which the thickness of the separator is thicker at a portion located on the radially inner side of the wound electrode body and thinner at a portion located on the radially outer side. In addition to the form, a form in which the thickness of the separator is changed stepwise in the longitudinal direction can be mentioned.

  Furthermore, in the battery described above, the separator may be a battery that is a separator layer formed on a main surface of an electrode plate to be applied, at least one of the positive electrode plate and the negative electrode plate.

Since the separator according to this battery is a separator layer coated and formed on at least one of the main surfaces of the positive electrode plate and the negative electrode plate, the separator layer is thicker toward the radially inner side and is separated toward the radially outer side. It can be set as a battery provided with the wound electrode body by which the layer was made thin.
As specific arrangement forms of the two separator layers, for example, forms formed on both main surfaces of the positive electrode plate, forms formed on both main surfaces of the negative electrode plate, and one main surface of the positive electrode plate, respectively. Examples include forms formed on the top and one main surface of the negative electrode plate, respectively.

  Another embodiment includes a wound electrode body in which a belt-like positive electrode plate and a belt-like negative electrode plate are alternately stacked and wound through two separators made of a belt-like porous thermoplastic resin, The separator is a method for manufacturing a battery, in which a portion located on the radially inner side of the wound electrode body is thicker and a portion located on the radially outer side is thinner, and includes a gravure roll. And applying an insulating paste in which thermoplastic resin particles are dispersed in a solvent on the main surface of at least one of the positive electrode plate and the negative electrode plate to form an insulating paste layer. And a drying step of drying the insulating paste layer to form a separator layer that is the separator, and the gravure roll has an outer peripheral length that is less than a longitudinal dimension of the electrode plate to be coated. The outer peripheral surface of the gravure roll is held on the outer peripheral surface as it proceeds from one side to the other side in the circumferential direction of the gravure roll at least in the range of the dimension in the longitudinal direction of the electrode plate to be coated. In the coating process, the thickness of the insulating paste layer advances from one side in the longitudinal direction of the electrode plate to be applied to the other side by the gravure roll. This is a method for manufacturing a battery, which is a step of forming the insulating paste layer in a form that becomes thicker or thinner.

  The gravure roll of the gravure coating apparatus used in this battery manufacturing method has an outer peripheral length that is greater than or equal to the longitudinal dimension of the electrode plate to be coated, and the outer peripheral surface is at least greater than or equal to the longitudinal dimension. As the gravure roll advances from one side in the circumferential direction to the other side, it has a concavo-convex pattern in which the amount of insulating paste held on the outer peripheral surface increases or decreases. In the coating process, the gravure roll forms the insulating paste layer so that the thickness of the insulating paste layer becomes thicker or thinner as it goes from one side to the other side in the longitudinal direction of the coated electrode plate. Thereby, the wound electrode body can be easily and reliably formed with a thicker separator layer (separator) at a radially inner portion and a thinner separator layer (separator) at a radially outer portion.

The “concave / convex pattern” includes, as will be described later, a form constituted by a large number of cells independent from each other and a form constituted by a large number of concave grooves.
Further, specific examples of the “cell” include a rectangular shape in plan view, a polygonal shape in plan view such as a hexagonal shape in plan view, a circular shape in plan view, an elliptical shape in plan view, and an elliptical shape in plan view. Can be mentioned.
Further, as a specific form of the “concave groove”, a concave groove extending parallel to the circumferential direction of the gravure roll, a concave groove extending obliquely with respect to the circumferential direction of the gravure roll, and the width direction (axial direction) of the gravure roll A concave groove extending in parallel may be mentioned. Moreover, you may combine these concave grooves.

  In addition, as an uneven pattern in which the amount of insulating paste retained increases or decreases as it proceeds from one side in the circumferential direction of the gravure roll to the other side, the amount of insulating paste retained is from one side in the circumferential direction to the other side. As it progresses, the form which gradually increases or decreases, and the form which increases or decreases stepwise are mentioned. Specifically, the number of cells per unit area on the outer peripheral surface, the area and depth of each cell, or the width and depth of the groove are gradually or stepwisely increased from one side to the other side in the circumferential direction. In other words, the capacity of the cell or the groove per unit area of the outer peripheral surface is increased or decreased as it proceeds from one side to the other side in the circumferential direction.

  Further, in the battery manufacturing method, the uneven pattern on the outer peripheral surface is composed of a large number of cells independent from each other, and the capacity of the cell per unit area of the outer peripheral surface is determined by the circumference of the gravure roll. A method of manufacturing a battery that is larger or smaller as it proceeds from one side of the direction to the other side is preferable.

  By adopting such a concavo-convex pattern on the outer peripheral surface of the gravure roll, it is possible to easily and reliably form the concavo-convex pattern in which the amount of the insulating paste to be held is changed in the circumferential direction as described above.

  Furthermore, in any of the above-described battery manufacturing methods, the uneven pattern on the outer peripheral surface may be a battery manufacturing method formed by laser engraving.

  By forming the concavo-convex pattern by laser engraving, it is possible to easily and reliably form the concavo-convex pattern in which the amount of the insulating paste to be held is changed in the circumferential direction as described above.

  Another embodiment includes a wound electrode body in which a belt-like positive electrode plate and a belt-like negative electrode plate are alternately stacked and wound through two separators made of a belt-like porous thermoplastic resin, The separator is a method for manufacturing a battery, in which a portion located on the radially inner side of the wound electrode body is thicker and a portion located on the radially outer side is thinner, and includes a gravure roll. And applying an insulating paste in which thermoplastic resin particles are dispersed in a solvent on the main surface of at least one of the positive electrode plate and the negative electrode plate to form an insulating paste layer. And a drying step of drying the insulating paste layer to form a separator layer that is the separator. The gravure roll has, on its outer peripheral surface, a width direction and a circumference of the gravure roll. A plurality of concave grooves extending at least in the circumferential direction are arranged at regular intervals, and the gravure coating apparatus includes a doctor blade that scrapes off the insulating paste on the outer peripheral surface, and the gravure roll. And a pump for changing the hydraulic pressure applied to the insulating paste stored between the doctor blade and the coating process, the hydraulic pressure is changed by the pump and scraped off by the doctor blade. The amount of the insulating paste retained on the outer peripheral surface after the increase or decrease, and the thickness of the insulating paste layer becomes thicker or thinner as it advances from one side to the other side in the longitudinal direction of the electrode plate to be coated And a method of manufacturing a battery, which is a step of forming the insulating paste layer.

  In the gravure coating apparatus used in this battery manufacturing method, the outer peripheral surface of the gravure roll has an uneven pattern in which a large number of concave grooves extending at least in the circumferential direction of the gravure roll are arranged at regular intervals. Further, the gravure coating apparatus includes a doctor blade that scrapes off the insulating paste on the outer peripheral surface of the gravure roll, and a pump that changes the hydraulic pressure applied to the insulating paste stored between the gravure roll and the doctor blade. In the coating process, the amount of the insulating paste retained on the outer peripheral surface after being scraped by the doctor blade by changing the hydraulic pressure of the insulating paste gradually or stepwise with a pump (of the electrode plate to be coated) The amount of insulating paste transferred onto the main surface is increased or decreased, and the insulating paste layer is formed so that the thickness of the insulating paste layer becomes thicker or thinner as it goes from one side to the other side in the longitudinal direction of the electrode plate to be coated. Form.

  Specifically, when hydraulic pressure is applied to the insulating paste stored between the gravure roll and the doctor blade by a pump, the rotation of the gravure roll proceeds more than the doctor blade through the concave groove extending in the circumferential direction through the doctor blade. Insulating paste is extruded onto the groove on the direction side. Therefore, when the fluid pressure is increased or decreased, the amount of insulating paste transferred onto the main surface of the electrode plate to be applied also increases or decreases. Therefore, by increasing or decreasing the hydraulic pressure, the insulating paste layer can be formed in a form in which the thickness of the insulating paste layer increases or decreases as it advances from one side in the longitudinal direction of the coated electrode plate to the other side. By doing so, it is possible to easily and reliably form a wound electrode body having a thicker separator layer (separator) at a radially inner portion and a thinner separator layer (separator) at a radially outer portion.

  Specific examples of the “concave groove” include a concave groove extending parallel to the circumferential direction of the gravure roll and a concave groove extending obliquely with respect to the circumferential direction of the gravure roll. Moreover, you may combine these.

1 is a longitudinal sectional view of a battery according to Embodiment 1. FIG. FIG. 4 is a perspective view of a wound electrode body according to the first embodiment. FIG. 3 is an explanatory diagram schematically illustrating the arrangement of a positive electrode plate, a negative electrode plate, and a separator according to the first embodiment, as viewed from above in FIG. 2 of a wound electrode body. FIG. 3 is a partial enlarged cross-sectional view of a wound electrode body according to the first embodiment. FIG. 4 is a partial plan view showing a state in which the positive electrode plate and the negative electrode plate having separator layers on both main surfaces are overlapped with each other according to the first embodiment. It is sectional drawing which concerns on Embodiment 1 and follows the longitudinal direction of the negative electrode plate which has a separator layer on both main surfaces. It is explanatory drawing which shows a mode that it concerns on Embodiment 1 and apply | coats an insulating paste on the main surface of a negative electrode plate in a coating process. It is related with the uneven | corrugated pattern formed in the outer peripheral surface of the gravure roll of Embodiment 1, (a) is a pattern top view, (b) is AA sectional drawing in (a). It is explanatory drawing which shows a mode that it concerns on Embodiment 2 and apply | coats an insulating paste on the main surface of a negative electrode plate in a coating process. It is related with the uneven | corrugated pattern formed in the outer peripheral surface of the gravure roll of Embodiment 2, (a) is a pattern top view, (b) is BB sectional drawing in (a).

(Embodiment 1)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a cylindrical battery 10 according to the first embodiment. 2 to 5 show a cylindrical wound electrode body 30 constituting the battery 10 and a developed state thereof. Further, FIG. 6 shows a negative electrode plate 41 having a separator layer 51 on both main surfaces 41a and 41b. The battery 10 is a cylindrical (18650 type) lithium ion secondary battery mounted on a vehicle such as a hybrid vehicle or an electric vehicle or a battery-powered device such as a hammer drill. The battery capacity is 500 mAh. The battery 10 includes a cylindrical battery case 20, a cylindrical wound electrode body 30 accommodated in the battery case 20, a positive electrode current collector plate 60 connected to the wound electrode body 30, and It is comprised from the negative electrode current collecting plate 70 grade | etc., (Refer FIG. 1). Further, a non-aqueous electrolyte solution 27 is held in the battery case 20.

  Among these, the battery case 20 is made of metal (specifically, aluminum). The battery case 20 has a bottomed cylindrical shape in which one side KC in the case axis KX direction (upward in FIG. 1) is open, and the other side KD in the case axis KX direction (down in FIG. 1) is closed. The main body member 21 and a substantially disk-shaped lid member 23 that seals the opening 21h of the main body member 21 are configured. Specifically, the lid member 23 is caulked and fixed to the opening 21 h of the main body member 21 via a ring-shaped seal member 25. The body member 21 is electrically connected to the negative electrode current collector plate 70 as will be described later, and also serves as the negative electrode terminal of the battery 10. On the other hand, the lid member 23 is electrically connected to the positive electrode current collector plate 60 via a lead member 61 as will be described later, and also serves as the positive electrode terminal of the battery 10.

  Next, the wound electrode body 30 will be described. The wound electrode body 30 has a cylindrical shape having a winding axis AX, and is accommodated in the battery case 20 in a form in which the winding axis AX coincides with the above-described case axis KX (FIGS. 1 to 1). (See FIG. 4). Specifically, the wound electrode body 30 is accommodated in the battery case 20 in a state where the periphery is covered with a cylindrical insulating film 29 made of resin.

  This wound electrode body 30 includes a belt-like positive electrode plate 31 and a belt-like negative electrode plate 41 (see FIG. 6) having separator layers (separators) 51 and 51 on both main surfaces 41a and 41b, respectively. (See FIG. 5) and wound around the winding axis AX (see FIGS. 2 to 4). Note that the dimension La (specifically La = 1000 mm) in the longitudinal direction NY of the negative electrode plate 41 having the separator layer 51 is longer than the dimension (specifically, 990 mm) in the longitudinal direction of the positive electrode plate 31. In the negative electrode plate 41 and the separator layer 51, the portion located on the innermost radial direction VA and the portion located on the outermost radial direction VB of the wound electrode body 30 do not face the positive electrode plate 31, respectively. It is abandoned (see FIG. 3).

  The positive electrode plate 31 has a strip-shaped positive electrode foil 32 made of aluminum as a core material. On both main surfaces of the positive electrode foil 32, a part of the width direction (vertical direction in FIGS. 1, 2, and 5) (downward in FIGS. 1, 2, and 5) is disposed on the longitudinal direction. Positive electrode active material layers 33, 33 extending in a strip shape in the direction (left-right direction in FIG. 5) are formed. The positive electrode active material layer 33 includes a positive electrode active material (specifically, lithium, cobalt, nickel, manganese composite oxide), a conductive material (specifically, acetylene black (AB)), and a binder (specifically, Is made of polyvinylidene fluoride (PVDF). In the positive electrode plate 31, a belt-like portion where the positive electrode foil 32 and the positive electrode active material layer 33 are present in the thickness direction is the positive electrode portion 31 w. On the other hand, the positive electrode current collector 31m is a belt-shaped portion made of only the positive electrode foil 32 without the positive electrode active material layer 33 in the thickness direction of the positive electrode plate 31.

  A part of the positive electrode plate 31 in the width direction (a part of the positive electrode current collector 31m) is one side AC in the winding axis AX direction from the negative electrode plate 41 and the separator layer 51 (in FIG. 1, FIG. 2, and FIG. ) In a spiral shape and is connected (welded) to the disc-shaped positive current collector plate 60. A lead member 61 is connected (welded) to the positive electrode current collector plate 60 at one side KC in the direction of the case axis KX. The lead member 61 is connected (welded) to the lid member 23 of the battery case 20 on the other side. A disc-shaped insulating plate 28 made of resin is disposed between the positive electrode current collector plate 60 and the lid member 23.

  The negative electrode plate 41 has a strip-shaped negative electrode foil 42 made of copper as a core material. On both main surfaces of the negative electrode foil 42, a part of the width direction (vertical direction in FIGS. 1, 2, and 5) (upward in FIGS. 1, 2, and 5) Negative electrode active material layers 43, 43 extending in a strip shape in the direction (left-right direction in FIG. 5) are formed. The negative electrode active material layer 43 includes a negative electrode active material (specifically, graphite), a binder (specifically, styrene-butadiene rubber (SBR)), and a thickener (specifically, carboxymethylcellulose (CMC). )). In the negative electrode plate 41, a strip-shaped portion where the negative electrode foil 42 and the negative electrode active material layer 43 exist in the thickness direction of the negative electrode plate 41 is the negative electrode portion 41w. On the other hand, in the negative electrode plate 41, a strip-shaped portion made only of the negative electrode foil 42 without the negative electrode active material layer 43 in the thickness direction of itself is the negative electrode current collector 41m.

  A part of the negative electrode plate 41 in the width direction (negative electrode current collector 41m) spirals from the positive electrode plate 31 and the separator layer 51 to the other side AD (downward in FIGS. 1, 2, and 5) in the winding axis AX direction. It protrudes in a shape and is connected (welded) to the disc-shaped negative electrode current collector plate 70. The negative electrode current collector plate 70 is connected (welded) to the main body member 21 of the battery case 20 on the other side KD in the case axis KX direction.

  Band-shaped separator layers 51 and 51 are formed on both main surfaces 41a and 41b of the negative electrode plate 41, specifically on the negative electrode active material layers 43 and 43, respectively (see FIG. 6). These separator layers 51 and 51 are interposed between the positive electrode plate 31 and the negative electrode plate 41 in the state in which the wound electrode body 30 is configured (see FIG. 4). The separator layer 51 is made of a porous thermoplastic resin (specifically, polyethylene (PE)), and melts at a predetermined temperature (130 ° C. in the first embodiment) to close the pores. It insulates from the negative electrode plate 41, and the electric current which flows between these is shut down.

The separator layer 51 is configured such that its thickness t decreases as it goes from the site on one side NA to the site on the other side NB in the longitudinal direction NY of the negative electrode plate 41 (as it goes to the right in FIG. 6). Yes. In the state where the wound electrode body 30 is configured, the negative electrode plate 41 is disposed so that the portion where the separator layer 51 is located on the radially inner side VA is thicker and the portion where the separator layer 51 is located on the radially outer side VB is thinner. is there.
In the following, in the longitudinal direction NY of the negative electrode plate 41, in the state in which the wound electrode body 30 is configured, the orientation to be positioned on the radially inner side VA is the orientation to be positioned on the longitudinal inner direction NA and the radially outer side VB. The longitudinal outer direction NB is assumed. According to this, as the separator layer 51 goes from the site in the longitudinal inner direction NA toward the site in the longitudinal outer direction NB (as it goes from the site in the radial inner side VA to the site in the radial outer side VB of the wound electrode body 30). It can be said that the thickness t is gradually reduced.

  In the battery of the first embodiment, the thickness t1 of the end portion 51a in the longitudinal inner direction NA (the portion located at the most radially inner side VA in the wound electrode body 30) of the separator layer 51 is t1 = 30 μm, The thickness t2 of the end portion 51b in the longitudinal outer side direction NB (the portion located on the most radially outer side VB in the wound electrode body 30) is t2 = 25 μm. Since the dimension in the longitudinal direction of the separator layer 51 (dimension La in the longitudinal direction NY of the negative electrode plate 41) is La = 1000 mm (= 1.000 m) as described above, the separator layer 51 has a ratio of 5 μm / m. The thickness t changes gradually.

  As described above, in the battery 10, the thickness t of the separator layer 51 is made thicker at a portion located on the radially inner side VA of the wound electrode body 30 and thinner at a portion located on the radially outer side VB. is there. For this reason, when the wound electrode body 30 abnormally heats up due to overcharge or the like, the part of the radially inner VA reaches a predetermined temperature earlier, but the part of the separator layer 51 located at the radially inner VA has a thickness t. Therefore, it takes time until the separator layer 51 is melted over the entire thickness direction TY and the vacancies are blocked, and the battery reaction does not occur (the current does not flow). On the other hand, although the portion of the wound electrode body 30 on the radially outer side VB relatively slowly reaches a predetermined temperature, the portion of the separator layer 51 located on the radially outer side VB has a small thickness t. The time until the layer 51 is melted over the entire thickness direction TY to close the vacancies and no battery reaction occurs (no current flows) can be shortened.

  Therefore, in this battery 10, when the wound electrode body 30 abnormally generates heat, the timing of occurrence of shutdown differs depending on the location in the radial direction VY (differing between the location in the radial direction VA and the location in the radial direction VB). As compared with the conventional battery in which the thickness t of the separator layer is uniform in the radial direction VY, the separator layer can be made closer. More specifically, in the first embodiment, the shutdown occurrence timing can be aligned in the radial direction, and the wound electrode body 30 can be appropriately suppressed from further generating heat and becoming high temperature.

  Furthermore, in the first embodiment, the separator 51 is a separator layer that is applied and formed on both the main surfaces 41a and 41b of the negative electrode plate 41. Therefore, the separator layer 51 is thicker easily and reliably at a portion on the radially inner side VA. The battery 10 can be provided with the wound electrode body 30 in which the separator layer 51 is made thinner toward the radially outer side VB.

  Next, a method for manufacturing the battery 10 will be described. First, the positive electrode plate 31 is manufactured. That is, a strip-shaped positive electrode foil 32 is prepared. Then, using a die coater, a positive electrode paste containing a positive electrode active material, a conductive material, and a binder is applied to a part of one main surface of the positive electrode electrode foil 32 in the width direction, and this is heated with hot air. It is made to dry and the positive electrode active material layer 33 is formed (refer FIG. 5). Similarly, the positive electrode paste is applied to a main surface on the opposite side of the positive electrode foil 32 on a part in the width direction, and dried with hot air to form the positive electrode active material layer 33. Thereafter, the positive electrode active material layer 33 is compressed by a pressure roll to increase its density. Thus, the positive electrode plate 31 is formed.

  Separately, the negative electrode plate 41 is manufactured. That is, a strip-shaped negative electrode foil 42 is prepared. Then, using a die coater, a negative electrode paste containing a negative electrode active material, a binder, and a thickener is applied onto a part of one main surface of the negative electrode foil 42 in the width direction. To form a negative electrode active material layer 43 (see FIG. 6). Similarly, the negative electrode paste is applied to a main surface on the opposite side of the negative electrode foil 42 on a part in the width direction, and dried with hot air to form the negative electrode active material layer 43. Thereafter, the negative electrode active material layer 43 is compressed by a pressure roll to increase its density. Thus, the negative electrode plate 41 is formed.

  Next, separator layers (separators) 51, 51 are formed on both main surfaces 41 a, 41 b of the negative electrode plate (coated electrode plate) 41. First, an insulating paste ZP in which thermoplastic resin particles are dispersed in a solvent is prepared. In the first embodiment, polyethylene (PE) particles are used as thermoplastic resin particles, water is used as a solvent, and a thickener is further added to produce an insulating paste ZP. Then, in the coating process, using the gravure coating apparatus 100, this insulating paste ZP is applied onto one main surface 41a of the negative electrode plate 41 (specifically, on the negative electrode active material layer 43), and the insulating paste layer 51p is formed (see FIGS. 7 and 6).

  The gravure coating apparatus 100 includes a gravure roll 110, a doctor blade 120, a liquid tank 130, and an impression cylinder roll 135 (see FIGS. 7 and 8). Among these, the gravure roll 110 transfers and applies the insulating paste ZP held on the outer peripheral surface 110 a onto the main surface 41 a of the negative electrode plate 41. The doctor blade 120 scrapes off the excess insulating paste ZP adhering to the outer peripheral surface 110a of the gravure roll 110. The liquid tank 130 stores the insulating paste ZP and supplies the insulating paste ZP to the outer peripheral surface 110 a of the gravure roll 110. The impression cylinder roll 135 is made of rubber, and presses the negative electrode plate 41 on the gravure roll 110 so that the insulating paste ZP is appropriately transferred from the gravure roll 110 onto the main surface 41a of the negative electrode plate 41.

  The gravure roll 110 will be further described. The gravure roll 110 has an outer peripheral length Lb that is greater than or equal to a dimension La in the longitudinal direction NY of the negative electrode plate 41. In the first embodiment, the outer peripheral length Lb = 1000 mm, which is equal to the dimension La = 1000 mm in the longitudinal direction NY of the negative electrode plate 41. Further, the outer peripheral surface 110a of the gravure roll 110 is gradually reduced in the amount of the insulating paste ZP held on the outer peripheral surface 110a as it proceeds from the one side SA in the circumferential direction SH to the other side SB in the entire circumferential direction SH. It has a concavo-convex pattern (engraving) 111 (see FIG. 8).

Specifically, the concavo-convex pattern 111 is composed of a large number of cells 112 independent of each other. Each of the cells 112 is a hexagonal recess in plan view, and these cells are densely arranged so that the uneven pattern 111 has a honeycomb shape. Each cell 112 is gradually reduced in size (hexagonal area and depth) from one side SA in the circumferential direction SH to the other side SB, whereby the unit area of the outer circumferential surface 110a. The capacity of the winning cell 112 is gradually reduced from the one side SA in the circumferential direction SH to the other side SB. Specifically, the capacity of the cell 112 per unit area of the outer peripheral surface 110a is 100 cm ³ / m ^{2 at} the largest part and 90 cm ³ / m ² at the smallest part. The uneven pattern 111 is formed by laser engraving.

In the coating process, the gravure roll 110 is used, and the thickness of the insulating paste layer 51p is gradually reduced from one side (longitudinal inner direction) NA to the other side (longitudinal outer direction) NB of the negative electrode plate 41 in the longitudinal direction NY. An insulating paste layer 51p is formed in such a form (see FIGS. 7 and 6). As described above, since the outer peripheral length Lb of the gravure roll 110 is equal to the dimension La in the longitudinal direction NY of the negative electrode plate 41, the length of the negative electrode plate 41 for one revolution every time the gravure roll 110 rotates once. An insulating paste layer 51p is formed over the entire area.
After the coating process, in the drying process, the insulating paste layer 51p formed on the main surface 41a of the negative electrode plate 41 is dried with hot air to form the separator layer 51.

  Next, the coating process is performed again, and the insulating paste ZP is applied to the main surface 41b on the opposite side of the negative electrode plate 41 (on the negative electrode active material layer 43) using the gravure coating apparatus 100, and the insulating paste layer 51p is formed (see FIGS. 7 and 6). Thereafter, a drying step is performed to dry the insulating paste layer 51p formed on the main surface 41b of the negative electrode plate 41, thereby forming the separator layer 51. Then, if this is cut for each dimension La in the longitudinal direction NY, separator layers 51 and 51 are formed on both main surfaces 41a and 41b, with thickness t gradually decreasing from one side NA to the other side NB. A negative electrode plate 41 is obtained.

Next, the positive electrode plate 31 and the negative electrode plate 41 on which the separator layers 51 and 51 are formed are overlapped with each other (see FIG. 5), wound around the winding axis AX using a winding core, and wound type The electrode body 30 is formed.
Next, the positive electrode current collector plate 60 is prepared and welded to the positive electrode current collector 31 m of the wound electrode body 30. Further, a lead member 61 and a lid member 23 are prepared, and one end side of the lead member 61 is welded to the positive electrode current collector plate 60 and the lid member 23 on the other end side. At that time, the insulating plate 28 is interposed between the positive electrode current collector plate 60 and the lid member 23. Moreover, the negative electrode current collecting plate 70 is prepared and welded to the negative electrode current collecting part 41 m of the wound electrode body 30. Further, the periphery of the wound electrode body 30 is covered with an insulating film 29.

  Next, the main body member 21 of the battery case 20 is prepared, and the wound electrode body 30 and the like connected with the positive current collector plate 60 and the like are inserted therein. Thereafter, the negative electrode current collector plate 70 is welded to the main body member 21. Next, the electrolyte solution 27 is injected into the main body member 21, and then the lid member 23 is swaged and fixed via the seal member 25 to close the opening 21 h of the main body member 21. Thereafter, the battery is subjected to initial charging and various inspections. Thus, the battery 10 is completed.

  The gravure roll 110 of the above-described gravure coating apparatus 100 used in the method for manufacturing the battery 10 has an outer peripheral length Lb having a dimension La in the longitudinal direction NY of the negative electrode plate 41, and an outer peripheral surface 110a having the entire circumferential direction SH. As a result, there is a concavo-convex pattern 111 in which the amount of the insulating paste ZP held on the outer peripheral surface 110a decreases as it proceeds from one side SA in the circumferential direction SH to the other side SB. In the coating process, the gravure roll 110 forms the insulating paste layer 51p in such a form that the thickness of the insulating paste layer 51p becomes thinner as it proceeds from one side NA in the longitudinal direction NY of the negative electrode plate 41 to the other side NB. . By doing in this way, the thickness t of the separator layer 51 formed in the subsequent drying step gradually decreases as it proceeds in the longitudinal direction NY of the negative electrode plate 41. Therefore, by using the negative electrode plate 41 on which the separator layer 51 is formed, the wound electrode body 30 can be easily formed such that the separator layer 51 is thicker in the radially inner VA region and the separator layer 51 is thinner in the radially outer VB region. And it can be formed reliably.

  Further, in the first embodiment, the concave / convex pattern 111 of the gravure roll 110 is composed of a large number of cells 112 independent from each other, and the capacity of the cell 112 per unit area advances from one side SA in the circumferential direction SH to the other side SB. It is made into the form which becomes small gradually as it goes. In particular, in the first embodiment, the uneven pattern 111 is formed by laser engraving. For this reason, the uneven | corrugated pattern 111 which changed the quantity of the insulation paste ZP hold | maintained as mentioned above to the circumferential direction SH can be formed easily and reliably.

(Embodiment 2)
Next, a second embodiment will be described. In the manufacturing method of the battery 10 according to the second embodiment, the coating process in the formation of the separator layer (separator) 51 and the gravure coating apparatus 200 used therefor are the coating process and the gravure coating apparatus 100 according to the first embodiment. And different. Other than that, the second embodiment is the same as the first embodiment, and the description of the same parts as the first embodiment is omitted or simplified.

The gravure coating apparatus 200 according to the second embodiment includes a gravure roll 210, a doctor blade 220, a seal blade 225, a liquid tank 230, a storage tank 240, a pump 245, a pressure gauge 250, a pipe 255, and the like. 256 (see FIGS. 9 and 10).
Among these, the gravure roll 210 applies the insulating paste ZP held on the outer peripheral surface 210 a onto the main surface 41 a of the negative electrode plate 41. The outer peripheral surface 210a has a concavo-convex pattern (engraving) 211 in which a large number of concave grooves 212 extending in at least the circumferential direction SH among the width direction WH and the circumferential direction SH of the gravure roll 210 are arranged at regular intervals. In the second embodiment, each of the concave grooves 212 has a V-shaped cross section and linearly extends obliquely with respect to the circumferential direction SH (intersects at θ = 45 °) (see FIG. 10). The respective grooves 212 are arranged at regular intervals, and the capacity of the grooves 212 per unit area of the outer peripheral surface 210a is different from the capacity of the cell 112 according to the first embodiment changing in the circumferential direction SH. It is constant regardless of location. The uneven pattern 211 is also formed by laser engraving. Note that the concave / convex pattern 211 may be formed by mechanical engraving that presses the base material to produce the concave / convex pattern.

  The doctor blade 220 scrapes off the excess insulating paste ZP adhering to the outer peripheral surface 210a of the gravure roll 210. The liquid tank 230 temporarily stores the insulating paste ZP and supplies it to the outer peripheral surface 210a of the gravure roll 210. The seal blade 225 seals the space between the gravure roll 210 and the liquid tank 230 together with the doctor blade 220 to seal the inside of the liquid tank 230 from the outside. The storage tank 240 stores the insulating paste ZP, and is connected to the liquid tank 230 via pipes 255 and 256.

  The pump 245 is disposed between the storage tank 240 and the liquid tank 230 and sends the insulating paste ZP from the storage tank 240 to the liquid tank 230 through the pipe 256. Further, by controlling the rotational speed of the pump 245, the hydraulic pressure Pz of the insulating paste ZP in the liquid tank 230 (the hydraulic pressure Pz applied to the insulating paste ZP stored between the gravure roll 210 and the doctor blade 220). To change. Moreover, the pressure gauge 250 is arrange | positioned between the pump 245 and the liquid tank 230, and detects the hydraulic pressure Pz applied to the insulation paste ZP.

  In the coating process of the second embodiment, the hydraulic pressure Pz of the insulating paste ZP, and hence the hydraulic pressure Pz applied to the insulating paste ZP stored between the gravure roll 210 and the doctor blade 220 is gradually lowered by the pump 245. . Specifically, the hydraulic pressure Pz is gradually lowered from a maximum of 3.2 kPa to a minimum of 2.1 kPa over the printing time of one negative electrode plate 41. Then, the amount of the insulating paste ZP held on the outer peripheral surface 210a after being scraped off by the doctor blade 220 is gradually reduced. Such a decrease period of the hydraulic pressure Pz and a rapid increase period in which the hydraulic pressure Pz is rapidly increased from 2.1 kPa to 3.2 kPa were repeated. As a result, the thickness of the insulating paste layer 51p is gradually reduced from one side (longitudinal inner direction) NA to the other side (longitudinal outer direction) NB in the longitudinal direction NY of the negative electrode plate (coated electrode plate) 41. Then, an insulating paste layer 51p is formed (see FIGS. 9 and 10).

Specifically, when the hydraulic pressure Pz is applied to the insulating paste ZP stored between the gravure roll 210 and the doctor blade 220 by the pump 245, the doctor blade 220 passes through the concave groove 212 extending in the circumferential direction SH. The insulating paste ZP is pushed out onto the concave groove 212 on the rotation traveling direction side RA of the gravure roll 210 relative to the blade 220. Therefore, when the hydraulic pressure Pz is increased or decreased, the amount of the insulating paste ZP transferred onto the main surface 41a of the negative electrode plate 41 is also increased or decreased. Therefore, by gradually reducing the hydraulic pressure Pz, the thickness of the insulating paste layer 51p is gradually reduced from the one side NA in the longitudinal direction NY of the negative electrode plate 41 to the other side NB. Can be formed.
After the coating process, the drying process is performed in the same manner as in the first embodiment, and the insulating paste layer 51p formed on the main surface 41a of the negative electrode plate 41 is dried to form the separator layer 51.

  Further, the coating process and the drying process are performed again, and the separator layer 51 is similarly formed on the main surface 41 b on the opposite side of the negative electrode plate 41. After that, if this is cut for each dimension La in the longitudinal direction NY, the separator layer 51, the thickness t of which gradually decreases from the one side NA to the other side NB in the longitudinal direction NY on both main surfaces 41a and 41b. A negative electrode plate 41 having 51 formed thereon is obtained. Thereafter, the battery 10 is completed in the same manner as in the first embodiment.

  As described above, in the gravure coating apparatus 200 according to the second embodiment, the outer peripheral surface 210a of the gravure roll 210 is uneven with a large number of concave grooves 212 extending in the circumferential direction SH of the gravure roll 210 arranged at regular intervals. It has a pattern 211. The gravure coating apparatus 200 includes a doctor blade 220 and a pump 245 that changes a hydraulic pressure Pz applied to the insulating paste ZP stored between the gravure roll 210 and the doctor blade 220.

  In the coating process, the amount of the insulating paste ZP retained on the outer peripheral surface 210a after being scraped by the doctor blade 220 by gradually changing the hydraulic pressure Pz of the insulating paste ZP with the pump 245 (the negative electrode plate 41). The amount of the insulating paste ZP transferred onto the main surfaces 41a and 41b is gradually reduced, and the thickness of the insulating paste layer 51p gradually increases from one side NA in the longitudinal direction NY of the negative electrode plate 41 to the other side NB. An insulating paste layer 51p is formed in a thinned form. By doing in this way, the separator layer 51 formed in the subsequent drying step gradually decreases in thickness t as it proceeds from one side NA in the longitudinal direction NY of the negative electrode plate 41 to the other side NB. Therefore, by using the negative electrode plate 41 on which the separator layer 51 is formed, the wound electrode body 30 can be easily formed such that the separator layer 51 is thicker in the radially inner VA region and the separator layer 51 is thinner in the radially outer VB region. And it can be formed reliably.

(Examples and Comparative Examples)
Next, the results of tests performed to verify the effects of the battery 10 and the manufacturing method thereof according to Embodiments 1 and 2 will be described. As Example 1, a battery 10 (18650 type, battery capacity 500 mAh) according to Embodiment 1 was manufactured. In the battery 10, as described above, the thickness t of the separator layer 51 is thicker at a portion located on the radially inner side VA of the wound electrode body 30 and thinner at a portion located on the radially outer side VB. Specifically, in the separator layer 51, the thickness t1 of the end portion 51a positioned at the innermost radial direction VA is t1 = 30 μm, and the thickness t2 of the end portion 51b positioned at the outermost radial direction VB is t2 = 25 μm. It is. The dimension La in the longitudinal direction NY of the negative electrode plate 41 (the dimension in the longitudinal direction of the separator layer) is La = 1000 mm, and the dimension in the longitudinal direction of the positive electrode plate 31 is 990 mm.

In the battery according to Example 2, the dimension La in the longitudinal direction NY of the negative electrode plate was La = 800 mm, and the dimension in the longitudinal direction of the positive electrode plate was 790 mm. Further, the separator layer formed on the negative electrode plate is thicker at the portion where the thickness t is located on the radially inner side VA of the wound electrode body (the thickness t1 of the portion located on the innermost radial direction VA is t1 = 29 μm), and the diameter The portion positioned on the outer side VB is thinner (the thickness t2 of the portion positioned on the outermost radial direction VB is t2 = 25 μm).
In the battery according to Example 3, the dimension La in the longitudinal direction NY of the negative electrode plate was La = 1200 mm, and the dimension in the longitudinal direction of the positive electrode plate was 1190 mm. Further, the thickness of the separator layer formed on the negative electrode plate is thicker in the portion where the thickness t is located on the radially inner side VA of the wound electrode body (the thickness t1 of the portion located on the innermost radial direction VA is t1 = 31 μm). The portion positioned on the outer side VB is thinner (the thickness t2 of the portion positioned on the outermost radial direction VB is t2 = 25 μm).

  On the other hand, in the battery according to Comparative Example 1, the thickness t of the separator layer was set to a constant thickness (specifically 25 μm) regardless of the location in the radial direction VY of the wound electrode body. Otherwise, the battery 10 was the same as that of Example 1 (Embodiment 1).

  And about each battery which concerns on Examples 1-3 and Comparative Example 1, the "overcharge test" was done and the leakage current and the maximum temperature of the battery were calculated | required, respectively. Specifically, each battery was overcharged until the battery voltage reached 10 V at a current value of 5 C (2500 mA). When the battery is overcharged, internal discharge occurs with the decomposition of the electrolytic solution, and the battery voltage temporarily decreases from 10V to about 5V. On the other hand, since the current continues to flow, the battery continues to generate heat and the battery temperature continues to rise. After that, when the battery temperature rises, the separator melts and begins to block its own vacancies, so that the battery reaction via the separator does not suddenly occur (current suddenly stops almost flowing) or the battery reaction suddenly decreases. (The current suddenly decreases). On the other hand, the battery voltage, which was about 5V, recovers to about 10V. In this overcharge test, the current value was measured 5 minutes after the battery voltage recovered to about 10 V, and this was taken as the leakage current (mA). Further, the battery temperature was measured at intervals of 1 second until the battery temperature tended to decrease after the battery voltage recovered to 10 V, and the maximum battery temperature (° C.) during that period was determined. The results are shown in Table 1.

  As can be seen from Table 1, the battery according to Comparative Example 1 had a large leakage current of 300 mA and the highest battery temperature was 201 ° C. (determination was poor and “x”). The reason is as follows. That is, as described above, in the wound electrode body, the heat is more likely to be accumulated in the radially inner VA portion, so that the temperature rises earlier in the radially inner VA portion and the temperature is higher in the radially outer VB portion. The temperature rise is delayed and the temperature becomes low. For this reason, when the wound electrode body heats up abnormally in the above-described overcharge test, the portion located on the radially inner side VA of the separator is heated to a predetermined temperature or higher and melts to close the holes. On the other hand, it takes a relatively long time to reach a predetermined temperature or higher as the portion located on the radially outer side VB of the separator. For this reason, it takes a relatively long time for the separator to melt and close the holes. Therefore, although the battery reaction suddenly decreases as described above, it is considered that a relatively large leakage current flows because the battery reaction continues through the portion of the radially outer side VB that has not been closed. In addition, it is considered that the current concentrated on the part where the hole was not closed, and the wound electrode body further generated heat and became high temperature.

  On the other hand, in each battery according to Examples 1 to 3, the leakage current was 2 to 5 mA, and the maximum temperature of the battery was a low value of 110 to 120 ° C. "). The reason is as follows. In these batteries, the thickness t of the separator layer 51 and the like is thicker at a portion located on the radially inner side VA of the wound electrode body and thinner at a portion located on the radially outer side VB. For this reason, when the wound electrode body abnormally generates heat in the overcharge test described above, the temperature reaches the predetermined temperature earlier in the radially inner VA region, but the portion of the separator located in the radially inner VA has a thickness. Since it is thick, it takes time for the separator to melt throughout the thickness direction and to close the pores. On the other hand, although the portion of the wound electrode body radially outside VB relatively slowly reaches a predetermined temperature, the portion of the separator located on the radially outer side VB is thin, so the separator is entirely in the thickness direction. It takes only a short time until the holes are melted and the holes are closed. Therefore, when the wound electrode body abnormally generated heat due to overcharging, the timing of closing the holes could be aligned in the radial direction. Therefore, it is considered that the battery reaction does not suddenly occur as described above (leakage current hardly flows). Moreover, it is thought that it was able to appropriately suppress the wound electrode body from further generating heat and becoming high temperature.

Next, as Example 4, a negative electrode plate 41 was manufactured in the same manner as Example 1 (Embodiment 1). That is, the insulating paste layer 51 p was applied on the negative electrode plate 41 using the gravure coating apparatus 100. The outer peripheral surface 110a of the gravure roll 110 of the gravure coating apparatus 100 has a concavo-convex pattern 111 in which the amount of the insulating paste ZP to be held gradually decreases as it advances from one side SA in the circumferential direction SH to the other side SB. Specifically, as the capacity of the cell 112 per unit area of the outer peripheral surface 110a proceeds from one side SA in the circumferential direction SH to the other side SB, the maximum (100 cm ³ / m ² ) to the minimum (90 cm ³ / m ^2). ) Is gradually reduced until. By using such a gravure roll 110, as described above, the thickness t is thicker at a portion located on one side NA of the negative electrode plate 41 (30 μm at the innermost side) and thinner at a portion located on the other side NB ( Separator layer 51 was able to be formed.

On the other hand, in Comparative Example 2, the concavo-convex pattern on the outer peripheral surface of the gravure roll has a form in which the amount of the insulating paste ZP held on the outer peripheral surface is constant over the entire circumferential direction SH. Specifically, the volume of each cell was made equal, and the volume of the cell per unit area was made equal to 90 cm ³ / m ² over the entire outer peripheral surface. As a result of using this gravure roll, the thickness t of the separator layer became a constant thickness (specifically 25 μm) regardless of the location in the longitudinal direction NY of the negative electrode plate. The battery according to Comparative Example 1 described above is manufactured using this negative electrode plate.

  Next, as Example 5, a negative electrode plate 41 was manufactured in the same manner as in Embodiment 2. That is, the insulating paste ZP was applied on the negative electrode plate 41 using the gravure coating apparatus 200. Specifically, the concavo-convex pattern 211 on the outer peripheral surface 210a has a configuration in which a large number of concave grooves 212 extending obliquely with respect to the circumferential direction SH of the gravure roll 210 (intersecting at θ = 45 °) are arranged (Table 3). In the “concave / convex pattern” in FIG. The capacity of the concave groove 212 per unit area of the outer peripheral surface 210a is constant regardless of the location. Further, the hydraulic pressure Pz applied to the insulating paste ZP by the pump 245 was gradually decreased from a maximum of 3.2 kPa to a minimum of 2.1 kPa, and the amount of the insulating paste ZP held on the outer peripheral surface 210a was gradually decreased. Thereby, as described above, the thickness t is thicker at the portion located on the one side NA of the negative electrode plate 41 (30 μm at the innermost side) and thinner at the portion located at the other side NB (25 μm at the outermost side). Could be formed.

Further, as Example 6, the concave-convex pattern of the gravure roll is arranged with a large number of concave grooves extending obliquely (intersecting at θ = 45 °) with respect to the circumferential direction SH of the gravure roll, and these concave grooves And a plurality of concave grooves extending at an angle with respect to the circumferential direction SH of the gravure roll (intersecting at θ = 45 °) are arranged at regular intervals (in the “concavo-convex pattern” in Table 3, “ Indicated as "reciprocal lattice"). The capacity of the groove per unit area of the outer peripheral surface is
It is 81.2 cm ³ / m ² which is constant regardless of the place. Further, the hydraulic pressure Pz applied to the insulating paste ZP by the pump was gradually decreased from the maximum 3.1 kPa to the minimum 2.1 kPa, and the amount of the insulating paste ZP retained on the outer peripheral surface was gradually decreased. Otherwise, it was the same as Example 5. As a result, it was possible to form a separator layer having a thickness t that is thicker at a portion located on one side NA of the negative electrode plate 41 (29 μm at the innermost side) and thinner at a portion located at the other side NB (25 μm at the outermost side).

  On the other hand, in the comparative example 3, the gravure coating apparatus 200 of the second embodiment is used. However, the hydraulic pressure Pz applied to the insulating paste ZP is kept constant (Pz = 2.1 kPa) with the pump 245, and the insulating paste ZP is applied to the negative electrode plate 41. It was applied on top. In this case, since the insulating paste ZP retained on the outer peripheral surface 210a after being scraped off by the doctor blade 220 is constant, the thickness of the insulating paste layer is also constant regardless of the location in the longitudinal direction NY of the negative electrode plate 41. . Therefore, the thickness t of the separator layer was only a constant thickness (specifically 25 μm) regardless of the location in the longitudinal direction NY of the negative electrode plate 41.

Moreover, in Comparative Example 4, the uneven pattern of the gravure roll was a pattern in which a large number of cells each having a concave portion having a rectangular shape in plan view were arranged in a grid pattern (in the “uneven pattern” in Table 3, “lattice pattern” is shown). ). The capacity of the cell per unit area on the outer peripheral surface is 70.1 cm ³ / m ² constant regardless of the location. Further, the hydraulic pressure Pz applied to the insulating paste ZP by the pump was gradually decreased from a maximum of 3.1 kPa to a minimum of 2.0 kPa. Otherwise, it was the same as Example 5.

  In the case of this comparative example 4, even if the hydraulic pressure Pz is applied to the insulating paste ZP stored between the gravure roll and the doctor blade by the pump, the insulating paste ZP held in each independent cell moves in the circumferential direction SH. Can not. For this reason, the insulating paste ZP is not pushed out to the outer peripheral surface of the rotation direction side RA of the gravure roll rather than the doctor blade. Therefore, even if the hydraulic pressure Pz is increased or decreased, the amount of the insulating paste ZP transferred onto the negative electrode plate 41 is constant, and the thickness of the insulating paste layer is also constant in the longitudinal direction NY of the negative electrode plate 41 regardless of the location. . As a result, the thickness t of the separator layer was only substantially constant (specifically, 24 to 25 μm) regardless of the location in the longitudinal direction NY of the negative electrode plate 41.

In the above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist thereof.
For example, in the first and second embodiments, the cylindrical wound electrode body 30 is exemplified as the wound electrode body. However, the present invention is not limited to this, and for example, a flat wound electrode body may be used. That is, as a wound electrode body in which a belt-like positive electrode plate and a belt-like negative electrode plate are alternately overlapped with each other via two separators made of a belt-like porous thermoplastic resin, and wound in a flat shape around an axis. Also good.

  For example, in the first embodiment, the uneven pattern 111 of the gravure roll 110 is configured such that the amount of the insulating paste ZP held on the outer peripheral surface 110a decreases as it advances from the one side SA in the circumferential direction SH to the other side SB. However, conversely, the concavo-convex pattern may be formed in a form in which the amount of the insulating paste ZP held on the outer peripheral surface increases as it proceeds from the one side SA in the circumferential direction SH to the other side SB. In this case, in the coating process, the insulating paste layer is formed so as to increase in thickness as it proceeds from one side NA in the longitudinal direction NY of the negative electrode plate 41 to the other side NB. And the separator layer whose thickness t becomes thick is formed as it progresses from the one side NA of the longitudinal direction NY of the negative electrode plate 41 to the other side NB. Even when such a negative electrode plate having a separator layer is used, it is possible to form a wound electrode body in which the separator layer is thicker in the radially inner VA region and the separator layer is thinner in the radially outer VB region.

  In the coating process of the second embodiment, the hydraulic pressure Pz applied to the insulating paste ZP stored between the gravure roll 210 and the doctor blade 220 by the pump 245 is gradually lowered and scraped off by the doctor blade 220. After that, the amount of the insulating paste ZP held on the outer peripheral surface 210a was gradually reduced. However, conversely, the hydraulic pressure Pz applied to the insulating paste ZP may be gradually increased to gradually increase the amount of the insulating paste ZP held on the outer peripheral surface 210a. In this case, the insulating paste layer is formed in a form that becomes thicker from the one side NA in the longitudinal direction NY of the negative electrode plate 41 to the other side NB. And the separator layer whose thickness t becomes thick is formed as it progresses from the one side NA of the longitudinal direction NY of the negative electrode plate 41 to the other side NB. Even when such a negative electrode plate having a separator layer is used, it is possible to form a wound electrode body in which the separator layer is thicker in the radially inner VA region and the separator layer is thinner in the radially outer VB region.

10 Battery 30 Winding type electrode body 31 Positive electrode plate 41 Negative electrode plate (electrode plate to be coated)
41a, 41b (negative electrode plate) main surface 51 Separator layer (separator)
51p Insulating paste layer 100, 200 Gravure coating device 110, 210 Gravure roll 110a, 210a Peripheral surface 111, 211 (outer surface) uneven pattern 112 Cell 212 Concave groove 120, 220 Doctor blade 130, 230 Liquid Tank 245 Pump 250 Pressure gauge AX Winding axis VY (of wound electrode body) Radial direction VA (of wound electrode body) Radial inner side VB (of wound electrode body) Radially outer side NY (of negative electrode plate) longitudinal direction NA (of negative electrode plate) longitudinal inner side direction (one side)
NB Longitudinal direction (the other side) of the negative electrode plate
TY (negative electrode plate) thickness direction t (separator layer) thickness t1 (separator layer end in the longitudinal inner direction) thickness t2 (separator layer end in the longitudinal outer direction) thickness ZP insulating paste La (negative electrode plate longitudinal) Dimension Lb (in the direction of gravure roll) SH (in the direction of gravure roll) circumferential direction SA (in the direction of gravure roll) One side SB (in the circumferential direction) SB (in the circumferential direction) WH in the width direction RA (in the direction of gravure roll)

Claims (6)

A battery comprising a wound electrode body in which a belt-like positive electrode plate and a belt-like negative electrode plate are alternately overlapped and wound via two separators made of a belt-like porous thermoplastic resin,
Each of the separators is a battery that is thicker at a portion located on the radially inner side of the wound electrode body and thinner at a portion located on the radially outer side. The battery according to claim 1,
The separator is
Each battery is a separator layer coated and formed on the main surface of an electrode plate to be applied, which is at least one of the positive electrode plate and the negative electrode plate. A wound electrode body comprising a belt-like positive electrode plate and a belt-like negative electrode plate, which are wound in an alternating manner through two separators made of a belt-like porous thermoplastic resin,
Each of the separators is a battery manufacturing method in which the portion located on the radially inner side of the wound electrode body is thicker and the portion located on the radially outer side is thinner,
Using a gravure coating apparatus equipped with a gravure roll, an insulating paste in which thermoplastic resin particles are dispersed in a solvent is applied on the main surface of at least one of the positive electrode plate and the negative electrode plate, A coating process for forming an insulating paste layer;
Drying the insulating paste layer to form a separator layer that is the separator, and
The gravure roll is
The outer peripheral length has a dimension greater than or equal to the longitudinal dimension of the coated electrode plate,
The outer peripheral surface has an amount of the insulating paste held on the outer peripheral surface as it proceeds from one side to the other side in the circumferential direction of the gravure roll at least in the range of the dimension in the longitudinal direction of the electrode plate to be coated. Have more or less uneven patterns,
The coating process includes
A method for producing a battery, which is a step of forming the insulating paste layer in a form in which the thickness of the insulating paste layer is increased or decreased from one side in the longitudinal direction of the coated electrode plate to the other side by the gravure roll. . A method of manufacturing a battery according to claim 3,
The uneven pattern on the outer peripheral surface is:
A battery manufacturing method comprising a large number of cells independent from each other, wherein the capacity of the cell per unit area of the outer peripheral surface increases or decreases from one side to the other side in the circumferential direction of the gravure roll . A method of manufacturing a battery according to claim 3 or claim 4,
The method for manufacturing a battery, wherein the uneven pattern on the outer peripheral surface is formed by laser engraving. A wound electrode body comprising a belt-like positive electrode plate and a belt-like negative electrode plate, which are wound in an alternating manner through two separators made of a belt-like porous thermoplastic resin,
Each of the separators is a battery manufacturing method in which the portion located on the radially inner side of the wound electrode body is thicker and the portion located on the radially outer side is thinner,
Using a gravure coating apparatus equipped with a gravure roll, an insulating paste in which thermoplastic resin particles are dispersed in a solvent is applied on the main surface of at least one of the positive electrode plate and the negative electrode plate, A coating process for forming an insulating paste layer;
Drying the insulating paste layer to form a separator layer that is the separator, and
The gravure roll has a concavo-convex pattern in which a large number of concave grooves extending at least in the circumferential direction among the width direction and the circumferential direction of the gravure roll are arranged at regular intervals on the outer peripheral surface thereof,
The gravure coating apparatus is
A doctor blade that scrapes off the insulating paste on the outer peripheral surface;
A pump for changing a hydraulic pressure applied to the insulating paste stored between the gravure roll and the doctor blade,
The coating process includes
Changing the hydraulic pressure with the pump, increasing or decreasing the amount of the insulating paste retained on the outer peripheral surface after being scraped with the doctor blade,
A method for manufacturing a battery, which is a step of forming the insulating paste layer in a form in which the thickness of the insulating paste layer becomes thicker or thinner as it proceeds from one side in the longitudinal direction of the coated electrode plate to the other side.

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