JP5817571B2 - Method for manufacturing bag-shaped separator for power storage device - Google Patents

Description

The present invention relates to the production how the bag-like separator for a power storage device that houses the electrode sheet.

  Conventionally, lithium-ion secondary batteries and nickel-hydrogen secondary batteries are well known as power storage devices mounted on vehicles and the like. For example, in a lithium ion secondary battery, an electrode body in which an electrode sheet has a laminated structure is housed in a case.

  In such an electrode body, electrode sheets are prevented from contacting each other by inserting a sheet-like separator including a porous film having a fine pore structure between the electrode sheets. In addition, when the temperature of the electrode body reaches a predetermined temperature (hereinafter referred to as “cutoff temperature”), the separator melts part of the porous film and collapses the pore structure, and the current between the electrode sheets is reduced. It is designed to shut off.

  As such a separator, a separator whose surface is covered with a porous coat layer containing ceramic particles (powder) such as alumina has been proposed (for example, Patent Document 1). According to the separator of Patent Document 1, even when the temperature of the electrode body further rises above the cutoff temperature of the separator, the entire separator contracts or opens a hole due to the coating layer containing ceramic particles. This suppresses short-circuiting between the electrode sheets.

JP 2000-30686 A

  By the way, in the separator as described above, from the viewpoint of preventing contact between the electrode sheets, the flat surfaces of the separator are joined together by heat welding or adhesion to form a bag shape. However, since the surface of the separator of Patent Document 1 is covered with the coating layer, it is difficult to join the flat surfaces of the separator itself, and the strength at the joint may be reduced.

This invention was made paying attention to the problem which exists in the said prior art, The objective is the intensity | strength in a junction part, suppressing that the electrode sheets which comprise an electrode body short-circuit at high temperature. there is to provide a manufacturing how the bag-like separator for a power storage device capable of suppressing a decrease.

In order to solve the above-mentioned problem, the invention according to claim 1 is a method for manufacturing a bag-like separator for a power storage device that accommodates an electrode sheet, wherein the planes of the separator are joined together to form a bag-like separator. The gist is to include a forming step and a coating step of forming a porous coating layer containing ceramic particles on the inner surface of the bag-like separator after the forming step.

According to this, before forming a coat layer, planes of a separator are joined together and formed in a bag shape. For this reason, it can suppress that the plane of a separator joins in the state where a coat layer and a part of component of a coat layer do not exist, and the intensity of the joined part in a bag-like separator falls. And it can suppress that a bag-shaped separator shrink | contracts or a hole opens under high temperature by forming the coat layer containing a ceramic particle in the inner surface of the bag-shaped separator obtained by the formation process. Therefore, it can suppress that the intensity | strength in a junction part falls, suppressing that the electrode sheets which comprise an electrode body short circuit at high temperature.

  The gist of the invention described in claim 2 is that, in the method of manufacturing the bag-shaped separator for the power storage device according to claim 1, in the forming step, the planes of the separator are joined to each other by thermal welding.

  According to this, even in the case where the planes of the separators are joined together by thermal welding to form a bag-like separator, the coating layer is formed after the bag-like formation, so that the strength at the joint is high. It can suppress suitably that it falls.

  According to a third aspect of the present invention, in the method for manufacturing a bag-shaped separator for a power storage device according to the first or second aspect, in the coating step, the coating layer is formed on both the outer surface and the inner surface of the bag-shaped separator. The gist is to do.

According to this, since the coat layers are formed on both the outer surface and the inner surface of the bag-like separator, it is possible to further suppress short-circuiting between the electrode sheets constituting the electrode body at a high temperature.
Invention of Claim 4 WHEREIN: In the manufacturing method of the bag-shaped separator of any one of Claims 1-3, in the said formation process, joining the edge parts among the planes of the said separator, In at least one side of the bag-shaped separator, end faces in the surface direction of the separator are adjacent to each other, and in the coating step, the coating layer is formed on at least a part of the end surfaces of the separator adjacent to each other in the forming step. And

  According to this, in the coating process, since the coating layer is formed on at least a part of the end faces of the separators that are adjacent to each other in the forming process, the area where the end faces of the separator are exposed in the bag-like separator can be reduced. For this reason, the shrinkage | contraction of the separator in the end surface of a separator can be suppressed suitably.

  According to a fifth aspect of the present invention, in the method of manufacturing a bag-shaped separator for a power storage device according to the fourth aspect, in the coating step, the coating layer is applied to the entire end face of the separator that is adjacent in the forming step. The gist is to form.

  According to this, since the coat layer is formed on the entire end faces of the separators adjacent to each other in the forming step, the region where the end faces of the separators are exposed can be further reduced, and the shrinkage of the separators on the end faces of the separators can be further suppressed.

Invention of Claim 6 is a manufacturing method of the bag-shaped separator for electrical storage devices given in any 1 paragraph of Claims 1-5, and the opening where the edges of the separator are not joined in the formation process. The bag-shaped separator is formed so as to have a portion, and the coating step is to form the coating layer on the end face of the separator disposed around the opening .

According to this, in the coating process, the shrinkage of the separator on the end face of the separator disposed around the opening can be further suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that the intensity | strength in a junction part falls, suppressing that the electrode sheets which comprise an electrode body short circuit at high temperature.

The perspective view which shows a secondary battery typically. (A) is a perspective view schematically showing the disassembled electrode body, (b) is a perspective view showing a state where the bag-like separator is cut along the line AA shown in (a), and (c) is ( The perspective view which shows the state which cut | disconnected the bag-shaped separator by the BB line shown to a). (A) is a front view which shows a negative electrode sheet typically, (b) is a front view which shows a positive electrode sheet typically. The flowchart which shows the manufacturing method (manufacturing procedure) of a secondary battery and a bag-shaped separator. (A)-(d) is a schematic diagram for demonstrating the manufacturing method of a bag-shaped separator. The schematic diagram for demonstrating the manufacturing method of the bag-shaped separator in another embodiment.

Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS.
As shown in FIG. 1, a secondary battery 10 as a power storage device mounted on a vehicle (for example, an industrial vehicle or a passenger vehicle) includes a case 11 having a flat and substantially rectangular parallelepiped shape as a whole. The case 11 has a flat plate shape (this embodiment) assembled to the main body member 12 so as to seal the main body member 12 formed in a bottomed cylindrical shape (square tube shape in the present embodiment) and the opening 12a of the main body member 12. It is formed from a lid member 13 having a rectangular flat plate shape. The main body member 12 and the lid member 13 are both made of metal (for example, stainless steel or aluminum). In the following description, the longitudinal direction of the case 11 indicated by the arrow Y1 is indicated as the left-right direction, the height direction of the case 11 indicated by the arrow Y2 is indicated as the vertical direction, and the short direction of the case 11 indicated by the arrow Y3 in FIG. This is indicated as the front-rear direction.

  On the outer surface (upper surface) of the lid member 13, a positive electrode terminal 15 and a negative electrode terminal 16 having a cylindrical shape (substantially cylindrical shape) are formed to protrude. The positive electrode terminal 15 and the negative electrode terminal 16 are insulated from the case 11 (the main body member 12 and the lid member 13).

  The case 11 (main body member 12) accommodates (contains) an electrode body 25 in which a positive electrode sheet 21 as an electrode sheet and a negative electrode sheet 22 as an electrode sheet form a layered structure (laminated structure). The electrode body 25 has a rectangular parallelepiped shape (substantially rectangular parallelepiped shape) that is flat in the left-right direction as a whole. In addition, the electrode body 25 is accommodated in the case 11 in a state of being covered with an insulating bag (not shown) made of an insulating material. The case 11 is filled with an electrolyte (electrolyte) according to the type of the secondary battery 10 such as a lithium ion secondary battery or a nickel hydride secondary battery.

  As shown in FIG. 2A, the positive electrode sheet 21 and the negative electrode sheet 22 are provided with a metal foil 26 having a rectangular sheet shape. The thickness of the metal foil 26 is, for example, 10 μm or more and 50 μm or less, and preferably 15 μm or more and 25 μm or less. The metal foil 26 is formed of a metal corresponding to the type of the secondary battery 10 such as a lithium ion secondary battery or a nickel hydride secondary battery. The metal used for the metal foil 26 is different between the positive electrode sheet 21 and the negative electrode sheet 22. The metal foil 26 of the positive electrode sheet 21 is made of, for example, aluminum, and the metal foil 26 of the negative electrode sheet 22 is made of, for example, copper.

  On both surfaces (front surface and rear surface) of each metal foil 26, the non-formation region (uncoated portion) 26 b set with a constant width from the upper side 26 a of each metal foil 26 to the entire width in the left-right direction is applied to the entire surface. A material is applied to form an active material layer 27. Note that an active material corresponding to the type of the secondary battery 10 is applied to the metal foil 26. The active material applied to the metal foil 26 is different between the positive electrode sheet 21 and the negative electrode sheet 22.

  Further, on the left side of the upper side 26a in each positive electrode sheet 21, a non-formation region 26b is punched and formed into a rectangular (substantially rectangular) positive electrode lead 21a extending upward (the lid member 13). On the right side of the upper side 26a of each negative electrode sheet 22, a negative electrode lead 22a having a rectangular shape (substantially rectangular shape) is formed by extending the non-formed region 26b so as to extend upward (the cover member 13). For this reason, the active material layer 27 is not formed on the surfaces of the positive electrode lead 21a and the negative electrode lead 22a.

In the electrode body 25, each positive electrode sheet 21 is accommodated (inserted) in a bag-shaped separator 29 including a separator 28.
As shown in FIG. 2B and FIG. 2C, the separator 28 is made of polyethylene on both sides of the base material layer 28a that forms a porous sheet made of polypropylene, and is finer than the base material layer 28a. It has a three-layer structure in which a pore layer 28b having a porous sheet shape having pore structure (pores) is formed.

  When the separator 28 reaches the melting point (for example, 135 ° C. to 140 ° C.) of the resin material (polyethylene) constituting the pore layer 28b, the pore layer 28b melts, the pore structure collapses, and the pores are blocked. Can be removed. Thereby, the current (ion passage) between the positive electrode sheet 21 and the negative electrode sheet 22 is interrupted (so-called shutdown function). In the following description, the temperature at which the pore structure of the pore layer 28b collapses is simply referred to as “cutoff temperature”. Further, the melting point of the resin material (polypropylene) constituting the base material layer 28a is higher than the melting point (blocking temperature) of the resin material (polyethylene) constituting the pore layer 28b, for example, 165 ° C. or higher.

  The bag-like separator 29 is formed in a bag shape by folding the separator 28 having a rectangular sheet shape in the longitudinal direction and joining the opposed planes together by thermal welding. Specifically, as shown by hatching in FIG. 2 (a), the bag-like separator 29 has pore layers 28b arranged opposite to each other at both edges in the short direction (left-right direction) of the separator 28. Are joined directly by thermal welding over the entire length of the separator 28 in the longitudinal direction (vertical direction), thereby forming a joining portion 29a in which the pore layers 28b (planes) are joined together.

  Therefore, in the bag-shaped separator 29 of the present embodiment, the edges of the plane (the pore layer 28 b) of the separator 28 are joined to each other, and the two sides of the bag-shaped separator 29 are arranged in the left-right direction. At both edges, end faces 28c in the surface direction of the separator 28 are adjacent to each other. That is, the end face 28c and the end face 28c of the separator 28 are arranged in parallel so as to be adjacent to each other and parallel to each other at the both edges in the left-right direction of the bag-like separator 29. In the bag-like separator 29 of the present embodiment, the end face 28 c of the separator 28 is also arranged around the opening of the bag-like separator 29.

  Further, as shown in FIGS. 2 (a) to 2 (c), both the inner surface and the outer surface of the bag-shaped separator 29 are made of a porous material containing ceramic particles (ceramic powder) and a resin material serving as a binder. Each coat layer 29b is formed. The coat layer 29b of the present embodiment is formed over the entire inner surface and outer surface of the bag-shaped separator 29. The pore layer 28b of the separator 28 described above does not contain ceramic particles. Further, in the joint portion 29a, the coat layer 29b is not interposed between the pore layer 28b and the pore layer 28b (between the separator 28 and the separator 28).

  Further, as shown in FIG. 2B, a coat layer 29b is formed over the entire surface (entire surface) on the end surface 28c, which is the upper end surface of the separator 28 disposed around the opening of the bag-shaped separator 29. At the same time, the end face 28c is entirely covered with the coat layer 29b. Further, as shown in FIG. 2C, a coat layer 29b is formed on the whole (entire surface) of the end face 28c and the end face 28c of the separator 28 adjacent to each other in the left and right edges of the bag-like separator 29. The end face 28c and the end face 28c are entirely covered with the coat layer 29b. Therefore, in the bag-like separator 29 of the present embodiment, the coat layer 29b is formed on all the end faces 28c of the separator 28 forming the bag-like separator 29, and is covered with the coat layer 29b.

Here, the resin material (binder) forming the coat layer 29b is a para-oriented aromatic polyamide (para-aramid) resin which is a kind of heat-resistant resin material. The ceramic particles contained in the coat layer 29b are aluminum oxide (Al ₂ O ₃ ). The average particle size of the ceramic particles is, for example, 1.0 μm or less, preferably 0.5 μm or less. Here, the “average particle diameter” in the present specification means an average particle diameter observed with a scanning electron microscope (SEM).

  Further, the content of the ceramic particles in the coat layer 29b is, for example, 1 wt% or more and 95 wt% or less, preferably 5 wt% or more and 50 wt% or less of the weight of the bag-shaped separator 29. For this reason, the coating layer 29b does not significantly contract (deform) even when the temperature exceeds the cutoff temperature of the pore layer 28b and further reaches the melting point of the resin material constituting the base material layer 28a. The softened separator 28 is held to maintain the shape.

  As shown in FIGS. 3A and 3B, the left-right direction length L 1 of the negative electrode sheet 22 is the same (substantially the same) as the left-right direction length L 2 of the bag-shaped separator 29. The vertical length L3 of the negative electrode sheet 22 is slightly smaller than the vertical length L4 of the bag-shaped separator 29. The positive electrode sheet 21 is formed smaller than the negative electrode sheet 22 and the bag-shaped separator 29 in a front view.

  Further, in a state where the positive electrode sheet 21 is accommodated in the bag-shaped separator 29, the length L6 from the lower end of the bag-shaped separator 29 to the boundary between the active material layer 27 and the non-formation region 26b in the positive electrode sheet 21 is It is smaller than the length L5 from the lower end to the boundary between the active material layer 27 and the non-formation region 26b. In this state, the lower end of the positive electrode sheet 21 is separated from the bottom of the bag-shaped separator 29.

  For this reason, when the negative electrode sheet 22 and the bag-shaped separator 29 containing the positive electrode sheet 21 are stacked in a state where both ends and the lower end in the left-right direction match in front view, The formation region of the active material layer 27 is included in the formation region of the active material layer 27 in the negative electrode sheet 22.

  As shown in FIG. 2A, the electrode body 25 includes a bag-like separator 29 containing the positive electrode sheet 21 (a positive electrode sheet 21 contained in the bag-like separator 29) and a negative electrode sheet 22 in the thickness direction (front and rear). Direction). Specifically, in the electrode body 25, the plurality of bag-like separators 29 containing the positive electrode sheet 21 and the plurality of negative electrode sheets 22 are: →→ bag-like separator 29 containing the positive electrode sheet 21 → negative electrode sheet 22 → positive electrode sheet 21. Are alternately arranged like bag-like separators 29. Of the positive electrode sheet 21 and the negative electrode sheet 22 constituting the electrode body 25, the electrode sheets disposed at both ends in the stacking direction are both negative electrode sheets 22. In addition, separators 28 each having a rectangular sheet shape are disposed at both ends of the electrode body 25 in the stacking direction.

  Thus, as shown in FIG. 1, on the left side of the upper side 26a of the electrode body 25, a plurality of positive electrode leads 21a form a layer (laminated structure) with no separator 28 (bag-shaped separator 29) sandwiched therebetween. A current collector 30 is formed extending upward. Also, on the right side of the upper side 26a of the electrode body 25, a negative electrode current collector 31 is formed that has a layered structure (laminated structure) with a plurality of negative electrode leads 22a sandwiching no separator 28 (bag-shaped separator 29) therebetween. Yes.

  The positive electrode current collector 30 (positive electrode lead 21 a) and the positive electrode terminal 15 described above are electrically connected by a positive electrode current collector terminal 33. Further, the negative electrode current collector 31 (negative electrode lead 22 a) and the negative electrode terminal 16 are electrically connected by a negative electrode current collector terminal 34.

Next, the manufacturing method of the secondary battery 10 and the bag-like separator 29 will be described with reference to FIGS. 4 and 5 together with the operation thereof.
As shown in FIG. 4, a thermal welding process is performed as a forming process for joining the flat surfaces (pore layer 28 b) of the separator 28 to form the bag-shaped separator 29 (step S <b> 1). As shown in FIGS. 5A and 5B, the rectangular separator 28 is folded in half in the longitudinal direction so that the planes (pore layers 28b) face each other. Next, as shown in FIG. 5 (c), both edges in the short direction (left and right direction) of the separator 28 are heat-welded and joined over the entire length of the separator 28 so that the separator 28 has a bag shape. An eggplant-shaped separator 29 is obtained. In this state, the coat layer 29 b is not formed on the outer and inner surfaces of the bag-like separator 29. In this heat welding step, the left and right edges of the plane (pore layer 28b) of the separator 28 are joined (heat welded) to each other in the left and right edges (two sides) of the bag-like separator 29. The end faces 28c of the separators 28 are adjacent to each other.

  Next, as shown in FIG. 4, a coating process is performed as a coating process for forming the coating layer 29b on both the outer and inner surfaces of the bag-shaped separator 29 (step S2). In this coating step, first, ceramic particles are added to a solvent (such as a polar organic solvent) containing para-oriented aromatic polyamide to prepare a coating agent. Next, as shown in FIG. 5 (d), the bag-like separator 29 obtained in the heat welding step is dipped in the prepared coating agent and applied to both the outer and inner surfaces of the bag-like separator 29. A coating agent is applied to form a coat layer 29b. At this time, in the coating process, the coating agent is applied to all of the end faces 28c of the separator 28 including the end faces 28c of the separator 28 that are adjacent to each other in the heat welding process, and the coating layer 29b is formed. Form.

  Next, as shown in FIG. 4, a drying process for drying the coat layer 29b formed on the bag-like separator 29 is performed (step S3). By this drying step, the solvent is removed from the coat layer 29b, and the para-oriented aromatic polyamide is deposited to complete the porous coat layer 29b. Thus, the bag-like separator 29 of this embodiment is completed.

  Thus, in this embodiment, before forming the coat layer 29b, the planes (pore layers 28b) of the separator 28 are joined (thermally welded) to form a bag shape. For this reason, it can suppress that the planes of the separator 28 are joined in the state which the coating layer 29b does not interpose, and the intensity | strength of the junction part 29a in the bag-shaped separator 29 falls. That is, when it is going to join the planes of the separator 28 in which the coat layer 29b is formed in advance, it is difficult to join the separator 28 itself, and the strength (joining strength) at the joint portion 29a may be reduced. There is. In this embodiment, such a problem is suitably solved by performing a coating process after a heat welding process.

  In the present embodiment, since the coating layer 29b is formed on both the outer surface and the inner surface of the bag-shaped separator 29 in the coating process, the separator 28 is separated by the coating layer 29b even at a high temperature exceeding the cutoff temperature. Thus, it is possible to prevent the separator 28 from contracting or opening a hole.

  Further, in the coating process of the present embodiment, the coat layer 29b is formed on the entire end face 28c (entire surface) of the separator 28 adjacent to each other in the heat welding process. For this reason, in the bag-shaped separator 29, the area | region where the end surface 28c of the separator 28 is exposed can be made small. For this reason, the shrinkage | contraction in the end surface 28c of the separator 28 can be suppressed suitably under the high temperature which exceeds interruption | blocking temperature.

  In particular, in the present embodiment, in the coating process, the coat layer 29b is formed on all the end faces 28c of the separator 28 that forms the bag-shaped separator 29. For this reason, the shrinkage | contraction in the end surface 28c of the separator 28 can be suppressed more suitably. In the coating process, since the bag-shaped separator 29 is immersed in the coating agent, the coat layer 29 b can be easily formed on the outer and inner surfaces of the bag-shaped separator 29 and the end surface 28 c of the separator 28.

  Next, as shown in FIG. 4, an insertion process is performed as an accommodation process for inserting (accommodating) the positive electrode sheet 21 obtained in a separate process into the bag-shaped separator 29 (step S <b> 4). Subsequently, a laminating process is performed in which the bag-like separator 29 containing the positive electrode sheet 21 and the negative electrode sheet 22 obtained in a separate process are alternately laminated to form the electrode body 25 (step S5).

  Next, an assembly process is performed in which the electrode body 25 is accommodated in the case 11 and assembled (step S6). More specifically, in this assembly step, the positive electrode current collector terminal 33 is joined to the positive electrode current collector 30 (positive electrode lead 21a) of the electrode body 25, and the positive electrode terminal 15 is electrically connected to the positive electrode current collector terminal 33. To do. In the assembling step, the negative electrode current collector terminal 34 is joined to the negative electrode current collector 31 (negative electrode lead 22 a) of the electrode body 25, and the negative electrode terminal 16 is electrically connected to the negative electrode current collector terminal 34. In the assembling step, the electrode body 25 is housed in the main body member 12, and the lid member 13 is assembled to the main body member 12 while the positive electrode terminal 15 and the negative electrode terminal 16 are projected from the upper surface. Next, a filling step for filling the case 11 with an electrolyte (electrolytic solution) is performed (step S7). Thus, the secondary battery 10 is completed.

Therefore, according to the present embodiment, the following effects can be obtained.
(1) Before forming the coat layer 29b, the planes of the separators 28 (pore layers 28b) are joined to form a bag. For this reason, it can suppress that the planes of the separator 28 are joined in the state which the coating layer 29b does not interpose, and the intensity | strength of the junction part 29a in the bag-shaped separator 29 falls. And by forming the coating layer 29b containing ceramic particles on both the outer surface and the inner surface of the bag-shaped separator 29 obtained by the heat welding process, the bag-shaped separator 29 contracts or opens a hole at a high temperature. Can be suppressed. Therefore, it is possible to suppress a decrease in strength at the joint portion 29a while suppressing a short circuit between the positive electrode sheet 21 and the negative electrode sheet 22 constituting the electrode body 25 at a high temperature.

  (2) Even in the case where the planes of the separators 28 (the pore layers 28b) are joined by heat welding to form the bag-like separator 29 simply, the coat layer 29b is formed after forming the bag-like shape. Since it forms, it can suppress suitably that the intensity | strength in the junction part 29a falls.

  (3) Since the coat layers 29b are formed on both the outer surface and the inner surface of the bag-shaped separator 29, it is possible to further suppress the short-circuit between the positive electrode sheet 21 and the negative electrode sheet 22 constituting the electrode body 25 at a high temperature.

  (4) In the coating process, since the coat layer 29b is formed on the entire end face 28c of the separator 28 adjacent to each other in the heat welding process, the separator 28 is further formed compared to the case where the coat layer 29b is formed on a part thereof. A region (area) where the end face 28 c is exposed can be reduced, and the shrinkage of the separator 28 on the end face 28 c of the separator 28 can be further suppressed.

  (5) In the coating process, since the coat layer 29b is formed on the entire end face 28c of the separator 28, the region where the end face 28c of the separator 28 is exposed is eliminated, and the separator 28 contracts at the end face 28c of the separator 28. Further suppression can be achieved.

  (6) According to the bag-like separator 29 obtained by the manufacturing method of the present embodiment, the junction portion is suppressed while the positive electrode sheet 21 and the negative electrode sheet 22 constituting the electrode body 25 are short-circuited at a high temperature. It can suppress that the intensity | strength in 29a falls.

  (7) Since the positive electrode sheet 21 is accommodated in the bag-shaped separator 29, as the secondary battery 10, the positive electrode sheet 21 and the negative electrode sheet 22 constituting the electrode body 25 are prevented from being short-circuited at a high temperature. It is possible to suppress the strength at the joint portion 29a from being lowered.

  (8) In the stacking step, the bag-shaped separator 29 containing the positive electrode sheet 21 and the negative electrode sheet 22 are stacked to form the electrode body 25. For this reason, compared with the case where the electrode body 25 is formed while sandwiching the sheet-like separator 28 between the positive electrode sheet 21 and the negative electrode sheet 22, the electrode body 25 can be easily formed. The active material layer 27 forming region in the positive electrode sheet 21 protrudes from the active material layer 27 forming region in the negative electrode sheet 22 in a direction (plane direction) perpendicular to the stacking direction of the positive electrode sheet 21 and the negative electrode sheet 22. It can suppress suitably that it laminates | stacks.

The embodiment is not limited as described above, and may be embodied as follows, for example.
As shown in FIG. 6, the separator 28 having a long sheet shape (band shape) is folded in half in the width direction and continuously (connected) by joining over the entire width at constant intervals by heat welding. ) A plurality of bag-like separators 29 may be formed. In this case, the continuous bag-shaped separator 29 is immersed in the coating agent and dried, and then cut in the width direction at the joint portion 29a (shown by a dotted line). According to this, the bag-shaped separator 29 can be manufactured easily.

  ○ The bag-shaped separator 29 is formed by bending the separator 28 having a long sheet shape (band shape) into a bellows shape and joining both edges in the short direction of the separator 28 to form the positive electrode sheet 21 and the negative electrode sheet 22. You may form the some accommodating part to accommodate.

The bag-shaped separator 29 may be formed by joining two separators 28.
(Circle) the separator 28 does not include the base material layer 28a, and may be formed from the single | mono layer or the multilayer porous layer 28b.

The bag-like separator 29 may be formed by joining the planes (pore layers 28b) of the separator 28 by ultrasonic welding or adhesion using an adhesive.
The bag-like separator 29 may be joined at a plurality of locations intermittently in the longitudinal direction of the separator 28 at both edges in the lateral direction of the separator 28 or may be joined at one location.

The resin material forming the coat layer 29b may be changed to another kind of heat resistant resin such as polyimide resin or acrylate resin.
The ceramic particles contained in the coat layer 29b may be changed to, for example, silica (SiO ₂ ), titanium dioxide (TiO ₂ ), and zirconium oxide (ZrO ₂ ), and include two or more kinds of ceramic particles. May be.

  As long as it is stable to the electrolyte and does not impair the above-described shutdown function, the type of the resin material constituting the separator 28 (base material layer 28a and pore layer 28b) may be changed.

The coat layer 29b may include ceramic particles having different average particle diameters.
In the heat welding step, the end face 28c of the separator 28 may be shifted in the left-right direction at one of the left and right edges of the bag-like separator 29, and the end faces 28c of the separator 28 do not have to be adjacent to each other. That is, at least one side of the bag-shaped separator 29 may be adjacent to the end surface 28c in the surface direction of the bag-shaped separator 29.

  In the coating process, the coat layer 29 b may be formed only on one of the outer surface and the inner surface of the bag-shaped separator 29. That is, the coat layer 29 b may be formed on at least one of the outer surface and the inner surface of the bag-shaped separator 29. Although it is conceivable that the coating layer 29b is formed only on one side of the separator 28 in advance and the non-formed planes of the coating layer 29b are joined together, in the above-described coating process, the coating agent is strictly applied only to one side. It is difficult to apply. In addition, since the components of the coating agent (binder and ceramic particles) impregnate even the non-coated surface of the coating agent, it is likely to be difficult to join the non-formed planes of the coat layer 29b. In this example, since the coat layer 29b is formed after the planes of the separators 28 are joined to each other, such a problem can be suitably solved. However, from the viewpoint of suppressing the shrinkage of the separator 28 at a high temperature, it is preferably formed on both surfaces of the bag-like separator 29.

  In the coating process, a region where the coating layer 29b is not formed may be provided on the end face 28c of the separator 28 that is adjacent to each other in the thermal welding process. That is, in the coating process, the coat layer 29b may be formed on at least a part of the end face 28c of the separator 28 adjacent to each other. According to this, in the coating process, the coat layer 29b is formed on at least a part of the end face 28c of the separator 28 adjacent to each other in the heat welding process, so that the coating layer 29b is not formed on the end face 28c. Thus, the region (area) where the end face 28c of the separator 28 is exposed can be reduced. For this reason, the shrinkage | contraction of the separator 28 in the end surface 28c of the separator 28 can be suppressed suitably.

  In the coating process, the coat layer 29b may be formed on a part of the end face 28c of the separator 28 arranged around the opening of the bag-shaped separator 29, or the coat layer 29b may not be formed.

In the coating process, the coat layer 29b may not be formed on the entire end face 28c of the separator 28.
In the bag-shaped separator 29, the negative electrode sheet 22 may be accommodated. That is, any one of the positive electrode sheet 21 and the negative electrode sheet 22 may be accommodated in the bag-shaped separator 29.

In the coating step, the coating layer 29b may be formed by spraying a coating agent by spraying or applying it with a brush or a blade.
O Although it was set as the metal foil 26, it may be a thin plate having a thickness that does not affect the decrease in the electric capacity of the secondary battery 10 or the production of the battery.

The shape of the positive electrode sheet 21 and the negative electrode sheet 22 may be changed as appropriate, such as a circle, an ellipse, or a hexagon.
The shape of the case 11 may be formed in a columnar shape or an elliptical column shape that is flat in the left-right direction.

  ○ The secondary battery 10 of the above embodiment is mounted on a vehicle (for example, an industrial vehicle or a passenger vehicle), and is charged by a generator mounted on the vehicle, while the compressor for an air conditioner is supplied with electric power supplied from the secondary battery 10 Alternatively, an electric motor for driving the wheels or an electrical component such as a car navigation system may be driven. According to this, as the secondary battery 10, the positive electrode sheet 21 and the negative electrode sheet 22 constituting the electrode body 25 can be prevented from being short-circuited at a high temperature, and the strength at the joint portion 29a can be prevented from being reduced. The safety as a vehicle can be improved.

The present invention may be embodied as an electric double layer capacitor as a power storage device.
The following technical idea (invention) can be understood from the embodiment.
(A) A flat separator for a power storage device that accommodates an electrode sheet by joining the flat surfaces of the separator to form a bag, and at least one of the outer surface and the inner surface and at least one of the end surfaces of the separator A bag-like separator for a power storage device, wherein a porous coat layer containing ceramic particles is formed in a part.

  S1... Step (formation process), S2... Step (coating process), S4... Step (accommodation process), S5... Step (stacking process), 10 ... secondary battery (power storage device), 21. , 22 ... negative electrode sheet (electrode sheet), 25 ... electrode body, 28 ... separator, 28c ... end face, 29 ... bag-like separator, 29b ... coat layer.

Claims (6)

A method of manufacturing a bag-like separator for a power storage device that houses an electrode sheet,
Forming the bag-shaped separator by joining the flat surfaces of the separator;
And a coating step of forming a porous coating layer containing ceramic particles on the inner surface of the bag-like separator after the forming step.   The method for producing a bag-shaped separator for a power storage device according to claim 1, wherein in the forming step, the planes of the separator are joined together by heat welding.   3. The method for manufacturing a bag-like separator for a power storage device according to claim 1, wherein in the coating step, the coat layer is formed on both outer and inner surfaces of the bag-like separator. In the forming step, by joining edges of the separator planes, at least one side of the bag-like separator, the end faces in the surface direction of the separator are adjacent to each other,
The said coating process WHEREIN: The said coating layer is formed in at least one part of the end surface of the said separator adjoined in the said formation process, The bag for electrical storage apparatuses of any one of Claims 1-3 characterized by the above-mentioned. Method for manufacturing a cylindrical separator.   5. The method for manufacturing a bag-like separator for a power storage device according to claim 4, wherein, in the coating step, the coating layer is formed on the entire end face of the separator that is adjacent in the forming step. In the forming step, the bag-shaped separator is formed so as to have an opening in which the edges of the separator are not joined together,
The method for manufacturing a bag-shaped separator for a power storage device according to claim 4 or 5, wherein, in the coating step, the coating layer is formed on an end face of the separator disposed around the opening.