JP6183526B2 - Electricity storage element - Google Patents

Description

  The present invention produces a wound electrode body obtained by alternately laminating and winding a positive electrode plate and a negative electrode plate, and two separators, a storage element having a wound electrode body, and a wound electrode body. The present invention relates to a winding device.

  Conventionally, in a power storage element including a battery such as a lithium ion battery, each of a positive electrode, a negative electrode, and two separators are alternately stacked, and the stacked sheet group is wound. There is a structure having an electrode body. In the electric storage element having such a wound electrode body, the sheet group is wound after fixing two separators to the winding core at the winding start position on the innermost circumference of the wound electrode body. At this time, as a method of fixing the two separators at the winding start position on the innermost circumference of the wound electrode body, there are a method of fixing by thermal welding, a method of fixing using a tape, etc. A method of fixing by heat welding is desirable from the viewpoint of durability and influence on battery performance. For example, Patent Document 1 discloses a wound battery in which a winding leading end portion of a separator is thermally welded to an axis (core).

JP 2009-224038 A

  However, since the effect of maintaining the insulation between the positive electrode and the negative electrode can be expected even when the battery is placed in a high-temperature environment, a separator with a heat-resistant layer such as a heat-resistant filler coated on one side of the separator ( Hereinafter, "heat-resistant coating separator") has been devised. When such a heat-resistant coating separator is applied to a wound electrode body, the heat-resistant layer of the heat-resistant coating separator is hard to be thermally welded, and the winding start position on the innermost circumference of the wound electrode body is welded and fixed. Is difficult. For this reason, it is difficult to wind the sheet group (the positive electrode, the negative electrode, and the two separators) laminated in a state where a tensile force is applied when the wound electrode body is manufactured. Thus, if the separator is not firmly welded and fixed in the innermost circumference of the wound electrode body, the positive electrode, the negative electrode, and the two separators are easily loosened during winding. A space (distance) is easily vacant between the negative electrode and the performance of the power storage element is likely to be deteriorated.

  Therefore, the present invention has been made in view of such a situation, and in a power storage element that employs a separator provided with a layer having a low heat-weldability such as a heat-resistant coating layer, it is possible to suppress a decrease in performance. An object is to provide a power storage element.

  In order to achieve the above object, the core, the positive electrode and the negative electrode, and the two separators disposed between the positive electrode and the negative electrode and having different thermal weldability on both surfaces are stacked. A winding body wound around a winding core, and at least one of the two separators is welded and fixed to the winding core on the first surface having the higher heat-weldability.

  According to this, since the wound body is welded and fixed to the winding core on the first surface having the higher heat weldability, at least one of the two separators having different heat weldability on both surfaces is wound. It is possible to easily realize winding of the positive electrode, the negative electrode, and the two separators in a state where a tensile force is applied to at least one of the separators at the position where the winding starts. For this reason, it can prevent that space (distance) vacates between the positive electrode and negative electrode of a winding type electrode body at the time of winding, and can suppress producing an electrical storage element with bad performance.

  In addition, one of the two separators may have the first surface welded and fixed to the core, and the two separators may have the first surfaces welded and fixed to each other.

  According to this, one of the first surfaces of the two separators is welded and fixed to the core, and further, the two separators are welded and fixed between the first surfaces having the higher weldability of the two separators. . That is, one separator can be directly welded and fixed to the core, and the other separator can be indirectly welded and fixed to the core via one separator. Thereby, two separators can be reliably welded and fixed to the core.

  The two separators may have their first surfaces welded and fixed to the core.

  According to this, each of the two separators is welded and fixed to the core by the first surface which is the surface having the higher weldability. For this reason, two separators can be reliably welded and fixed to the core.

  The winding core may include a main body portion and a branch portion branched from the main body portion, and at least one of the two separators may be welded to the branch portion on the first surface.

  Further, the first separator may be welded and fixed to the branch portion in a state where the branch portion is sandwiched between the two separators.

  One of the two separators may be welded and fixed to the branch portion on the first surface, and the other of the two separators may be welded and fixed to the main body portion on the first surface.

  Further, the winding core may be made of a material having a higher heat welding property than the first surface.

  According to this, the heat-weldability of the core is higher than the first surface of the two separators having higher heat-weldability. For this reason, it is possible to perform the welding and fixing between the core and the first surface of the separator and the welding and fixing between the insulating sheets at a lower temperature than the temperature at which the separators are welded and fixed. For this reason, welding fixation with a core and a separator can be performed easily.

  Further, the two separators include a first layer that forms the first surface, and a second layer that forms a second surface having a lower heat-weldability than the first surface, and the second layer May contain heat-resistant particles.

  According to this, the storage element uses a separator containing heat-resistant particles in order to maintain insulation between the positive electrode and the negative electrode constituting the electrode body when placed in a high temperature environment. In general, when the separator includes heat-resistant particles, the heat-welding property of the layer including the heat-resistant particles is extremely low. Even with such a separator having a surface with low heat-weldability, two separators can be reliably fixed to the core.

  The two separators may sandwich the positive electrode, and each of the second surfaces may be in contact with the positive electrode.

  According to this, since the electrode body of the electricity storage element sandwiches the positive electrode having a high electrode potential between the surfaces including the heat-resistant particles, it is possible to prevent the separator from being oxidized due to the high potential.

  The two separators sandwich one of the positive electrode and the negative electrode that has higher thermal conductivity, and each of the first surfaces has higher thermal conductivity than the positive electrode and the negative electrode. You may be in contact with

  According to this, when the electricity storage element is placed in a high temperature environment, the higher the thermal conductivity of the positive electrode or the negative electrode constituting the electrode body, the faster the temperature rises. As a result, the temperature of the first surface having the higher heat-welding property among the two separators rises, and the surface melts. Thereby, a part of the void | hole of a separator is plugged up. As a result, since the ionic conductivity of the separator is lowered, the storage element can be prevented from being charged / discharged while being placed in a high temperature environment.

  Note that the present invention can be realized not only as such a power storage element but also as a wound electrode body constituting such a power storage element. Further, it can be realized as a winding device for manufacturing a power storage element or a wound electrode body.

  According to the electricity storage device of the present invention, it is possible to easily maintain a state in which a tensile force is applied to the wound body during winding, and it is possible to suppress the production of an electricity storage device having poor performance.

FIG. 3 is a perspective view schematically showing the inside of the battery with a part of the wall portion of the container of the electricity storage device of Embodiment 1 of the present invention omitted. It is a perspective view which shows typically the external appearance of an electrode body. (A) is III-III sectional drawing of the electrode body of FIG. 2, (b) is the elements on larger scale of the A1 part of (a). It is a figure which shows the outline of a winding apparatus. It is the elements on larger scale of the A1 part of Fig.3 (a) of the electrical storage element which concerns on another form of Embodiment 1 of this invention. It is the elements on larger scale of the A2 part of Fig.3 (a) of the electrical storage element which concerns on Embodiment 2 of this invention. It is the elements on larger scale of the A2 part of Fig.3 (a) of the electrical storage element which concerns on another form of Embodiment 2 of this invention. It is the elements on larger scale of the A2 part of Fig.3 (a) of the electrical storage element which concerns on another form of Embodiment 2 of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Each of the embodiments described below shows a preferred specific example of the present invention. The shapes, materials, components, arrangement positions and connection forms of the components shown in the following embodiments are examples, and are not intended to limit the present invention. The invention is limited by the claims. Therefore, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims indicating the highest concept of the present invention are not necessarily required to achieve the object of the present invention. It will be described as constituting a preferred form.

(Embodiment 1)
FIG. 1 is a perspective view schematically showing the inside of a battery by omitting a part of a wall portion of a container of a storage element.

  The storage element 10 is a secondary battery that can charge electricity and discharge electricity, and more specifically, is a non-aqueous electrolyte battery such as a lithium ion secondary battery.

  As shown in the figure, the power storage element 10 includes a container 100, a positive electrode terminal 200, and a negative electrode terminal 300, and the container 100 includes a lid plate 110 that is an upper wall. In addition, an electrode body 120, a positive electrode current collector 130, and a negative electrode current collector 140 are disposed inside the container 100.

  Note that a liquid such as an electrolytic solution is sealed inside the container 100 of the power storage element 10, but the liquid is not shown. Moreover, the electrical storage element 10 is not limited to a non-aqueous electrolyte battery, and may be a secondary battery other than the non-aqueous electrolyte battery or a capacitor.

  The container 100 includes a container body having a rectangular cylindrical shape made of metal and having a bottom, and a metal lid plate 110 that closes an opening of the container body. In addition, the container 100 can be hermetically sealed by welding the lid plate 110 and the container body after the electrode body 120 and the like are accommodated therein.

  The electrode body 120 includes a positive electrode, a negative electrode, and a separator, and is a member that can store electricity. Specifically, the electrode body 120 is formed by winding a layered arrangement so that a separator is sandwiched between a negative electrode and a positive electrode so that the whole becomes an oval shape. In addition, in the same figure, although the ellipse shape was shown as a shape of the electrode body 120, circular shape or elliptical shape may be sufficient. The detailed configuration of the electrode body 120 will be described later.

  The positive electrode terminal 200 is an electrode terminal electrically connected to the positive electrode of the electrode body 120, and the negative electrode terminal 300 is an electrode terminal electrically connected to the negative electrode of the electrode body 120. That is, the positive electrode terminal 200 and the negative electrode terminal 300 lead the electricity stored in the electrode body 120 to the external space of the power storage element 10, and in order to store the electricity in the electrode body 120, It is an electrode terminal made of metal for introducing. The positive electrode terminal 200 and the negative electrode terminal 300 are attached to the lid plate 110 disposed above the electrode body 120.

  The positive electrode current collector 130 is disposed between the positive electrode of the electrode body 120 and the side wall of the container 100, and is a member having conductivity and rigidity that is electrically connected to the positive electrode terminal 200 and the positive electrode of the electrode body 120. It is. The positive electrode current collector 130 is made of aluminum, like the positive electrode of the electrode body 120.

  The negative electrode current collector 140 is a member that is disposed between the negative electrode of the electrode body 120 and the side wall of the container 100 and has electrical conductivity and rigidity that are electrically connected to the negative electrode terminal 300 and the negative electrode of the electrode body 120. It is. The negative electrode current collector 140 is made of copper, like the negative electrode of the electrode body 120.

  FIG. 2 is a perspective view schematically showing the appearance of the electrode body. 3A is a cross-sectional view taken along the line III-III of the electrode body of FIG. 2, and FIG. 3B is a partially enlarged view of a portion A1 in FIG. FIG. 3B is a diagram in which only the winding start portion of the wound body is extracted from the winding core. Actually, the positive electrode plate and the negative electrode plate, and two separators are further outside. Has been wound several times.

  As shown in FIGS. 2, 3 (a), and 3 (b), the electrode body 120 as a wound electrode body includes a winding core 126, a wound body 121, and an insulating sheet 127. The

  The winding core 126 is formed by welding and fixing the outermost peripheral end at the third position P3 in a state where a long belt-like winding sheet made of polypropylene or polyethylene is folded in three, and the winding core 121 is the outermost end of the winding body 121. Arranged on the inner circumference.

  The wound body 121 is disposed between a positive electrode plate 122 as a positive electrode and a negative electrode plate 123 as a negative electrode, and between the positive electrode plate 122 and the negative electrode plate 123, and has two separators 124 and 125 positive electrode plates having different thermal weldability on both surfaces. In a state in which 122 is laminated, the core is wound around the core 126 so as to have an oval cross section. More specifically, the wound body 121 includes a first separator 124, a negative electrode plate 123, and a second separator 125 stacked in this order, and the first separator 124 and the second separator 125 are attached to the core 126. It is configured by welding and fixing, and winding four sheets of the positive electrode plate 122, the first separator 124, the negative electrode plate 123, and the second separator 125 around the winding core 126 (winding shaft). . That is, the two separators 124 and 125 sandwich the positive electrode plate 122 as the positive electrode, and the second layers 124 b and 125 b forming the second surfaces of the separators 124 and 125 are in contact with the positive electrode plate 122. The two separators 124 and 125 sandwich the negative electrode plate 123 as a negative electrode, and the first layers 124a and 125a forming the first surfaces of the separators 124 and 125 are in contact with the negative electrode plate. The wound body 121 is wound without the positive electrode plate 122 and the negative electrode plate 123 on the outermost periphery (the last round).

  The wound body 121 is wound in a state where the positive electrode plate 122 and the negative electrode plate 123 on which the active material is applied and the two separators 124 and 125 having different thermal weldability on both surfaces are alternately laminated. It is wound around a core 126. That is, the wound body 121 is wound so that the cross section has an oval shape in a state where the positive electrode plate 122, the first separator 124, the negative electrode plate 123, and the second separator 125 are stacked in this order. It consists of.

  The positive electrode plate 122 is obtained by forming a positive electrode active material layer on the surface of a long belt-shaped positive electrode current collector sheet made of aluminum. In addition, the positive electrode plate 122 used for the electrical storage element 10 according to the present invention is not particularly different from that conventionally used, and a commonly used one can be used.

For example, as the positive electrode active material, polyanion compounds such as LiMPO ₄ , LiMSiO ₄ , LiMBO ₃ (M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.), lithium titanate, etc. , Spinel compounds such as lithium manganate, lithium transition metal oxides such as LiMO ₂ (M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.), etc. can be used. .

  The negative electrode plate 123 is obtained by forming a negative electrode active material layer on the surface of a long strip negative electrode current collector sheet made of copper. In addition, the negative electrode plate 123 used for the electricity storage device 10 according to the present invention is not particularly different from those conventionally used, and those normally used can be used.

For example, as the negative electrode active material, a known material can be appropriately used as long as it is a negative electrode active material capable of occluding and releasing lithium ions. For example, lithium metal and lithium alloys (lithium metal-containing alloys such as lithium-aluminum, lithium-lead, lithium-tin, lithium-aluminum-tin, lithium-gallium, and wood alloys) and lithium can be occluded / released. Alloys, carbon materials (eg, graphite, non-graphitizable carbon, graphitizable carbon, low-temperature fired carbon, amorphous carbon, etc.), metal oxides, lithium metal oxides (Li ₄ Ti ₆ O ₁₂ etc.), polyphosphate compounds Etc.

  The first separator 124 and the second separator 125 are long strip separators disposed between the positive electrode plate 122 and the negative electrode plate 123. The first layer 124a, 125a and the second layer 124b, 125b I have.

  The first layers 124a and 125a are base layers of the first separator 124 and the second separator 125, and are microporous sheets containing a thermoplastic resin.

  Specifically, a resin porous membrane having a woven or non-woven fiber of polymer, natural fiber, hydrocarbon fiber, glass fiber or ceramic fiber is used as the first layers 124a and 125a. The porous resin membrane preferably has woven or non-woven polymer fibers. In particular, the porous resin membrane preferably has a polymer fabric or fleece or is such a fabric or fleece. As polymer fibers, preferably polyacrylonitrile (PAN), polyamide (PA), polyester, such as polyethylene terephthalate (PET) and / or polyolefin (PO), such as polypropylene (PP) or polyethylene (PE) or such polyolefins Having a non-conductive fiber of polymer selected from a mixture of The resin porous membrane may be a polyolefin microporous membrane, a nonwoven fabric, paper or the like, and is preferably a polyolefin microporous membrane. As the porous polyolefin layer, polyethylene, polypropylene, or a composite film thereof can be used. In consideration of the influence on the battery characteristics, the thickness of the first layers 124a and 125a is preferably about 5 to 30 μm.

  The second layers 124b and 125b are layers different in material from the first layers 124a and 125a, which are disposed on the first layers 124a and 125a. In the present embodiment, the second layers 124b and 125b are heat-resistant coating layers coated on the first layers 124a and 125a. Here, the heat resistant coating layer is, for example, a layer containing inorganic particles or a heat resistant resin (heat resistant particles).

Specifically, the inorganic particles are composed of one or more of the following inorganic substances alone or as a mixture or a composite compound. For example, iron _{oxide, SiO 2, Al 2 O 3} , TiO 2, BaTiO 2, ZrO, alumina - oxide such as silica composite oxide, aluminum nitride, nitrides particles, calcium fluoride, such as silicon nitride, barium fluoride , Sparingly soluble ionic crystal particles such as barium sulfate, covalently bonded crystal particles such as silicon and diamond, clay particles such as talc and montmorillonite, boehmite, zeolite, apatite, kaolin, mullite, spinel, olivine, sericite, bentonite, Examples of the inorganic substance include substances derived from mineral resources such as mica or artificial products thereof. In addition, the above-mentioned inorganic substance is a material having an electrical insulating property on the surface of conductive fine particles such as oxide fine particles such as SnO ₂ and tin-indium oxide (ITO), and carbonaceous fine particles such as carbon black and graphite (for example, In addition, fine particles imparted with electrical insulation by surface treatment with the above-described material constituting the electrically insulating inorganic particles) may be used.

  The second layers 124b and 125b have lower heat weldability than the first layers 124a and 125a. That is, the first separator 124 and the second separator 125 are the first layers 124a and 125a that form the first surface with the higher thermal weldability, and the second layer that forms the second surface with the lower thermal weldability. 124b, 125b.

  At least one of the two separators 124 and 125 (in the first embodiment, the first separator 124) is welded and fixed to the core 126 in the first layer 124a forming the first surface having the higher heat-weldability. The The two separators 124 and 125 are laminated so that the first layers 124a and 125a forming the first surface face each other, and the first layer 124a and the first layer 125a facing each other are in the second position P2. And are fixed to each other by welding. The first surface (first layer 124a) of one of the two separators 124 and 125 is welded and fixed to the core 126 at the first position P1.

  One end of the insulating sheet 127 is welded and fixed to at least one of the two separators 124 and 125, and the other end is already wound in a state in which the insulating sheet 127 is further wound around the outermost periphery of the wound body 121. Then, it is welded and fixed to the insulating sheet 127 itself disposed inside. Since the insulating sheet 127 goes around the outermost periphery of the wound body 121 and is welded and fixed while applying a tensile force to the insulating sheet 127 itself, the wound body 121 includes each sheet (the positive electrode plate 122, the negative electrode plate 123, and the The distance between the two separators 124, 125) is maintained so as not to increase.

  FIG. 4 is a diagram showing an outline of the winding device 500. The wound body 121 is manufactured by the winding device 500. The winding device 500 includes a winding unit 501 and a welding fixing unit 502. The welding fixing portion 502 is configured to weld and fix the first separator 124 and the core 126 at the first position P1 shown in FIG. 3B and to weld the two separators 124 and 125 at the second position P2. Fix and do. As shown in FIG. 4, the winding unit 501 sandwiches the separators 124 and 125 welded and fixed directly and indirectly to the core 126 by the welding and fixing unit 502 between the positive electrode plate 122 and the negative electrode plate 123. In the laminated state, it is wound around the core 126 together with the positive electrode plate 122 and the negative electrode plate 123.

  According to the electricity storage device 10 according to the first exemplary embodiment, the wound body 121 includes the first separator 124 having at least one of the two separators 124 and 125 having different heat weldability on both surfaces. Since the first layer 124 a forming the first surface is welded and fixed to the core 126, the positive electrode plate 122 is in a state where a tensile force is applied to the first separator 124 at the winding start position of the wound body 121. In addition, winding the negative electrode plate 123 and the two separators 124 and 125 can be easily realized. For this reason, it is possible to prevent a space (distance) between the positive electrode plate 122 and the negative electrode plate 123 of the electrode body 120 as a wound electrode body, and the performance of the manufactured power storage element 10 is reduced. Can be suppressed. Moreover, since the state where the tensile force is applied to the positive electrode plate 122 and the negative electrode plate 123 and the two separators 124 and 125 is maintained, the relative position of these members can be prevented from changing and the separators 124 and 125 from contracting. it can. As a result, direct contact between the positive electrode plate 122 and the negative electrode plate 123 can be suppressed, and deterioration of the performance of the power storage element 10 can be suppressed.

  Further, according to the electricity storage device 10 according to the first exemplary embodiment, the first layer 124a that forms the first surface of the first separator 124, which is one of the two separators 124 and 125, is welded and fixed to the core 126. Further, the two separators 124 and 125 are welded and fixed by the first layers 124a and 125a forming the first surface of the two separators 124 and 125 having the higher weldability. That is, the first separator 124 can be directly welded and fixed to the core 126, and the second separator 125 can be indirectly fixed to the core 126 via the first separator 124. Thereby, the two separators 124 and 125 can be reliably welded and fixed to the core 126.

  Moreover, according to the electrical storage element 10 according to the first embodiment, when it is placed in a high temperature environment, it is heat resistant to maintain the insulation between the positive electrode plate 122 and the negative electrode plate 123 constituting the electrode body 120. Separators 124 and 125 containing particles are used. In general, when the separator includes heat-resistant particles, the heat-welding property of the layer including the heat-resistant particles is extremely low. Even with the separators 124 and 125 having such a low heat-weldable surface, the two separators 124 and 125 can be reliably fixed to the core 126.

  In addition, according to the electricity storage device 10 according to the first exemplary embodiment, the electrode body 120 of the electricity storage device 10 has a high electrode potential between the second surfaces formed by the second layers 124b and 125b that are layers containing heat-resistant particles. Since the positive electrode plate 122 is sandwiched, oxidation of the separators 124 and 125 due to a high potential can be prevented.

  In addition, according to the electric storage element 10 of the first embodiment, the winding core 126 is more than the first layers 124a and 125a that form the first surface on which the first separator 124 and the second separator 125 have higher heat weldability. However, the heat weldability is not necessarily high. Even if the core 126 has a higher heat-weldability than the second layers 124b and 125b that form the second surface of the first separator 124 and the second separator 125 having the lower heat-weldability, It can be welded and fixed to at least one of the first layers 124 a and 125 a of the first separator 124 and the second separator 125.

  In addition, according to the electricity storage device 10 of the first embodiment, the first layer 124a forming the first surface of the first separator 124 is directly welded and fixed to the core 126, and the first surface of the second separator 125 is fixed. The first layer 125a forming the film is indirectly fixed to the core 126 by welding and fixing to the first separator 124. However, the present invention is not limited to this. For example, as shown in FIG. 5, the first layer 124 a that forms the first surface of the first separator 124 is welded and fixed at the first position P <b> 11 of the core 126 to form the first surface of the second separator 125. By welding and fixing the first layer 125a at the second position P12 that is shifted from the first position P11 of the core 126, both the first separator 124 and the second separator 125 are directly attached to the core 126. Alternatively, it may be a form that is fixed by welding.

In addition, according to the electrical storage element 10 according to the first embodiment, the two separators 124 and 125 sandwich the positive electrode plate 122 as the positive electrode, and the second layer 124b that forms the respective second surfaces. , 125b are in contact with the positive electrode plate 122. Further, the two separators 124 and 125 sandwich the negative electrode plate 123 as the negative electrode, and the first layers 124a and 125a forming the first surfaces of the separators 124 and 125 are in contact with the negative electrode plate. However, when the negative electrode plate has a higher thermal conductivity than the positive electrode plate, such as when LiMO _{2 is used for} the positive electrode plate and a carbon material is used for the negative electrode plate, the two separators 124 and 125 are the positive electrode plate 122 as the positive electrode. In addition, the first layers 124a and 125a forming the respective first surfaces are in contact with the positive electrode plate 122, and the two separators 124 and 125 sandwich the negative electrode plate 123 as a negative electrode. In addition, the second layers 124b and 125b forming the respective second surfaces may be in contact with the negative electrode plate 123. That is, the two separators 124 and 125 sandwich the one having the higher thermal conductivity between the positive electrode plate 122 and the negative electrode plate 123, and the first surfaces of the separators 124 and 125 are the positive electrode plate 122 and the negative electrode plate 123. If the configuration is in contact with the higher thermal conductivity, the following effects are obtained.

  That is, when the power storage element 10 is placed in a high temperature environment, the temperature of the positive electrode plate 122 or the negative electrode plate 123 constituting the electrode body 120 increases more quickly when the heat conductivity is higher. As a result, the temperature of the first surface of the two separators 124 and 125 having the higher heat-weldability increases, and the surface melts. As a result, some of the holes in the separators 124 and 125 are closed. As a result, since the ionic conductivity of the separators 124 and 125 is lowered, it is possible to prevent the storage element 10 from being charged and discharged while being placed in a high temperature environment.

(Embodiment 2)
FIG. 6 is a partial enlarged view of the portion A2 in FIG. 3A of the energy storage device 20 according to Embodiment 2 of the present invention. The power storage device 20 according to the second embodiment is different from the power storage device 10 according to the first embodiment in the position of welding and fixing between the two separators 124 and 125 and the core 126, and other configurations are not illustrated. Since this is the same as the power storage element 10 of the first embodiment, the description thereof is omitted.

  In the electricity storage device 20 according to the second embodiment, as shown in FIG. 6, the core 126 is a position of the outermost periphery of the wound sheet wound by winding one or more long strip-shaped wound sheets. It is formed by welding and fixing two or more wound sheets that overlap each other at a third position P23 that is a position closer to the innermost end than the end on the outermost peripheral side of the wound sheet. The winding core 126 is formed on the outer side of the main body 226a formed by winding the wound sheet one or more times, and from the third position P3 where the wound sheets are welded to each other. And a branching portion 226b between the outermost ends.

  In the state in which the two separators 124 and 125 sandwich the branch portion 226b, the first layers 124a and 125a forming the first surfaces of the two separators 124 and 125 are welded and fixed to the branch portion 226b. Specifically, the first separator 124 and the second separator 125 are stacked so that the first layers 124a and 125a forming the first surface face each other, and the core 226 is formed at the innermost end. Lamination is performed in such a manner that the end portion of the branch portion 226b is sandwiched. In this state, in the first separator 124, the first layer 124a forming the first surface is welded and fixed to the outer surface of the branch portion 226b at the first position P21, and the second separator 125 forms the first surface. The first layer 125a to be welded is fixed to the inner surface of the branch portion 226b at the second position P22. The first separator 124 and the second separator 125 welded and fixed to the outermost peripheral edge of the core 126 in this manner are disposed between the positive electrode plate 122 and the negative electrode plate 123, and are thus connected to the positive electrode plate 122 and the negative electrode plate 123. It is beaten with.

  According to the electricity storage device 20 according to the second exemplary embodiment, each of the two separators 124 and 125 forms a first surface which is a surface having a higher weldability with respect to the branch portion 226b of the core 226. The first layers 124a and 125a are welded and fixed. For this reason, the two separators 124 and 125 can be reliably welded and fixed to the core 126.

  In addition, according to the electricity storage device 20 according to the second embodiment, both the first separator 124 and the second separator 125 are welded to the branch portion 226b of the core 226 by the first layers 124a and 125a forming the first surface. Although fixed, the two separators 124 and 125 are not limited to be welded and fixed to the branch portion 226b.

  For example, as shown in FIG. 7, the electricity storage device 20 is formed by welding and fixing the first layer 124 a of the first separator 124 to the outer surface of the branching portion 226 b at the first position P31. The configuration may be such that 125a is welded and fixed to the outer surface of the main body 226a at the second position P32. Further, for example, as shown in FIG. 8, the power storage element 20 welds and fixes the first layer 124 a of the first separator 124 to the inner surface of the branch portion 226 b at the first position P 41, and The configuration may be such that the single layer 125a is welded and fixed to the outer surface of the main body 226a at the second position P42.

  The power storage element according to one embodiment of the present invention is useful as a power storage element that can suppress a decrease in performance in a power storage element that employs a separator provided with a layer having low heat-weldability such as a heat-resistant coating layer.

10, 20 Storage element 100 Container 110 Lid plate 120 Electrode body 121 Winding body 122 Positive electrode plate 123 Negative electrode plate 124 First separator 124a, 125a First layer 124b, 125b Second layer 125 Second separator 126, 226 Core 127 Insulation Sheet 130 Positive electrode current collector 140 Negative electrode current collector 200 Positive electrode terminal 226a Main body portion 226b Branching portion 300 Negative electrode terminals P1, P11, P21, P31, P41 First position P2, P12, P22, P32, P42 Second position P3 , P23 Third position

Claims (3)

Winding core,
A wound body formed by winding the positive electrode and the negative electrode, and the two separators disposed between the positive electrode and the negative electrode and having different heat-weldability on both surfaces in a stacked state; ,
With
At least one of the two separators is welded and fixed to the core on the first surface having the higher heat-weldability,
The two separators sandwich one of the positive electrode and the negative electrode having a higher thermal conductivity, and each of the first surfaces has a higher thermal conductivity between the positive electrode and the negative electrode. A power storage element in contact. The power storage element according to claim 1, wherein the core is made of a material having higher heat-weldability than the first surface.   Winding core,
  A wound body formed by winding the positive electrode and the negative electrode, and the two separators disposed between the positive electrode and the negative electrode and having different heat-weldability on both surfaces in a stacked state; ,
  With
  At least one of the two separators is welded and fixed to the core on the first surface having the higher heat-weldability,
  The core is made of a material having higher heat-weldability than the first surface.
  Power storage element.

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