JP2018160349A - Electric storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electricity storage device capable of suppressing decrease in charge/discharge capacity when charging/discharging at a high rate in addition to increasing capacity. In an electricity storage device 10A including a pair of electrodes 12A and 14A and a separator 16 provided between the pair of electrodes 12A and 14A, the pair of electrodes 12A and 14A include a current collector 18 and The active material layers 20 and 24 are formed on the surface of the current collector 18, and the active material layers 20 and 24 are provided with a plurality of first holes 26 on the surface in contact with the separator 16. The separator 16 has a plurality of second holes 28, and the second holes 28 are positioned so as to overlap with the first holes 26. [Selection diagram] Figure 1

Description

  The present invention relates to an electricity storage device, and more particularly to a lithium ion secondary battery (LiB), a lithium ion capacitor (LiC), and an electric double layer capacitor (EDLC).

  A lithium ion secondary battery (LiB), a lithium ion capacitor (LiC), and an electric double layer capacitor (EDLC) include a pair of electrodes and a separator provided between the electrodes. The separator is required to have ion permeability by being impregnated with an electrolytic solution, and a polyethylene resin having micropores is often used as a material. When a power storage device reaches an abnormally high temperature due to a short circuit or the like, a separator made of polyethylene resin closes the micropores by melting and stops the abnormal reaction.

  As such a separator, Patent Document 1 discloses a separator in which a through hole of 50 μm or less is formed. Patent Document 2 has a first separator and a second separator formed of a resin film. The first separator is disposed between the electrode and the second separator and penetrates only in the second separator in the thickness direction. A separator in which a liquid retaining hole is formed is disclosed. In the case of Patent Document 2, the second separator having a liquid retaining hole prevents the electrolyte from being drained, and the first separator having no hole prevents a short circuit.

JP 2003-238730 A JP2015-72829A

  In addition to increasing capacity, power storage devices are required to have rapid charge / discharge characteristics at a large current (high rate). However, as shown in Patent Document 1, since the size of the through-hole formed in the separator is fine, the movement of ions is hindered, and the charge / discharge capacity during charge / discharge at a high rate is reduced. There's a problem. In the case of Patent Document 2 described above, although the second separator has a large liquid retaining hole, there is a problem in that the first separator disposed between the second separator and the electrode hinders the movement of ions.

  An object of this invention is to provide the electrical storage device which can suppress the fall of the charging / discharging capacity | capacitance at the time of charging / discharging at high rate in addition to high capacity | capacitance.

  A first aspect of the present invention is an electricity storage device including a pair of electrodes and a separator provided between the pair of electrodes, wherein the pair of electrodes is formed on a current collector and a surface of the current collector The active material layer has a plurality of first holes on a surface in contact with the separator, the separator has a plurality of second holes, and the first The two holes are at positions that overlap the first hole.

  A second aspect of the present invention is the invention based on the first aspect, wherein the plurality of second holes have a diameter of 50 μm to 500 μm and a center interval of 1 to 5 mm.

  A third aspect of the present invention is the invention based on the first or second aspect, wherein the plurality of first holes have a diameter of 200 μm to 700 μm and a depth of 20 μm which is the thickness of the active material layer. % Or more.

  A fourth aspect of the present invention is the invention based on any one of the first to third aspects, wherein the plurality of first holes have a bottom formed by the current collector. Features.

  A fifth aspect of the present invention is an invention based on any one of the first to fourth aspects, wherein the plurality of second holes have an inner wall having thermoplasticity.

  A sixth aspect of the present invention is an invention based on any one of the first to fifth aspects, wherein the first hole is larger in diameter than the second hole.

  In the electricity storage device according to the first aspect of the present invention, since the first hole is formed in the active material layer, in addition to the surface of the active material layer, electrons can be formed at a position deep in the thickness direction from the surface of the active material layer. Exchange of ions, insertion and removal of ions occur, active materials deep in the thickness direction from the surface of the active material layer can be used effectively, and the distance of ion movement within the electrode does not become too long, Furthermore, the active material can be used effectively and the capacity can be increased. In addition, since the second hole is formed in the separator and ions can pass through the separator more smoothly, a decrease in charge / discharge capacity when charging / discharging at a high rate can be suppressed. Furthermore, since the second hole of the separator is provided at a position where it overlaps the first hole of the active material layer, ions can pass through the separator faster, and the charge / discharge capacity is reduced when charging / discharging at a high rate. It can be suppressed more.

  In the electricity storage device according to the second aspect of the present invention, the range in which the ions in the electrolytic solution reach in one first hole at the position overlapping the second hole does not overlap, and the ions in the electrolytic solution reach in the active material layer. Since difficult areas decrease, the active material that can be used effectively increases.

  In the electricity storage device according to the third aspect of the present invention, ions in the electrolytic solution easily reach a deep position in the depth direction of the active material layer, and the active material that can be effectively used increases.

  In the electricity storage device according to the fourth aspect of the present invention, the liquid retention of the first hole can be improved.

  In the electric storage device according to the fifth aspect of the present invention, an effect of stopping an abnormal reaction due to a short circuit or the like can be obtained.

  In the electric storage device according to the sixth aspect of the present invention, the number of active materials that can be used effectively increases.

It is a longitudinal cross-sectional view which shows typically the electrode structure of the lithium ion secondary battery which concerns on this embodiment. It is a top view of the separator which concerns on this embodiment. It is a longitudinal cross-sectional view which shows typically the electrode structure of the lithium ion secondary battery which concerns on a modification.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(overall structure)
As shown in FIG. 1, a lithium ion secondary battery 10A as an electricity storage device includes a positive electrode 12A, a negative electrode 14A, and a separator 16. The positive electrode 12A and the negative electrode 14A are disposed to face each other with the separator 16 in between. The positive electrode 12A, the negative electrode 14A, and the separator 16 are made of, for example, LiPF ₆ , LiBF ₄ , LiClO in a nonaqueous solvent containing EC (ethylene carbonate), DEC (diethyl carbonate), DMC (dimethyl carbonate), MEC (methyl ethyl carbonate), and the like. It is accommodated in a case (not shown) in a state immersed in an electrolytic solution in which a lithium salt such as ₄ is mixed.

  The positive electrode 12 </ b> A includes a current collector 18 and a positive electrode active material layer 20 formed on one surface of the current collector 18. As the current collector 18, an aluminum foil can be mainly used.

The positive electrode active material layer 20 includes a positive electrode active material, a positive electrode conductive additive, and a binder. The positive electrode active material layer 20 has a first hole 26 formed on the surface in contact with the separator 16. As the positive electrode active material, LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiMnO ₂ , LiFePO _4, or the like can be used. As the conductive aid, carbon black such as acetylene black and ketjen black, VGCF, graphite, and the like can be used. As the binder, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), ethylene-propylene-diene copolymer (EPDM), styrene-butadiene rubber (SBR), or the like can be used. The thickness of the positive electrode active material layer 20 is preferably 50 to 200 μm.

  The negative electrode 14 </ b> A includes a current collector 22 and a negative electrode active material layer 24 formed on one surface of the current collector 22. The current collector 22 can be made of copper foil, stainless steel foil, nickel foil, or the like. In the following description, when the positive electrode active material layer 20 and the negative electrode active material layer 24 are not particularly distinguished, they are collectively referred to as an active material layer.

The negative electrode active material layer 24 includes a negative electrode active material and a binder. The negative electrode active material layer 24 has a first hole 26 formed on the surface in contact with the separator 16. As the negative electrode active material, natural graphite, artificial graphite, silicon (Si), silicon oxide (SiO), tin (Sn), tin-cobalt compound (Sn-Co), stannic oxide (SnO ₂ ), and titanic acid Lithium (Li ₄ Ti ₅ O ₁₂ ) or the like can be used. As the binder, polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), or the like can be used.

  The first hole 26 formed in the negative electrode active material layer 24 is disposed at a position facing the first hole 26 formed in the positive electrode active material layer 20 with the separator 16 interposed therebetween. The first hole 26 has a bottom portion 27 formed of an active material layer. The first hole 26 shown in the figure is cylindrical.

  The diameter of the first hole 26 is preferably 200 to 700 μm. When the diameter of the first hole 26 is within the above range, lithium ions solvated in the electrolyte present in the first hole 26 can smoothly move. The depth of the first hole 26 is desirably 20% or more of the thickness of the active material layer. When the depth of the first hole 26 is 20% or more, lithium ions in the electrolytic solution easily reach a deep position in the depth direction of the active material layer, and the active material that can be effectively used increases. The first hole 26 is preferably larger in diameter than the second hole 28 formed in the separator 16. When the diameter of the first hole 26 is 2 to 10 times the diameter of the second hole 28, the active material layer can be effectively used more reliably.

  Separator 16 is formed with sheet materials, such as a synthetic resin nonwoven fabric, a polyethylene porous film, a polypropylene porous film, and a cellulose nonwoven fabric. In the separator 16, a second hole 28 penetrating in the thickness direction is formed at a position overlapping the first hole 26. The diameter of the second hole 28 is preferably 50 μm to 500 μm. When the diameter of the second hole 28 is within the above range, the movement of lithium ions is not hindered, and when the lithium ion secondary battery 10A reaches an abnormally high temperature, the micropores are blocked by melting and abnormal reaction occurs. Demonstrate the function to stop.

  As shown in FIG. 2, the first hole 26 and the second hole 28 have a circular shape in plan view, and are formed at equal intervals vertically and horizontally. The center distance between the first hole 26 and the second hole 28 is preferably 1 to 5 mm. If the distance between the centers of the first hole 26 and the second hole 28 is within the above range, the range in which the lithium ions in the electrolyte in one first hole 26 reach does not overlap, and the lithium in the electrolyte in the active material layer Since the area where ions are difficult to reach decreases, the active material that can be used effectively increases.

(Production method)
A method for manufacturing the lithium ion secondary battery 10A will be described. The active material, the binder, and the conductive assistant are weighed so as to have a predetermined mass ratio. After weighing, the binder is added to the solvent and stirred for a predetermined time. Furthermore, an active material and a conductive additive are added and stirred, and the viscosity is adjusted to prepare a slurry. The slurry is a liquid used for forming an active material layer on the surfaces of the current collectors 18 and 22.

  Next, the prepared slurry is applied to the surfaces of the current collectors 18 and 22 formed in a predetermined size, and dried at a predetermined temperature for a predetermined time to form an active material layer. The coating method is not particularly limited, and for example, a doctor blade method or a die coating method can be used.

  Next, the current collectors 18 and 22 on which the active material layer is formed are passed through a roll press machine, and the active material layer is formed to a predetermined thickness. The active material density of the active material layer can be adjusted by changing the thickness of the active material layer by adjusting the gap distance between the rolls of the roll press machine.

  Finally, a sword-like jig having a large number of needles at predetermined intervals is pierced into the surface of the active material layer to form the first hole 26, thereby obtaining the positive electrode 12A and the negative electrode 14A.

  In addition, the small 1st hole 26 with a diameter of 500 micrometers or less can also be formed by laser processing. In this method, the size of the first hole 26 to be formed can be adjusted by changing the diameter of the laser beam to be irradiated, and for example, the first hole 26 having a truncated cone shape can be formed by changing the incident angle.

  The separator 16 can be obtained by piercing the sheet material with a jig such as a sword mountain with a large number of needles at predetermined intervals, as in the case of the positive electrode and the negative electrode, and forming the second hole 28. The second hole 28 can also be formed by laser processing. However, when the second hole 28 is formed by laser processing, the inner wall of the second hole 28 is melted by heat at the time of laser processing and the thermoplasticity is lost, so that the power storage device reaches an abnormally high temperature Thus, the effect of closing the second hole 28 by melting is not obtained. Therefore, in order to obtain an effect of stopping an abnormal reaction due to a short circuit or the like, it is necessary to maintain the thermoplasticity of the inner wall of the second hole 28 by forming the second hole 28 using a jig such as the Kenzan. preferable.

  Next, the second hole 28 and the first hole 26 are aligned, the separator 16 is sandwiched, the positive electrode 12A is disposed on one side, and the negative electrode 14A is disposed on the other side. An ion secondary battery 10A can be manufactured.

(Operation and effect)
The operation of the lithium ion secondary battery 10A according to this embodiment will be described. In the lithium ion secondary battery 10 </ b> A, the positive electrode 12 </ b> A and the negative electrode 14 </ b> A are immersed in the electrolytic solution, and the electrolytic solution is also present in the first hole 26 formed in the active material layer. Since the first hole 26 is formed in the active material layer, the electrolytic solution also exists at a deep position in the thickness direction from the surface of the active material layer.

  First, an operation during charging of the lithium ion secondary battery 10A will be described. A voltage is applied between the positive electrode 12A and the negative electrode 14A through an external circuit (not shown). Then, lithium in the active material of the positive electrode 12A is released into the electrolytic solution as lithium ions. Since the first hole 26 is formed in the positive electrode active material layer 20 of the positive electrode 12 </ b> A, this reaction is performed not only on the surface of the positive electrode active material layer 20 but also at a position deep in the thickness direction from the surface of the positive electrode active material layer 20. Progresses.

  Electrons emitted from the active material move to the negative electrode 14A through an external circuit (not shown). On the other hand, lithium ions move to the negative electrode 14A via the electrolytic solution and the separator 16. Since the second hole 28 is formed in the separator 16 at a position overlapping the first hole 26, lithium ions can pass through the separator 16 smoothly.

  The lithium ions that have passed through the separator 16 are inserted into the active material of the negative electrode 14A and receive electrons. Since the first hole 26 is also formed in the negative electrode active material layer 24 of the negative electrode 14A, lithium ions are not only in the surface of the negative electrode active material layer 24 but also in a position deep in the thickness direction from the surface of the negative electrode active material layer 24. However, this reaction proceeds. The lithium ion secondary battery 10A is charged as described above.

  Next, the operation during discharging of the lithium ion secondary battery 10A will be described. The positive electrode 12A and the negative electrode 14A are connected to an external load (not shown). Then, lithium in the active material is released into the electrolytic solution as lithium ions at the negative electrode 14A. Since the first hole 26 is formed in the negative electrode active material layer 24 of the negative electrode 14 </ b> A, this reaction is performed not only on the surface of the negative electrode active material layer 24 but also at a position deep in the thickness direction from the surface of the negative electrode active material layer 24. Progresses.

  Electrons emitted from the active material move from the negative electrode 14A through the external load to the positive electrode 12A. The lithium ions are desorbed from the active material and move to the positive electrode 12A through the electrolytic solution and the separator 16. Lithium ions can pass through the separator 16 more smoothly through the second hole 28 formed at a position overlapping the first hole 26. The lithium ions that have passed through the separator 16 are inserted into the active material by the positive electrode 12A. Also in this case, since the first hole 26 is formed in the positive electrode active material layer 20, lithium ions move in the electrolytic solution existing in the first hole 26, and the movement of the lithium ions becomes smooth, so that the positive electrode active material layer 20 is formed. In addition to the surface of the material layer 20, lithium ions are inserted into the active material even at positions deep in the thickness direction of the positive electrode active material layer 20. In this way, the lithium ion secondary battery 10A is discharged.

  In the lithium ion secondary battery 10A according to the present embodiment, the first hole 26 is formed in the active material layer, so that lithium ions released from the active material at a position deep in the thickness direction from the surface of the active material layer can be obtained. It can move in the electrolyte. Therefore, in addition to the surface of the active material layer, even at a position deep in the thickness direction from the surface of the active material layer, electron transfer, ion insertion, and desorption occur, and the position deep from the surface of the active material layer in the thickness direction. The active material can be used effectively. Further, the moving distance of ions in the positive electrode 12A and the negative electrode 14A does not become too long, and the active material can be used more effectively and the capacity can be increased.

  In addition, since the second holes 28 are formed in the separator 16 and ions can pass through the separator 16 more smoothly, a decrease in charge / discharge capacity when charging / discharging at a high rate can be suppressed.

  Further, since the second hole 28 of the separator 16 is provided at a position overlapping the first hole 26 of the active material layer, ions can pass through the separator 16 more quickly, and charging / discharging when charging / discharging at a high rate. A decrease in capacity can be further suppressed.

Since lithium ions have a very small ion radius, it is considered that lithium ions are solvated with many solvents in the electrolytic solution. And the solvated lithium ion has a large movement resistance. Further, in the case of a conventional composite electrode formed by drying an electrode paste coated on the surface of a current collector and having no holes in the active material layer, an electrolyte solution containing LiPF ₆ as a lithium salt, for example, as a lithium salt PF ₆ ⁻ ions, which are counter ions when added to the electrolyte, migrated through the electrolyte contained in the micropores formed between the active materials in the electrodes.

Thus, in a lithium ion secondary battery using a conventional electrode in which the first hole 26 and the second hole 28 are not formed, solvated lithium ions (Li ⁺ ) and PF ₆ ⁻ ions are micropores. for the passage through the impregnated electrolyte, the lithium ion and PF ₆ ^- ions, easily caught by the micropores of the narrowed portion and the separator between the active materials, transfer resistance is increased further.

For contrast, in this embodiment, the separator 16, the second hole 28 is formed at a position corresponding to the first hole 26 formed in the active material layer, lithium-ion or PF ₆ ^- ions , It passes preferentially through the electrolyte present in the first hole 26 and the second hole 28. That is, the first hole 26 and the second hole 28 become a priority path through which ions can move quickly. Therefore, lithium ions can pass through the separator 16 without being inhibited. As described above, the lithium ion secondary battery 10A according to the present embodiment can obtain a high discharge capacity even when charging and discharging at a high rate.

  Further, in the lithium ion secondary battery 10 </ b> A, since the plurality of first holes 26 have the bottom portions 27, the liquid retaining property of the first holes 26 is improved. That is, even when the lithium ion secondary battery 10 </ b> A is tilted and the electrolyte is biased to one side, the electrolyte is held in the first hole 26. Therefore, the lithium ion secondary battery 10A can suppress a decrease in performance. Further, the positive electrode 12A and the negative electrode 14A are configured such that the current collectors 18 and 22 are not easily broken in the manufacturing process of the lithium ion secondary battery 10A by preventing the first hole 26 from penetrating the current collectors 18 and 22. The lithium ion secondary battery 10A can be manufactured efficiently.

(Modification)
The present invention is not limited to the above-described embodiment, and can be appropriately changed within the scope of the gist of the present invention.

  In the case of the said embodiment, although the 1st hole demonstrated the case where it was cylindrical shape, this invention is not limited to this. For example, like the lithium ion secondary battery 10B shown in FIG. 3, the first holes 32 formed in the active material layer 30 of the positive electrode 12B and the active material layer 34 of the negative electrode 14B may be conical. Moreover, although the 1st hole and the 2nd hole demonstrated the case where it was circular shape in planar view, this invention is not restricted to this, Ellipse shape and polygonal shape may be sufficient.

  Furthermore, the 1st hole and the 2nd hole do not need that all the 1st holes are the same magnitude | sizes and shapes, and the 1st hole with a different magnitude | size and shape may be mixed.

  The first hole has been described with respect to the case where the bottom is formed by the active material layer, but the present invention is not limited to this, and the bottom may be formed by a current collector. Since the bottom is formed by the current collector, the liquid retaining property of the first hole can be improved. The first hole may penetrate the active material layer and the current collector.

  Although the case where it applied to a lithium ion secondary battery was demonstrated as an electrical storage device, this invention is not restricted to this, You may apply to a lithium ion capacitor and an electrical double layer capacitor.

(Example)
An electrochemical cell was prepared by the procedure shown in the above production method, and the discharge capacity per unit mass was measured and evaluated. First, a positive electrode using LiCoO ₂ as an active material was prepared and applied to the positive electrode of an electrochemical cell.

First, LCO as an active material, PVDF as a binder, and acetylene black as a conductive additive were weighed so that the mass ratio was 90: 5: 5. Thereafter, the weighed PVDF was added to N-methyl-2-pyrrolidone (NMP) as a solvent and stirred for 20 minutes. Furthermore, LiCoO ₂ and acetylene black were added and stirred to obtain a positive electrode slurry.

  Next, an aluminum foil having a thickness of 15 μm was prepared as a current collector, and a positive electrode slurry was applied to one surface of the aluminum foil with a comma roll coater (product name: Chibi coater), at 120 ° C. for 1 hour. An active material layer was formed by drying. The thickness of the formed active material layer is 90 μm.

  Next, the aluminum foil on which the active material layer was formed was subjected to a roll press machine (manufactured by Sank Metal Co., Ltd., product name: 5 ton air hydro press) and compressed so that the thickness of the active material layer became 70 μm. Cut to a size of 25 mm x 35 mm.

  A sword-like needle was pierced on the surface of the active material layer to form a conical first hole having a center interval of 4 mm, a diameter of about 500 μm, and a depth of 100 μm. The positive electrode was produced through the above steps.

  Subsequently, a negative electrode using natural graphite as an active material was prepared and applied to the negative electrode of an electrochemical cell. First, natural graphite as an active material, SBR and CMC as a binder, and AB as a conductive additive were weighed so that the mass ratio was 97: 1: 1: 1. Thereafter, an aqueous solution containing the weighed CMC was prepared, and natural graphite, SBR and AB were added and stirred to obtain a negative electrode slurry.

  Next, a negative electrode slurry was applied as a current collector on a copper foil having a thickness of 10 μm using a comma roll coater (product name: Chibi coater) and dried at 110 ° C. for 1 hour to form an active material layer. did. The thickness of the formed active material layer is 90 μm.

  Next, the copper foil on which the active material layer was formed was subjected to a roll press machine (product name: 5 ton air hydro press, manufactured by Sank Metal Co., Ltd.) and compressed so that the thickness of the active material layer became 70 μm. Cut to a size of 25 mm x 35 mm. Finally, the same first hole as the positive electrode was formed on the surface of the active material layer. The negative electrode was produced through the above steps.

  As the separator, a polyethylene sheet material having a thickness of 20 μm was used. The separator was pierced with a sword-shaped needle to form a second through-hole having a center interval of 4 mm and a diameter of about 100 μm.

Position the second hole and the first hole, sandwich the separator, place the positive electrode on one side, the negative electrode on the other side, and mix 1M of EC and DEC in a volume ratio of 1: 1. the LiPF ₆ with the electrolyte solution added was inserted into an aluminum laminate pack, to produce a laminate cell of example and vacuum packed. As a comparative example, the same laminate cell as in the example was manufactured except that the second hole and the first hole were shifted by 2 mm.

  The characteristics of the electrochemical cell were evaluated by measuring the discharge capacity per unit mass. The discharge capacity was measured at a temperature of 25 ± 1 ° C. using a charge / discharge test apparatus (manufactured by Asuka Electronics Co., Ltd., model: ACD-R1APS).

  First, each capacitor was charged with CC (Constant Current) -CV (Constant Voltage) of 0.1C-4.2V. Here, 0.1 C is a charge rate for fully charging a charge capacity of up to 4.2 V in 10 hours. The battery was then discharged at a discharge rate of 0.1C. The above charge and discharge were repeated twice, and the discharge capacity when discharged at a discharge rate of 0.1 C for 10 hours was measured. In the third discharge, the discharge capacity when discharged at a discharge rate of 1 C for 1 hour was measured. As a result, in the case of 0.1 C discharge in which the electric capacity of the lithium ion secondary battery passed a current that can be discharged in 10 hours, the discharge capacities of the examples and comparative examples were both 145 (mAh / g).

  In the case of 1C discharge in which the electric capacity of the lithium ion secondary battery flows a current that can be discharged in 1 hour, a discharge capacity of 67 (mAh / g) was obtained in the example. On the other hand, the discharge capacity of the lithium ion secondary battery of the comparative example was 51 (mAh / g). In the case of 1C discharge, the discharge capacities of the examples and comparative examples are both lower than in the case of 0.1C discharge. The reason why the discharge capacity decreases when the discharge rate is high (in the case of a high rate) is considered to be due to the movement speed of lithium ions between the electrodes.

  In the lithium ion secondary battery of the example, the discharge capacity in the case of 1C discharge is larger than that of the lithium ion secondary battery in the comparative example, and the decrease in capacity during discharge at a high rate is suppressed. In the lithium ion secondary battery of the example, since the second hole formed in the separator is in a position overlapping the first hole formed in the active material layer, the lithium ion can pass through the separator more quickly. It is a factor.

  In the lithium ion secondary battery of the comparative example, since the second hole formed in the separator is located at a position shifted from the first hole formed in the active material layer, the movement of lithium ions is hindered. In this case, the discharge capacity was greatly reduced as compared with the example.

10A, 10B Lithium ion secondary battery 12A Positive electrode 14A Negative electrode 16 Separator 18, 22 Current collector 20 Positive electrode active material layer (active material layer)
24 Negative electrode active material layer (active material layer)
26, 32 First hole 27 Bottom 28 Second hole

Claims (6)

In an electricity storage device comprising a pair of electrodes and a separator provided between the pair of electrodes,
The pair of electrodes includes a current collector and an active material layer formed on a surface of the current collector,
The active material layer is provided with a plurality of first holes on the surface in contact with the separator,
The separator has a plurality of second holes;
The power storage device, wherein the second hole is located at a position overlapping the first hole. 2. The electric storage device according to claim 1, wherein the plurality of second holes have a diameter of 50 μm to 500 μm and a center interval of 1 to 5 mm. 3. The electricity storage device according to claim 1, wherein the plurality of first holes have a diameter of 200 μm to 700 μm and a depth of 20% or more of the thickness of the active material layer. The power storage device according to claim 1, wherein the plurality of first holes have a bottom portion formed of the current collector. 5. The electricity storage device according to claim 1, wherein an inner wall of the plurality of second holes has thermoplasticity. The electric storage device according to claim 1, wherein the first hole has a larger diameter than the second hole.

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