JP2015130245A - Power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device capable of improving supply performance of an electrolyte to an electrode, capable of improving the exhaustion of an electrolyte by the expansion and contraction of an electrode due to charging/discharging, and capable of suppressing deterioration in battery performance due to the exhaustion.SOLUTION: A power storage device 100 accommodates a positive electrode 1 and a negative electrode 3 within an exterior member 7, the positive electrode 1 and a negative electrode 3 being arranged to sandwich a porous separator 5 including a nonaqueous electrolyte 9, as an electrolyte, impregnated therein. The power storage device includes electrolyte reservoirs 20 surrounding a side peripheral part 1a of the positive electrode 1 and a side peripheral part 3a of the negative electrode 3, respectively.

Description

  The present invention relates to an electricity storage device.

  Power storage devices such as lithium ion batteries are used as power sources for mobile phones, notebook computers, electric vehicles, hybrid vehicles, and the like.

  The electric double layer capacitor disclosed in Patent Document 1 is configured by housing an electrode group in which porous separators are disposed between alternately stacked positive and negative electrodes and at both ends in the stacking direction in an outer case. The The separator partitions the positive electrode and the negative electrode, and also partitions the exterior case. For this reason, while ensuring the insulation of both electrodes, the insulation between exterior cases is also ensured.

  At the time of charging, ions such as anions and cations contained in the electrolytic solution impregnated in the separator are inserted into the electrodes (positive electrode and negative electrode) to expand the electrodes. Further, at the time of discharging, ions such as anions and cations contained in the electrolytic solution inserted into the electrode are released to the outside of the electrode, so that the electrode contracts.

  The expansion / contraction of the electrode mainly occurs in the stacking direction of the electrodes. For this reason, the electrolyte reservoir is disposed in the inner surface of the exterior case at a location corresponding to the electrode stacking direction. The electrolytic solution reservoir supplies the electrolytic solution to the separator when the electrode expands during charging, and compensates for the shortage of the electrolytic solution in the separator. In addition, the electrolyte reservoir absorbs the electrolyte overflowing from the separator when the electrode contracts during discharge, and prevents the electrolyte from overflowing from a discharge valve or the like provided in the exterior case.

JP 2007-220841 A

  In the configuration disclosed in Patent Document 1, the electrolyte reservoir is disposed outside the separator located at both ends of the electrode group. That is, the distance to the electrolyte reservoir is greatly different between the electrodes at both ends of the electrode group and the center electrode. For this reason, there is a problem that the supply amount of the electrolytic solution to the center electrode of the electrode group is smaller than the electrodes at both ends, and the performance of supplying the electrolytic solution to the electrodes is low. In addition, electrolyte depletion due to expansion / contraction of the electrode due to charge / discharge is locally expressed. It is considered that the depletion of the electrode solution is likely to occur at an electrode far from the electrolyte reservoir, such as the center electrode of the electrode group. The electricity storage device has a problem that when the electrolyte is depleted, the internal resistance increases, the capacity decreases, and the battery performance decreases.

  The present invention has been made to solve the above-described problems, and can improve the supply performance of the electrolyte solution to the electrode, can improve the depletion of the electrolyte solution due to the expansion / contraction of the electrode due to charge / discharge, and the battery due to the depletion It aims at providing the electrical storage device which can suppress the fall of performance.

In order to achieve the above object, an electricity storage device according to the present invention includes:
An electricity storage device in which a positive electrode and a negative electrode arranged in a case sandwiching a porous separator impregnated with an electrolytic solution are housed in a case,
An electrolyte reservoir is provided that surrounds a side periphery of at least one of the positive electrode and the negative electrode.

  According to the present invention, there is provided an electricity storage device that can improve the supply performance of an electrolyte solution to an electrode, can improve the depletion of the electrolyte solution due to the expansion / contraction of the electrode due to charge / discharge, and can suppress the decrease in battery performance due to the depletion be able to.

It is a block diagram of the electrical storage device which concerns on Embodiment 1 of this invention. (A) is a figure when the main surface of the positive electrode in the laminated body of an electrical storage device is seen, (b) is a figure which shows the lamination | stacking relationship of a part of laminated body of an electrical storage device, (c) is a part of laminated body It is sectional drawing. It is a block diagram of the electrical storage device of a comparative example. It is a figure which shows the capacity | capacitance change of the electrical storage device of an Example and a comparative example. (A)-(g) is a figure which shows the manufacturing method of the separator and electrolyte reservoir of Embodiment 3 of this invention. It is a block diagram of the electrical storage device which concerns on a modification. It is a block diagram of the electrical storage device which concerns on a modification. It is a block diagram of the electrical storage device which concerns on a modification.

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

(Embodiment 1)
As shown in FIG. 1, an electricity storage device 100 according to Embodiment 1 of the present invention includes a porous separator 5 interposed between alternately stacked positive electrodes 1 and negative electrodes 3, and The laminated body 6 in which the electrolyte reservoir 20 is disposed around the side peripheral portion 1a and the side peripheral portion 3a of the negative electrode 3 and the lithium ion supply source 15 are housed in the storage device cell 8. The positive electrode 1 is formed on the positive electrode current collector 2, and the negative electrode 3 is formed on the negative electrode current collector 4.

  The electricity storage device cell 8 has an exterior formed by an exterior member 7 as a case. The electricity storage device cell 8 is sealed with the nonaqueous electrolyte 9 filled therein. The non-aqueous electrolyte 9 is also filled in the laminate 6.

  The laminated body 6 is configured by stacking five layers including the negative electrode current collector 4 as the outermost layer and the positive electrode current collector 2 and the negative electrode current collector 4 through the separator 5. Specifically, the positive electrode 1 is formed on both surfaces of the positive electrode current collector 2. On the other hand, the negative electrode 3 is formed on one surface of the negative electrode current collector 4 positioned on the outermost layer (the surface facing the positive electrode 1) and on both surfaces of the negative electrode current collector 4 positioned on the inner side of the outermost layer. Yes. Since the separator 5 is interposed between the positive electrode 1 and the negative electrode 3, the positive electrode 1 and the negative electrode 3 are not in contact with each other.

  In FIG. 1, for easy understanding, the positive electrode 1, the negative electrode 3, the separator 5, and the electrolyte reservoir 20 are illustrated at intervals in the stacking direction, which are illustrated in FIG. 2 (c). In this way, they are in contact with each other in the stacked state and there is no gap in the stacking direction.

  Below, each structure of the electrical storage device 100 is demonstrated separately.

<Positive electrode 1>
The positive electrode 1 is formed on a positive electrode current collector 2 having a through-hole penetrating the front and back surfaces (main surfaces on both sides). The positive electrode 1 includes a carbon material (for example, artificial graphite) having a layered structure that can insert and desorb anions as a positive electrode active material. Ions such as anions and cations can pass through the through holes of the positive electrode current collector 2.

  The positive electrode current collector 2 has a main surface having a square shape (a square having a vertical and horizontal length W1 of 10 cm) as shown in FIG. 2 (a), and a thin plate shape as shown in FIG. 2 (b). The positive electrode current collector 2 has a thickness of 20 μm, and a positive electrode 1 having a square shape with a vertical and horizontal length W1 of 10 cm and a thickness of 80 μm is formed on both main surfaces. The positive electrode current collector 2 is connected to a long plate-shaped extraction electrode portion 10. As shown in FIG. 1, the two extraction electrode portions 10 are connected to the positive external terminal 16.

<Negative electrode 3>
The negative electrode 3 is formed on a negative electrode current collector 4 having a through-hole penetrating the front and back surfaces (main surfaces on both sides). Ions such as anions and cations can pass through the through holes of the negative electrode current collector 4. The negative electrode 3 includes a carbon material having a layered structure that can insert and desorb lithium ions as cations as a negative electrode active material. As the carbon material of the negative electrode 3, natural graphite, artificial graphite, non-graphitizable carbon, graphitizable carbon, low-temperature calcined carbon, activated carbon and the like are preferable.

  The negative electrode current collector 4 has a thin plate shape in which the main surface has a square shape (a square whose length W1 is 10 cm in length and width). The central negative electrode current collector 4 has a thickness of 15 μm, and a negative electrode 3 having a vertical and horizontal length W1 of 10 cm and a thickness of 90 μm is formed on the main surfaces on both sides. In the outermost negative electrode current collector 4, the negative electrode 3 having a square of 10 cm × 10 cm and a thickness of 90 μm is formed only on the main surface (one surface) facing inward. The negative electrode current collector 4 is connected to a long plate-shaped extraction electrode portion 11. As shown in FIG. 1, the three extraction electrode portions 11 are connected to the negative external terminal 17.

<Nonaqueous electrolyte 9>
The nonaqueous electrolytic solution 9 is an organic electrolytic solution in which an electrolyte (solute) containing a lithium salt is dissolved in an organic solvent. Moreover, other electrolytes may be included in addition to the lithium salt.

Lithium salts include LiPF ₆ , LiBF ₄ , LiCIO ₄ , LiN (CF ₃ SO ₂ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiCF ₃ SO ₃ , LiC (SO ₂ CF ₃ ) ₃ , LIAsF ₆ And one or more salts selected from the group consisting of LiSbF ₆ are preferred. In this embodiment, LiPF ₆ is used as the lithium salt. Further, the concentration of the lithium salt (electrolyte concentration) in the non-aqueous electrolyte 9 is preferably 0.5 to 5.0 mol / L (0.5 to 5.0 M), more preferably 1.0 to 1.5 mol / L. preferable.

  As the organic solvent, ethylene carbonate, butylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, sulfolane, dimethoxyethane and the like are preferable. These organic solvents may be used as a single solvent or as a mixed solvent of two or more. As the mixed solvent, a mixed solvent of ethylene carbonate and dimethyl carbonate is preferable, and a mixed solvent obtained by mixing ethylene carbonate and dimethyl carbonate at a weight ratio of 1: 1 is more preferable.

<Separator 5>
As shown in FIG. 1, the separator 5 is disposed between the positive electrode 1 and the negative electrode 3. The separator 5 is a porous film that prevents contact between the positive electrode 1 and the negative electrode 3, and is impregnated with a nonaqueous electrolytic solution 9 filled in the laminate 6. The separator 5 is, for example, a film having a thickness of about 50 μm and a porosity of about 70% from the viewpoint of permitting anion and cation ion permeation while ensuring insulation. The separator 5 is a porous film made of a cellulose polymer. The separator 5 may be a porous film made of a polyolefin-based polymer such as polyethylene.

<Exterior member 7>
The exterior member 7 forms an exterior of the electricity storage device cell 8. As the exterior member 7, for example, a laminate film made of aluminum is preferable.

<Electrolyte reservoir 20>
The electrolyte reservoir 20 can be impregnated with the non-aqueous electrolyte 9 filled in the laminate 6 and has a liquid retention property.

  The electrolyte reservoir 20 is made of the same material as the separator 5. That is, the electrolyte reservoir 20 is a porous film made of a cellulose polymer. Therefore, the porosity is about 70%. A porous film made of a polyolefin-based polymer such as polyethylene may also be used.

  As shown in FIG. 1 and FIG. 2B, the electrolyte reservoir 20 is disposed around the side peripheral portion 1 a of the positive electrode 1 and the side peripheral portion 3 a of the negative electrode 3, respectively.

  Specifically, the electrolyte reservoir 20 surrounding the side peripheral portion 1a of the positive electrode 1 has a square outer shape as shown in FIG. 2A, and a square-shaped opening 21 is formed at the center. As shown in FIG. The opening 21 has a size including the main surface region of the positive electrode 1. The electrolyte reservoir 20 surrounding the side periphery 3a of the negative electrode 3 also has a square outer shape, and a square-shaped opening 21 is formed at the center, and is arranged in two layers. The opening 21 also has a size including the main surface region of the negative electrode 3.

  As shown in FIG. 2A, the length W3 of each side of the opening 21 is larger than the vertical and horizontal lengths W1 of the positive electrode 1 and the negative electrode 3 (W3> W1). For this reason, the electrolytic solution reservoir 20 has a gap between the opening 21 and the side peripheral portion 1 a in a state where the positive electrode 1 or the negative electrode 3 is inserted into the opening 21. Thereby, it is easy to insert the positive electrode 1 and the negative electrode 3 into the opening portion 21, and the opening end portion of the opening portion 21 is not stacked in a state where the positive electrode 1 and the negative electrode 3 run over the positive electrode 1 and the negative electrode 3.

  Note that the length W3 of each side of the opening 21 may be, for example, a length at which the expanded positive electrode 1 and negative electrode 3 do not contact each other. In this case, even if the positive electrode 1 and the negative electrode 3 expand, the opening end portion of the opening 21 is not pressed by the positive electrode 1 and the negative electrode 3 and deformed in the thickness direction.

  The electrolyte reservoir 20 has a thickness of 50 μm per sheet, for example, and the total thickness becomes 100 μm by stacking two sheets. For this reason, the thickness (100 μm) of the two electrolyte reservoirs 20 is larger than the thickness of the positive electrode 1 (80 μm) and the thickness of the negative electrode 3 (90 μm). By doing so, the gap CL1 corresponding to the thickness of the positive electrode current collector 2 or the negative electrode current collector 4 shown in FIG. 2B and the gap CL2 between the separator 5 and the electrolyte reservoir 20 are changed into the positive electrode 1 and the negative electrode 3. In the stacked state of the separator 5 and the electrolyte reservoir 20, there can be no gap or a reduced gap as shown in FIG.

<Lithium ion source 15>
As shown in FIG. 1, the lithium ion supply source 15 is made of a metal foil 13 (for example, a copper foil) including a metal lithium 12 and is disposed inside the electricity storage device cell 8. An extraction electrode portion 14 is connected to the metal foil 13.

  Furthermore, the separator 5 is also disposed between the laminate 6 and the lithium ion supply source 15, between the laminate 6 and the exterior member 7, and between the lithium ion supply source 15 and the exterior member 7. Thereby, the laminated body 6, the lithium ion supply source 15, and the exterior member 7 do not contact each other.

  As described above, according to the electricity storage device 100 according to Embodiment 1 of the present invention, the electrolyte reservoir 20 is arranged so as to surround the side peripheral portion 1a of the positive electrode 1 and the side peripheral portion 3a of the negative electrode 3, respectively. It is installed. As a result, in addition to the nonaqueous electrolyte 9 impregnated in the separator 5 being supplied to the surfaces of the positive electrode 1 and the negative electrode 3, the nonaqueous electrolyte 9 impregnated in the electrolyte reservoir 20 is the positive electrode 1 and the negative electrode 3. To the side peripheral portions 1a and 3a. Therefore, the supply performance of the non-aqueous electrolyte 9 to the positive electrode 1 and the negative electrode 3 is improved. Further, the electrolyte reservoir 20 delivers and receives the nonaqueous electrolyte 9 to the side peripheral portions 1 a and 3 a of the positive electrode 1 and the negative electrode 3, and the electrolyte reservoir 20 delivers and receives the nonaqueous electrolyte 9 to the separator 5. Or For this reason, the depletion of the non-aqueous electrolyte 9 accompanying the expansion / contraction of the electrodes (the positive electrode 1 and the negative electrode 3) due to charge / discharge can be improved. Therefore, the electricity storage device 100 can suppress a decrease in battery performance, and can exhibit the battery performance for a longer period than in the past.

  The electrolyte reservoir 20 of the positive electrode 1 includes an opening 21 having a size including the main surface region of the positive electrode 1. The electrolyte reservoir 20 of the negative electrode 3 includes an opening 21 having a size including the main surface region of the negative electrode 3. For this reason, when the positive electrode 1 is inserted into the opening 21 of the electrolytic solution reservoir 20, the opening 21 of the electrolytic solution reservoir 20 surrounds the side peripheral portion 1a of the positive electrode 1 over the entire circumferential direction. When the negative electrode 3 is inserted into the opening 21 of the electrolyte reservoir 20 of the negative electrode 3, the opening 21 of the electrolyte reservoir 20 surrounds the side circumferential portion 3 a of the negative electrode 3 over the entire circumferential direction. Therefore, the non-aqueous electrolyte 9 can be efficiently exchanged between the electrolyte reservoir 20 and the side periphery 1a of the positive electrode 1 and between the electrolyte reservoir 20 and the side periphery 3a of the negative electrode 3.

  In addition, since the thickness of the electrolytic solution reservoir 20 is larger than the thickness of the electrode (positive electrode 1 or negative electrode 3), the electrolytic solution reservoir extends in the entire thickness direction of the side peripheral portion 1a of the positive electrode 1 and the side peripheral portion 3a of the negative electrode 3. 20 non-aqueous electrolytes 9 can be supplied, and the performance of supplying the non-aqueous electrolyte 9 to the electrodes can be improved.

  In addition, the dual carbon battery which is an example of the electricity storage device 100 uses a carbon material in which anions are inserted and desorbed between layers of a layered structure as a positive electrode active material of the positive electrode 1, and a layered structure of an interlayer A carbon material in which lithium ions are inserted as cations in advance while cations are inserted and desorbed is used. The positive electrode current collector 2 and the negative electrode current collector 4 include through holes that penetrate the main surfaces on both sides. The electrolyte used is a non-aqueous electrolyte 9 in which a lithium salt is dissolved. Also in the case of such a dual carbon battery, by using the electrolyte reservoir 20, the supply performance of the nonaqueous electrolyte 9 to the positive electrode 1 and the negative electrode 3 can be improved, and the positive electrode 1 and the negative electrode 3 can be expanded and charged by charging and discharging. It is possible to improve the depletion of the non-aqueous electrolyte 9 due to the shrinkage and to suppress the battery performance from being lowered.

  Here, the superiority or inferiority of the electrical performance of the electricity storage device 100 of the example having the electrolyte reservoir 20 shown in FIG. 1 and the electricity storage device 200 of the comparative example shown in FIG. Confirmed by

  The electricity storage device 100 of the example and the electricity storage device 200 of the comparative example were manufactured as follows.

<Preparation of electricity storage device 100 of example>
<Preparation of positive electrode 1>
The positive electrode 1 is a slurry (dispersion liquid) in which artificial graphite (KS6: manufactured by Timcal) is dispersed as a positive electrode active material in a solution in which polyvinylidene fluoride as a binder is dissolved in N-methyl-2-pyrrolidone as a solvent. The porous aluminum foil (commercial product; thickness: 20 μm, opening ratio: 20%), which is the positive electrode current collector 2, is applied to both main surfaces (front and back surfaces) using a doctor blade and dried. The thickness of the coated slurry after drying, that is, the thickness of one surface of the positive electrode 1 was 80 μm. The weight ratio of artificial graphite to polyvinylidene fluoride was 90:10.

<Preparation of negative electrode 3>
The negative electrode 3 is a slurry (dispersion) in which artificial graphite (MAGD; manufactured by Hitachi Chemical Co., Ltd.) is dispersed as a negative electrode active material in a solution obtained by dissolving polyvinylidene fluoride as a binder in N-methyl-2-pyrrolidone as a solvent. The negative electrode current collector 4 was coated with a doctor blade on both main surfaces (front and back surfaces) or one surface of a porous copper foil (commercially available product: thickness 15 μm, aperture ratio 40%) or one surface, and dried to form a negative electrode 3 Is made. The thickness of the coated slurry after drying, that is, the thickness of one surface of the negative electrode 3 was 90 μm. The weight ratio of artificial graphite to polyvinylidene fluoride was 90:10.

<Preparation of non-aqueous electrolyte 9>
Nonaqueous electrolyte 9 is a mixed solvent obtained by mixing ethylene carbonate and dimethyl carbonate at a weight ratio of 1: 1, lithium hexafluorophosphate (LiPF6) as a lithium salt, and its concentration (electrolyte concentration) is 1. It is prepared by dissolving to 5 mol / L (1.5 M).

<Preparation of separator 5>
The separator 5 is a porous film made of a cellulose-based polymer, and has a square outer shape with a length of W4 on each side and a thickness of 50 μm.

<Production of Electrolyte Reservoir 20>
The electrolyte reservoir 20 is a porous film made of a cellulose-based polymer, has a square outer shape with each side having a length W4, a square opening 21 is formed at the center, and the thickness is Made to 50 μm.

<Production of power storage device 100>
The electricity storage device 100 is manufactured under a dry atmosphere. First, the laminate 6 is formed by laminating five layers of the produced positive electrode 1 and negative electrode 3 through the separator 5 so that the outermost layer is the negative electrode 3, and the side periphery 1 a of the positive electrode 1 and the negative electrode 3 side. It is produced by arranging two electrolyte reservoirs 20 surrounding each of the peripheral portions 3a.

  Further, a commercially available lithium ion supply source 15 made of a metal foil 13 provided with metallic lithium 12 is laminated on the laminated body 6 via the separator 5 and accommodated in the exterior member 7. A non-aqueous electrolyte solution 9 was filled. Then, the cell 8 for electrical storage devices which sealed the exterior member 7 was produced.

  The negative electrode 3 and the extraction electrode portion 14 of the lithium ion supply source 15 are short-circuited through an external circuit (not shown) to cause the negative electrode 3 to occlude lithium ions. The current flowing through the short circuit line of the external circuit, which is generated by the process of ionizing lithium, is measured by, for example, a coulomb meter.

  The weight of the metallic lithium 12 is set to 70% by weight of the maximum weight (theoretical weight) of lithium ions that can be occluded by the negative electrode 3. That is, the amount of metallic lithium 12 disappears from the lithium ion supply source 15 at the end of occlusion. For this reason, it can be judged from the measured value of the coulomb meter that occlusion of lithium ions into the negative electrode 3 is completed.

  Next, a charge / discharge cycle was performed once, in which a constant current was passed between the positive electrode external terminal 16 and the negative electrode external terminal 17 until a voltage of 5.3 V was applied, followed by discharge.

  Through the above steps, the electricity storage device 100 according to Example 1 is manufactured.

<Production of Power Storage Device 200 of Comparative Example>
The electricity storage device 200 of the comparative example is manufactured by the same process as described above except that the electrolyte reservoir 20 of the first embodiment is not provided.

  The electricity storage device 100 of the example and the electricity storage device 200 of the comparative example were charged by 5C-CC (5 times the speed of 1C-CC) and 5C-CC discharge in a constant temperature bath at 25 ° C. in a voltage range of 3V to 5.3V. A charge / discharge cycle test of 100 cycles was performed. The capacity change after the charge / discharge cycle test of the electricity storage device 100 of the example and the electricity storage device 200 of the comparative example is shown in FIG. The capacity in FIG. 4 is a value when the initial stage before the test is “100”.

  As shown in FIG. 4, in the electricity storage device 100 of the example, the capacity after the cycle test is “100”, which is not changed. In the electricity storage device 200 of the comparative example, the capacity after the cycle test was reduced to “96”. That is, it turns out that the electrical storage device 100 of an Example has the outstanding effect that there is little capacity | capacitance fall even if charging / discharging is repeated. In the power storage device 200 of the comparative example, the factor that the capacity decrease is larger than that of the power storage device 100 of the embodiment is that the non-aqueous electrolyte 9 is locally depleted by repeating charge and discharge. This is thought to be due to a decrease in the effective utilization rate of the active material.

(Embodiment 2)
In the first embodiment, the electrolyte reservoir 20 has the same porosity as that of the separator 5, but in the second embodiment, a porous film having a higher porosity than the separator 5 is used. For example, the electrolyte reservoir 20 is a porous film having a porosity of 80% and is larger than the porosity (70%) of the separator 5.

  The separator 5 prevents a short circuit between the positive electrode 1 and the negative electrode 3. Therefore, the separator 5 needs to have a porosity that ensures insulation between the positive electrode 1 and the negative electrode 3. On the other hand, since the electrolyte reservoir 20 is not required to have insulating properties, the porosity can be made larger than the porosity of the separator 5. Therefore, in the second embodiment, the electrolyte reservoir 20 can be more liquid retaining than the separator 5, and the performance of supplying the non-aqueous electrolyte 9 to the electrode can be further improved.

(Embodiment 3)
Then, the electrical storage device 100 which concerns on Embodiment 3 of this invention is demonstrated. In the following description, the same reference numerals are given to components and the like that are common to the first embodiment.

  Even when the separator 5 and the electrolytic solution reservoir 20 are made of the same material, the separator 5 and the electrolytic solution reservoir 20 are usually made of different sheet bodies. The reason is as follows.

  The central portion of the electrolyte reservoir sheet is cut out larger than the main surface area of the positive electrode 1 or the negative electrode 3 to produce the electrolyte reservoir 20. Since the hollowed central portion is the same size as the positive electrode 1 or the negative electrode 3, it cannot be used as the separator 5. This central part is wasted. This is because the separator 5 having the same size as the positive electrode 1 or the negative electrode 3 cannot ensure insulation between the positive electrode 1 and the negative electrode 3.

  In contrast, in the third embodiment, as shown in FIG. 5, the separator 5 and the electrolyte reservoir 20 can be efficiently manufactured from the same sheet body 31. This manufacturing method will be described below.

  As shown in FIG. 5A, a square sheet 31 having a side W5 is cut out from a long sheet 30 indicated by a broken line having a width W5 (= W4 + 2 × W2).

  And the center body 32 shown in FIG.5 (b) is produced by cutting out into the square shape whose one side is length W4 (= W3 + 2 * W2) so that the center part of the sheet | seat body 31 may be shown with a dashed-dotted line. This central body 32 is used as the separator 5.

  As shown in FIG. 5C, a positive electrode current collector 2 on which a square positive electrode 1 having a side W1 is formed is disposed on the upper surface of the separator 5. On the lower surface of the separator 5, a negative electrode current collector 4 in which a square negative electrode 3 having a length W1 on one side is formed. The length W4 of each side of the separator 5 is larger than the length W1 of each side of the positive electrode 1. For this reason, since the separator 5 is larger than the main surface regions of the positive electrode 1 and the negative electrode 3, the insulation between the positive electrode 1 and the negative electrode 3 can be secured.

  As shown in FIG. 5 (d), the opening peripheral body 33 after cutting the central body 32 from the sheet body 31 is cut according to the cut line 34 shown by a one-dot chain line, and as shown in FIG. Two L-shaped divided bodies 35 and two L-shaped divided bodies 36 to be discarded are produced. The outer side of the L-shaped divided body 35 has a length W4.

  By combining the cut surfaces 34a of the two L-shaped divided bodies 35 shown in FIG. 5 (e), a combined peripheral body 37 shown in FIG. 5 (f) is produced. This combined peripheral body 37 is used as the electrolyte reservoir 20. The position and shape of the cut line 34 of the opening peripheral body 33 are determined so that the opening 21 is formed at the center when the two L-shaped divided bodies 35 are brought together at the cutting surface 34a. .

  As shown in FIG. 5 (f), the electrolyte reservoir 20 has a square outer shape with one side having a length W4. The central opening 21 is a square-shaped opening whose one side has a length W3 and is larger than the square-shaped positive electrode 1 and negative electrode 3 whose one side has a length W1. That is, the opening 21 is larger than the positive electrode 1 and the negative electrode 3.

  In this way, the separator 5 shown in FIG. 5C and the electrolyte reservoir 20 shown in FIG. 5F are produced from the single sheet body 31 shown in FIG. As shown in FIG. 5G, the separator 5 and the electrolyte reservoir 20 have the same external shape. The separator 5 is larger than the positive electrode 1 and the negative electrode 3. The electrolyte reservoir 20 on the positive electrode 1 side surrounds the side peripheral portion 1 a of the positive electrode 1 in a state where the positive electrode 1 is inserted into the opening 21. The electrolyte reservoir 20 on the negative electrode 3 side surrounds the side peripheral portion 1 a of the negative electrode 3 in a state where the negative electrode 3 is inserted into the opening 21.

  According to the third embodiment, the separator 5 is formed by the central body 32 obtained by cutting the central portion of the sheet body 31 larger than the main surface region of the positive electrode 1 or the negative electrode 3. In addition, the electrolyte reservoir 20 includes two L-shaped divided bodies 35 obtained by dividing the opening peripheral body 33 after the central body 32 is cut from the sheet body 31, and the side peripheral portion 1 a of the positive electrode 1 or the negative electrode 3. It is formed by a combined peripheral body 37 formed to have a size surrounding the side peripheral portion 3a. For this reason, the separator 5 and the electrolyte reservoir 20 can be efficiently manufactured from the single sheet member 31, and the portion that is wasted can be greatly reduced. Therefore, the productivity of the separator 5 and the electrolyte reservoir 20 can be improved.

  Note that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

  In Embodiment 1 described above, the positive electrode current collector 2 and the negative electrode current collector 4 in the multilayer body 6 are laminated in a total of five layers, but the present invention is not limited to this. For example, the positive electrode current collector 2 and the negative electrode current collector 4 may be laminated in two or more layers. In the case where three or more layers are laminated, the outermost layer of the laminate 6 is the negative electrode 3, so that the negative electrode 3 is positioned via the separator 5 with respect to the exterior member 7 and external stress is applied. However, the positive electrode 1 can be prevented from contacting the exterior member 7.

  In Embodiment 1 described above, artificial graphite is used as the negative electrode 3 as the negative electrode active material, but the present invention is not limited to this. For example, natural graphite may be used.

  In each of the above-described embodiments, two electrolyte reservoirs 20 are stacked, but may be one or three or more. Further, the thickness of the electrolyte reservoir 20 may be the same as or smaller than the thickness of the positive electrode 1 and the negative electrode 3.

  In the first embodiment described above, the porosity of the separator 5 and the electrolyte reservoir 20 is 70%, but is not limited to this value. For example, the porosity of the separator 5 and the electrolyte reservoir 20 may be a value within the range of 30 to 90%.

  Further, in the second embodiment described above, the porosity of the electrolyte reservoir 20 is 80% and the porosity of the separator 5 is 70%, but it is not limited to this value. It is preferable if the porosity of the electrolyte reservoir 20 is a value larger than the porosity of the separator 5.

  The power storage device 100 according to each embodiment described above includes the electrolyte reservoir 20 surrounding the side periphery 1a of the positive electrode 1 and the electrolyte reservoir 20 surrounding the side periphery 3a of the negative electrode 3. Only one of the electrolyte reservoirs 20 may be used.

  As shown in FIG. 6, only the electrolyte reservoir 20 surrounding the side peripheral portion 1a of the positive electrode 1 may be used. Moreover, as shown in FIG. 7, it is good also as only the electrolyte solution reservoir 20 surrounding the side peripheral part 3a of the negative electrode 3. FIG. 6 and 7, since the electrolyte reservoir 20 is also disposed inside the multilayer body 6, the electrical storage devices 100 </ b> A and 100 </ b> B are compared with the conventional electrical storage device in which the electrolyte reservoir is disposed only at both ends of the multilayer body. Thus, the supply performance of the non-aqueous electrolyte 9 to the positive electrode 1 or the negative electrode 3 is improved. Moreover, the depletion of the non-aqueous electrolyte 9 accompanying expansion / contraction of the positive electrode 1 or the negative electrode 3 due to charge / discharge can be improved.

  Further, the electrolyte reservoir 20 may be disposed so as to surround the side peripheral portions 1a and 3a of at least one electrode (positive electrode 1 or negative electrode 3) on the center side of the multilayer body 6.

  Further, as shown in FIG. 8, a plate-shaped electrolyte reservoir 40 may be disposed between the exterior member 7 and the separator 5 closest thereto. The electrolyte reservoir 40 may have, for example, the same shape as the separator 5 or a similar shape. Further, the electrolyte reservoir 40 may be disposed inside the metal foil 13 provided with the metal lithium 12.

  Further, the electrolyte reservoir 20 surrounding the side peripheral portion 1a of the positive electrode 1 completely surrounds the side peripheral portion 1a in the lateral circumferential direction, but may not surround a part of the side peripheral portion 1a in the lateral circumferential direction. Good. The electrolyte reservoir 20 surrounding the side peripheral portion 3a of the negative electrode 3 completely surrounds the side peripheral portion 3a in the lateral peripheral direction, but may not surround a part of the side peripheral portion 3a in the lateral peripheral direction.

  In each embodiment described above, the power storage device 100 is a dual carbon battery, but is not limited to this. For example, various secondary batteries such as a lithium ion battery, an electric double layer capacitor, and a lithium ion capacitor may be used. Moreover, it is good also as a structure which does not accommodate the metal lithium 12 in the cell 8 for electrical storage devices.

DESCRIPTION OF SYMBOLS 1 Positive electrode 1a Side peripheral part 2 Positive electrode collector 3 Negative electrode 3a Side peripheral part 4 Negative electrode collector 5 Separator 6 Laminate 7 Exterior member (case)
8 Electric storage device cell 9 Non-aqueous electrolyte (electrolyte)
DESCRIPTION OF SYMBOLS 10 Extraction electrode part 11 Extraction electrode part 12 Metal lithium 13 Metal foil 14 Extraction electrode part 15 Lithium ion supply source 16 External terminal for positive electrodes 17 External terminal for negative electrodes 20 Electrolyte reservoir 21 Opening part 30 Long sheet body 31 Sheet body 32 Center Body 33 Opening peripheral body 34 Cut line 34a Cut surface 35 L-shaped divided body (divided body)
36 L-shaped divided body (divided body)
37 Binding peripheral body 40 Electrolyte reservoir 100 Electric storage device 100A Electric storage device 100B Electric storage device

Claims (6)

An electricity storage device in which a positive electrode and a negative electrode arranged in a case sandwiching a porous separator impregnated with an electrolytic solution are housed in a case,
An electrolyte reservoir surrounding a side periphery of at least one of the positive electrode and the negative electrode;
An electricity storage device characterized by the above. The electrolyte reservoir includes an opening that surrounds the side periphery.
The power storage device according to claim 1. The positive electrode is formed by forming a material containing a positive electrode active material on a positive electrode current collector,
The negative electrode is formed on a negative electrode current collector by a material containing a negative electrode active material,
The thickness of the electrolyte reservoir is greater than the thickness of the electrode;
The electrical storage device according to claim 1 or 2, wherein The positive electrode active material is a carbon material from which anions are inserted and released,
The negative electrode active material is a carbon material in which cations are inserted and desorbed and lithium ions are inserted in advance as cations,
The positive electrode current collector and the negative electrode current collector include through holes penetrating the main surfaces on both sides,
The electrolytic solution is a non-aqueous electrolytic solution in which a lithium salt is dissolved.
The electricity storage device according to claim 3. The porosity of the electrolyte reservoir is greater than the porosity of the separator;
The electricity storage device according to any one of claims 1 to 4, wherein the electricity storage device is provided. The separator is formed by a central body obtained by cutting a central portion of a flat sheet body larger than a main surface region of the positive electrode or the negative electrode,
The electrolyte reservoir is formed in a size that surrounds the side peripheral portion by combining some of the plurality of divided bodies obtained by dividing the opening peripheral body after cutting the central body from the sheet body. Formed by a combined perimeter,
The electricity storage device according to any one of claims 1 to 4, wherein the electricity storage device is provided.

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