Organic electrolyte power storage device and method for manufacturing same

Abstract

The present invention provides: an organic electrolyte power storage device which is smaller than conventional organic electrolyte power storage devices and has a high electrode filling rate; and a method for manufacturing the same.　An organic electrolyte power storage device 10 comprises a plurality of electrodes 1 stacked together, a plurality of terminals 2 which are electrically connected to the plurality of electrodes 1, respectively, and an outer package 3 which is formed of an aluminum laminate film, wherein: each of the electrodes 1 has an effective part 1a that contributes to power storage and a lead part 1b to which the terminal 2 is connected; the lead part 1b and the terminal 2 are welded in the width direction of the terminal 2, and the width of the welded part is set to 0.15-0.8 mm; and the area Somm2 of the upper surface of the outer package 3, the area Semm2 of the effective part 1a of the electrode 1, and the thickness Tmm of the outer package 3 satisfy mathematical expressions (I) to (III).

Description

Organic electrolyte-based electricity storage device and method for manufacturing the same

[0001] The present invention relates to an organic electrolyte electricity storage device and a method for producing the same.

[0002] With the spread of the Internet of Things (IoT), wearable devices have been attracting increasing attention. Wearable devices have particularly high demands on power supply technology, and there is a demand for small, lightweight, high-energy-density, and fast-charging power storage devices. Examples of such power storage devices include organic electrolyte-based power storage devices such as lithium-ion batteries, electric double-layer capacitors, and lithium-ion capacitors.

[0003] An organic electrolyte-based electricity storage device generally has multiple electrodes stacked with an electrolyte sandwiched between them inside a sealed laminate film exterior, with tab leads (tab terminals) connected to the ends of each electrode for extracting electricity. In an electricity storage device configured in this way, when viewed from above, there are areas surrounding the area of ​​the electrode that contributes to electricity storage, including an area for connecting the electrode to the tab leads and an area for sealing the laminate film that constitutes the exterior. While the area for sealing the laminate film is essential for sealing the cell, it does not contribute to improving energy density. Therefore, from the perspective of miniaturization and weight reduction, it is desirable to make it as small as possible within the scope that ensures safety.

[0004] Therefore, a nonaqueous electrolyte secondary battery has been proposed in the past in which the ratio (X / Y) of the area X of the electrode group housing portion to the total area Y of the heat-sealed portion of the laminate film is set to 1.8 or less, thereby suppressing peeling of the sealed portion and achieving miniaturization (see Patent Document 1). In the secondary battery described in Patent Document 1, the width of the heat-sealed portion is preferably 2 to 10 mm.

[0005] Japanese Patent Application Laid-Open No. 2005-063856

[0006] There are strict demands for miniaturization of terminal equipment worn on the body, such as wearable devices, and further miniaturization of the energy storage devices installed in these devices is also required. Specifically, there is a demand to limit the overall size of the energy storage device to approximately 10 mm square. On the other hand, wearable devices are required to have high safety and high reliability. Therefore, from the viewpoint of ensuring safety, it is necessary to provide a large area for sealing the laminate film that constitutes the exterior body by fusing, and to prevent peeling of the laminate film. Similarly, from the viewpoint of ensuring reliability, it is desirable to provide a large welding area between the electrode and the tab lead to prevent lead breakage.

[0007] However, because a certain amount of area is required for heat-sealing the laminate film and welding the tab lead, miniaturizing the cell reduces the area that contributes to power storage, resulting in a problem of reduced energy density. Specifically, a width of approximately 5 to 10 mm is typically required for heat-sealing the laminate film, and a width of approximately 3 to 5 mm is typically required for welding the tab lead. For this reason, with the above-mentioned conventional technology, it is difficult to further reduce the overall size of the power storage device without reducing the energy density.

[0008] Therefore, an object of the present invention is to provide an organic electrolyte-based electricity storage device that is smaller than conventional devices and has a high electrode packing ratio, and a method for manufacturing the same.

[0009] The organic electrolyte solution-based electricity storage device according to the present invention comprises a plurality of electrodes stacked on top of one another, a plurality of terminals electrically connected to the plurality of electrodes, and an exterior body made of an aluminum laminate film, wherein the electrodes are provided with effective portions that contribute to electricity storage and lead portions to which the terminals are connected, the lead portions and the terminals are welded together in the width direction of the terminals, the width of the welded portion being 0.15 to 0.8 mm, and the area of ​​the top surface of the exterior body is So mm in plan view. ２ , the area of ​​the effective part of the electrode is S e mm ２ When the thickness of the exterior body is T mm, the following formulas 1 to 3 are satisfied.

[0010]

[0011]

[0012]

[0013] In the organic electrolyte-based electricity storage device of the present invention, the lead portion and the terminal may be ultrasonically welded in the width direction of the terminal, and the width of the weld may be 0.15 to 0.8 mm. Furthermore, the multiple electrodes may be composed of a positive electrode having a positive electrode active material applied to its effective portion and a negative electrode having a negative electrode active material applied to its effective portion, and the positive electrode active material and the negative electrode active material may be active materials capable of absorbing and desorbing ions. In this case, the positive electrode active material and the negative electrode active material may contain a composite material of graphene and carbon nanotubes. Alternatively, the multiple electrodes may be composed of a positive electrode having a positive electrode active material applied to its effective portion and a negative electrode having a negative electrode active material applied to its effective portion, and the positive electrode active material may be an active material capable of absorbing and desorbing ions, and the negative electrode active material may be an active material capable of absorbing and desorbing lithium ions, and the negative electrode active material may be pre-doped with lithium ions. In this case, the positive electrode active material may contain a composite material of graphene and carbon nanotubes.

[0014] A method for manufacturing an organic electrolyte solution-based electricity storage device according to the present invention includes the steps of stacking a plurality of electrodes, each of which has an effective portion that contributes to electricity storage and a lead portion to which a terminal is connected, connecting terminals to the plurality of electrodes, and sealing the stacked electrodes to which the terminals are connected with an exterior body made of an aluminum laminate film, and the area of ​​the top surface of the exterior body is set to So mm in plan view. ２ , the area of ​​the effective part of the electrode is S e mm ２ When the thickness of the exterior body is T mm, an electricity storage device that satisfies the above formulas 1 to 3 is obtained. The step of connecting terminals to the plurality of electrodes may involve ultrasonic welding in the width direction of the terminals using an ultrasonic welding device that includes a holding portion that holds the objects to be welded, an anvil, and a horn, so that the width of the weld is 0.15 to 0.8 mm.

[0015] According to the present invention, it is possible to realize an organic electrolyte-based electricity storage device that is ultra-compact and has a high electrode packing ratio.

[0016] 1 is a plan view showing an example of the configuration of an organic electrolyte solution-based electricity storage device according to an embodiment of the present invention; FIG. 2 is a perspective view showing the internal structure of the electricity storage device 10 shown in FIG. 1; and FIG. 3 is a flowchart showing an example of a manufacturing method for an organic electrolyte solution-based electricity storage device according to an embodiment of the present invention. A diagram schematically showing a process of applying a slurry to a metal foil and pressing it. A diagram schematically showing a process of cutting out electrodes from a metal foil on which an active material layer has been formed. A diagram schematically showing a process of stacking electrodes. A diagram schematically showing a method of alignment in the process of stacking electrodes. A diagram schematically showing a process of ultrasonically welding terminals to lead portions of electrodes. A to C are diagrams schematically showing an example of the configuration of a horn 43 of an ultrasonic welding device 40, where A is a front view, B is a bottom view, and C is a right side view. A diagram is a cross-sectional view schematically showing a process of folding back an aluminum laminate film after heat fusion. A to C are cross-sectional views showing a method of processing the ends of an exterior body in an electricity storage device according to an embodiment of the present invention, where A shows one fold, B shows two folds, and C shows a fold.

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes in detail the preferred embodiments of the present invention, but the present invention is not limited to the following preferred embodiments.

[0018] (Configuration of electricity storage device) Fig. 1 is a plan view showing an example of the configuration of an organic electrolyte-based electricity storage device (hereinafter also simply referred to as "electricity storage device") according to an embodiment of the present invention, and Fig. 2 is a perspective view showing the internal structure of the electricity storage device 10 shown in Fig. 1. The electricity storage device 10 of this embodiment is an organic electrolyte-based electricity storage device such as an electric double layer capacitor, a lithium ion capacitor, or a lithium ion battery, and has a plurality of electrodes 1, a plurality of terminals 2, and an exterior body 3, as shown in Figs. 1 and 2 .

[0019] [Electrode 1] In the electricity storage device 10 of this embodiment, a plurality of electrodes 1 are stacked with separators or the like interposed therebetween, and an organic electrolyte solution is filled between each electrode 1. The electrode 1 is composed of a current collector made of a metal foil or the like, and an active material layer formed on the current collector. For example, an electrode (positive electrode) in which a positive electrode active material is applied to a current collector and an electrode (negative electrode) in which a negative electrode active material is applied to a current collector are alternately stacked.

[0020] When the electricity storage device 10 of the present embodiment is an electric double layer capacitor, active materials capable of absorbing and desorbing ions can be used for the positive electrode active material and the negative electrode active material constituting the electrode 1. In this case, from the viewpoint of improving the energy density, it is preferable that part or all of the positive electrode active material and the negative electrode active material be a composite material of graphene and carbon nanotubes.

[0021] Furthermore, when the power storage device 10 of this embodiment is a lithium ion capacitor, the positive electrode active material may be an active material capable of absorbing and desorbing ions, and the negative electrode active material may be an active material capable of absorbing and releasing lithium ions, and it is preferable that the negative electrode active material is pre-doped with lithium ions. In this case, from the viewpoint of improving energy density, it is preferable that part or all of the positive electrode active material is a composite material of graphene and carbon nanotubes.

[0022] Each electrode 1 is provided with an effective portion 1a that contributes to electricity storage and a lead portion 1b to which a terminal 2 is connected, and the above-mentioned active material layer is formed only on the effective portion 1a, not on the lead portion 1b. The shapes of the effective portion 1a and the lead portion 1b are not particularly limited and can be set appropriately depending on the specifications of the electricity storage device. For example, in the case of an electricity storage device that is approximately rectangular in plan view as shown in Fig. 1, from the viewpoints of miniaturization and energy density, the effective portion 1a may also be rectangular, and the lead portion 1b may be formed to protrude from one side of the current collector.

[0023] [Terminal 2] As shown in Figures 1 and 2, the terminal 2 is connected to the lead portion 1b of the electrode 1 using, for example, ultrasonic welding. The aluminum laminate film constituting the exterior body 3 is sealed at a location that includes the weld 5 between the terminal 2 and the lead portion 1b. Therefore, a wide width W of the weld 5 hinders an improvement in the packing density. For this reason, the terminal 2 is preferably welded in its width direction so that the width W of the weld 5 is in the range of 0.15 to 0.8 mm. This allows the charging device to be miniaturized while maintaining the packing density and weld strength. The length L of the weld 5 can be selected appropriately depending on the width of the terminal 2.

[0024] [Exterior Body 3] The exterior body 3 is formed from an aluminum laminate film (a thermoplastic resin film such as polyethylene laminated onto aluminum foil or aluminum vapor-deposited film), one side of which is folded, and the other three sides are sealed by a method such as heat sealing.

[0025] Here, an index called "filling rate" is introduced to quantify the size reduction of the electricity storage device. Specifically, the area So mm of the top surface of the exterior body 3 in a plan view is ２ The area of ​​the effective part 1a of the electrode 1 is S e mm ２ The ratio (=(Se / So)×100) is defined as the filling rate (%). In an electricity storage device, in order to increase the energy density of the cell, it is preferable that the above-mentioned filling rate value is high.

[0026] Therefore, in the electricity storage device 10 of this embodiment, the area So mm ２ The area of ​​the effective part 1a of the electrode 1 is S e mm ２ The ratio (Se / So) satisfies the following formula 4, and the area So of the upper surface of the exterior body 3 is 60 mm ２ Super 170mm ２ and the thickness T of the exterior body 3 is set to 3.0 mm or less. This makes it possible to reduce the size of the electricity storage device while maintaining a high energy density.

[0027]

[0028] [Manufacturing Method] Next, a description will be given of a manufacturing method for the above-mentioned organic electrolyte solution-based electricity storage device 10. The manufacturing method for the electricity storage device 10 of this embodiment includes the steps of stacking a plurality of electrodes 1 on each other, each of which has at least an active portion 1 a that contributes to electricity storage and a lead portion 1 b to which a terminal 2 is connected, connecting the terminal 2 to the plurality of stacked electrodes 1, and sealing the stacked electrodes 1 to which the terminal 2 is connected with an exterior body 3 made of an aluminum laminate film.

[0029] 3 is a flowchart showing an example of a method for manufacturing the organic electrolyte-based electricity storage device of this embodiment. More specifically, the electricity storage device 10 of this embodiment can be manufactured by performing steps S1 to S8 shown in FIG.

[0030] [First Step: Slurry Coating and Pressing Step S1] In the first step, a slurry containing an active material is coated on both sides of a metal foil that functions as a current collector, and then the coated surface is pressed under pressure. Here, an aluminum foil or the like can be used as the metal foil. The slurry can also be prepared by blending the active material with a binder and a solvent such as water.

[0031] 4 is a diagram schematically illustrating a process of applying a slurry to a metal foil and pressing the metal foil. The first process (slurry application / pressing process S1) can be performed, for example, by an apparatus 30 including a nozzle 31 and a press roll 32 as shown in FIG. 4. Specifically, the slurry 20 is intermittently ejected from the nozzle 31 of the application / pressing apparatus 30, and the slurry 20 is applied to both sides of the metal foil 20 at a predetermined width and at a constant interval.

[0032] Then, after drying the slurry 21 as necessary, it is pressed with a pair of press rolls 32 to form an active material layer 22 on the metal foil 20. In this case, the length of the region where the slurry 21 is applied can be, for example, 15 mm, and the length of the region where it is not applied (application interval) can be 10 mm. Furthermore, it is preferable that the deviation (alignment accuracy) between the active material layer 22 formed on the front side and the active material layer 22 formed on the back side is 0.2 mm or less.

[0033] While Figure 4 shows an example in which the slurry 21 is applied using a nozzle 31, the present invention is not limited to this. A transfer method can also be used in which a pair of rolls are arranged close to each other and the slurry applied to one roll is transferred to the other roll. In this case, the slurry is intermittently applied to one side of the metal foil, and the position is detected by a sensor. The front and back surfaces can be aligned by adjusting the timing of moving the pair of rolls closer to or further apart. Furthermore, by adjusting the transport speed of the metal foil, it is possible to prevent the slurry from being applied to a uniform thickness, thereby forming an active substance layer with a uniform thickness.

[0034] [Second step: electrode cutting step S2] Fig. 5 is a diagram schematically showing a step of cutting out an electrode 1 from a metal foil 20 on which an active material layer 22 has been formed. In the second step (electrode cutting step S2), as shown in Fig. 5, an electrode 1 is cut out from the metal foil 20, the electrode 1 comprising an effective portion 1a in which the active material layer 22 has been formed on the metal foil 20, and a lead portion 1b made up of only the metal foil 20. Note that when the active materials of the positive electrode and the negative electrode are different, the second step described above is performed for each of the positive electrode and the negative electrode.

[0035] [Step 3: Electrode Lamination Step S3] In the third step (electrode lamination step S3), electrodes of different polarities are alternately laminated on the multiple electrodes 1 cut out in step 2, with the positions of the effective portions aligned. Negative electrodes and positive electrodes are alternately laminated. Fig. 6 is a diagram schematically illustrating the step of laminating electrodes, and Fig. 7 is a diagram schematically illustrating a method of alignment in the step of laminating electrodes.

[0036] Specifically, as shown in Figures 6 and 7, positive electrodes 11 each having a positive electrode active material layer 6 formed on both sides of a current collector 5 and negative electrodes 12 each having a negative electrode active material layer 7 formed on both sides of a current collector 5 are alternately stacked with separators 8 interposed therebetween. In this case, the positions of the lead portions 1b of the electrodes 1 having the same polarity are the same, and the positions of the lead portions 1b of the electrodes 1 having opposite polarities are different, and the lead portions 1b of the positive electrodes 11 and the negative electrodes 12 are arranged in positions where they do not overlap each other. The number of electrodes 1 to be stacked is not particularly limited, and there may be one positive electrode 11 and one negative electrode 12, or multiple electrodes.

[0037] [Fourth Step: Terminal Welding Step S4] In the fourth step (terminal welding step S4), terminals 2 are welded to the lead portions 1b of the electrodes 1 stacked in the third step, with the electrodes 1 stacked in the same polarity. Fig. 8 is a diagram schematically showing the step of ultrasonically welding terminals to the lead portions of the electrodes. The welding of the terminals 2 can be performed, for example, by an ultrasonic welding device 40 including a holding portion 41, an anvil 42, and a horn 43 shown in Fig. 8.

[0038] When ultrasonic welding is performed using an ultrasonic welding device 40, first, the lead portions 1b are aligned by a holding portion 41, and multiple electrodes 1 are held with the terminals 2 overlapping. Next, the lead portion 1b of, for example, the positive electrode 11 is overlapped on a terminal 2 placed on an anvil 42, and is then clamped between the anvil 42 and a horn 43 disposed above it. Then, pressure is applied to the contact portion between the lead portion 1b and the terminal 2 by the horn 43, and welding is performed at a relatively low temperature by ultrasonic vibrations applied to the horn 43 from a drive source (not shown). In this embodiment, the region to which the ultrasonic vibrations are applied from the horn 43 is referred to as a welding region 44, which is distinguished from the welded portion 4 formed as a result of welding the lead portion 1b and the terminal 2.

[0039] The anvil 42 of the ultrasonic welding device 40 is a frustum-shaped receiving jig, and the surface (top surface) that contacts the workpiece is wider than the intended welding area. The horn 43 also has multiple protrusions that contact the workpiece. Figure 9 is a schematic diagram showing an example configuration of the horn 43 of the ultrasonic welding device 40, with Figure 9A being a front view, Figure 9B being a bottom view, and Figure 9C being a right side view. As shown in Figures 9A-C, the horn 43 has multiple protrusions 43a on a flat area that also has a large welding area 44. For example, good ultrasonic welding can be achieved by using a horn 43 whose welding area 44 is 0.2 mm wide and 1 mm long.

[0040] The horn 43 has a reinforcing portion extending from the flat region at a position away from the protrusion 43a on the opposite side from the holding portion 41. The side of the horn 43 facing the holding portion 41 is cut off at an acute angle to prevent interference with the holding portion 41. However, reducing the area of ​​the welding region 44 would result in insufficient strength for the horn 43. Therefore, providing a reinforcing portion on the side that does not interfere with the support portion 41 improves strength. This allows the width W of the welding portion 4 to be reduced and the packing rate to be increased, thereby enabling the miniaturization of the electricity storage device 10. The shapes of the anvil 42 and the horn 43 are not limited to those shown in FIGS. 8 and 9 and can be modified as appropriate depending on the specifications of the electricity storage device 10.

[0041] 8, the lead portions 1b of the electrodes 1 are overlapped in the same position with the same shape, but the present invention is not limited to this, and the lead portions 1b may be arranged so as not to overlap each other. This results in one terminal 2 being connected to one electrode 1, thereby improving the welding strength. Furthermore, even if the welded portion peels off due to deterioration over time, the poor connection does not affect other electrodes, preventing a sudden and significant deterioration in the performance of the electricity storage device 10, i.e., the electricity storage capacity.

[0042] [Fifth Step: Laminate Film Heat-Fusing Step S5] In the fifth step (laminate film heat-fusing step S5), as shown in FIG. 2 , the electrode 1 connected to the terminal 2 is placed on a laminate film that will become the exterior body 3, and the laminate film is folded back to cover the electrode 1. In this state, the edges of the laminate film that are perpendicular to the folded back side are heat-fused. In the energy storage device 10 shown in FIG. 1 , the bottom side is the folded back side, and the right and left sides are the sides that are heat-fused in the fifth step. Note that by folding back one side, the side that is heat-fused can be reduced, thereby reducing the excess area of ​​the cell and improving the packing rate.

[0043] Conventionally, the required width of the heat fusion was about 5 to 10 mm around the periphery of the electrode, but in the manufacturing method of the electricity storage device of this embodiment, by applying a two-stage heat fusion method, it is possible to reduce this to 2 mm. Here, the two-stage heat fusion method is a fusion method consisting of a first stage in which the fused portion is fixed by heat fusion at a low temperature, and a second stage in which the fused portion is precisely adjusted and reinforced by fusion at a high temperature.

[0044] In the electricity storage device 10 of this embodiment, the fused portion of the aluminum laminate film may be further folded inward. FIG. 10 is a cross-sectional view schematically illustrating the process of folding back the aluminum laminate film after heat fusion. As shown in FIG. 10, by folding the heat fused portion, the excess area on the left and right sides can be reduced, thereby increasing the packing ratio. Note that in the view after folding shown in FIG. 10, the folded portion of the aluminum laminate film (exterior body 3) and the portion covering the stacked electrode 1 are separated, but it is preferable to fold them so that they are as close as possible.

[0045] [Sixth Step: Drying Step S6] In the sixth step (drying step S6), the electrode 1 enclosed in the exterior body 3 is dried.

[0046] [Seventh Step: Electrolyte Solution Impregnation Step S7] In the seventh step (electrolyte solution impregnation step S7), an organic electrolyte solution is injected into the exterior body 3.

[0047] [Eighth Step: Vacuum Heat-Fusing Step S8] In the eighth step (vacuum heat-fusing step S8), the open side is heat-fused while the interior of the exterior body 3 is evacuated and reduced in pressure. At this time, the electrode 1 and the welded portion 5 of the terminal 2 are sealed within the exterior body 3, and the portion of the terminal 2 other than the welded portion 5 is pulled out of the exterior body 5.

[0048] As described above in detail, in this embodiment, the packing rate is increased, so that the electricity storage device can be miniaturized while maintaining a high energy density. As a result, an organic electrolyte electricity storage device that is ultra-compact yet has a high energy density can be realized.

[0049] The effects of the present invention will be specifically described below with reference to examples and comparative examples. Figures 11A to 11C are cross-sectional views showing methods for processing the edges of the exterior body of an electricity storage device according to an example of the present invention, with Figure 11A showing one fold, Figure 11B showing two folds, and Figure 11C showing a fold. In this example, electricity storage devices according to the example and comparative example were produced using the methods and conditions shown below, and their electrical characteristics were evaluated.

[0050] <Example 1> (1) Preparation of a positive electrode ２ 87 parts by mass of YP-50 activated carbon powder having a particle diameter D50 of 5 μm, 87 parts by mass of acetylene black powder, 5 parts by mass of an acrylic binder, 4 parts by mass of carboxymethyl cellulose, and 210 parts by mass of water were blended and thoroughly mixed to obtain a positive electrode slurry.

[0051] The positive electrode slurry prepared by the above method was intermittently coated on both sides of a positive electrode current collector made of 22 μm-thick etched aluminum foil using a roll coater. The coating length was 10 mm, and the coating interval was 10 mm. This was vacuum-dried to form a positive electrode active material layer, resulting in a positive electrode having a total thickness of 82 μm, which was the sum of the thickness of the positive electrode active material layers on both sides and the current collector.

[0052] (2) Preparation of Negative Electrode A negative electrode was prepared in the same manner and under the same conditions as those for the positive electrode.

[0053] (3) Cell Preparation Ten positive electrodes measuring 6.5 mm x 6.2 mm were cut out from the positive electrode, and eleven negative electrodes measuring 6.5 mm x 6.2 mm were cut out. These positive and negative electrodes were alternately stacked with separators interposed between them. Further separators were placed on the top and bottom of the stack, and the four sides were taped to obtain an electrode stack unit. In this electrode stack unit, aluminum terminals (2 mm wide, 0.1 mm thick) were placed on the lead portions of the positive and negative electrode current collectors and ultrasonically welded. The size of the weld was 0.2 mm wide and 1.0 mm long.

[0054] After drying at 120°C for 12 hours, the exterior laminate film was folded back with the terminal ends pulled out, and both sides of the exterior laminate film were heat-sealed with a sealing width of 2 mm. EMI-BF4 (1-ethyl-3-methylimidazolium tetrafluoroborate) was then injected into the exterior body as an electrolyte, and the electrodes were vacuum-impregnated. The open top edge was then heat-sealed with a sealing width of 2 mm under reduced pressure, resulting in a vacuum-sealed exterior. Then, as shown in FIG. 11A, both sides were folded back once to produce an electric double layer capacitor (EDLC) cell with an exterior size of 12.8 mm long, 10.2 mm wide, and 2.492 mm thick.

[0055] (4) Filling rate, etc. The filling rate of the cell of Example 1 produced by the above-described method is calculated as follows: Area of ​​the upper surface of the exterior body: So (Xo × Yo) = 12.8 mm × 10.2 mm = 130.56 mm ２Area of ​​effective portion 1a: Se (Xe × Ye) = 6.5 mm × 6.2 mm = 40.3 mm ２ Filling rate: Se / So×100=40.3 / 130.56×100=30.9% Here, 0.2978lnSo−1.2088=0.242, so the cell of Example 1 satisfies formula (I) of claim 1. In addition, the area So and thickness T of the upper surface of the exterior body also satisfy formulas (II) and (III) of claim 1, respectively, and the cell of Example 1 satisfies the requirements defined in claim 1.

[0056] (5) Electrical Characteristics of the Cell The electrochemical characteristics of the cell were measured using a multichannel potentio / galvanostat (VMP-300 manufactured by Bio-Logic Science Instruments). Specifically, the cell was charged at a constant current of 0.2 A / g per unit mass of the electrode membrane active material until the cell voltage reached 2.7 V, and then discharged at a constant current of 0.2 A / g per unit mass of the electrode membrane active material until the cell voltage reached 2.7 V. The initial capacitance was then determined from the discharge curve between the voltage Vmax at the start of discharge and the voltage 0 V at the end of discharge.

[0057] To evaluate durability, a voltage of 2.7 V was applied to the cell at a temperature of 65°C, and the capacitance after 2000 hours was determined by simulation, and the capacitance retention was calculated. As a result, the capacitance after 2000 hours was 0.55 F compared to the initial capacitance of 0.57 F, and the capacity retention was 97.1%, indicating favorable results.

[0058] Example 2 An electric double layer capacitor (EDLC) cell was fabricated using the same method and conditions as in Example 1, except that the sealing width on the left and right sides of the exterior laminate film was set to 1.5 mm. The cell of Example 2 had the same area So of the upper surface of the exterior body, the area Se of the active portion 1a, and the thickness T of the exterior body as in Example 1, and satisfied the requirements defined in claim 1. The filling rate was also 30.9%, the same as in Example 1.

[0059] Furthermore, when the electrical characteristics of the cell of Example 2 were measured in the same manner as in Example 1, the capacitance after 2000 hours was 0.54 F compared to the initial capacitance of 0.57 F, and the capacity retention was 94.7%. Although the capacity retention of the cell of Example 2 was slightly lower than that of the cell of Example 1, good results were obtained.

[0060] Example 3 An electric double layer capacitor (EDLC) cell was produced in the same manner and under the same conditions as in Example 1, except that the sealing width on the left and right sides of the exterior laminate film was set to 3.0 mm and the left and right sides were folded twice as shown in Figure 11B. The cell of Example 3 had the same area Se of the active portion 1a and thickness T of the exterior body as in Example 1, but the area So of the upper surface of the exterior body was 135.68 mm ２ Since the cell size increased to 12.8 mm x 10.6 mm, the packing ratio was 29.7%, which was slightly lower than that of the cell of Example 1.

[0061] In addition, since 0.2978lnSo-1.2088=0.253, the cell of Example 3 also satisfies formula (I) of claim 1. Furthermore, the area So and thickness T of the upper surface of the exterior body also satisfy formulas (II) and (III) of claim 1, respectively, so the cell of Example 3 satisfies the requirements defined in claim 1.

[0062] Next, the electrical characteristics of the cell of Example 3 were measured using the same method and conditions as in Example 1. The capacitance after 2000 hours was 0.56 F, compared to the initial capacitance of 0.57 F, and the capacity retention was 98.2%. As a result, the cell of Example 3 had an improved capacity retention compared to the cell of Example 1, and good results were obtained.

[0063] Example 4 An electric double layer capacitor (EDLC) cell was fabricated using the same method and conditions as in Example 1, except that the sealing width on the left and right sides of the exterior laminate film was set to 5.0 mm and the left and right sides were folded back to the top surface of the exterior body as shown in Figure 11C. The cell of Example 4 had an increased exterior body thickness T of 2.71 mm, but the area So of the top surface of the exterior body and the area of ​​the effective portion 1a were the same as those of the cell of Example 1, and the packing ratio was also the same as that of the cell of Example 1, at 30.9%. Therefore, the cell of Example 4 satisfied the requirements defined in claim 1 for the area So of the top surface of the exterior body, the area Se of the effective portion 1a, and the thickness T of the exterior body.

[0064] Next, the electrical characteristics of the cell of Example 4 were measured using the same method and conditions as in Example 1. The capacitance after 2000 hours was 0.566 F, compared to the initial capacitance of 0.57 F, and the capacity retention was 99.3%. As a result, the cell of Example 4 had an improved capacity retention compared to the cell of Example 1, and good results were obtained.

[0065] Example 5 In Example 5, a film-type capacitor cell was produced using a positive electrode and a negative electrode manufactured by changing the active material from activated carbon powder to a carbon nanotube / graphene composite (CNT / G).

[0066] (1) Preparation of Positive Electrode and Negative Electrode The preparation method and conditions for the positive electrode and negative electrode were the same as those in Example 1, except that the active material was changed. The total thickness of the electrodes, which was the sum of the thicknesses of the active material layers on both sides and the current collector, was 92 μm.

[0067] (2) Cell Fabrication Cells were fabricated using the same method and conditions as in Example 1, except that the number of positive electrodes was 11 and the number of negative electrodes was 12. In the cell of Example 5, the thickness T of the exterior body was increased to 2.94 mm, but the area So of the upper surface of the exterior body and the area of ​​the effective portion 1a were the same as those of the cell of Example 1, and the packing rate was also 30.9%, the same as that of the cell of Example 1. Therefore, the area So of the upper surface of the exterior body, the area Se of the effective portion 1a, and the thickness T of the exterior body all satisfied the requirements defined in claim 1.

[0068] (3) Electrical Characteristics of the Cell Next, the electrical characteristics of the cell of Example 5 were measured using the same method and conditions as in Example 1. The capacitance after 2000 hours was 1.59 F, compared to the initial capacitance of 1.63 F, and the capacity retention was 97.7%. As a result, the cell of Example 5 had a capacitance that was more than three times higher than that of the cells of Examples 1 to 4, which used activated carbon powder as the active material, and also had a capacity retention rate that was equal to or higher than that of the cells of Examples 1 to 4, and thus good results were obtained.

[0069] Example 6 A film-type capacitor cell was fabricated using the same method and conditions as the cell of Example 5, except that the number of positive electrodes was seven and the number of negative electrodes was eight. The cell of Example 6 had a thinner exterior body thickness T of 2.00 mm compared to the cell of Example 5, but the area So of the upper surface of the exterior body and the area of ​​the effective portion 1a were the same, and the filling factor was also the same, 30.9%. Therefore, the cell of Example 6 satisfied the requirements defined in claim 1 for the area So of the upper surface of the exterior body, the area Se of the effective portion 1a, and the thickness T of the exterior body.

[0070] Next, the electrical characteristics of the cell of Example 6 were measured using the same method and conditions as in Example 1. The capacitance after 2000 hours was 1.01 F, and the capacity retention was 97.4%, compared to the initial capacitance of 1.04 F. As a result, the cell of Example 6 had a slightly lower capacity retention than the cell of Example 5, but the filling factor was the same, and good results were obtained.

[0071] Example 7 A film-type capacitor cell was fabricated using the same method and conditions as the cell of Example 5, except that the number of positive electrodes was three, the number of negative electrodes was four, and the outer casing laminate film was folded twice on both sides, as shown in Figure 12B. The cell of Example 7 had a thinner outer casing thickness T of 2.00 mm compared to the cell of Example 5, but the area So of the upper surface of the outer casing and the area of ​​the effective portion 1a were the same, and the packing ratio was also the same at 30.9%. Therefore, the cell of Example 6 satisfied the requirements of claim 1 for the area So of the upper surface of the outer casing, the area Se of the effective portion 1a, and the thickness T of the outer casing.

[0072] The cell of Example 7 had a thickness T of 1.06 mm, which was thinner than the cells of Examples 5 and 6, but the area So of the upper surface of the exterior body was 135.68 mm ２ (=12.8 mm × 10.6 mm), the packing ratio was 29.7%, slightly lower than that of the cells of Examples 5 and 6. In addition, since 0.2978lnS0 - 1.2088 = 0.253, the cell of Example 7 also satisfies formula (I) of claim 1. Furthermore, the area S0 and thickness T of the upper surface of the exterior body also satisfy formulas (II) and (III) of claim 1, respectively, so the cell of Example 7 satisfies the requirements defined in claim 1.

[0073] The electrical characteristics of the cell of Example 7 were measured using the same method and conditions as in Example 5. The capacitance after 2000 hours was 0.44 F, and the capacity retention was 98.1%, compared to the initial capacitance of 0.45 F. As a result, the cell of Example 7 had an increased capacity retention compared to the cells of Examples 5 and 6, and good results were obtained.

[0074] Example 8 A cell of Example 8 was produced using the same method and conditions as the cell of Example 6, except that the thickness of the active material layer was increased to a thickness (total thickness) of 154 μm per positive electrode and negative electrode. The cell of Example 8 had a thicker exterior body thickness T of 2.93 mm than the cell of Example 6, but the area So of the upper surface of the exterior body and the area Se of the effective portion 1a were the same as those of the cell of Example 6, and the packing rate was also the same at 30.9%. Therefore, the cell of Example 8 also satisfied the requirements defined in claim 1 for the area So of the upper surface of the exterior body, the area Se of the effective portion 1a, and the thickness T of the exterior body.

[0075] Next, the electrical characteristics of the cell of Example 8 were measured using the same method and conditions as in Example 5. The capacitance after 2000 hours was 1.92 F, and the capacity retention was 97.9%, compared to the initial capacitance of 1.96 F. As a result, the cell of Example 8 had a slightly increased capacity retention compared to the cell of Example 6, and good results were obtained.

[0076] Example 9 As Example 9, a film-type lithium ion capacitor cell was produced by the method described below.

[0077] (1) Positive Electrode A positive electrode slurry was obtained by blending 87 parts by mass of CNT / graphene (carbon nanotube / graphene) powder with 5 parts by mass of acetylene black powder, 4 parts by mass of an acrylic binder, 4 parts by mass of carboxymethyl cellulose, and 210 parts by mass of water and thoroughly mixing the mixture.

[0078] The positive electrode slurry prepared by the above method was intermittently coated on both sides of a positive electrode current collector made of aluminum perforated foil with a thickness of 31 μm using a roll coater, which was then vacuum dried to form a positive electrode active material layer, thereby obtaining a positive electrode having a total thickness of 195 μm, which is the sum of the thickness of the positive electrode active material layers on both sides and the thickness of the current collector.

[0079] A 30 mm x 30 mm electrode piece was cut out from this positive electrode to serve as an electrode for evaluation. First, terminals were ultrasonically fused to each of the two evaluation electrodes, and the two electrodes were placed opposite each other with a 25 μm thick cellulose separator in between and housed in an exterior housing. An electrolyte solution was then poured into the exterior housing, and the exterior housing was heat-sealed with the ends of the electrode terminals pulled out from the exterior housing to obtain an evaluation cell. The exterior housing was made of a laminate film of polypropylene, aluminum, and nylon, and the electrolyte solution was a mixture of ethylene carbonate and diethyl carbonate in a volume ratio of 1:1, with LiPF added. ６ A solution in which the above was dissolved to a concentration of 1 mol / L was used.

[0080] The capacitance per unit mass of the evaluation cell fabricated by the above method was measured at room temperature over a potential range of 0 to 2.7 V. The capacitance per unit mass, C, was calculated using the following equation (5): where I is the constant current, m is the total mass of the two electrodes, and ΔV / Δt is the slope obtained by linearly fitting the discharge curve between the voltages Vmax and ½Vmax at the start of discharge. As a result, the capacitance per unit mass of the positive electrode for evaluation was 150 F / g.

[0081]

[0082] (2) Negative electrode: AT Electrode Co., Ltd., electrode material BELLFINE (registered trademark) LN-0001 powder (specific surface area < 30 m ２ 88 parts by mass of cellulose acylate copolymer (cellulose acetate / cellulose acetate stearate, particle diameter D50 = 1.5 ± 0.5 μm), 5 parts by mass of acetylene black powder, 3 parts by mass of an SBR (styrene butadiene rubber) binder, 4 parts by mass of carboxymethyl cellulose, and 210 parts by mass of water were blended and thoroughly mixed to obtain a negative electrode slurry.

[0083] The negative electrode slurry prepared by the above method was intermittently coated on both sides of a negative electrode current collector made of copper foil with a thickness of 21 μm using a roll coater, and the coated negative electrode current collector was vacuum dried to form a negative electrode active material layer, thereby obtaining a negative electrode having a total thickness of 66 μm, which is the sum of the thickness of the negative electrode active material layers on both sides and the thickness of the current collector.

[0084] A 30 mm x 30 mm electrode piece was cut out from this negative electrode to serve as an electrode for evaluation. A 30 mm x 30 mm x 100 μm thick lithium metal was used as a reference electrode as the counter electrode of this electrode for evaluation, and a 50 μm thick microporous polypropylene membrane was used as a separator. The two electrodes were placed facing each other and housed in an exterior case. An electrolyte solution was then poured into the exterior case, and the exterior case was heat-sealed with the end of the electrode terminal pulled out from the exterior case to obtain an evaluation cell. The electrolyte solution was a mixture of ethylene carbonate and diethyl carbonate in a volume ratio of 1:1, and LiPF ６ A solution in which the above was dissolved to a concentration of 1 mol / L was used.

[0085] The capacitance per unit mass of the evaluation cell fabricated by the above method was measured at room temperature in a potential range of 0 to 2.7 V. The measurement was performed by charging 500 mAh / g of lithium ions relative to the mass of the negative electrode active material at a charging current density of 50 mA / g, and then discharging to 3 V at 50 mA / g. As a result, the capacitance per unit mass of the negative electrode was calculated from the discharge time during which the potential changed by 0.2 V from the negative electrode potential 1 minute after the start of discharge, and was found to be 4000 F / g.

[0086] (3) Cell Preparation Eight positive electrodes each measuring 6.5 mm × 6.2 mm were cut out from the positive electrode, and nine negative electrodes each measuring 6.5 mm × 6.2 mm were cut out. These positive and negative electrodes were alternately stacked with separators interposed therebetween, dried at 120 ° C. for 12 hours, and then separators were stacked on the top and bottom of the stack and taped on the four sides. A lithium metal foil for pre-doping was pressed onto a copper lath and placed on the outermost side so as to face the positive electrode, thereby obtaining an electrode stack unit.

[0087] In this electrode laminate unit, an aluminum terminal (2 mm wide) was placed on the lead portion (2 mm wide) of the positive electrode current collector, and a nickel terminal (2 mm wide) was placed on the lead portion (2 mm wide) of the negative electrode current collector, and they were ultrasonically welded together. The weld size was 0.2 mm wide and 1.0 mm long.

[0088] Next, with the end of the terminal pulled out, the exterior laminate film was folded back, and both sides of the exterior laminate film were heat-sealed with a sealing width of 2 mm. After that, the exterior body was filled with an electrolyte solution of ethylene carbonate and diethyl carbonate mixed in a volume ratio of 1:1, and LiPF ６ A solution containing 1 mol / L of ethylenediaminetetraacetic acid (ETA) dissolved in ethylenediaminetetraacetic acid (ETA) at a concentration of 1 mol / L was injected into the electrode, and the electrode was vacuum-impregnated. The open top edge was then heat-sealed under reduced pressure with a sealing width of 2 mm to vacuum-seal the exterior. Then, as shown in FIG. 11A, both sides were folded back once to produce a lithium ion capacitor (LIC) cell with an exterior size of 12.8 mm long x 10.2 mm wide x 2.492 mm thick.

[0089] (4) Filling rate, etc. The filling rate of the cell of Example 9 produced by the above-described method is calculated as follows: Area of ​​the upper surface of the exterior body: So (Xo × Yo) = 12.8 mm × 10.2 mm = 130.56 mm ２ Area of ​​effective portion 1a: Se (Xe × Ye) = 6.5 mm × 6.2 mm = 40.3 mm ２Filling rate: Se / So×100=40.3 / 130.56×100=30.9% Here, 0.2978lnSo−1.2088=0.242, so the cell of Example 9 satisfies formula (I) of claim 1. In addition, the area So and thickness T of the upper surface of the exterior body also satisfy formulas (II) and (III) of claim 1, respectively, and the cell of Example 9 satisfies the requirements defined in claim 1.

[0090] (5) Electrical Characteristics of the Cell The cell of Example 9 was left for 14 days, and the cell voltage reached 2.7 V or higher, indicating that the lithium ions had been precharged. The cell was then charged at a constant current of 10 mA until the cell voltage reached 3.8 V, and then discharged at a constant current of 10 mA until the cell voltage reached 2.2 V. The initial capacitance was determined from this 3.8 V-2.2 V cycle. Next, for durability evaluation, the capacitance and capacitance retention after 2000 hours were determined by simulation. As a result, the initial capacitance was 4.47 F, while the capacitance after 2000 hours was 4.45 F, and the capacity retention was 99.6%, indicating favorable results.

[0091] Example 10 In Example 10, a film-type capacitor cell was produced using a positive electrode produced by changing the active material from a carbon nanotube / graphene composite (CNT / G) to activated carbon powder.

[0092] (1) Preparation of Positive and Negative Electrodes The method and conditions for preparing the positive and negative electrodes were as follows: ２ / g, particle size D ５０ The positive electrode was the same as in Example 9, except that the active material was changed to YP-50 activated carbon powder having a particle size of 5 μm. The total thickness of the positive electrode, which was the sum of the thicknesses of the active material layers on both sides and the current collector, was 201 μm. The capacitance per unit mass of the positive electrode was determined using the same method as in Example 9 and was found to be 100 F / g. The negative electrode of Example 10, including the active material, was the same as in Example 9, and therefore the capacitance per unit mass was also the same, 4000 F / g.

[0093] (2) Cell Fabrication Cells were fabricated using the same method and conditions as in Example 9. The cell of Example 10 had a slightly increased exterior body thickness T of 2.87 mm, but the area So of the upper surface of the exterior body and the area of ​​the effective portion 1a were the same as those of the cell of Example 1, and the packing rate was 30.9%, the same as that of the cell of Example 1. Therefore, the cell of Example 10 satisfied the requirements defined in claim 1 for all of the area So of the upper surface of the exterior body, the area Se of the effective portion 1a, and the thickness T of the exterior body.

[0094] (3) Electrical Characteristics of the Cell The electrical characteristics of the cell were measured in the same manner as in Example 9. The initial capacitance was 2.08 F, and the capacitance after 2000 hours was 2.06 F. The capacity retention rate was 99.3%, which was a good result.

[0095] Comparative Example 1 As Comparative Example 1, an electric double layer capacitor (EDLC) was fabricated using activated carbon as the active material in the same manner as in Examples 1 to 4. In Comparative Example 1, the electrode sizes of the positive and negative electrodes were changed to 5.2 mm × 6.2 mm, and the size of the welded portion was changed to a width of 1 mm and a length of 1 mm. Except for this, a cell was fabricated in the same manner and under the same conditions as in Example 1, and its electrical characteristics were measured.

[0096] The packing ratio of the cell in Comparative Example 1 is calculated as follows: Area of ​​the upper surface of the exterior body: So (Xo × Yo) = 12.8 mm × 10.2 mm = 130.56 mm ２ Area of ​​effective portion 1a: Se (Xe × Ye) = 5.2 mm × 6.2 mm = 32.2 mm ２ Filling rate: Se / So x 100 = 32.2 / 130.56 x 100 = 24.7% Here, 0.2978lnSo - 1.2088 = 0.242, so the cell of Comparative Example 1 satisfies formula (I) of claim 1. In addition, the area So and thickness T of the upper surface of the exterior body also satisfy formulas (II) and (III) of claim 1, respectively. However, the cell of Comparative Example 1 was outside the scope of the present invention because the width of the weld was 1 mm.

[0097] The electrical characteristics of the cell of Comparative Example 1 were measured in the same manner as in Example 9. The initial capacitance was 0.48 F, while the capacitance after 2000 hours was 0.46 F, and the capacity retention was 97.4%. Thus, the cell of Comparative Example 1 had a good capacity retention but a low filling factor.

[0098] Comparative Example 2 An electric double layer capacitor (EDLC) of Comparative Example 2 was produced in the same manner and under the same conditions as in Example 1, except that the sealing portions on the left and right sides of the exterior body were not folded.

[0099] In the cell of Comparative Example 2, the width Yo of the upper surface of the exterior body is increased by the amount of the sealing portion not folded, and the value of the area So of the upper surface of the exterior body is changed, so the filling rate is calculated as follows: Area of ​​the upper surface of the exterior body: So (Xo × Yo) = 12.8 mm × 13.8 mm = 176.64 mm ２ Area of ​​effective portion 1a: Se (Xe × Ye) = 6.5 mm × 6.2 mm = 40.3 mm ２ Filling rate: Se / So×100=40.3 / 176.64×100=22.8% Here, 0.2978lnSo−1.2088=0.332, so the cell of Comparative Example 2 did not satisfy formula (I) of claim 1.

[0100] The electrical characteristics of the cell of Comparative Example 2 were measured in the same manner as in Example 9. The initial capacitance was 0.57 F, while the capacitance after 2000 hours was 0.55 F, and the capacity retention was 96.8%. Thus, the cell of Comparative Example 2 had a good capacity retention but a low filling factor.

[0101] Comparative Example 3 An electric double layer capacitor (EDLC) of Comparative Example 4 was fabricated using the same method and conditions as in Example 1, except that the weld size was 0.1 mm in width and 1 mm in length. In the cell of Comparative Example 3, the width of the weld was narrower than the range of the present invention, and therefore the strength of the weld was insufficient, making it impossible to measure the electrical characteristics.

[0102] In Example 1, the resistance value in the thickness direction of the 0.1 mm thick aluminum foil used as the terminal was measured to be 13 mΩ, and when this was overlapped with the terminal weld (width 2 mm) of the current collector and ultrasonically welded with the size of the weld width 0.2 mm and length 1.0 mm, the resistance value in the thickness direction was 14 mΩ. From this difference, the resistance value in the thickness direction of the weld is estimated to be about 1 mΩ. On the other hand, in Comparative Example 3, the size of the weld was reduced to a width of 0.1 mm and a length of 1 mm, so the resistance value in the thickness direction exceeded 1 Ω, and it is thought that a welding defect occurred.

[0103] Reference Example An electric double layer capacitor (EDLC) of a reference example was produced in the same manner and under the same conditions as in Example 1, except that the sealing width of the left and right sides of the exterior body was set to 1 mm.

[0104] Narrowing the sealing width does not affect the area So of the upper surface of the exterior body, so the filling factor of the cell of Comparative Example 3 is the same as that of Example 1. Filling factor: Se / So x 100 = 40.3 / 176.64 x 100 = 30.9%. Here, 0.2978lnSo - 1.2088 = 0.242, so the cell of Comparative Example 3 satisfies formula (I) of claim 1. In addition, the area So of the upper surface of the exterior body and the thickness T also satisfy formulas (II) and (III) of claim 1, respectively.

[0105] The electrical characteristics of this cell of Reference Example were measured in the same manner as in Example 9. The capacitance after 2000 hours was 0.12 F, and the capacity retention was 31.2%, compared to the initial capacitance of 0.57 F. From these results, it was confirmed that the cell of Reference Example had a high filling factor but a low capacity retention, and that a sealing width of 1.0 mm was insufficient.

[0106] The results are shown in Tables 1 and 2 below.

[0107]

[0108]

[0109] From the above results, it was confirmed that the present invention can realize an organic electrolyte-based electricity storage device that is ultra-compact yet has a high energy density.

[0110] REFERENCE SIGNS LIST 1 Electrode 1a Active part 1b Lead part 2 Terminal 3 Exterior body 4 Welded part 5 Current collector 6 Positive electrode active material layer 7 Negative electrode active material layer 8 Separator 10 Electric storage device 11 Positive electrode 12 Negative electrode 20 Metal foil 21 Slurry 22 Active material layer 30 Coating and pressing device 31 Nozzle 32 Press roll 40 Ultrasonic welding device 41 Holding part 42 Anvil 43 Horn 44 Welded area

Claims

1. A device comprising: a plurality of electrodes stacked on top of one another; a plurality of terminals electrically connected to the plurality of electrodes; and an exterior body made of an aluminum laminate film; wherein the electrodes are provided with an effective portion that contributes to power storage and a lead portion to which the terminal is connected, the lead portion and the terminal are welded in the width direction of the terminal, the width of the weld portion being 0.15 to 0.8 mm; and wherein the area of ​​the upper surface of the exterior body is Somm in plan view. ２ , the area of ​​the effective part of the electrode is S e mm ２ When the thickness of the exterior body is T mm, the organic electrolyte solution-based electricity storage device satisfies the following formulas (I) to (III):

2. The organic electrolyte solution-based electricity storage device according to claim 1, wherein the plurality of electrodes comprise a positive electrode having a positive electrode active material applied to the effective portion and a negative electrode having a negative electrode active material applied to the effective portion, and the positive electrode active material and the negative electrode active material are active materials capable of absorbing and desorbing ions.

3. The organic electrolyte storage device according to claim 2, wherein the positive electrode active material and the negative electrode active material comprise a composite material of graphene and carbon nanotubes.

4. The organic electrolyte solution-based electricity storage device according to claim 1, wherein the plurality of electrodes comprise a positive electrode having a positive electrode active material applied to the effective portion and a negative electrode having a negative electrode active material applied to the effective portion, the positive electrode active material being an active material capable of absorbing and desorbing ions, and the negative electrode active material being an active material capable of absorbing and releasing lithium ions, and being pre-doped with lithium ions.

5. The organic electrolyte storage device according to claim 4, wherein the positive electrode active material comprises a composite material of graphene and carbon nanotubes.

6. A process for stacking a plurality of electrodes, each of which has an effective portion that contributes to power storage and a lead portion to which a terminal is connected, on one another; a process for connecting terminals to the plurality of electrodes; and a process for sealing the stacked electrodes to which the terminals are connected, with an exterior body made of an aluminum laminate film, wherein in the process for connecting the terminals to the plurality of electrodes, the terminals are welded in the width direction so that the width of the welded portion is 0.15 to 0.8 mm, and the area of ​​the upper surface of the exterior body in a plan view is Somm ２ , the area of ​​the effective part of the electrode is S e mm ２ A method for producing an organic electrolyte-based electricity storage device, which provides an electricity storage device that satisfies the following formulas (I) to (III), where T mm is the thickness of the exterior body:

7. A method for manufacturing an organic electrolyte storage device as described in claim 6, wherein the step of connecting terminals to the plurality of electrodes comprises ultrasonically welding the electrodes and the terminals using an ultrasonic welding device having a holding portion for holding the objects to be welded, an anvil, and a horn.

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