JP2010199281A - Electric storage device and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the safety of an electric storage device, and to improve the quality. <P>SOLUTION: An electrode stack unit 12 is provided with a separator 17 which is folded zigzag. A positive electrode 13 is stored in a positive storage part 26 of the separator 17, and negative electrodes 14, 15 are stored in a negative electrode storage part 27 of the separator 17. Further, both width-directional ends 17a of the separator 17 are closed in the stacking direction. Consequently, the positive electrode storage part 26 and negative storage part 27 have openings at different positions and the positive electrode 13 and negative electrodes 14, 15 are prevented from short-circuiting owing to a position shift or the like of the electrodes. Further, the negative electrode storage part 27 is formed in a bag shape, so even if metal lithium is dropped from the negative electrode 15 having a metal lithium foil, the metal lithium is prevented from separating. Consequently, an internal short circuit and corrosion of an exterior member caused by the free metal lithium can be prevented. Furthermore, the metal lithium having been dropped can be retained in the vicinity of the negative electrode 15 to achieve doping with lithium ions as designed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electricity storage device in which a negative electrode composite provided with an ion supply source is incorporated, and a method for manufacturing the same.

  Examples of power storage devices mounted on electric vehicles and hybrid vehicles include lithium ion capacitors and lithium ion secondary batteries. In order to improve the energy density of these electricity storage devices, an electricity storage device in which metallic lithium as an ion supply source is incorporated in the electricity storage device has been proposed. In this electricity storage device, metallic lithium is electrochemically connected to the negative electrode, and lithium ions are doped from the metallic lithium to the negative electrode. By performing charging / discharging between the positive and negative electrodes after this, it is possible to reduce the capacity loss of the electricity storage device when a negative electrode active material having a large amount of irreversible capacity is used for the negative electrode. Further, by doping lithium ions to the negative electrode, the negative electrode potential in the charged or discharged state of the electricity storage device can be reduced. That is, the average voltage of the electricity storage device can be increased by lowering the average potential of the negative electrode. As a result, the energy density of the electricity storage device can be improved. Further, as a method of incorporating metallic lithium into the electricity storage device, a method of attaching metallic lithium foil to the negative electrode current collector has been proposed (see, for example, Patent Document 1). Further, a method of directly attaching a metal lithium foil on the negative electrode mixture (for example, see Patent Document 2) and a method of forming a metal lithium layer by vapor deposition and transferring the metal lithium layer onto the negative electrode mixture layer are proposed. (For example, see Patent Document 3).

JP 2008-123826 A JP-A-11-283676 JP 2008-21901 A

  However, simply incorporating metal lithium into the electricity storage device may cause metal lithium pieces or metal lithium particles to be released into the electricity storage device when a portion of the metal lithium falls off the metal lithium foil or metal lithium layer. There is. As described above, the release of the metal lithium pieces and metal lithium fine particles from the original arrangement location in the electricity storage device causes an internal short circuit of the electricity storage device, corrosion of the exterior material, and the like, thereby reducing the safety of the electricity storage device. It was. Further, when an abnormal situation occurs in which the power storage device opens due to an internal short circuit or overcharge, the dropped metal lithium pieces and metal lithium fine particles are scattered in the atmosphere. Furthermore, a part of the metallic lithium falling off and liberated from the negative electrode has been a factor of lowering the lithium ion doping amount and lowering the quality of the electricity storage device.

  An object of the present invention is to improve the safety and quality of an electricity storage device.

  An electricity storage device of the present invention is an electricity storage device in which a positive electrode including a positive electrode current collector and a positive electrode composite material layer and a negative electrode including a negative electrode current collector and a negative electrode composite material layer are alternately stacked and folded in a zigzag shape. And a strip-shaped separator that alternately forms a positive electrode accommodating portion that accommodates the positive electrode and a negative electrode accommodating portion that accommodates the negative electrode, wherein at least one of the negative electrodes includes the negative electrode current collector and the negative electrode mixture layer In addition, the separator is configured as a negative electrode composite having an ion supply source, and both end portions in the width direction of the separator are closed in the stacking direction under a zigzag folded state.

  The electricity storage device of the present invention is characterized in that the folded portion of the separator provided on the opening side of the negative electrode housing portion is closed in the stacking direction.

  The electricity storage device of the present invention is characterized in that the folded portion of the separator provided on the opening side of the negative electrode housing portion is covered with an extension provided at an end portion in the longitudinal direction of the separator.

  The electricity storage device of the present invention is characterized in that an outer edge of the ion supply source is disposed on an inner side than an outer edge of the negative electrode current collector.

  The electricity storage device of the present invention is characterized in that a plurality of through holes are formed in the positive electrode current collector and the negative electrode current collector.

  The method for producing an electricity storage device of the present invention is a method for producing an electricity storage device in which a positive electrode including a positive electrode current collector and a positive electrode mixture layer and a negative electrode including a negative electrode current collector and a negative electrode mixture layer are alternately stacked. A step of folding the strip-shaped separator into a zigzag shape, and alternately forming a positive electrode accommodating portion that accommodates the positive electrode and a negative electrode accommodating portion that accommodates the negative electrode, and at least one of the negative electrode, the negative electrode current collector and A step of forming a negative electrode composite material including an ion supply source in addition to the negative electrode mixture layer, and a step of closing both end portions of the separator in the width direction in a zigzag folded state. It is characterized by having.

  In the present invention, the strip-shaped separator is folded back in a zigzag shape, and both end portions in the width direction of the separator are closed. Therefore, the negative electrode housing portion can be formed in a bag shape. As a result, the openings of the positive electrode housing portion and the negative electrode housing portion are located at different positions, so that even when the electrode is misaligned, a short circuit between the positive electrode and the negative electrode can be avoided, improving the safety of the electricity storage device. It becomes possible to make it. Further, even when the ion supply source is dropped from the negative electrode composite material, it is possible to prevent the ion supply source from moving from the negative electrode housing portion to the positive electrode housing portion, which causes the liberation of the ion supply source. Short circuit in the electricity storage device and corrosion of the exterior material can be prevented, and the safety of the electricity storage device can be improved. Furthermore, since the negative electrode accommodating portion is formed in a bag shape, it is possible to hold the ion supply source in the vicinity of the negative electrode (negative electrode composite material) even when the ion supply source is dropped from the negative electrode composite material. . As a result, the ion doping amount can be ensured as designed, and the performance degradation of the electricity storage device can be prevented. In addition, since the ion supply source is provided on the negative electrode, the current collector for the ion supply source can be reduced. Thereby, it becomes possible to improve the energy density of an electrical storage device.

It is a perspective view which shows the electrical storage device which is one embodiment of this invention. It is sectional drawing which shows schematically the internal structure of an electrical storage device along the AA line of FIG. It is sectional drawing which expands and shows the internal structure of an electrical storage device partially. It is a disassembled perspective view which shows the assembly structure of an electrode lamination | stacking unit. It is explanatory drawing which shows the sealing position of the separator which comprises an electrode lamination unit. FIG. 6 is a cross-sectional view schematically showing an internal structure of the electrode stacking unit along an instruction line A in FIG. 5. It is a disassembled perspective view which shows the structure of a negative electrode. It is a disassembled perspective view which shows the assembly structure of the electrode lamination | stacking unit with which the electrical storage device which is other embodiment of this invention is provided. It is explanatory drawing which shows the sealing position of the separator which comprises an electrode lamination unit. It is sectional drawing which shows the internal structure of the electrode lamination | stacking unit provided in the electrical storage device which is other embodiment of this invention. It is sectional drawing which shows the internal structure of the electrode lamination | stacking unit provided in the electrical storage device which is other embodiment of this invention. It is sectional drawing which shows the internal structure of the electrode lamination | stacking unit provided in the electrical storage device which is other embodiment of this invention. It is sectional drawing which shows partially the internal structure of the electrical storage device which is other embodiment of this invention.

  FIG. 1 is a perspective view showing an electricity storage device 10 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing the internal structure of the electricity storage device 10 along the line AA in FIG. As shown in FIGS. 1 and 2, an electrode stacking unit 12 is accommodated in an exterior material 11 configured using a laminate film. The electrode stacking unit 12 includes positive electrodes 13 and negative electrodes 14 and 15 that are alternately stacked. Furthermore, the negative electrode 15 disposed on the outermost part of the electrode laminate unit 12 is configured as a negative electrode composite material integrally provided with a metal lithium foil 16 as an ion supply source. In addition, a strip-shaped separator 17 that is folded back in a zigzag manner is provided in the electricity storage device 10. The separator 17 is folded back so as to sew between the positive electrode 13 and the negative electrodes 14 and 15. Note that an electrolyte is injected into the exterior material 11. This electrolytic solution is composed of an aprotic polar solvent containing a lithium salt.

  FIG. 3 is a cross-sectional view showing a partially enlarged internal structure of the electricity storage device 10. As shown in FIG. 3, the positive electrode 13 has a positive electrode current collector 20 having a large number of through holes 20a. The positive electrode current collector 20 is provided with a positive electrode mixture layer 21. The positive electrode current collector 20 is provided with a terminal joint portion 20b extending in a convex shape. The plurality of terminal joint portions 20b are joined to each other in a stacked state. Further, the positive terminal 22 is joined to the terminal joint portion 20b.

  Similarly, the negative electrodes 14 and 15 have a negative electrode current collector 23 having a large number of through holes 23a. A negative electrode mixture layer 24 is provided on both surfaces of the negative electrode current collector 23 constituting the negative electrode 14. A negative electrode mixture layer 24 is provided on one surface of the negative electrode current collector 23 constituting the negative electrode 15, and a metal lithium foil 16 as an ion supply source is provided on the other surface of the negative electrode current collector 23 constituting the negative electrode 15. Is pasted. Further, the negative electrode current collector 23 is provided with a terminal joint portion 23b extending in a convex shape. The plurality of terminal joining portions 23b are joined to each other in an overlapped state. Further, the negative electrode terminal 25 is bonded to the terminal bonding portion 23b.

  The positive electrode mixture layer 21 contains activated carbon as a positive electrode active material. This activated carbon can be reversibly doped and dedoped with lithium ions and anions. Further, the negative electrode mixture layer 24 includes polyacene organic semiconductor (PAS) as a negative electrode active material. This PAS can be reversibly doped / undoped with lithium ions. In this manner, by using activated carbon as the positive electrode active material and PAS as the negative electrode active material, the power storage device 10 illustrated functions as a lithium ion capacitor.

  The power storage device 10 to which the present invention is applied is not limited to a lithium ion capacitor, and may be a lithium ion secondary battery or an electric double layer capacitor, such as a magnesium ion secondary battery. It may be a type of battery or a hybrid capacitor with these. Further, in this specification, doping (doping) means occlusion, support, adsorption, insertion, and the like. That is, dope means a state in which anions, lithium ions, and the like enter the positive electrode active material and the negative electrode active material. De-doping (de-doping) means release, desorption and the like. That is, dedoping means a state in which anions, lithium ions, and the like are emitted from the positive electrode active material and the negative electrode active material.

  As described above, the metal lithium foil 16 is attached to the negative electrode current collector 23 of the negative electrode 15. The negative electrode current collectors 23 of the negative electrodes 14 and 15 are joined to each other. That is, the metal lithium foil 16 and all the negative electrode mixture layers 24 are electrically connected. Therefore, by injecting the electrolytic solution into the exterior material 11, lithium ions are doped (hereinafter referred to as pre-doping) from the metal lithium foil 16 to the negative electrodes 14 and 15. Further, through holes 20 a and 23 a are formed in the positive electrode current collector 20 and the negative electrode current collector 23. For this reason, the lithium ions released from the metal lithium foil 16 pass through the through holes 20a and 23a of the current collectors 20 and 23 and move in the stacking direction. This makes it possible to smoothly pre-dope lithium ions for all the negative electrodes 14 and 15 to be stacked.

Thus, the negative electrode potential can be lowered by pre-doping lithium ions into the negative electrodes 14 and 15. Thereby, the cell voltage of the electricity storage device 10 can be increased. Moreover, it becomes possible to increase the electrostatic capacity of the negative electrodes 14 and 15 by pre-doping lithium ions into the negative electrodes 14 and 15. Thereby, the electrostatic capacity of the electricity storage device 10 can be increased. Furthermore, by increasing the capacitance of the negative electrodes 14 and 15, the potential range (potential difference) in which the positive electrode 13 operates can be expanded, and the cell capacity (discharge capacity) of the electricity storage device 10 can be increased. Thus, since the cell voltage, cell capacity, and electrostatic capacity of the electricity storage device 10 can be increased, the energy density of the electricity storage device 10 can be improved. Further, from the viewpoint of increasing the capacity of the electricity storage device 10, the metal lithium is adjusted so that the positive electrode potential after the positive electrode 13 and the negative electrodes 14 and 15 are short-circuited is 2.0 V (vs. Li ^/ Li ⁺ ) or less. It is preferable to set the amount of the foil 16.

  As shown in FIGS. 2 and 3, the configuration in which the negative electrode 15 as the negative electrode composite material is disposed at the outermost part of the electrode laminated unit 12 has been described. However, the negative electrode composite material is disposed between the positive electrodes 13 positioned in the inner layer of the electrode laminated unit 12. You may arrange | position so that it may pinch | interpose. Further, the negative electrode composite material may be arranged on the outermost part of the electrode laminated unit 12 and the negative electrode composite material may be arranged between the positive electrodes 13 located in the inner layer of the electrode laminated unit 12. Thus, the lithium ion doping rate can be increased by finely disposing the negative electrode composite material in the electrode stack unit 12 (power storage device 10). Moreover, about the negative electrode composite material for arrange | positioning in the inner layer of the electrode lamination | stacking unit 12, it is from a viewpoint of productivity that it adheres and comprises the metal lithium foil 16 on the negative electrode 14 provided with the negative electrode compound material layer 24 on both surfaces. preferable. However, disposing the negative electrode composite material in the inner layer of the electrode laminate unit 12 is disadvantageous in terms of work efficiency in the first place. Therefore, in consideration of work efficiency, the negative electrode composite material is disposed on the outermost part of the electrode laminate unit 12. It is preferable to arrange them. Therefore, in order to improve the working efficiency and increase the doping rate of lithium ions, a plurality of electrode laminate units having a negative electrode composite material arranged on the outermost part are produced, and then the plurality of electrode laminate units are laminated to store electricity. It is desirable to configure the device.

  Furthermore, as shown in FIG. 3, the negative electrode (negative electrode composite material) 15 disposed on the outermost part of the electrode laminate unit 12 is configured by attaching a metal lithium foil 16 to the uncoated surface of the negative electrode current collector 23. ing. However, the negative electrode composite material to be disposed on the outermost part of the electrode laminate unit 12 may be configured by attaching the metal lithium foil 16 to the negative electrode 14 provided with the negative electrode mixture layer 24 on both surfaces. Thus, when the negative electrode composite material composed of the negative electrode 14 and the metal lithium foil 16 is disposed on the outermost part of the electrode laminate unit 12, it is preferable to dispose the surface on which the metal lithium foil 16 is provided facing outward. . This is because by arranging the metal lithium foil 16 facing outward, the metal lithium foil 16 can be easily brought into contact with the electrolytic solution and ionization can be easily achieved.

  However, disposing the negative electrode composite material provided with the two negative electrode mixture layers 24 at the outermost part of the electrode laminate unit 12 contributes to the negative electrode mixture layer 24 that does not face the positive electrode mixture layer 21, that is, charge / discharge. The difficult negative electrode mixture layer 24 is incorporated into the electricity storage device 10. This not only leads to an increase in the amount of electrolyte and cell weight and a decrease in energy density due to an increase in the volume of the electricity storage device, but also may disrupt the charge / discharge balance between the positive and negative electrodes in the electricity storage device 10. There is a risk of adversely affecting properties.

  On the other hand, as shown in FIG. 3, in order to dispose the negative electrode 15 having the negative electrode mixture layer 24 on one side as the negative electrode composite material on the outermost part of the electrode laminate unit 12, the negative electrode mixture layer 24 is provided on both surfaces. In addition to manufacturing the negative electrode 14, it is necessary to manufacture the negative electrode 15 including the negative electrode mixture layer 24 on one side. That is, since it is necessary to manufacture two types of negative electrodes 14 and 15, it is not preferable in view of productivity. Also, in the laminating process of the electrode laminating unit 12, since the two types of negative electrodes 14 and 15 are used, the laminating operation becomes complicated, which is not preferable in view of productivity. From the above, the negative electrode composite material composed of the negative electrode 15 having the negative electrode mixture layer 24 on one side is disposed on the outermost part of the electrode laminate unit 12, or the negative electrode 14 having the negative electrode mixture layer 24 on both sides is provided. Whether to dispose the negative electrode composite material is preferably selected in consideration of the performance and productivity of the electricity storage device 10.

  In addition, although the structural example which arrange | positions the negative electrode 14 provided with the negative mix layer 24 on both surfaces in the outermost part of the electrode lamination | stacking unit 12 was described, it was not restricted to this, The positive mix layer 21 was provided on both surfaces The positive electrode 13 may be disposed on the outermost part of the electrode laminated unit 12. Thus, in the case where the electrode (positive electrode or negative electrode) provided with the electrode mixture layer (positive electrode mixture layer or negative electrode mixture layer) on both sides is arranged on the outermost part of the electrode laminate unit 12, It is preferable to arrange an electrode having a large capacity at the outermost part. That is, the capacity of the electricity storage device 10 is governed by the electrode having a small capacity of the positive electrode or the negative electrode, but by arranging this electrode in the inner layer of the electrode laminated unit 12, the small capacity of the electrode is left. The energy density of the electricity storage device 10 can be improved.

  Then, the structure of the electrode lamination | stacking unit 12 with which the electrical storage device 10 of this invention is provided is demonstrated. FIG. 4 is an exploded perspective view showing the assembly structure of the electrode stacking unit 12. As shown in FIG. 4, the strip-shaped separator 17 constituting the electrode laminated unit 12 is folded back at intervals corresponding to the length dimensions of the positive electrode 13 and the negative electrodes 14 and 15. Thus, the separator 17 folded back in a zigzag shape is formed with a positive electrode housing portion 26 opened on one side and a negative electrode housing portion 27 opened on the other side. Moreover, the positive electrode accommodating part 26 and the negative electrode accommodating part 27 are formed so that it may overlap with each other. Each positive electrode accommodating portion 26 accommodates one positive electrode 13 and each negative electrode accommodating portion 27 accommodates negative electrodes 14 and 15 one by one. By configuring the electrode laminate unit 12 in this way, the separator 17 is sandwiched between the positive electrode 13 and the negative electrodes 14 and 15 facing each other. Further, by using one separator 17 folded in a zigzag shape, the electrode stacking unit 12 can be easily assembled, and the power storage device 10 can be easily assembled.

  FIG. 5 is an explanatory view showing a sealing position of the separator 17 constituting the electrode stacking unit 12. FIG. 6 is a cross-sectional view schematically showing the internal structure of the electrode stacking unit 12 along the instruction line A of FIG. As shown by a one-dot chain line α in FIG. 5, both end portions 17a in the width direction of the separator 17 folded back in a zigzag shape are closed in the stacking direction. And as shown in FIG. 6, the positive electrode accommodating part 26 and the negative electrode accommodating part 27 will be in the state partitioned by the bag shape by closing the both ends 17a of the separator 17 in the width direction. Examples of means for closing both end portions 17a of the separator 17 include tape fastening with an adhesive tape, adhesion with a polymer adhesive, and the like. By using these means, both end portions 17a of the separator 17 can be closed. When the material of the separator 17 includes a thermoplastic resin such as polyethylene or polypropylene, both end portions 17a of the separator 17 can be closed by a heat fusion process in addition to the above means. Furthermore, the both ends 17a of the separator 17 may be closed by combining tape fastening with an adhesive tape, adhesion with a polymer adhesive, and heat fusion treatment.

  In this way, by closing both end portions 17a in the width direction of the separator 17 folded back in a zigzag shape, as shown in FIG. 3, the opening portion 26a of the positive electrode housing portion 26 and the opening portion 27a of the negative electrode housing portion 27 are formed. Each can be arranged on the opposite side. Thereby, even when the positional deviation of the electrode occurs, a short circuit between the positive electrode 13 and the negative electrodes 14 and 15 can be avoided, and the safety of the electricity storage device 10 can be improved. Further, not only the negative electrode housing portion 27 is formed in a bag shape, but also as shown by an arrow A in FIG. 3, the negative electrode housing portion 27 and the positive electrode housing portion 26 are connected by a long detour path. For this reason, even if metallic lithium falls off from the negative electrode 15, it becomes possible to prevent the movement of this metallic lithium to the positive electrode 13. Thereby, it is possible to prevent internal short circuit and corrosion of the exterior material 11 due to metallic lithium liberated inside the electricity storage device 10, and the safety of the electricity storage device 10 can be improved. In addition, even when metallic lithium is dropped from the negative electrode 15, the metallic lithium can be held in the vicinity of the negative electrode 15, so that the doping amount of lithium ions can be ensured as designed. Thereby, it becomes possible to prevent the capacity | capacitance fall and output fall of the electrical storage device 10. FIG. Furthermore, since the negative electrode 15 in which the metal lithium foil 16 is integrated is provided, it is possible to reduce the lithium electrode current collector for holding the metal lithium foil 16. Thereby, since the weight and volume of the electrical storage device 10 can be reduced, the energy density of the electrical storage device 10 can be improved.

  In the above description, both end portions 17a in the width direction of the separator 17 are closed. However, in addition to the both end portions 17a, the folded portion 17b located on the opening side of the negative electrode housing portion 27 may be closed. As indicated by a two-dot chain line β in FIG. 5, the negative electrode accommodating portions 27 can be sealed by closing the folded portion 17 b on the opening side of the negative electrode accommodating portion 27 in the stacking direction. Thereby, even if metallic lithium is dropped from the negative electrode 15, it is possible to reliably prevent the metallic lithium from flowing out of the negative electrode housing portion 27. Therefore, the safety of the electricity storage device 10 can be further improved, and the exterior material 11 can be prevented from being corroded and the capacity and output of the electricity storage device 10 can be reduced. Furthermore, since it is possible to keep the metallic lithium in the sealed negative electrode housing portion 27, it is possible to prevent the metallic lithium from being scattered into the atmosphere when the electricity storage device 10 is opened, The safety of the electricity storage device 10 at the time can also be improved.

  The negative electrode current collector 23 is provided with a terminal joint portion 23b extending in a convex shape. As means for closing the folded-back portion 17b of the separator 17 that overlaps with the terminal joint portion 23b, it is preferable to use heat fusion treatment or adhesion with a polymer adhesive. By subjecting the folded portion 17 b to heat fusion treatment or adhesion treatment using a polymer adhesive, it is possible to insulate the surface of the terminal joint portion 23 b close to the negative electrode mixture layer 24. Thereby, precipitation of metallic lithium to the terminal joint part 23b accompanying a charging / discharging cycle can be suppressed.

  FIG. 7 is an exploded perspective view showing the structure of the negative electrode 15. As shown in FIG. 7, the metal lithium foil 16 is attached to the negative electrode current collector 23, but the metal lithium foil 16 is attached so that the outer edge of the metal lithium foil 16 is located inside the outer edge of the negative electrode current collector 23. Yes. As described above, the safety of the electricity storage device 10 can be improved by attaching the metal lithium foil 16 to the inside. That is, when the both ends 17a and the folded portion 17b of the separator 17 are closed by the heat fusion treatment, the vicinity of the end of the negative electrode 15 is heated. However, the metallic lithium foil 16 can be separated from the heated portion. It becomes possible. Thereby, the safety of the electricity storage device 10 can be further improved. Further, when the metal lithium foil 16 protrudes from the negative electrode 15, the metal lithium foil 16 may remain after pre-doping, but the remaining state of the metal lithium foil 16 can be avoided. Depending on the dimensions of the negative electrode 15 and the sealing position of the separator 17, it is preferable to set a clearance C of 1 mm or more between the outer edge of the metal lithium foil 16 and the outer edge of the negative electrode current collector 23.

  Furthermore, in the case shown in FIG. 4, the separator 17 is folded back at intervals corresponding to the length dimension of the positive electrode 13 and the negative electrodes 14, 15, but the separator 17 depends on the width dimension of the positive electrode 13 and the negative electrodes 14, 15. It may be folded back at intervals. Here, FIG. 8 is an exploded perspective view showing an assembly structure of the electrode laminated unit 30 provided in the electricity storage device according to another embodiment of the present invention. In FIG. 8, the same members as those shown in FIG. 4 are denoted by the same reference numerals, and the description thereof is omitted. FIG. 9 is an explanatory view showing a sealing position of the separator 31 constituting the electrode stacking unit 30.

  As shown in FIG. 8, the strip-shaped separator 31 constituting the electrode laminated unit 30 is folded back at intervals according to the width dimensions of the positive electrode 13 and the negative electrodes 14 and 15. Thus, the separator 31 folded back in a zigzag manner is formed with a positive electrode housing part 32 that opens on one side and a negative electrode housing part 33 that opens on the other side. Each positive electrode accommodating portion 32 accommodates one positive electrode 13 and each negative electrode accommodating portion 33 accommodates negative electrodes 14 and 15 one by one. Then, as shown by a one-dot chain line α in FIG. 9, both end portions 31a in the width direction of the separator 31 folded back in a zigzag shape are closed in the stacking direction. Thus, even when the separator 31 is folded back at intervals corresponding to the width dimensions of the positive electrode 13 and the negative electrodes 14 and 15, it is possible to obtain the same effects as those of the electricity storage device 10 described above. Note that, as indicated by a two-dot chain line β in FIG. 9, it goes without saying that each negative electrode accommodating portion 33 may be sealed by closing the folded portion 31 b on the opening side of the negative electrode accommodating portion 33.

  Further, as indicated by a two-dot chain line β in FIG. 9, not only the folded portion 31b of the separator 31 is closed, but the folded portion may be covered using an extended portion of the separator cut out longer. Here, FIG. 10 to FIG. 12 are cross-sectional views showing the internal structure of the electrode laminated units 41, 44, 47 provided in the electric storage device according to another embodiment of the present invention. 10A to 12A show a state before covering the folded portions 40c, 43d, and 46d, and FIGS. 10B to 12B show the folded portions 40c, 43d, and 46d. The state after covering is shown. 10 to 12 is a cross-sectional portion similar to the cross-sectional portion along the instruction line A in FIG. 9. 10 to 12, the same members as those illustrated in FIG. 8 are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 10 (A), the strip-shaped separator 40 folded back in a zigzag shape is formed longer than the separator 31 described above. As a result, when the electrode stack unit 41 is formed by folding the separator 40 in a zigzag shape, an extension 40 a is formed at one end in the longitudinal direction of the separator 40. Then, as shown in FIGS. 10A and 10B, the extension 40a provided at one end of the separator 40 covers the folded portion 40c provided on the opening side of the negative electrode housing 40b. After being wound around the outer periphery of the unit 41, it is stopped by the adhesive tape 42 or the like. In this manner, by covering the folded portion 40c with the extension 40a of the separator 40, it is possible to close each negative electrode housing portion 40b. Thereby, it is possible to obtain the same effect as the power storage device 10 described above.

  Further, as shown in FIG. 11A, the strip-shaped separator 43 folded back in a zigzag shape is formed longer than the separator 31 described above. Thus, when the electrode stacking unit 44 is formed by folding the separator 43 in a zigzag shape, a first extension 43a is formed at one end in the longitudinal direction of the separator 43, and at the other end in the longitudinal direction of the separator 43. The second extension 43b is formed. Then, as shown in FIGS. 11A and 11B, the folded portions 43d provided on the opening side of the negative electrode accommodating portion 43c are covered with the extension portions 43a and 43b provided in the separator 43, and then overlapped with each other. The extended portions 43a and 43b are stopped by an adhesive tape 45 or the like. In this manner, by covering the folded portion 43d with the extension portions 43a and 43b of the separator 43, it is possible to close the respective negative electrode accommodating portions 43c. Thereby, it is possible to obtain the same effect as the power storage device 10 described above.

  Further, as shown in FIG. 12A, the strip-shaped separator 46 folded back in a zigzag shape is formed longer than the separator 31 described above. Thus, when the electrode stacking unit 47 is formed by folding the separator 46 in a zigzag shape, the first extension 46 a is formed at one end in the longitudinal direction of the separator 46, and the other end in the longitudinal direction of the separator 46 is formed. The second extension 46b is formed. Then, as shown in FIGS. 12A and 12B, the extension 46a provided at one end of the separator 46 covers the folded portion 46d provided on the opening side of the negative electrode housing 46c. After being wound around the outer periphery of the unit 47, it is stopped by an adhesive tape 48 or the like. The extension 46b provided at the other end of the separator 46 is wound around the outer periphery of the electrode stack unit 47 by an adhesive tape 49 so as to cover the folded portion 46f provided on the opening side of the positive electrode housing 46e. It can be stopped. In this manner, by covering the folded portion 46d with the extension 46a of the separator 46, it is possible to close each negative electrode housing portion 46c. Thereby, it is possible to obtain the same effect as the power storage device 10 described above. In addition to closing the negative electrode housing portion 46c, the positive electrode housing portion 46e is also closed by the extension 46b at the other end, so that further safety of the electric storage device can be ensured.

  Incidentally, as shown in FIGS. 3 and 6, the positive electrode current collector 20 and the negative electrode current collector 23 are formed with a plurality of through holes 20a and 23a, but the present invention is not limited to this. You may make it use the negative electrode collector which does not have 20a, 23a, and a positive electrode collector. Here, FIG. 13 is a cross-sectional view partially showing the internal structure of an electricity storage device 50 according to another embodiment of the present invention. In addition, about the member same as the member shown in FIG. 3, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As illustrated in FIG. 13, the electrode stacking unit 51 of the electricity storage device 50 includes positive electrodes 52 and negative electrodes 53 that are alternately stacked. The positive electrode 52 has a flat positive electrode current collector 54. The positive electrode current collector 54 is provided with the positive electrode mixture layer 21. The negative electrode 53 as the negative electrode composite material has a flat negative electrode current collector 55. The negative electrode current collector 55 is provided with the negative electrode mixture layer 24. Further, a metal lithium foil 56 as an ion supply source is attached on the negative electrode mixture layer 24 of the negative electrode 53. A separator 17 folded back in a zigzag shape is provided so as to be sandwiched between the positive electrode 52 and the negative electrode 53 facing each other. In the outermost negative electrode 53, the negative electrode mixture layer 24 and the metal lithium foil 56 are provided only on one side (inner side) of the negative electrode current collector 55.

  As described above, when the metal lithium foil 56 is attached to all the negative electrode mixture layers 24, the positive electrode current collector 54 and the negative electrode current collector are used when doping all the negative electrode mixture layers 24 with lithium ions. There is no need to move lithium ions in the stacking direction beyond 55. Thereby, a through-hole can be reduced from the positive electrode current collector 54 or the negative electrode current collector 55, the manufacturing cost of the positive electrode current collector 54 and the negative electrode current collector 55, the positive electrode mixture layer 21, and the negative electrode mixture layer. Thus, the coating cost of 24 can be reduced. Even in the case of using such a negative electrode 53, the separator 17 folded in a zigzag shape is used, and the both ends 17a in the width direction of the separator 17 are closed, so that the metallic lithium is similar to the above-described power storage device 10. Can be prevented. Thereby, the short circuit and the corrosion of the exterior material 11 caused by the liberated metallic lithium can be prevented, and the safety of the electricity storage device 50 can be improved. Furthermore, since the openings of the positive electrode housing portion 26 and the negative electrode housing portion 27 are located at different positions, it is possible to avoid a short circuit between the positive electrode 42 and the negative electrode 43 due to an electrode misalignment or the like. Can be increased. Further, the doping amount of lithium ions can be ensured as designed, and the quality of the electricity storage device 50 can be improved.

  As shown in FIG. 3, the metal lithium foil 16 is directly attached to the negative electrode current collector 23. However, the present invention is not limited to this, and the negative electrode current collector 23 and the metal lithium foil 16 are not limited thereto. Between these, an auxiliary layer as described in JP-A-2001-15172 may be provided. By attaching the metal lithium foil 16 to the negative electrode current collector 23 via an auxiliary layer, it is possible to suppress an increase in electrode resistance accompanying the attachment of the metal lithium foil 16. As shown in FIG. 13, the metal lithium foil 56 is directly attached to the negative electrode mixture layer 24. However, the present invention is not limited to this, and the negative electrode mixture layer 24 and the metal lithium foil 56 are not limited thereto. Between these, an auxiliary layer as described in JP-A-2001-15172 may be provided. By attaching the metal lithium foil 56 to the negative electrode mixture layer 24 via the auxiliary layer, it is possible to suppress an increase in electrode resistance accompanying the attachment of the metal lithium foil 56.

  Hereinafter, the components of the electricity storage device described above will be described in detail in the following order. [A] positive electrode, [B] negative electrode, [C] positive electrode current collector and negative electrode current collector, [D] ion supply source, [E] separator, [F] electrolyte solution, [G] exterior material.

[A] Positive Electrode The positive electrode has a positive electrode current collector and a positive electrode mixture layer integrated therewith. When the electric storage device functions as a lithium ion capacitor, it is possible to employ a material capable of reversibly doping and dedoping lithium ions and / or anions as the positive electrode active material contained in the positive electrode mixture layer. . That is, there is no particular limitation as long as it is a substance capable of reversibly doping and dedoping at least one of lithium ions and anions. For example, activated carbon, a metal oxide such as RuO ₂ , a conductive polymer, a polyacene-based material, or the like can be used.

For example, the activated carbon is preferably formed from activated carbon particles having an alkali activation treatment and a specific surface area of 600 m ² / g or more. As a raw material for the activated carbon, phenol resin, petroleum pitch, petroleum coke, coconut shell, coal-based coke and the like are used. Phenol resin and coal-based coke are preferable because the specific surface area can be increased. The alkali activator used for the alkali activation treatment of these activated carbons is preferably an alkali metal hydroxide salt such as lithium, sodium or potassium. Of these, potassium hydroxide and sodium hydroxide are preferred. Examples of the alkali activation method include a method in which a carbide and an activator are mixed and then heated in an inert gas stream. Further, there is a method in which an activation agent is supported on the raw material of activated carbon in advance and then heated to perform carbonization and activation processes. Furthermore, after activating carbide by a gas activation method such as water vapor, a method of surface treatment with an alkali activating agent is also included. The activated carbon that has been subjected to such alkali activation treatment is subjected to removal of residual ash and pH adjustment by washing, and then pulverized using a known pulverizer such as a ball mill. As the particle size of the activated carbon, a wide range of commonly used materials can be used. For example, D50% is 2 μm or more, preferably 2 to 50 μm, and most preferably 2 to 20 μm. The average pore diameter is preferably 1.5 nm or more. The specific surface area is preferably 600 to 3000 m ² / g. Among them, 1500 m ² / g or more, and particularly it is preferable that a 1800~2600m ² / g.

In addition, when the power storage device functions as a lithium ion secondary battery, the positive electrode active material contained in the positive electrode mixture layer can be reversibly doped / dedoped with a conductive polymer such as polyaniline or lithium ions. It is possible to adopt a substance. For example, vanadium pentoxide (V ₂ O ₅ ) or lithium cobaltate (LiCoO ₂ ) can be used as the positive electrode active material. In addition, Li _X M _Y O _Z such as Li _X CoO ₂ , Li _X NiO ₂ , Li _X MnO ₂ , and Li _X FeO ₂ (x, y, z are positive numbers, M is a metal, two or more types It is also possible to use lithium-containing metal oxides that can be represented by the general formula (1), transition metal oxides such as cobalt, manganese, vanadium, titanium, nickel, or sulfides. In particular, when a high voltage is required, it is preferable to use a lithium-containing metal oxide having a potential of 4 V or more with respect to metal lithium. For example, lithium-containing cobalt oxide, lithium-containing nickel oxide, or lithium-containing cobalt-nickel composite oxide is particularly suitable. When safety is required, it is preferable to use a material that does not easily release oxygen from the structure even in a high temperature environment. For example, lithium iron phosphate, lithium iron silicate, vanadium oxide, and the like can be given. In addition, the positive electrode active material illustrated above may be used independently according to a use and a specification suitably, and may be used in mixture of multiple types.

  The positive electrode active material such as activated carbon described above is formed into a powder form, a granular form, a short fiber form, or the like. An electrode slurry is formed by dispersing the positive electrode active material and the binder in a solvent. Then, a positive electrode mixture layer is formed on the positive electrode current collector by applying and drying an electrode slurry containing the positive electrode active material on the positive electrode current collector. Examples of the binder mixed with the positive electrode active material include rubber-based binders such as SBR, fluorine-containing resins such as polytetrafluoroethylene and polyvinylidene fluoride, thermoplastic resins such as polypropylene, polyethylene, and polyacrylate, polyvinyl Alcohol can be used. As the solvent, for example, water or N-methyl-2-pyrrolidone can be used. In addition, a conductive material such as acetylene black, graphite, ketjen black, carbon black, or metal powder may be appropriately added to the positive electrode mixture layer.

[B] Negative Electrode The negative electrode has a negative electrode current collector and a negative electrode mixture layer integrated therewith. The negative electrode active material contained in the negative electrode mixture layer is not particularly limited as long as it can reversibly dope and dedope lithium ions. For example, alloy materials such as tin and silicon, oxides such as silicon oxide, tin oxide, lithium titanate, vanadium oxide, graphite (graphite), graphitizable carbon, hard carbon (non-graphitizable carbon) ) And other carbon materials, polyacene-based substances, and the like can be used. Lithium titanate is preferable as the negative electrode active material because it has excellent cycle characteristics. Tin, tin oxide, silicon, silicon oxide, graphite, and the like are preferable as the negative electrode active material because the capacity can be increased. In addition, a polyacene organic semiconductor (PAS), which is a heat-treated product of an aromatic condensation polymer, is suitable as a negative electrode active material because the capacity can be increased. This PAS has a polyacene skeleton structure. The hydrogen atom / carbon atom number ratio (H / C) of the PAS is preferably in the range of 0.05 to 0.50. When H / C of PAS exceeds 0.50, the aromatic polycyclic structure is not sufficiently developed, so that lithium ions are not doped and undoped smoothly, and the charge / discharge efficiency of the electricity storage device May decrease. When the H / C of PAS is less than 0.05, the capacity of the electricity storage device may be reduced. In addition, the negative electrode active material illustrated above may be used independently according to a use and a specification suitably, and may be used in mixture of multiple types.

  The negative electrode active material such as PAS described above is formed into a powder form, a granular form, a short fiber form, or the like. An electrode slurry is formed by dispersing the negative electrode active material, a binder, and a solvent. Then, the electrode slurry containing the negative electrode active material is applied to the negative electrode current collector and dried to form a negative electrode mixture layer on the negative electrode current collector. Examples of the binder mixed with the negative electrode active material include fluorine-containing resins such as polytetrafluoroethylene and polyvinylidene fluoride, thermoplastic resins such as polypropylene, polyethylene, and polyacrylate, polyvinyl alcohol, and carboxymethyl cellulose (CMC). ), Styrene-butadiene rubber (SBR), ethylene-propylene-diene copolymer (EPDM), and the like can be used. Among these, it is preferable to use an SBR rubber binder because high adhesiveness can be expressed with a small amount of addition. As the solvent, water, N-methyl-2-pyrrolidone, or the like can be used. In addition, a conductive material such as acetylene black, graphite, expanded graphite, carbon nanotube, vapor-grown carbon fiber, carbon black, carbon fiber, and metal powder may be added as appropriate to the negative electrode mixture layer.

[C] Positive electrode current collector and negative electrode current collector As materials for the positive electrode current collector and the negative electrode current collector, various materials generally proposed for batteries and electric double layer capacitors can be used. For example, aluminum, stainless steel, or the like can be used as a material for the positive electrode current collector. Stainless steel, copper, nickel, or the like can be used as a material for the negative electrode current collector. Moreover, when forming a through-hole in a positive electrode collector or a negative electrode collector, the opening rate of a through-hole is usually 40 to 60%. Note that the size, number, shape, and the like of the through holes are not particularly limited as long as they do not hinder the movement of lithium ions.

[D] Ion supply source Although the metal lithium foil is provided as the ion supply source, a lithium-aluminum alloy or the like may be used as the ion supply source. In the above description, a metal lithium foil obtained by rolling metal lithium is used. However, the present invention is not limited to this, and a metal lithium layer is formed on the negative electrode current collector or the negative electrode mixture layer by vapor deposition. Also good. Furthermore, an ion supply source may be provided for the negative electrode as the negative electrode composite material by including fine granular metallic lithium as an ion supply source in the negative electrode mixture layer.

[E] Separator As a separator, it has high ion permeability (air permeability), predetermined mechanical strength, durability against electrolyte solution, positive electrode active material, negative electrode active material, and the like, and has an insulating hole. A porous body or the like can be used. For example, paper (cellulose), glass fiber, polyethylene, polypropylene, polystyrene, polyester, polytetrafluoroethylene, polyvinylidene difluoride, polyimide, polyphenylene sulfide, polyamide, polyamideimide, polyethylene terephthalate, polybutylene terephthalate, polyetheretherketone For example, a cloth, a nonwoven fabric or a microporous body having a gap composed of the like is used.

  Moreover, when closing the separator, it is possible to use a pressure-sensitive adhesive tape or a polymer adhesive, but these pressure-sensitive adhesive tape or polymer adhesive does not dissolve in the electrolyte solution, and the electrolyte solution and the positive electrode active material In addition, it is preferably chemically and electrochemically stable with respect to the negative electrode active material and the like. As an adhesive tape, a polyimide adhesive tape etc. are mentioned, for example. The polymer used as the polymer adhesive is preferably a thermoplastic polymer. Specific examples include polyolefins such as polyethylene and polypropylene, polyethylene terephthalate, polyester, polyvinylidene fluoride, and polyethylene oxide. It is done. As an adhesion method, for example, a method in which a polymer adhesive is dissolved in a solvent and applied to the edge of the separator and then the solvent is removed by heating or depressurizing operation while applying pressure to the adhesive portion, or For example, a method may be used in which a polymer film containing the polymer adhesive is disposed on the edge of a separator and is bonded by heat and pressure. In particular, it is preferable to use polyvinylidene fluoride or polyethylene oxide having lithium ion conductivity because the deterioration of the electrode characteristics can be suppressed even when a polymer adhesive adheres to the electrode mixture layer. As a solvent for dissolving the polymer adhesive, it is desirable to use an organic solvent having a boiling point of 200 ° C. or less. Depending on the solubility with the polymer adhesive used, specific examples of the solvent include dimethylformamide and acetone. When the boiling point of the organic solvent exceeds 200 ° C., heating at about 100 ° C. is not preferable because it takes a long time to remove the solvent. Further, heating to 200 ° C. or higher is not preferable for safety because metallic lithium is present in the vicinity of the separator bonding portion. For the above reasons, the boiling point of the organic solvent is preferably 200 ° C. or lower, more preferably 180 ° C. or lower.

  In addition, by including these materials exemplified as polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polyester and the like in the separator, it is possible to perform a heat-sealing treatment and close the separator. The heat fusion conditions of the separator are determined by appropriately examining the heating temperature and the heating time. The heating temperature of the separator is preferably close to the melting temperature of the separator. The specific melting temperature varies depending on the material and configuration of the separator. For example, a microporous separator made of polyethylene and polypropylene owned by the inventors melts at around 110 ° C. Accordingly, when the separator is heat-sealed, the heat-sealing condition is determined by fusing the separator while changing the heating temperature and heating time at a temperature of about 110 ° C. and confirming the adhesive strength. If the heating time is short or the melting temperature is low, the separator is not sufficiently melted and insufficient adhesion is not preferable. Further, it is not preferable that the heating time is long or the melting temperature is high because the separator is bent or the separator melts to a portion in contact with the electrode composite surface to increase the resistance of the electricity storage device.

  Moreover, it is preferable that the air permeability of a separator is 5 second / 100 mL or more and 600 second / 100 mL or less. The air permeability means time (seconds) required for 100 mL of air to pass through the porous sheet. When the air permeability exceeds 600 seconds / 100 mL, it is difficult to obtain a high lithium ion mobility in the separator, which is not preferable because it impedes the lithium ion pre-doping rate. An air permeability of less than 5 seconds / 100 mL is not preferable because the strength of the separator becomes insufficient. The air permeability of the separator is more preferably 30 seconds / 100 mL to 500 seconds / 100 mL.

  The separator preferably has a porosity of 30% to 90%. When the porosity of the separator is less than 30%, the amount of electrolyte retained in the separator is reduced and the internal resistance of the electricity storage device is increased, which is not preferable. Further, if the porosity of the separator exceeds 90% or more, it is not preferable because sufficient separator strength cannot be obtained. The porosity of the separator is more preferably 35% to 80%.

  The thickness of the separator is preferably 5 μm to 100 μm. A thickness exceeding 100 μm is not preferable because the distance between the positive and negative electrodes increases and the internal resistance increases. On the other hand, when the thickness is less than 5 μm, the strength of the separator is remarkably lowered and an internal short circuit is easily generated, which is not preferable. The thickness of the separator is more preferably 10 μm or more and 30 μm or less.

  In addition, when the internal temperature of the electricity storage device reaches or exceeds the upper limit temperature of the specification, it is possible to provide the separator with the property that the separator gap is closed by the melting of the separator components (separator shutdown function). Preferred for. The blocking start temperature is usually 90 ° C. or higher and 180 ° C. or lower, although it depends on the specifications of the electricity storage device. When a material such as polyimide that has high heat resistance and is difficult to melt at the above temperature is used for the separator, it is preferable to mix a material that can be melted at the above temperature such as polyethylene. The term “mixing” as used herein includes not only simple mixing of a plurality of materials, but also means that two or more types of separators of different materials are stacked, and the separator materials are copolymerized. Note that a separator having a small thermal shrinkage even when the internal temperature of the electricity storage device exceeds the specified upper limit temperature is more preferable in terms of safety of the electricity storage device. As described above, the exemplified separators may be used singly according to the application and specifications, or the same type of separators may be used in an overlapping manner. A plurality of types of separators may be used in an overlapping manner.

[F] Electrolytic Solution As the electrolytic solution, it is preferable to use an aprotic polar solvent containing a lithium salt from the viewpoint that electrolysis does not occur even at a high voltage and that lithium ions can exist stably. Examples of the aprotic polar solvent include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, γ-butyrolactone, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, dioxolane, methylene chloride, sulfolane and the like. Or the mixed solvent is mentioned. Propylene carbonate is preferably used from the viewpoint of the relative permittivity contributing to the charge / discharge characteristics, the freezing point and boiling point contributing to the operating temperature range of the electricity storage device, and the flash point contributing to safety. However, when graphite is used as the negative electrode active material, propylene carbonate decomposes on graphite when the negative electrode potential is about 0.8 V (vs. Li ^/ Li ⁺ ), so ethylene carbonate is used as an alternative solvent. It is preferable to do. Ethylene carbonate has a melting point of 36 ° C. and is solid at room temperature. For this reason, when using ethylene carbonate as a solvent for an electrolytic solution, it is essential to mix it with an aprotic polar solvent other than ethylene carbonate. In addition, the aprotic polar solvent used in combination with ethylene carbonate has a low viscosity and a low freezing point, such as diethyl carbonate and ethyl methyl carbonate, from the viewpoint of charge / discharge characteristics and the operating temperature range of the electricity storage device. It is preferred to select a solvent. However, an electrolyte solution composed of ethylene carbonate and an aprotic polar solvent having a low viscosity and a low freezing point, such as diethyl carbonate, has a rapid ion conduction due to the solidification of ethylene carbonate when the ambient temperature is about −10 ° C. or lower. Low temperature characteristics are not good because it causes a decrease in temperature. Therefore, in order to improve the low temperature characteristics, it is preferable to include the above-mentioned propylene carbonate in the solvent of the electrolytic solution, and when graphite is used for the negative electrode active material and the conductive material, graphite having low reductive decomposability of propylene carbonate is used. It is preferable.

Examples of the lithium salt include LiClO ₄ , LiAsF ₆ , LiBF ₄ , LiPF ₆ , and LIN (C ₂ F ₅ SO ₂ ) ₂ . The electrolyte concentration in the electrolytic solution is preferably at least 0.1 mol / L or more in order to reduce the internal resistance due to the electrolytic solution. Furthermore, it is preferable to set it within the range of 0.5-1.5 mol / L. The lithium salts may be used alone or in combination.

Note that vinylene carbonate (VC), ethylene sulfite (ES), fluoroethylene carbonate (FEC), and derivatives thereof may be added to the electrolytic solution as additives for improving characteristics. The addition amount is preferably in the range of 0.01 to 10% by volume. Further, as an additive for making the electricity storage device flame-retardant, a substance such as a phosphazene compound or a derivative thereof, a fluorinated carboxylic acid ester, or a fluorinated phosphoric acid ester may be added to the electrolytic solution. Examples of the flame retardant additive include phoslite (manufactured by Nippon Chemical Industry Co., Ltd.), (CF ₃ CH ₂ O) ₃ PO, (HCF ₂ CF ₂ CH ₂ O) ₂ CO, and the like.

Further, an ionic liquid (ionic liquid) may be used instead of the organic solvent. As the ionic liquid, combinations of various cationic species and anionic species have been proposed. Examples of the cationic species include N-methyl-N-propylpiperidinium (PP13), 1-ethyl-3-methylimidazolium (EMI), diethylmethyl-2-methoxyethylammonium (DEME), and the like. Examples of the anion species include bis (fluorosulfonyl) imide (FSI), bis (trifluoromethanesulfonyl) imide (TFSI), PF ₆ ⁻ , BF ₄ ^{− and the} like.

[G] Exterior Material As the exterior material, various materials generally used for batteries can be used. For example, a metal material such as iron or aluminum may be used. Moreover, you may use film materials, such as resin. Further, the shape of the exterior material is not particularly limited. It can be appropriately selected depending on the application such as a cylindrical shape or a rectangular shape. From the viewpoint of reducing the size and weight of the electricity storage device, it is preferable to use a film-type exterior material using an aluminum laminate film. In general, a three-layer laminate film having a nylon film on the outside, an aluminum foil in the center, and an adhesive layer such as modified polypropylene on the inside is used.

  As mentioned above, although this invention was demonstrated in detail based on drawing, this invention is not limited to the said embodiment, It cannot be overemphasized that it can change variously in the range which does not deviate from the summary. For example, the structure of the electricity storage device of the present invention can be applied not only to lithium ion secondary batteries and lithium ion capacitors, but also to various types of batteries such as magnesium ion secondary batteries and hybrid capacitors thereof.

(Example)
The effectiveness of the present invention was verified using the electricity storage device having the configuration of the present invention described above. A lithium ion capacitor was used as the electricity storage device. This lithium ion capacitor includes a negative electrode composite material in which a metal lithium foil is attached on a negative electrode on the outermost part of the electrode laminate unit. The electrode laminate unit incorporates a zigzag folded separator, and the negative electrode composite material is accommodated in the negative electrode accommodating portion of the separator. Further, both end portions in the width direction of the separator folded back in a zigzag shape are closed in the stacking direction, and a folded portion provided on the opening side of the negative electrode housing portion of the separator is closed in the stacking direction. Such a lithium ion capacitor was produced as follows.

[Production method of positive electrode]
The phenolic resin was obtained activated carbon having a BET specific surface area of 2200 m ² / g by alkali activation. This activated carbon was thoroughly washed to remove residual ash and adjust pH. The activated carbon thus produced was used as a positive electrode active material.

  A paste was prepared by kneading 100 parts by weight of the positive electrode active material, 6 parts by weight of acetylene black manufactured by Denki Kagaku Kogyo Co., Ltd., and 4 parts by weight of carboxymethyl cellulose with water. The positive electrode slurry was prepared by adding the emulsion of an acrylate-type rubber binder to this paste so that it might become 6 weight part as solid content, and adding water, and adjusting a viscosity. The positive electrode slurry was applied to both surfaces of an aluminum expanded metal with a thickness of 35 μm having through holes so that the electrode thickness was 105 μm. A carbon-based conductive paint is applied to both surfaces of the aluminum expanded metal that serves as a current collecting base material.

[Production method of negative electrode]
88 parts by weight of a non-graphitizable carbon carbotron PS (F) manufactured by Kureha Co., Ltd., pulverized to a mean particle size (D50%) of 2 μm using a ball mill as a negative electrode active material, Electrochemical Co., Ltd. A paste was prepared by kneading 6 parts by weight of acetylene black special press product HS-100 and 3 parts by weight of sodium salt of carboxymethyl cellulose with water. To this paste, a latex of styrene butadiene dirubber binder was added to a solid content of 4 parts by weight, and water was added to adjust the viscosity to prepare a negative electrode slurry. This negative electrode slurry was applied to both surfaces of a 25 μm thick copper expanded metal having through holes so that the electrode thickness was 55 μm. Thus, a negative electrode was obtained.

[Preparation of electrode and separator used for cell production]
Each of the positive electrode and the negative electrode obtained as described above was dried under reduced pressure. After drying, 5 positive electrodes each having a width of 2.4 cm and a length of 3.8 cm and 6 negative electrodes each having a width of 2.6 cm and a length of 4.0 cm were cut out. . Next, a negative electrode composite material was produced by attaching a metal lithium foil having a width of 2.4 cm, a length of 3.8 cm, and a thickness of 60 μm to one surface of the cut out negative electrode.

  As a separator used for electrode lamination, a polyolefin microporous membrane separator having a thickness of 22 μm was prepared by cutting it into a size of 4.6 cm in width and 38.4 cm in length. Next, the separator was folded back every 3.2 cm from the end in the longitudinal direction of the separator to complete a zigzag stacking separator in which negative electrode accommodating portions and positive electrode accommodating portions were alternately formed.

[Production method of electrode laminate unit]
First, the negative electrode composite was accommodated in the outermost negative electrode accommodating portion in the zigzag separator. Next, the positive electrode was accommodated in the positive electrode accommodating part of the inner layer of the negative electrode accommodating part which accommodated the said negative electrode composite. Furthermore, the negative electrode was accommodated in the negative electrode accommodating part of the inner layer of the positive electrode accommodating part in which the positive electrode was accommodated similarly to accommodation of the positive electrode in the positive electrode accommodating part. Thus, each electrode is accommodated so as to be a negative electrode composite, a positive electrode, a negative electrode, a positive electrode, a negative electrode,..., A negative electrode with respect to a zigzag stacking separator in which a negative electrode accommodating portion and a positive electrode accommodating portion are alternately formed. An electrode laminate unit was obtained by accommodating an electrode in the part. In order to prevent displacement of the electrode in the electrode laminate unit, the width direction of the electrode laminate unit is sandwiched between two polypropylene plates (width 1.5 cm, length 6.4 cm), and both ends of the polypropylene plate are The electrode laminate unit was fixed by sandwiching with clips.

  Next, by using a chamber type degassing sealer FCB-200 manufactured by Fuji Impulse Co., Ltd., both ends in the width direction of the separator folded back in a zigzag shape were subjected to heat and pressure and closed in the stacking direction. Furthermore, after releasing the fixing of the electrode stacking unit by the clip and the polypropylene plate, the folded portion of the separator provided on the opening side of the negative electrode housing portion was closed in the stacking direction by performing heat heating using the degassing sealer. . As described above, the electrode laminate unit incorporated in the electricity storage device of the present invention was completed.

[Cell fabrication method]
A positive electrode terminal was disposed and welded to the terminal joint portion of the positive electrode current collector, and a negative electrode terminal was disposed and welded to the terminal joint portion of the negative electrode current collector. Further, as a reference electrode for measuring the positive and negative electrode potentials in the electricity storage device, a lithium metal electrode was bonded to a stainless mesh having a thickness of 120 μm and a nickel terminal was welded to the stainless mesh to produce a lithium electrode. Next, the lithium electrode is disposed on the outermost one surface of the electrode laminate unit, the outer periphery of the electrode laminate unit and the lithium electrode is covered with a 35 μm thick paper separator, and the overlapped portion of the separator is fixed with a polyimide adhesive tape. A lithium ion capacitor element was completed.

Next, the lithium ion capacitor element was covered with an aluminum laminate film as an exterior material, and three sides of the aluminum laminate film were heated and fused. Thereafter, an electrolytic solution prepared by dissolving LiPF ₆ in propylene carbonate so as to have a concentration of 1.2 mol / L was poured into an aluminum laminate film and impregnated through a vacuum impregnation step. And 100 cells of the lithium ion capacitor used as an Example were produced by vacuum-sealing the remaining one side of an aluminum laminate film.

(Comparative example)
A zigzag separator is sandwiched between the electrodes of the electrode stacking unit, and this separator is not closed in the stacking direction. Moreover, in order to fix an electrode laminated unit, the polyimide adhesive tape was affixed on a part of edge part of an electrode laminated unit. About the structure of those other than these, 100 cells of the lithium ion capacitor used as a comparative example were produced just like the lithium ion capacitor of an Example.

(Examination of Examples and Comparative Examples)
Lithium ion pre-doping was terminated by allowing the lithium ion capacitor cells produced in Examples and Comparative Examples to stand at room temperature for 2 weeks. As for the cell of the comparative example, 29 cells were expanded and became defective cells. When the potentials of the positive electrode and the negative electrode were confirmed using the lithium electrode, it was confirmed that the potential of the positive electrode was significantly lower than 2 V (vs. Li ^/ Li ⁺ ). It is considered that a metal lithium piece dropped from the metal lithium comes into contact with the positive electrode (short circuit), and the positive electrode potential is lowered, so that gas resulting from reductive decomposition of the electrolytic solution is generated on the positive electrode. On the other hand, in the cell of the example, the cell in the above-described state was not seen at all. Table 1 shows the results of measuring the cell voltage, positive electrode potential, and negative electrode potential of 100 cells of the example in which no cell expansion was observed and 71 cells of the comparative example. Although the cell of the example has a larger number of measurement samples, it can be confirmed that variations in cell voltage, positive electrode potential, and negative electrode potential are smaller. In the cell of the comparative example, it is presumed that there is a cell that does not reach the cell expansion but may cause the micro short circuit.

  Next, 10 cells were arbitrarily extracted from the cells of the example and the comparative example, and the inside of the cell was investigated by disassembling the cell. About the cell of the comparative example, it was confirmed that the microparticles | fine-particles which have the metallic luster considered to be metallic lithium exist from electrolyte solution other than the place which installed the negative electrode composite material, or the electrode laminated unit. Accordingly, it can be seen that the cell of the comparative example has a risk that the predetermined lithium ion pre-doping amount cannot be doped into the negative electrode due to liberation of metallic lithium and that the cell suddenly shorts. On the other hand, the presence of a substance considered to be metallic lithium was not recognized from the cell of the example. From the above, it was shown that the cell of the example having the configuration of the present invention is excellent in quality.

DESCRIPTION OF SYMBOLS 10 Power storage device 13 Positive electrode 14 Negative electrode 15 Negative electrode (negative electrode composite material)
16 Metal lithium foil (ion source)
17 Separator 17a Both ends 17b Folded portion 20 Positive electrode current collector 20a Through hole 21 Positive electrode mixture layer 23 Negative electrode current collector 23a Through hole 24 Negative electrode mixture layer 26 Positive electrode housing portion 27 Negative electrode housing portion 31 Separator 31a Both end portions 31b Folded portion 32 Positive electrode housing part 33 Negative electrode housing part 40 Separator 40a Extension part 40b Negative electrode housing part 40c Folding part 43 Separator 43a First extension part (extension part)
43b Second extension (extension)
43c Negative electrode housing part 43d Folding part 46 Separator 46a First extension part (extension part)
46c Negative electrode accommodating portion 46d Folded portion 46e Positive electrode accommodating portion 50 Power storage device 52 Positive electrode 53 Negative electrode (negative electrode composite material)
54 Positive Current Collector 55 Negative Current Collector 56 Metal Lithium Foil (Ion Supply Source)

Claims (6)

A power storage device in which a positive electrode including a positive electrode current collector and a positive electrode mixture layer and a negative electrode including a negative electrode current collector and a negative electrode mixture layer are alternately stacked,
A strip-shaped separator that is folded back in a zigzag shape and alternately forms a positive electrode housing portion that houses the positive electrode and a negative electrode housing portion that houses the negative electrode,
At least one of the negative electrodes is configured as a negative electrode composite material including an ion supply source in addition to the negative electrode current collector and the negative electrode mixture layer,
Both ends of the separator in the width direction are closed in the stacking direction under a zigzag folded state. The electricity storage device according to claim 1, wherein
The electricity storage device, wherein the folded portion of the separator provided on the opening side of the negative electrode accommodating portion is closed in the stacking direction. The electricity storage device according to claim 1 or 2,
The electricity storage device, wherein a folded portion of the separator provided on the opening side of the negative electrode accommodating portion is covered with an extension provided at an end portion in the longitudinal direction of the separator. In the electrical storage device of any one of Claims 1-3,
An electric storage device, wherein an outer edge of the ion supply source is disposed on an inner side than an outer edge of the negative electrode current collector. In the electrical storage device of any one of Claims 1-4,
A power storage device, wherein the positive electrode current collector and the negative electrode current collector are formed with a plurality of through holes. A method for producing an electricity storage device in which a positive electrode including a positive electrode current collector and a positive electrode mixture layer and a negative electrode including a negative electrode current collector and a negative electrode mixture layer are alternately laminated,
Folding the strip-shaped separator into a zigzag shape, and alternately forming a positive electrode housing portion for housing the positive electrode and a negative electrode housing portion for housing the negative electrode;
A step of forming at least one of the negative electrodes into a negative electrode composite material including an ion supply source in addition to the negative electrode current collector and the negative electrode mixture layer;
And a step of closing both end portions in the width direction of the separator in a stacking direction under a state of being folded back in a zigzag shape.

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