JP2017123385A - Power storage device and power-storage module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device which can suppress the worsening of cycle characteristics.SOLUTION: A power storage device 10 comprises: an electrode unit 20 including a positive electrode plate 21 and a negative electrode plate 22; a lithium-supplying plate 30 for supplying lithium ions to the negative electrode plate 22; a positive electrode terminal 60 electrically connected with the positive electrode plate 21; and a negative electrode terminal 70 electrically connected with the negative electrode plate 22, and electrically connected with the lithium-supplying plate 30 through a resistor 40. The resistor 40 is 50-500 Ω in electric resistance value.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a power storage device such as a secondary battery or a capacitor, and a power storage module including a plurality of power storage devices.

  It has a laminate in which negative and positive electrodes are alternately stacked, and a lithium electrode electrically connected to the negative electrode, and is doped with lithium ions from the lithium electrode before the charging operation between the positive and negative electrodes An electric storage device (also referred to as pre-doping) is known (see, for example, Patent Document 1).

JP 2013-258422 A

  In general, in a power storage device that performs pre-doping, before lithium ions are doped into the negative electrode, the electrolytic solution undergoes a reductive decomposition reaction at the negative electrode, and an interelectrode substance (Solid Electrolyte Interface, SEI) is formed on the surface of the negative electrode. It is formed. By uniformly forming the SEI on the surface of the negative electrode, the negative electrode is uniformly doped with lithium ions during the subsequent charge / discharge operation. However, in the above electricity storage device, since the negative electrode and the lithium electrode are directly connected, an excessive current flows between the negative electrode and the lithium electrode immediately after the start of pre-doping, and homogeneous SEI is formed on the surface of the negative electrode. It is hard to be done. For this reason, doping of lithium ions to the negative electrode may not be performed evenly during subsequent charge / discharge operations. In this case, there exists a problem that a negative electrode becomes easy to deteriorate and there exists a possibility that the cycling characteristics of an electrical storage device may fall.

  The problem to be solved by the present invention is to provide a power storage device capable of suppressing a decrease in cycle characteristics and a power storage module including the power storage device.

[1] An electricity storage device includes an electrode unit including a positive electrode plate and a negative electrode plate, a lithium supply plate that supplies lithium ions to the negative electrode plate, a positive electrode terminal that is electrically connected to the positive electrode plate, and the negative electrode plate And a negative electrode terminal electrically connected to the lithium supply plate via a resistor, and the resistor has an electrical resistance value of 50Ω to 500Ω.

[2] In the above invention, the negative electrode plate includes a first current collector, and the first current collector includes a first main body portion that holds a layer containing a negative electrode active material, and the first current collector. A first lead portion extending from the main body portion, and the lithium supply plate further includes a second current collector and a lithium supply source, and the second current collector is the lithium supply source. And a second lead portion extending from the second body portion, and the resistor electrically connects the resistor body portion and the resistor body portion to the outside. First and second connecting portions, wherein the first lead portion is joined to the negative terminal, and the second lead portion is joined to the first connecting portion. And the second connecting portion is joined to the negative electrode terminal at a portion different from a joint portion between the first lead portion and the negative electrode terminal. It may be.

[3] The power storage module includes two or more power storage devices, and each of the power storage devices is a power storage module connected in series or in parallel.

  In the present invention, the negative electrode terminal and the negative electrode plate are electrically connected, and the negative electrode terminal and the lithium supply plate are electrically connected via a resistor, and the electric resistance value of the resistor is 50Ω to 500Ω. Thereby, when performing pre dope, it can suppress that an excessive electric current flows between the said negative electrode plate and a lithium supply board. As a result, during the subsequent charge / discharge operation, the negative electrode is unlikely to deteriorate, and a reduction in cycle characteristics of the electricity storage device can be suppressed.

FIG. 1 is a plan view showing an electricity storage device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. FIG. 3 is an enlarged plan view of a joint portion between the positive electrode plate and the positive electrode terminal of the electrode unit according to the embodiment of the present invention as viewed from above. FIG. 4 is an enlarged plan view of a joint portion between the negative electrode plate and the negative electrode terminal of the electrode unit according to the embodiment of the present invention as viewed from below. FIG. 5 is an enlarged plan view of a joint portion between a lithium supply plate and a negative electrode terminal according to an embodiment of the present invention as viewed from below. FIG. 6A and FIG. 6B are diagrams for explaining the operation of the electricity storage device according to the embodiment of the present invention. FIG. 7 is a perspective view showing the power storage module in the embodiment of the present invention. FIG. 8 is an equivalent circuit diagram of the power storage module shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in this specification, "-" which shows a numerical range is used as the meaning containing the numerical value described before and behind that as an upper limit and a lower limit.

  1 is a plan view showing an electricity storage device according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1, and FIG. 3 is an electrode unit according to an embodiment of the present invention. FIG. 4 is an enlarged plan view of a joining portion between a negative electrode plate and a negative electrode terminal of an electrode unit according to an embodiment of the present invention, as viewed from below. FIG. 5 is an enlarged plan view of a joint portion between the lithium supply plate and the negative electrode terminal according to the embodiment of the present invention as viewed from below. In FIG. 3, for convenience of explanation, other electrode plates and separators located above the illustrated positive electrode plate 21 (+ Z axis direction side in the figure) are not shown. Further, in FIG. 4, for convenience of explanation, the separator and the lithium supply plate located below the illustrated negative electrode plate 22 (the −Z axis direction side in the drawing) are not illustrated.

  As shown in FIGS. 1 and 2, the electricity storage device 10 in this embodiment is a flat lithium ion capacitor. This power storage device 10 is used as a power source for supplying power to, for example, a lamp or a motor mounted on a vehicle. In addition, the use of the electricity storage device 10 is not particularly limited to the above. The electricity storage device 10 of this embodiment is an electricity storage device that performs so-called pre-doping, in which lithium ions are doped from the lithium supply plate 30 to the negative electrode plate 22 before performing the first charging operation between the positive and negative electrodes. In the electricity storage device 10, by performing pre-doping, the negative electrode potential is lowered, and the output voltage of the electricity storage device 10 is improved. In such an electricity storage device 10, the negative electrode plate 22 is doped with lithium ions during charging, and the lithium ions are dedoped from the negative electrode plate 22 during discharging. In the present embodiment, “doping” refers to a phenomenon in which lithium ions are occluded in the negative electrode plate 22 (specifically, the negative electrode active material layer 224 (described later)). On the other hand, “de-doping” refers to a phenomenon in which lithium ions are released from the negative electrode plate 22 (specifically, the negative electrode active material layer 224).

  As shown in FIG. 2, the electricity storage device 10 includes an electrode unit 20 including a positive electrode plate 21 and a negative electrode plate 22, a lithium supply plate 30, a resistor 40, an electrode unit 20, a lithium supply plate 30, and a resistor. The exterior member 50 which accommodates 40, and the positive electrode terminal 60 and the negative electrode terminal 70 which are electrically connected to the electrode unit 20, and are extended from the inner side to the outer side of the exterior member 50 are provided. The exterior member 50 is filled with an electrolytic solution (not shown).

  The electricity storage device 10 in the present embodiment corresponds to an example of the “electric storage device” in the present invention, the “positive electrode plate 21” in the present embodiment corresponds to an example of the “positive electrode plate” in the present invention, and the “negative electrode in the present embodiment” The “plate 22” corresponds to an example of the “negative electrode plate” in the present invention, the “electrode unit 20” in the present embodiment corresponds to an example of the “electrode unit” in the present invention, and the “lithium supply plate 30” in the present embodiment. Corresponds to an example of “lithium supply plate” in the present invention, “resistor 40” in the present embodiment corresponds to an example of “resistor” in the present invention, and “positive electrode terminal 60” in the present embodiment corresponds to the present invention. The “negative terminal 70” in the present embodiment corresponds to an example of the “negative terminal” in the present invention.

  In addition, the external shape of the electrical storage device 10 is not limited to a flat shape, and may be a cylindrical shape, a box shape, or the like. Further, the electricity storage device according to the present invention is not limited to the above-described lithium ion capacitor, and may be, for example, a lithium ion secondary battery.

  The electrode unit 20 in this embodiment includes a plurality of positive plates 21, a plurality of negative plates 22, and a plurality of separators 23. The positive electrode plates 21 and the negative electrode plates 22 are alternately stacked with separators 23 interposed therebetween. In addition, the number of the positive electrode plate 21, the negative electrode plate 22, and the separator 23 which comprise the electrode unit 20 is not specifically limited.

  As shown in FIG. 2, each positive electrode plate 21 includes a positive electrode current collector 211 and a positive electrode active material layer 214 provided on both surfaces of the positive electrode current collector 211. For the uppermost positive electrode plate 21, the positive electrode active material layer 214 is provided only on the lower surface of the positive electrode current collector 211.

  As shown in FIGS. 2 and 3, the positive electrode current collector 211 of the positive electrode plate 21 has a main body portion 212 and a lead portion 213. The main body portion 212 is a plate-like member that holds the positive electrode active material layer 214, and the positive electrode active material layer 214 is provided on both surfaces of the main body portion 212. Although it does not specifically limit as thickness of such a main-body part 212, It is preferable that it is 2-100 micrometers, It is more preferable that it is 5-80 micrometers, It is still more preferable that it is 10-50 micrometers.

  A large number of through holes 212 a are formed in the main body 212 over the entire main surface. This through-hole 212a functions as a movement path for the electrolyte and lithium ions to move smoothly in the electricity storage device 10. The diameter of the through-hole 212a is not particularly limited, but is preferably 1 to 500 μm, and more preferably 1 μm to 200 μm.

  Specifically, the main body 212 is made of expanded metal, punching metal, a net, a foam, or the like. Moreover, as a material which comprises such a main-body part 212, the metal material generally applicable to a lithium-type battery can be used, Specifically, aluminum, stainless steel, etc. can be used.

  The main body portion 212 of the present embodiment is substantially rectangular, and a strip-shaped lead portion 213 extends from the approximate center of one short side of the main body portion 212 in a direction away from the main body portion 212. In the present embodiment, the lead portion 213 is formed integrally with the main body portion 212, but is not particularly limited to this, and the lead portion 213 is not limited to this, as long as the main body portion 212 and the lead portion 213 are electrically connected. May be prepared in advance and joined to the main body 212 by welding or the like.

  The leading end 213a of this lead portion 213 (the end opposite to the side connected to the main body portion 212) is bent so as to be a joint allowance with the positive terminal 60 and the lead portion 213 of the other positive plate 21. In the plurality of positive electrode plates 21, the lead portions 213 of the respective positive electrode current collectors 211 extend from the short sides on the same side of the main body portions 212. The tips 213a of the plurality of lead portions 213 are arranged side by side in the stacking direction (Y direction in the figure) of the electrode units 20, and are joined together by welding or the like.

  The positive electrode active material layer 214 of the positive electrode plate 21 is formed by applying a slurry containing a positive electrode active material, a conductive material, a binder, a dispersant, and the like to the main surface of the positive electrode current collector 211 and drying it. The thickness of the positive electrode active material layer 214 is not particularly limited, but is preferably 10 to 150 μm. In addition, at the time of manufacturing the positive electrode plate 21, the viscosity of the slurry is preferably 50 to 1800 mPas from the viewpoint of more reliably holding the positive electrode active material layer 214 on the main surface of the positive electrode plate 21.

  The positive electrode active material contained in the positive electrode active material layer 214 is formed of a material capable of reversibly occluding and releasing lithium ions and anions. For example, activated carbon such as phenol resin activated carbon, coconut shell activated carbon and petroleum coke activated carbon having polarizability, and carbon materials such as polyacene can be used. When using the above-mentioned activated carbon as a positive electrode active material, the particle size of the activated carbon is not particularly limited, but is preferably 2 to 20 μm, and more preferably 2 to 15 μm.

  As the conductive material contained in the positive electrode active material layer 214, for example, carbon black such as acetylene black and ketjen black, graphite, and metal powder can be used. In this case, in the positive electrode active material layer 214, the ratio of the weight of the conductive material to the weight of the positive electrode active material is preferably 2 to 40% (2 to 40 wt%).

  As the binder, for example, a rubber-based binder such as SBR, a fluorine-containing resin such as polyvinylidene fluoride, a thermoplastic resin such as polypropylene, an acrylic resin, or the like can be used. In this case, in the positive electrode active material layer 214, the ratio of the weight of the binder to the weight of the positive electrode active material is preferably 2 to 40% (2 to 40 wt%).

  As the dispersant, carboxymethyl cellulose salt or the like can be used. In this case, in the positive electrode active material layer 214, the ratio of the weight of the dispersant to the weight of the positive electrode active material is preferably 2 to 40% (2 to 40 wt%).

  As shown in FIG. 3, the positive electrode active material layer 214 has an outer shape smaller than that of the main body 212 in a plan view. In this case, the through hole 212 a is also present outside the outer edge portion 214 a of the positive electrode active material layer 214. For this reason, electrolyte solution and lithium ion can be uniformly supplied to the entire positive electrode active material layer 214. Note that the positive electrode active material layer 214 may be formed on the entire surface of the main body 212. In this case, the through hole 212 a does not exist outside the outer edge portion 214 a of the positive electrode active material layer 214. Further, the through hole 212a is formed in the positive electrode active material layer 214 without changing the relative relationship between the outer shape of the main body portion 212 and the positive electrode active material layer 214 (the relationship in which the outer shape of the positive electrode active material layer 214 is smaller than the outer shape of the main body portion 212). You may form only in the inner side of the outer edge part 214a. Also in this case, the through hole 212 a does not exist outside the outer edge portion 214 a of the positive electrode active material layer 214.

  As shown in FIG. 2, each negative electrode plate 22 also includes a negative electrode current collector 221 and negative electrode active material layers 224 provided on both surfaces of the negative electrode current collector 221. The “negative electrode current collector 221” in the present embodiment corresponds to an example of the “first current collector” in the present invention, and the “negative electrode active material layer 224” in the present embodiment includes the “negative electrode active material” in the present invention. It corresponds to an example of “layer”.

  As shown in FIGS. 2 and 4, the negative electrode current collector 221 of the negative electrode plate 22 has a main body portion 222 and a lead portion 223. The “main body portion 222” in the present embodiment corresponds to an example of the “first main body portion” in the present invention, and the “lead portion 223” in the present embodiment corresponds to an example of the “first lead portion” in the present invention. To do.

  The main body portion 222 is a plate-like member that holds the negative electrode active material layer 224, and the negative electrode active material layer 224 is provided on both surfaces of the main body portion 222. Although it does not specifically limit as thickness of such a main-body part 222, It is preferable that it is 2-100 micrometers, It is more preferable that it is 5-80 micrometers, It is still more preferable that it is 10-50 micrometers.

  A large number of through holes 222a are formed in the main body 222 over the entire main surface. The through hole 222a functions as a movement path for the electrolytic solution and lithium ions to move smoothly in the electricity storage device 10. The diameter of the through hole 222a is not particularly limited, but is preferably 1 to 500 μm, and more preferably 1 μm to 150 μm.

  Specifically, the main body 222 is made of an expanded metal, a punching metal, a net, a foam, or the like. Moreover, as a material which comprises this main-body part 222, the metal material generally applicable to a lithium battery can be used, Specifically, stainless steel, copper, nickel, etc. can be used.

  The main body portion 222 of the present embodiment has a substantially rectangular shape, and a strip-shaped lead portion 223 extends in a direction away from the main body portion 222 from the approximate center of one short side of the main body portion 222. The lead portion 223 extends from the short side of the main body portion 222 opposite to the side where the lead portion 213 extends from the main body portion 212 of the positive electrode plate 21. In the present embodiment, the lead portion 223 is formed integrally with the main body portion 222, but is not particularly limited to this. If the main body portion 222 and the lead portion 223 are electrically connected, the lead portion 223 is formed. May be prepared in advance and joined to the main body portion 222 by welding or the like.

  The leading end 223a of the lead portion 223 (the end opposite to the side connected to the main body portion 222) is bent so as to be a joint allowance with the negative electrode terminal 70 or the lead portion 223 of another negative electrode plate 22. In the plurality of negative electrode plates 22, the lead portions 223 of the respective negative electrode current collectors 211 extend from the short sides on the same side of the main body portions 222. The tips 223a of the plurality of lead portions 223 are arranged side by side in the stacking direction (+ Z axis direction side in the drawing) of the electrode units 20, and are joined together by welding or the like.

  The negative electrode active material layer 224 of the negative electrode plate 22 is formed by applying a slurry obtained by mixing a negative electrode active material, a conductive material, a binder, a dispersant, and the like to the surface of the negative electrode current collector 221 and drying it. The thickness of the negative electrode active material layer 224 is not particularly limited, but is preferably 10 to 150 μm. In addition, at the time of manufacturing the negative electrode plate 22, the viscosity of the slurry is preferably 50 to 1800 mPas from the viewpoint of more reliably holding the negative electrode active material layer 224 on the main surface of the negative electrode plate 22.

  The negative electrode active material contained in the negative electrode active material layer 224 is not particularly limited as long as it can reversibly occlude and release lithium ions. For example, hard carbon or graphite can be used. In this case, the particle size of the negative electrode active material is not particularly limited, but is preferably 2 to 20 μm.

  As the conductive material, binder, and dispersant contained in the negative electrode active material layer 224, the same materials as those constituting the positive electrode active material layer 214 can be used. Note that the hard carbon or graphite, which is the negative electrode active material included in the negative electrode active material layer 224, has high electrical conductivity, and thus the conductive material may be omitted from the negative electrode active material layer 224.

  Note that as in the positive electrode active material layer 214, in the negative electrode active material layer 224, the ratio of the weight of the conductive material to the weight of the negative electrode active material is preferably 2 to 40% (2 to 40 wt%). The ratio of the weight of the binder to the weight of the negative electrode active material is preferably 2 to 40% (2 to 40 wt%). The ratio of the weight of the dispersant to the weight of the negative electrode active material is preferably 2 to 40% (2 to 40 wt%).

  As shown in FIG. 4, such a negative electrode active material layer 224 has an outer shape smaller than that of the main body 222 in a plan view. In this case, the through hole 222 a is also present outside the outer edge portion 224 a of the negative electrode active material layer 224. For this reason, electrolyte solution and lithium ion can be uniformly supplied to the entire negative electrode active material layer 224. Note that the negative electrode active material layer 224 may be formed on the entire surface of the main body portion 222. In this case, the through hole 222 a does not exist outside the outer edge portion 224 a of the negative electrode active material layer 224. Further, the through hole 222a is formed in the negative electrode active material layer 224 without changing the relative relationship between the outer shape of the main body portion 222 and the negative electrode active material layer 224 (the relationship in which the outer shape of the negative electrode active material layer 224 is smaller than the outer shape of the main body portion 222). You may form only in the inner side of the outer edge part 224a. Also in this case, the through hole 222 a does not exist outside the outer edge portion 224 a of the negative electrode active material layer 224.

  Returning to FIG. 2, the separator 23 is made of a porous body that is durable against an electrolytic solution, a positive electrode active material, a negative electrode active material, and the like and has continuous air holes and has no electronic conductivity. Specifically, the separator 23 is composed of a nonwoven fabric or a microporous film formed from cellulose, polyethylene, or the like. Although the thickness of such a separator 23 is not specifically limited, It is preferable that it is 10-50 micrometers. The positive electrode active material layer 214, the negative electrode active material layer 224, and the separator 23 are impregnated with an electrolytic solution.

  As a solvent constituting the electrolytic solution, an aprotic organic solvent is preferably used. As this aprotic organic solvent, for example, carbonates such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate can be used. You may use the liquid mixture which mixed 2 or more types of these aprotic organic solvents.

In the electrolytic solution, any electrolyte can be used as long as it can generate lithium ions as the electrolyte dissolved in the solvent. Examples of such an electrolyte include lithium salts such as LiBF ₄ , LiPF _6, LiFSI, _and LiTFSI, but LiPF ₆ is preferably used from the viewpoint of reducing resistance in the electrolytic solution.

  The lithium supply plate 30 is a lithium electrode including a lithium electrode current collector 31 and a lithium supply source 32. The lithium supply plate 30 is accommodated in the exterior member 50 as in the electrode unit 20. The lithium supply plate 30 is disposed on the lower side of the electrode unit 20 via the separator 23. The “lithium electrode current collector 31” in the present embodiment corresponds to an example of the “second current collector” in the present invention, and the “lithium supply source 32” in the present embodiment corresponds to the “lithium supply source” in the present invention. It corresponds to an example.

  As shown in FIGS. 2 and 5, the lithium electrode current collector 31 of the lithium supply plate 30 includes a main body portion 311 and a lead portion 312. The “main body portion 311” in the present embodiment corresponds to an example of the “second main body portion” in the present invention, and the “lead portion 312” in the present embodiment corresponds to an example of the “second lead portion” in the present invention. To do.

  The main body 311 is a plate-like member that holds the lithium supply source 32. Specifically, the main body 311 is configured by a metal foil or metal plate made of copper or stainless steel in which a large number of through holes 311a are formed. The thickness of such a lithium electrode current collector 31 is not particularly limited, but is preferably 10 to 40 μm. Note that when the lithium supply plate 30 is disposed on the outermost side of the electrode unit 20 as in the present embodiment, the main body 311 may not have the through hole 311a.

  The main body portion 311 of the present embodiment is substantially rectangular, and a strip-shaped lead portion 312 extends from the approximate center of one short side of the main body portion 311 in a direction away from the main body portion 311. The lead portion 312 extends from the short side of the main body portion 311 on the same side as the side where the lead portion 223 extends from the main body portion 222 of the negative electrode plate 22, and faces toward the center of the electricity storage device 10 in a cross-sectional view. It is bent gently. In the present embodiment, the lead portion 312 is integrally formed with the main body portion 311, but is not particularly limited thereto, and the lead portion 312 is not limited to this, as long as the main body portion 311 and the lead portion 312 are electrically connected. May be prepared in advance and joined to the main body 311 by welding or the like.

  The lithium supply source 32 has a function of supplying lithium ions to the negative electrode plate 22 of the electrode unit 20. The lithium supply source 32 is a metal foil that is crimped onto the lithium electrode current collector 31. The lithium supply source 32 is made of a material containing at least lithium and capable of supplying lithium ions. Specific examples of the material constituting the lithium supply source 32 include a lithium-aluminum alloy.

  The lithium supply plate 30 is not limited to the form shown in the figure. For example, although not particularly illustrated, (1) a configuration in which a separator 23 is further provided on the uppermost positive electrode plate 21 and a lithium supply plate 30 is further added on the separator 23, and (2) a central region of the electrode unit 20 is provided. A configuration in which separators 23 and 23 are provided between two electrode plates (including the positive electrode plate 21 and the negative electrode plate 22), and two lithium supply plates 30 are added between the separators 23 and 23, (3) cylinder It is good also as a form applied to the shape electrical storage device. If the lithium supply plate 30 is not short-circuited with the electrode unit 20, the separator between the lithium supply plate 30 and the electrode unit 20 may be omitted.

  As shown in FIG. 2, the resistor 40 is housed in the exterior member 50 in the same manner as the electrode unit 20 and the lithium supply plate 30. As shown in FIGS. 2 and 5, the resistor 40 includes a resistor main body 41 and lead portions 42 and 43. The “resistor body portion 41” in the present embodiment corresponds to an example of the “resistor body portion” in the present invention, and the “lead portion 42” in the present embodiment corresponds to an example of the “first connection portion” in the present invention. The “lead portion 43” in the present embodiment corresponds to an example of the “second connection portion” in the present invention.

  The surface of the resistance main body 41 is coated with a material that is durable against an electrolytic solution, a positive electrode active material, a negative electrode active material, and the like. The shape of the resistor main body 41 is not particularly limited, and a shape such as a substantially rectangular shape or a substantially cylindrical shape can be employed. The resistance main body 41 of this embodiment is substantially cylindrical.

  The lead parts 42 and 43 are linear or belt-like members and are electrically connected to the resistance main body part 41. The lead portion 42 extends from one end of the substantially cylindrical resistance main body portion 41. The leading end 42 a of the lead portion 42 is bent so as to be a joint allowance with the lead portion 312 of the lithium supply plate 30. At the tip 42a, the lead part 42 and the lead part 312 of the lithium supply plate 30 are joined by welding or the like.

  The lead portion 43 extends from the other end of the substantially cylindrical resistance main body portion 41. The leading end 43 a of the lead portion 43 is bent so as to be a joining margin with the negative electrode terminal 70. At the tip 43a, the lead portion 43 and the negative terminal 70 are joined by welding or the like.

  Such lead parts 42 and 43 are comprised with the material which has durability with respect to electrolyte solution, a positive electrode active material, a negative electrode active material, etc., electrical conductivity, and flexibility. Specifically, a metal material such as copper can be used for the lead portions 42 and 43.

  As such a resistor 40, a fixed resistor such as a carbon resistor or a metal film resistor can be used. In this embodiment, the electrical resistance value of the resistor 40 is set within a range of 50 to 500Ω. In addition, it is more preferable that the electrical resistance value of the resistor 40 is set within a range of 50 to 200Ω. Since the electrical resistance values of the lead portions 42 and 43 are much smaller than the electrical resistance value of the resistance main body portion 41, the electrical resistance value of the resistor 40 can be approximately approximate to the electrical resistance value of the resistance main body portion 41. it can.

  In this embodiment, the so-called axial type resistor 40 in which the lead portions 42 and 43 extend from both ends of the resistor main body 41 is used. However, the present invention is not limited to this, and extends in parallel from the same side of the resistor main body 41. A so-called radial type resistor having two lead portions may be used. In addition, the resistor 40 may not have the lead portions 42 and 43 as long as the resistor 40 has a connection portion that can electrically connect the resistor main body portion 41 to the outside.

  As shown in FIGS. 1 and 2, the exterior member 50 includes an upper member 51 and a lower member 52. The upper member 51 is formed by molding a laminate film, and has a recess 511 in the center that can accommodate the electrode unit 20 described above. Similarly, the lower member 52 is formed by molding a laminate film, and has a concave portion 521 that can accommodate the electrode unit 20 in the center.

  As shown in the enlarged view of FIG. 2, the laminate film constituting the upper member 51 and the lower member 52 is a metal foil 50a made of aluminum, stainless steel, or the like, and laminated on both surfaces of the metal foil 50a. 1 and 2nd resin film 50b, 50c, and has moderate flexibility. The 1st resin film 50b laminated | stacked on the inner surface of the metal foil 50a is comprised from the resin material excellent in electrolyte solution resistance and heat-fusion property. On the other hand, the 2nd resin film 50c laminated | stacked on the outer surface of the metal foil 50a is comprised from the resin material excellent in electrical insulation. Examples of the material constituting the first and second resin films 50b and 50c include polypropylene, polyethylene, polybutylene terephthalate, and nylon.

  The outer peripheral edge of the upper member 51 and the outer peripheral edge of the lower member 52 are joined together by heat-sealing the first resin film 50b. As a result, a sealing portion 53 that seals the exterior member 50 is formed over the entire circumference of the exterior member 50, and the electrode unit 20 and the lithium supply are supplied to a space formed by the recesses 511 and 521 arranged to face each other. The plate 30 and the resistor 40 are accommodated.

  As shown in FIGS. 1 to 3, the positive electrode terminal 60 is a plate-like member extending from the inside to the outside of the exterior member 50. The end portion 61 of the positive electrode terminal 60 is exposed from one end portion of the exterior member 50 toward the outside of the exterior member 50. The end 62 of the positive electrode terminal 60 is located inside the exterior member 50. In the vicinity of the end portion 62, the lead portion 213 of the positive electrode plate 21 of the electrode unit 20 is joined by welding or the like. The positive electrode terminal 60 is made of a base material made of a metal mainly composed of aluminum, that is, aluminum or an aluminum alloy. A plating layer such as nickel or tin, a clad nickel layer, or the like may be formed on the surface of the substrate.

  As shown in FIGS. 1 and 2, the negative electrode terminal 70 extends from the inside to the outside of the exterior member 50. The end 71 of the negative electrode terminal 70 is exposed from the other end of the exterior member 50 toward the outside of the exterior member 50. An end 72 of the negative electrode terminal 70 is located inside the exterior member 50.

  As shown in FIGS. 2, 4, and 5, the lead portion 223 of the negative electrode plate 22 and the lead portion 43 of the resistor 40 are connected to the end portion 72 of the negative electrode terminal 70 at different portions by welding or the like. It is joined. Specifically, the lead portion 223 of the negative electrode plate 22 is joined in the vicinity of the end portion 72 of the negative electrode terminal 70. The lead portion 43 of the resistor 40 is joined to a portion located closer to the end portion 71 than the joint portion between the negative electrode terminal 70 and the lead portion 223 of the negative electrode plate 22. The lead part 312 of the lithium supply plate 30 is connected to the lead part 42 of the resistor 40. In the electricity storage device 10, the negative electrode plate 22 of the electrode unit 20 and the lithium supply plate 30 are electrically connected via the resistor 40 and the negative electrode terminal 70.

  The negative electrode terminal 70 is made of a base material made of a metal mainly composed of copper, that is, copper or a copper alloy. In order to prevent oxidation of the base material, a plating layer such as nickel or tin, a clad nickel layer, or the like may be formed on the surface of the negative electrode terminal 70. The outer shape and thickness of the positive electrode terminal 60 and the negative electrode terminal 70 can be appropriately selected according to the specifications of the electricity storage device 10.

  Next, the operation of the electricity storage device 10 of this embodiment will be described.

  FIG. 6A and FIG. 6B are diagrams for explaining the operation of the electricity storage device according to the embodiment of the present invention.

  In the electricity storage device 10 of the present embodiment, pre-doping of lithium ions on the negative electrode plate 22 of the electrode unit 20 is performed as follows. First, the electrode unit 20, the lithium supply plate 30, and the resistor 40 joined as described above are accommodated between the upper member 51 and the lower member 52. These are sandwiched between the upper member 51 and the lower member 52 so that a part of the positive electrode terminal 60 and the negative electrode terminal 70 are exposed to the outside, and the upper member 51 and the lower member 52 are joined by heat welding or the like. At this time, one side of the exterior member 50 other than the side from which the positive electrode terminal 60 and the negative electrode terminal 70 protrude is left open.

  Then, an electrolytic solution is injected into the exterior member 50 from the opening portion of the exterior member 50. After injecting the electrolytic solution, the opening portion of the exterior member 50 is joined by thermal fusion or the like. The electrode unit 20 and the lithium supply plate 30 are immersed in the injected electrolyte. Thereby, the movement path | route of the lithium ion with respect to the negative electrode plate 22 of the electrode unit 20 from the lithium supply plate 30 is ensured. That is, in the electricity storage device 10, pre-doping of lithium ions starts.

  When lithium ions are released from the lithium supply plate 30 into the electrolytic solution along the stacking direction of the electrode units 20, the lithium supply plate 30 moves to the negative electrode plate 22 of the electrode unit 20 as shown in FIG. In contrast, electrons move. That is, a current flows between the lithium supply plate 30 and the negative electrode plate 22 that are electrically connected to each other according to the potential difference between the lithium supply plate 30 and the negative electrode plate 22.

  At this time, the electricity storage device 10 of the present embodiment has a structure in which the lithium supply plate 30 is electrically connected to the negative electrode terminal 70 via the resistor 40. For this reason, compared with the case where a resistor is not used, electrons pass through the resistor 40, so that the movement of electrons between the lithium supply plate 30 and the negative electrode plate 22 immediately after the start of pre-doping is slow. Become. Thereby, it is suppressed that the electric current which flows between the lithium supply board 30 and the negative electrode plate 22 becomes excessive.

Before the lithium ions in the electrolytic solution are doped into the negative electrode plate 22 by the electrons moved from the lithium supply plate 30 to the negative electrode plate 22, the [Equation 1] between the composition of the electrolytic solution and the lithium ions.
^{2DMC + 2Li + + 2e - →} CH 3 OLi + CH 3 OCOOLi + CH 3 OCOCH 3
[Equation 2]
2EC + 2Li ⁺ + 2e ⁻ → (CH ₂ OCO ₂ Li) ₂ + CH ₂ = CH ₂
A chemical reaction occurs. In addition, the said reaction formula has shown the case where the liquid mixture which mixed ethylene carbonate (Ethylene Carbonate, EC) and dimethyl carbonate (Dimethyl Carbonate, DMC) is used as electrolyte solution.

The chemical reactions shown in the above [Equation 1] and [Equation 2] are single electron reactions. The reaction product (CH ₃ OLi, CH ₃ OCOOLi, (CH ₂ OCOOLi) ₂ ) resulting from the chemical reaction (single-electron reaction) shown in the [Equation 1] and [Equation 2] is shown in FIG. Thus, SEI is formed on the surface of the negative electrode plate 22. This SEI is a layer having lithium ion permeability, and the resistance to the lithium ion permeability increases or decreases depending on the thickness and constituent materials. SEI also functions as a protective layer that suppresses the decomposition reaction of the electrolytic solution.

Here, in the conventional electricity storage device, the negative electrode plate of the electrode unit and the lithium supply plate are electrically connected directly. When pre-doping with such an electricity storage device, before the lithium ion in the electrolytic solution is doped into the negative electrode plate, the above [Equation 1] and [Equation 2] between the composition of the electrolytic solution and the lithium ion. In addition to the chemical reaction shown in the formula,
[Equation 3]
DMC + 2Li ⁺ + 2e ⁻ → Li ₂ CO ₃ + CH ₂ = CH ₂
[Equation 4]
EC + 2Li ⁺ + 2e ⁻ → Li ₂ CO ₃ + CH ₂ = CH ₂
A chemical reaction occurs.

The chemical reactions shown in the above [Equation 3] and [Equation 4] are multi-electron reactions. In the case of a conventional electricity storage device, the reaction product (Li ₂ CO ₃ ) resulting from the chemical reaction (multi-electron reaction) shown in the [Equation 3] and [Equation 4] is mixed in the SEI, resulting in a heterogeneous SEI. Is formed. The occurrence of such a multi-electron reaction is caused by an excessive current flowing between the negative electrode plate and the lithium supply plate.

  In this case, when pre-doping is completed in the electricity storage device, when charging / discharging is repeated, the SEI film thickness is relatively small or the portion made of a substance that easily transmits lithium ions (that is, the portion having low resistance). Lithium ion doping is performed locally. For this reason, in the portion where the lithium ions are locally doped, lithium metal is deposited or a large load is applied, so that the negative electrode plate is easily deteriorated. As a result, the cycle characteristics of the electricity storage device may be deteriorated.

  On the other hand, in the electricity storage device 10 of the present embodiment, the lithium supply plate 30 is electrically connected to the negative electrode terminal 70 via the resistor 40. For this reason, compared with the case where a resistor is not used, electrons pass through the resistor 40, so that the movement of electrons between the lithium supply plate 30 and the negative electrode plate 22 immediately after the start of pre-doping becomes slow. Since the movement of electrons between the lithium supply plate 30 and the negative electrode plate 22 can be sufficiently restricted, it is possible to suppress an excessive current flowing between the lithium supply plate 30 and the negative electrode plate 22. Thereby, in the negative electrode plate 22 of the electrode unit 20, generation of a multi-electron reaction can be suppressed, and SEI having a more homogeneous film on the surface of the negative electrode plate 22 can be formed. In such an electricity storage device 10, after the pre-doping is completed, when charging / discharging is repeated in the electricity storage device 10, the negative electrode plate 22 is unlikely to deteriorate, so that a reduction in cycle characteristics of the electricity storage device 10 can be suppressed. The cycle characteristics refer to the capacitance maintenance rate and the internal resistance change rate of the electricity storage device 10 after repeatedly performing one cycle of charging the electricity storage device 10 to a predetermined voltage and then discharging it.

  If the electric resistance value between the lithium supply plate and the negative electrode terminal is too small, the movement of electrons between the negative electrode plate and the lithium supply plate cannot be sufficiently restricted, and as a result, the negative electrode plate may be easily deteriorated. is there. On the other hand, in this embodiment, the deterioration of the negative electrode plate is suppressed by setting the electric resistance value of the resistor 40 to 50Ω or more. As a result, the deterioration of the cycle characteristics of the electricity storage device 10 is suppressed. Yes.

  On the other hand, if the electrical resistance value between the lithium supply plate and the negative electrode terminal is too large, the movement of electrons between the negative electrode plate and the lithium supply plate is excessively limited, and the doping of lithium ions into the negative electrode plate is completed. It takes a long time to complete. In this case, the productivity of the electricity storage device may be reduced. As a result, the doping of lithium ions becomes insufficient, and the initial characteristics of the electricity storage device may be degraded.

  On the other hand, in this embodiment, by setting the electric resistance value of the resistor 40 to 500Ω or less, it is possible to suppress a long time until the doping of lithium ions to the negative electrode plate is completed, and The reduction in productivity of the device 10 is suppressed.

  Further, in this embodiment, by setting the electric resistance value of the resistor 40 to 500Ω or less, the lithium ion can be sufficiently doped, so that the electricity storage device 10 having more excellent initial characteristics can be obtained. . The initial characteristics of the electricity storage device 10 refer to the capacitance and internal resistance value in the initial state immediately after one cycle of charging the electricity storage device 10 to a predetermined voltage and then discharging it.

  Moreover, since the resistor 40 of this embodiment can be attached comparatively easily only by joining with the lithium supply plate 30 and the negative electrode terminal 70 by welding or the like, while suppressing an increase in production cost and production process. , The above-mentioned actions and effects can be obtained. In the present embodiment, the electric resistance value can be changed relatively easily by simply replacing the resistor 40.

  Further, in the present embodiment, the joint portion between the negative electrode terminal 70 and the lead portion 223 of the negative electrode plate 22 and the joint portion between the negative electrode terminal 70 and the lead portion 312 of the lithium supply plate 30 are different portions. For this reason, the conduction path length between the negative electrode terminal 70 and the lithium supply plate 30 and the conduction path length between the negative electrode terminal 70 and each negative electrode plate 22 are more likely to be uniform. As a result, the electric resistance value between the negative electrode terminal 70 and the lithium supply plate 30 and the electric resistance value between the negative electrode terminal 70 and each negative electrode plate 22 are more easily equalized. 22 can be uniformly doped with lithium ions.

  Specifications such as the external shape (size and thickness), capacity, and output voltage of the electricity storage device 10 described above are appropriately set according to the application. Further, the output voltage can be adjusted by electrically connecting a plurality of power storage devices 10 in series, and the power storage capacity can be adjusted by electrically connecting the plurality of power storage devices 10 in parallel.

  An example of the power storage module 1 including a plurality of power storage devices 10 will be described with reference to FIGS. 7 and 8. FIG. 7 is a perspective view showing the power storage module according to the embodiment of the present invention, and FIG. 8 is an equivalent circuit diagram of the power storage module shown in FIG.

  As shown in FIGS. 7 and 8, the power storage module 1 according to the present embodiment includes a plurality (ten in this example) of power storage devices 10 stacked on each other. These power storage devices 10 are stacked such that the positive electrode terminal 60 of the lower power storage device 10 faces the negative electrode terminal 70 of the upper power storage device 10. Support members 2 made of an electrically insulating material are interposed between the storage devices 10 adjacent to each other, and bolts 3 are inserted into through holes formed at the four corners of the support member 2 and fastened. Thus, the plurality of power storage devices 10 are fixed.

  Further, the positive terminal 60 of the lower power storage device 10 and the negative terminal 70 of the upper power storage device 10 are directly connected using the connection member 4. The positive terminal 60 of the uppermost power storage device 10 among the ten power storage devices 10 constitutes the positive input / output terminal 5 of the power storage module 1. On the other hand, the negative electrode terminal 70 of the lowest power storage device 10 among the ten power storage devices 10 constitutes the negative electrode input / output terminal 6 of the power storage module 1.

  Also in such an electricity storage module 1, in each electricity storage device 10, the lithium supply plate 30 is electrically connected to the negative electrode terminal 70 via the resistor 40, and the electrical resistance value of the resistor is 50Ω to 500Ω. By being, it can suppress the fall of the cycle characteristic of the said electrical storage module 1. FIG.

  The embodiment described above is described for facilitating the understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  For example, in the present embodiment, the positive electrode terminal 60 and the negative electrode terminal 70 extend outward from different ends of the exterior member 50, but are not particularly limited to the above, and the positive electrode terminal and the negative electrode terminal are external You may extend toward the exterior from the same edge part of a member.

  In the present embodiment, the exterior member 50 is configured by sealing the outer periphery of the upper member 51 and the outer periphery of the lower member 52 over the entire periphery of the exterior member 50. The structure is not particularly limited to the above. For example, one rectangular exterior member is prepared, and one rectangular exterior member is folded in half from the central portion of the long side so that one end and the other end face each other, and then folded in two. Out of the four end portions of the exterior member, the positive electrode terminal and the negative electrode terminal are arranged at the end portion other than the folded portion, and the three end portions other than the end portion including the folded portion are sealed to seal the exterior member. It may be configured.

  The effects of the present invention were confirmed by examples and comparative examples that further embody the present invention. The following examples and comparative examples are for confirming the effect of suppressing the deterioration of the cycle characteristics of the electricity storage device in the above-described embodiment.

<Example 1>
In Example 1, a lithium ion capacitor was produced. Carboxymethylcellulose sodium salt was dissolved in water to obtain a 3 wt% aqueous solution of sodium carboxymethylcellulose salt. Hard carbon, acetylene black, styrene-butadiene rubber, and water were mixed in this aqueous solution. In this case, the weight ratio of each material was set to a ratio of hard carbon: acetylene black: styrene-butadiene rubber: carboxymethyl cellulose sodium salt = 90: 4: 3: 3. From the above, a slurry used for the negative electrode plate was obtained. Next, the prepared slurry was applied to both surfaces of a 15 μm-thick copper etching foil in which through-holes having a diameter of 110 μm were formed at equal intervals of 175 μm so that the basis weight after drying was 60 g / m ² . . The coated slurry was dried, and a negative electrode active material layer having a thickness of 30 μm was formed on both surfaces of a copper expanded metal. Thus, a negative electrode plate intermediate body having a thickness of 75 μm was obtained. Next, the negative electrode plate intermediate was cut to form a positive electrode current collector having a main body portion and a lead portion. In addition, the negative electrode active material layer was not formed on both surfaces of the lead portion, and the copper expanded metal was exposed. The dimensions of the main body were 26 mm wide and 40 mm long. The dimensions of the lead part were 4 mm wide and 10 mm long. Six negative electrode plates as described above were prepared.

Carboxymethylcellulose sodium salt was dissolved in water to obtain a 3 wt% aqueous solution of sodium carboxymethylcellulose salt. Activated carbon, acetylene black, styrene-butadiene rubber, and water were mixed with this aqueous solution. In this case, the weight ratio of each material was a ratio of activated carbon: acetylene black: styrene-butadiene rubber: carboxymethyl cellulose sodium salt = 84: 6: 6: 4. The slurry used for a positive electrode plate was obtained by the above. Next, a slurry prepared so that the weight per unit area after drying is 60 g / cm ^{2 on} both surfaces of a 30 μm-thick aluminum etching foil in which a plurality of through-holes having a diameter of 2 to 3 μm are formed at unequal intervals, respectively. Coated. The coated slurry was dried, and a positive electrode active material layer having a thickness of 60 μm was formed on both surfaces of an aluminum expanded metal. Thus, a positive electrode plate intermediate having a thickness of 150 μm was obtained. Next, the positive electrode plate intermediate was cut to form a positive electrode current collector having a main body portion and a lead portion. The positive electrode active material layer was not formed on both surfaces of the lead part, and the aluminum expanded metal was exposed. The dimensions of the main body were 26 mm wide and 40 mm long. The dimensions of the lead part were 4 mm wide and 10 mm long. Five positive electrode plates as described above were prepared.

  Twelve separators made of cellulose having a thickness of 25 μm were prepared. The separator was 30 mm wide and 44 mm long.

  A separator, a negative electrode plate, a separator, a positive electrode plate, and a separator were laminated in this order to form an electrode unit composed of 12 separators, 6 negative plates, and 5 positive plates. The negative electrode plate was arranged on the uppermost stage of the electrode unit.

  A copper plate having a thickness of 30 μm was cut to form a lithium electrode current collector having a main body portion and a lead portion. The dimensions of the main body were 26 mm wide and 40 mm long. The dimensions of the lead part were 4 mm wide and 10 mm long. Next, a metal lithium foil was bonded to one main surface of the main body. The dimensions of the metal lithium foil were 26 mm wide and 40 mm long. Thus, a lithium supply plate was obtained.

  A resistor body having a resistor main body and two copper lead portions extending from both ends of the resistor main body was prepared. Carbon resistance was used as the resistance main body. The electrical resistance value of the resistor was 50Ω.

  A nickel-plated copper negative electrode terminal having a width of 5 mm, a length of 40 m, and a thickness of 0.1 mm was prepared. Moreover, the aluminum positive electrode terminal of width 5mm, length 40mm, and thickness 0.1mm was prepared.

  One lead portion of the resistor was joined to the lead portion of the lithium supply plate by resistance welding. Thereafter, the entire lead portion of the lithium supply plate was wound with Kapton tape. The electrode unit and the lithium supply plate are stacked facing each other so that the lithium metal foil is positioned on the lowermost side of the electrode unit, and the outer periphery of the laminate of the electrode unit and the lithium supply plate is separated by a separator having a width of 70 mm and a length of 44 mm. The both ends of the separator were fixed with kabuton tape. The lead part of each positive electrode plate and the positive electrode terminal were arranged to overlap each other, and these were joined together by ultrasonic welding. The lead part of each negative electrode plate and the negative electrode terminal were arranged to overlap each other, and these were joined together by resistance welding. The other lead portion of the resistor was joined to the negative electrode terminal by resistance welding at a portion different from the joint portion between the lead portion of the negative electrode plate and the negative electrode terminal.

  Two exterior members in which polypropylene, aluminum, and polypropylene were sequentially laminated were prepared. The dimensions of the exterior member were 80 mm width and 60 mm length. The above-mentioned electrode unit, lithium supply plate, and resistor are sandwiched between two exterior members, and the negative electrode terminal and a part of the positive electrode terminal are exposed from the two exterior members. Three sides of the periphery were joined by heat welding.

  An electrolyte solution in which 1.2 mol / L LiPF6 was dissolved in a mixed solvent in which the volume ratio of each material was mixed at a ratio of ethylene carbonate: propylene carbonate: diethyl carbonate = 3: 1: 4 was prepared. 2 L of the electrolyte was injected from the opening portion of the exterior member that was not joined. The opening part of the exterior member was joined by heat welding. Thus, an electricity storage device was obtained. The electricity storage device was left for 9 days and pre-doped. The following tests were conducted using the above test samples.

≪Performance evaluation test≫
The obtained test sample was charged with a constant current of 0.2 A for 30 minutes until the output voltage of the test sample reached 3.8 V, and further charged with a constant voltage of 3.8 V for 30 minutes. Thereafter, the test sample was discharged for 6 minutes at a constant current of 0.2 A until the output voltage of the test sample reached 2.2V. The electrostatic capacity after completion of the discharge of the test sample was measured by a 580 type charge / discharge system manufactured by Toyo Technica. Moreover, the electrostatic capacity was calculated from the following [Equation 5] based on the measurement result of the discharge test of the discharge system.
[Equation 5]
Capacitance (F) = discharge current (A) × discharge time (S) / (voltage immediately before discharge (V) −voltage immediately after discharge (V))
The capacitance at this time was set as the capacitance of the initial characteristics of the test sample. Moreover, the internal resistance value after completion of the discharge of the test sample was measured by the IR drop method based on the result of the discharge test. The internal resistance of the test sample at this time was defined as the internal resistance value of the initial characteristics of the test sample.

  The test sample is charged for 36 seconds at a constant current of 2A until the output voltage of the test sample reaches 3.8V, and then the output voltage of the test sample reaches 2.2V at a constant current of 2A. The charge / discharge cycle of discharging for 36 seconds was repeated 10,000 times. After the charge / discharge cycle is completed, the test sample is charged with a constant current of 0.2 A for 30 minutes until the output voltage of the test sample becomes 3.8 V, and further, a constant voltage charge of 3.8 V is performed for 30 minutes. went. Thereafter, the battery was discharged for 6 minutes at a constant current of 0.2 A until the output voltage of the test sample reached 2.2V. The capacitance of the test sample after the completion of discharge was measured by the same method as the above measuring apparatus and measuring method. The capacitance at this time was taken as the capacitance after the performance evaluation test of the test sample. Moreover, the internal resistance value after completion of the discharge of the test sample was measured by the same method as the above measurement method. The internal resistance value at this time was defined as the internal resistance value after the performance evaluation test of the test sample. The ratio of the capacitance after the performance evaluation test to the capacitance of the initial characteristics was calculated as the capacitance retention rate. Further, the ratio of the internal resistance value after the performance evaluation test to the internal resistance value of the initial characteristics was calculated as the internal resistance change rate.

  When the capacitance retention rate was 95% or more and the internal resistance change rate was 120% or less, it was determined that “◯ (good)” was excellent in the effect of suppressing deterioration in cycle characteristics. When the capacitance maintenance rate is 95% or more and the internal resistance change rate is 120% or less, but the initial characteristic capacitance is 38F or less, or the initial characteristic internal resistance value is 163 mΩ or more, It was determined that the performance was inferior “Δ (impossible)”. When the capacitance retention rate was less than 95% or the internal resistance change rate was greater than 120%, “x (defect)” was indicated that the effect of suppressing deterioration in cycle characteristics was inferior. The results are shown in Table 1.

<Example 2>
A test sample was produced in the same manner as in Example 1 except that the electric resistance value of the resistor was 200Ω. A performance evaluation test was performed on this test sample. The results are shown in Table 1.

<Example 3>
A test sample was produced in the same manner as in Example 1 except that the resistance value of the resistor was 500Ω. A performance evaluation test was performed on this test sample. The results are shown in Table 1.

<Comparative Example 1>
A test sample was used in the same manner as in Example 1 except that the lead part of the negative electrode plate, the lead part of the lithium supply plate, and the negative electrode terminal were stacked and joined together by resistance welding without using a resistor. Was made. A performance evaluation test was performed on this test sample. The results are shown in Table 1.

<Comparative example 2>
A test sample was produced in the same manner as in Example 1 except that the electrical resistance value of the resistor was 10Ω. A performance evaluation test was performed on this test sample. The results are shown in Table 1.

<Comparative Example 3>
A test sample was produced in the same manner as in Example 1 except that the resistance value of the resistor was 1000Ω. A performance evaluation test was performed on this test sample. The results are shown in Table 1.

  As shown in Table 1, in Examples 1 to 3, it was found that “◯” indicates that the effect of suppressing the deterioration of the cycle characteristics of the electricity storage device is excellent. On the other hand, for Comparative Examples 1 and 2, it was found that “x” indicates that the effect of suppressing the deterioration of the cycle characteristics of the electricity storage device is inferior to that of Examples 1 to 3 and Comparative Example 3. Regarding Comparative Example 3, although there is an effect of suppressing the deterioration of the cycle characteristics of the electricity storage device, the capacitance of the initial characteristics is 38 F or less and the internal resistance value of the initial characteristics is 163 mΩ or more. “△” indicates that the performance of the electricity storage device is inferior to that.

  As described above, in the electricity storage device, the negative electrode terminal and the negative electrode plate are electrically connected, and the negative electrode terminal and the lithium supply plate are electrically connected via the resistor, and the electric resistance value of the resistor It was confirmed that Example 1 to Example 3 in which is 50Ω or more has an effect of suppressing a decrease in cycle characteristics of the electricity storage device. This is because if there is no resistor or the electrical resistance value of the resistor is less than 50Ω, an excessive current flows between the lithium supply plate and the negative electrode plate immediately after the start of pre-doping, and the surface of the negative electrode plate Homogeneous SEI is not formed, and the negative electrode plate is deteriorated in the subsequent charge / discharge cycle. On the other hand, if the electrical resistance value of the resistor is 50Ω or more, immediately after the start of pre-doping, between the lithium supply plate and the negative electrode plate Since it is possible to suppress excessive current from flowing to the surface of the negative electrode plate, relatively uniform SEI can be formed on the surface of the negative electrode plate, and as a result, deterioration of the negative electrode plate can be suppressed in the subsequent charge / discharge cycle. Conceivable.

  Moreover, it was also confirmed that Example 1-Example 3 whose electrical resistance value of said resistor is 500 ohms or less has the inhibitory effect of the fall of the initial characteristic of an electrical storage device collectively. This is because, when the electrical resistance value of the resistor is larger than 500Ω, sufficient current does not flow between the lithium supply plate and the negative electrode plate immediately after the start of pre-doping, whereas the negative electrode plate is insufficiently doped with lithium ions. If the electrical resistance value of the resistor is 500Ω or less, a sufficient current flows between the lithium supply plate and the negative electrode plate immediately after the start of pre-doping, and the lithium ion doping to the negative electrode plate is sufficient. It is done.

  As described above, Examples 1 to 3 in which the electrical resistance value of the resistor is 50Ω to 500Ω have the effect of suppressing the deterioration of the cycle characteristics of the power storage device and the effect of suppressing the decrease of the initial characteristics of the power storage device. It was confirmed.

DESCRIPTION OF SYMBOLS 1 ... Power storage module 2 ... Support member 3 ... Bolt 4 ... Connection member 5 ... Positive electrode input terminal 6 ... Negative electrode input terminal 10 ... Power storage device 20 ... Electrode unit 21 ... Positive electrode plate 211 ... Positive electrode collector
212 ... Main unit
212a ... through hole
213 ... Lead part
213a ... tip
214 ... Positive electrode active material layer
214a ... Outer edge portion 22 ... Negative electrode plate 221 ... Negative electrode current collector
222 ... Body part
222a ... through hole
223 ... Lead part
223a ... tip 224 ... negative electrode active material layer
224a ... Outer edge 23 ... Separator 30 ... Lithium supply plate 31 ... Lithium electrode current collector 311 ... Main body
311a ... Through hole 312 ... Lead part
312a ... tip 32 ... lithium supply source 40 ... resistor 41 ... resistor body 42, 43 ... lead 42a, 43a ... tip 50 ... exterior member 50a ... metal foil 50b ... first resin film 50c ... second resin film 51 ... Upper member 511 ... Recess 52 ... Lower member 521 ... Recess 53 ... Sealed portion 60 ... Positive terminal 61,62 ... End 70 ... Negative terminal 71,72 ... End

Claims (3)

An electrode unit including a positive electrode plate and a negative electrode plate;
A lithium supply plate for supplying lithium ions to the negative electrode plate;
A positive electrode terminal electrically connected to the positive electrode plate;
A negative electrode terminal electrically connected to the negative electrode plate and electrically connected to the lithium supply plate via a resistor;
The electrical storage device in which the electrical resistance value of the resistor is 50Ω to 500Ω. The electricity storage device according to claim 1,
The negative electrode plate has a first current collector,
The first current collector is:
A first main body holding a layer containing a negative electrode active material;
A first lead portion extending from the first main body portion,
The lithium supply plate further includes a second current collector and a lithium supply source,
The second current collector is
A second main body for holding the lithium supply source;
A second lead portion extending from the second main body portion,
The resistor is
A resistance body,
First and second connection portions for electrically connecting the resistance main body portion to the outside, and
The first lead portion is joined to the negative terminal,
The second lead portion is joined to the first connection portion,
The power storage device in which the second connection portion is joined to the negative electrode terminal at a portion different from a joint portion between the first lead portion and the negative electrode terminal. A power storage module comprising two or more power storage devices according to claim 1 or 2,
Each power storage device is a power storage module connected in series or in parallel.

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