JP2009129917A - Power storage device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power storage device using an electrolyte containing lithium salt, which can prevent lithium metal precipitation in each of negative electrodes, thereby unfailingly preventing short-circuit between each of positive electrodes and each of the negative electrodes from being caused by lithium metal precipitation. <P>SOLUTION: The power storage device has a configuration in which the planar positive electrode plates 10 each having an positive electrode 14 formed on the surface of a current corrector 13 and planar negative electrode plates 12 each having a negative electrode 16 made of a substance capable of absorbing and discharging lithium ions on the surface of a current corrector 15 are stacked via a separator 11 and an electrolyte containing lithium salt is filled therebetween, wherein the negative electrode 16 is doped with lithium in advance and formed to have an outer dimension larger than that of the positive electrode 14, and the plurality of positive electrodes 14 are disposed so that some of the outer peripheral edges are not coincident with the outer peripheral edges of the positive electrodes 14 of an adjacent layer in a stacking direction and the outer peripheral edges are positioned inside the outer peripheral edges of the negative electrodes 16. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electricity storage device such as a lithium ion capacitor or a lithium ion secondary battery in which an electrolyte containing a lithium salt is injected between a plurality of positive and negative electrode plates arranged opposite to each other with a separator interposed therebetween. Is.

  In recent years, lithium-ion capacitors, a type of electricity storage device that uses an electrolyte containing lithium salt, have extremely large energy capacity and rapid charge / discharge despite being smaller and lighter than conventional batteries. Therefore, it is being used in a wide range of fields such as a load leveling device for wind power generation, a voltage sag countermeasure device, a backup power supply device in a hybrid electric vehicle, a fuel cell vehicle, and the like.

On the other hand, in this type of lithium ion capacitor, for example, as can be seen in Patent Document 1 below, a lithium ion capacitor that stores electricity using a conventional electric double layer function by previously doping lithium into the negative electrode In addition to increasing the voltage, the energy density has been increased to enable further reduction in size and weight.
Japanese Patent No. 3485935

  By the way, such a lithium ion capacitor generally includes a plurality of plate-like positive electrode plates in which positive electrodes are formed on both sides of a current collector, and a negative electrode made of a material capable of inserting and extracting lithium ions on both sides of the current collector. A plurality of flat plate-like negative electrode plates formed with a separator are alternately laminated with a separator interposed therebetween, and a load in the compression direction is applied between both end portions of the obtained laminated body to integrate them. And an electrolyte containing a lithium salt is injected.

  At this time, if the positive electrode and the negative electrode are formed to have the same size and shape, the separator is sandwiched between the outer peripheral edge of the positive electrode and the outer peripheral edge of the negative electrode. Due to the burr and distortion of the part, stress due to the compressive force concentrates on the outer peripheral edge that is convex on the separator side, and as a result, the outer peripheral edge penetrates the separator and contacts the other, thereby causing a short circuit between them. May occur. Such an adverse effect may occur as the assembly accuracy increases and the outer peripheral edges of the positive electrode and the negative electrode exactly coincide with the stacking direction, or as the separator becomes thinner as the device is downsized. Becomes higher.

  For this reason, a measure to alleviate the stress concentration can be considered by making one of the positive and negative electrodes in direct contact with the separator smaller in size than the other. For example, as shown in FIG. When laminating a rectangular plate-like positive electrode plate 3 in which a positive electrode 2 is formed on both sides of 1 and a square plate-like negative electrode plate 6 in which a negative electrode 5 is formed on both sides of a current collector 4 with a separator 7 interposed therebetween When the external dimensions of the negative electrode 5 are made smaller than the external dimensions of the positive electrode 2, current is excessively concentrated on the outer periphery of the negative electrode 5, as shown by a dotted line in the figure. As a result, the negative electrode 5 is doped with lithium in advance. In such a case, there arises a problem that lithium metal easily deposits.

  Therefore, as shown in FIG. 7, if the outer dimensions of the negative electrode 5 are made larger than the outer dimensions of the positive electrode 2, it is possible to prevent the occurrence of excessive current concentration at the outer peripheral edge of the negative electrode 5 described above.

  However, in the above configuration, as shown in FIG. 8, when a large number of positive plates 3 and negative plates 6 are stacked, the outer peripheral edges of all the positive electrodes 2 are at the same position P in the stacking direction. For this reason, stress concentration due to the load in the compression direction occurs on the outer peripheral edge of the positive electrode 2, and as a result, when the thickness of the negative electrode plate 6 is thin, a concave bend occurs in the portion facing the outer peripheral edge of the positive electrode 2. Concentration occurs, causing a problem that lithium metal is deposited in the same manner.

  The present invention was made in view of such circumstances, can prevent the deposition of lithium metal in the negative electrode, thus reliably preventing a short circuit between the positive electrode plate and the negative electrode plate due to the lithium metal deposition, It is an object of the present invention to provide an electricity storage device using an electrolytic solution containing a lithium salt that enables further thinning of the constituent members.

  In order to solve the above-mentioned problems, the invention according to claim 1 is capable of inserting and extracting lithium ions on the surface of the current collector and a plate-like positive electrode plate having a positive electrode formed on the surface of the current collector. In a power storage device in which a plurality of flat plate-like negative electrode plates each having a negative electrode made of a material are stacked with a separator interposed therebetween, and an electrolyte containing a lithium salt is injected therebetween, the negative electrode Is pre-doped with lithium and has an outer dimension larger than that of the positive electrode, and the positive electrodes of the plurality of stacked positive plates are such that at least a part of the outer periphery of the positive electrode of the adjacent layer The outer peripheral edge of the negative electrode is not aligned with the stacking direction, and the outer peripheral edge is located inside the outer peripheral edge of the negative electrode.

  The invention described in claim 2 is arranged such that in the invention described in claim 1, the outer peripheral edge of the positive electrode does not coincide with the outer peripheral edge of the positive electrode of the layer adjacent to the entire circumference in the stacking direction. It is characterized by that.

  Here, the fact that the outer peripheral edge of the positive electrode does not coincide with the outer peripheral edge of the positive electrode of the layer adjacent to the entire circumference means that the outer peripheral edges of the two do not coincide on the same line in the stacking direction. Are not included in the coincidence.

  Furthermore, the invention described in claim 3 is the invention described in claim 1 or 2, wherein the plurality of positive plates are formed in the same shape, and the plurality of negative plates are formed in the same shape. It is characterized by being.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the power storage device is a lithium ion capacitor.

  In the invention according to any one of claims 1 to 4, the outer dimension of the negative electrode is formed larger than the outer dimension of the positive electrode, and the outer peripheral edge of the positive electrode is disposed inside the outer peripheral edge of the negative electrode. Therefore, it is possible to prevent current from being excessively concentrated on the outer peripheral edge of the negative electrode and depositing lithium metal on the portion.

  In addition, when laminating a plurality of positive electrode plates, at least a part of the outer peripheral edge of the positive electrode in each positive electrode plate is arranged so as not to coincide with the outer peripheral edge of the positive electrode of the layer adjacent thereto. In addition, the outer peripheral edge of all the positive electrodes does not become the same position in the stacking direction, and therefore, stress concentration does not occur on the outer peripheral edge of the positive electrode due to the compressive load acting in the stacking direction.

  For this reason, local concave bending due to the stress concentration does not occur in the negative electrode plate facing the vicinity of the outer peripheral edge of the positive electrode plate. Precipitation of metal can also be prevented. As a result, precipitation of lithium metal in the negative electrode can be prevented, and therefore, a short circuit between the positive electrode plate and the negative electrode plate due to the lithium metal precipitation can be reliably prevented. Such a structural member can be made thinner.

  Here, in order to reliably avoid stress concentration on the outer peripheral edge of the positive electrode due to the compressive load, the positive electrode of the layer whose outer peripheral edge is adjacent to the entire periphery as in the invention of claim 2 is used. It is preferable to arrange so as not to coincide with the outer peripheral edge of the film in the stacking direction.

  Further, in the invention described in claim 1 or 2, it is possible to cope by changing the external dimensions of the positive electrodes in the plurality of positive electrodes located above and below in the stacking direction. If the plurality of positive plates are formed in the same shape and the plurality of negative plates are formed in the same shape as in the invention, the positive plates arranged between the negative plates are adjacent to each other in the stacking direction. It is possible to easily cope with the problem by arranging the layer positive electrode plate somewhat shifted in the direction perpendicular to the stacking direction. In addition, since it is only necessary to prepare a positive electrode plate and a negative electrode plate having a single shape as the entire apparatus, the manufacturing cost is not increased, and stable power storage performance can be ensured.

  Therefore, the invention described in claims 1 to 3 is particularly effective when applied to a lithium ion capacitor that is required to have a higher voltage and a higher energy density, as in the invention described in claim 4. Play.

1 to 5 show an embodiment in which an electricity storage device according to the present invention is applied to a lithium ion capacitor.
The lithium ion capacitor includes a positive electrode plate 10, a separator 11, and a negative electrode plate 12 that form a set of power storage units, and a plurality of the above power storage units are stacked, and between the positive electrode plate 10, the separator 11, and the negative electrode plate 12. The electrolyte is roughly configured by injecting an electrolyte containing a lithium salt.

  Here, in the positive electrode plate 10, positive electrodes 14 made of a carbon material were formed on both surfaces of a current collector 13 made of a metal foil having oxidation resistance and not chemically eluting, such as nickel foil or aluminum foil. A connecting tongue 13 a is integrally formed on one side of the current collector 13.

  More specifically, this positive electrode plate 10 has activated carbon YP-17 (manufactured by Kuraray Chemical Co., Ltd.), acetylene black HS-100 (electrochemical) on both surfaces of the current collector 13 having a thickness of 25 μm to 35 μm. Manufactured by Kogyo Co., Ltd.), an aqueous dice version of PTFE (polytetrafluoroethylene) (Mitsui DuPont Fluorochemical 30J), and a 2 wt% aqueous solution of CMC (Serogen 4H, 1st Pharmaceutical Co., Ltd.) in a weight ratio of 88: 8: 2. : Mixing so as to be 2, and adding distilled water to knead into a paste to prepare a positive electrode mixture slurry, rolling the obtained positive electrode mixture slurry, the thickness of 70μm ~ 90μm After forming the positive electrode 14, it was created by punching into the shape shown in FIG. 1 using a mold. The ratio of the aqueous PTFE (Mitsui DuPont Fluorochemical 30J) and CMC (Serogen 4H, Daiichi Pharmaceutical Co., Ltd.) is a solid content ratio. Thereby, this positive electrode plate 10 and the positive electrode 14 on the surface thereof are formed in a square shape (square in the drawing) of (50 mm to 150 mm) × (50 mm to 150 mm).

  Further, the negative electrode plate 12 is made of a non-graphitizable carbon material (PIC manufactured by Kureha Chemical Co., Ltd.), which is a negative electrode material, and polyvinylidene fluoride resin (KF # 1100 manufactured by Kureha Chemical Co., Ltd.) at a weight ratio of 95: 5. After mixing, adding N-methyl-2-pyrrolidinone as a solvent and kneading into a paste, it was applied to both sides of a copper foil having a thickness of 14 μm, dried and rolled to form the negative electrode 16, 1 is formed by punching into the shape shown in FIG. 1, and a connecting tongue 15 a is integrally formed on one side of the current collector 15.

  Incidentally, the thickness dimension of the current collector 15 in the negative electrode plate 12 is 12 to 16 μm, and the negative electrode 16 is formed to have a thickness dimension of 36 to 40 μm. Further, the negative electrode 16 in the negative electrode plate 12 is a (50 mm to 150 mm) × (50 mm to 150 mm) square (rectangular in the drawing) and is formed to have a size larger than that of the positive electrode 14. Note that the current collector 15 is formed such that the dimension between the pair of opposing sides is larger than the formation dimension of the negative electrode 16, whereby the current collector 15 has a pair of opposing sides and the negative electrode 16. An exposed portion 15b of the current collector is formed.

  Further, the separator 11 is made of a sheet material having liquid permeability and non-electron conductivity made of a synthetic resin such as polyethylene or polypropylene, glass fiber, or the like, and is a square having the same outer dimensions as the current collector 15 of the negative electrode plate 12. (Rectangular in the figure).

  In the lithium ion capacitor, as shown in FIG. 5, a plurality of positive electrode plates 10 having the same shape and a plurality of negative electrode plates 12 having the same shape are alternately stacked with the separator 11 interposed therebetween. As shown in FIG. 1, external terminals 17 and 18 are welded to the connecting tongues 13a and 15a formed on the current collectors 13 and 15 of the negative electrode plate 12, respectively, and both end portions of the obtained laminate are obtained. It is integrated by applying a load in the compression direction between them, and further housed in an exterior made of a laminate film, etc., and after an electrolyte containing a lithium salt such as LiI, LiClO4, LiAsF6 is injected therein, The interior is configured by being evacuated and sealed. At this time, the negative electrode 15 is pre-doped with diffused lithium ions.

  Here, in the lithium ion capacitor, the plurality of positive electrode plates 10 are arranged such that at least a part of the outer peripheral edge of the positive electrode 14 does not coincide with the outer peripheral edge of the positive electrode 14 of the positive electrode plate 10 positioned immediately below in the stacking direction. They are arranged in a state where they are sequentially shifted in a direction perpendicular to the stacking direction. Even in this case, all the positive plates 10 are arranged such that the outer peripheral edges of the respective positive electrodes 14 are located on the inner side of the outer peripheral edge of the negative electrode 16 of the negative electrode plate 12.

  That is, as shown in FIG. 2, the positive electrode plate 10b positioned immediately below the positive electrode plate 10a positioned at the uppermost stage in the stacking direction is disposed at a position slightly shifted to the right in the figure. The positive electrode plate 10c positioned immediately below the positive electrode plate 10b is disposed at a position slightly shifted downward in the figure relative to the positive electrode plate 10b. The positive electrode plate 10d positioned directly below the positive electrode plate 10c is The positive electrode plate 10 located below the positive electrode plate 10d is also arranged at a position slightly shifted in the direction perpendicular to the stacking direction in the same manner as described above. Yes.

  Moreover, in the example of arrangement | positioning of the other positive electrode plate 10 shown in FIG. 4, as for the positive electrode plate 10 located immediately under the positive electrode plate 10, the positive electrode 14 of the positive electrode plate 10 immediately above and all four corner | angular parts do not correspond. In other words, the outer peripheral edge is arranged so as not to coincide with the outer peripheral edge of the positive electrode 14 positioned immediately above the entire periphery in the stacking direction.

  According to the lithium ion capacitor having the above configuration, the outer dimensions of the negative electrode 16 are formed larger than the outer dimensions of the positive electrode 14, and the positive electrode 10 is positioned so that the outer peripheral edge of the positive electrode 14 is inside the outer peripheral edge of the negative electrode 16. Therefore, it is possible to prevent current from being excessively concentrated on the outer peripheral edge of the negative electrode 16 and depositing lithium metal on the portion.

  In addition to this, when laminating the plurality of positive plates 10, at least a part (FIG. 2) or all (FIG. 4) of the outer peripheral edge of the positive electrode 14 in each positive plate 10 is positioned immediately below the positive plate 10. 3 and FIG. 5, the positive electrode 14 immediately below the position P of the outer peripheral edge of any positive electrode 14 is arranged. The outer peripheral edge of the sheet is shifted in a direction perpendicular to the stacking direction.

  For this reason, stress concentration does not occur on the outer peripheral edge of the positive electrode 14 due to the compressive load acting in the stacking direction. Therefore, the portion of the negative electrode 16 facing the outer peripheral edge of the positive electrode 14 has a local concave shape due to the stress concentration. Since bending does not occur, it is possible to prevent lithium metal from being deposited on the surface of the negative electrode 16 due to current concentration caused by the bending.

  Here, in order to reliably avoid stress concentration on the outer peripheral edge of the positive electrode due to the compressive load, as in the invention according to claim 2, the outer peripheral edge of the positive electrode is positioned directly below the entire periphery. It is preferable to arrange the positive electrode so as not to coincide with the outer peripheral edge of the positive electrode.

  Therefore, according to the lithium ion capacitor, it is possible to prevent lithium metal from being deposited on the negative electrode 16, and thus it is possible to reliably prevent a short circuit between the positive electrode plate 10 and the negative electrode plate 12 due to the lithium metal deposition. Therefore, it is possible to further reduce the thickness of the constituent members such as the positive electrode plate 10, the negative electrode plate 12, and the separator 11.

  Further, since the plurality of positive electrode plates 10 having the same shape as each other and the plurality of negative electrode plates 12 having the same shape as each other are used, the positive electrode plates 10 arranged between the negative electrode plates 12 are The positive electrode plate 10 positioned immediately below the stacking direction can be easily accommodated by being shifted somewhat in the direction orthogonal to the stacking direction.

  In addition, since the positive electrode plate 10, the separator 11, and the negative electrode plate 12 having one type of shape are prepared as the entire apparatus, the manufacturing cost is not increased, and stable power storage performance can be ensured.

  In the above embodiment, the case where the electricity storage device according to the present invention is applied only to a lithium ion capacitor has been described. However, the present invention is not limited to this, and a plurality of positive electrode plates arranged opposite to each other with a separator interposed therebetween. The present invention can be similarly applied to an electricity storage device such as a lithium ion secondary battery in which an electrolyte containing a lithium salt is injected between the electrode and the negative electrode plate.

It is a top view which shows the shape of the positive electrode plate, separator, and negative electrode plate in one Embodiment of this invention. It is a top view which shows the positional relationship of the lamination direction of the some positive electrode plate in the said embodiment. It is a front view which decomposes | disassembles and shows the lamination | stacking state of the positive electrode plate of FIG. 1, a separator, and a negative electrode plate. It is a perspective view which shows the other example of the positional relationship in the lamination direction of the positive electrode plate of FIG. It is a front view which shows the laminated body of the positive electrode plate of FIG. 1, a separator, and a negative electrode plate. It is a front view which shows the state at the time of forming a negative electrode smaller than a positive electrode in a lithium ion capacitor. It is a front view which shows the state at the time of forming a negative electrode larger than a positive electrode in a lithium ion capacitor. It is a front view which shows the lithium ion capacitor of FIG.

Explanation of symbols

10, 10a, 10b, 10c, 10d Positive electrode plate 11 Separator 12 Negative electrode plate 13, 15 Conductor 14 Positive electrode 16 Negative electrode

Claims (4)

A plate-like positive electrode plate in which a positive electrode is formed on the surface of the current collector, and a plate-like negative electrode plate in which a negative electrode made of a material capable of occluding and releasing lithium ions is formed on the surface of the current collector. In an electricity storage device in which a plurality of layers are stacked with an electrolyte solution containing a lithium salt interposed therebetween,
The negative electrode is previously doped with lithium and has an outer dimension larger than that of the positive electrode,
The positive electrodes of the plurality of stacked positive electrode plates have at least a part of the outer peripheral edge thereof not aligned with the outer peripheral edge of the positive electrode of the adjacent layer in the stacking direction, and the outer peripheral edge is the outer peripheral edge of the negative electrode. An electrical storage device, wherein the electrical storage device is disposed so as to be located inside.   2. The electric storage device according to claim 1, wherein the positive electrode is arranged so that an outer peripheral edge thereof does not coincide with the outer peripheral edge of the positive electrode of the layer adjacent to the entire circumference in the stacking direction.   The power storage device according to claim 1 or 2, wherein the plurality of positive plates are formed in the same shape, and the plurality of negative plates are formed in the same shape.   The power storage device according to any one of claims 1 to 3, wherein the power storage device is a lithium ion capacitor.

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