JP2014045002A - Electrode group for power storage device and power storage device - Google Patents

Abstract

An electrode group for an electricity storage device and an electricity storage device that suppress the formation of a portion that does not function as an electrode and suppress a decrease in energy density.
A strip-like positive electrode plate 11a having a positive electrode active material layer formed on a positive electrode current collector 13a and a strip-like negative electrode plate 11c having a negative electrode active material layer formed on a negative electrode current collector 13c are wound. The positive electrode plate 11a and the negative electrode plate 11c are overlapped and wound in a state where the positions of the innermost end portions are matched, and the positive electrode active material layer is disposed on the positive electrode plate 11a and the negative electrode plate 11c. The positive electrode active material forming part 14a and the negative electrode active material forming part 14c on which the negative electrode active material layer is arranged are provided. The positive electrode active material forming part 14a and the negative electrode active material forming part 14c are provided with the positive electrode plate 11a and the negative electrode plate 11c. The total number of positive electrode active material forming portions 14a−the total number of negative electrode active material forming portions 14c | ≦ 2.
[Selection] Figure 5

Description

  The present invention relates to an electrode group used for an electricity storage device and an electricity storage device including the electrode group.

  2. Description of the Related Art In recent years, progress in downsizing and weight reduction of electronic devices has been remarkable, and accordingly, demands for downsizing and weight reduction of batteries used as power sources for driving the electronic devices are further increased. In order to satisfy such demands for reduction in size and weight, nonaqueous electrolyte secondary batteries represented by lithium ion secondary batteries have been developed as power storage devices.

  In addition, an electric double layer capacitor is known as an electric storage device having characteristics such as high output density and good cycle performance. Further, lithium ion capacitors that combine the storage principles of lithium ion secondary batteries and electric double layer capacitors are attracting attention as power storage devices for applications that require high energy density characteristics and high output characteristics.

  In such an electricity storage device, in order to increase the energy density and the output density, it is preferable to downsize the device by using a so-called wound electrode. As a method for efficiently using the volume in the container for storing the wound electrode, a region where no active material layer is formed along the width direction is provided on both the positive and negative electrode plates, and the active material layer is not formed. There has been proposed an electrode structure in which a formation region is arranged at a bent portion of a wound electrode (see, for example, Patent Documents 1 and 2).

JP 2007-26786 A JP 2011-14238 A

  However, the electrode structures disclosed in Patent Documents 1 and 2 have a problem that there is a useless portion that does not function as an electrode, and the energy density is insufficient. That is, when the positive electrode plate and the negative electrode plate are bent to form a winding structure, a portion where the active material layer of the positive electrode plate and the active material layer of the negative electrode plate are not disposed to face each other is formed, There is a problem that the energy density that can be realized is insufficient as compared with the energy density expected from the area where the active material layer is provided.

  The present invention has been made to solve the above-described problem, and an electrode group for an electricity storage device and an electricity storage device that can suppress a decrease in energy density by suppressing formation of a portion that does not function as an electrode. The purpose is to provide.

In order to achieve the above object, the present invention provides the following means.
The electrode group for an electricity storage device of the present invention comprises a strip-like positive electrode plate in which a positive electrode active material layer is formed on a positive electrode current collector and a strip-like negative electrode plate in which a negative electrode active material layer is formed on a negative electrode current collector. A positive electrode plate and the negative electrode plate, wherein the positive electrode plate and the negative electrode plate are overlapped and wound in a state in which the positions of the innermost end portions thereof coincide with each other. Each of the plates is provided with a positive electrode active material forming part in which the positive electrode active material layer is disposed and a negative electrode active material forming part in which the negative electrode active material layer is disposed, and the positive electrode active material forming part and the negative electrode The active material forming portions are arranged separately from each other in the longitudinal direction of the positive electrode plate and the negative electrode plate, and | the total number of the positive electrode active material forming portions−the total number of the negative electrode active material forming portions | ≦ 2. It is characterized by that.

  According to the electrode group for an electricity storage device of the present invention, by setting the absolute value of the difference between the total number of positive electrode active material forming portions and the total number of negative electrode active material forming portions to 2 or less, the innermost circumference of the positive electrode plate and the negative electrode plate It is possible to suppress the formation of a portion that does not function as an electrode in the electrode group when the two ends are overlapped and wound.

  Furthermore, in order to form the electrode group by winding the electrode plate in a state where the positions of the innermost end portions of the positive electrode plate and the negative electrode plate are aligned and overlapped, for example, the position of the innermost end portion is shifted and overlapped. It becomes easier to form an electrode group as compared with the case of winding in a wound state.

  That is, when the positions of the innermost end portions of the positive electrode plate and the negative electrode plate are shifted and overlapped, it is necessary to overlap the positive electrode active material forming portion and the negative electrode active material forming portion so that the positions thereof face each other. Therefore, it is difficult to align the overlay. On the other hand, when the positions of the innermost end portions of the positive electrode plate and the negative electrode plate are matched and overlapped, the positive electrode active material forming portion and the negative electrode active portion are simply formed by matching the positions of the innermost end portions. Since the material forming portions face each other in a state where there is a position, the electrode group can be easily formed.

In the above invention, it is desirable that the positive electrode plate and the negative electrode plate have the same length in the longitudinal direction.
By making the lengths in the longitudinal direction of the positive electrode plate and the negative electrode plate equal in this way, the positive electrode active material forming portion and the negative electrode active portion are overlapped when the positive electrode plate and the negative electrode plate are overlapped as compared with the case where the lengths are different. It becomes easy to make a substance formation part oppose.

  In the above invention, it is preferable that the positive electrode plate is disposed inside the negative electrode plate in a wound state, and the total number of the positive electrode active material forming portions is equal to or less than the total number of the negative electrode active material forming portions.

  Thus, by making the total number of positive electrode active material forming portions provided on the positive electrode plate disposed on the inner side to be equal to or less than the total number of negative electrode active material forming portions, formation of portions that do not function as electrodes in the electrode group is suppressed, and energy is reduced. A decrease in density can be suppressed.

  In the above invention, the positive electrode active material layer and the negative electrode active material layer are not arranged between the adjacent positive electrode active material forming portions and between the adjacent negative electrode active material forming portions, respectively. In a state where the forming portion is provided and the positive electrode plate and the negative electrode plate are wound, the non-formed portion is bent, and the positive electrode active material forming portion and the negative electrode active material forming portion are flattened. It is preferable.

  In this way, the positive electrode plate and the negative electrode plate are bent at the unformed part, and the electrode group is formed in a flat shape in which the positive electrode active material forming part and the negative electrode active material forming part are flattened, thereby suppressing a decrease in energy density. it can. For example, compared with the case where the positive electrode active material forming portion and the negative electrode active material forming portion are bent, the positive electrode active material layer provided in the positive electrode active material forming portion and the negative electrode active material forming provided in the negative electrode active material forming portion are formed. Since stress is hard to act on the layer, problems such as breakage are less likely to occur. Therefore, it can suppress that a positive electrode active material formation part and a negative electrode active material formation part stop functioning as an electrode for reasons, such as a failure | damage, and can suppress the fall of an energy density.

  In the above invention, the negative electrode active material forming portions are separated from each other and are arranged from one end portion toward the other end portion, and are arranged with the negative electrode current collector interposed therebetween. It is preferable that the positive electrode plate is disposed only at a position facing the negative electrode active material forming portion in a state where the positive electrode plate is disposed and wound inside the negative electrode plate.

  By doing in this way, when it rolls in the state which piled up the positive electrode plate so that it might become an inner side of a negative electrode plate, the positive electrode active material formation part which mutually opposes in the center of an electrode group is lose | eliminated. In other words, a portion that does not function as an electrode in the electrode group is reduced, and a decrease in energy density in the electrode group can be suppressed.

  In the above invention, the positive electrode plate is wound in a state of being disposed inside the negative electrode plate, the negative electrode active material forming portions are separated from each other and aligned from one end portion to the other end portion, and The negative electrode active material forming part is disposed on the outermost periphery with the negative electrode current collector interposed therebetween except for the position where the negative electrode active material forming part does not face the positive electrode active material forming part. It is preferable that the positive electrode active material forming portions are arranged with the positive electrode current collector interposed therebetween except for a position where the positive electrode active material forming portions are arranged from one end portion toward the other end portion and face each other on the innermost periphery.

  By doing in this way, when it rolls in the state which piled up the positive electrode plate so that it might become an inner side of a negative electrode plate, the positive electrode active material formation part which mutually opposes in the center of an electrode group is lose | eliminated. Furthermore, the single negative electrode active material formation part which does not oppose the positive electrode active material formation part on the outer periphery of an electrode group is lose | eliminated. In other words, the portion not functioning as an electrode in the electrode group and in the outer periphery is reduced, and a decrease in energy density in the electrode group can be suppressed.

  The electrode group for an electricity storage device of the present invention comprises a belt-like positive electrode plate having a positive electrode active material layer formed on a positive electrode current collector and a belt-like negative electrode plate having a negative electrode active material layer formed on a negative electrode current collector. , An electrode group for an electricity storage device wound in a state where the positive electrode plate is disposed inside the negative electrode plate, wherein the positive electrode plate has a positive electrode active material forming portion in which the positive electrode active material layer is disposed. The negative electrode plate is provided with a negative electrode active material forming portion on which the negative electrode active material layer is disposed, and the negative electrode plate has two negative electrode active material forming portions on both sides of the negative electrode current collector. The positive electrode active material forming part and the negative electrode active material forming part are arranged separately from each other in the longitudinal direction of the positive electrode plate and the negative electrode plate, and the positive electrode plate and the negative electrode plate are The positive electrode active material closest to the innermost end of the positive electrode plate Formation portion, wherein the negative active material forming part close to the second from the one end of the negative electrode plate is characterized in that it is wound superimposed in a state facing each other.

  According to the electrode group for an electricity storage device of the present invention, when the positive electrode plate and the negative electrode plate are wound in an overlapped state, the innermost one end of the positive electrode plate is sandwiched between the negative electrode plates. The positive electrode active material forming portions do not face each other at the center. In other words, it is difficult to form a portion that does not function as an electrode inside the electrode group, and a decrease in energy density in the electrode group can be suppressed.

The electricity storage device of the present invention is characterized in that the electricity storage device electrode group of the present invention, an electrolyte, and a case for housing the electrode group and the electrolyte are provided.
According to the electricity storage device of the present invention, since the electrode group for an electricity storage device of the present invention is provided, formation of a portion that does not function as an electrode inside the electrode group is suppressed, and a high energy density is realized. be able to.

  According to the electrode group for an electricity storage device and the electricity storage device of the present invention, the absolute value of the difference between the total number of the positive electrode active material forming portions and the total number of the negative electrode active material forming portions is 2 or less. When overlapping and winding in the state where the position of the innermost end is matched, it is possible to suppress the formation of a portion that does not function as an electrode, and to suppress a decrease in energy density. Play.

It is a schematic diagram explaining the whole structure of the electrical storage device which concerns on the 1st Embodiment of this invention. FIG. 2 is a schematic AA sectional view for explaining the configuration of an electrode group in FIG. 1. It is AA sectional view explaining the size of the electrode group of FIG. It is a schematic diagram explaining the structure of the positive electrode plate and negative electrode plate of FIG. It is a schematic diagram explaining the arrangement | positioning and structure of the positive electrode plate of FIG. 2, a negative electrode plate, and a separator. It is sectional drawing explaining the structure of a positive electrode active material formation part or a negative electrode active material formation part. It is sectional drawing explaining the difference in a structure of a positive electrode active material formation part and a negative electrode active material formation part. FIG. 3 is a schematic diagram for explaining a superimposed state of the positive electrode plate and the negative electrode plate of FIG. 2. It is a schematic diagram explaining arrangement | positioning of the electrode group of the electrical storage device which concerns on another embodiment of this invention, a positive electrode tab lead, and a negative electrode tab lead. FIG. 10 is a C-C ′ sectional view for explaining the overall configuration of the electricity storage device of FIG. 9. It is a model cross section explaining the structure of the electrode group of the electrical storage device which concerns on the 2nd Embodiment of this invention. It is a schematic diagram explaining the arrangement | positioning and structure of the positive electrode plate of FIG. 11, a negative electrode plate, and a separator. It is a model cross section explaining the structure of the electrode group of the electrical storage device which concerns on the 3rd Embodiment of this invention. It is a schematic diagram explaining the arrangement | positioning and structure of the positive electrode plate of FIG. 13, a negative electrode plate, and a separator.

[First Embodiment]
Hereinafter, an electricity storage device 1 according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 9. In the present embodiment, description will be made by applying to an example in which the electricity storage device 1 is a lithium ion capacitor. The electricity storage device 1 may be a lithium ion capacitor as described above, or may be a lithium ion battery or an electric double layer capacitor, and the form thereof is not particularly limited.

  As shown in the schematic diagram of FIG. 1, the electricity storage device 1 includes an electrode group 10, a positive electrode tab lead (extraction terminal) 31 a and a negative electrode tab lead (extraction terminal) 31 c, and a laminated exterior type square case (case) 41. Are mainly provided.

  The electrode group 10 is a central component that performs charging and discharging in the electricity storage device 1. As shown in the schematic cross-sectional view of the electrode group 10 in FIG. 2, the electrode group 10 is mainly composed of a positive electrode plate 11a, a negative electrode plate 11c, and a separator 21, and the negative electrode plate 11c, the separator 21, and the positive electrode plate 11a. The layers laminated in the order of the separator 21 are wound in a flat shape.

  In addition, the electrode group 10 shown in FIG. 2 shows the number of windings as three for easy understanding, and does not limit the number of windings to three. The number of windings may be three or more, and the number is not limited. In the present embodiment, description will be made by applying to an example in which the number of windings in the electrode group 10 is 20.

  Here, the number of windings means the number of windings in the positive electrode plate 11a and the negative electrode plate 11c, and means the number of windings excluding a lead portion 15 provided on the positive electrode plate 11a and the negative electrode plate 11c described later. To do. In other words, it does not mean the number of windings in the separator 21. In the electrode group 10 of this embodiment, the separator 21 is wound one more time than the positive electrode plate 11a and the negative electrode plate 11c, and covers the outermost periphery of the electrode group 10. In the actual electrode group 10, the positive electrode plate 11a, the negative electrode plate 11c, and the separator 21 are wound in a stacked state. The separator 21 may be wound two to three times more than the positive electrode plate 11a and the negative electrode plate 11c.

  FIG. 3 is a diagram showing the size of the electrode group 10 in the present embodiment. The innermost circumferential winding width Win of the electrode group 10 is 86 (mm), and the minimum radius R is 0.5 (mm) or less. The winding width Wout is 93 (mm), and the thickness T is 7.2 + 2R (mm). The width Wp of the region where the positive electrode active material forming portion 14a of the positive electrode plate 11a described later and the negative electrode active material forming portion 14c of the negative electrode plate 11c are formed is 79.6 (mm) in the positive electrode active material forming portion 14a. In the negative electrode active material formation part 14c, it is 81.6 (mm).

  Moreover, the thickness t of the layer laminated | stacked in order of the negative electrode plate 11c, the separator 21, the positive electrode plate 11a, and the separator 21 is 350 (micrometer) (refer FIG. 2). Among them, the thickness of the positive electrode plate 11a is 190 (μm), the thickness of the negative electrode plate 11c is 100 (μm), and the total thickness of the two separators 21 is 60 (μm).

  As shown in FIGS. 4A and 5, the positive electrode plate 11a includes a positive electrode current collector 13a, a positive electrode active material forming portion 14a provided with a positive electrode active material layer, a lead portion 15, and a first unformed portion. It is mainly formed from the portion 16, the second unformed portion 17, the third unformed portion (unformed portion) 18, and the positive electrode lead terminal arrangement portion 19a. 4B and 5, the negative electrode plate 11c includes a negative electrode current collector 13c, a negative electrode active material forming portion 14c provided with a negative electrode active material layer, a lead portion 15, and a first portion. This is mainly formed from the non-formed portion 16, the second non-formed portion 17, the third non-formed portion 18, and the negative electrode lead terminal arrangement portion 19c.

  The positive electrode current collector 13a is a film-like member having conductivity, and can conduct electricity between the positive electrode active material forming portion 14a and the positive electrode tab lead 31a. An insulating film may be provided on the surface of the positive electrode current collector 13a except for a region where the positive electrode active material forming portion 14a and the positive electrode tab lead 31a are formed. Examples of the material of the positive electrode current collector 13a include aluminum and stainless steel. Moreover, as a material which comprises an insulating film, resin materials, such as a polyimide type and an epoxy type, can be mentioned, for example.

  The negative electrode current collector 13c is a film-like member having conductivity, and can conduct electricity between the negative electrode active material forming portion 14c and the negative electrode tab lead 31c. An insulating film may be provided on the surface of the negative electrode current collector 13c except for a region where the negative electrode active material forming portion 14c and the negative electrode tab lead 31c are formed. Examples of the material of the negative electrode current collector 13c include copper and stainless steel. Moreover, as a material which comprises an insulating film, resin materials, such as a polyimide type and an epoxy type, can be mentioned, for example.

  The positive electrode active material forming portion 14a is a rectangular region provided on the positive electrode current collector 13a, and is a portion where a layer of the positive electrode active material is provided. As the positive electrode active material for forming the positive electrode active material layer, for example, activated carbon powder, a conductive polymer, a polyacene organic semiconductor, or the like can be used.

  In the positive electrode plate 11a of the present embodiment, the positive electrode active only on the surface facing the negative electrode plate 11c at the position P1 closest to the lead portion 15 which is the innermost end of the electrode group 10 and the position P2 closest to the next. A substance forming portion 14a is provided. The positive electrode active material forming portion 14a is not provided on the surface opposite to the negative electrode plate 11c. The positive electrode active material forming portion 14a is provided so as to sandwich the positive electrode plate 11a at a position far from the third closest position P3. Therefore, in this embodiment, 38 layers of positive electrode active material forming portions 14a are provided on the positive electrode plate 11a.

  The negative electrode active material forming portion 14c is a rectangular region provided on the negative electrode current collector 13c, and is a portion where a layer of the negative electrode active material is provided. As the negative electrode active material forming the negative electrode active material layer, for example, graphite, hard carbon, polyacene organic semiconductor, or the like can be used, and lithium ions are occluded and supported on the negative electrode active material. In the present embodiment, since the negative electrode active material forming portion 14c is provided so as to sandwich the negative electrode plate 11c at all positions, the 40 layers of the negative electrode active material forming portion 14c are provided.

  The positive electrode active material layer and the negative electrode active material layer are formed by applying and drying a slurry in which a positive electrode active material or a negative electrode active material is dispersed in a solvent together with a binder or the like on a current collector by intermittent coating or the like. be able to. The positive electrode active material layer and the negative electrode active material layer thus formed usually form a raised portion BP at the end portions of the positive electrode active material forming portion 14a and the negative electrode active material forming portion 14c, respectively, as shown in FIG. To do. In the present embodiment, description will be made by applying to an example in which the height H of the raised portion BP is 5 (μm) or less. If the height H of the raised portion BP is too high, the electrode plate may be deformed when the electrode plate is wound into a roll shape, the internal resistance or capacity of the electricity storage device may vary, or the electrode plate may be wound. In some cases, problems such as being bulky and not being able to fit within a predetermined size are likely to occur.

  The positive electrode active material forming portions 14a are discretely arranged at intervals in the longitudinal direction (vertical direction in FIG. 4A) of the strip-like positive electrode plate 11a, and the negative electrode active material forming portions 14c are longitudinally arranged in the strip-like negative electrode plate 11c. It is discretely arranged at intervals in the direction (vertical direction in FIG. 4B). Around the positive electrode active material forming portion 14a and the negative electrode active material forming portion 14c, a first unformed portion 16, a second unformed portion 17, and a third unformed portion 18 are mainly arranged.

  In addition, as shown in FIG. 7, when the positive electrode active material forming portion 14a and the negative electrode active material forming portion 14c are arranged to face each other with the center aligned, in other words, the positive electrode active material layer and the negative electrode active material layer are arranged to face each other. The end portion of the positive electrode active material forming portion 14a is formed to be located inside the negative electrode active material forming portion 14c. The end portion of the positive electrode active material forming portion 14a is preferably located on the inner side in the range of 0.1 (mm) to 5 (mm) than the end portion of the negative electrode active material forming portion 14c.

  The lead portion 15 includes a positive electrode active material layer provided at one end portion in the longitudinal direction of the positive electrode plate 11a and the negative electrode plate 11c, more specifically, an end portion that becomes inward when wound, and a negative electrode active material layer. The material layer is not provided.

  The first unformed portion 16, the second unformed portion 17 and the third unformed portion 18 are a portion of the positive electrode plate 11a where the positive electrode active material forming portion 14a is not provided, or a negative electrode active in the negative electrode plate 11c. This is a portion where the material forming portion 14c is not provided.

  The first unformed portion 16 is a portion extending in the longitudinal direction at one end portion of the pair of long sides in the positive electrode plate 11a, or a portion extending in the longitudinal direction at one end portion of the pair of long sides in the negative electrode plate 11c. It is.

  The second unformed portion 17 is a portion extending in the longitudinal direction at the other end of the pair of long sides in the positive electrode plate 11a, or a portion extending in the longitudinal direction at the other end of the pair of long sides in the negative electrode plate 11c. It is. The second unformed portion 17 is formed to have a narrower length in the lateral width direction (the left-right direction in FIGS. 4A and 4B) than the first unformed portion 16.

  The third unformed portion 18 is a portion extending from one of the pair of long sides to the other between the adjacent positive electrode active material forming portions 14a or between the adjacent negative electrode active material forming portions 14c. Is a portion extending from one of the pair of long sides toward the other in the negative electrode plate 11c. The third unformed portion 18 is a portion that is bent when a layer in which the negative electrode plate 11c, the separator 21, the positive electrode plate 11a, and the separator 21 are laminated in this order is wound in a flat shape.

  In addition, the length of the third unformed portion 18 in the horizontal width direction (vertical direction in FIGS. 4A and 4B) is a third distance far from the third unformed portion 18 close to the lead portion 15. It is formed so as to be continuously widened toward the non-formed part 18. In other words, the distances L1, L2, L3,... Between the centers of the adjacent positive electrode active material forming portion 14a or the adjacent negative electrode active material forming portion 14c are continuously increased as the distance from the lead portion 15 increases. Is formed.

  The positive electrode lead terminal arrangement portion 19a is a portion where the positive electrode tab lead 31a is arranged, and is a portion where the positive electrode current collector 13a of the positive electrode plate 11a is exposed without being covered with an insulating film. The positive electrode lead terminal arrangement part 19a is the first unformed part 16 of the positive electrode plate 11a, and is arranged side by side with the positive electrode active material formation part 14a. The negative electrode lead terminal arrangement portion 19c is a portion where the negative electrode tab lead 31c is arranged, and is a portion where the negative electrode current collector 13c of the negative electrode plate 11c is exposed without being covered with an insulating film. The negative electrode lead terminal arrangement part 19c is the first unformed part 16 of the negative electrode plate 11c, and is arranged side by side with the negative electrode active material formation part 14c.

  As shown in FIGS. 2 and 5, the separator 21 is disposed between the positive electrode plate 11a and the negative electrode plate 11c so that the positive electrode plate 11a and the negative electrode plate 11c wound in a flat shape do not come into contact with each other. It is. The inner end portion (lower end portion in FIG. 5) of the winding structure in the separator 21 is arranged so as to protrude as compared with the end portions of the positive electrode plate 11a and the negative electrode plate 11c. By doing in this way, the short circuit with the positive electrode plate 11a and the negative electrode plate 11c in an inner edge part is suppressed. Moreover, as shown in FIG. 2, one of the pair of separators 21 included in the electrode group 10 is formed such that the outer end of the winding structure is longer than the positive electrode plate 11a and the negative electrode plate 11c. The outermost periphery of the group 10 is covered.

  As the separator 21, for example, a nonwoven fabric formed from glass fiber, cellulose fiber, polypropylene fiber, or the like can be used. The separator 21 is impregnated with an electrolytic solution. As the electrolytic solution, for example, an aprotic organic solvent electrolyte solution of a lithium salt can be used.

Examples of the anion constituting the lithium salt include PF ₆ ⁻ , BF ₄ ⁻ , A _S F ₆ ⁻ , SbF ₆ ⁻ , N (CF ₃ SO ₃ ) ₂ ⁻ , C (CF ₃ SO ₃ ) ₃ ⁻ , CF ₃ (SO ₃ ) ⁻ , F ⁻ , ClO ₄ ⁻ , AlF ₄ ⁻ , TaF ₆ ⁻ , NbF ₆ ⁻ , SiF ₆ ⁻ , CN ⁻ , F (HF) _n ^{− and the} like.

  Examples of the aprotic organic solvent include propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, sphoran, methyl sulfolane, acetonitrile, fluorinated γ-butyrolactone, γ-butyrolactone, fluorinated propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, Examples include diethyl carbonate.

  Next, an overlapping state of the positive electrode plate 11a and the negative electrode plate 11c will be described with reference to FIG. In FIG. 8, the state in which the positive electrode plate 11a and the negative electrode plate 11c are overlapped is viewed from the negative electrode plate 11c side.

  The positive electrode plate 11a and the negative electrode plate 11c are overlapped so that the positive electrode active material forming portion 14a and the negative electrode active material forming portion 14c face each other. Further, in the positive electrode plate 11a and the negative electrode plate 11c, the first unformed portion 16 of the positive electrode plate 11a and the second unformed portion 17 of the negative electrode plate 11c face each other, and the second unformed portion of the positive electrode plate 11a. 17 and the first unformed portion 16 of the negative electrode plate 11c are overlapped so as to face each other.

  More specifically, the end portion of the second unformed portion 17 in the negative electrode plate 11c is disposed 8 (mm) inside from the end portion of the first unformed portion 16 in the positive electrode plate 11a. Similarly, the end portion of the second unformed portion 17 in the positive electrode plate 11a is disposed 8 (mm) inside from the end portion of the first unformed portion 16 in the negative electrode plate 11c. The positive electrode plate 11a and the negative electrode plate 11c are overlapped so that there is an interval of 100 (mm) from the end of the first unformed part 16 in the positive electrode plate 11a to the end of the first unformed part 16 in the negative electrode plate 11c. Has been.

  Furthermore, the positive electrode lead terminal arrangement portion 19a and the negative electrode lead terminal arrangement portion 19c are 5 mm from the end of the first unformed portion 16 toward the center and 50 mm in the direction along the long side. ) As a rectangular region.

  Further, the separator 21 is formed to have a length of 86 (mm) in the horizontal width direction (the vertical length in FIG. 8). One end portion (the upper end portion in FIG. 8) of the separator 21 is arranged 8 (mm) inside from the end portion of the first unformed portion 16 in the positive electrode plate 11a, and the other end portion (in FIG. 8). The lower end) is disposed 8 (mm) inside from the end of the first unformed portion 16 in the negative electrode plate 11c.

  As shown in FIGS. 1 and 8, the positive electrode tab lead 31a extends in the lateral width direction (vertical direction in FIG. 8) of the positive electrode plate 11a and is electrically connected to the positive electrode plate 11a. The negative electrode tab lead 31c extends in the lateral width direction of the negative electrode plate 11c and is connected to the negative electrode plate 11c so as to be conductive.

  Specifically, the positive electrode tab lead 31a is electrically connected by welding or the like in the positive electrode extraction terminal arrangement portion 19a of the positive electrode plate 11a, and the negative electrode tab lead 31c is in the negative electrode extraction terminal arrangement portion 19c of the negative electrode plate 11c.

  As shown in FIG. 1, the positive electrode tab lead 31a and the negative electrode tab lead 31c are disposed through the rectangular case 41, and when the current is discharged from the electrode group 10 to the outside, or the electrode group 10 is charged from the outside. It is a terminal used when doing.

The square case 41 is a container in which both ends of the electrode group 10, the positive electrode tab lead 31a and the negative electrode tab lead 31c, and the electrolyte solution are stored.
According to the electrode group 10 (power storage device 1) having the above-described configuration, the positive electrode plate 11a and the negative electrode plate are obtained by subtracting the total number of the positive electrode active material forming portions 14a from the total number of the negative electrode active material forming portions 14c to 2. It is possible to suppress the formation of a portion that does not function as an electrode in the electrode group 10 when winding is performed in a state where the positions of the innermost end portions of 11c are made to coincide with each other.

  That is, when the positive electrode plate 11a is wound so as to be inside the negative electrode plate 11c, the positive electrode active material forming portions 14a that face each other at the center of the electrode group 10 are eliminated. In other words, the portion that does not function as an electrode in the electrode group 10 is reduced, and a decrease in energy density in the electrode group 10 can be suppressed.

  Furthermore, in order to form the electrode group 10 by winding in a state where the positions of the innermost end portions of the positive electrode plate 11a and the negative electrode plate 11c are aligned and overlapped, for example, the position of the innermost end portion is shifted. Thus, the electrode group 10 can be formed more easily than in the case of winding in an overlapped state.

  That is, when the positions of the innermost peripheral edge portions of the positive electrode plate 11a and the negative electrode plate 11c are shifted and overlapped, the positive electrode active material forming portion 14a and the negative electrode active material forming portion 14c are aligned to face each other. Since it is necessary to superimpose, it has been difficult to align the overlay. On the other hand, when the positions of the innermost end portions of the positive electrode plate 11a and the negative electrode plate 11c are made to coincide with each other, the positive electrode active material forming portion 14a can be obtained only by matching the positions of the innermost end portions. Since the electrodes face each other in a state where the negative electrode active material forming portion 14c is located, the electrode group 10 can be easily formed.

  Furthermore, by making the lengths in the longitudinal direction of the positive electrode plate 11a and the negative electrode plate 11c equal, the positive electrode active material forming portion 14a is formed when the positive electrode plate 11a and the negative electrode plate 11c are overlapped as compared with the case where the lengths are different. And it becomes easy to make the negative electrode active material formation part 14c oppose.

  Moreover, according to the electrode group 10 (power storage device 1) having the above-described configuration, the total area of the negative electrode active material forming portion is relatively larger than the total area of the positive electrode active material forming portion. It can also suppress that it precipitates in a needle shape and a positive and negative electrode short-circuits.

  The positive electrode plate 11a and the negative electrode plate 11c are bent at the third unformed part 18, and the electrode group 10 is formed in a flat shape in which the positive electrode active material forming part 14a and the negative electrode active material forming part 14c are flattened. It is possible to suppress a decrease in energy density. For example, as compared with the case where the positive electrode active material forming part 14a and the negative electrode active material forming part 14c are bent, the positive electrode active material layer provided in the positive electrode active material forming part 14a or the negative electrode active material forming part 14c is provided. Since stress is unlikely to act on the negative electrode active material forming layer, defects such as breakage are less likely to occur. Therefore, it can suppress that the positive electrode active material formation part 14a and the negative electrode active material formation part 14c do not function as an electrode for reasons, such as a failure | damage, and the high energy density of the electrical storage device 1 can be implement | achieved.

  As shown in FIG. 9, the positive electrode tab lead 31a and the negative electrode tab lead 31c may be arranged extending in the longitudinal direction of the positive electrode plate 11a or the negative electrode plate 11c. In other words, the positive electrode tab lead 31a and the negative electrode tab lead 31c may be formed to extend in the same direction by rotating the direction in which the positive electrode tab lead 31a and the negative electrode tab lead 31c are pulled out by about 90 ° as compared with the above-described embodiment. .

  FIG. 10 shows a configuration of the electricity storage device 1 having the electrode group 10 shown in FIG. In this case, the positive electrode tab lead 31a and the negative electrode tab lead 31c are electrically connected to the first unformed portion 16 of the positive electrode plate 11a and the first unformed portion 16 of the negative electrode plate 11c, respectively, whose ends are combined. It is connected to the.

  The square case 41 is a container formed of alumite-treated metal, and its thickness is about 0.2 (mm). The square case 41 shown in FIG. 10 is directed from the portion housing the electrode group 10 toward the portion where the positive electrode tab lead 31a and the negative electrode tab lead 31c are welded (on the positive electrode tab lead 31a side, from the right to the left in FIG. On the tab lead 31c side, from the left to the right in FIG.

  That is, the first step is formed in a region from the portion in which the electrode group 10 is accommodated toward the portion where the positive electrode tab lead 31a and the negative electrode tab lead 31c are welded to the positive electrode tab lead 31a and the negative electrode tab lead 31c. The second level difference is from the portion where the positive electrode tab lead 31a and the negative electrode tab lead 31c are welded to the first unformed portion 16 of the positive electrode plate 11a and the first unformed portion 16 of the negative electrode plate 11c. Is formed in a region toward the portion to be fused.

  The first step portion has a length of about 3 (mm) as shown in FIG. The portion where the positive electrode tab lead 31a and the negative electrode tab lead 31c are welded to the first unformed portion 16 of the positive electrode plate 11a and the first unformed portion 16 of the negative electrode plate 11c has a length of about 3 (mm). Yes. The portion to which the square case 41 is fused has a length of about 10 mm.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. 11 and FIG. The basic configuration of the electricity storage device of this embodiment is the same as that of the first embodiment, but the configuration of the electrode group is different from that of the first embodiment. Therefore, in the present embodiment, only the configuration of the electrode group will be described with reference to FIGS. 11 and 12, and description of other components and the like will be omitted.

  The electrode group 110 of the electricity storage device 101 according to the present embodiment is mainly composed of a positive electrode plate 11a, a negative electrode plate 111c, and a separator 21, as shown in the schematic cross-sectional view of the electrode group 110 in FIG. A layer in which the plate 111c, the separator 21, the positive electrode plate 11a, and the separator 21 are laminated in this order is wound in a flat shape. In the electrode group 110 shown in FIG. 11, the number of windings is shown as three for easy understanding, and the number of windings is not limited to three.

  In the present embodiment, description will be made by applying to an example in which the number of windings in the electrode group 110 is 20. Further, in the actual electrode group 110, the positive electrode plate 11a, the negative electrode plate 111c, and the separator 21 are wound in a stacked state.

  As shown in FIG. 12, the negative electrode plate 111c is mainly formed from a negative electrode current collector 13c, a negative electrode active material forming portion 14c, a lead portion 15, and a third unformed portion 18. . The negative electrode plate 111c is provided with a first non-formed portion 16, a second non-formed portion 17, and a negative electrode lead terminal arrangement portion 19c, similarly to the negative electrode plate 11c of the first embodiment. (See FIG. 4B).

  In the negative electrode plate 111c of the present embodiment, at the position P20 closest to the outermost end (upper end in FIG. 12) of the electrode group 10 and the position P19 closest to the next, the surface facing the positive electrode 11a. Only the negative electrode active material forming portion 14c is provided. The negative electrode active material forming portion 14c is not provided on the surface opposite to the positive electrode plate 11a. The negative electrode active material forming portion 14c is provided so as to sandwich the negative electrode plate 111c at a position close to the lead portion 15 from the third closest position P18. Therefore, in the present embodiment, 38 negative electrode active material forming portions 14c are provided on the negative electrode plate 111c, and the total number of negative electrode active material forming portions 14c is the positive electrode active material forming portion 14a provided on the positive electrode plate 11a. It becomes the same as the total number.

  According to the electrode group 110 (power storage device 101) having the above-described configuration, the positive electrodes facing each other at the center of the electrode group 110 when the positive electrode plate 11a is wound in a superimposed state so as to be inside the negative electrode plate 111c. The active material forming part 14a is eliminated. In other words, the positive electrode active material forming portions 14a are located at the center of the electrode group 110 (specifically, the opposite positive electrode active material forming portion 14a at the position P1 and the opposite positive electrode active material forming portion 14a at the position P2). ) No longer facing each other.

  Further, on the outer periphery of the electrode group 110, a single negative electrode active material forming portion 14c that does not face the positive electrode active material forming portion 14a (specifically, the negative electrode active material forming portion 14c on the opposite side at the position P19 and the opposite at position P20) The negative electrode active material forming part 14c) on the side is eliminated. In other words, the portions that do not function as electrodes in the electrode group 110 and in the outer periphery are reduced, and a decrease in energy density in the electrode group 110 can be suppressed.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIGS.
The basic configuration of the electricity storage device of this embodiment is the same as that of the first embodiment, but the configuration of the electrode group is different from that of the first embodiment. Therefore, in the present embodiment, the configuration of the electrode group will be described with reference to FIGS. 13 and 14, and description of other components and the like will be omitted.

  The electrode group 210 of the electricity storage device 201 according to the present embodiment is mainly composed of a positive electrode plate 211a, a negative electrode plate 211c, and a separator 21, as shown in the schematic cross-sectional view of the electrode group 210 in FIG. A layer in which the plate 211c, the separator 21, the positive electrode plate 211a, and the separator 21 are laminated in this order is wound in a flat shape. In the electrode group 210 shown in FIG. 13, the number of windings is shown as three for easy understanding, and the number of windings is not limited to three.

  In the present embodiment, description will be made by applying to an example in which the number of windings in the electrode group 210 is 20. Further, in the actual electrode group 210, the positive electrode plate 211a, the negative electrode plate 211c, and the separator 21 are wound in a stacked state.

  As shown in FIG. 14, the positive electrode plate 211 a is mainly formed from a positive electrode active material forming portion 14 a and a third unformed portion 18. The positive electrode plate 211a has a positive electrode current collector 13a, a first non-formed part 16, a second non-formed part 17, and a positive electrode lead terminal arrangement, similarly to the negative electrode plate 11c of the first embodiment. A portion 19a is provided (see FIG. 4A).

  Unlike the positive electrode plate 11a of the first embodiment, the positive electrode plate 211a of the present embodiment is different from the positive electrode plate 11a of the first embodiment in that the positive electrode plate 211a is sandwiched from the innermost end of the electrode group 210. A substance forming portion 14a is provided. Since the positive electrode active material forming portion 14a is provided at 20 positions on the positive electrode plate 211a, a total of 40 positive electrode active material forming portions 14a are provided on the positive electrode plate 11a.

  As shown in FIG. 14, the negative electrode plate 211 c is mainly formed from a negative electrode active material forming part 14 c and a third unformed part 18. The negative electrode plate 211c has a negative electrode current collector 13c, a first non-formed part 16, a second non-formed part 17, and a negative electrode lead terminal arrangement, as with the negative electrode plate 11c of the first embodiment. And a portion 19c (see FIG. 4B).

  The negative electrode plate 211c of the present embodiment is formed longer in the longitudinal direction (vertical direction in FIG. 14) than the positive electrode plate 211a, and compared with the negative electrode plate 11c of the first embodiment, the negative electrode active material forming portion 14c. The position where is provided is increased by one. Therefore, in this embodiment, 42 negative electrode active material forming portions 14c are provided on the negative electrode plate 111c.

  When the positive electrode plate 211a and the negative electrode plate 211c are wound into the electrode group 210, the positive electrode active material forming portion 14a at the position P1 closest to the innermost end portion of the positive electrode plate 211a is the end of the negative electrode plate 211c. The negative electrode active material forming part 14c at the position P2 closest to the part is overlaid in a state of facing each other. Next, the negative electrode active material forming portion 14c at the position P1 in the negative electrode plate 211c is bent so as to sandwich the positive electrode active material forming portion 14a at the position P1, as indicated by an arrow in FIG. After that, as in the first embodiment, the positive electrode plate 211a and the negative electrode plate 211c are wound to form the electrode group 210.

  According to the electrode group 210 (power storage device 201) configured as described above, when the positive electrode plate 211a and the negative electrode plate 211c are wound in an overlapped state, the innermost end of the positive electrode plate 211a is attached to the negative electrode plate 211c. Therefore, the positive electrode active material forming part 14a (specifically, the positive electrode active material forming part 14a at the position P1 and the positive electrode active material forming part 14a at the position P2) is formed at the center of the electrode group 210. Opposite. In other words, a portion that does not function as an electrode is not easily formed in the electrode group 210, and a decrease in energy density in the electrode group 210 can be suppressed.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the present invention is not limited to those applied to the above-described embodiments, and may be applied to embodiments obtained by appropriately combining these embodiments, and is not particularly limited.

  DESCRIPTION OF SYMBOLS 1,101,201 ... Power storage device 10,110,210 ... Electrode group, 11a, 211a ... Positive electrode plate, 11c, 111c, 211c ... Negative electrode plate, 13a ... Positive electrode current collector, 13c ... Negative electrode current collector, 14a ... Positive electrode active material forming part, 14c ... Negative electrode active material forming part, 18 ... Third unformed part (unformed part), 41 ... Square case (case)

Claims (8)

An electrode group for a power storage device in which a belt-like positive electrode plate having a positive electrode active material layer formed on a positive electrode current collector and a belt-like negative electrode plate having a negative electrode active material layer formed on a negative electrode current collector are wound. Because
The positive electrode plate and the negative electrode plate are overlapped and wound in a state where the positions of the innermost end portions are matched,
Each of the positive electrode plate and the negative electrode plate is provided with a positive electrode active material forming part in which the positive electrode active material layer is arranged, and a negative electrode active material forming part in which the negative electrode active material layer is arranged,
The positive electrode active material forming portion and the negative electrode active material forming portion are disposed separately from each other in the longitudinal direction of the positive electrode plate and the negative electrode plate,
| Total number of the positive electrode active material forming parts−Total number of the negative electrode active material forming parts | ≦ 2.   2. The electrode group for an electricity storage device according to claim 1, wherein the positive electrode plate and the negative electrode plate have the same length in the longitudinal direction. In the wound state, the positive electrode plate is disposed inside the negative electrode plate,
The total number of said positive electrode active material formation parts is below the total number of said negative electrode active material formation parts, The electrode group for electrical storage devices of Claim 1 or 2 characterized by the above-mentioned. Between the adjacent positive electrode active material forming portions and between the adjacent negative electrode active material forming portions, unformed portions where the positive electrode active material layer and the negative electrode active material layer are not disposed are provided, respectively. ,
In the state where the positive electrode plate and the negative electrode plate are wound, the unformed portion is bent, and the positive electrode active material forming portion and the negative electrode active material forming portion are flattened flat. The electrode group for an electricity storage device according to any one of claims 1 to 3. The negative electrode active material forming portions are separated from each other and arranged from one end portion toward the other end portion, and are arranged with the negative electrode current collector interposed therebetween,
The positive electrode active material forming part is arranged only at a position facing the negative electrode active material forming part in a state where the positive electrode plate is arranged and wound inside the negative electrode plate. Item 5. The electrode group for an electricity storage device according to any one of Items 1 to 4. The positive electrode plate is wound in a state of being disposed inside the negative electrode plate,
The negative electrode active material forming portions are separated from each other and are arranged from one end portion toward the other end portion, and a position where the negative electrode active material formation portion does not face the positive electrode active material formation portion at the outermost periphery. Except for the negative electrode current collector,
The positive electrode active material forming portions are separated from each other and are arranged from one end portion toward the other end portion, and the positive electrode active material forming portions are arranged except for a position where the positive electrode active material forming portions face each other on the innermost periphery The electrode group for an electricity storage device according to any one of claims 1 to 4, wherein the electrode group is disposed with an electric body interposed therebetween. A belt-like positive electrode plate having a positive electrode active material layer formed on a positive electrode current collector and a belt-like negative electrode plate having a negative electrode active material layer formed on a negative electrode current collector. An electrode group for an electricity storage device wound in a state of being arranged in
The positive electrode plate is provided with a positive electrode active material forming portion in which the positive electrode active material layer is disposed with the positive electrode current collector interposed therebetween,
The negative electrode plate is provided with two more negative electrode active material forming portions on which the negative electrode active material layer is disposed, with the negative electrode current collector interposed therebetween, than the positive electrode active material forming portion,
The positive electrode active material forming portion and the negative electrode active material forming portion are disposed separately from each other in the longitudinal direction of the positive electrode plate and the negative electrode plate,
In the positive electrode plate and the negative electrode plate, the positive electrode active material forming portion closest to one end portion of the innermost periphery of the positive electrode plate is second closest to the one end portion of the negative electrode plate. An electrode group for an electricity storage device, wherein the forming portions are overlapped and wound in a state of facing each other. The electrode group for an electricity storage device according to any one of claims 1 to 7,
Electrolyte,
A case housing the electrode group and the electrolyte;
An electricity storage device comprising: