JP2017147367A - Electrochemical device and electrochemical device manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrochemical device superior in productivity and reliability, and a method for manufacturing the electrochemical device.SOLUTION: An electrochemical device according to the present invention is arranged by laminating a positive electrode, a negative electrode and separators, and winding them so that a first principal face the negative electrode and a third principal face of the positive electrode are put on an inner side of the winding, and a second principal face of the negative electrode and a fourth principal face of the positive electrode are located on an outer side of the winding. In the electrochemical device, the separators serve to separate the positive and negative electrodes from each other. The first principal face has: a first region opposed to the positive electrode; and a second region located on an outermost side of the winding and protruding from an end of the positive electrode, and not opposed to the positive electrode. The second principal face has: a third region on a side opposite to the first region; and a fourth region on a side opposite to the second region. The fourth region includes an uncoated region where no negative electrode active material layer is formed. In the electrochemical device, metallic lithium is joined to the uncoated region, and lithium ions are pre-doped to a negative electrode active material layer by immersion in an electrolytic solution.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an electrochemical device having a power storage element configured by winding a positive electrode, a negative electrode, and a separator, and a method for manufacturing the electrochemical device.

  2. Description of the Related Art In recent years, electrochemical devices such as capacitors have attracted attention as a main power source or auxiliary power source for clean energy storage systems such as sunlight and wind power generation, automobiles, and hybrid electric vehicles. Here, the electric double layer capacitor has high output but low capacity, and the battery has high capacity but low output. Therefore, a lithium ion capacitor having a positive electrode as a polarizable electrode and a negative electrode as an electrode capable of occluding lithium has higher output than a battery and higher capacity than an electric double layer capacitor. Is spreading.

  On the other hand, a lithium ion capacitor requires a process called pre-doping for doping lithium ions into the negative electrode. For example, Patent Document 1 discloses a lithium ion capacitor in which a metal lithium plate for occluding or doping lithium ions is wound in an electrode group.

  Patent Document 2 discloses a lithium ion storage element in which an active material layer is stacked on a negative electrode current collector, and a region in which no active material layer is stacked is formed on the negative electrode current collector, and a lithium ion storage element is formed in the region. Is arranged and pre-doped.

  Patent Document 3 discloses that at least two separators are sandwiched between a positive electrode and a negative electrode adjacent to a lithium metal that is a lithium ion supply source, so that a predetermined amount of lithium ions can be obtained without a short circuit or the like. A lithium ion capacitor capable of doping the negative electrode is disclosed.

JP 2011-139006 A JP 2010-232565 A Japanese Patent No. 2009-059732

  In the electrochemical device that requires lithium ion pre-doping as described above, the lithium source is disposed by attaching lithium to the lithium current collector and connecting the lithium current collector to the negative electrode current collector. There is. However, it is necessary to prepare a current collector for lithium separately, and a process of connecting the current collector for lithium to the negative electrode current collector is also required, so that there is a problem that productivity is low.

  In addition, in the inventions described in Patent Documents 1 to 3, minute lithium powder generated when lithium ions are pre-doped into the negative electrode reaches the positive electrode facing the negative electrode, causing a voltage drop, or deterioration of the negative electrode at high temperatures. Reliability may not be ensured.

  In view of the circumstances as described above, an object of the present invention is to provide an electrochemical device excellent in productivity and reliability and a method for producing the electrochemical device.

In order to achieve the above object, an electrochemical device according to an embodiment of the present invention includes a negative electrode, a positive electrode, a separator, and an electrolytic solution.
The negative electrode is a metal foil, a negative electrode current collector having a first main surface and a second main surface opposite to the first main surface, the first main surface, and the second main surface. A negative electrode active material layer formed on the main surface.
The positive electrode is a metal foil, a positive electrode current collector having a third main surface and a fourth main surface opposite to the third main surface, the third main surface, and the fourth main surface. A positive electrode active material layer formed on the main surface.
The separator insulates the positive electrode and the negative electrode.
The electrolytic solution immerses the positive electrode, the negative electrode, and the separator.
In the electrochemical device, the positive electrode, the negative electrode, and the separator are laminated, and the first main surface and the third main surface are wound inside, the second main surface, and the fourth main surface. Is an electrochemical device wound so as to be wound outside, and the separator separates the positive electrode and the negative electrode,
The first main surface protrudes from the first region facing the positive electrode through the separator and the end of the positive electrode on the outermost winding side, and does not face the positive electrode through the separator. And having an area of
The second main surface has a third region which is a region opposite to the first region, and a fourth region which is a region opposite to the second region,
The fourth region includes an uncoated region in which the negative electrode active material layer is not formed, and metallic lithium is joined to the uncoated region and immersed in the electrolytic solution, whereby the negative electrode active material An electrochemical device in which the layer is pre-doped with lithium ions.

  According to this structure, metallic lithium protrudes from the end part of the positive electrode on the outermost winding side, and is bonded to the fourth region that does not face the positive electrode via the separator. Thereby, even when a minute lithium powder is generated when lithium ions are pre-doped on the negative electrode, the contact of the lithium powder with the positive electrode is suppressed. Therefore, it becomes difficult to produce the malfunction by the influence of the lithium powder which generate | occur | produces in the process of the pre dope to a negative electrode, and it becomes possible to ensure more reliable reliability than the conventional lithium ion capacitor.

  Moreover, the said electrochemical device can utilize the 4th area | region in the 2nd main surface of a negative electrode collector as a metal lithium installation surface. Thereby, in order to pre-dope lithium ions into the negative electrode, a step of separately preparing components such as a current collector for lithium and connecting the components to the negative electrode becomes unnecessary, and thus productivity can be improved. Therefore, according to the present invention, it is possible to provide an electrochemical device excellent in productivity and reliability.

  The uncoated area may be provided in the entire fourth area.

  According to this configuration, metallic lithium can be attached to the entire fourth region of the second main surface of the negative electrode current collector. Thereby, a sufficient amount of lithium ions can be pre-doped in the negative electrode, and the capacity of the capacitor can be increased.

The negative electrode is formed in the first region, the first negative electrode active material layer formed in the third region, and separated from the first negative electrode active material layer in the fourth region. A second negative electrode active material layer formed on the portion,
The uncoated region may be provided between the first negative electrode active material layer and the second negative electrode active material layer.

  By providing the second negative electrode active material layer at the end of the negative electrode current collector, it is possible to prevent the separator from being damaged by the cutting edge of the negative electrode current collector.

  The negative electrode current collector may be made of copper.

  Copper is suitable as a material for the negative electrode current collector because it is strong even when thin and has high flexibility. By crimping copper and metallic lithium, melting of metallic lithium from the interface side due to the electrolyte entering the crimped interface is suppressed, and conduction between the negative electrode current collector and metallic lithium is maintained. Thereby, lithium ion can be appropriately pre-doped to the negative electrode.

  The negative electrode current collector may have a plurality of through holes.

  By forming a through hole in the negative electrode current collector, the efficiency of pre-doping lithium ions into the negative electrode can be improved.

In order to achieve the above object, a method for producing an electrochemical device according to an aspect of the present invention includes:
A negative electrode active material on the first main surface and the second main surface of the negative electrode current collector that is a metal foil and has a first main surface and a second main surface opposite to the first main surface Forming a layer, forming an uncoated region in which the negative electrode active material layer is not provided on the second main surface, and producing a negative electrode;
Bonding metal lithium to the uncoated region,
A positive electrode current collector, which is a metal foil and has a fourth main surface opposite to the third main surface and the third main surface, and is formed on the third main surface and the fourth main surface Preparing a positive electrode having a positive electrode active material layer formed, laminating the positive electrode, the separator and the negative electrode to form a laminate;
The separator is wound so that the first main surface and the third main surface are wound inside, and the second main surface and the fourth main surface are wound outside, and the separator Is a step of forming a storage element separating the positive electrode and the negative electrode, wherein the first main surface is a first region facing the positive electrode with the separator interposed therebetween, and the positive electrode on the outermost winding side. And a second region that does not face the positive electrode through the separator, and the second main surface is a region opposite to the first region, and a third region Forming a power storage element having a fourth region that is a region opposite to the second region, and wherein the uncoated region is provided in the fourth region;
Immersing the electricity storage element in an electrolytic solution, and doping lithium ions into the negative electrode active material layer from the metal lithium.

In the step of manufacturing the negative electrode, a negative electrode current collector that is a metal foil having a first main surface and a second main surface opposite to the first main surface is prepared.
Forming a first negative electrode active material layer on the entire first main surface, forming a plurality of second negative electrode active material layers at a predetermined interval on the second main surface;
The second negative electrode active material layer, the negative electrode current collector, and the first negative electrode active material layer may be cut together.

In the step of manufacturing the negative electrode, a negative electrode current collector that is a metal foil having a first main surface and a second main surface opposite to the first main surface is prepared.
Forming a first negative electrode active material layer on the entire first main surface, forming a plurality of second negative electrode active material layers at a predetermined interval on the second main surface;
The negative electrode current collector and the first negative electrode active material layer may be cut together between the second negative electrode active material layers.

  As described above, according to the present invention, it is possible to provide an electrochemical device excellent in productivity and reliability and a method for manufacturing the electrochemical device.

It is a perspective view which shows the structure of the electrochemical device which concerns on this embodiment. It is a perspective view of the electrical storage element of the embodiment. It is an expanded sectional view of the electrical storage element of the embodiment. It is a schematic diagram which shows the negative electrode before winding of the embodiment. It is a schematic diagram which shows the positive electrode before winding of the embodiment. It is sectional drawing of the electrical storage element of the embodiment. It is a schematic diagram which shows the manufacturing process of the electrochemical device which concerns on the same embodiment. It is a schematic diagram which shows the manufacturing process of the electrochemical device which concerns on the same embodiment. It is a schematic diagram which shows the manufacturing process of the electrochemical device which concerns on the same embodiment. It is a schematic diagram which shows the manufacturing process of the electrochemical device which concerns on the same embodiment. It is a schematic diagram which shows the manufacturing process of the electrochemical device which concerns on the same embodiment. It is a schematic diagram which shows the manufacturing process of the electrochemical device which concerns on the modification of the embodiment. It is sectional drawing of the electrical storage element which concerns on the modification of the embodiment. It is a table | surface which shows the result of the characteristic test of the electrochemical device which concerns on the Example and comparative example of this invention.

  The electrochemical device of the present invention will be described. The electrochemical device according to the present embodiment is an electrochemical device that uses lithium ions for charge transport, such as a lithium ion capacitor.

[Configuration of electrochemical device]
FIG. 1 is a perspective view showing a configuration of an electrochemical device 100 according to the present embodiment. As shown in the figure, the electrochemical device 100 is configured such that a storage element 110 is accommodated in a container 120 (a lid and a terminal are not shown). In the container 120, an electrolytic solution is stored together with the power storage element 110.

  FIG. 2 is a perspective view of the power storage element 110, and FIG. 3 is an enlarged cross-sectional view of the power storage element 110. As shown in FIGS. 2 and 3, the power storage device 110 includes a negative electrode 130, a positive electrode 140, and a separator 150, and a stacked body in which these are stacked is wound around a winding core C. . In the following drawings, the X, Y, and Z directions are three directions orthogonal to each other. Note that the wound core C is not necessarily provided.

  As shown in FIG. 2, the stacking order of the negative electrode 130, the positive electrode 140, and the separator 150 constituting the power storage element 110 is the separator 150, the negative electrode 130, the separator 150, and the positive electrode toward the wound core C (from the wound outer side). The order is 140. In addition, the storage element 110 has a negative electrode terminal 131 and a positive electrode terminal 141 as shown in FIG. The negative electrode terminal 131 is connected to the negative electrode, and the positive electrode terminal 141 is connected to the positive electrode, and as shown in FIG.

  As illustrated in FIG. 3, the negative electrode 130 includes a negative electrode current collector 132 and a negative electrode active material layer 133. The negative electrode current collector 132 is made of a conductive material and can be a metal foil such as a copper foil. The negative electrode current collector 132 may be a metal foil whose surface is chemically or mechanically roughened or a metal foil in which a through hole is formed. In this embodiment, a through hole is typically formed. Metal foil is used.

  The negative electrode active material layer 133 is formed on the negative electrode current collector 132. The material of the negative electrode active material layer 133 may be a material in which the negative electrode active material is mixed with a binder resin, and may further include a conductive additive. The negative electrode active material is a material that can adsorb lithium ions in the electrolytic solution, and for example, a carbon-based material such as non-graphitizable carbon (hard carbon), graphite, or soft carbon can be used.

  The binder resin is a synthetic resin that joins the negative electrode active material. For example, styrene butadiene rubber, polyethylene, polypropylene, polyethylene terephthalate, aromatic polyamide, carboxymethyl cellulose, fluorine rubber, polyvinylidene fluoride, isoprene rubber, butadiene rubber, and ethylene. Propylene rubber or the like may be used.

  The conductive auxiliary agent is a particle made of a conductive material, and improves the conductivity between the negative electrode active materials. Examples of the conductive assistant include carbon materials such as graphite and carbon black. These may be single and multiple types may be mixed. The conductive auxiliary agent may be a metal material or a conductive polymer as long as it is a conductive material.

  4A and 4B are schematic views showing the negative electrode 130 before winding, in which FIG. 4A is a side view and FIG. 4B is a view seen from the Z direction. As shown in FIG. 4A, the negative electrode 130 according to this embodiment has a negative electrode active material layer 133 formed on both the first main surface 132 a and the second main surface 132 b of the negative electrode current collector 132.

  Here, as shown in FIG. 4A, the negative electrode 130 is provided with an uncoated region 130a and a peeling region 130b where the negative electrode active material layer 133 is not formed on the second main surface 132b. The uncoated region 130a may be provided on the first main surface 132a.

  As shown in FIG. 4B, metallic lithium M serving as a lithium ion supply source is joined to the negative electrode current collector 132 in the uncoated region 130a. The shape of the metal lithium M is not particularly limited, but a foil shape is preferable in order to reduce the thickness of the power storage element 110. The amount of metallic lithium M can be adjusted so that the negative electrode active material layer 133 can be doped in lithium ion pre-doping described later.

  As shown in FIG. 4A, the negative electrode terminal 131 is connected to the negative electrode current collector 132 in the peeling region 130 b and is drawn out of the negative electrode 130. Further, the peeling region 130b according to the present embodiment is sealed with a tape T as shown in FIG. 4A so that the negative electrode current collector 132 in the peeling region 130b is not exposed. The kind of tape T is not specifically limited, What has heat resistance and the solvent resistance with respect to the solvent of electrolyte solution is employ | adopted suitably. The negative terminal 131 is, for example, a copper terminal.

  As illustrated in FIG. 3, the positive electrode 140 includes a positive electrode current collector 142 and a positive electrode active material layer 143. The positive electrode current collector 142 is made of a conductive material and can be a metal foil such as an aluminum foil. The positive electrode current collector 142 may be a metal foil whose surface is chemically or mechanically roughened, or a metal foil in which a through hole is formed.

  The positive electrode active material layer 143 is formed on the positive electrode current collector 142. The material of the positive electrode active material layer 143 can be a mixture of the positive electrode active material and the binder resin, and may further include a conductive additive. The positive electrode active material is a material capable of adsorbing lithium ions and anions in the electrolytic solution, and for example, activated carbon or polyacene carbide can be used.

  The binder resin is a synthetic resin that joins the positive electrode active material. For example, styrene butadiene rubber, polyethylene, polypropylene, polyethylene terephthalate, aromatic polyamide, carboxymethyl cellulose, fluorine rubber, polyvinylidene fluoride, isoprene rubber, butadiene rubber, and ethylene. Propylene rubber or the like may be used.

  The conductive auxiliary agent is a particle made of a conductive material, and improves the conductivity between the positive electrode active materials. Examples of the conductive assistant include carbon materials such as graphite and carbon black. These may be single and multiple types may be mixed. The conductive auxiliary agent may be a metal material or a conductive polymer as long as it is a conductive material.

  FIG. 5 is a schematic view showing the positive electrode 140 before winding, in which FIG. 5 (a) is a side view and FIG. 5 (b) is a plan view. As shown in FIG. 5A, the positive electrode 140 according to this embodiment includes a positive electrode active material layer 143 formed on both surfaces of the third main surface 142 a and the fourth main surface 142 b of the positive electrode current collector 142. A peeling region 140a where the positive electrode active material layer 143 is not formed is provided on the main surface 142a.

  Here, as shown in FIG. 5, a positive electrode terminal 141 is connected to the positive electrode current collector 142 in the peeling region 140 a and is drawn out of the positive electrode 140. In the positive electrode 140, the peeling region 140a where the positive electrode terminal 141 is disposed may be formed on the fourth main surface 142b. Further, the peeling region 140a may be sealed with a tape or the like. The positive terminal 141 is, for example, an aluminum terminal.

  The separator 150 insulates the negative electrode 130 from the positive electrode 140 and includes a first separator 151 and a second separator 152 as shown in FIG.

  The 1st separator 151 and the 2nd separator 152 permeate | transmit the ion contained in the electrolyte solution mentioned later, separating the negative electrode 130 and the positive electrode 140. FIG. Specifically, the first separator 151 and the second separator 152 can be woven fabric, non-woven fabric, synthetic resin microporous membrane, or the like. Further, the first separator 151 and the second separator 152 may be a single continuous separator.

  FIG. 6 is a cross-sectional view of the storage element 110 (the negative electrode terminal 131 and the positive electrode terminal 141 are not shown). As shown in FIG. 6, the power storage device 110 according to the present embodiment includes a negative electrode 130 and a positive electrode 140 that are stacked via a first separator 151 and a second separator 152 and wound. Specifically, the first main surface 132a of the negative electrode current collector 132 and the third main surface 142a of the positive electrode current collector 142 are wound inside, and the second main surface 132b of the negative electrode current collector 132 and the positive electrode current collector are arranged. The fourth main surface 142b of 142 is configured to be on the outer side of the winding.

  Here, the electricity storage element 110 has a configuration in which the electrode on the outermost winding (outermost periphery) is the negative electrode 130. As shown in FIG. 6, the end of the outermost negative electrode 130 protrudes beyond the end of the outermost positive electrode 140, and the second main surface 132 b of the outermost negative current collector 132. Is provided with an uncoated region 130a.

  Further, as shown in FIG. 6, the first main surface 132a of the negative electrode current collector 132 is most wound with the first region 132c facing the positive electrode 140 (positive electrode active material layer 143) with the first separator 151 interposed therebetween. The second region 132d protrudes from the end of the outer positive electrode 140 and does not face the positive electrode 140 (positive electrode active material layer 143) with the first separator 151 interposed therebetween. As shown in FIG. 6, the second main surface 132b has a third region 132e that is a region opposite to the first region 132c and a fourth region 132f that is a region opposite to the second region 132d.

  As shown in FIG. 6, the fourth region 132f includes an uncoated region 130a. The uncoated region 130a according to the present embodiment is provided in a part of the fourth region 132f as shown in FIG. The uncoated region 130a may be provided in the entire fourth region 132f.

  The container 120 accommodates the power storage element 110. The upper surface and the lower surface of the container 120 can be closed by a lid (not shown). The material of the container 120 is not specifically limited, For example, it can consist of a metal which has aluminum, titanium, nickel, iron as a main component, stainless steel, etc.

The electrochemical device 100 is configured as described above. The electrolytic solution accommodated in the container 120 together with the power storage element 110 can be a liquid containing lithium ions and anions, for example, a liquid in which LiBF ₄ or LiPF ₆ is dissolved in a solvent (such as carbonate) as an electrolyte.

[Effects of electrochemical devices]
Next, the effect of the electrochemical device 100 will be described. In the electrochemical device 100 according to this embodiment, when the power storage element 110 to which the metallic lithium M is bonded contacts the electrolytic solution, the metallic lithium M is oxidized and dissolved, and the lithium ions (Li +) and electrons (e− ) Occurs. As a result, lithium ions diffuse into the electrolytic solution, are doped into the negative electrode active material contained in the negative electrode active material layer 133, and electrons flow to the negative electrode 130. By aging in this state, the negative electrode 130 (negative electrode active material layer 133) is pre-doped with lithium ions.

  Here, in the conventional general lithium ion capacitor, as a method of pre-doping lithium ions into the negative electrode, a method of immersing a storage element in which a lithium current collector with metal lithium attached is connected to the negative electrode in an electrolytic solution Is widely practiced. However, in such a method, it is necessary to prepare a current collector for lithium separately, and a step of connecting the current collector for lithium to the negative electrode current collector is required, so that there is a problem that productivity is low.

  In addition, in the lithium ion capacitor as described above, when lithium ions are pre-doped into the negative electrode, there is a possibility that defects such as voltage drop occur due to the minute lithium powder generated in the pre-doping process, and the reliability of the capacitor may not be ensured. .

  On the other hand, in the electrochemical device 100 according to the present embodiment, as shown in FIG. 6, the metallic lithium M serving as a lithium ion supply source protrudes from the end of the outermost positive electrode 140, and the separator 150 It is joined to the fourth region 132 f on the outermost winding side that does not face the positive electrode 140 via the electrode.

  As a result, even when fine lithium powder is generated when the negative electrode 130 is pre-doped with lithium ions, the contact of the lithium powder with the positive electrode 140 is suppressed. Therefore, it is difficult for problems due to the influence of the lithium powder generated in the pre-doping process on the negative electrode 130 to occur, and it is possible to secure more stable reliability than the conventional lithium ion capacitors.

  In particular, the fourth region 132f on the outermost winding side protrudes from the end portion of the positive electrode 140 on the outermost winding side and does not face the positive electrode 140 with the separator 150 interposed therebetween. As a result, the metallic lithium M can be disposed without reducing the capacity of the power storage element 110.

  Further, in the electrochemical device 100 according to the present embodiment, the negative electrode 130 includes the first negative electrode active material layer 133a formed in the third region 132e of the second main surface 132b and the fourth region 132f, as shown in FIG. And a second negative electrode active material layer 133b formed at the end of the negative electrode current collector 132 and spaced from the first negative electrode active material layer 133a. Here, the uncoated region 130a is provided between the first negative electrode active material layer 133a and the second negative electrode active material layer 133b, as shown in FIG.

  Thereby, even if the cutting edge of the negative electrode current collector 132 becomes sharp, the second negative electrode active material layer 133b is on the cutting edge of the negative electrode current collector 132 as shown in FIG. It becomes possible to prevent the second separator 152 from being damaged.

  Further, since the negative electrode 130 is pre-doped with lithium ions, it is not necessary to separately prepare a lithium current collector as in the conventional lithium ion capacitor, and the lithium current collector is connected to the negative electrode current collector 132. Productivity can also be ensured because no process is required.

[Method of manufacturing electrochemical device]
A method for manufacturing the electrochemical device 100 according to this embodiment will be described. In addition, the manufacturing method shown below is an example, and the electrochemical device 100 can also be manufactured by a manufacturing method different from the manufacturing method shown below. 7 to 11 are schematic diagrams showing the manufacturing process of the electrochemical device 100. FIG.

  FIG. 7A shows a metal foil 232 in which a through-hole serving as a base of the negative electrode current collector 132 is formed. The metal foil 232 is, for example, a copper foil. Although the thickness of the metal foil 232 is not specifically limited, For example, it can be set to several tens of micrometers-several hundreds of micrometers.

  Next, a negative electrode paste containing a negative electrode active material, a conductive additive, a binder, and the like is applied to the back surface 232b of the metal foil 232, and is dried or cured. Thereby, as shown in FIG. 7B, the negative electrode active material layer 233 is formed on the back surface 232 b of the metal foil 232.

  Subsequently, as shown in FIG. 7C, a masking tape MT is attached to the surface 232a of the metal foil 232 at equal intervals along the X direction. Then, the negative electrode paste is applied again to the surface 232a of the metal foil 232 to which the masking tape MT is attached, dried or cured, and the negative electrode is applied to the surface 232a of the metal foil 232 as shown in FIG. An active material layer 233 is formed.

  Next, the negative electrode active material layer 233 formed on the surface 232a of the metal foil 232 is partially removed by peeling the masking tape MT so that the metal foil 232 is exposed as shown in FIG. 8B. An electrode layer 230 in which a plurality of peeling regions 230a are formed is obtained. Thereby, as shown in the figure, a plurality of negative electrode active material layers 233 are formed on the surface 232a of the metal foil 232 at a predetermined interval. The negative electrode active material layer 233 may be formed using a method other than masking.

  Next, as shown in FIG. 8C, the negative electrode active material layer 233 formed on the front surface 232a of the metal foil 232, the negative electrode active material layer 233 formed on the entire back surface 232b, and the metal foil 232 are cut together. (Cutting along the dotted line R1 shown in FIG. 8C). As a result, as shown in FIG. 9A, an electrode layer 230 in which a peeling region 230 a is formed on the surface 232 a of the metal foil 232 is obtained.

  Next, the negative electrode active material layer 233 formed on the surface 232a of the metal foil 232 is partially peeled to form a peeling region 230b where the metal foil 232 is exposed as shown in FIG. 9B. Then, as shown in the figure, the negative electrode terminal 231 is connected to the metal foil 232 in the peeling region 230b, and the peeling region 230b is sealed with the tape T to obtain the negative electrode 130.

  Subsequently, as illustrated in FIG. 10A, a metal foil 242 in which a through hole that is a base of the positive electrode current collector 142 is formed is prepared. The metal foil 242 is, for example, an aluminum foil. The thickness of the metal foil 242 is not particularly limited, but can be, for example, several tens of μm to several hundreds of μm.

  Next, a positive electrode paste containing a positive electrode active material, a conductive additive, a binder, and the like is applied to the front surface 242a and the back surface 242b of the metal foil 242, and dried or cured. As a result, as shown in FIG. 10B, an electrode layer 240 in which the positive electrode active material layer 243 is formed on the metal foil 242 is obtained.

  Next, the electrode layer 240 is cut, and the positive electrode active material layer 243 formed on one of the front surface 242a and the back surface 242b of the metal foil 242 is partially peeled, and as shown in FIG. A peeling region 240a where the metal foil 242 is exposed is formed. And as shown in the figure, the positive electrode terminal 241 is connected to the metal foil 242 in the peeling area 240a, and the positive electrode 140 is obtained.

  Subsequently, the negative electrode 130, the positive electrode 140, the first separator 251, and the second separator 252 are stacked to obtain a stacked body 310 as illustrated in FIGS. 11A and 11B. At this time, as shown in FIG. 11A, the negative electrode 130 is the winding inner side and the positive electrode 140 is the winding outer side, and the end of the metal foil 232 opposite to the end on the peeling region 230a side is the winding core C. The laminated body 310 is arranged so as to be on the side. In addition, FIG.11 (b) is a top view of the laminated body 310 of Fig.11 (a). Moreover, the laminated body 310 is not limited to the structure shown in FIG.

  Next, as shown in FIG. 11 (c), the end of the negative electrode 130 is sandwiched between the winding cores C, and the laminate 310 is rotated clockwise around the winding core C so that the peeling region 230a is on the outermost winding side. Whip up and spin.

  Thus, a wound body in which the back surface 232b of the metal foil 232 and the surface 242a of the metal foil 242 are wound inside, and the surface 232a of the metal foil 232 and the back surface 242b of the metal foil 242 are wound outside (see FIGS. 2 and 6). )

  Subsequently, metallic lithium M is joined to the peeling region 230a disposed on the outermost winding side of the wound body obtained by the above-described process (see FIG. 6), and the power storage element 110 is obtained. Next, the storage element 110 to which the metallic lithium M is bonded is accommodated in the container 120 containing the electrolytic solution and sealed. Thus, lithium ions are doped from the metal lithium M into the negative electrode active material layer 233.

  As described above, the electrochemical device 100 can be manufactured. Note that the negative terminal 231 corresponds to the negative terminal 131, and the positive terminal 241 corresponds to the positive terminal 141. Further, the peeling area 230a corresponds to the uncoated area 130a, the peeling area 230b corresponds to the peeling area 130b, and the peeling area 240a corresponds to the peeling area 140a.

  Further, the metal foil 232 corresponds to the negative electrode current collector 132, the metal foil 242 corresponds to the positive electrode current collector 142, the negative electrode active material layer 233 corresponds to the negative electrode active material layer 133, and the positive electrode active material layer 243 corresponds to the positive electrode active material layer 143. Corresponding to

  In addition, the front surfaces 232a and 242a correspond to the second main surface 132b and the third main surface 142a, respectively, and the back surfaces 232b and 242b correspond to the first main surface 132a and the fourth main surface 142b, respectively. The first separator 251 corresponds to the first separator 151, and the second separator 252 corresponds to the second separator 152.

[Modification]
The configuration and manufacturing method of the electrochemical device 100 are not limited to those described above. FIG. 12 is a schematic diagram illustrating a manufacturing process of the electrochemical device 100 according to the modification, and FIG. 13 is a cross-sectional view of the power storage element 110 according to the modification.

  In the above embodiment, when the electrode layer 230 is cut, the negative electrode active material layer 233 formed on the front surface 232a of the metal foil 232, the negative electrode active material layer 233 formed on the entire back surface 232b, and the metal foil 232 are separated. However, the present invention is not limited to this, and as shown in FIG. 12, the entire metal foil 232 and the back surface 232b are formed between the negative electrode active material layers 233 formed on the front surface 232a of the metal foil 232 with a predetermined interval. The negative electrode active material layer 233 formed in the above may be cut together (may be cut along a dotted line R2 shown in FIG. 12).

  By cutting the electrode layer 230 in this manner, the negative electrode 130 has a configuration in which an uncoated region 130a is provided in the entire fourth region 132f, as shown in FIG. As a result, the metallic lithium M can be attached to the entire outermost fourth region 132f of the second main surface 132b, so that a sufficient amount of lithium ions can be pre-doped into the negative electrode 130, and the capacitance of the capacitor can be increased. Can be achieved.

  Electrochemical devices according to Examples and Comparative Examples of the present invention were produced and subjected to characteristic tests.

[Production of electrochemical devices]
Example 1
The electrochemical device was produced as follows. First, a non-graphitizable carbon, a conductive aid, a binder and a thickener were mixed and kneaded in water to prepare a negative electrode paste. Then, a through-hole having a diameter of 100 μm formed by etching has a ratio of 30% with respect to the area of the main surface, and a copper foil having a thickness of 15 μm is used as a negative electrode current collector. The negative electrode active material layer having a thickness of 50 μm was formed on the back surface of the copper foil by applying and drying for 12 hours under a reduced pressure environment of 180 ° C. and 1 kPa or less (see FIG. 7B).

  Next, a masking tape having a width of 30 mm was attached to the surface of the copper foil at intervals of 210 mm along the longitudinal direction of the copper foil. Next, a negative electrode paste was applied to the surface of the copper foil to which the masking tape was affixed, and dried in an 80 ° C. atmosphere. After drying, the masking tape was peeled off to form an electrode layer having a peeling region where the negative electrode active material layer was not formed on the surface of the copper foil (see FIG. 8B). The electrode having the peeling region was dried at 180 ° C. under a reduced pressure environment of 1 kPa or less for 12 hours.

  Subsequently, the electrode layer was cut, and the negative electrode active material layer formed on the surface of the copper foil was partially peeled to form a peeled portion. And the copper terminal was caulked to the said peeling part, and the peeling part was sealed with the tape with the copper terminal, and the negative electrode 27 mm in width and 240 mm in length was produced (refer FIG.9 (b)).

  Next, a positive electrode paste was prepared by mixing activated carbon, a conductive additive, a binder and a thickener and kneading them in water. Then, a positive electrode paste is applied to both the front and back surfaces of an aluminum foil having a thickness of 30 μm to which gas permeability is imparted by forming a through hole by etching, and the pressure is reduced to 180 ° C. and 1 kPa or less. The electrode layer which has a positive electrode active material layer about 100 micrometers in thickness on both front and back was produced by drying for 12 hours below (refer FIG.10 (b)).

  Subsequently, the electrode layer was cut, and one of the positive electrode active material layers formed on both the front and back surfaces of the aluminum foil was partially peeled to form a peeled portion. Then, a positive electrode having a width of 24 mm and a length of 170 mm was produced by caulking an aluminum terminal to the peeled portion (see FIG. 10C).

  Next, a cellulose separator having a density of 45% and a thickness of 35 μm was cut into a uniform width of 30 mm to produce a separator. In addition, the drying conditions at the time of producing the separator were 12 hours under a reduced pressure environment of 160 ° C. and 1 kPa or less.

  Next, after laminating the positive electrode, the negative electrode, and the separator obtained above to obtain a laminate, this laminate was wound so that the back surface of the copper foil was wound inside and the surface was wound outside ( (Refer FIG.11 (c)). Thereby, the winding body by which the peeling area | region currently formed in the surface of copper foil was arrange | positioned at the winding outermost side was obtained (refer FIG. 6).

  Subsequently, metallic lithium having a thickness of 0.1 mm, a width of 25 mm, and a length of 25 mm was joined to the peeled region of the wound body obtained above. Next, the separators were fixed with a tape, and rubber for sealing was fitted into the aluminum terminal and the copper terminal to obtain a power storage element.

Next, the electrochemical device according to Example 1 was manufactured by inserting and sealing the above electricity storage element into an aluminum case having an opening diameter of 12.5 mm in which the electrolytic solution was accommodated. As the electrolytic solution, a propylene carbonate solution (1 mol / L) having LiPF ₆ as a solute was employed.

  Subsequently, electrochemical devices according to Examples 2 and 3 were produced.

  The electrochemical device according to Example 2 was manufactured in the same manner as in Example 1 except that the length of the negative electrode was increased by 10 mm and the amount of metallic lithium was increased by an amount corresponding to the increase in the amount of the negative electrode active material layer from Example 1. .

  The electrochemical device according to Example 3 was manufactured in the same manner as in Example 1 except that the length of the negative electrode was increased by 20 mm and the amount of metallic lithium was increased by an amount corresponding to the increase in the amount of the negative electrode active material layer from Example 1. .

(Comparative example)
Subsequently, the electrochemical device which concerns on Comparative Examples 1-3 was produced. The electrochemical device according to Comparative Example 1 was manufactured in the same manner as the electrochemical device according to Example 1 except that lithium metal was inserted between the negative electrode active material layer and the separator.

  The electrochemical device according to Comparative Example 2 was prepared in the same manner as in Example 1 except that the negative electrode active material layer formed on the negative electrode copper foil not opposed to the positive electrode via the separator was removed.

  The electrochemical device according to Comparative Example 3 is the same as Example 1 except that the peeling region where the metallic lithium is disposed is provided on the back surface of the negative electrode copper foil facing the outermost positive electrode via the separator. Produced. Here, the doping amount of lithium metal was determined according to the amount of the negative electrode active material layer.

[Characteristic evaluation]
Next, 20 electrochemical devices according to Examples and Comparative Examples were prepared, and the characteristics of each device stored for 1 week in a 60 ° C. environment were examined. Specifically, the presence or absence of a voltage drop after the charge of each device was stored, the presence or absence of a voltage drop after charge / discharge, and the remaining metal lithium were examined. Furthermore, five electrochemical devices according to Examples and Comparative Examples were prepared, and the rate of change in internal resistance of each device was measured. FIG. 14 is a table showing the results. Note that “after application of 3.8 V at 85 ° C.” described in FIG. 14 is an average value of the rate of change of the internal resistance when the initial internal resistance obtained from each device is 100.

  As for the presence or absence of voltage drop, charging voltage = 3.8V, charging current = 2.0A, CV (constant voltage) time = 10 minutes (2.0A is passed until the voltage reaches 3.8V and reaches 3.8V) Then, 3.8 V was held for 10 minutes), and each device was measured by charging and discharging 500 times under the condition of a discharge condition of 2.2 V cutoff. The rate of change of internal resistance was measured by applying a voltage of 3.8 V to each device for 1000 hours in an 85 ° C. environment and then returning each device to room temperature. The rate of change in internal resistance in this example was calculated according to the measurement method for lithium ion capacitors in RCEI 2462 of JEITA (Electronic Information Technology Industries Association).

  As shown in FIG. 14, the electrochemical devices according to Examples 1 to 3 were not confirmed to have any remaining metallic lithium in all of the 20 devices, and the entire amount was pre-doped. In addition, there was no device with a reduced voltage, and no significant fluctuation in internal resistance was confirmed.

  In contrast, the electrochemical device according to Comparative Example 1 was confirmed to have many devices in which lithium metal remained as shown in FIG. In addition, as shown in the figure, the electrochemical device according to Comparative Example 2 was confirmed to have a device in which the voltage decreased after charge was stored and after charge / discharge, and a large fluctuation in internal resistance was also confirmed. .

  Further, as shown in FIG. 14, the electrochemical device according to Comparative Example 3 did not confirm the remaining of the lithium metal and the decrease in voltage, but as in Comparative Example 2, a large variation in internal resistance was confirmed. . From the above, it can be said that the electrochemical device according to the above embodiment has a structure in which pre-doping of metallic lithium proceeds well, and characteristic deterioration such as a decrease in voltage and a large fluctuation in internal resistance due to a high temperature environment hardly occurs. .

  As mentioned above, although embodiment of this invention was described, this invention is not limited only to the above-mentioned embodiment, Of course, a various change is added.

DESCRIPTION OF SYMBOLS 100 ... Electrochemical device 110 ... Power storage element 120 ... Container 130 ... Negative electrode 130a ... Uncoated area 131 ... Negative electrode terminal 132 ... Negative electrode current collector 132a ... First main Surface 132b ... Second main surface 132c ... First region 132d ... Second region 132e ... Third region 132f ... Fourth region 133 ... Negative electrode active material layer 140 ... Positive electrode 141 ... Positive electrode Terminal 142 ... Positive electrode current collector 142a ··· Third main surface 142b · · Fourth main surface 143 · · · Positive electrode active material layer 151 ··· First separator 152 ··· Second separator M ···・ Metal lithium

Claims (8)

A negative electrode current collector that is a metal foil and has a second main surface opposite to the first main surface and the first main surface, and is formed on the first main surface and the second main surface A negative electrode having a negative electrode active material layer formed;
A positive electrode current collector, which is a metal foil and has a fourth main surface opposite to the third main surface and the third main surface, and formed on the third main surface and the fourth main surface A positive electrode having a positive electrode active material layer formed;
A separator for insulating the positive electrode and the negative electrode;
An electrolyte for immersing the positive electrode, the negative electrode, and the separator;
The positive electrode, the negative electrode, and the separator are laminated, and the first main surface and the third main surface are wound inside, and the second main surface and the fourth main surface are wound outside. And an electrochemical device in which the separator separates the positive electrode and the negative electrode,
The first main surface protrudes from the first region facing the positive electrode through the separator and the end of the positive electrode on the outermost winding side, and does not face the positive electrode through the separator. And having an area of
The second main surface has a third region which is a region opposite to the first region, and a fourth region which is a region opposite to the second region,
The fourth region includes an uncoated region in which the negative electrode active material layer is not formed, and metallic lithium is joined to the uncoated region and immersed in the electrolytic solution, whereby the negative electrode active material An electrochemical device in which the layer is pre-doped with lithium ions. The electrochemical device according to claim 1,
The uncoated region is an electrochemical device provided in the entire fourth region. The electrochemical device according to claim 1,
The negative electrode includes a first negative electrode active material layer formed in the third region and a fourth region formed in the fourth region, spaced from the first negative electrode active material, and an end of the negative electrode current collector. And a second negative electrode active material layer formed on
The uncoated region is an electrochemical device provided between the first negative electrode active material layer and the second negative electrode active material layer. The electrochemical device according to any one of claims 1 to 3,
The negative electrode current collector is an electrochemical device made of copper. The electrochemical device according to any one of claims 1 to 4,
The negative electrode current collector is an electrochemical device having a plurality of through holes. A negative electrode active material on the first main surface and the second main surface of a negative electrode current collector that is a metal foil and has a first main surface and a second main surface opposite to the first main surface Forming a layer, forming an uncoated region in which the negative electrode active material layer is not provided on the second main surface, and producing a negative electrode;
Bonding metal lithium to the uncoated region;
A positive electrode current collector, which is a metal foil and has a fourth main surface opposite to the third main surface and the third main surface, and formed on the third main surface and the fourth main surface Preparing a positive electrode having a positive electrode active material layer formed, and laminating the positive electrode, the separator and the negative electrode to form a laminate;
The separator is wound so that the first main surface and the third main surface are wound inside, and the second main surface and the fourth main surface are wound outside, the separator Is a step of forming a storage element separating the positive electrode and the negative electrode, wherein the first main surface is a first region facing the positive electrode with the separator interposed therebetween, and the positive electrode on the outermost winding side. And a second region that does not face the positive electrode through the separator, and the second main surface is a region opposite to the first region, and a third region Forming a power storage element having a fourth region which is a region opposite to the second region, and wherein the uncoated region is provided in the fourth region;
A step of immersing the electricity storage element in an electrolytic solution and doping lithium ions into the negative electrode active material layer from the metal lithium. A method for producing an electrochemical device according to claim 6,
In the step of producing the negative electrode, a negative electrode current collector that is a metal foil having a first main surface and a second main surface opposite to the first main surface is prepared,
Forming a first negative electrode active material layer on the entire first main surface, forming a plurality of second negative electrode active material layers on the second main surface at a predetermined interval;
A method for producing an electrochemical device, wherein the second negative electrode active material layer, the negative electrode current collector, and the first negative electrode active material layer are cut together. A method for producing an electrochemical device according to claim 6,
In the step of producing the negative electrode, a negative electrode current collector that is a metal foil having a first main surface and a second main surface opposite to the first main surface is prepared,
Forming a first negative electrode active material layer on the entire first main surface, forming a plurality of second negative electrode active material layers on the second main surface at a predetermined interval;
A method for producing an electrochemical device, wherein the negative electrode current collector and the first negative electrode active material layer are cut together between second negative electrode active material layers.

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