JP6684034B2 - Electrochemical device and method for manufacturing electrochemical device - Google Patents

Description

  TECHNICAL FIELD The present invention relates to an electrochemical device having an electricity storage element formed 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 been attracting attention as main power sources or auxiliary power sources for clean energy storage systems such as solar power and wind power generation, and 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 using a material capable of occluding lithium in the negative electrode has a higher capacity than an electric double layer capacitor and has a longer life than a battery, and therefore replacement applications from the battery are spreading.

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

  Further, Patent Document 2 discloses a lithium-ion power storage element in which an active material layer is laminated on a negative electrode current collector, and a region where the active material layer is not laminated is formed on the negative electrode current collector, and lithium is formed in the region. Are placed and pre-doped.

  Further, in Patent Document 3, 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 generated without a problem such as a short circuit. A lithium ion capacitor is disclosed that can be doped into the negative electrode.

JP, 2011-139006, A JP, 2010-232565, A JP, 2009-59732, A

  In the electrochemical device that requires pre-doping of lithium ions as described above, the method of arranging the lithium source is to attach lithium to the lithium current collector and connect the lithium current collector to the negative electrode current collector. is there. However, since it is necessary to separately prepare a lithium current collector and a step of connecting the lithium current collector to the negative electrode current collector is also required, there is a problem of low productivity.

  Further, in the inventions described in Patent Documents 1 to 3, fine lithium powder generated when pre-doping lithium ions into the negative electrode reaches the positive electrode facing the negative electrode, and a voltage drop occurs, so that reliability may not be ensured. There is also.

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

To achieve the above object, an electrochemical device according to an aspect 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. And 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. And a positive electrode active material layer formed on the main surface.
The separator insulates the positive electrode and the negative electrode.
The positive electrode, the negative electrode, and the separator are dipped in the electrolytic solution.
In the electrochemical device, the positive electrode, the negative electrode, and the separator are laminated, the first main surface and the third main surface are wound inside, and the second main surface and the fourth main surface are Is an electrochemical device in which the separator is wound so that it is on the outside, and the separator separates the positive electrode and the negative electrode,
The first main surface faces the positive electrode via the separator,
The second main surface has a first region facing the positive electrode via the separator, and a second region that is the outermost wound side and does not face the positive electrode.
The second region includes a first uncoated region in which the negative electrode active material layer is not formed, and metallic lithium is bonded to the first uncoated region and immersed in the electrolytic solution. The electrochemical device in which the negative electrode active material layer is pre-doped with lithium ions.

  According to this configuration, metallic lithium is bonded to the outermost second outermost winding main surface that does not face the positive electrode via the separator. Thereby, even if minute lithium powder is generated when the negative electrode is pre-doped with lithium ions, the contact of the lithium powder with the positive electrode is suppressed. Therefore, a defect due to the influence of lithium powder generated in the process of pre-doping the negative electrode is less likely to occur, and stable reliability can be secured as compared with the conventional lithium ion capacitors.

  Further, in the above electrochemical device, the second region on the second main surface of the negative electrode current collector can be used as a mounting surface for metallic lithium. This eliminates the step of separately preparing a component such as a current collector for lithium and preliminarily doping the negative electrode with lithium ions and connecting the component to the negative electrode, so that the productivity can be improved. Therefore, according to the present invention, it becomes possible to provide an electrochemical device having excellent productivity and reliability.

  The first uncoated area may be provided over the entire second area.

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

The negative electrode is formed on the first negative electrode active material layer formed on the first region and on the second region, and is separated from the first negative electrode active material layer, and the end of the negative electrode current collector is formed. A second negative electrode active material layer formed in
The first 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 portion of the negative electrode current collector, it is possible to prevent the separator from being damaged by the cut side of the negative electrode current collector.

  The second main surface may include a second uncoated region where the negative electrode active material layer is not provided at the end of the negative electrode current collector on the innermost winding side.

  As a result, a part of the outermost wound negative electrode active material layer that is not involved in charging / discharging of the capacitor is removed, and the storage element can be made compact.

  The negative electrode current collector may be made of copper.

  Copper is suitable as a material for the negative electrode current collector because it has high strength and flexibility even if it is thin. By crimping copper and metallic lithium, the melting of metallic lithium from the interface side due to the entry of the electrolytic solution into the crimped interface is suppressed, and conduction between the negative electrode current collector and metallic lithium is maintained. Thereby, the lithium ions can be appropriately pre-doped into the negative electrode.

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

  By forming the through holes 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 manufacturing an electrochemical device according to an aspect of the present invention is
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. A step of forming a layer and forming an uncoated region in which the negative electrode active material layer is not provided on the second main surface to produce a negative electrode;
A step of joining metallic lithium to the uncoated region,
A positive electrode current collector that is a metal foil and has a third main surface and a fourth main surface opposite to the third main surface, and formed on the third main surface and the fourth main surface. A step of preparing a positive electrode having a positive electrode active material layer is formed, and forming a laminate by laminating the positive electrode, the separator and the negative electrode,
The laminate 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 wound. Is a step of forming a power storage element that separates the positive electrode and the negative electrode, the first main surface faces the positive electrode through the separator, and the second main surface through the separator. A power storage element that has a first region facing the positive electrode and a second region that is the outermost wound side and does not face the positive electrode, and the uncoated region is provided in the second region. A step of forming
A step of immersing the power storage element in an electrolytic solution to dope the negative electrode active material layer with lithium ions from the metallic lithium.

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,
A first negative electrode active material layer is formed on the entire first main surface, and a plurality of second negative electrode active material layers are formed on the second main surface at predetermined intervals.
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.

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,
A first negative electrode active material layer is formed on the entire first main surface, and a plurality of second negative electrode active material layers are formed on the second main surface at predetermined intervals.
The second negative electrode active material layer, the negative electrode current collector, and the first negative electrode active material layer may be cut together.

  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 showing the composition of the electrochemical device concerning this embodiment. It is a perspective view of the electrical storage element of the same embodiment. It is an expanded sectional view of the electric storage element of the same embodiment. It is a schematic diagram which shows the negative electrode before winding of the same embodiment. It is a schematic diagram which shows the positive electrode before winding of the same embodiment. It is sectional drawing of the electrical storage element of 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 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 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 such as a lithium ion capacitor that uses lithium ions for transporting electric charges.

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

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

  As shown in FIG. 2, the negative electrode 130, the positive electrode 140, and the separator 150 that form the power storage element 110 are stacked in the order from the winding core C side (from the winding outer side) to the separator 150, the negative electrode 130, the separator 150, and the positive electrode. The order is 140. In addition, the power 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 shown in FIG. 3, the negative electrode 130 has 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 may 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 having a through hole formed therein. In the present embodiment, the through hole is typically formed. Adopted metal foil.

  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 auxiliary material. The negative electrode active material is a material capable of adsorbing lithium ions in the electrolytic solution, and for example, a carbon 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, and includes, 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 conduction aid is particles made of a conductive material and improves the conductivity between the negative electrode active materials. Examples of the conductive aid include carbon materials such as graphite and carbon black. These may be used alone or as a mixture of plural kinds. The conductive additive may be a metal material, a conductive polymer, or the like as long as it has conductivity.

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

  Here, in the negative electrode 130, as shown in FIG. 4A, the first and second uncoated regions 130a and 130b in which the negative electrode active material layer 133 is not formed on the second main surface 132b, and the peeled region 130c. Is provided.

  As shown in FIG. 4B, metallic lithium M serving as a supply source of lithium ions is bonded to the negative electrode current collector 132 in the first uncoated region 130a. The shape of the metallic lithium M is not particularly limited, but a foil shape is preferable in order to reduce the thickness of the electricity storage element 110. The amount of metallic lithium M can be set to such an amount that the negative electrode active material layer 133 can be doped by pre-doping with lithium ions described below.

  The length of the first uncoated region 130a and the second uncoated region 130b in the X direction is not particularly limited, but the length of the second uncoated region 130b in the X direction is preferably that of the winding core C. The length is about 1 / 2π times the diameter.

  As shown in FIG. 4A, the negative electrode terminal 131 is connected to the negative electrode current collector 132 in the peeled region 130 c and is drawn out of the negative electrode 130. In addition, the peeling region 130c 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 130c is not exposed. The type of the tape T is not particularly limited, and a tape having heat resistance and solvent resistance to the solvent of the electrolytic solution is preferably used. The negative electrode terminal 131 is, for example, a copper terminal.

  As shown in FIG. 3, the positive electrode 140 has 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 may 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 having through holes.

  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 may be a material in which the positive electrode active material is mixed with a binder resin, and may further include a conductive auxiliary material. 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, and includes, for example, styrene-butadiene rubber, polyethylene, polypropylene, polyethylene terephthalate, aromatic polyamide, carboxymethyl cellulose, fluorocarbon rubber, polyvinylidene fluoride, isoprene rubber, butadiene rubber and ethylene. Propylene rubber or the like may be used.

  The conduction aid is particles made of a conductive material and improves the conductivity between the positive electrode active materials. Examples of the conductive aid include carbon materials such as graphite and carbon black. These may be used alone or as a mixture of plural kinds. The conductive additive may be a metal material, a conductive polymer, or the like as long as it has conductivity.

  FIG. 5 is a schematic view showing the positive electrode 140 before winding, FIG. 5 (a) is a side view, and FIG. 5 (b) is a plan view. As shown in FIG. 5A, in the positive electrode 140 according to the present embodiment, the positive electrode active material layer 143 is formed on both surfaces of the third main surface 142a and the fourth main surface 142b of the positive electrode current collector 142, and A peeling region 140a in which 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 peeled region 140 a and is drawn out of the positive electrode 140. In addition, in the positive electrode 140, the peeling area 140a in which the positive electrode terminal 141 is disposed may be formed on the fourth main surface 142b. The peeling area 140a may be sealed with a tape or the like. The positive electrode terminal 141 is, for example, an aluminum terminal.

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

  The first separator 151 and the second separator 152 separate the negative electrode 130 and the positive electrode 140 and allow ions contained in an electrolytic solution described later to pass therethrough. Specifically, the first separator 151 and the second separator 152 may be woven cloth, non-woven cloth, synthetic resin microporous film, or the like. Further, the first separator 151 and the second separator 152 may be one 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 electricity storage device 110 according to the present embodiment has a negative electrode 130 and a positive electrode 140 laminated and wound via a first separator 151 and a second separator 152. 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. The fourth main surface 142b of 142 is configured to be on the winding outer side.

  Here, the storage element 110 has a configuration in which the outermost wound (outermost) electrode is the negative electrode 130, and as shown in FIG. 6, the second outer surface 132b of the outermost wound negative electrode current collector 132 is formed. The first uncoated region 130a is provided, and the second uncoated region 130b is provided at the end of the negative electrode current collector 132 which is the innermost wound side.

  Further, as shown in FIG. 6, the first main surface 132a of the negative electrode current collector 132 faces the positive electrode 140 (positive electrode active material layer 143) via the first separator 151. As shown in the figure, the second main surface 132b is a first region 132c facing the positive electrode 140 (the positive electrode active material layer 143) via the second separator 152 and the outermost winding outer side, and the second separator 152 is interposed therebetween. And a second region 132d that does not face the positive electrode 140 (positive electrode active material layer 143).

  As shown in FIG. 6, the second main surface 132b includes the second uncoated area 130b, and the second area 132d includes the first uncoated area 130a. The first uncoated region 130a according to the present embodiment is provided on the entire second region 132d as shown in FIG. 6, and the metallic lithium M is arranged therein. The first uncoated area 130a does not necessarily have to be provided in the entire second area 132d, and may be provided in a part of the second area 132d.

  The container 120 houses the power storage element 110. The upper surface and the lower surface of the container 120 may be closed by a lid (not shown). The material of the container 120 is not particularly limited, and may be, for example, a metal containing aluminum, titanium, nickel, iron as a main component, stainless steel, or the like.

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

[Effects of electrochemical devices]
Next, effects of the electrochemical device 100 will be described. In the electrochemical device 100 according to the present embodiment, when the electricity storage element 110 to which the metallic lithium M is bonded comes into contact with the electrolytic solution, the metallic lithium M is oxidized and dissolved, and the metallic lithium M is converted into lithium ions (Li +) and electrons (e−). ) Occurs. As a result, lithium ions diffuse into the electrolytic solution, are doped in the negative electrode active material contained in the negative electrode active material layer 133, and electrons flow into 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 lithium-ion capacitor so far, as a method of pre-doping lithium ions in the negative electrode, a method in which a lithium current collector to which metallic lithium is pasted is immersed in an electrolyte solution with a storage element connected to the negative electrode. Is widely practiced. However, in such a method, it is necessary to separately prepare a lithium current collector, and a step of connecting the lithium current collector to the negative electrode current collector is also required, which causes a problem of low productivity.

  Further, in the lithium ion capacitor as described above, when pre-doping the lithium ions in the negative electrode, problems such as voltage drop may occur due to 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, which is the supply source of lithium ions, does not face the positive electrode 140 via the separator 150, and is the outermost wound outermost. It is joined to the second main surface 132b.

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

  Further, in the electrochemical device 100 according to the present embodiment, as shown in FIG. 6, the metallic lithium M can be attached to the entire second region 132d on the outermost winding outer side of the second main surface 132b, so that the negative electrode A sufficient amount of lithium ions can be pre-doped in 130, and the capacity of the capacitor can be increased. In particular, since the second region 132d on the outermost winding side is a region that does not face the positive electrode 140 via the separator, by using this region as the first uncoated region 130a, the capacity of the storage element 110 is reduced. It is possible to dispose the metallic lithium M without doing so.

  Furthermore, since the negative electrode 130 is pre-doped with lithium ions, it is not necessary to separately prepare a lithium current collector unlike the conventional lithium ion capacitors, and the lithium current collector is connected to the negative electrode current collector 132. Since the process is not necessary, productivity can be secured.

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

  FIG. 7A shows a metal foil 232 in which a through hole serving as a source of the negative electrode current collector 132 is formed. The metal foil 232 is, for example, a copper foil. The thickness of the metal foil 232 is not particularly limited, but may be, for example, several tens μm to several hundreds μm.

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

  Subsequently, as shown in FIG. 7C, masking tape MT is attached to the surface 232a of the metal foil 232 at equal intervals along the X direction. Then, the above-mentioned negative electrode paste is applied again to the surface 232a of the metal foil 232 to which the masking tape MT is attached, and dried or cured to form a negative electrode on the surface 232a of the metal foil 232 as shown in FIG. The 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 off the masking tape MT, and the metal foil 232 is exposed as shown in FIG. 8B. The electrode layer 230 in which the peeling area 230a is formed is obtained. As a result, 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 predetermined intervals. The negative electrode active material layer 233 may be formed using a method other than masking.

  Then, as shown in FIG. 8C, between the negative electrode active material layers 233 formed on the surface 232a of the metal foil 232 with a predetermined space (along the dotted line R1 shown in FIG. 8C). The metal foil 232 and the negative electrode active material layer 233 on the back surface 232b are cut together. As a result, as shown in FIG. 9A, the first uncoated region 130a and the second uncoated region 130b are formed on the surface 232a of the metal foil 232.

  Next, the negative electrode active material layer 233 formed on the surface 232a of the metal foil 232 is partially peeled off to form a peeled 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 shown in FIG. 10A, a metal foil 242 having a through hole which is a source of the positive electrode current collector 142 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 μm to several hundreds 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. Thus, as shown in FIG. 10B, the 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 off, and as shown in FIG. A peeling area 240a where the metal foil 242 is exposed is formed. Then, as shown in the figure, the positive electrode terminal 241 is connected to the metal foil 242 in the peeled region 240a to obtain the positive electrode 140.

  Then, the negative electrode 130, the positive electrode 140, the 1st separator 251, and the 2nd separator 252 are laminated | stacked, and the laminated body 310 is obtained as shown in FIG.11 (a) and FIG.11 (b). At this time, as shown in FIG. 11A, the negative electrode 130 is wound inside, the positive electrode 140 is wound outside, and the second uncoated region 130b of the negative electrode 130 is wound on the winding core C side. The body 310 is placed. Note that FIG. 11B is a plan view of the laminated body 310 of FIG. 11A.

  Next, as shown in FIG. 11C, the positive electrode 140 is shifted in the X direction by a predetermined amount so that the positive electrode 140 does not face the second uncoated region 130b via the second separator 252. Then, as shown in the figure, the metal foil 232 and the negative electrode active material layer 233 in the second uncoated region 130b are sandwiched between the winding cores C, and the laminated body 310 is wound most in the first uncoated region 130a. The winding core C is wound clockwise so as to be on the outside of the gyration and wound.

  Thus, the wound body in which the back surface 232b of the metal foil 232 and the front surface 242a of the metal foil 242 are wound inside, and the front 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). ) Get.

  Subsequently, the lithium metal M is bonded to the first uncoated region 130a arranged on the outermost winding outer side of the wound body obtained by the above process (see FIG. 6) to obtain the electricity storage device 110. Next, the electricity storage device 110 to which the metallic lithium M is bonded is housed in the container 120 containing the electrolytic solution and sealed. As a result, lithium ions are doped into the negative electrode active material layer 233 from the metallic lithium M.

  The electrochemical device 100 can be manufactured as described above. The negative electrode terminal 231 corresponds to the negative electrode terminal 131, and the positive electrode terminal 241 corresponds to the positive electrode terminal 141. The peeling area 230b corresponds to the peeling area 130c, 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 is the negative electrode active material layer 133, and the positive electrode active material layer 243 is 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 view showing the manufacturing process of the electrochemical device 100 according to the modification, and FIG. 13 is a cross-sectional view of the electricity storage device 110 according to the modification.

  In the above embodiment, when the electrode layer 230 is cut, the metal foil 232 and the back surface 232b are entirely formed between the negative electrode active material layers 233 formed on the front surface 232a of the metal foil 232 with a predetermined gap. The negative electrode active material layer 233 is cut together (see FIG. 8C), but the present invention is not limited to this, and as shown in FIG. 12, the negative electrode active material layer 233 formed on the front surface 232 a of the metal foil 232 and the back surface are cut. The negative electrode active material layer 233 formed on the entire 232b and the metal foil 232 may be cut together (may be cut along the dotted line R2 shown in FIG. 12).

  By cutting the electrode layer 230 in this way, the negative electrode 130 may have the first negative electrode active material layer 133a formed in the first region 132c of the second main surface 132b and the second region 132d, 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 separated from the first negative electrode active material layer 133a. The negative electrode 130 has a first uncoated region 130a on the second main surface 132b between the first negative electrode active material layer 133a and the second negative electrode active material layer 133b, as shown in FIG. Becomes

  Thus, as shown in FIG. 13, the second negative electrode active material layer 133b is provided at the end of the negative electrode current collector 132. The cutting edge of the negative electrode current collector 132 may be sharp, but according to this configuration, since the second negative electrode active material layer 133b is on the cutting edge of the negative electrode current collector 132, the second edge by the cutting edge is formed. It is possible to prevent damage to the separator 152.

  Electrochemical devices according to Examples and Comparative Examples of the present invention were manufactured and characteristic tests were conducted.

[Fabrication of electrochemical device]
(Example)
The electrochemical device was produced as follows. First, non-graphitizable carbon, a conductive additive, 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 is provided at 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).

  Then, 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, the negative electrode paste was applied to the surface of the copper foil to which the masking tape was attached, and dried in an atmosphere of 80 ° C. After drying, the masking tape was peeled off to form an electrode layer having a peeled 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 peeled region was dried for 12 hours under a reduced pressure environment of 180 ° C. and 1 kPa or less.

  Subsequently, the electrode layer was cut, and the negative electrode active material layer formed on the surface of the copper foil was partially peeled off to form a peeled portion. Then, a copper terminal was crimped on the peeled portion, and the peeled portion was sealed together with the copper terminal with a tape to fabricate a negative electrode having a width of 27 mm and a length of 210 mm (see FIG. 9B).

  Next, activated carbon, a conductive additive, a binder and a thickener were mixed and kneaded in water to prepare a positive electrode paste. Then, an aluminum foil having a thickness of 30 μm, which is provided with gas permeability by forming through holes by etching, is used as a positive electrode current collector, and a positive electrode paste is applied on both front and back surfaces thereof, and a reduced pressure environment of 180 ° C. and 1 kPa or less is applied. An electrode layer having a positive electrode active material layer having a thickness of about 100 μm on both front and back surfaces was prepared by drying the layer for 12 hours (see FIG. 10B).

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

  Next, a separator made of cellulose having a density of 45% and a thickness of 35 μm was cut into a uniform width with a length of 30 mm to prepare a separator. The drying conditions for producing the separator were 160 ° C. and a reduced pressure environment of 1 kPa or less for 12 hours.

  Next, the positive electrode, the negative electrode, and the separator obtained above were laminated to obtain a laminated body, and then the laminated body was wound so that the back surface of the copper foil was the winding inner side and the surface was the winding outer side ( (See FIG. 11C). As a result, a wound body was formed in which one uncoated region formed on the surface of the copper foil was arranged inside the winding and the other uncoated region was arranged most outside the winding (FIG. 6). reference).

  Subsequently, metallic lithium having a thickness of 0.1 mm, a width of 25 mm, and a length of 25 mm was bonded to the uncoated region arranged on the outermost winding side of the wound body obtained above. Next, the separators were fixed to each other with tape, and rubber for sealing was fitted to the aluminum terminal and the copper terminal to obtain a power storage element.

Next, the above-mentioned electricity storage device was inserted into a case made of aluminum having an opening diameter of 12.5 mm in which an electrolytic solution was stored, and the case was sealed to manufacture an electrochemical device of this example. As the electrolytic solution, a propylene carbonate solution (1 mol / L) containing LiPF ₆ as a solute was adopted.

(Comparative example)
Subsequently, electrochemical devices according to Comparative Examples 1 to 3 were produced. The electrochemical device according to Comparative Example 1 was produced in the same manner as the electrochemical device according to the example, 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 carried out except that the outermost wound outer side of the negative electrode was made to protrude beyond the end of the positive electrode, and lithium metal was attached to the negative electrode active material layer at the part protruding from the end of the positive electrode. It was prepared in the same manner as the electrochemical device according to the example. Here, the amount of lithium metal was set to an amount such that the capacity of the electrochemical device according to Comparative Example 2 becomes equivalent to the capacity of the electrochemical device of Example 1.

  The electrochemical device according to Comparative Example 3 was prepared in the same manner as the electrochemical device according to Comparative Example 2 except that the negative electrode active material layer that was not involved in charging / discharging was removed.

[Characteristic evaluation]
Next, 20 electrochemical devices according to Examples and Comparative Examples were prepared, and the characteristics of each device stored in a 60 ° C. environment for 1 week were examined. Specifically, the capacity of each device, the presence or absence of voltage drop, and the remaining metallic lithium were examined. FIG. 14 is a table showing the results. The “acquisition capacity” shown in FIG. 14 is the average value of the acquisition capacities obtained from each device.

  The measurement conditions for the capacity measurement are as follows: charging voltage = 3.8V, charging current = 0.5A, CV (constant voltage) time = 10 minutes (0.5A is flown until the voltage reaches 3.8V, and 3.8V is reached). After reaching 3.8V, the voltage is maintained for 10 minutes), the discharge current was set to 0.05A, and each device was charged and discharged under the condition of 2.2V cutoff. In addition, the presence or absence of voltage drop was checked by conducting a 1000-time charge / discharge cycle test under the same conditions as above to see if any of the 20 had a voltage drop.

  As shown in FIG. 14, in the electrochemical devices according to the examples, no metallic lithium remained in any of the 20 devices, and the entire amount was pre-doped. In addition, it was confirmed that there was no device in which the voltage dropped, and the device had a high capacity.

  On the other hand, in the electrochemical device according to Comparative Example 1, as shown in FIG. 14, many devices in which lithium metal remained were confirmed, and the capacity was confirmed to be lower than that of the electrochemical devices of Examples. Was done.

  Further, in the electrochemical device according to Comparative Example 2, as shown in FIG. 14, no remaining lithium metal and no decrease in voltage were confirmed, and the capacity was the same as that of the electrochemical device of Example. Lithium metal was used more than chemical devices. As a result, the electrochemical device according to Comparative Example 2 requires a large amount of lithium metal in order to store the same capacity as the electrochemical device of the example, which may increase the manufacturing cost.

  Further, in the electrochemical device according to Comparative Example 3, as shown in FIG. 14, it was confirmed that the voltage dropped after the charge / discharge cycle test. It is speculated that this is due to the small amount of lithium powder generated during the process of pre-doping lithium metal into the negative electrode. From the above, it can be said that the electrochemical device according to the above-mentioned embodiment has a structure in which pre-doping of metallic lithium is favorably progressed and characteristic deterioration such as voltage drop is less likely to occur.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications are made.

100 ... Electrochemical device 110 ... Electric storage element 120 ... Container 130 ... Negative electrode 130a ... First uncoated region 130b ... Second uncoated region 131 ... Negative electrode terminal 132 ... -Negative electrode current collector 132a-First main surface 132b-Second main surface 132c-First region 132d-Second 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 ... Metallic lithium

Claims (9)

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, 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 that is a metal foil and has a third main surface and a fourth main surface opposite to the third main surface, and is formed on the third main surface and the fourth main surface. A positive electrode having a positive electrode active material layer
A separator for insulating the positive electrode and the negative electrode,
An electrolytic solution for immersing the positive electrode, the negative electrode, and the separator,
The positive electrode, the negative electrode, and the separator are laminated, 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. An electrochemical device wound in such a manner that the separator separates the positive electrode and the negative electrode from each other,
The first main surface faces the positive electrode via the separator,
The second main surface has a first region facing the positive electrode through the separator, and a second region that is the outermost wound side and does not face the positive electrode.
The second region includes a first uncoated region in which the negative electrode active material layer is formed on the first main surface, and the negative electrode active material layer is not formed on the second main surface, Metal lithium is bonded to the second main surface of the first uncoated region so as to face the negative electrode active material layer formed on the first main surface via the negative electrode current collector, An electrochemical device in which the negative electrode active material layer is pre-doped with lithium ions by being immersed in the electrolytic solution. The electrochemical device according to claim 1, wherein
An electrochemical device in which the first uncoated region is provided over the entire second region. The electrochemical device according to claim 1, wherein
The negative electrode has a first negative electrode active material layer formed in the first region and a second region formed in the second region, and is spaced apart from the first negative electrode active material layer to form an end of the negative electrode current collector. A second negative electrode active material layer formed in
The first uncoated region is an electrochemical device provided between the first negative electrode active material layer and the second negative electrode active material layer. An electrochemical device according to any one of claims 1 to 3,
The said 2nd main surface is an electrochemical device containing the 2nd uncoated area | region in which the said negative electrode active material layer is not provided in the edge part of the said negative electrode electrical power collector of the winding innermost side. The electrochemical device according to any one of claims 1 to 4,
The negative electrode current collector is an electrochemical device made of copper. An electrochemical device according to any one of claims 1 to 5,
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. A layer is formed, and the negative electrode active material layer is provided on the first main surface, and an uncoated region where the negative electrode active material layer is not provided is formed on the second main surface to form a negative electrode. Process,
Joining metallic lithium to the second major surface of the uncoated region;
A positive electrode current collector that is a metal foil and has a third main surface and a fourth main surface opposite to the third main surface, and is formed on the third main surface and the fourth main surface. A positive electrode having a positive electrode active material layer is prepared, a step of forming the laminate by laminating the positive electrode, the separator and the negative electrode,
The laminate is wound such 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 wound. Is a step of forming a storage element that separates the positive electrode and the negative electrode, the first main surface is opposed to the positive electrode through the separator, the second main surface is through the separator A power storage element having a first region facing the positive electrode and a second region that is the outermost winding and does not face the positive electrode, and the uncoated region is provided in the second region. A step of forming
A step of immersing the electricity storage element in an electrolytic solution to dope the negative electrode active material layer with lithium ions from the metallic lithium. A method of manufacturing an electrochemical device according to claim 7, wherein
In the step of producing the negative electrode, a negative electrode current collector, which is a metal foil having a first main surface and a second main surface opposite to the first main surface, is prepared.
A first negative electrode active material layer is formed on the entire first main surface, and a plurality of second negative electrode active material layers are formed on the second main surface at predetermined intervals.
A method of manufacturing an electrochemical device, wherein both the negative electrode current collector and the first negative electrode active material layer are cut between the second negative electrode active material layers. A method of manufacturing an electrochemical device according to claim 7, wherein
In the step of producing the negative electrode, a negative electrode current collector, which is a metal foil having a first main surface and a second main surface opposite to the first main surface, is prepared.
A first negative electrode active material layer is formed on the entire first main surface, and a plurality of second negative electrode active material layers are formed on the second main surface at predetermined intervals.
A method of manufacturing an electrochemical device, comprising cutting the second negative electrode active material layer, the negative electrode current collector, and the first negative electrode active material layer together.

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