JP2005243455A - Electrochemical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrochemical device which hardly causes a short circuit. <P>SOLUTION: This device is provided with a pair of electrode plates 20, 30, a separator to separate the pair of electrode plate 20, 30, and an electrolyte (not illustrated) contacted with the separator and the pair of electrode plates 20, 30. Then, respective electrode plates 20, 30 are folded alternately in different directions for respective prescribed lengths, and form meandering shapes each having a plurality of plates 20a, 30a arranged in parallel. Furthermore, as for the pair of electrode parts 20, 30, the extension direction of the plate 30a of one electrode plate 30 and the extension direction of the plate 20a of the other electrode plate 20 intersect to each other, and the plate 30a of one electrode plate and the plate 20a of the other electrode plate 20 are alternately laminated and form a laminate 10. Then, a separator 42 has a cylindrical shape in which the other electrode plate 30 is wrapped along the longitudinal direction of one electrode plate 30. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrochemical device such as a secondary battery or an electrochemical capacitor.

Lithium ion secondary batteries that achieve high energy density are widely used as power sources for portable devices such as mobile phones, notebook computers, and PDAs. For example, Japanese Patent Laid-Open No. 2003-229178 proposes a coin-type battery in which a positive electrode and a negative electrode are provided with a plate-shaped separator folded in a zigzag shape.
JP 2003-229178 A

  However, in the lithium ion secondary battery having the separator folded in a zigzag manner as described above, the separator is turned up during production or the like, and the positive electrode and the negative electrode are often short-circuited.

  This invention is made | formed in view of the said subject, and it aims at providing the electrochemical element which is hard to raise | generate a short circuit.

  The electrochemical device according to the present invention includes a pair of electrode plates, a separator that separates the pair of electrode plates from each other, and an electrolyte that contacts the separator and the pair of electrode plates. Each electrode plate is alternately bent in a different direction for each predetermined length to form a spelled shape having a plurality of plate portions arranged in parallel. The pair of electrode plates are arranged so that the extending direction of the plate portion of one electrode plate and the extending direction of the plate portion of the other electrode plate intersect each other. Furthermore, the plate part of one electrode plate and the plate part of the other electrode plate are alternately laminated, and the pair of electrode plates form a laminate. And the separator is made into the cylinder shape extended along the length direction of one electrode plate, and enveloping this one electrode plate from the outer side.

  According to the electrochemical device of the present invention, since one electrode plate is accommodated in the cylindrical separator, the separator is less likely to be turned over as compared with the conventional one, and the electrode plates in the laminate are not separated from each other. Generation | occurrence | production of a short circuit can fully be suppressed.

  Moreover, since one electrode plate is accommodated in the cylindrical separator and the separator and the electrode plate can be handled integrally, it is possible to relatively easily form a laminate.

  Here, this separator has a pair of separator sheets that sandwich one electrode plate from above and below in the thickness direction, and both edges of one separator sheet and both edges of the other separator sheet are heat-sealed to each other. It is preferable.

  Such an embodiment is easy to implement, and a thin electrochemical device can be easily realized.

  The separator preferably has a bag shape in which one end of the cylinder is closed and one electrode plate is accommodated therein.

  According to this, a short circuit between the end face (end part) of one electrode plate and the other part can be effectively suppressed.

  In addition, the electrochemical device described above is: Each of the pair of electrode plates has a current collector layer and active material layers respectively formed on the front and back of the current collector layer. 2. an exterior body that accommodates the laminate is further provided; This exterior body has a pair of conductive members that sandwich the stacked body in the stacking direction. 4. The plate portion of one electrode plate is disposed at one end in the stacking direction of the laminate, while the plate portion of the other electrode plate is disposed at the other end in the stacking direction of the stack. The current collector layer of one electrode plate disposed at one end in the stacking direction of the laminate is in direct contact with one conductive member, and the current collector layer of the other electrode plate disposed at the other end of the stack in the stacking direction Is preferably in direct contact with the other conductive member.

  According to this, in an electrochemical device such as a coin type, the resistance between the conductive member of the outer package functioning as a terminal and the current collector of the laminated body, that is, the internal resistance can be reduced, and high-speed charging is easy. Yes.

In addition, 1. Each of the pair of electrode plates has a current collector layer and active material layers respectively formed on the front and back of the current collector layer. 2. the electrolyte contains a lithium salt; The loading amount of the positive electrode active material in one active material layer is 4.0 to 7.0 mg / cm ² . The loading amount of the negative electrode active material in the other active material layer is preferably 2.0 to 4.0 mg / cm ² .

  According to this, since the amount of the negative electrode active material is sufficiently thinner than in the past, lithium ion intercalation at the negative electrode is suitably performed at a sufficiently high speed, and there is little deterioration in capacity even when high-speed charging is performed. Become.

ADVANTAGE OF THE INVENTION According to this invention, the electrochemical element which is hard to raise | generate a short circuit is provided.

(First embodiment)
First, a lithium ion secondary battery as an electrochemical device according to this embodiment will be described in detail. 1 is a cross-sectional view of a coin-type lithium ion secondary battery 1 according to the present embodiment, FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1, and FIG. 4 (a) is a perspective view of the cathode structure 40 in the stack of FIG. 3, and FIG. 4 (b) is a perspective view of the anode 20 in the stack of FIG.

  As shown in FIGS. 1 and 2, the coin-type lithium ion secondary battery 1 mainly includes a laminate 10, an electrolyte solution (not shown) impregnated in the laminate 10, and the laminate 10 in a sealed state. And an exterior body 60 to be housed.

(Laminate)
As shown in FIGS. 1 to 3, the laminate 10 includes an anode (electrode plate) 20 folded in a zigzag shape and a cathode structure 40 folded in a zigzag shape in a direction intersecting the anode 20. These are stacked alternately.

(anode)
First, the anode 20 will be described. As shown in FIGS. 1 and 2, the anode 20 has negative electrode active material layers 22 and 22 formed on both surfaces of a plate-like anode current collector 21.

  The anode current collector 21 is not particularly limited as long as it is formed from a metal material that is usually used as an anode current collector of a lithium ion secondary battery, and examples thereof include copper and nickel.

  On the other hand, the negative electrode active material layer 22 is a layer containing a negative electrode active material, a conductive additive, a binder and the like.

The negative electrode active material is a carbon material having a graphite structure, and occlusion and release of lithium ions, desorption and insertion of lithium ions, or lithium ions and counterions of the lithium ions (for example, ClO ₄ ⁻ ). Doping and dedoping can proceed reversibly.

  Examples of such a carbon material include natural graphite, artificial graphite, and amorphous carbon.

Here, the loading amount of the carbon material in the negative electrode active material layer 22 of the anode 20 is not particularly limited, but may be 2.0 to 4.0 mg / cm ^{2 in} order to reduce capacity deterioration after the rapid charge / discharge cycle. preferable. Here, the supported amount is the weight of the carbon material fixed per unit surface area of the anode current collector 21.

  The conductive aid is not particularly limited as long as the conductivity of the anode 20 is improved, and a known conductive aid can be used. Examples thereof include carbon blacks, carbon materials, fine metal powders such as copper, nickel, stainless steel, and iron, and a mixture of carbon materials and fine metal powders.

  The binder is not particularly limited as long as the negative electrode active material particles and the conductive auxiliary particles can be bound to the anode current collector 21, and a known binder can be used. For example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PEA), ethylene-tetrafluoro Examples thereof include fluoropolymers such as ethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), and polyvinyl fluoride (PVF), and styrene-butadiene rubber.

  Next, the shape of the anode 20 will be described. As shown in FIGS. 3 and 5, the anode 20 is provided with a plurality of disk parts (plate parts) 20 a and a connection part 20 b that is provided on an end surface of each disk part 20 a and connects the disk parts 20 a in series. And have. In the anode 20, the connecting portions 20b are alternately bent in different directions in a U shape to form a zigzag shape, and the disc portions 20a are arranged in parallel to each other.

(Cathode structure)
Next, the cathode structure 40 will be described. As shown in FIGS. 1, 2, and 4, the cathode structure 40 includes a plate-like cathode (electrode plate) 30 and a separator bag that is formed in a bag shape and accommodates the cathode 30 inside and covers the periphery of the cathode 30. A body (separator) 42.

  As shown in FIGS. 1 and 2, the cathode 30 includes a conductive cathode current collector 31 and positive electrode active material layers 32 and 32 formed on both surfaces of the cathode current collector 31.

  The material of the cathode current collector 31 is not particularly limited as long as it is a metal material that is usually used as a cathode current collector of a lithium ion secondary battery, and examples thereof include aluminum.

  On the other hand, the positive electrode active material layer 32 is a layer containing a positive electrode active material, a conductive additive, a binder, and the like.

The positive electrode active material is a lithium ion occlusion and release, lithium ion desorption and insertion (intercalation), or doping and dedoping of lithium ions and counterions (eg, ClO ₄ ⁻ ) of the lithium ions. The electrode is not particularly limited as long as it can be reversibly advanced, and a known electrode active material can be used. For example, lithium cobalt oxide (LiCoO _2), lithium nickel oxide (LiNiO _2), lithium manganese spinel (LiMn ₂ O _4), and the general formula: represented by _{LiNi x Co y Mn z O 2} (x + y + z = 1) Composite metal oxide, lithium vanadium compound (LiV ₂ O ₅ ), olivine type LiMPO ₄ (where M represents Co, Ni, Mn or Fe), composite such as lithium titanate (Li ₄ Ti ₅ O ₁₂ ) A metal oxide is mentioned.

The amount of the positive electrode active material supported per unit surface area of the cathode current collector 31 in the positive electrode active material layer 32 can be arbitrarily set according to the amount of the negative electrode active material supported by the anode 20, but 4.0 to 7 It is preferably 0.0 mg / cm ² .

  As each component other than the positive electrode active material contained in the positive electrode active material layer 32, the same material as that constituting the negative electrode active material layer 22 of the anode 20 can be used. Also, the positive electrode active material layer 32 preferably contains the same electron conductive particles as the anode 20.

  As shown in FIG. 4, the cathode 30 has a plurality of disk parts (plate parts) 30a and a connection part 30b that is provided on the end surface of each disk part 30a and connects the disk parts 30a in series. And have. The cathode 30 has a zigzag shape in which the connecting portions 30b are alternately bent in a U shape in different directions. Here, the disc parts 30a are arranged in parallel to each other.

(Separator bag)
As shown in FIGS. 1, 2, and 4, the separator bag body 42 is a bag body that accommodates the cathode 30 and is folded along the one main surface so as to cover one main surface of the cathode 30. And the separator sheet 41b arranged in a zigzag manner along the other main surface so as to cover the other main surface of the cathode 30.

  As shown in FIG. 4A, the width of the separator sheets 41a and 41b is larger than the width of the cathode 30, that is, the diameter of the disc portion 30a of the cathode 30. 2, 3, and 4 (a), the separator sheet 41 a extends from the disc portion 30 aa at one end of the cathode 30 (upper side in FIGS. 2 and 4 (a)) to the spelling of the cathode 30. The length extends to the disc portion 30ab at the other end of the cathode 30 (the lower end in FIGS. 2 and 4A) along the folded shape and covers the cathode 30 in its entirety. On the other hand, the length of the separator sheet 41b is shorter than the length of the separator sheet 41a, and the disc portion 30ab at the other end of the cathode 30 is exposed to the outside. Therefore, the separator sheet 41b is not interposed between the disk portion 30ab and the can body 61 of the exterior body 60 described later.

  The cathode 30 is sandwiched between the separator sheets 41a and 41b, and a portion where the separator sheet 41a and the separator sheet 41b face each other, for example, both edge portions 43g of the separator sheets 41a and 41b (FIGS. 2 and 4). And the end portions 43d outside the disk portion 30aa (see FIGS. 1 and 4) are integrated by heat fusion with each other, and the separator sheets 41a and 41b are separators that accommodate the cathode 30 therein. A bag body 42 is formed.

  The material of the separator sheets 41a and 41b is not particularly limited as long as the separator sheets 41a and 41b are formed of an electrically insulating porous body, and a separator material used for a known secondary battery element can be used. For example, as the electrically insulating porous body, at least one structure selected from the group consisting of a laminate of films made of polyethylene, polypropylene or polyolefin, a stretched film of a mixture of the above resins, or cellulose, polyester and polypropylene Examples thereof include a fiber nonwoven fabric made of a material.

  1 to 3, in the stacked body 10, the direction in which the disk portion 20 a of the anode 20 extends (the horizontal direction in FIG. 1) and the disk portion of the cathode 30 in the cathode structure 40. The direction in which 30a extends (the horizontal direction in FIG. 2) intersects at a substantially right angle, and is accommodated in the disc portion 20a of the anode 20 and the separator bag body 42 as shown in FIGS. The disk portions 30a of the cathodes 30 are alternately stacked.

  Therefore, in the laminated body 10, the negative electrode active material layer 22 of the anode 20 and the positive electrode active material layer 32 of the cathode 30 face each other through the separator sheets 41a and 41b, and these three constitute secondary battery elements, respectively. To do.

  Here, as shown in FIG. 3, the connecting portion 20 b of the anode 20 is disposed so as to straddle the edge of the cathode structure 40.

  4 and 5, the number of the disk portions 20a in the anode 20 and the number of the disk portions 30a in the cathode 30 are the same. As shown in FIGS. The disk portion 20aa of the anode 20 is disposed at the upper end in the stacking direction 10 (upper side in FIG. 1), and the disk portion 30ab of the cathode 30 is disposed at the lower end in the stacking direction 10 (lower side in FIG. 2). Is arranged.

  Here, as shown in FIG. 1, the negative electrode active material layer 22 is not formed in the portion of the disk portion 20aa at the upper end in the stacking direction that comes into contact with the can body 63 of the exterior body, which will be described later. The inner surface of 63 and the anode current collector 21 of the anode 20 are in direct contact.

  In addition, as shown in FIG. 2, in the disc portion 30ab at the lower end in the stacking direction, the positive electrode active material layer 32 is not formed on the portion of the exterior body 60 that contacts the can body 61. 30 cathode current collectors 31 are in direct contact.

(Electrolyte solution)
The electrolyte solution (not shown) is contained in the negative electrode active material layer 22 of the anode 20, the positive electrode active material layer 32 of the cathode 30, and the pores of the separator bag body 42. The electrolyte solution is not particularly limited, and an electrolyte solution containing a lithium salt (electrolyte aqueous solution, electrolyte solution using an organic solvent) used for a known lithium ion secondary battery element can be used. However, the electrolyte aqueous solution is preferably an electrolyte solution (non-aqueous electrolyte solution) using an organic solvent because the electrochemical decomposition voltage is low, and the withstand voltage during charging is limited to a low level. As the aqueous electrolyte solution for the secondary battery element, a lithium salt dissolved in a non-aqueous solvent (organic solvent) is preferably used. Examples of the lithium salt include LiPF ₆ , LiClO ₄ , LiBF ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiCF ₃ , CF ₂ SO ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiN (CF ₃ SO ₂ ) ₂ , Salts such as LiN (CF ₃ CF ₂ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ), LiN (CF ₃ CF ₂ CO) ₂ are used. In addition, these salts may be used individually by 1 type, and may use 2 or more types together.

  Moreover, as an organic solvent, the solvent currently used for the known secondary battery element can be used. For example, propylene carbonate, ethylene carbonate, diethyl carbonate and the like are preferable. These may be used alone or in combination of two or more at any ratio.

  In the present embodiment, the electrolyte solution may be a gel electrolyte obtained by adding a gelling agent in addition to liquid. Further, instead of the electrolyte solution, a solid electrolyte (a solid polymer electrolyte or an electrolyte made of an ion conductive inorganic material) may be contained.

(Exterior body)
The exterior body 60 includes a pair of metal can bodies (conductive members) 61 and 63 and a gasket 65 that electrically insulates the can bodies 61 and 63.

  Each of the can body 61 and the can body 63 is a cylindrical body having a bottom surface, and the inner diameter of the cylindrical portion of one can body 61 is larger than the outer diameter of the cylindrical portion of the other can body 63. . In these can bodies 61 and 63, the cylindrical portion of the can body 63 is inserted into the can body 61, and the bottom surface of the can body 63 and the bottom surface of the can body 61 form the stack 10 in the stacking direction (vertical direction). Is sandwiched between. Then, the cylindrical portion of the can body 61 is replaced with the cylindrical shape of the can body 63 in a state where the gasket 65 is interposed between the outer peripheral surface of the cylindrical portion of the can body 61 and the inner peripheral surface of the cylindrical portion of the can body 63. The laminated body 10 is sealed by crimping with respect to a part.

  The can body 63 directly contacts the current collector 21 of the anode 20 and functions as a negative electrode terminal, while the can body 61 directly contacts the cathode current collector 31 of the cathode 30 and functions as a positive electrode terminal.

(Production method)
Next, an example of a method for manufacturing the above-described lithium ion secondary battery 1 will be described.

  First, the coating liquid (slurry) containing the constituent material for forming the negative electrode active material layer 22 of the anode 20 and the positive electrode active material layer 32 of the cathode 30 is adjusted. The negative electrode coating liquid can include the above-described negative electrode active material, conductive additive, binder, and the like, and the positive electrode coating liquid can include the above-described positive electrode active material, conductive additive, binder, and the like. The solvent used in the coating solution is not particularly limited as long as the binder can be dissolved and the active material and the conductive auxiliary agent can be dispersed. For example, N-methyl-2-pyrrolidone, N, N-dimethylformamide and the like can be used.

  Next, an anode current collector 21 made of copper, nickel or the like, and a cathode current collector 31 made of aluminum or the like are prepared. And the coating liquid for negative electrodes is apply | coated to both surfaces of the anode electrical power collector 21, and it is made to dry, the negative electrode active material layer 22 is formed on both surfaces, and the sheet | seat for anodes is obtained. Also, a cathode coating liquid is applied to both sides of the cathode current collector 31 and dried to form a cathode active material layer 32 on both sides to obtain a cathode sheet.

  Here, the method for applying each coating solution to each current collector is not particularly limited, and may be appropriately determined according to the material and shape of the current collector metal plate. Examples thereof include a metal mask printing method, an electrostatic coating method, a dip coating method, a spray coating method, a roll coating method, a doctor blade method, a gravure coating method, and a screen printing method.

Here, the anode coating liquid is applied so that the amount of the negative electrode active material supported by the negative electrode active material layer 22 satisfies 2.0 to 4.0 mg / cm ² . Moreover, it is preferable to apply | coat a cathode coating liquid so that the positive electrode active material carrying amount of the positive electrode active material layer 32 may satisfy | fill 4.0-7.0 mg / cm < ² >. After the application, the negative electrode active material layer 22 and the positive electrode active material layer 32 are subjected to a rolling process using a lithographic press, a calender roll, or the like as necessary.

  Then, as shown in FIG. 6A, the anode sheet is cut into a shape in which a plurality of disk portions 20a are connected in a row via connection portions 20b, and a plate-like anode 20 is obtained.

  Further, as shown in FIG. 6B, the cathode sheet is cut into a shape in which a plurality of disk portions 30a are connected in a row via the connection portions 30b, whereby the flat cathode 30 is obtained.

  Here, the lateral width of the connecting portions 20b and 30b is smaller than the lateral width (diameter) of the disc portions 20a and 30a. Further, the diameters of the disk portions 20a and 30a can be made approximately the same. Furthermore, it is preferable that the length 30bL of the connecting portion 30b of the cathode 30 is shorter than the length 20bL of the connecting portion 20b of the anode 20 in order to suitably perform the folding described later.

  Also, one surface of the disk portion 20ab at one end of the anode 20 and one surface of the disk portion 30ab at one end of the cathode 30 are not coated with a coating solution in advance, or the active material layers 22 and 32 are formed. The current collectors 21 and 31 are exposed on the surface.

  Subsequently, as shown in FIGS. 6C and 6D, strip-shaped separator sheets 41a and 41b are prepared. The separator sheets 41a and 41b are formed by cutting an insulating porous material into a predetermined shape and size. Here, for example, the separator sheet 41a has a size that can cover all of the flat plate-like cathode 30, while the separator sheet 41b has a circular portion of the other flat plate-like cathode 30 leaving one disc portion 30a. It is set as the magnitude | size which can cover the board part 30a. Here, the edge part of each separator sheet 41a, 41b is made into the circular shape corresponding to each disk part 20a, 30a, and is rounded.

  And as shown in FIG.6 (e), the cathode 30 is mounted on the separator sheet 41a, and the separator sheet 41b is mounted on it. Here, the cathode 30 and the separator sheet 41b are arranged so that the disc portion 30aa where the cathode current collector 31 is exposed in the cathode 30 is exposed on the surface. The separator sheets 41a and 41b are heated while applying pressure in the thickness direction to these three layers from above and below, so that the edge portions 43g and the end portions 43d of the separator sheet 41a and the separator sheet 41b are heat-sealed. Then, a bag-like separator bag body 42 for accommodating the cathode 30 is formed. Thereby, the cathode structure 40 is completed.

  Subsequently, as illustrated in FIG. 7A, the disk part 30 a at the end of the cathode structure 40 opposite to the disk part 30 aa is overlaid on the disk part 20 aa of the anode 20. At this time, the anode 20 and the cathode structure 40, that is, the cathode 30 intersect with each other at about 90 degrees.

  Then, as shown in FIG. 7B, the connecting portion 20b of the anode 20 is bent into a U shape, and the second disc portion 20a of the anode 20 is placed on the disc portion 30a at the end of the cathode structure 40. Overlapping. Subsequently, although not shown, the cathode structure 40 is bent at the connection portion 30b of the cathode 30, and the second disk portion of the cathode structure 40 is placed on the second disk portion 20a of the anode 20. Stack 30a. Hereinafter, the connection parts 20b and 30b are alternately bent, and the disk parts 20a and the disk parts 30a are alternately stacked to complete the laminate 10 shown in FIG. Here, the anode 20 and the cathode structure 40 are exposed so that the anode current collector exposed surface of the disc portion 20aa and the cathode current collector exposed surface of the disc portion 30a are exposed on the outermost surface of the laminated body 10 to be completed. The front and back of the overlay are determined in advance.

  Then, such a laminate 10 is impregnated with the above-described electrolyte solution and sealed in the outer package 60, whereby the coin-type lithium ion secondary battery 1 shown in FIGS. 1 and 2 is completed.

  According to such a lithium ion secondary battery 1, the cathode 30 is accommodated in the separator bag body 42. Therefore, for example, when the laminate is manufactured when the anode 20 and the cathode 30 are folded together, the separator is hardly turned over when the electrolyte solution is impregnated into the laminate, or when the laminate is sealed in the outer package. . Therefore, the generation of defective products due to a short circuit between the anode 20 and the cathode 30 is sufficiently reduced, and the yield is improved.

  In particular, in the present embodiment, the separator bag body 42 covers both the side surface 30 s (see FIG. 1) along the length direction of the cathode 30 and the end surface 30 e perpendicular to the length direction of the cathode 30. The suppression effect is remarkable. Note that the effect of the present invention is exhibited even when a cylindrical separator having an open end 30e portion of the cathode 30 is used.

  Moreover, when the cathode 30 is accommodated in the separator bag body 42 and integrated as the cathode structure 40, the operation itself of forming the laminate by bending the anode 20 and the cathode structure 40 alternately is simplified.

  In the laminate 10, the anode current collector 21 of the anode 20 and the can body 63 are in direct contact with each other without the negative electrode active material layer 22 interposed therebetween, and the cathode current collector 31 of the cathode 30 and the can body. 61 is in direct contact with no positive electrode active material layer 32 interposed. Therefore, the laminate 10 and the cans 61 and 63 as external terminals can be electrically connected with a sufficiently low resistance, and the internal resistance of the lithium ion secondary battery 1 is sufficiently reduced. Therefore, charging with a large current, that is, rapid charging is possible.

Furthermore, the negative electrode active material carrying amount of the negative electrode active material layer 22 is set to 2.0 to 4.0 mg / cm ² , the positive electrode active material carrying amount of the positive electrode active material layer 32 is set to 4.0 to 7.0 mg / cm ² , Both are sufficiently smaller than the prior art, that is, the thickness is reduced. Therefore, polarization in the negative electrode active material layer 22 is less likely to occur than in the past, and even when a large current is supplied to the lithium ion secondary battery, lithium ions are intercalated in the negative electrode active material layer 22 at a sufficiently high speed, and the capacity is increased. Deterioration is less likely to occur. In addition, the thickness of the conventional negative electrode active material layer is about 0.1-0.5 mm, that is, the negative electrode active material carrying amount is about 8.0-15.0 mg / cm ² , and this effect is remarkable.

  In addition, this invention is not limited to the said embodiment, It can take various deformation | transformation aspects.

  For example, in the above embodiment, the cathode 30 is sealed in the separator bag body 42, but the anode 20 may be sealed in the separator bag body 42.

  In addition, the laminated body 10 is enclosed in metal cans 61 and 63 to form a coin-type battery, but the laminated body 10 is enclosed in an aluminum laminate pack and is electrically connected to the laminated body 10 as a conductive member. The operation can be performed even if the lead wires are provided so as to protrude from the inside of the pack.

  Moreover, in the said embodiment, although the anode 20 and the cathode 30 are equipped with the disk parts 20a and 30a 5 each, if it has the disk parts 20a and 30b and the same number, it will not restrict to this. .

  Moreover, in the said embodiment, you may change arbitrarily the shape of the disc part 20a instead of a disc, such as a rectangular plate and a square plate.

  For example, in the description of the above embodiment, the case where the electrochemical element is a lithium ion secondary battery has been described. However, the electrochemical element of the present invention is not limited to the lithium ion secondary battery, Secondary batteries other than lithium ion secondary batteries such as secondary batteries (using the electrode of the present invention for the positive electrode and metallic lithium for the negative electrode), electric double layer capacitors, pseudo-capacitance capacitors, pseudo capacitors, redox capacitors It may be an electrochemical capacitor or the like. In the case of an electrochemical element other than a lithium ion secondary battery, an electrode active material that is suitable for each electrochemical element may be used.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in more detail, this invention is not limited to these Examples at all.

(Example 1)
First, the anode 20 was produced by the following procedure. First, artificial graphite as a negative electrode active material, carbon black as a conductive additive, and polyvinylidene fluoride (PVdF) as a binder are prepared, and the weight ratio of these is negative electrode active material: conductive member: binder = 90: 8: After mixing and dispersing so as to be 2, an appropriate amount of N-methyl-pyrrolidone (NMP) was added as a solvent to adjust the viscosity, thereby preparing a slurry-like coating solution for negative electrode.

Next, a copper foil (thickness: 16 μm) is prepared as an anode current collector, and both sides of the copper foil are applied by a doctor blade method so that the negative electrode coating solution is 3.5 mg / cm ^2. And dried at 110 ° C. to obtain an anode sheet. Thereafter, the negative electrode active material layer of the anode sheet was pressed and rolled using a calendar roll. Further, the anode sheet was punched into a predetermined shape shown in FIG.

Next, the cathode 30 was produced by the following procedure. First, LiMn _0.33 Ni _0.33 Co _0.34 O ₂ (subscript is an atomic ratio) as a positive electrode active material, carbon black as a conductive aid, and PVdF as a binder are prepared. Positive electrode active material: Conductive aid: Binder = 90: 6: 4 After mixing, an appropriate amount of N-methyl-2-pyrrolidone as a solvent is mixed with this to adjust the viscosity, and the slurry positive electrode The coating solution was adjusted.

Subsequently, an aluminum foil (thickness: 20 μm) was prepared as a cathode current collector, and a positive electrode coating solution was applied to the aluminum foil by a doctor blade method so that the active material loading was 5.5 mg / cm ^2. It dried and rolled and it was set as the cathode sheet. Then, this cathode sheet was punched into the shape shown in FIG.

  Next, a porous film made of polyolefin (thickness 25 μm, Gurley aeration time 100 s) was punched into a predetermined shape shown in FIGS. 6C and 6D to obtain a pair of separator sheets 41a and 41b.

  Subsequently, the separator sheet 41a, the cathode 30, and the separator sheet 41b are laminated in this order, and are heat-sealed by sandwiching them from above and below to form the separator bag body 42. The cathode structure in which the cathode 30 is accommodated in the separator bag body 42 40 was obtained.

  Further, as shown in FIGS. 7A and 7B, the anode 20 and the cathode structure 40 are crossed and alternately folded, thereby forming the laminate 10 as shown in FIG. At both ends in the stacking direction of the stacked body 10, the anode current collector 21 of the anode 20 and the cathode current collector 31 of the cathode current collector 31 were exposed on the surface, respectively.

Next, the laminate 10 was impregnated with an electrolyte solution. As an electrolyte solution, a mixture of propylene carbonate (PC), ethylene carbonate (EC), and diethyl carbonate (DEC) at a predetermined volume ratio is used as a solvent, and 1.5 mol / L LiPF ₆ is used as a solute. Using.

  Then, the laminate 10 impregnated with the electrolyte was enclosed in a metal coin-type outer package 60 to complete the lithium ion secondary battery as shown in FIG. The size of the outer package 60 was 2032 type (diameter 20 mm, thickness 3.2 mm), and the capacity was 45 mAh. Here, ten such lithium ion secondary batteries were produced.

(Example 2)
A negative electrode active material layer 22 is formed on the surface of the anode 20 exposed to the outside in the stacking direction of the stacked body 10, and a positive electrode active material layer 32 is formed on the surface of the cathode 30 exposed to the outside in the stacking direction. Produced a lithium ion secondary battery in the same manner as the lithium ion secondary battery of Example 1. That is, in this lithium ion secondary battery, the anode current collector 21 and the can 63 are electrically connected via the negative electrode active material layer 22, and the cathode current collector 31 is connected via the positive electrode active material layer 32. The can 61 is electrically connected.

(Comparative Example 1)
A lithium ion secondary battery was prepared in the same manner as in Example 1 except that the bag-shaped separator bag body 42 was not used and the cathode 30 was simply sandwiched between the pair of separator sheets 41a and 41b (not thermally fused). did.

  The lithium ion secondary battery thus obtained is subjected to a constant current constant voltage charging at 4.2 V and a discharging at a constant current five times, and is necessary for charging in each charging cycle. Time was measured. The charging current in each cycle was 2C, 5C, 10C, 20C, and 30C in order, and the discharging current was 1C. Here, the charging was terminated when the current value was reduced to 0.05 C, and the discharging was terminated when the terminal voltage reached 2.5V. The results are shown in FIG.

  The lithium ion secondary batteries of Example 1 and Example 2 had almost no short-circuiting of electrodes, whereas the lithium ion secondary battery of Comparative Example 1 was short-circuited and could not be charged / discharged.

  Moreover, the lithium ion secondary battery of Example 1 and the lithium ion secondary battery of Example 2 were able to be charged at 2C or more.

  Furthermore, the charging time of the lithium ion secondary battery of Example 1 was shorter than that of the lithium ion secondary battery of Example 2. This difference is considered to be because the internal resistance of the battery was lowered and the polarization was reduced by the direct contact between the current collector and the can.

FIG. 1 is a cross-sectional view of a coin-type lithium ion secondary battery 1 according to this embodiment. 2 is a cross-sectional view taken along the line II-II in FIG. FIG. 3 is a perspective view of the laminate 10 in FIG. 4 is a perspective view of the cathode structure 40 in the laminate of FIG. FIG. 5 is a perspective view of the anode 20 in the laminate of FIG. FIG. 6A to FIG. 6E are diagrams illustrating a process of creating one lithium ion secondary battery. FIG. 7A to FIG. 7B are explanatory diagrams following FIG. 6A to FIG. 6E for explaining a method of producing a lithium ion secondary battery. 6 is a table showing the results of Examples 1 and 2 of Comparative Example 2;

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Lithium ion secondary battery, 10 ... Laminated body, 20 ... Anode (electrode plate), 20a ... Disc part (plate part), 21 ... Anode collector layer, 22 ... Negative electrode active material layer, 30 ... Cathode ( Electrode plate), 30a ... disc portion (plate portion), 31 ... cathode current collector layer, 32 ... positive electrode active material layer, 41a, 41b ... separator sheet, 42 ... separator bag body (separator), 60 ... exterior body, 61, 63 ... Can bodies (conductive members).

Claims (5)

A pair of electrode plates;
A separator for separating the pair of electrode plates from each other;
An electrolyte in contact with the separator and the pair of electrode plates,
Each of the electrode plates is alternately bent in different directions for each predetermined length to form a zigzag shape having a plurality of plate portions arranged in parallel,
The pair of electrode plates are arranged such that the extending direction of the plate portion of one electrode plate and the extending direction of the plate portion of the other electrode plate intersect each other,
The plate portion of one electrode plate and the plate portion of the other electrode plate are alternately laminated, and the pair of electrode plates form a laminate,
The said separator is the electrochemical device made into the cylinder shape extended along the length direction of one electrode plate, and enveloping said one electrode plate from the outer side.   The separator has a pair of separator sheets that sandwich the one electrode plate from above and below in the thickness direction, and both edges of one separator sheet and both edges of the other separator sheet are heat-sealed to each other. 1. Electrochemical device.   The electrochemical device according to claim 1, wherein the separator has a bag shape in which one end of the cylinder is closed and the one electrode plate is accommodated. Each of the pair of electrode plates has a current collector layer and an active material layer formed on each side of the current collector layer,
It further comprises an exterior body that houses the laminate,
The exterior body has a pair of conductive members that sandwich the stacked body in the stacking direction,
The plate portion of one electrode plate is disposed at one end in the stacking direction of the laminate, while the plate portion of the other electrode plate is disposed at the other end of the stack in the stacking direction.
The current collector layer of one electrode plate disposed at one end of the laminate in the stacking direction is in direct contact with one conductive member, and the current collector of the other electrode plate disposed at the other end of the stack in the stacking direction. The electrochemical device according to any one of claims 1 to 3, wherein the body layer is in direct contact with the other conductive member. Each of the pair of electrode plates has a current collector layer and an active material layer formed on each side of the current collector layer,
The electrolyte includes a lithium salt;
The loading amount of the positive electrode active material in one active material layer is 4.0 to 7.0 mg / cm ² ,
The electrochemical device according to any one of claims 1 to 3 supported amount of the negative electrode active material in the other of the active material layer is 2.0~4.0mg / cm ^2.

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