JP2006031957A - Method of manufacturing battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a battery which can improve a yield easily by widening the width of manufacturing conditions. <P>SOLUTION: After a winding electrode is formed, the wiring electrode is sandwiched between sheathing members each made of a laminated film. Leads are pulled out to the outside of the sheathing member, and laminated by pressurizing while the peripheral edge of the sheathing member is being heated. In that case, the pressure is changed so that the pressure sequentially becomes high in order at multiple stages and is applied. Thus, the shock applied to the lead becomes small by this, and the disconnection of the lead is prevented. Moreover, since high pressure is applied at the final stage even if the temperature is not made higher than required, the sheathing members can be laminated certainly. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a battery manufacturing method using a laminate film as an exterior member.

  In recent years, portable electronic devices have been developed one after another, and batteries have become an important position as the power source. Since portable electronic devices are required to be small and light, the batteries are also required to be small and light. In addition, in order to efficiently use the storage space of the electronic device, a device having a large degree of freedom in shape is required. As a battery that satisfies such a requirement, for example, there is a battery using a laminate film as an exterior member (see, for example, Patent Document 1).

In this battery, the positive electrode and the negative electrode are housed inside the laminate film together with the electrolyte, and the peripheral portion of the laminate film is heated and pressed while being sealed (see, for example, Patent Document 2).
JP 2002-75297 A JP-A-9-199175

  However, in response to demands for further miniaturization and weight reduction of batteries, thinner laminate films and leads have been used, so the range of temperature and pressure when applying the laminate film is extremely high. However, there is a problem that the control must be performed with high accuracy. For example, if the pressure is a little high, the lead will be cut, whereas if the pressure is a little low, the sticking will be insufficient and the sealing performance will deteriorate. Further, when the temperature is raised slightly, the resin layer of the laminate film is easily melted, so that the leads are hard to cut and the sealing performance is improved. However, the metal layer of the laminate film comes into contact with the leads and a short circuit is likely to occur.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a battery manufacturing method that can broaden the manufacturing conditions and easily improve the yield.

  The battery manufacturing method according to the present invention is a method of manufacturing a battery in which an electrolyte is sealed together with a positive electrode and a negative electrode in an exterior member bonded with a peripheral edge of a laminate film, and each battery is attached to each of the positive electrode and the negative electrode. When the lead is pulled out from the inside to the outside of the exterior member and the peripheral portion of the exterior member is heated and bonded together, the pressure is applied by changing the pressure in multiple stages at least in the region where the lead is pulled out.

  According to the method for manufacturing a battery of the present invention, since the pressure is applied in multiple stages, the exterior member can be securely bonded while reducing the impact applied to the leads. Therefore, the range of temperature and pressure at the time of bonding can be widened, and the manufacturing yield can be easily improved.

  FIG. 1 shows the steps of a battery manufacturing method according to an embodiment of the present invention. 2 is an exploded view of the battery manufactured using the battery manufacturing method shown in FIG. 1, and FIG. 3 is an enlarged view of a part of the cross-sectional structure of the wound electrode body 10 shown in FIG. It represents. In this embodiment, a case where a battery using lithium (Li) as an electrode reactant is manufactured will be described.

  First, for example, a positive electrode active material, a conductive agent such as a carbon material, and a binder such as polyvinylidene fluoride are mixed to prepare a positive electrode mixture, and this positive electrode mixture is mixed with N-methyl-2-pyrrolidone or the like. To make a paste-like positive electrode mixture slurry. As the positive electrode active material, for example, one or more of positive electrode materials capable of inserting and extracting lithium are used.

As the positive electrode material capable of inserting and extracting lithium, for example, lithium-containing compounds such as lithium oxide, lithium phosphorus oxide, lithium sulfide, or an intercalation compound containing lithium are preferable. In particular, in order to increase the energy density, a lithium composite oxide or lithium phosphorus oxide represented by the general formula Li _x MIO ₂ or Li _y MIIPO ₄ is preferable. In the formula, MI and MII represent one or more transition metals such as cobalt (Co), nickel (Ni), manganese (Mn), iron (Fe), aluminum (Al), vanadium (V) and At least one of titanium (Ti) is preferred. The values of x and y vary depending on the charge / discharge state of the battery, and are usually values in the range of 0.05 ≦ x ≦ 1.10 and 0.05 ≦ y ≦ 1.10. Specific examples of the lithium composite oxide represented by Li _x MIO ₂ include lithium cobalt composite oxide (LiCoO ₂ ), lithium nickel composite oxide (LiNiO ₂ ), and lithium nickel cobalt composite oxide (Li _z Ni _v Co). _1-v O ₂ ; z and v are, for example, 0.05 <z <1, 0 <v <1), or lithium manganese composite oxide (LiMn ₂ O ₄ ) having a spinel crystal structure . A specific example of the lithium phosphorus oxide represented by Li _y MIIPO ₄ is LiFePO ₄ .

  Next, this positive electrode mixture slurry is applied to a positive electrode current collector 11A made of a metal foil such as an aluminum foil, a nickel foil, or a stainless foil, and the solvent is dried, followed by compression molding to form the positive electrode active material layer 11B. Then, the positive electrode 11 is produced (step S101).

  Subsequently, for example, a negative electrode active material and a binder such as polyvinylidene fluoride are mixed to prepare a negative electrode mixture, and the negative electrode mixture is dispersed in a solvent such as N-methyl-2-pyrrolidone and pasted. A negative electrode mixture slurry. As the negative electrode active material, for example, one or more negative electrode materials capable of inserting and extracting lithium are used.

  Examples of the negative electrode material capable of inserting and extracting lithium include carbon materials such as graphite, non-graphitizable carbon, and graphitizable carbon. Further, a single element, alloy or compound of a metal element capable of forming an alloy with lithium, or a single element, alloy or compound of a metalloid element capable of forming an alloy with lithium is also included.

Examples of such metal elements or metalloid elements include tin (Sn), lead (Pb), aluminum, indium (In), silicon (Si), zinc (Zn), antimony (Sb), bismuth (Bi), and cadmium. (Cd), magnesium (Mg), boron (B), gallium (Ga), germanium (Ge), arsenic (As), silver (Ag), zirconium (Zr), yttrium (Y) or hafnium (Hf). Tin or silicon is preferred. These alloys or compounds, for example, those represented by the chemical formula Ma _s Mb _t Li _u or a chemical formula Ma _p Mc _q Md _r,. In these chemical formulas, Ma represents at least one of a metal element and a metalloid element capable of forming an alloy with lithium, Mb represents at least one of a metal element and a metalloid element other than lithium and Ma, Mc represents at least one of nonmetallic elements, and Md represents at least one of metallic elements and metalloid elements other than Ma. The values of s, t, u, p, q, and r are s> 0, t ≧ 0, u ≧ 0, p> 0, q> 0, and r ≧ 0, respectively.

  Next, this negative electrode mixture slurry is applied to, for example, a negative electrode current collector 12A made of a metal foil such as a copper foil, a nickel foil or a stainless steel foil, and the solvent is dried. The layer 12B is formed, and the negative electrode 12 is produced (step S102).

  Subsequently, the lead 13 is attached to the positive electrode current collector 11A and the lead 14 is attached to the negative electrode current collector 12A, and then the electrolyte layer 15 is formed on the positive electrode active material layer 11B and the negative electrode active material layer 12B (step) S103). The electrolyte layer 15 is prepared by, for example, mixing an electrolytic solution, a polymer compound, and a solvent for the polymer compound, and applying the mixture onto the positive electrode active material layer 11B and the negative electrode active material layer 12B and drying the mixture. It is formed by volatilizing the solvent.

  As the electrolytic solution, a solution in which an electrolyte salt such as a lithium salt is dissolved in a solvent is used. Examples of the solvent include propylene carbonate, ethylene carbonate, butylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, 1,3-dioxol-2-one, 4-vinyl-1,3-dioxolan-2-one, and ethylene. Sulfide, γ-butyrolactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, diethyl ether, sulfolane, methyl Non-aqueous solvents such as sulfolane, acetonitrile, propionitrile, acetic acid ester, butyric acid ester, or propionic acid ester are listed. As the solvent, one kind may be used alone, or two or more kinds may be mixed and used.

Examples of the lithium salt include LiPF ₆ , LiAsF ₆ , LiBF ₄ , LiClO ₄ , LiB (C ₆ H ₅ ) ₄ , LiCH ₃ SO ₃ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C _{2 F 5 SO 2) 2,} LiN (C 4 F 9 SO 2) (CF 3 SO 2), LiC (CF 3 SO 2) 3, LiC 4 F 9 SO 3, LiAlCl 4, LiSiF 6, LiCl or LiBr are Can be mentioned. One lithium salt may be used alone, or two or more lithium salts may be mixed and used.

  Examples of the polymer compound include polyacrylonitrile, polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, polytetrafluoroethylene, polyhexafluoropropylene, polyethylene oxide, polypropylene oxide, polyphosphazene, polysiloxane, Examples thereof include polyvinyl acetate, polyvinyl alcohol, polymethyl methacrylate, polyacrylic acid, polymethacrylic acid, styrene-butadiene rubber, nitrile-butadiene rubber, polystyrene, and polycarbonate.

  After that, the positive electrode 11 and the negative electrode 12 on which the electrolyte layer 15 is formed are stacked via the separator 16 and wound in the longitudinal direction to form the wound electrode body 10 (step S104). For the separator 16, for example, a porous film made of a polyolefin-based material such as polypropylene or polyethylene, or a porous film made of an inorganic material such as a ceramic nonwoven fabric is used, and these two or more kinds of porous films are laminated. Or may be used.

  Next, the wound electrode body 10 is sandwiched between the exterior members 20 made of a laminate film, and the leads 13 and 14 are pulled out from the inside to the outside of the exterior member 20 (step S105). For example, a laminate film in which a metal layer is sandwiched between resin layers is used. Specifically, for example, a nylon film, an aluminum foil, and a polyolefin film laminated in this order are preferable.

  Subsequently, the peripheral edge portion of the exterior member 20 is heated and pressed and bonded together (step S106). For example, although not shown, the wound electrode body 10 sandwiched between the exterior members 20 is placed between two upper and lower pressing members each having a depression formed in accordance with the shape of the wound electrode body 10, and the pressing member is heated. The exterior member 20 is pressurized by moving up and down.

  At that time, the pressure is applied in various stages. For example, as shown in FIG. 4, pressurization is performed in two stages so that the pressure in the second stage is higher than that in the first stage. That is, the pressure is changed so as to increase in order. By applying pressure in such a multi-stage manner, the impact applied to the leads 13 and 14 is reduced compared to the case of applying pressure in one stage, and the cutting of the leads 13 and 14 is suppressed. In addition, since a high pressure is applied in the final stage, high sealing performance can be obtained without increasing the temperature more than necessary.

  The pressure in each stage does not need to be constant in that stage, and may change gradually as shown in FIG. 4, for example. This is due to the pressurization speed. If the pressurization speed is slow, the pressure gradually increases to the set pressure. If the pressurization speed is high, the pressure reaches the set pressure immediately and the pressure is maintained for a certain time. The time for each stage is arbitrary.

  Note that each side of the peripheral portion of the exterior member 20 may be bonded at the same time, but the side from which the leads 13 and 14 are drawn out may be bonded separately from the other side. For example, when one laminate film is used by bending, the side from which the leads 13 and 14 are pulled out and the other two sides may be bonded separately, and when two laminate films are used, The side from which the leads 13 and 14 are pulled out may be bonded to the other three sides separately. In this case, at least the sides from which the leads 13 and 14 are drawn are bonded together by changing the pressure in multiple stages as described above. Other sides need not be changed in multiple stages.

  Thereby, the battery shown in FIGS. 2 and 3 is completed.

  Moreover, you may manufacture as shown in FIG. First, for example, after producing the positive electrode and the negative electrode 12 in the same manner as the above manufacturing method (steps S201 and S202), the lead 13 is attached to the positive electrode current collector 11A, and the lead 14 is attached to the negative electrode current collector 12A. And the negative electrode 12 are stacked via the separator 16 and wound (step S203). Next, this is sandwiched between the exterior members 20 made of a laminate film, and the peripheral edge of the exterior member 20 is heated and pressed while leaving one side to form a bag (step S204). At that time, the leads 13 and 14 are pulled out from the open side of the exterior member 20.

  Subsequently, an electrolyte composition containing an electrolytic solution and a monomer that is a raw material for the polymer compound is injected into the exterior member 20 (step S205), and the open side of the exterior member 20, that is, the side from which the leads 13 and 14 are drawn out. These are bonded together by applying pressure while heating (step S206). At that time, the pressure is applied in various stages as described in the above production method. Thereafter, the electrolyte composition is polymerized, for example, by heating. Thereby, the battery shown in FIGS. 2 and 3 is completed.

  In the above process, the side where the leads 13 and 14 are pulled out in step S204 is defined as an open side, and the open side is bonded in step S206 by changing the pressure in multiple stages. , 14 may be bonded together, and the other side may be an open side. In that case, the pressure is changed in multiple steps in step S204 where the sides from which the leads 13 and 14 are drawn are bonded.

  As described above, according to the present embodiment, when the region from which the lead is drawn out of the peripheral portion of the exterior member 20 is bonded, the pressure is changed in multiple stages, so that the impact on the lead is reduced. However, the exterior member 20 can be securely bonded. Therefore, the range of manufacturing conditions such as temperature and pressure at the time of bonding can be widened, and the manufacturing yield can be easily improved.

  Further, specific embodiments of the present invention will be described in detail.

  A battery having the structure shown in FIGS. 2 and 3 was fabricated according to the steps shown in FIG. As the exterior member 20, a member having a thickness of 85 μm in which a nylon film, an aluminum foil, and a polypropylene film are bonded together in this order was used. When bonding the peripheral edge of the exterior member 20, each side was bonded simultaneously using a pressing member in which a groove was formed in accordance with the leads 13 and 14. A plurality of pressing members were prepared by changing the depth of the groove corresponding to the leads 13 and 14 within the range of 95 μm to 170 μm, and the battery was fabricated by changing the pressure and temperature conditions for each. The pressure was changed in two stages and the first stage set pressure was 0.1 MPa, and the second stage set pressure was 0.15 MPa or 0.2 MPa. The set pressure is the ultimate pressure at each stage. The temperature was 185 ° C., 195 ° C., or 205 ° C.

  Further, as a comparative example, a battery was fabricated in the same manner except that the pressure at the time of pasting the peripheral portion of the exterior member was applied in one step. The set pressure, that is, the ultimate pressure, was 0.1 MPa, 0.15 MPa, or 0.2 MPa. In the pressing member, the depth of the groove corresponding to the leads 13 and 14 was changed within the range of 95 μm to 140 μm.

Each manufactured battery was inspected for whether or not the leads 13 and 14 were cut, and whether or not there was a gap between the leads 13 and 14 and the exterior member 20. The results are shown in FIGS. In FIG. 6, 7, ○ is no cutting of the leads 13 and 14, and shows a good no gaps in the bonding of the outer member 20, × ^* indicates defective cutting of the leads 13 and 14 were observed , X ^** indicates a defective product in which a gap was recognized in the bonding of the exterior member.

  As can be seen from a comparison between FIG. 6 and FIG. 7, according to the embodiment in which the pressure was changed in two steps, a good product was obtained within a wide range even if the groove depth, pressure and temperature were changed. On the other hand, according to the comparative example in which the pressure was applied in one step, a good product could be obtained only within a part of a narrow range. That is, it has been found that if the pressure is applied in multiple stages when the peripheral edge portion of the exterior member 20 is bonded, the manufacturing conditions can be widened and the manufacturing yield can be easily improved.

  Although the present invention has been described with reference to the embodiments and examples, the present invention is not limited to the above embodiments and examples, and various modifications can be made. For example, in the above-described embodiments and examples, the configuration of the battery has been specifically described. However, the present invention manufactures a battery having a different configuration as long as the battery uses a laminate film for the exterior member 20. The same applies to the case.

  For example, the separator 16 may be impregnated with an electrolytic solution, that is, a liquid electrolyte, without forming the electrolyte layer 15. The electrolyte layer 15 may be formed of another material, for example, a polymer compound having ion conductivity dispersed without using a solvent, or an inorganic ion conductor. Furthermore, you may make it comprise the positive electrode 11 and the negative electrode 12 with another material, and an electrode reactant is not limited to lithium. In addition, the positive electrode 11 and the negative electrode 12 may not be wound to form the wound electrode body 10, but may be a laminate in which one or more positive electrodes and negative electrodes are laminated, or the positive electrode and the negative electrode are laminated. It may be a folded structure.

It is a flowchart showing the manufacturing method of the battery which concerns on one embodiment of this invention. It is a perspective view which decomposes | disassembles and represents the structure of the battery produced using the manufacturing method of the battery shown in FIG. FIG. 3 is an enlarged sectional view showing a part of a wound electrode body in the battery shown in FIG. 2. It is a figure for demonstrating process step S106 shown in FIG. It is a flowchart showing the manufacturing method of the other battery which concerns on one embodiment of this invention. It is a relationship figure showing the manufacturing conditions in the Example of this invention, and the result of good and bad. It is a relationship figure showing the manufacturing conditions in a comparative example, and the result of good and bad.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Winding electrode body, 11 ... Positive electrode, 11A ... Positive electrode collector, 11B ... Positive electrode active material layer, 12 ... Negative electrode, 12A ... Negative electrode collector, 12B ... Negative electrode active material layer, 13, 14 ... Lead, 15 ... electrolyte layer, 16 ... separator, 20 ... exterior member.

Claims (3)

A battery manufacturing method in which an electrolyte is encapsulated together with a positive electrode and a negative electrode inside an exterior member bonded with a peripheral edge of a laminate film,
When each lead attached to the positive electrode and the negative electrode is pulled out from the inside of the exterior member to the outside, and the peripheral edge of the exterior member is heated and pressed and bonded together, the pressure is multistage in at least the region where the lead is pulled out A method for producing a battery, wherein the battery is added after being changed.   2. The battery manufacturing method according to claim 1, wherein the pressure is changed so as to increase in order. 2. The battery manufacturing method according to claim 1, wherein the pressurization is performed in two stages, and the pressure in the second stage is made higher than that in the first stage.

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