JP2017091929A - Separator for battery, battery including the separator, method for manufacturing the separator, and method for manufacturing the battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a positional deviation between an electrode and a separator by forming a bag-shaped separator with a sufficient bond strength when a heat resistant resin is used for the separator, thereby preventing a short-circuit between electrodes while improving the productivity of batteries.SOLUTION: A separator 13 includes a porous sheet having a first portion and a second portion arranged to face each other and containing a resin with a melting point or a glass transition temperature of 200°C or above. The porous sheet has a portion present over the first portion and the second portion, and is cylindrically formed by a junction that integrates the first portion and the second portion.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a battery separator processed into a cylindrical shape so as to accommodate an electrode, and a battery having the separator. The present invention also relates to a method for manufacturing the separator and a method for manufacturing a battery.

  With the rapid market expansion of notebook PCs, mobile phones, electric cars, etc., energy storage devices such as capacitors and secondary batteries are actively researched. Among them, the secondary battery is attractive in that it can store more energy. At present, there is a demand for a secondary battery having a higher energy density, and it has been proposed to use a metal such as tin or silicon or an alloy or oxide thereof as a negative electrode active material as a candidate. It has also been proposed to use a battery having a large theoretical capacity such as a lithium-air battery. However, the higher the energy density of the battery, the greater the energy that can be released, so safety considerations are more important.

  For example, in an electricity storage device such as a lithium ion secondary battery, the separator plays a role in preventing a short circuit between the positive electrode and the negative electrode and effectively moving lithium ions. So far, polyolefin-based microporous separators made of polypropylene or polyethylene materials have been mainly used. This is because the shutdown effect of these materials contributes to the safety of the battery when it generates heat. However, in the polyolefin-based microporous separator, the melting point of polypropylene or polyethylene material is generally 110 ° C. to 160 ° C. Therefore, when used in a battery having a high energy density, thermal contraction of the separator occurs at a high temperature, and the separator melts before a shutdown effect is obtained, and a short circuit between the electrodes may occur over a wide area.

  In place of such an organic polymer separator, it has also been proposed to use an inorganic material or an organic polymer-inorganic composite material in a lithium ion battery. Although the inorganic material does not have the above-described shutdown effect, the inorganic material has an overwhelmingly higher melting point than the organic polymer, and therefore may be excellent in safety. In addition, it has also been proposed to prevent the separator from melting and getting a job using an organic polymer having a high heat resistance.

  Patent Document 1 (Japanese Patent No. 5644506) discloses a separator using an aramid porous film containing an aramid (aromatic polyamide) resin which is a high heat resistance resin. Patent Document 2 (Japanese Patent No. 5585555) further discloses a separator using a polyimide resin which is a high heat resistance resin.

  Patent Document 3 (International Publication No. 2006/095579) discloses a stacked battery using a separator processed into a bag shape. The separator is formed by superposing two sheets made of a thermoplastic resin and thermally fusing the outer peripheral edge continuously or intermittently. The positive electrode or the negative electrode is accommodated in the separator, whereby the separator is displaced due to vibration during transportation or the like, thereby preventing a short circuit between the positive electrode and the negative electrode.

  Patent Document 4 (Japanese Patent Laid-Open No. 2015-69745) discloses a bag-shaped separator formed by combining at least two sides of a porous film made of an aramid resin. As a method for bonding the porous membrane, a method of drying after applying a solvent to the bonding portion, bonding, a method using an adhesive, a method of sandwiching a low melting point thermoplastic resin in the bonding portion, pressurizing and heat treatment, A method is described in which a porous film is subjected to surface treatment such as low-temperature plasma treatment and then laminated by compression and heating, and a method of stitching with a thread made of aramid is described. Patent Document 5 (Japanese Patent Application Laid-Open No. 5-290822) discloses a separator that includes an amorphous aramid resin and can be processed into a bag by melting.

  Patent Document 6 (Japanese Patent Application Laid-Open No. 2006-59717) discloses a sheet-like or bag-like separator made of a fiber assembly including fibers made of aramid and / or polyimide. As a method for forming a fiber assembly into a bag shape, a joining method by heat fusion is disclosed. Patent Document 7 (International Publication No. 2014/1999979) also discloses a separator formed into a bag shape by overlapping two sheet materials made of a high heat-resistant resin such as an aramid resin and a polyimide resin, and engaging the peripheral portions thereof. It is disclosed.

Patent No. 5644506 Japanese Patent No. 5585555 International Publication No. 2006/095579 JP2015-69745A JP-A-5-290822 JP 2006-59717 A International Publication No. 2014/1999979

  In the separators using high heat resistance resins such as aramid resin and polyimide resin described in Patent Documents 1 and 2, the problem of thermal shrinkage at high temperature is considered to be small. However, a separator using a high heat-resistant resin cannot be processed into a bag shape by heat fusion like the separator described in Patent Document 3. As a result, the separator may be displaced during battery assembly or battery transportation, and the positive electrode and the negative electrode may be short-circuited.

  On the other hand, Patent Document 4 describes several methods for joining porous films made of an aramid resin without using thermal welding. These methods are industrially used in the following points. There is a problem in production. In the method using a solvent and the method using an adhesive, it may be considered that the bonding may not be appropriately performed depending on the application method and the application amount of the solvent and the adhesive. In the method using a thermoplastic resin, the thermoplastic resin melts at a high temperature, and there is a possibility that the function of joining may not be performed. The method by stitching is difficult to realize. Furthermore, since the method using the low-temperature plasma treatment results in bonding between the surfaces of the porous membranes, the qualitative contact area on the actual bonded surface is small, and as a result, sufficient bonding strength may not be obtained.

  In the separator described in Patent Document 5, the heat resistance of the separator is lowered due to the inclusion of the amorphous aramid resin, resulting in the loss of the original superiority of the high heat resistant resin.

  Furthermore, in the method described in Patent Document 6, it is difficult to actually bond an aramid resin or a polyimide resin by thermal fusion. Since the method described in Patent Document 7 is joining by mechanical meshing between sheet materials, there is a possibility that sufficient joint strength cannot be obtained unless a sufficient meshing area is secured.

  Therefore, the present invention prevents the positional deviation between the electrode and the separator by enabling the formation of a bag-like separator with sufficient bonding strength when a heat resistant resin is used for the separator, thereby producing a battery. It aims at preventing the short circuit between electrodes, improving a property.

The separator of the present invention is a separator for a battery in which a positive electrode and a negative electrode are arranged to face each other,
One porous sheet that is folded in half, or two sheets that are superposed, containing a resin having a melting point or a glass transition temperature of 200 ° C. or more, having a first part and a second part that are arranged opposite to each other Having a porous sheet of
The porous sheet is formed by joining the first part and the second part, the part having a part that extends over the first part and the second part. It is formed in a cylindrical shape that can accommodate the positive electrode or the negative electrode.

The battery of the present invention comprises a positive electrode and a negative electrode arranged opposite to each other,
The separator of the present invention,
Have
The positive electrode or the negative electrode is accommodated in the separator.

The present invention also provides a separator manufacturing method and a battery manufacturing method. The method for producing a separator of the present invention is a method for producing a separator for a battery in which a positive electrode and a negative electrode are opposed to each other,
1 or 2 porous sheets containing a resin having a melting point or a glass transition temperature of 200 ° C. or higher, which are folded in half to constitute a first part and a second part that face each other Preparing two porous sheets constituting the first part and the second part facing each other by being laminated, or
Using a bonding agent containing a solvent capable of melting or swelling a resin having a melting point or glass transition temperature of 200 ° C. or higher, a cylindrical body that can accommodate the positive electrode or the negative electrode of the battery is formed. Forming a joining portion that integrates the first portion and the second portion with a portion that straddles the first portion and the second portion; and
Have

The battery manufacturing method of the present invention is a porous sheet containing a resin having a melting point or glass transition temperature of 200 ° C. or higher, and the first part and the second part facing each other by being folded in half. A step of preparing one porous sheet constituting, or two porous sheets constituting a first part and a second part facing each other by being superposed, a positive electrode and a negative electrode;
Disposing the positive electrode or the negative electrode between the first portion and the second portion;
The cylindrical body that can accommodate the positive electrode or the negative electrode is formed using a bonding agent containing a solvent capable of melting or swelling a resin having a melting point or a glass transition temperature of 200 ° C. or higher. Forming a joint that integrates the first portion and the second portion with a portion that extends across the first portion and the second portion; and
After the positive electrode or the negative electrode is disposed between the first portion and the second portion, and the cylindrical body is formed by the first portion and the second portion, Obtaining an electrode laminate by laminating a positive electrode and the negative electrode;
Encapsulating the electrode laminate together with an electrolyte in an exterior body;
Have

  According to the present invention, since the joining portion for forming the porous sheet containing the heat-resistant resin having a melting point or glass transition temperature of 200 ° C. or more into a cylindrical shape is formed with sufficient joining strength, It is possible to obtain a separator that hardly breaks the quality sheet. By accommodating the positive electrode or the negative electrode in such a separator, positional deviation between the electrode and the separator can be prevented, and a short circuit between the electrodes can be well prevented.

1 is an exploded perspective view of a secondary battery according to an embodiment of the present invention. It is a disassembled perspective view of the electrode laminated body shown in FIG. FIG. 3 is a perspective view of the negative electrode and the separator before the negative electrode shown in FIG. 2 is inserted into the separator. It is a disassembled perspective view of the secondary battery by one Embodiment of this invention with which the positive electrode terminal and the negative electrode terminal were pulled out in the same direction. It is a figure explaining an example of the manufacturing method of the separator by the present invention. It is a figure explaining the other example of the manufacturing method of the separator by this invention. It is a figure which shows typically one form of the cross section of the junction part of the separator in this invention. It is a figure which shows typically the other form of the cross section of the junction part of the separator in this invention. It is a schematic diagram which shows an example of the electric vehicle provided with the battery of this invention. It is a schematic diagram which shows an example of the electrical storage apparatus provided with the battery of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Electrode laminate and electricity storage device]
The electrode laminate and the electricity storage device can be applied to various devices as long as they can accumulate charges. A typical device includes a battery such as a lithium ion secondary battery, but can be applied to other secondary batteries and capacitors such as an electric double layer capacitor. In the following description, a lithium ion secondary battery will be described as an example. However, the present invention is not limited to this, and the shape, configuration, and material may be changed as appropriate according to the type of device to which the present invention is applied. it can.

  There are various types of secondary batteries such as a cylindrical type, a flat wound rectangular type, a laminated rectangular type, a coin type, a flat wound laminated type, and a laminated laminated type, depending on the structure and shape of the electrode. The present invention is applicable to any of these types. Among these, the shape of the secondary battery to which the present invention is applied is preferably a laminated laminate type from the viewpoint that the separator is not easily broken. Hereinafter, a laminated laminate type secondary battery will be described.

  Referring to FIG. 1, a book having an electrode laminate 10 and an exterior body that encloses the electrode laminate 10 together with an electrolytic solution by surrounding the electrode laminate 10 from both sides in the thickness direction with exterior materials 21 and 22. An exploded perspective view of a secondary battery 1 according to an embodiment of the invention is shown. A negative electrode terminal 31 and a positive electrode terminal 32 are connected to the electrode laminate 10 such that a part thereof protrudes from the exterior body.

  As shown in FIGS. 2 and 3, the electrode laminate 10 has a configuration in which a plurality of negative electrodes 11 and a plurality of positive electrodes 12 are arranged to face each other alternately. The separator 13 has a cylindrical body formed in a cylindrical shape using a porous sheet. In the example shown in the figure, the separator 13 as a whole is formed in a bag shape having one end opened and the other end closed, and the positive electrode 12 is inserted from one end side of the separator 13 opened. Thus, the negative electrode 11 and the positive electrode 12 are arranged to face each other via the separator 13, and the negative electrode 11 and the positive electrode 12 are kept in an insulated state by the separator 13.

  The negative electrode 11 includes a negative electrode current collector 11a that can be formed of a metal foil, and a negative electrode active material 11b formed on both surfaces or one surface of the negative electrode current collector 11a. The negative electrode current collector 11a is formed to have an extension portion that extends from a portion facing the separator 13, and the negative electrode active material 11b is not formed in the extension portion.

  Similarly to the negative electrode 11, the positive electrode 12 includes a positive electrode current collector 12 a that can be formed by metal stay and a positive electrode active material 12 b formed on both surfaces or one surface of the positive electrode current collector 12 a. The positive electrode current collector 12a is formed to have an extended portion extending from the portion accommodated in the separator 13, and the positive electrode active material 12b is not formed in the extended portion.

  The negative electrode 11 and the positive electrode 12 are laminated so that the respective extensions extend in opposite directions. The plurality of negative electrodes 11 are electrically connected to each other by welding to form a negative electrode tab 10a shown in FIG. The plurality of positive electrodes 12 are also electrically connected to each other by welding to form a positive electrode tab 10b shown in FIG. The negative electrode terminal 31 is electrically connected to the negative electrode tab 10a, and the positive electrode terminal 32 is electrically connected to the positive electrode tab 10b.

  Since the electrode laminate 10 having such a planar laminated structure does not have a portion with a small radius of curvature (a region close to the winding core of the wound structure), it is more charged / discharged than an electrode element having a wound structure. There is an advantage that it is not easily affected by the volume change of the electrode. That is, it is effective for an electrode laminate using an active material that easily causes volume expansion.

  In the example shown in FIGS. 1 to 3, the negative electrode terminal 31 and the positive electrode terminal 32 are drawn out in directions opposite to each other, but the drawing direction of the negative electrode terminal 31 and the positive electrode terminal 32 may be arbitrary. For example, as shown in FIG. 4, the negative electrode terminal 31 and the positive electrode terminal 32 may be drawn out from the same side of the electrode stack 10, and although not shown, the negative electrode terminal 31 from two adjacent sides of the electrode stack 10. And the positive electrode terminal 32 may be pulled out, respectively. In any case, the extension (tab) that is not covered with the active material of the negative electrode 11 and the positive electrode 12 is formed at a position corresponding to the position where the negative electrode terminal 31 and the positive electrode terminal 32 are drawn.

  In the example shown in the figure, the positive electrode 12 is accommodated in the separator 13. However, if the negative electrode 11 and the positive electrode 12 can be opposed to each other with the separator 13 therebetween, the negative electrode 11 is not the positive electrode 12 but the separator 13. It can also be stored. Furthermore, the negative electrode 11 and the positive electrode 12 may be accommodated in the separator 13, and the negative electrode 11 accommodated in the separator 13 and the positive electrode 12 accommodated in the separator 13 may be arranged to face each other.

  As described above, the separator 13 is formed in a cylindrical shape, and the negative electrode 11 or the positive electrode 12 is accommodated therein, so that the position shift of the separator 13 can be prevented.

  Hereafter, each element which comprises the secondary battery mentioned above is demonstrated in detail.

(Separator)
The separator 13 is configured as a cylindrical body in which a porous sheet containing a heat resistant resin as a base material is formed into a flat cylindrical shape. The cylindrical body has a size that can accommodate the positive electrode 12 or the negative electrode 11. By accommodating the positive electrode 12 or the negative electrode 11 in the cylindrical body, the positive electrode 12 and the negative electrode 11 are disposed to face each other via the cylindrical body portion existing between the positive electrode 12 and the negative electrode 11. 11 functions as a separator that prevents a short circuit with 11. If the porous sheet does not have electrical conductivity, can prevent a short circuit between the positive electrode 12 and the negative electrode 11, and can form a cylindrical body so as to have ionic conductivity, Any inorganic filler and / or organic filler may be included. Moreover, the inorganic porous layer may be laminated | stacked on the porous sheet.

The heat resistant resin contained in the porous sheet is preferably a resin having a melting point or glass transition temperature of 200 ° C. or higher, and more preferably a melting point or glass transition temperature of 250 ° C. or higher. Examples of such resins include polyamide resins, aramid resins (aromatic polyimide resins), polyphenylene sulfide resins, polysulfone resins, polyether sulfone resins, polyether imide resins, polyether ether ketone resins, and polyamide imide resins. It is done. Examples of inorganic fillers that can contain a heat-resistant resin or that can constitute the inorganic porous layer include inorganic oxides such as aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, BaTiO ₂ , ZrO, and alumina-silica composite oxide. Inorganic nitride particles such as aluminum nitride and boron nitride; Covalent crystal particles such as silicone and diamond; Slightly soluble ion crystal particles such as barium sulfate, calcium fluoride and barium fluoride; Clay such as talc and montmorillonite Examples thereof include fine particles. These inorganic fillers may be subjected to element substitution, surface treatment, or solid solution as necessary. Moreover, these inorganic fillers may be used individually by 1 type, and may be used in combination of 2 or more type. Among these inorganic fillers, inorganic oxide particles are particularly preferable from the viewpoints of stability in an electrolytic solution and potential stability.

  The cylindrical body is not limited to a form in which both ends are opened, but may have a bag-like form in which only one end is opened and the other end is closed. A cylindrical body in which only one end of the cylindrical body is open can be preferably used because it can hold the positive electrode 12 or the negative electrode 11 more stably and can more effectively prevent a short circuit between the positive electrode 12 and the negative electrode 11.

  As shown in FIG. 5, the cylindrical body includes a first portion 131 and a second portion 132 that are arranged to face each other by overlapping two porous sheets, for example, at appropriate portions along the outer edge. It can comprise by joining. Alternatively, as shown in FIG. 6, the first portion 131 and the second portion 132 that are arranged to face each other by folding a single porous sheet in two are joined together at an appropriate location along the outer edge, for example. By doing so, the cylindrical body can be configured. In any case, by joining the first portion 131 and the second portion 132, the cylindrical body is a joint portion that is a portion where the first portion 131 and the second portion 132 are joined. 133. In the joint portion 133, the first portion 131 and the second portion 132 are integrated.

  Here, the first portion 131 and the second portion 132 have one separator 13 regardless of whether one separator 13 is made of one porous sheet or two porous sheets. The part of the porous sheet which comprises is meant. Further, the first portion 131 and the second portion 132 that are arranged to face each other preferably have the same size and shape, but the size and shape are different from each other as long as the positive electrode 12 or the negative electrode 11 can be covered. It may be. In the illustrated form, the first portion 131 and the second portion 132 have the same size and shape.

  The formation of the bonding portion 133 may be performed after the positive electrode 12 or the negative electrode 11 is disposed between the first portion 131 and the second portion 132, or may be performed before being disposed. By forming the bonding portion 133 after the positive electrode 12 or the negative electrode 11 is disposed between the first portion 131 and the second portion 132, the positive electrode 12 or the negative electrode 11 is accommodated simultaneously with the formation of the bonding portion 133. Separator 13 is obtained. In addition, when the bonding portion 133 is formed before the positive electrode 12 or the negative electrode 11 is disposed between the first portion 131 and the second portion 132, the positive electrode 12 is connected to the cylindrical separator 13 formed by bonding. Alternatively, the negative electrode 11 is inserted, whereby the separator 13 in which the positive electrode 12 or the negative electrode 11 is accommodated is obtained.

  A bonding agent can be used for forming the bonding portion 133. As the bonding agent, for example, a solvent capable of melting or swelling a heat-resistant resin having a melting point or glass transition temperature of 200 ° C. or higher can be used. In many cases, the heat resistant resin can be melted by a polar solvent because of its strong intermolecular force. Examples of such a solvent include N-methylpyrrolidone (NMP), dimethylsulfoxide (DMSO), N, N-dimethylacetamide (DMAc), N, N-dimethylformamide (DMF), chloroform, dichloromethane acetone, tetrahydrofuran ( THF), tetramethylurea (TMUA) and the like.

  The solvent is applied to a portion that forms the joint portion 133 of the opposing surfaces of at least one of the first portion 131 and the second portion 132 of the porous sheet. After application of the solvent, the first portion 131 and the second portion 132 are brought into close contact with each other at least in the portion where the solvent is applied, and the solvent is removed by drying or the like while maintaining this state.

  The applied solvent penetrates into the voids of the porous sheet and melts or swells the heat resistant resin. After the application of the solvent, the close contact state between the first part 131 and the second part 132 is maintained, so that the heat-resistant resin is melted or swelled by the solvent in both the first part 131 and the second part 132. Arise. As a result, the boundary between the first portion 131 and the second portion 132 substantially disappears in the portion where the solvent is applied, and the gap also substantially disappears. As a result, as schematically shown in FIG. 7, in the joint portion 133 formed by removing the solvent, the first portion 131 and the second portion 132 do not intervene with any other members. It is configured as one layer straddling the first portion 131 and the second portion 132. That is, the joint portion 133 has a portion that straddles the first portion 131 and the second portion 132, and thereby the first portion 131 and the second portion 132 are integrated. . Moreover, in the junction part 133, the space | gap does not exist or the porosity is low compared with another part.

  On the other hand, as the bonding agent, a solution obtained by dissolving the above-described resin exemplified as the heat-resistant resin contained in the porous sheet with these solvents (hereinafter referred to as “resin solution”) can be used. Specifically, as such a solution, a solution in which a polyamide resin or an aramid resin (aromatic polyamide resin) is dissolved in NMP, a solution in which a polyphenylene sulfide resin is dissolved in diphenyl ether, NMP or N-Cyclohexylpropylone, a polysulfone resin in dichloromethane or methyl is used. A solution in which pyrrolidone is dissolved, a solution in which polyethersulfone resin is dissolved in NMP, tetremethylurea, DMAc, DMSO or DMF, a solution in which polyetherimide resin is dissolved in NMP, a polyetheretherketone resin in DMSO, DMAC, chloroform or Examples thereof include a solution in THF and a solution in which polyamideimide resin is dissolved in NMP, DMAc, DMF, or DMSO.

  Even when the resin solution is used as the bonding agent, the resin solution forms the bonding portion 133 on the opposing surfaces of at least one of the first portion 131 and the second portion 132 of the porous sheet, like the solvent. It is applied to the part to be done. In addition, the first part 131 and the second part may be brought into intimate contact with each other at least at the part where the resin solution is applied after application, and the solvent may be removed by drying or the like while maintaining this state. It is the same as the case where is used.

  However, the form of integration of the first part 131 and the second part 132 is that the solvent in the resin solution contains a heat resistant resin contained in the porous sheet constituting the first part 131 and the second part 132. It depends on whether it can be dissolved or swollen.

  When the solvent in the resin solution is a solvent that can dissolve or swell the heat-resistant resin contained in the porous sheet, the heat-resistant resin is dissolved or swollen by the resin solution. Therefore, as in the case where a solvent is used as the bonding agent, the first portion 131 and the second portion 132 are integrated by a coupling portion 133 configured as one layer straddling both.

  However, when the solvent in the resin solution is a solvent that cannot dissolve or swell the heat-resistant resin contained in the porous sheet, the applied resin solution has a gap between the first portion 131 and the second portion 132. Penetrate into. When the solvent is removed from the resin solution that has penetrated into the voids, the heat resistant resin in the resin solution remains in the voids and solidifies in the voids. As shown in FIG. 8, the portion 134 of the heat-resistant resin solidified in the gap that extends across both the first portion 131 and the second portion 132 is divided into the first portion 131 and the second portion 132. It functions as an anchor to be fixed, thereby forming a joint portion 133 in which the first portion 131 and the second portion 132 are integrated. Further, in the joint portion 133, the gap between the first portion 131 and the second portion 132 is filled with the resin contained in the resin solution, and thus the gap is not substantially present.

  As described above, the joint portion 133 between the first portion 131 and the second portion 132 is configured to include a portion that straddles the first portion 131 and the second portion 132. The first portion 131 and the second portion 132 are bonded with sufficient bonding strength. As a result, it is possible to obtain a cylindrical separator 13 that is difficult to break at the joint portion 133. By accommodating the positive electrode 12 or the negative electrode 11 in such a separator 13, misalignment between the electrode (the positive electrode 12 and the negative electrode 11) and the separator 13 from the time of manufacture of the battery to after completion of the battery is prevented. A short circuit between them can be prevented well.

  In addition, a portion of the joint portion 133 that extends across the first portion 131 and the second portion 132 is made of a resin having a melting point or glass transition temperature of 200 ° C. or higher. Therefore, for example, even when the battery becomes high temperature due to occurrence of an abnormality, the portion existing over this does not melt or soften, and the bonding state between the first portion 131 and the second portion 132 is good. Maintained.

  When applying a solvent or a resin solution to the porous sheet, the porous sheet is excellent in the permeability of the solvent or the resin solution, and the porosity of the porous sheet is lost in a region where the solvent or the resin solution has permeated. . Therefore, when there is too much application quantity of a solvent or a resin solution, there exists a possibility that the area | region where porosity may be lost will spread too much and the function as the separator 13 may be lost. Therefore, it is important that the coating amount of the solvent or resin solution is sufficiently controlled. Examples of the coating method that can manage the coating amount well include, for example, a method of transferring a solvent or a resin solution to a porous sheet using a stamp, a method of discharging a solvent or a resin solution from a fine nozzle (inkjet method), or a spray. And a method of adding a trace amount of a solvent or a resin solution with a microdispenser.

  The joint portion 133 may be partially formed or continuously formed in a linear shape as long as it is a position around the positive electrode 12 or the negative electrode 11. However, the bonding strength of the bonding portion 133 depends on the area of the bonding portion. Generally, the larger the bonding area, the higher the bonding strength is obtained, so that the separator 13 can maintain a cylindrical shape well. Therefore, it is preferable to form the joint part 133 in a linear shape. From this point of view, when the joint portion 133 is partially formed, the joint portion 133 is preferably formed in a dotted line shape. In the case where the joint portion 133 is formed in a dotted line shape, when the positive electrode 12 or the negative electrode 11 accommodated in the separator 13 is impregnated with the electrolyte solution, the electrolyte solution easily enters the separator 13 through the dotted line gap in the joint portion 133. Become. As a result, the battery manufacturing time can be shortened.

  The width of the bonding portion 133 is preferably 0.05 mm or more in order to bond the first portion 131 and the second portion 132 satisfactorily, and from the viewpoint that higher bonding strength can be obtained. More preferably, it is 0.1 mm or more. On the other hand, if the width of the joint part 133 is too wide, the area of the separator 13 becomes larger than the area of the positive electrode 12 or the negative electrode 11 to be accommodated, leading to an increase in size of the battery itself. This means that the battery capacity per unit volume is reduced or the battery capacity per unit weight is reduced. Therefore, the width of the joint portion 133 is preferably 3 mm or less, more preferably 1 mm or less.

  Here, the width of the joint portion 133 refers to a dimension in a direction perpendicular to the length direction of the joint portion 133 as viewed from the outer surface of the separator 13. The separator 13 is made of a porous sheet and has a large number of voids. However, as described above, the bonding portion 133 does not have voids or has a lower porosity than other portions. ing. Therefore, the separator 13 is configured so that the bonding portion 133 and the portion other than the bonding portion 133 are separated from each other by, for example, visual observation or enlarged observation from the outer surface of the separator 131 due to the difference in light transmittance due to the difference in porosity. Can be distinguished.

The coating amount of the solvent or resin solution for forming the joint 133 is preferably ^{0.1μL / cm 2 ~3μL / cm 2} , in particular, a thickness of 15 to 30 [mu] m, porosity of 30 to 30% when applied to the porous sheet is preferably set to ^{0.45μL / cm 2 ~2.4μL / cm 2} . According to the above-described coating method that can manage the coating amount satisfactorily, the solvent or the resin solution can be easily applied at such a coating amount. Moreover, when apply | coating by transcription | transfer, in order to apply | coat an appropriate amount of solvent or resin solution, it is preferable that the part used as the transfer surface of a stamp is comprised with a nonwoven fabric or a porous body.

  In addition, when apply | coating a solvent or a resin solution to a porous sheet, the applied solvent or resin solution actually permeates and spreads to the space | gap of a porous sheet. Therefore, in order to make the width of the joint part 133 finally obtained the preferable width as described above, the application width of the solvent or the resin solution is preferably set in consideration of the expansion. However, in the case of applying by a coating method that can manage the coating amount as described above, since the spread of the solvent or the resin solution can be suppressed to the minimum, the coating width of the solvent or the resin solution is the width of the joint portion 133. Can be considered to be substantially equal.

  After applying the solvent or the resin solution, the first portion 131 and the second portion are formed in the region where the solvent or the resin solution is applied in order to promote the bonding between the first portion 131 and the second portion 132 of the porous sheet. 132 is preferably pressurized. Further, when the region to be the joint portion 133 is pressurized while being irradiated with ultrasonic waves, the dissolved heat resistant resin (the heat resistant resin referred to here is the boundary portion between the first portion 131 and the second portion 132). It may be a heat-resistant resin contained in the porous sheet or a heat-resistant resin contained in the resin solution.

  In removing the solvent, it is preferable to heat the portion of the porous sheet coated with the solvent or the resin solution. Thereby, the removal by volatilization of a solvent is accelerated | stimulated. Moreover, when a solvent is a solvent which can melt | dissolve the heat resistant resin of a porous sheet, melt | dissolution of the porous sheet by the solvent in a solvent application part can also be accelerated | stimulated. The heating temperature of the porous sheet at this time is preferably 30 ° C. or higher, more preferably 50 ° C. or higher. The higher the heating temperature, the more the dissolution of the porous sheet is promoted. However, at a temperature close to the boiling point of the solvent, the volatility becomes too high, and the joining of the first portion 131 and the second portion 132 may be difficult. From this viewpoint, the heating temperature of the porous sheet is preferably not higher than the boiling point of the solvent, more preferably 30 ° C. or more lower than the boiling point of the solvent, more preferably 50 ° C. lower than the boiling point of the solvent. . Moreover, it is preferable to perform the heating for solvent removal under a reduced pressure environment. As a result, the vapor pressure of the solvent can be increased even at a temperature below the boiling point, and as a result, drying and removal of the solvent can be promoted without causing thermal deterioration of the heat-resistant resin and other materials.

  As a form of the porous sheet, any form such as a porous film, a fiber assembly such as a woven fabric and a non-woven fabric, and a microporous film can be adopted. Among these, a microporous film is particularly preferable because lithium is difficult to precipitate and a short circuit between the positive electrode and the negative electrode can be suppressed. In addition, it is preferable that the porous sheet has a smaller pore diameter on the negative electrode side surface because lithium deposition can be suppressed.

  The porosity of the porous sheet can be appropriately set according to the characteristics required as a palator. For example, in order to obtain good rate characteristics of the battery, the porosity is preferably 35% or more, and more preferably 40% or more. Moreover, in order to increase the mechanical strength as a separator, the porosity of the porous sheet is preferably 80% or less, and more preferably 70% or less.

  The porosity of the porous sheet can be calculated by the following formula by measuring the bulk density according to JIS P 8118.

  Other methods for measuring the porosity include a direct observation method using an electron microscope and a press-fitting method using a mercury porosimeter.

  The average pore diameter of the porous sheet is preferably 1 μm or less, more preferably 0.5 μm or less, and still more preferably 0.1 μm or less. In order to allow the charged material to permeate well, the porous sheet preferably has a void diameter on the negative electrode surface of 0.005 μm or more, more preferably 0.01 μm or more.

  As an example of the average void diameter, the average void diameter of the porous sheet is about 0.5 μm in the case of a microporous film made of an aramid resin, about 0.3 μm in the case of a microporous film made of a polyimide resin, and from a polyphenylene sulfide resin. In the case of a microporous film, it may be about 0.5 μm.

  The pore diameter of the porous sheet can be determined by the bubble point method and the mean flow method described in STM-F-316. Further, the average void diameter can be obtained by measuring the void diameter at each of five arbitrary positions of the porous sheet and averaging the measured values.

  The thickness of the porous sheet is preferably thicker from the viewpoint of maintaining insulation and mechanical strength. On the other hand, the thinner one is preferable from the viewpoint of improving the energy density of the battery. Specifically, the thickness of the porous sheet is preferably 3 μm or more, more preferably 5 μm or more, and even more preferably 8 μm or more in order to prevent a short circuit between the positive electrode and the negative electrode and to provide sufficient heat resistance. . On the other hand, the thickness of the porous sheet is preferably 40 μm or less, more preferably 30 μm or less, and even more preferably 25 μm or less in order to meet battery specifications such as normally required energy density. As an example, in any case of a microporous film made of an aramid resin, a microporous film made of a polyimide resin, and a microporous film made of a polyphenylene sulfide resin, the thickness of the porous sheet can be about 20 μm.

  The thickness Ts of the insulating layer can be used as an index indicating the insulation property of the separator at a high temperature. The porous sheet has voids, and the electrode mixture layer also has voids. The electrode and the separator may locally reach 400 ° C. due to overcharge or the like. Therefore, in this case, insulation at 400 ° C. is important. The resin that melts at 400 ° C. or less loses the insulating performance due to the loss of the separator gap. Moreover, when the molten resin enters the gaps in the electrode mixture layer, the distance between the electrodes is narrowed, and the insulating performance is lowered. The thickness (Ts) of the insulating layer at 400 ° C. is preferably 3 μm or more, more preferably 5 μm or more.

  An inorganic porous layer can be laminated on the porous sheet. An inorganic binder and an organic binder can be used for lamination of the inorganic porous layer. The inorganic binder is not particularly limited, and silica-based materials, alumina-based materials, silica-alumina-based materials, aluminum-based, aluminum phosphate-based materials, silver-based materials, and the like can be used. As the organic binder, polyvinylidene fluoride (PVdF), polyethylene oxide (PEO), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), and a copolymer of these polymers can be preferably used. For these binders, a single material may be used, or a mixture of two or more materials may be used.

Since the value of the ionic conductivity of the separator greatly affects the internal resistance value of the battery, a larger value is preferable. For example, the electrolytic solution of the lithium secondary battery is 10 ⁻³ S / cm, and it is desirable that the electrolyte is 10 ⁻⁴ to 10 ⁻⁶ S / cm when the lithium secondary battery is immersed.

(Negative electrode)
The negative electrode has a structure in which a negative electrode active material is laminated on a current collector as a negative electrode active material layer integrated with a negative electrode binder. The negative electrode active material is a material capable of reversibly receiving and releasing lithium ions with charge and discharge.

  In one embodiment of the present invention, the negative electrode includes a metal and / or a metal oxide and carbon as a negative electrode active material. Examples of the metal include Li, Al, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn, La, or alloys of two or more thereof. . Moreover, you may use these metals or alloys in mixture of 2 or more types. These metals or alloys may contain one or more non-metallic elements.

  Examples of the metal oxide include silicon oxide, aluminum oxide, tin oxide, indium oxide, zinc oxide, lithium oxide, and composites thereof. In this embodiment, it is preferable that tin oxide or silicon oxide is included as the negative electrode active material, and it is more preferable that silicon oxide is included. This is because silicon oxide is relatively stable and hardly causes a reaction with other compounds. Moreover, 0.1-5 mass% of 1 type, or 2 or more types of elements chosen from nitrogen, boron, and sulfur can also be added to a metal oxide, for example. By carrying out like this, the electrical conductivity of a metal oxide can be improved. In addition, the electrical conductivity can be similarly improved by coating a metal or metal oxide with a conductive material such as carbon by a method such as vapor deposition.

  Examples of carbon include graphite, amorphous carbon, diamond-like carbon, carbon nanotube, or a composite thereof. Here, graphite with high crystallinity has high electrical conductivity, and is excellent in adhesiveness and voltage flatness with a negative electrode current collector made of a metal such as copper. On the other hand, since amorphous carbon having low crystallinity has a relatively small volume expansion, it has a high effect of relaxing the volume expansion of the entire negative electrode, and deterioration due to non-uniformity such as crystal grain boundaries and defects hardly occurs.

  Metals and metal oxides are characterized by a lithium acceptability that is much greater than that of carbon. Therefore, the energy density of the battery can be improved by using a large amount of metal and metal oxide as the negative electrode active material. In order to achieve a high energy density, it is preferable that the content ratio of the metal and / or metal oxide in the negative electrode active material is high, and the amount of lithium contained in the negative electrode that can accept lithium is more than the amount of lithium that can be released from the positive electrode A metal and / or metal oxide is mixed in the negative electrode so as to reduce the amount. In the present specification, the amount of lithium that can be released from the positive electrode and the amount of lithium contained in the negative electrode that can accept lithium mean the respective theoretical capacities. The ratio of the lithium-acceptable amount of carbon contained in the negative electrode to the lithium-releasable amount of the positive electrode is preferably 0.95 or less, more preferably 0.9 or less, and even more preferably 0.8 or less. A larger amount of metal and / or metal oxide is preferable because the capacity of the whole negative electrode increases. The metal and / or metal oxide is preferably contained in the negative electrode in an amount of 0.01% by mass or more of the negative electrode active material, more preferably 0.1% by mass or more, and still more preferably 1% by mass or more. However, the metal and / or metal oxide has a large volume change when lithium is occluded / released compared to carbon, and the electrical connection may be lost. It is not more than mass%, more preferably not more than 80 mass%. As described above, the negative electrode active material is a material capable of reversibly receiving and releasing lithium ions in accordance with charge and discharge in the negative electrode, and does not include other binders.

  As the binder for the negative electrode, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, styrene-butadiene copolymer rubber, polytetrafluoroethylene, polypropylene, polyethylene, Acrylic, polyimide, polyamideimide and the like can be used. In addition to the above, styrene butadiene rubber (SBR) and the like can be mentioned. When an aqueous binder such as an SBR emulsion is used, a thickener such as carboxymethyl cellulose (CMC) can also be used. The amount of the negative electrode binder used is preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the negative electrode active material, from the viewpoint of sufficient binding force and high energy in a trade-off relationship. The above binder for negative electrode can also be used as a mixture.

  The negative electrode active material can be used together with a conductive auxiliary material. Specific examples of the conductive auxiliary material include the same materials as specifically exemplified in the positive electrode, and the amount of the conductive auxiliary material can be the same.

  As the negative electrode current collector, aluminum, nickel, stainless steel, chromium, copper, silver, and alloys thereof are preferable from the viewpoint of electrochemical stability. Examples of the shape include foil, flat plate, and mesh.

  A conductive auxiliary material may be added to the coating layer containing the negative electrode active material for the purpose of reducing impedance. Examples of the conductive auxiliary material include flaky carbonaceous fine particles such as graphite, carbon black, acetylene black, and vapor grown carbon fiber (VGCF (registered trademark) manufactured by Showa Denko).

  Examples of the method for forming the negative electrode active material layer include a doctor blade method, a die coater method, a CVD method, and a sputtering method. After forming a negative electrode active material layer in advance, a thin film of aluminum, nickel, or an alloy thereof may be formed by a method such as vapor deposition or sputtering to form a negative electrode current collector.

(Positive electrode)
The positive electrode means an electrode on the high potential side in the battery. As an example, the positive electrode includes a positive electrode active material capable of reversibly receiving and releasing lithium ions with charge and discharge, and the positive electrode active material is formed by a positive electrode binder. The integrated positive electrode active material layer has a structure laminated on the current collector. In one embodiment of the present invention, the positive electrode has a charge capacity per unit area of 3 mAh / cm ² or more, preferably 3.5 mAh / cm ² or more. Moreover, it is preferable that the charging capacity of the positive electrode per unit area is 15 mAh / cm ² or less from the viewpoint of safety. Here, the charge capacity per unit area is calculated from the theoretical capacity of the active material. That is, the charge capacity of the positive electrode per unit area is calculated by (theoretical capacity of the positive electrode active material used for the positive electrode) / (area of the positive electrode). In addition, the area of a positive electrode means the area of one side instead of both surfaces of a positive electrode.

In order to increase the energy density of the positive electrode, the positive electrode active material used for the positive electrode accepts and releases lithium and is preferably a compound having a higher capacity. Examples of the high-capacity compound include a lithium-nickel composite oxide obtained by substituting a part of Ni of lithium lithium oxide (LiNiO ₂ ) with another metal element, and a layered lithium-nickel composite oxide represented by the following formula (A): Things are preferred.

Li _y Ni _(1-x) M _x O ₂ (A)
(However, 0 ≦ x <1, 0 <y ≦ 1.2, and M is at least one element selected from the group consisting of Co, Al, Mn, Fe, Ti, and B.)

From the viewpoint of high capacity, the Ni content is high, that is, in the formula (A), x is preferably less than 0.5, and more preferably 0.4 or less. Examples of such a compound include Li _α Ni _β Co _γ Mn _δ O ₂ (0 <α ≦ 1.2, preferably 1 ≦ α ≦ 1.2, β + γ + δ = 1, β ≧ 0.7, γ ≦ 0. .2), Li _α Ni _β Co _γ Al _δ O ₂ (0 <α ≦ 1.2, preferably 1 ≦ α ≦ 1.2, β + γ + δ = 1, β ≧ 0.6, preferably β ≧ 0.7, γ ≦ 0.2), etc., especially LiNi _β Co _γ Mn _δ O ₂ (0.75 ≦ β ≦ 0.85, 0.05 ≦ γ ≦ 0.15, 0.10 ≦ δ ≦ 0.20). ). More specifically, for example, LiNi _0.8 Co _0.05 Mn _0.15 O ₂ , LiNi _0.8 Co _0.1 Mn _0.1 O ₂ , LiNi _0.8 Co _0.15 Al _0.05 O _{2, LiNi} 0.8 _Co 0.1 _Al can be preferably used 0.1 _{O 2} or the like.

From the viewpoint of thermal stability, it is also preferable that the Ni content does not exceed 0.5, that is, in the formula (A), x is 0.5 or more. It is also preferred that the number of specific transition metals does not exceed half. Such compounds include Li _α Ni _β Co _γ Mn _δ O ₂ (0 <α ≦ 1.2, preferably 1 ≦ α ≦ 1.2, β + γ + δ = 1, 0.2 ≦ β ≦ 0.5, 0 0.1 ≦ γ ≦ 0.4, 0.1 ≦ δ ≦ 0.4). More specifically, LiNi _0.4 Co _0.3 Mn _0.3 O ₂ (abbreviated as NCM433), LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , LiNi _0.5 Co _0.2 Mn _0.3 O ₂ (abbreviated as NCM523), LiNi _0.5 Co _0.3 Mn _0.2 O ₂ (abbreviated as NCM532), etc. (however, the content of each transition metal in these compounds varies by about 10%) Can also be included).

  In addition, two or more compounds represented by the formula (A) may be used as a mixture. For example, NCM532 or NCM523 and NCM433 may be used in a range of 9: 1 to 1: 9 (typically 2 It is also preferable to use a mixture in 1). Furthermore, in the formula (A), a material having a high Ni content (x is 0.4 or less) and a material having a Ni content not exceeding 0.5 (x is 0.5 or more, for example, NCM433) are mixed. As a result, a battery having a high capacity and high thermal stability can be formed.

Other than the above, as the positive electrode active material, for example, LiMnO ₂ , Li _x Mn ₂ O ₄ (0 <x <2), Li ₂ MnO ₃ , Li _x Mn _1.5 Ni _0.5 O ₄ (0 <x < 2) Lithium manganate having a layered structure or spinel structure such as LiCoO ₂ or a part of these transition metals replaced with another metal; Li in these lithium transition metal oxides more than the stoichiometric composition And those having an olivine structure such as LiFePO ₄ . Furthermore, a material in which these metal oxides are partially substituted with Al, Fe, P, Ti, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn, La, etc. Can also be used. Any of the positive electrode active materials described above can be used alone or in combination of two or more.

  As the positive electrode binder, the same negative electrode binder can be used. Among these, from the viewpoint of versatility and low cost, polyvinylidene fluoride or polytetrafluoroethylene is preferable, and polyvinylidene fluoride is more preferable. The amount of the binder for the positive electrode to be used is preferably 2 to 10 parts by mass with respect to 100 parts by mass of the positive electrode active material from the viewpoints of “sufficient binding force” and “high energy” which are in a trade-off relationship. .

  A conductive auxiliary material may be added to the coating layer containing the positive electrode active material for the purpose of reducing impedance. Examples of the conductive auxiliary material include flaky carbonaceous fine particles such as graphite, carbon black, acetylene black, vapor grown carbon fiber (for example, VGCF manufactured by Showa Denko).

  As the positive electrode current collector, the same as the negative electrode current collector can be used. In particular, the positive electrode is preferably a current collector using aluminum, an aluminum alloy, or iron / nickel / chromium / molybdenum stainless steel.

  Similarly to the negative electrode, the positive electrode can be produced by forming a positive electrode active material layer containing a positive electrode active material and a positive electrode binder on a positive electrode current collector.

(Electrolyte)
Although it does not specifically limit as electrolyte solution of the lithium ion secondary battery which concerns on this embodiment, The nonaqueous electrolyte solution containing the nonaqueous solvent and supporting salt which are stable in the operating potential of a battery is preferable.

  Examples of non-aqueous solvents include propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC) and other cyclic carbonates; dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), Chain carbonates such as dipropyl carbonate (DPC); propylene carbonate derivatives, aliphatic carboxylic acid esters such as methyl formate, methyl acetate and ethyl propionate; ethers such as diethyl ether and ethyl propyl ether; trimethyl phosphate; Aprotic organic solvents such as phosphate esters such as triethyl phosphate, tripropyl phosphate, trioctyl phosphate and triphenyl phosphate, and fluorine in which at least some of the hydrogen atoms of these compounds are substituted with fluorine atoms Aprotic organic solvents, and the like.

  In a secondary battery including a metal or a metal oxide in a negative electrode, they may deteriorate and collapse, thereby increasing the surface area and promoting the decomposition of the electrolytic solution. The gas generated by the decomposition of the electrolyte is one of the factors that hinder the reception of lithium ions in the negative electrode. For this reason, in the lithium ion secondary battery in which the content ratio of the metal and / or metal oxide in the negative electrode is large as in the present invention, a solvent having high oxidation resistance and being difficult to decompose is preferable. Examples of the solvent having strong oxidation resistance include fluorinated aprotic organic solvents such as fluorinated ethers and fluorinated phosphates.

  In addition, cyclic or ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (MEC), dipropyl carbonate (DPC), etc. Chain carbonates are also mentioned as particularly preferred solvents.

  A nonaqueous solvent can be used individually by 1 type or in combination of 2 or more types.

The supporting salts include LiPF ₆ , LiAsF ₆ , LiAlCl ₄ , LiClO ₄ , LiBF ₄ , LiSbF ₆ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiN (CF ₃ SO ₂ ) A lithium salt such as ₂ . The supporting salt can be used singly or in combination of two or more. LiPF ₆ is preferable from the viewpoint of cost reduction.

  The electrolytic solution can further contain an additive. Although it does not specifically limit as an additive, A halogenated cyclic carbonate, an unsaturated cyclic carbonate, cyclic | annular or chain | strand-shaped disulfonic acid ester, etc. are mentioned. By adding these compounds, battery characteristics such as cycle characteristics can be improved. This is presumed to be because these additives decompose during charging / discharging of the lithium ion secondary battery to form a film on the surface of the electrode active material and suppress decomposition of the electrolytic solution and the supporting salt.

  Next, a manufacturing method and application examples of the above-described battery will be described.

[Method for producing secondary battery]
The laminated laminate type lithium ion secondary battery described above can be manufactured, for example, as follows. First, a plurality of positive electrodes 12 and a plurality of negative electrodes 11 are produced as described above.

  Next, a separator with a positive electrode in which the positive electrode 12 is accommodated in a cylindrical separator 13 in a dry air or an inert atmosphere is produced. As described above, the separator with the positive electrode is manufactured by arranging the positive electrode 12 between the first portion 131 and the second portion 132 and then joining the first portion 131 and the second portion 132 to each other. Can be produced. In this case, the joint 133 may be formed over the entire circumference of the positive electrode 12 except for a portion where the positive electrode tab 10 b extends from the separator 13. Alternatively, after manufacturing the cylindrical separator 13 in which the first part 131 and the second part 132 are joined on two or three sides, the positive electrode 12 is inserted into the separator 13, whereby the positive electrode separator is It can also be produced. In this case, after the positive electrode 12 is inserted into the separator 13, the positive electrode tab 10 b extends from the separator 13 by bonding the first portion 131 and the second portion 132 with the remaining unbonded sides. The joint 133 can be formed over the entire circumference of the positive electrode 12 except for.

  A plurality of positive electrode-containing separators are produced as described above, and these are alternately overlapped with the negative electrode 11. At this time, the orientation of the positive electrode separator and the negative electrode 11 is aligned for each negative electrode 11 and for each positive electrode separator, the extensions of the negative electrode 11 and the extensions of the positive electrode 12 are joined, and the negative electrode tab 10a and the positive electrode tab 10b are joined. Form. Thereby, the electrode laminated body 10 by which the some positive electrode 12 and the some negative electrode 11 were laminated | stacked via the separator 13 is produced. The number of stacked positive electrodes 12 and negative electrodes 11 is determined according to the target battery capacity. In the above example, only the positive electrode 12 is housed in the separator 13, but only the negative electrode 11 can be housed in the separator 13.

  Next, the negative electrode terminal 31 is bonded to the negative electrode tab 10a, and the positive electrode terminal 32 is bonded to the positive electrode end portion 10b. After these terminals are joined, the electrode laminate 10 is housed in an exterior body. When a laminate film is used as the outer package, the electrode laminate 10 can be accommodated in the outer package by heat-sealing the laminate film around the electrode laminate 10. At this time, the negative electrode detection 31 and the positive electrode terminal 32 are made to protrude from the exterior body. Also, the laminate film is heat-sealed leaving a portion that becomes an opening for injecting the electrolyte in a later step.

  After the electrode laminate 10 is stored in the outer package, an electrolytic solution is injected from the opening of the outer package, and the electrode laminate 10 is impregnated with the electrolyte. Then, an opening part is enclosed and a secondary battery is manufactured by this.

  The battery having the laminated structure described above is one of the preferable modes in which a great effect can be obtained by the present invention because the separator is easily deformed or displaced due to thermal shrinkage when a general separator is used.

[Battery]
A plurality of secondary batteries can be combined to form an assembled battery. For example, the assembled battery may have a configuration in which two or more secondary batteries according to the present embodiment are connected in series and / or in parallel. The series number and the parallel number of secondary batteries can be appropriately selected according to the intended voltage and capacity of the assembled battery.

[vehicle]
The secondary battery or its assembled battery described above can be used for a vehicle. Vehicles that can use secondary batteries or assembled batteries include hybrid vehicles, fuel cell vehicles, and electric vehicles (all are four-wheeled vehicles (passenger cars, commercial vehicles such as trucks and buses, light vehicles, etc.), and motorcycles (motorcycles). And tricycles). Note that the vehicle according to the present embodiment is not limited to an automobile, and may be used as various power sources for other vehicles, for example, moving bodies such as trains. As an example of such a vehicle, FIG. 9 shows a schematic diagram of an electric vehicle. An electric vehicle 200 shown in FIG. 9 includes an assembled battery 210 configured to connect a plurality of the above-described secondary batteries in series and in parallel to satisfy a required voltage and capacity.

[Power storage device]
The secondary battery or the assembled battery described above can be used for a power storage device. As a power storage device using a secondary battery or an assembled battery, for example, it is connected between a commercial power source supplied to a general household and a load such as a home appliance, and is used as a backup power source or an auxiliary power source at the time of a power failure, etc. And those that are also used for large-scale power storage, such as solar power generation, for stabilizing power output with large temporal fluctuations due to renewable energy. An example of such a power storage device is schematically shown in FIG. A power storage device 300 illustrated in FIG. 10 includes an assembled battery 310 configured to connect a plurality of the above-described secondary batteries in series and in parallel to satisfy a required voltage and capacity.

[Others]
Further, the above-described secondary battery or its assembled battery can be used as a power source for mobile devices such as mobile phones and notebook computers.

  Hereinafter, the present invention will be specifically described by way of examples.

[Example 1]
(Preparation of positive electrode)
Layered lithium nickel composite oxide (LiNi _0.8 Co _1.5 Al _0.05 O ₂ ), carbon black (trade name: “# 3030B”, manufactured by Mitsubishi Chemical Corporation), and polyvinylidene fluoride (trade name: “W # 7200” (manufactured by Kureha Co., Ltd.) was weighed at a mass ratio of 93: 2: 5. These and N-methylpyrrolidone (NMP) were mixed to form a slurry. The mass ratio of NMP to solid content was 54:46. This slurry was applied as a positive electrode active material to a 15 μm thick aluminum foil (positive electrode current collector) using a doctor blade. The aluminum foil coated with this slurry was heated at 120 ° C. for 5 minutes to dry the NMP, thereby producing a positive electrode.

(Preparation of negative electrode)
A 1% by mass aqueous solution of artificial graphite and carboxymethylcellulose (CMC) is kneaded using a rotation / revolution mixer (Shinky Corporation Awatori Rentaro ARE-500), and then a styrene-butadiene copolymer (SBR) is added. A negative electrode slurry was prepared. The mass ratio of artificial graphite, CMC, and SBR was 97: 1: 2. This slurry was applied as a negative electrode active material on a copper foil (negative electrode current collector) having a thickness of 10 μm with a doctor blade, and then dried by heating at 110 ° C. for 5 minutes to produce a negative electrode.

(Preparation of separator)
For the separator, a single-layer wholly aromatic polyamide (aramid) microporous membrane was used as the porous sheet. This aramid microporous membrane had a thickness of 25 μm, an average pore diameter of 0.5 μm, and a porosity of 60%. The aramid microporous membrane was cut into a rectangular shape and two sheets were stacked. Next, the two stacked aramid microporous membranes are placed on a hot plate at 80 ° C., and the filter paper impregnated with NMP is folded and pressed along the three sides of the peripheral portion of the aramid microporous membrane to transfer the NMP. did. It was confirmed by a gravimetric method that the amount of NMP applied was 1.0 μL / cm ² in a transfer test at normal temperature without using a hot plate. The aramid microporous membrane was left on the hot plate for 1 hour. As a result, a bag-like separator was obtained in which the joining portion in which the two aramid microporous membranes were integrated at the portion where the NMP was transferred was formed linearly along the three sides of the aramid microporous membrane. In addition, when the weight of the obtained separator was measured, it confirmed that NMP was dried and lost. Moreover, the width | variety of the obtained junction part was 0.1 mm. Furthermore, about the obtained separator, joining property was evaluated by confirming a junction part visually.

  Moreover, the obtained separator was heated for 10 minutes on a 200 degreeC hotplate in order to confirm the heat resistance and shrinkage | contraction property of a junction part. About the separator after a heating, heat resistance evaluation and shrinkage | contraction evaluation were performed by confirming the presence or absence of the peeling in a junction part, and the presence or absence of shrinkage visually.

(Production of secondary battery)
Next, a plurality of positive electrodes were cut out so as to have an uncoated portion of the positive electrode active material to be a positive electrode tab. Each of the cut out positive electrodes was stored one by one in a bag-shaped separator in dry air or an inert atmosphere. Regarding the negative electrode, similarly to the positive electrode, a plurality of negative electrodes were cut out so as to have an uncoated portion of the negative electrode active material to be a negative electrode tab. A plurality of positive electrodes and a plurality of negative electrodes stored in the separator were alternately overlapped so that the uncoated portions of the respective active materials were in opposite directions to form an electrode laminate. The uncoated portions of the positive electrode active material of the positive electrode were collectively joined to the positive electrode terminal, and the uncoated portions of the negative electrode active material of the negative electrode were collectively joined to the negative electrode terminal. Next, this electrode laminated body was accommodated in an exterior body (container), a nonaqueous electrolytic solution was injected, and the electrode laminated body was impregnated with the electrolytic solution. As the electrolytic solution, a solution containing 1.0 mol / l LiPF ₆ as an electrolyte and a mixed solvent of ethylene carbonate and diethyl carbonate (7: 3 (volume ratio)) as a nonaqueous electrolytic solvent was used. Then, the opening part of the exterior body was sealed and the secondary battery was completed.

  The secondary battery manufactured as described above was vibrated. The vibration was a sweep vibration that returned to 7 Hz via a frequency of 7 Hz through 200 Hz in 15 minutes, and this was performed for 12 sets in each of the three directions of X, Y, and Z. After the battery was vibrated, the initial discharge capacity was measured. The conditions for the initial charge / discharge were a 0.05C current, 20 ° C environment, a 4.2V upper limit, and a 2.5V lower limit. At this time, those that could not be charged due to a short circuit were counted as a short circuit after the vibration test.

[Example 2]
A secondary battery was produced in the same manner as in Example 1 except that an NMP solution in which 10% by mass of aramid resin was dissolved was used to join the porous sheets in the production of the separator. went.

[Example 3]
A polyimide microporous film (thickness 20 μm, average void diameter 0.3 μm, porosity 80%) was used as the porous sheet, and the coating amount of the solution applied to form a bag-like joint was 3 μL / cm. ^A secondary battery was produced in the same manner as in Example 2 except that the value was set to 2, and the same evaluation as in Example 1 was performed.

[Example 4]
A secondary battery was prepared in the same manner as in Example 2 except that a polyphenylene sulfide microporous membrane (thickness 20 μm, average void diameter 0.5 μm, porosity 40%) was used as the porous sheet. Evaluation was performed.

[Example 5]
A secondary battery was produced in the same manner as in Example 1 except that the temperature of the hot plate used for bonding the porous sheets was 120 ° C., and the same evaluation as in Example 1 was performed.

[Example 6]
A secondary battery was produced in the same manner as in Example 3 except that the temperature of the hot plate used for joining the porous sheets was 120 ° C., and the same evaluation as in Example 1 was performed.

[Example 7]
A secondary battery was produced in the same manner as in Example 1 except that the amount of NMP used for joining the porous sheets was 10 μL / cm ² , and the same evaluation as in Example 1 was performed. Since wrinkles were generated in the joined portion of the porous sheet, workability was poor, and it took twice as long as in Example 1 to store the positive electrode.

[Comparative Example 1]
A polyimide microporous film (thickness 20 μm, average void diameter 0.3 μm, porosity 80%) is used as the porous sheet, and the amount of NMP applied to form a bag-like joint is 3 μL / cm. ^A secondary battery was produced in the same manner as in Example 1 except that the value was set to ² , and the same evaluation as in Example 1 was performed. However, since the porous sheet was not joined and a bag-like separator could not be obtained, the positive electrode and the negative electrode were alternately laminated, and each tab was joined to the electrode terminal. An electrode laminate was formed by sandwiching.

[Comparative Example 2]
A secondary battery was produced in the same manner as in Example 1 except that ethanol was used to join the porous sheets in the production of the separator, and the same evaluation as in Example 1 was performed. However, since the porous sheet was not joined and a bag-like separator could not be obtained, the positive electrode and the negative electrode were alternately laminated, and each tab was joined to the electrode terminal. A laminated body was formed by sandwiching.

[Comparative Example 3]
A secondary battery was produced in the same manner as in Example 1 except that a toluene solution in which 10% by mass of polystyrene resin was dissolved was used to join the porous sheets in the production of the separator. went.

  Table 1 shows the main production conditions of the separator, the evaluation result of the joint portion of the porous sheet, and the vibration test result of the obtained secondary battery for Examples 1 to 7 and Comparative Examples 1 to 3. In Table 1, the evaluation results for bondability are represented by “◯” for those where no peeling occurs and “X” for those where peeling occurs. The evaluation results of the heat resistance of the joint were represented by “◯” for those in which no peeling occurred and “×” for those in which peeling occurred. The evaluation results for shrinkage are “O” when there was no change in appearance such as wrinkles due to shrinkage or deformation of the separator before and after heating, and there was no shrinkage but wrinkles around the joint. What was recognized was represented by “Δ”, and those in which changes in appearance were observed before and after heating, such as generation of wrinkles other than the joints and deformation of the separator, were represented by “x”.

  In Examples 1, 5 and 7, the microporous membrane made of aramid was used as a porous sheet, and NMP capable of dissolving aramid was used as a bonding agent, thereby forming a bag shape. Processing was done. However, in Example 5, since the temperature at the time of joining was high, the drying was quick, but the solubility was high, resulting in poor uniform joining properties. In addition, since an excessive amount of NMP was used in Example 7, the bonding agent could not be applied to the microporous membrane with high impregnation property in a uniform linear shape, and was in a bowl shape as compared with Examples 1 and 5. A joint with a spread was formed. On the other hand, in Comparative Example 1, NMP was used as the bonding agent, but a microporous film made of polyimide was used as the porous sheet. Since polyimide did not dissolve or swell in NMP, as a result, the polyimide microporous film could not be bonded.

  In Examples 2, 3, 4 and 6, an aramid solution was used as a bonding agent. The aramid solution does not dissolve the polyimide microporous film used as the porous sheet in Examples 3 and 6. However, since the aramid resin that penetrated into the voids of the polyimide microporous membrane functions as an anchor, the polyimide microporous membrane could be processed into a bag shape. Further, since the aramid resin is a heat-resistant resin, no peeling occurred at the joint even when heated to 200 ° C. Therefore, it can be expected that safety can be ensured even when the battery is placed in an abnormally high temperature environment.

  In Example 6, as in Example 5, bonding was performed at a high temperature of 120 ° C. However, since the polyimide microporous film used in Example 6 was not dissolved in the NMP solvent, wrinkles did not occur in the bonded portion.

  In Comparative Example 2, ethanol was used as a bonding agent. Similar to Comparative Example 1, since the aramid microporous membrane used as the porous sheet in Comparative Example 2 did not dissolve in ethanol, the aramid microporous membrane could not be processed into a bag shape. In Comparative Example 3, a toluene solution of polystyrene resin was used as a bonding agent. Although the aramid microporous membrane used as the porous sheet in Comparative Example 3 does not dissolve in toluene, since the polystyrene resin functions as an anchor, it was possible to join the aramid microporous membrane. However, there was no heat resistance at 200 ° C., and peeling of the joint occurred. In addition, since polystyrene resin is soluble in the electrolytic solution, it was often peeled off during the vibration test.

  As mentioned above, although this invention was demonstrated in detail by embodiment and the Example, this specification discloses the following invention.

[1] A battery separator 13 in which a positive electrode 12 and a negative electrode 11 are arranged to face each other,
One folded bi-fold sheet containing a resin having a melting point or glass transition temperature of 200 ° C. or higher, having a first part 131 and a second part 132 arranged opposite to each other, or superposed Having two porous sheets,
The porous sheet is formed by a joint portion 133 that has a portion that straddles the first portion 131 and the second portion 132 and integrates the first portion 131 and the second portion 132. However, the separator 13 is formed in a cylindrical shape that can accommodate the positive electrode 12 or the negative electrode 11 of the battery.

  [2] The separator 13 according to [1], wherein the porous sheet further contains an inorganic filler.

  [3] The separator according to [1] or [2], wherein the porous sheet is a microporous film having an average pore diameter of 1 μm or less.

  [4] The joint portion 133 is configured as one layer straddling the first portion 131 and the second portion 132, whereby the first portion 131 and the second portion 132 are integrated. The separator according to any one of [1] to [3].

  [5] Melting point or glass filling the gap between the first part 131 and the second part 132 across the first part 131 and the second part 132 at the joint 133. The separator according to any one of [1] to [3], wherein the first portion 131 and the second portion 132 are integrated by an anchor made of a resin having a transition temperature of 200 ° C. or higher.

  [6] The separator according to [5], wherein the resin constituting the anchor is a resin different from the resin contained in the porous sheet.

  [7] The separator according to any one of [1] to [6], wherein the porosity at the joint 133 is lower than the porosity at other than the joint.

  [8] The separator according to [7], wherein no gap exists in the joint portion 133.

  [9] The separator according to any one of [1] to [8], wherein the resin contained in the porous sheet is a wholly aromatic polyamide resin, a polyimide resin, or a polyphenylene sulfide resin.

[10] A positive electrode 12 and a negative electrode 11 which are disposed to face each other,
The separator 13 according to any one of [1] to [9];
Have
A battery in which the positive electrode 12 or the negative electrode 11 is accommodated in the separator 13.

[11] A method for producing a battery separator 13 in which a positive electrode 12 and a negative electrode 11 are arranged to face each other,
One or two porous sheets containing a resin having a melting point or a glass transition temperature of 200 ° C. or more, and are formed into a first part 131 and a second part 132 that face each other by being folded in half Preparing two porous sheets constituting the first portion 131 and the second portion 132 that are opposed to each other by being superposed, or
Using a bonding agent containing a solvent capable of melting or swelling a resin having a melting point or glass transition temperature of 200 ° C. or higher, a cylindrical body capable of accommodating the positive electrode 12 or the negative electrode 11 of the battery is formed. The joining portion 133 that integrates the first portion 131 and the second portion 132 is formed so as to have a portion that straddles the first portion 131 and the second portion 132. Process,
The manufacturing method of the separator which has this.

[12] The step of forming the joint portion 133 includes:
Superimposing the first portion 131 and the second portion 132 on each other;
The solvent that can melt or swell the resin contained in the porous sheet is used as the bonding agent, and is applied to a region to be the bonding portion 133 of at least one of the first portion 131 and the second portion 132. And a process of
Removing the solvent after the first portion 131 and the second portion 132 are overlapped with each other and the bonding agent is applied;
The method for producing a separator according to [11], comprising:

[13] The step of forming the joint portion 133 includes:
Obtaining a solution obtained by dissolving a resin having a melting point or glass transition temperature of 200 ° C. with a solvent as the bonding agent;
Superimposing the first portion 131 and the second portion 132 on each other;
Applying the bonding agent to a region to be the bonding portion 133 of at least one of the first portion 131 and the second portion 132;
Removing the solvent from the bonding agent after the first portion 131 and the second portion 132 are overlapped with each other and the bonding agent is applied;
The method for producing a separator according to [11], comprising:

  [14] The separator production method according to [13], wherein the solvent contained in the bonding agent is a solvent capable of melting or swelling the resin contained in the porous sheet.

  [15] The resin contained in the bonding agent is a resin different from the resin contained in the porous sheet, and the solvent contained in the bonding agent can melt or swell the resin contained in the bonding agent. However, the method for producing a separator according to [13], wherein the resin contained in the porous sheet cannot melt or swell.

  [16] In the step of applying the bonding agent, the first portion 131 and the second portion 132 are opposed to each other before the first portion 131 and the second portion 132 are overlapped with each other. The method for producing a separator according to any one of [12] to [15], comprising applying the bonding agent to at least one of the surfaces.

  [17] In the step of applying the bonding agent, after the first portion 131 and the second portion 132 are overlapped, the outer portion of at least one of the first portion 131 and the second portion 132 is removed. The manufacturing method of the separator in any one of [12] to [15] including applying the bonding agent on the surface.

  [18] In the step of applying the bonding agent, the porous material impregnated with the bonding agent is pressed against the region to be the bonding portion 133, thereby transferring the bonding agent to the region to be the bonding portion 133. The manufacturing method of the separator in any one of [12] to [17] containing.

  [19] The method for manufacturing a separator according to any one of [12] to [18], wherein the step of removing the solvent includes heating the first portion 131 and the second portion 132.

  [20] The method for producing a separator according to any one of [12] to [19], wherein the step of removing the solvent is performed under reduced pressure.

[21] A porous sheet containing a resin having a melting point or a glass transition temperature of 200 ° C. or higher, and is formed of one sheet constituting the first part 131 and the second part that are opposed to each other by being folded in half. Preparing a porous sheet, or two porous sheets constituting the first portion 131 and the second portion 132 facing each other by being superimposed, the positive electrode 12 and the negative electrode 11;
Disposing the positive electrode 12 or the negative electrode 11 between the first portion 131 and the second portion 132;
Using a bonding agent containing a solvent capable of melting or swelling a resin having a melting point or glass transition temperature of 200 ° C. or higher, a cylindrical body that can accommodate the positive electrode 12 or the negative electrode 11 is formed. Forming a joint 133 that integrates the first portion 131 and the second portion 132 with a portion that extends across the first portion 131 and the second portion 132; When,
The positive electrode 12 or the negative electrode 11 is disposed between the first portion 131 and the second portion 132, and the cylindrical body is formed by the first portion 131 and the second portion 132. A step of obtaining an electrode laminate 10 by laminating the positive electrode 12 and the negative electrode 11 after being formed;
Encapsulating the electrode laminate 10 together with an electrolyte in an exterior body;
The manufacturing method of the battery which has this.

  The present invention can be used in all industrial fields that require a power source, as well as industrial fields related to the transport, storage and supply of electrical energy. Specifically, power supplies for mobile devices such as mobile phones and notebook computers; power supplies for transportation and transportation media such as trains, satellites, and submarines, including electric vehicles such as electric cars, hybrid cars, electric bikes, and electric assist bicycles A backup power source such as a UPS; a power storage facility for storing power generated by solar power generation, wind power generation, etc .;

DESCRIPTION OF SYMBOLS 1 Secondary battery 10 Electrode element 11 Negative electrode 12 Positive electrode 13 Separator 21, 22 Exterior material 31 Negative electrode terminal 32 Positive electrode terminal

Claims (21)

A separator for a battery in which a positive electrode and a negative electrode are arranged opposite to each other,
One porous sheet that is folded in half, or two sheets that are superposed, containing a resin having a melting point or a glass transition temperature of 200 ° C. or more, having a first part and a second part that are arranged opposite to each other Having a porous sheet of
The porous sheet is formed by joining the first part and the second part, the part having a part that extends over the first part and the second part. A separator formed in a cylindrical shape that can accommodate a positive electrode or a negative electrode.   The separator according to claim 1, wherein the porous sheet further contains an inorganic filler.   The separator according to claim 1, wherein the porous sheet is a microporous film having an average pore diameter of 1 μm or less.   The said joint part is comprised as one layer straddling the said 1st part and the said 2nd part, and, thereby, the said 1st part and the said 2nd part are integrated. The separator according to any one of 3.   Resin having a melting point or a glass transition temperature of 200 ° C. or more filling the gap between the first part and the second part across the first part and the second part at the joint. The separator according to any one of claims 1 to 3, wherein the first portion and the second portion are integrated with each other by an anchor made of the following.   The separator according to claim 5, wherein the resin constituting the anchor is a resin different from the resin contained in the porous sheet.   The separator as described in any one of Claim 1 to 6 whose porosity in the said junction part is lower than the porosity in other than the said junction part.   The separator according to claim 7, wherein no gap exists in the joint portion.   The separator according to any one of claims 1 to 8, wherein the resin contained in the porous sheet is a wholly aromatic polyamide resin, a polyimide resin, or a polyphenylene sulfide resin. A positive electrode and a negative electrode arranged opposite to each other;
A separator according to any one of claims 1 to 9,
Have
A battery in which the positive electrode or the negative electrode is housed in the separator. A method for producing a separator for a battery in which a positive electrode and a negative electrode are disposed opposite to each other,
1 or 2 porous sheets containing a resin having a melting point or a glass transition temperature of 200 ° C. or higher, which are folded in half to constitute a first part and a second part that face each other Preparing two porous sheets constituting the first part and the second part facing each other by being laminated, or
Using a bonding agent containing a solvent capable of melting or swelling a resin having a melting point or glass transition temperature of 200 ° C. or higher, a cylindrical body that can accommodate the positive electrode or the negative electrode of the battery is formed. Forming a joining portion that integrates the first portion and the second portion with a portion that straddles the first portion and the second portion; and
The manufacturing method of the separator which has this. The step of forming the joint portion includes:
Superimposing the first part and the second part on each other;
Applying a solvent capable of melting or swelling the resin contained in the porous sheet as the bonding agent to a region to be the bonding portion of at least one of the first portion and the second portion; ,
Removing the solvent after the first part and the second part are overlapped with each other and the bonding agent is applied;
The manufacturing method of the separator of Claim 11 which has these. The step of forming the joint portion includes:
Obtaining a solution obtained by dissolving a resin having a melting point or glass transition temperature of 200 ° C. with a solvent as the bonding agent;
Superimposing the first part and the second part on each other;
Applying the bonding agent to a region to be the bonding portion of at least one of the first portion and the second portion;
Removing the solvent from the bonding agent after the first portion and the second portion are overlapped with each other and the bonding agent is applied;
The manufacturing method of the separator of Claim 11 which has these.   The method for producing a separator according to claim 13, wherein the solvent contained in the bonding agent is a solvent capable of melting or swelling the resin contained in the porous sheet.   The resin contained in the bonding agent is a resin different from the resin contained in the porous sheet, and the solvent contained in the bonding agent can melt or swell the resin contained in the bonding agent. The method for producing a separator according to claim 13, wherein the resin contained in the porous sheet cannot be melted or swollen.   The step of applying the bonding agent includes the step of applying the bonding to at least one of the opposing surfaces of the first portion and the second portion before overlapping the first portion and the second portion. The manufacturing method of the separator as described in any one of Claim 12 to 15 including apply | coating an agent.   The step of applying the bonding agent includes applying the bonding agent to the outer surface of at least one of the first portion and the second portion after the first portion and the second portion are overlapped. The manufacturing method of the separator as described in any one of Claim 12 to 15 including doing.   The step of applying the bonding agent includes transferring the bonding agent to the region to be the bonding portion by pressing the porous body impregnated with the bonding agent against the region to be the bonding portion. The manufacturing method of the separator as described in any one of 12 to 17.   The method for manufacturing a separator according to any one of claims 12 to 18, wherein the step of removing the solvent includes heating the first portion and the second portion.   The method for producing a separator according to any one of claims 12 to 19, wherein the step of removing the solvent is performed under reduced pressure. A porous sheet containing a resin having a melting point or a glass transition temperature of 200 ° C. or higher, and is formed of a single porous sheet constituting a first part and a second part facing each other by being folded in two; Or a step of preparing two porous sheets, a positive electrode and a negative electrode constituting the first part and the second part facing each other by being superposed,
Disposing the positive electrode or the negative electrode between the first portion and the second portion;
The cylindrical body that can accommodate the positive electrode or the negative electrode is formed using a bonding agent containing a solvent capable of melting or swelling a resin having a melting point or a glass transition temperature of 200 ° C. or higher. Forming a joint that integrates the first portion and the second portion with a portion that extends across the first portion and the second portion; and
After the positive electrode or the negative electrode is disposed between the first portion and the second portion, and the cylindrical body is formed by the first portion and the second portion, Obtaining an electrode laminate by laminating a positive electrode and the negative electrode;
Encapsulating the electrode laminate together with an electrolyte in an exterior body;
The manufacturing method of the battery which has this.

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