JP2007257848A - Nonaqueous secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery capable of preventing a short circuit occurring at the end face of the peripheral part of an active material layer and improving safety, in the nonaqueous electrolyte battery having a positive electrode sheet in which a positive electrode active material containing layer is formed on a current collector, a negative electrode sheet in which a negative electrode active material containing layer is formed on the current collector, and a separator interposed between the positive electrode sheet and the negative electrode sheet. <P>SOLUTION: The end face of at least one of the peripheral part of the positive electrode active material containing layer 4 and the negative electrode active material containing layer 7 is covered by an insulating resin film 10 which is a resin film having a thermal resistant resin with thermal resistant temperature of 150°C or more as a base body and contains a thermoplastic resin inside. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a non-aqueous electrolyte secondary battery, and more particularly to a non-aqueous electrolyte secondary battery suitable for use as a power source for portable electronic devices, electric vehicles, electric assist bicycles, electric motorcycles, road leveling and the like. Is.

  A lithium ion secondary battery, which is a type of nonaqueous electrolyte battery, is widely used as a power source for portable devices such as mobile phones and notebook personal computers because of its high energy density. In addition, the importance of secondary batteries that can be repeatedly charged is increasing due to considerations for environmental issues. In addition to portable devices, application to automobiles, electric chairs, household and commercial power storage systems is being considered. Yes.

  2. Description of the Related Art In recent years, hybrid vehicles (HEV) using batteries and gasoline in combination, assist bicycles that support power with batteries, electric vehicles and motorcycles that use batteries for all power have become widespread due to environmental problems. Compared to the power sources of small portable devices such as mobile phones, these medium and large power sources require high-power secondary batteries with a large capacity.

  Lithium ion batteries include cylindrical batteries and laminated batteries. A laminated battery having an energy density per weight higher than that of a cylindrical battery uses a laminated sheet obtained by laminating and integrating a metal sheet on a pair of insulating resin films as an outer case. This battery has a large degree of freedom in size and thickness, and various shapes have been conventionally made. Usually, a positive electrode lead terminal and a negative electrode lead terminal are welded to the positive electrode sheet and the negative electrode sheet, and the positive electrode sheet and the negative electrode sheet are laminated through a separator to form a laminated body of electrodes. The laminate type battery is configured by being enclosed in the laminate sheet exterior body in a state where the negative electrode lead terminal and the negative electrode lead terminal are drawn out through the seal portion of the laminate sheet. A laminate sheet is formed by laminating a heat-fusible resin layer (for example, polyethylene) on one side of a metal sheet (for example, aluminum) and a resin layer (for example, polyethylene terephthalate) having excellent mechanical strength on the other side. The seal between the laminate sheets is formed, and the heat-fusible resin is heat-fused by pressurizing / heating in the state of being in close contact with each other on the heat-fusible resin layer side in the periphery. It is done.

  In the positive electrode sheet and the negative electrode sheet, the length and width of the negative electrode sheet facing the positive electrode sheet are made larger than that of the positive electrode sheet so that lithium moving from the positive electrode to the negative electrode during charging does not precipitate in a metallic state, and further insulated. Therefore, the width of the separator is generally larger than that of the negative electrode sheet. However, when the end face of the positive electrode sheet breaks through the separator and comes into contact with the negative electrode sheet, a short circuit occurs, which may lead to abnormal temperature rise or ignition during charging. In medium-sized and large-sized batteries, the battery capacity is increased by increasing the number of stacked positive and negative electrodes. Therefore, the incidence of defects such as short circuits also increases compared to small batteries used in portable devices and the like.

In order to prevent the short circuit, a method of forming an insulating layer such as polyvinylidene fluoride on the exposed portion of the current collector of the positive electrode by a method such as coating drying (Patent Document 1) or a heat-resistant powder such as alumina There has been proposed a method (Patent Document 2) in which a body is bound with a binder to form an insulating film.
JP 2004-259625 A JP 2004-63343 A

  However, when an insulating layer is formed only with a highly crystalline resin such as polyvinylidene fluoride, the resin molecules shrink and the coating film itself shrinks when the coating liquid is dried. Adhesiveness will decrease. For this reason, an insulating layer becomes easy to peel from a collector.

  In addition, when an insulating coating is formed of hard particles such as alumina, although an effect of suppressing the shrinkage of the coating is recognized, the film becomes brittle, so that the problem of peeling off the insulating coating still remains. This phenomenon is particularly noticeable at the edge of the active material layer.

  This invention is made | formed in view of the said situation, Comprising: By covering the end surface of the at least one peripheral edge part of the active material content layer of a positive electrode sheet and a negative electrode sheet with a highly stable insulating resin film, This prevents a short circuit of the non-aqueous electrolyte secondary battery, and improves yield and safety.

  The present invention relates to a positive electrode sheet including a positive electrode current collector and a positive electrode active material-containing layer formed on the positive electrode current collector, and a negative electrode current collector and a negative electrode active material-containing layer formed on the negative electrode current collector. In a non-aqueous electrolyte secondary battery comprising a negative electrode sheet comprising: a separator disposed between the positive electrode sheet and the negative electrode sheet, at least one of the positive electrode active material-containing layer and the negative electrode active material-containing layer The end face of the peripheral end portion is a resin film having a heat resistant resin having a heat resistant temperature of 150 ° C. or higher as a base, and the above problem is solved by covering the inside with an insulating resin film containing a thermoplastic resin. It is something to try.

  A short circuit occurring at the end surface of the peripheral edge of the active material layer of the positive electrode sheet or the negative electrode sheet can be prevented, and a highly safe nonaqueous electrolyte secondary battery can be obtained. In particular, a more remarkable effect is exhibited in a nonaqueous electrolyte secondary battery housed in an outer case made of a laminate sheet.

  In the present invention, the insulating resin film disposed on either the positive electrode, the negative electrode, or the end face of each active material-containing layer has a heat-resistant resin having a heat-resistant temperature of 150 ° C. or higher as a base, and a thermoplastic resin in the inside. It has a form to include.

  The reason why the heat resistance temperature of the resin serving as the base is set to 150 ° C. or higher is to stably maintain the function as an insulating film even at high temperatures, and at least higher than the temperature at which the separator is shut down (approximately 100 to 140 ° C.). This is to ensure stability. As such a resin, a resin having a melting point of 150 ° C. or higher can be used.

  Further, it is desirable to have excellent insulation properties, excellent strength against pressing and rubbing received when the electrodes are stacked, excellent strength against impact received when the battery is dropped, and excellent stability against nonaqueous electrolytes.

  The heat-resistant resin preferably has a large molecular weight and high crystallinity, such as polyvinylidene fluoride and derivatives thereof such as carboxylic acid modified products and maleic acid modified products, vinylidene fluoride-hexafluoropropylene copolymers, and epoxy resins. Polyamide resins and the like are preferably used.

  The heat-resistant resin that can be used is not limited to the high-melting point resin, and even a resin whose melting point is not clearly defined can be stably present up to a temperature of 150 ° C. or higher. Can be used. For example, it is also possible to use a resin having a softening point of 150 ° C. or higher, such as a polysulfone resin such as polyphenylsulfone and polyethersulfone, or a polyimide resin.

  Here, when an insulating resin film is formed from the heat-resistant resin, the resin is generally dissolved in a soluble solvent and subjected to a process of applying and drying the peripheral edge of the active material-containing layer of the electrode sheet. However, a resin having high crystallinity as described above has a large shrinkage at the time of solvent drying and is not flexible enough to easily cause a problem of peeling from an application target. Therefore, in the present invention, an insulating resin film containing a heat-resistant resin as a base contains a thermoplastic resin to relieve shrinkage during the drying of the solvent, and to impart flexibility to the film. Improve membrane durability.

  As the thermoplastic resin, polyolefin resin such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polymethyl methacrylate, ethylene-methyl methacrylate copolymer and derivatives thereof are preferably used. For the purpose of improving the solvent resistance, it is possible to use one obtained by crosslinking a part of the resin.

  The thermoplastic resin is desirably dispersed as uniformly as possible in the insulating resin film. For example, each thermoplastic resin particle may have a sea-island structure in which the periphery of each thermoplastic resin particle is covered with a heat-resistant resin. desirable. This is because it becomes easy to obtain the shrinkage-suppressing effect and the flexibility-imparting effect of the thermoplastic resin while maintaining the film formability and strength of the heat-resistant resin.

  As the thermoplastic resin, one having a particle size smaller than the thickness of the insulating resin film is preferably used. Specifically, the number average particle size is preferably 0.1 to 50 μm, preferably 30 μm or less. Are more preferably used. Moreover, the shape is not limited, and various shapes can be used. From the viewpoint of uniform dispersion, substantially spherical particles are preferably used.

  The ratio of the thermoplastic resin contained in the insulating resin film is preferably 1 wt% or more because the shrinkage-suppressing effect and the flexibility-imparting effect are easily obtained, and more preferably 5 wt% or more. On the other hand, in order to improve the strength of the insulating resin film, it is preferably 80 wt% or less, and more preferably 50 wt% or less.

  Considering the increase in the volume in the exterior body required when the insulating resin film is formed on the end surface of the peripheral end portion of the active material-containing layer of the electrode, the thinner the insulating resin film is, Although it is desirable, if it becomes too thin, the strength becomes insufficient and the function as an insulating layer is impaired. Therefore, it is preferably 5 μm or more, more preferably 10 μm or more, and on the other hand, it is preferably 30 μm or less, and 20 μm. The following is more preferable.

  In the present invention, the insulating resin film can be formed, for example, by the following method. The heat resistant resin is dissolved in a solvent that dissolves the heat resistant resin and does not dissolve the thermoplastic resin, and the thermoplastic resin is further dispersed to prepare a slurry. An insulating resin film can be formed by adhering this slurry to the end face of at least one peripheral end of the positive electrode active material-containing layer and the negative electrode active material-containing layer and further drying the slurry.

  In the present invention, the insulating resin film only needs to cover the end surface of at least one of the active material-containing layer of the positive electrode sheet and the negative electrode sheet, but covers the upper surface of the active material-containing layer or a part of the current collector. By forming the insulating resin film as described above, the adhesiveness of the insulating resin film is improved and the durability is increased, which is preferable.

  In addition, what is necessary is just to form an insulating resin film so that it may not cover the position facing a positive electrode active material content layer, when covering the end surface of a negative electrode active material content layer. In addition, when covering the end face of the positive electrode active material-containing layer, if an insulating resin film is formed also on the upper surface of the active material-containing layer, it will face the negative electrode active material-containing layer, and that portion will be used for charging and discharging. Therefore, it is desirable that the coating width on the upper surface of the active material-containing layer is narrow, for example, 2 mm or less.

  The solvent used for forming the slurry is not particularly limited. For example, when polyvinylidene fluoride is used as the heat-resistant resin and polyethylene is used as the thermoplastic resin, N-methylpyrrolidone or the like is used. A highly versatile solvent can be suitably used. An insulating resin film is formed by applying the slurry to the end of the active material-containing layer of the electrode, or by immersing the peripheral portion of the active material-containing layer of the electrode in the slurry for several seconds to allow the slurry to adhere and drying. Can be formed.

  In order to improve the adhesion between the insulating resin film and the active material-containing layer, the insulating resin film may be heated to a temperature at which the thermoplastic resin is deformed or melted by heating. Note that when the above heating is performed, in order to obtain an effect of improving adhesiveness at a lower temperature, it is desirable that the thermoplastic resin used for the insulating resin film is a resin having a lower melting point than the heat-resistant resin serving as the base.

  In the present invention, as the melting point of the heat-resistant resin or thermoplastic resin, a melting temperature measured using a differential scanning calorimeter (DSC) can be used in accordance with the provisions of JIS K-7121.

Next, other elements constituting the nonaqueous electrolyte secondary battery of the present invention will be described. As the positive electrode active material, for example, Li _{1 + x} MO ₂ (−0.1 ≦ x ≦ 0.1, where M is a transition metal element such as Co, Ni, Mn, Zr, Ti, Al, or the like) is used. Lithium manganese oxide, olivine-type LiMPO ₄ (M: Co), such as lithium-containing transition metal oxide, LiMn ₂ O ₄ , and a part of Li or Mn substituted with other elements (Mg, Ni, Co, Al, etc.) Ni, Mn, Fe, etc.) can be applied. Examples of the lithium-containing transition metal oxide include Li _{(1 + a)} Ni _(1-xy) Mn _x Co _y O ₂ (−0.1 ≦ a ≦ 0.1, 0 ≦ x ≦ 0.5, 0 ≦ y ≦ 0.5), layered oxides such as LiMn _1/3 Ni _1/3 Co _1/3 O ₂ , LiNi _0.77 Co _0.2 Al _0.03 O ₂ can be specifically exemplified. .

  The positive electrode active material constitutes a positive electrode active material-containing layer together with a known conductive additive (carbon material such as carbon black and graphite) and a binder such as polyvinylidene fluoride (PVDF) which are appropriately added as necessary. And it arrange | positions on electrical power collectors, such as aluminum foil, and a positive electrode is formed.

  As the current collector of the positive electrode, a plate-like material such as punching metal can be used in addition to a metal foil such as aluminum, but usually an aluminum foil having a thickness of 10 to 30 μm is preferably used.

  Moreover, as negative electrode active materials, for example, lithium such as graphite, pyrolytic carbons, cokes, glassy carbons, organic polymer compound fired bodies, mesocarbon microbeads (MCMB), carbon fibers can be occluded and released. One kind or a mixture of two or more kinds of carbon-based materials is used. Further, an element such as Si, Sn, Ge, Bi, Sb, In or an alloy thereof or an oxide thereof, a lithium-containing nitride, or a lithium metal or a lithium-aluminum alloy can also be used as the negative electrode active material. In addition to using a negative electrode active material-containing layer formed by appropriately adding a conductive additive (carbon material such as carbon black) or a binder such as PVDF to these negative electrode active materials, You may use what formed the thin film of said various materials on the electrical power collector by plating.

  As the current collector for the negative electrode, a foil made of copper or nickel, a punching metal, a net, an expanded metal, or the like can be used, but usually a copper foil having a thickness of 5 to 30 μm is preferably used.

Nonaqueous electrolytes include, for example, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propionate, ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone, ethylene glycol sulfite, 1,2-dimethoxyethane, 1,3- dioxolane, tetrahydrofuran, 2-methyl - tetrahydrofuran, at least one organic solvent selected from diethyl ether, for _{example, LiClO 4, LiPF 6, LiBF} 4, LiAsF 6, LiSbF 6, LiCF 3 SO 3, LiCF 3 CO 2 _{, Li 2 C 2 F 4 (} SO 3) 2, LiN (CF 3 SO 2) 2, LiC (CF 3 SO 2) 3, LiC n F 2n + 1 SO 3 (n ≧ 2), LiN (RfOS _{2) 2} [where, Rf is a fluoroalkyl group] electrolyte solution and which is prepared by dissolving at least one selected from lithium salts such as, gelled electrolyte is preferably used by which the gelling agent. The concentration of the lithium salt in the electrolytic solution is preferably 0.5 to 1.5 mol / l, and more preferably 0.9 to 1.25 mol / l.

  Hereinafter, the present invention will be described in detail based on examples. However, the following examples do not limit the present invention and can be appropriately changed without departing from the gist of the present invention.

Example 1
<Preparation of positive electrode>
LiCoO _{2 as a} positive electrode active material: 80 parts by mass, acetylene black as a conductive additive: 10 parts by mass, PVDF as a binder: 5 parts by mass, N-methyl-2-pyrrolidone (NMP) as a solvent Was mixed to prepare a positive electrode mixture-containing paste. This paste was applied to both surfaces of a 15 μm-thick aluminum foil serving as a positive electrode current collector, dried at 100 ° C., and then subjected to calendering to form a positive electrode sheet having a width of 60 mm and a total thickness of 120 μm. . Note that the positive electrode active material-containing layer was formed with a width of 60 mm and a length of 115 mm, and a positive electrode current collector portion to which no paste was applied was provided at an end portion in the longitudinal direction of the positive electrode current collector.

<Formation of insulating resin film>
N-methylpyrrolidone (NMP) solution of polyvinylidene fluoride (PVDF), which is a heat-resistant resin (solid content concentration: 12 wt%): 100 g, and polyethylene (PE) powder, which is a thermoplastic resin (average particle diameter: 6 μm): 1.3 g was placed in a container and stirred with a disper at 2800 rpm for 1 hour to obtain a liquid composition. The solution pumped through the tube of thickness 0.5mm and at a discharge rate of 0.1 cm 3 ^/ sec from the syringe, formation of the insulating resin film by coating the end face of the active material-containing layer of the positive electrode sheet and dried I let you. At this time, the insulating resin film was formed on the end face and the top face of the positive electrode active material-containing layer, the thickness of the film on the end face was about 10 μm, and the coating width on the top face was about 0.5 mm. An electron micrograph (SEM image) of the insulating resin film having the above composition is shown in FIG. 1, and the thermoplastic resin 2 is formed so that the heat-resistant resin 1 is a base and the surface is covered with the heat-resistant resin 1. It is recognized that the structure is dispersed inside the insulating resin film.

<Production of negative electrode>
A negative electrode mixture-containing paste was prepared by mixing 90 parts by mass of mesocarbon microbeads as a negative electrode active material and 5 parts by mass of PVDF as a binder so as to be uniform using NMP as a solvent. This negative electrode mixture-containing paste is applied to both sides of a 10 μm-thick negative electrode current collector made of copper foil, dried, and then calendered to form a negative electrode sheet having a width of 64 mm and a total thickness of 115 μm. did. The negative electrode active material-containing layer was formed to have a width of 64 mm and a length of 118 mm, and a negative electrode current collector portion to which no paste was applied was provided at the end in the longitudinal direction of the negative electrode current collector.

  Two separators made of a polyethylene microporous film having a thickness of 30 μm were stacked, and one side thereof was thermally welded to form a bag. The prepared positive electrode sheet is accommodated inside the bag-shaped separator, and 15 negative electrode sheets and 14 positive electrode sheets accommodated in the bag-shaped separator are alternately laminated so that the negative electrode sheets are located on both sides. A laminated body was obtained. The principal part enlarged view of the cross section of the width direction of a laminated body at this time was shown in FIG. That is, FIG. 2 shows a positive electrode sheet 5 comprising a positive electrode current collector 3 and a positive electrode active material-containing layer 4 formed thereon, a negative electrode current collector 6 and a negative electrode active material-containing layer 7 formed thereon. The negative electrode sheet 8 and the separator 11 composed of the above and the insulating resin film 10 conceptually represent the state in which the end surface 4c and the upper surface 4d of the peripheral end portion 4a of the positive electrode active material-containing layer 4 are covered. The coating width of the insulating resin film 10 on the upper surface 4d of the positive electrode active material-containing layer 4 is represented by 4b.

Next, the positive electrode sheet and the negative electrode sheet are coated with a modified polyethylene film on the current collector, and the positive electrode lead terminal is made of aluminum having a thickness of 0.2 mm and a size of 15 mm × 30 mm, and a thickness of 0.2 mm. Were bonded to each other by ultrasonic welding, and the welded portions were protected with polyimide tape. Furthermore, a laminated body of electrodes with lead terminals has a thickness of 60 μm and a size of 80 mm × 290 mm (however, from the center in the longitudinal direction, the electrode has a size of 70 mm × 106 mm and a depth of 4.5 mm. The laminate sheet is housed in the above-mentioned trench, and the sheet is folded in half at the center and overlapped, and one side from which the lead terminal of the electrode protrudes is folded back. Two sides excluding the one side were thermally welded at 150 ° C. for 10 seconds while being pressed with a force of 1 kgf / cm ² and joined.

Before injecting the electrolyte into the exterior of the laminate sheet, a short circuit test was performed by applying an applied voltage of 200 V between the positive electrode and the negative electrode lead terminal, and then an electrolyte having the following composition was applied from the opening of the exterior body. The solution was injected, and the opening was thermally welded and bonded under a reduced pressure of 550 Torr to produce a non-aqueous electrolyte secondary battery having a thickness of 5 mm. The electrolytic solution used at this time was obtained by dissolving LiPF ₆ at a concentration of 1 mol / l in a solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 2, and 2 wt% of cyclohexylbenzene with respect to the mixed solvent. It was prepared by adding%.

The battery is allowed to stand at room temperature for 24 hours, charged to 4.2 V at a constant current of 200 mA, and further subjected to constant current and constant voltage charging for applying a constant voltage of 4.2 V for a total of 7 hours, followed by a constant current of 200 mA. Discharge to 3.0 V (standard charge / discharge). This standard charge / discharge was performed for 3 cycles. The discharge capacity (standard capacity) of the battery at the third cycle was 4 Ah. Next, the battery was charged to 4.2 V under the above conditions, and then stored at 60 ° C. for 30 days. After storage, the battery was allowed to stand at room temperature for 6 hours, standard charge / discharge was performed for 2 cycles, and the discharge capacity (capacity after storage) at the second cycle was measured. From the standard capacity and the capacity after storage, the capacity recovery rate at high temperature storage was calculated by the following formula.
Capacity recovery rate (%) = (Capacity after storage) / (Standard capacity) x 100

(Example 2)
In the formation of the insulating resin film, a positive electrode sheet was prepared in the same manner as in Example 1 except that the amount of polyethylene powder was changed to 3 g, and a nonaqueous electrolyte secondary battery was assembled.

(Example 3)
A positive electrode sheet was prepared in the same manner as in Example 1 except that the amount of polyethylene powder was changed to 5.14 g in forming the insulating resin film, and a nonaqueous electrolyte secondary battery was assembled.

Example 4
In the formation of the insulating resin film, a positive electrode sheet was obtained in the same manner as in Example 1, except that an NMP solution of polyphenylsulfone resin (PPS) (solid content concentration: 12 wt%) was used instead of the NMP solution of polyvinylidene fluoride. And a non-aqueous electrolyte secondary battery was assembled.

(Example 5)
In the formation of the insulating resin film, a positive electrode sheet was prepared in the same manner as in Example 1 except that polypropylene (PP) powder (average particle size: 6 μm): 1.3 g was used instead of polyethylene powder. An electrolyte secondary battery was assembled.

(Example 6)
In forming the insulating resin film, a positive electrode sheet was prepared in the same manner as in Example 1 except that 1.3 g of a crosslinked polymethyl methacrylate resin (PMMA) powder was used instead of polyethylene powder, and a non-aqueous electrolyte secondary was prepared. I assembled the battery.

(Example 7)
A nonaqueous electrolyte secondary battery was assembled in the same manner as in Example 1 except that the insulating resin film was formed on the negative electrode side instead of the positive electrode side. The insulating resin film is formed on the end face and the top face of the negative electrode active material-containing layer, the thickness of the film on the end face is about 10 μm, the covering width on the top face is about 0.5 mm, The insulating resin film formed on the upper surface of the active material-containing layer formed a laminate so as to be disposed at a position not facing the positive electrode active material-containing layer.

  The principal part enlarged view of the cross section of the width direction of a laminated body at this time was shown in FIG. That is, FIG. 3 shows a positive electrode sheet 5 comprising a positive electrode current collector 3 and a positive electrode active material-containing layer 4 formed thereon, a negative electrode current collector 6 and a negative electrode active material-containing layer 7 formed thereon. The negative electrode sheet 8 and the separator 11 composed of the above and the insulating resin film 10 conceptually represent the state in which the end surface 7c and the upper surface 7d of the peripheral end portion 7a of the negative electrode active material-containing layer 7 are covered. It is. The covering width of the insulating resin film 10 on the upper surface 7d of the negative electrode active material-containing layer 7 is represented by 7b.

(Comparative Example 1)
A nonaqueous electrolyte secondary battery was assembled in the same manner as in Example 1 except that the insulating resin film was not formed.

  About 50 each of the nonaqueous electrolyte secondary batteries of Examples 1 to 7 and Comparative Example 1, the number of batteries whose short circuit was confirmed in the short circuit test before injection and the capacity recovery rate (average) in high temperature storage The results are shown in Table 1.

  As can be seen from the results in Table 1, in the nonaqueous electrolyte secondary batteries of Examples 1 to 7 of the present invention, the end surface of at least one of the peripheral end portions of the positive electrode active material-containing layer and the negative electrode active material-containing layer was 150 ° C. A resin film based on a heat-resistant resin having a heat-resistant temperature as described above, which is covered with an insulating resin film containing a thermoplastic resin therein, so that no short circuit occurs and the recovery rate after a storage test is about As a result, the storage characteristics were excellent as compared with the battery of Comparative Example 1 in which the coating treatment was not performed. As described above, according to the present invention, a battery having a high yield and excellent storability can be formed.

  The present invention can be widely used in nonaqueous electrolyte secondary batteries.

The example of the insulating resin film used by this invention shows the electron micrograph of the surface. It is principal part sectional drawing of the electrode laminated body in Example 1 of this invention. It is principal part sectional drawing of the electrode laminated body in Example 7 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat resistant resin 2 Thermoplastic resin 3 Positive electrode collector 4 Positive electrode active material containing layer 4a Circumferential edge part 4b Covering width of insulating resin film 4c End surface 4d Upper surface 5 Positive electrode sheet 6 Negative electrode current collector 7 Negative electrode active material containing layer 7a Peripheral end 7b Covering width of insulating resin film 7c End surface 7d Upper surface 8 Negative electrode sheet 10 Insulating resin film 11 Separator

Claims (11)

A positive electrode sheet including a positive electrode current collector and a positive electrode active material-containing layer formed on the positive electrode current collector, and a negative electrode sheet including a negative electrode current collector and a negative electrode active material-containing layer formed on the negative electrode current collector And a non-aqueous electrolyte secondary battery comprising a separator disposed between the positive electrode sheet and the negative electrode sheet,
An end face of at least one peripheral end of the positive electrode active material-containing layer and the negative electrode active material-containing layer is a resin film based on a heat-resistant resin having a heat-resistant temperature of 150 ° C. or higher, and has a thermoplastic film inside A non-aqueous electrolyte secondary battery, which is covered with an insulating resin film containing a resin. 2. The nonaqueous electrolyte secondary battery according to claim 1, wherein the positive electrode sheet, the negative electrode sheet and the separator are accommodated in an outer case made of a laminate sheet and sealed. The nonaqueous electrolyte secondary battery according to claim 1, wherein the heat resistant resin is a resin having a melting point of 150 ° C. or higher. The nonaqueous electrolyte secondary battery according to claim 3, wherein the heat resistant resin is at least one selected from polyvinylidene fluoride and derivatives thereof. 5. The nonaqueous electrolyte secondary battery according to claim 3, wherein a melting point of the thermoplastic resin is lower than a melting point of the heat resistant resin. The said thermoplastic resin is at least 1 sort (s) chosen from polyolefin, ethylene-vinyl acetate copolymer, polymethylmethacrylate, ethylene-methylmethacrylate copolymer, and its derivative (s), The non in any one of Claims 1-5 Water electrolyte secondary battery. The non-aqueous electrolyte secondary battery according to claim 1, wherein the thermoplastic resin is made of substantially spherical particles. The nonaqueous electrolyte secondary battery according to claim 1, wherein a ratio of the thermoplastic resin contained in the insulating resin film is in a range of 1 to 80 wt%. The nonaqueous electrolyte secondary battery according to claim 1, wherein the insulating resin film has a thickness of 5 to 30 μm. The non-conductive film according to any one of claims 1 to 9, wherein the insulating resin film further covers an upper surface together with an end surface of the peripheral end portion of the positive electrode active material-containing layer, and a covering width on the upper surface is 2 mm or less. Water electrolyte secondary battery. The insulating resin film further covers the upper surface as well as the end surface of the peripheral end of the negative electrode active material-containing layer, and the insulating resin film formed on the upper surface of the negative electrode active material-containing layer is a positive electrode active material-containing layer The nonaqueous electrolyte secondary battery according to claim 1, wherein the nonaqueous electrolyte secondary battery is not opposed to the nonaqueous electrolyte secondary battery.

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