JP4735556B2 - Method for producing solid electrolyte battery - Google Patents

Description

  The present invention relates to a method for manufacturing a solid electrolyte battery, and more particularly to a method for manufacturing a solid electrolyte battery in which a positive electrode and a negative electrode are stacked and wound via a solid electrolyte.

  In recent years, many portable electronic devices such as camera-integrated tape recorders, mobile phones, and portable computers have appeared, and their size and weight have been reduced. And the battery used as the portable power source of these electronic devices is also required to be small and light, and a lithium ion battery has been developed and industrialized as a battery corresponding to this. In this lithium ion battery, a porous polymer separator impregnated with an electrolyte solution is used as an ionic conductor between the positive electrode and the negative electrode, and the entire battery element is made of a heavy metal to prevent leakage of the electrolyte. Packaged in a container.

  On the other hand, a solid electrolyte battery using a solid electrolyte as an ionic conductor between the positive electrode and the negative electrode is expected to reduce the size and weight of the battery by simplifying the package because there is no leakage. In particular, polymer solid electrolytes in which lithium is dissolved in a polymer and gel-like solid electrolytes in which an electrolyte is contained in a matrix polymer are attracting attention.

  Such a solid electrolyte battery can be manufactured as follows. FIG. 10 shows an electrode laminate 13 in which the positive electrode 10 and the negative electrode 11 are laminated via the solid electrolyte layer 12.

  First, as the positive electrode 10, a positive electrode mixture containing a positive electrode active material, a conductive agent, and a binder is uniformly applied to both surfaces of the positive electrode current collector 10a and dried to form the positive electrode active material layer 10b. To do. After drying, it is pressed with a roll press to obtain a positive electrode sheet.

  Next, as the negative electrode 11, the negative electrode active material layer 11b is formed by uniformly applying and drying a negative electrode mixture containing a negative electrode active material and a binder on both surfaces of the negative electrode current collector 11a. After drying, it is pressed with a roll press to obtain a negative electrode sheet.

  In addition, as the solid electrolyte layer 12, a sol-like electrolyte solution containing a nonaqueous solvent, an electrolyte salt, and a matrix polymer is uniformly applied to both surfaces of the positive electrode sheet and the negative electrode sheet and dried to remove the solvent. Thus, the gel-like solid electrolyte layer 12 is formed on the positive electrode active material layer 10b and the negative electrode active material layer 11b.

  And the positive electrode sheet in which the solid electrolyte layer 12 was formed is cut out, for example in a rectangular shape. Further, the solid electrolyte layer 12 and the positive electrode active material layer 10b in the lead welded portion are scraped off, and the lead is welded here to obtain the positive electrode 10 in which the solid electrolyte layer 12 is formed.

  Further, the negative electrode sheet on which the solid electrolyte layer 12 is formed is cut out, for example, in a rectangular shape. Further, the solid electrolyte layer 12 and the negative electrode active material layer 11b at the lead welded portion are scraped off, and the lead is welded to the negative electrolyte 11 in which the solid electrolyte layer 12 is formed.

  Finally, the positive electrode 10 and the negative electrode 11 on which the solid electrolyte layer 12 is formed are laminated to obtain an electrode laminate 13 as shown in FIG. The electrode laminate 13 is sandwiched between exterior films, and the outer peripheral edge of the exterior film is sealed by heat-sealing under reduced pressure, and the electrode winding body is sealed in the exterior film to complete a solid electrolyte battery.

  In the solid electrolyte battery as described above, it is effective to reduce the thickness of the solid electrolyte layer 12 in order to improve the energy density. However, if the thickness of the solid electrolyte layer 12 is reduced, the solid electrolyte layer 12 is easily broken by an external impact, which causes an increase in internal short circuit. For this reason, the thickness of the solid electrolyte layer 12 cannot be reduced, which hinders energy density improvement.

  The cause of the increase in internal short-circuit accompanying the thinning of the solid electrolyte layer 12 is, for example, as shown in FIG. 10, in the conventional solid electrolyte battery, the ends of the positive electrode 10 and the negative electrode 11 are exposed at the end of the electrode laminate 13. Was. Therefore, when the electrode laminate 13 is sealed in the exterior film, an external pressure is applied to the electrode laminate 13, so that the end of the negative electrode 11 is bent at the end of the electrode laminate 13 and short-circuited with the positive electrode 10. Etc. In such a short circuit, as the solid electrolyte layer 12 becomes thinner, the distance between the positive electrode 10 and the negative electrode 11 becomes smaller, so the probability of the short increases.

  Another problem caused by thinning the solid electrolyte layer 12 is powder falling from the electrode surface. When the electrodes are stacked, the active material powder or current collector metal of the electrode falls as a powder and is sandwiched. At this time, when the solid electrolyte layer 12 is thin, micropores are formed in the solid electrolyte layer 12 and an internal short circuit occurs. This powder fallout appears remarkably in the positive electrode 10.

  The present invention has been proposed in view of the above-described conventional situation, and an object of the present invention is to provide a method for manufacturing a high-energy density solid electrolyte battery that prevents an internal short circuit.

In order to solve the above-described problems, the present invention provides a negative electrode forming step in which a negative electrode active material is applied on both sides of a negative electrode current collector and dried to form a strip-shaped negative electrode;
Forming a positive electrode active material on both sides of the positive electrode current collector and drying to form a strip-shaped positive electrode smaller than the negative electrode; and
Applying a sol-like electrolyte solution on the negative electrode and cooling to form a gel-like solid electrolyte layer containing a swelling solvent, forming a negative electrode-side solid electrolyte layer,
A positive electrode that forms a gel-like solid electrolyte layer containing a swelling solvent that has the same width as the negative electrode-side solid electrolyte layer by applying a sol-like electrolyte solution on the positive electrode so as to cover the smaller positive electrode than the negative electrode Forming a side solid electrolyte layer; and
In a state where the negative electrode side solid electrolyte layer and the positive electrode side solid electrolyte layer are laminated facing each other, a winding step of winding the negative electrode and the positive electrode in the longitudinal direction to form an electrode laminate,
The electrode laminate is sandwiched between outer packaging films made of an insulating material, and a thermal fusion process is performed by sealing the periphery of the outer packaging film by thermal fusion under reduced pressure.
This is a method for producing a solid electrolyte battery in which a solid electrolyte layer formed from a negative electrode side solid electrolyte layer and a positive electrode side solid electrolyte layer is larger than the positive electrode and is formed so as to cover the positive electrode .

  In the solid electrolyte battery according to the present invention, the positive electrode is smaller than the negative electrode, and the solid electrolyte layer formed on the small positive electrode is formed to be larger than the small positive electrode. Therefore, the edge part of the positive electrode made small is covered with the solid electrolyte layer, and contact between the positive electrode and the negative electrode at the edge part of the electrode is prevented.

  According to this invention, in the solid electrolyte battery, the positive electrode is made smaller than the negative electrode, and the solid electrolyte layer formed on the positive electrode is formed to be larger than the small positive electrode. Contact between the positive electrode and the negative electrode is prevented at the end portion of the, and the internal short circuit can be greatly reduced.

  Therefore, in this invention, even if the thickness of the solid electrolyte layer is reduced, an internal short circuit can be prevented, and an excellent solid electrolyte battery having a high energy density can be realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings of the following embodiments, the same or corresponding parts are denoted by the same reference numerals.

  One structural example of the gel electrolyte battery which concerns on one Embodiment of this invention is shown in FIGS. In the gel electrolyte battery 1, the electrode laminate 5 shown in FIGS. 2 and 3 is covered and sealed with an exterior film 6 made of an insulating material. As shown in FIGS. 2 and 3, the electrode laminate 5 includes a positive electrode 2, a negative electrode 3 disposed to face the positive electrode 2, and a gel electrolyte layer 4 disposed between the positive electrode 2 and the negative electrode 3. With. The electrode laminate 5 is formed by laminating a positive electrode 2 and a negative electrode 3 with a gel electrolyte layer 4 interposed therebetween. A positive electrode terminal 7 is connected to the positive electrode 2, and a negative electrode terminal 8 is connected to the negative electrode 3, and these positive electrode terminal 7 and negative electrode terminal 8 are at the periphery of the outer film 6 as shown in FIG. 1. It is sandwiched between certain sealing parts.

  As shown in FIG. 4, in the positive electrode 2, positive electrode active material layers 2a containing a positive electrode active material are formed on both surfaces of the positive electrode current collector 2b. For example, a metal foil such as an aluminum foil is used as the positive electrode current collector 2b.

  The positive electrode active material includes lithium cobaltate, lithium nickelate, lithium manganate, those obtained by replacing some of these composite oxides with other transition metals, transition metal compounds such as manganese dioxide and vanadium pentoxide, sulfides, etc. Transition metal chalcogen compounds such as iron can be used.

  Further, in the negative electrode 3, as shown in FIG. 5, a negative electrode active material layer 3a containing a negative electrode active material is formed on both surfaces of the negative electrode current collector 3b. For example, a metal foil such as a copper foil is used as the negative electrode current collector 3b.

  As the negative electrode active material, a material that can be doped or dedoped with lithium can be used. Materials that can be doped and dedoped with lithium include carbon blacks such as pyrolytic carbons, cokes or acetylene black, graphite, glassy carbon, activated carbon, carbon fiber, organic polymer fired body, coffee beans fired Examples thereof include carbon materials such as body, cellulose fired body, and bamboo fired body, and conductive polymers such as lithium metal, lithium alloy, and polyacetylene.

  The gel electrolyte layer 4 contains an electrolyte salt, a matrix polymer, and a swelling solvent as a plasticizer.

As the electrolyte salt, LiPF ₆ , LiAsF ₆ , LiBF ₄ , LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , or the like can be used alone or in combination.

  The matrix polymer is not particularly limited in chemical structure as long as it exhibits an ionic conductivity of 1 mS / cm or more at room temperature. Examples of the matrix polymer include polyacrylonitrile, polyvinylidene fluoride, polytetrafluoroethylene, polyhexafluoropropylene, polyethylene oxide, polypropylene oxide, polyphosphazene, polysiloxane, polyvinyl acetate, polyvinyl alcohol, polymethyl methacrylate, poly Examples include acrylic acid, polymethacrylic acid, styrene-butadiene rubber, nitrile-butadiene rubber, polystyrene, and polycarbonate.

  Examples of the swelling solvent include ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone, γ-valerolactone, diethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxane, methyl acetate, methyl propionate, dimethyl carbonate, Nonaqueous solvents such as diethyl carbonate and ethyl methyl carbonate can be used alone or in combination.

  Here, in the gel electrolyte battery 1 according to one embodiment of the present invention, the positive electrode 2 is made smaller than the negative electrode 3 as shown in FIGS. 4 and 5. As shown in FIG. 6, a gel electrolyte layer 4 is formed on the positive electrode active material layer 2 a of the positive electrode 2 so as to be larger than the positive electrode 2 and cover the positive electrode 2. The positive electrode 2 covered with the gel electrolyte layer 4 has almost the same size as the negative electrode 3. On the other hand, as shown in FIG. 7, the gel electrolyte layer 4 is formed on the negative electrode active material layer 3 a of the negative electrode 3.

  And the positive electrode 2 and the negative electrode 3 in which the gel electrolyte layer 4 was formed are laminated | stacked via the gel electrolyte layer 4, and it is set as the electrode laminated body 5 as shown in FIG.2 and FIG.3. At this time, as described above, since the positive electrode 2 is covered with the gel electrolyte layer 4, when the positive electrode 2 and the negative electrode 3 are used as the electrode laminate 5, the positive electrode 2 is disposed at the end of the electrode laminate 5. Not exposed.

  Therefore, in this gel electrolyte battery 1, for example, when the electrode laminate 5 is sealed in the exterior film 6, even if an external pressure is applied to the electrode laminate 5 and the end portion of the negative electrode 3 is bent, the end portion of the positive electrode 2. Is covered with the gel electrolyte, the internal short circuit can be greatly reduced without contact between the negative electrode 3 and the positive electrode 2.

  Furthermore, in this gel electrolyte battery 1, as described above, since the internal short circuit can be reduced by covering the end portion of the positive electrode 2 with the gel electrolyte, the gel electrolyte layer 4 between the positive electrode 2 and the negative electrode 3 can be reduced. It becomes possible to reduce the thickness. Therefore, in this gel electrolyte battery 1, the proportion of the positive electrode active material layer 2a and the negative electrode active material layer 3a increases as the thickness of the gel electrolyte layer 4 decreases, and the energy density can be improved.

  In this gel electrolyte battery 1, as shown in FIG. 8, the gel electrolyte layer 4 formed on the negative electrode active material layer 3 a may be formed so as to be larger than the negative electrode 3 and cover the negative electrode 3. . By covering not only the positive electrode 2 but also the end of the negative electrode 3 with the gel electrolyte, contact between the negative electrode 3 and the positive electrode 2 can be more completely prevented, and internal shorts can be more effectively reduced. . Furthermore, by forming the gel electrolyte layer 4 larger than the negative electrode 3, it is possible to prevent the electrode active material and the current collector metal from falling off. Thereby, the electrode active material and the current collector metal powder are not sandwiched when the electrodes are laminated, and an internal short circuit due to the rupture of the gel electrolyte layer 4 can be eliminated.

  Next, a method for producing such a gel electrolyte battery 1 will be described.

  First, as the positive electrode 2, a positive electrode active material containing a positive electrode active material and a binder is uniformly coated on a metal foil such as an aluminum foil, for example, an aluminum foil to be the positive electrode current collector 2b, and then dried. The layer 2a is formed to produce a positive electrode sheet. As the binder of the positive electrode mixture, a known binder can be used, and a known additive or the like can be added to the positive electrode mixture.

  Next, the positive electrode sheet is cut into a rectangular shape. Then, the portion of the positive electrode active material layer 2a to which the lead is welded is scraped, and an aluminum lead, for example, is welded to form the positive electrode terminal 7. In this way, the positive electrode 2 is obtained.

  Next, the gel electrolyte layer 4 is formed on the positive electrode active material layer 2 a of the positive electrode 2. In order to form the gel electrolyte layer 4, first, an electrolyte salt is dissolved in a non-aqueous solvent to prepare a non-aqueous electrolyte. Then, a matrix polymer is added to this non-aqueous electrolyte, and the mixture is well stirred to dissolve the matrix polymer to obtain a sol electrolyte solution.

  Next, this electrolyte solution is uniformly applied on the positive electrode 2 placed on a flat glass plate. At this time, the electrolyte solution is applied not only on the positive electrode active material layer 2a but also on a portion protruding from the positive electrode active material layer 2a. Subsequently, the matrix polymer is gelled by cooling at room temperature, and the gel electrolyte layer 4 is formed on the positive electrode active material layer 2a. Next, the positive electrode 2 is returned, and the electrolyte solution is similarly applied onto the other positive electrode active material layer 2a and dried. In this way, the gel electrolyte layer 4 is formed on both surfaces of the positive electrode 2.

  Next, the gel electrolyte layer 4 is cut out so that the gel electrolyte layer 4 protrudes outward from each end of the positive electrode 2 by a predetermined width, for example, 1 mm. In this way, the positive electrode 2 is obtained in which both surfaces from the end of the positive electrode active material layer 2a to the portion having a predetermined width are covered with the gel electrolyte layer 4.

  In addition, the negative electrode 3 is formed by uniformly applying a negative electrode mixture containing a negative electrode active material and a binder onto a metal foil such as a copper foil to be the negative electrode current collector 3b and drying the negative electrode active material layer. 3a is formed and a negative electrode sheet is produced. As the binder of the negative electrode mixture, a known binder can be used, and a known additive or the like can be added to the negative electrode mixture.

Next, the gel electrolyte layer 4 is formed on the negative electrode active material layer 3a of the negative electrode sheet. In order to form the gel electrolyte layer 4, first, an electrolyte solution prepared in the same manner as described above is applied on the negative electrode active material layer 3a in a predetermined amount. Subsequently, the matrix polymer is gelled by cooling at room temperature, and the gel electrolyte layer 4 is formed on the negative electrode active material layer 3a.

  Next, the negative electrode sheet on which the gel electrolyte layer 4 is formed is cut into a rectangular shape. Then, the gel electrolyte layer 4 and the negative electrode active material layer 3a at the portion where the lead is welded are scraped off, and a nickel lead, for example, is welded to form the negative electrode terminal 8. In this way, the negative electrode 3 on which the gel electrolyte layer 4 is formed is obtained.

  Then, the positive electrode 2 and the negative electrode 3 produced as described above are pressed with the side on which the gel electrolyte layer 4 is formed facing each other, and pressed to obtain an electrode laminate 5.

  Finally, the electrode laminate 5 is packed with an exterior film 6 made of an insulating material, and the positive electrode terminal 7 and the negative electrode terminal 8 are sandwiched between sealing portions, whereby the gel electrolyte battery 1 is completed.

  In the above-described embodiment, the case where the rectangular positive electrode 2 and the rectangular negative electrode 3 are laminated to form the electrode laminate 5 has been described as an example, but the present invention is limited to this. Instead, as shown in FIG. 9, the belt-like positive electrode 2 and the belt-like negative electrode 3 are laminated to form an electrode laminate, and this electrode laminate is wound in the longitudinal direction to obtain an electrode winding body. Applicable.

  Hereinafter, in order to confirm the effect of the present invention, a gel electrolyte battery was prepared and its characteristics were evaluated. In addition, this invention is not limited only to these Examples.

<Example 1>
First, the positive electrode was produced as follows.

In order to produce the positive electrode, first, 0.5 mol of lithium carbonate and 1 mol of cobalt carbonate were mixed and baked in air at 900 ° C. for 5 hours to obtain LiCoO _{2 serving} as a positive electrode active material. . 91 parts by weight of this LiCoO ₂ , 6 parts by weight of graphite as a conductive agent, and 3 parts by weight of polyvinylidene fluoride as a binder were mixed and dispersed in N-methylpyrrolidone to form a slurry. This slurry was uniformly applied to both surfaces of a positive electrode current collector made of an aluminum foil having a thickness of 20 μm and dried to form a positive electrode active material layer. After drying, it was pressed with a roll press to obtain a positive electrode sheet. The density of the positive electrode active material layer at this time was 3.6 g / cm ³ .

  Then, the positive electrode sheet produced as described above was cut out in a shape in which a 5 mm × 5 mm lead weld portion was attached to a 30 mm × 50 mm portion. The positive electrode active material layer in the lead welded portion was scraped off, and an aluminum lead was welded here to form a positive electrode terminal. In this way, a positive electrode was produced.

And the gel electrolyte layer was formed on the positive electrode on the positive electrode produced as mentioned above. In order to form the gel electrolyte layer, first, 42.5 parts by weight of ethylene carbonate, 42.5 parts by weight of propylene carbonate, and 15 parts by weight of LiPF ₆ were mixed to obtain a plasticizer. 30 plasticizers
10 parts by weight of a polymer obtained by copolymerizing vinylidene fluoride and hexafluoropropylene at a polymerization ratio of 97 to 3 as a matrix polymer, and 60 parts by weight of tetrahydrofuran are mixed and dissolved. An electrolyte solution was obtained.

  Next, this electrolyte solution was uniformly applied on the positive electrode placed on a flat glass plate. At this time, the electrolyte solution was applied not only on the positive electrode but also on a portion protruding from the positive electrode. Thereafter, it was dried to remove tetrahydrofuran. Next, this positive electrode was returned, and the electrolyte solution was similarly applied to the other surface of the positive electrode and dried. In this way, a gel electrolyte layer having a thickness of 12.5 μm was formed on both surfaces of the positive electrode.

  Next, the gel electrolyte layer was cut out so that the gel electrolyte layer would protrude 1 mm outward from each end of the positive electrode. In this way, a positive electrode was obtained in which portions within 12.5 μm on both surfaces of the positive electrode from the end of the positive electrode active material layer to the portion protruding 1 mm were covered with the gel electrolyte layer.

  Next, the negative electrode was produced as follows.

To prepare the negative electrode, first, 90 parts by weight of graphite and 10 parts by weight of polyvinylidene fluoride were mixed and dispersed in N-methylpyrrolidone to form a slurry. This slurry was uniformly applied to both surfaces of a negative electrode current collector made of a copper foil having a thickness of 10 μm and dried to form a negative electrode active material layer. After drying, it was pressed with a roll press to obtain a negative electrode sheet. At this time, the density of the negative electrode active material was 1.6 g / cm ³ .

  Next, a gel electrolyte layer was formed on the negative electrode sheet. In order to form the gel electrolyte layer, the electrolyte solution prepared in the same manner as described above was uniformly applied to both sides of the negative electrode sheet and dried to remove tetrahydrofuran. In this way, a gel electrolyte layer having a thickness of 12.5 μm was formed on the negative electrode active material layer.

  And the negative electrode sheet | seat in which the gel electrolyte layer was formed was cut out in the form where the lead welding part of 5 mm x 5 mm is attached to the part of 32 mm x 52 mm. The gel electrolyte layer and the negative electrode active material layer at the lead welded portion were scraped off, and a nickel lead was welded to form a negative electrode terminal. In this way, a negative electrode was produced.

  Next, the positive electrode with the gel electrolyte layer formed on both sides and the negative electrode with the gel electrolyte layer formed on both sides were laminated in the order of negative electrode, positive electrode, negative electrode, positive electrode, and negative electrode. Thus, an electrode laminate was obtained.

  Finally, this electrode laminate is sandwiched by an exterior film in which 25 μm-thick nylon, 40 μm-thick aluminum, and 30 μm-thick polypropylene are laminated in order from the outermost layer, and the outer peripheral edge of the exterior film is melted under reduced pressure. The electrode laminate was sealed in an exterior film. At this time, the positive electrode terminal and the negative electrode terminal were sandwiched between the sealing portions of the exterior film. In this way, a gel electrolyte battery was completed.

<Comparative example 1>
A gel electrolyte battery was produced in the same manner as in Example 1 except that the positive electrode was produced as follows.

  First, a positive electrode sheet and an electrolyte solution were prepared in the same manner as in the example.

  Next, a gel electrolyte layer was formed on the positive electrode sheet. In order to form the gel electrolyte layer, the electrolyte solution was uniformly applied on both sides of the positive electrode sheet, and then dried to remove tetrahydrofuran. In this way, a gel electrolyte layer having a thickness of 12.5 μm was formed on the positive electrode active material layer.

  And the positive electrode sheet | seat in which the gel electrolyte layer was formed was cut out in the form where the lead welding part of 5 mm x 5 mm is attached to the part of 30 mm x 50 mm. The gel electrolyte layer and the positive electrode active material layer at the lead welded portion were scraped off, and an aluminum lead was welded to form a positive electrode terminal. In this way, a positive electrode having a gel electrolyte layer with a thickness of 12.5 μm formed on both surfaces was obtained.

<Comparative example 2>
A gel electrolyte battery was produced in the same manner as in Comparative Example 1 except that the thickness of the gel electrolyte layer formed on the positive electrode and the negative electrode was 50 μm.

<Comparative Example 3>
A gel electrolyte battery was produced in the same manner as in Comparative Example 1 except that the thickness of the gel electrolyte layer formed on the positive electrode and the negative electrode was 100 μm.

  In Example 2 and Comparative Examples 4 to 6 shown below, a battery was fabricated using an electrode winding body in which a belt-like positive electrode and a negative electrode were laminated and wound in the longitudinal direction.

<Example 2>
First, a positive electrode sheet, a negative electrode sheet, and an electrolyte solution were produced in the same manner as in Example 1.

  Next, the obtained positive electrode sheet was cut into a shape in which a 50 mm × 260 mm lead welded portion was attached to a 50 mm × 260 mm portion. The positive electrode active material layer in the lead welded portion was scraped off, and an aluminum lead was welded here to form a positive electrode terminal. In this way, a positive electrode was produced.

  And the gel electrolyte layer was formed on the positive electrode on the positive electrode produced as mentioned above. In order to form the gel electrolyte layer, the electrolyte solution was uniformly applied on the positive electrode placed on a flat glass plate. At this time, the electrolyte solution was applied not only on the positive electrode but also on a portion protruding from the positive electrode. Thereafter, it was dried to remove tetrahydrofuran. Next, this positive electrode was returned, and the electrolyte solution was similarly applied to the other surface of the positive electrode and dried. In this way, a gel electrolyte layer having a thickness of 12.5 μm was formed on both surfaces of the positive electrode.

  Next, the gel electrolyte layer was cut out so that the gel electrolyte layer would protrude 1 mm outward from each end of the positive electrode. In this way, a positive electrode was obtained in which portions within 12.5 μm on both surfaces of the positive electrode from the end of the positive electrode active material layer to the portion protruding 1 mm were covered with the gel electrolyte layer.

  On the other hand, the gel electrolyte layer was formed on the negative electrode sheet in the same manner as in Example 1, and this negative electrode sheet was cut into a shape in which a 52 mm × 5 mm lead weld portion was attached to a 52 mm × 300 mm portion. The gel electrolyte layer and the negative electrode active material layer at the lead welded portion were scraped off, and a nickel lead was welded to form a negative electrode terminal. In this way, a negative electrode was produced.

  Next, a belt-like positive electrode having a gel electrolyte layer formed on both sides and a belt-like negative electrode having a gel electrolyte layer formed on both sides, which are produced as described above, are laminated to form a laminate, and this laminate is further laminated. An electrode winding body was obtained by winding the body in the longitudinal direction.

  Next, the electrode winding body is sandwiched between an outer film in which 25 μm-thick nylon, 40 μm-thick aluminum, and 30 μm-thick polypropylene are laminated in order from the outermost layer, and the outer peripheral edge of the outer film is heated under reduced pressure. Sealing was performed by fusing, and the electrode winding body was sealed in the exterior film. At this time, the positive electrode terminal and the negative electrode terminal were sandwiched between the sealing portions of the exterior film. In this way, a gel electrolyte battery was completed.

<Comparative example 4>
A gel electrolyte battery was produced in the same manner as in Example 2 except that the positive electrode was produced as follows.

  First, a positive electrode sheet and an electrolyte solution were prepared in the same manner as in Example 1.

  Next, a gel electrolyte layer was formed on the positive electrode sheet. In order to form the gel electrolyte layer, the electrolyte solution was uniformly applied on both sides of the positive electrode sheet, and then dried to remove tetrahydrofuran. In this way, a gel electrolyte layer having a thickness of 12.5 μm was formed on the positive electrode active material layer.

  And the positive electrode sheet | seat in which the gel electrolyte layer was formed was cut out in the form where the lead welding part of 50 mm x 5 mm is attached to the part of 50 mm x 260 mm. The gel electrolyte layer and the positive electrode active material layer at the lead welded portion were scraped off, and an aluminum lead was welded to form a positive electrode terminal. In this way, a positive electrode having a gel electrolyte layer with a thickness of 12.5 μm formed on both surfaces was obtained.

<Comparative Example 5>
A gel electrolyte battery was produced in the same manner as in Comparative Example 4 except that the thickness of the gel electrolyte layer formed on the positive electrode and the negative electrode was 50 μm.

<Comparative Example 6>
A gel electrolyte battery was produced in the same manner as in Comparative Example 4 except that the thickness of the gel electrolyte layer formed on the positive electrode and the negative electrode was 100 μm.

  With respect to the gel electrolyte batteries of Examples 1, 2 and Comparative Examples 1 to 6 produced as described above, the internal short-circuit occurrence rate and the energy density were measured. The measurement was performed for 50 batteries. The energy density is a value that does not include the lead and the exterior part, and is an average value of 50 batteries.

  Table 1 shows the internal short-circuit occurrence rate and energy density measured for the gel electrolyte batteries of Example 1, Example 2, and Comparative Examples 1 to 6.

  From Table 1, it can be seen that the battery of Example 1 has a higher energy density and a lower internal short circuit rate than the batteries of Comparative Examples 1 to 3. Further, even in the battery of Example 2 in which the positive electrode and the negative electrode are wound as an electrode, the energy density is higher and the internal short-circuit occurrence rate is suppressed lower than the batteries of Comparative Examples 4 to 6. I understand that.

  Therefore, it was found that by covering the positive electrode with the gel electrolyte, contact between the negative electrode and the positive electrode can be prevented, and the internal short circuit can be greatly reduced. Moreover, since the internal short circuit can be reduced by covering the positive electrode with the gel electrolyte, it becomes possible to reduce the thickness of the gel electrolyte layer between the positive electrode and the negative electrode, and to improve the energy density. It was.

  The embodiment of the present invention has been specifically described above, but the present invention is not limited to the above-described embodiment, and various modifications based on the technical idea of the present invention are possible.

  For example, the numerical values given in the above-described embodiment are merely examples, and different numerical values may be used as necessary.

  In addition, the gel electrolyte battery 1 according to the embodiment as described above is not particularly limited with respect to its shape, such as a cylindrical shape or a rectangular shape, and has various sizes such as a thin shape and a large size. Can do.

  Moreover, in one Embodiment mentioned above, although the gel electrolyte battery 1 containing a swelling solvent and using a gel-like solid electrolyte was mentioned as an example as a solid electrolyte battery, this invention is limited to this. Instead, the present invention can also be applied to a solid electrolyte battery using a solid electrolyte containing no swelling solvent. The present invention can be applied to both a primary battery and a secondary battery.

It is a perspective view which shows one structural example of the nonaqueous electrolyte battery which concerns on one Embodiment of this invention. It is a perspective view which shows one structural example of the electrode laminated body used for the nonaqueous electrolyte battery of FIG. FIG. 3 is a cross-sectional view taken along line XY in FIG. It is a perspective view which shows one structural example of a positive electrode. It is a perspective view which shows one structural example of a negative electrode. It is a perspective view which shows the state in which the solid electrolyte layer was formed on the positive electrode of FIG. FIG. 6 is a perspective view showing a state in which a solid electrolyte layer is formed on the negative electrode in FIG. 5. It is a perspective view which shows another structural example of an electrode laminated body. FIG. 4 is a perspective view showing a configuration example of an electrode winding body in which a positive electrode and a negative electrode are wound, with a part cut away. It is sectional drawing which shows the example of 1 structure of the conventional electrode laminated body.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Gel electrolyte battery, 2 ... Positive electrode, 3 ... Negative electrode, 4 ... Gel electrolyte layer, 5 ... Electrode laminated body, 6 ... Exterior film, 7 ... Positive electrode terminal, 8 ... Negative terminal

Claims (2)

Forming a negative electrode active material on both sides of the negative electrode current collector and drying to form a strip-shaped negative electrode; and
Forming a positive electrode active material on both sides of the positive electrode current collector and drying to form a strip-shaped positive electrode smaller than the negative electrode; and
Applying a sol-like electrolyte solution on the negative electrode and cooling to form a gel-like solid electrolyte layer containing a swelling solvent, forming a negative electrode-side solid electrolyte layer,
A gel-like solid electrolyte layer containing a swelling solvent having the same width as the negative electrode-side solid electrolyte layer is applied by cooling a sol-like electrolyte solution on the positive electrode so as to cover the positive electrode smaller than the negative electrode. Forming a positive electrode side solid electrolyte layer to be formed; and
A winding step of winding the negative electrode and the positive electrode in the longitudinal direction to form an electrode laminate in a state where the negative electrode side solid electrolyte layer and the positive electrode side solid electrolyte layer are laminated facing each other;
The electrode laminate is sandwiched between exterior films made of an insulating material, and a heat sealing step is performed by sealing the periphery of the exterior film by heat-sealing under reduced pressure,
A method for producing a solid electrolyte battery, wherein a solid electrolyte layer formed from the negative electrode side solid electrolyte layer and the positive electrode side solid electrolyte layer is larger than the positive electrode and covers the positive electrode . In the negative electrode forming step, the negative electrode active material is uniformly coated on both sides of the negative electrode current collector made of metal foil and dried to form a negative electrode active material layer, which is then pressed by a roll press to form a strip-shaped negative electrode And
In the positive electrode forming step, the positive electrode active material is uniformly applied on both sides of the positive electrode current collector made of metal foil and dried to form a positive electrode active material layer, and then pressed with a roll press to form a belt-like positive electrode The method for producing a solid electrolyte battery according to claim 1.

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