JP2014211946A - Electrode plate for nonaqueous secondary battery and nonaqueous secondary battery using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous secondary battery securing a liquid-injection passage to a mixture layer 13, improving impregnation properties of a nonaqueous electrolyte into the mixture layer 13 and liquid-retaining properties, and capable of achieving high capacity and improvement in productivity.SOLUTION: There is provided a nonaqueous secondary battery in which a liquid-injection passage to a mixture layer 13 is secured, an impregnation properties of a nonaqueous electrolyte into the mixture layer 13 and liquid-retaining properties are improved, and also battery capacity and productivity can be improved by making the thickness of an end of the mixture layer 13 thinner than that of a part other than the end of the mixture layer 13, and covering a surface of the mixture layer 13 with a surface layer 14 having lower impregnation properties than the mixture layer 13 so that at least a part of the end of the mixture layer 13 is exposed.

Description

  The present invention relates to an electrode plate for a non-aqueous secondary battery represented by a lithium ion battery and a non-aqueous secondary battery using the same.

In recent years, lithium ion secondary batteries, which are increasingly used as power sources for electric vehicles, use a carbonaceous material capable of occluding and releasing lithium in the negative electrode plate, and contain a transition metal such as LiCoO ₂ and lithium in the positive electrode plate The composite oxide is used as the positive electrode active material, and as a result, a secondary battery with a high potential and a high discharge capacity is realized. Life expectancy and high safety are desired.

  Here, as an electrode plate for realizing a high capacity, long life, and high safety battery, an electrode mixture paint made by coating each constituent material on both the positive electrode plate and the negative electrode plate is placed on the current collector. The method of apply | coating is used, Furthermore, the method of apply | coating multiple layers of mixture layers is also proposed.

  At this time, a longer life and higher safety can be achieved depending on the material properties of the surface layer to be applied.

  On the other hand, when the mixture layer is applied to the current collector as described above, the end portion of the mixture layer is swelled by the surface tension of the paste. A method for preventing an internal short circuit has been proposed. (For example, refer to Patent Document 1).

JP 2010-262773 A

  However, in the conventional technique shown in Patent Document 1 described above, the electrolyte injection path formed between the end of the raised mixture layer and the separator is narrowed by the rise of the end of the mixture layer. Therefore, there was a problem of inhibiting the impregnation of the electrolytic solution into the central portion of the mixture layer. In addition, the position of the end portion of the raised mixture layer has to be defined, which has a problem that the productivity of the non-aqueous secondary battery is lowered.

  The present invention solves the above-mentioned conventional problems, and makes the thickness of the end portion of the mixture layer thinner than the thickness other than the end portion of the mixture layer, and at least a part of the end portion of the mixture layer The surface of the mixture layer is covered with a surface layer having a lower impregnation property than the mixture layer so as to expose the mixture layer, and a liquid injection path to the mixture layer is secured. An object of the present invention is to provide a non-aqueous secondary battery that can improve the impregnation property and liquid retention property of a non-aqueous electrolyte and improve battery capacity and productivity.

  In order to achieve the above object, an electrode plate for a non-aqueous secondary battery and a non-aqueous secondary battery using the same according to the present invention are obtained by forming a mixture layer containing an active material on the surface of a current collector. The mixture layer is formed so that the end portion of the mixture layer is thinner than the end portion of the mixture layer and at least a part of the end portion of the mixture layer is exposed. The surface is covered with a surface layer having a lower impregnation property than the mixture layer.

  ADVANTAGE OF THE INVENTION According to this invention, while improving the impregnation property and liquid retention property of the non-aqueous electrolyte to a mixture layer, battery capacity and productivity can be improved.

1 is a partially cutaway perspective view of a nonaqueous secondary battery according to Embodiment 1 of the present invention. Schematic diagram of a cross section of the electrode plate for a non-aqueous secondary battery in Embodiment 1 of the present invention. Schematic diagram of the surface of the electrode plate for a non-aqueous secondary battery in Embodiment 1 of the present invention Schematic diagram of a cross section of the electrode plate for a non-aqueous secondary battery in Embodiment 2 of the present invention. The schematic diagram of the surface of the electrode plate for non-aqueous secondary batteries in other embodiment of this invention Schematic diagram of cross section of electrode plate for non-aqueous secondary battery in comparative example

  1st invention of this invention is the electrode plate for batteries which formed the mixture layer containing an active material on the surface of a collector, The thickness of the edge part of the said mixture layer is other than the edge part of the said mixture layer The surface of the mixture layer was covered with a surface layer having a lower impregnation property than the mixture layer so as to be thinner than the thickness and to expose at least a part of the end portion of the mixture layer. As a result, it is possible to improve the impregnation property and liquid retention property of the nonaqueous electrolytic solution into the mixture layer. In addition, since there is no rise at the end portion of the mixture layer, it is not necessary to define the position of the end portion of the mixture layer, and the productivity of the nonaqueous secondary battery can be improved.

According to a second aspect of the present invention, the thickness of the end portion of the mixture layer is reduced toward the end portion of the mixture layer, thereby impregnating the non-aqueous electrolyte into the mixture layer and retaining the liquid. Battery capacity and productivity can be improved.
According to a third aspect of the present invention, by exposing either one end of the mixture layer in the longitudinal direction of the electrode plate or the both ends, the impregnation property of the non-aqueous electrolyte into the mixture layer While improving liquid retention, battery capacity and productivity can be improved.

  According to a fourth aspect of the present invention, the mixture layer is impregnated with the nonaqueous electrolyte solution by exposing either one of the both end portions of the mixture layer in the electrode plate width direction or the both end portions. While improving liquid retention, battery capacity and productivity can be improved.

  According to a fifth aspect of the present invention, the surface layer is different from the active material of the mixture layer in a nickel-based composite oxide such as a lithium nickel acid composite oxide, a cobalt-based composite oxide such as a lithium cobalt acid composite oxide, cobalt Manganese complex oxides such as acid nanoparticles, cobalt oxynitrides, lithium manganate complex oxides, chromium complex oxides such as lithium chromate complex oxides, iron phosphates such as lithium iron phosphate complex oxides Use one of complex oxides, vanadium-based complex oxides such as vanadium pentoxide, titanium-based complex oxides such as graphite, hard carbon, and lithium-titanium complex oxides, tin oxide glass, silica-based alloy composition materials, and metallic lithium. This improves the reactivity of lithium on the electrode plate surface and improves the impregnation and liquid retention of non-aqueous electrolyte. It is possible to obtain excellent electrode plate of the productivity.

  According to a sixth aspect of the present invention, a positive electrode mixture coating material obtained by kneading and dispersing at least a positive electrode active material comprising a lithium-containing composite oxide, a conductive material, and a binder with a dispersion medium is adhered onto a positive electrode current collector. A porous insulator is interposed between the positive electrode plate on which the positive electrode mixture layer is formed and the negative electrode plate on which a negative electrode active material made of a material capable of holding at least lithium is supported. A non-aqueous secondary battery in which an electrode group formed by winding is enclosed in a battery case together with a non-aqueous electrolyte, and the electrode plate is a non-aqueous secondary battery electrode according to any one of the first to fifth inventions By using the plate, it is possible to improve the impregnation property and liquid retention property of the non-aqueous electrolyte into the mixture layer, and improve the battery capacity and productivity.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.
(Embodiment 1)
FIG. 1 is a partially cutaway perspective view of a cylindrical lithium ion secondary battery 11 as an example of a non-aqueous secondary battery in the present invention.

  A cylindrical lithium ion secondary battery 11 includes a positive electrode plate 1 using a lithium-containing composite oxide as a positive electrode active material and a negative electrode plate 2 using a material capable of holding lithium as a negative electrode active material as a porous insulator 3. The electrode group 4 is produced by spirally winding the separator.

  The electrode group 4 is housed inside a bottomed cylindrical battery case 5 that is an exterior body, insulated from the battery case 5 by an insulating plate 6, while a negative electrode lead 7 led out from the lower part of the electrode group 4 is provided. The positive electrode lead 8 led out from the upper part of the electrode group 4 is connected to the sealing plate 9 while being connected to the bottom of the battery case 5. The spiral electrode group 4 is housed inside a bottomed cylindrical battery case 5, and then a non-aqueous electrolyte composed of a predetermined amount of a non-aqueous solvent is injected into the battery case 5. A sealing plate 9 with a gasket 10 attached to the periphery is inserted into the opening, and the opening of the battery case 5 is folded inward to seal it. At that time, a gap is formed between the electrode group 4 and the battery case 5 and in the central portion of the electrode group 4.

FIG. 2 shows a schematic view of a cross section of the negative electrode plate 2 for a non-aqueous secondary battery in one embodiment of the present invention. FIG. 3 is a schematic view of the surface of the negative electrode plate 2 for a non-aqueous secondary battery in one embodiment of the present invention.
The negative electrode plate 2 is formed by forming a negative electrode mixture layer 13 on the surface of the negative electrode current collector 12. At this time, the thickness of both ends of the negative electrode mixture layer 13 in the longitudinal direction of the negative electrode plate is configured so as to become thinner toward the end of the negative electrode mixture layer 13, and as shown in FIG. The length X that becomes thinner toward the end of the negative electrode mixture layer 13 is configured such that the ratio to the thickness Z of the negative electrode mixture layer 13 is 1 or less. Here, the end portion of the negative electrode mixture layer 13 refers to a portion of 20 mm or less from the position at which the negative electrode mixture layer 13 starts to be applied to the negative electrode current collector 12 or has been applied.

  Then, the surface excluding both ends of the negative electrode mixture layer 13 is covered with a surface layer 14 having a lower impregnation property than the negative electrode mixture layer 13 so that both ends of the negative electrode mixture layer 13 are completely exposed. The application start position Y of the surface layer 14 is configured to be larger than X. That is, a surface layer having a lower impregnation property than the negative electrode mixture layer 13 is applied to the surface of the negative electrode mixture layer 13 excluding the surface of the end portion of the negative electrode mixture layer 13. A part of the surface is exposed. The negative electrode lead 7 is bonded onto the negative electrode current collector 12 in the vicinity of the outer peripheral side end of the negative electrode mixture layer 13.

  As the negative electrode active material, various natural graphites and artificial graphites, silicon-based composite materials such as silicide, and various alloy composition materials can be used.

  Various binders such as PVdF and modified products thereof can be used as the binder for the negative electrode. From the viewpoint of improving lithium ion acceptability, styrene-butadiene copolymer rubber particles (SBR) and modified products thereof are added to carboxy. It can be said that it is more preferable to use a cellulose resin such as methylcellulose (CMC) or the like in combination or to add a small amount.

  Next, the active material of the surface layer 14, the conductive agent, and the binder are put in an appropriate dispersion medium, and mixed and dispersed by a dispersing machine such as a planetary mixer to obtain an optimum viscosity for application to the negative electrode mixture layer 13. Adjustment was performed and kneading was performed to prepare a paint to be applied to the surface layer.

As the active material of the surface layer 14, titanium-based composite oxides such as lithium titanium composite oxide and various alloy composition materials can be used.
On the other hand, as the surface layer binder, PVdF and its various modified binders can be used in the same manner as the negative electrode binder. From the viewpoint of improving lithium ion acceptability, styrene-butadiene copolymer rubber particles ( It can be said that it is more preferable to use a cellulosic resin including carboxymethyl cellulose (CMC) or the like in combination with SBR) or a modified product thereof or to add a small amount thereof.

  As the conductive material at this time, for example, carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, and various graphites such as carbon nanotubes and VGCF may be used alone or in combination.

  The negative electrode mixture paint and the surface layer paint produced as described above were applied on the negative electrode current collector 12 made of copper foil, and the surface layer of the negative electrode mixture layer 13 was further coated with a die coater. 14 is applied and dried, and then compressed to a predetermined thickness by a press, whereby a predetermined negative electrode plate 2 can be obtained. And the negative electrode lead 7 is joined on the collector 12 near the edge part of the said negative mix layer outside the electrode group at the time of carrying out a group structure.

  For the positive electrode plate 1, as the positive electrode active material, for example, lithium cobaltate and modified products thereof (such as lithium cobaltate in which aluminum or magnesium is dissolved), lithium nickelate and modified products thereof (partially nickel is substituted with cobalt) And composite oxides such as lithium manganate and modified products thereof.

  As the conductive material at this time, for example, carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black and thermal black, and various graphites may be used alone or in combination.

  As the positive electrode binder, for example, polyvinylidene fluoride (PVdF), a modified polyvinylidene fluoride, polytetrafluoroethylene (PTFE), a rubber particle binder having an acrylate unit, and the like can be used. In this case, an acrylate monomer or an acrylate oligomer into which a reactive functional group is introduced may be mixed in the binder.

For the non-aqueous electrolyte, various lithium compounds such as LiPF ₆ and LiBF ₄ can be used as the electrolyte salt. Further, ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and methyl ethyl carbonate (MEC) can be used alone or in combination as a solvent. It is also preferable to use vinylene carbonate (VC), cyclohexylbenzene (CHB), and modified products thereof in order to form a good film on the positive and negative electrode plates and to ensure stability during overcharge.
The separator as the porous insulator 3 is not particularly limited as long as it has a composition that can withstand the range of use of the lithium ion secondary battery. However, a microporous film of an olefin-based resin such as polyethylene / polypropylene can be used alone or in combination. It is generally used as a preferred embodiment. The thickness of the separator as the porous insulator 3 is not particularly limited, but may be 10 to 25 μm.

About the non-aqueous secondary battery comprised as mentioned above, the operation | movement and an effect | action are demonstrated below. The non-aqueous electrolyte injected into the non-aqueous secondary battery is easily injected into the gap formed between the electrode group 4 and the battery case 5 and in the central portion of the electrode group 4, and the non-aqueous electrolyte injected into the gap The aqueous electrolyte solution is impregnated into the central portion of the negative electrode mixture layer 13 through the exposed portions of the outer peripheral side end portion and the inner peripheral side end portion of the electrode group 4 of the negative electrode mixture layer 13. At this time, the thickness of the outer peripheral side end and the inner peripheral side end of the electrode group 4 of the negative electrode mixture layer 13 is made thinner than the thickness of the negative electrode mixture layer 13 other than the outer peripheral end and inner peripheral side end. Since the outer peripheral side end and inner peripheral side end of the electrode group 4 of the negative electrode mixture layer 13 are not covered with the surface layer 14, the outer peripheral side end and inner peripheral side end of the negative electrode mixture layer 13 and the separator 3. The electrolyte injection path formed between the two can be formed widely, and the impregnation of the electrolyte into the central portion of the negative electrode mixture layer 13 can be promoted.

  Further, the non-aqueous electrolyte solution impregnated in the central portion of the negative electrode mixture layer 13 tries to move to the outside of the negative electrode mixture layer 13 through the surface of the negative electrode mixture layer 13. Since the surface of the negative electrode mixture layer 13 other than the end portions is covered with a surface layer 14 that is less impregnated than the negative electrode mixture layer 13, the nonaqueous electrolytic solution once impregnated inside the negative electrode mixture layer 13. Does not easily move out of the surface layer 14 and can continue to be retained in the negative electrode mixture layer 13, thereby preventing liquid withering.

Furthermore, since there is no bulge of the edge part of the negative mix layer 13 like the past, productivity can be improved.
(Embodiment 2)
FIG. 4 is a schematic view of a cross section of the negative electrode plate 2 for a non-aqueous secondary battery according to the second embodiment of the present invention. The negative electrode plate 2 is formed by forming a negative electrode mixture layer 13 containing a negative electrode active material on the surface of a negative electrode current collector 12. At this time, as in the first embodiment, the thickness of the end portion of the negative electrode mixture layer 13 is configured to become thinner toward the end portion of the negative electrode mixture layer 13, and as shown in FIG. The length X that becomes thinner toward the end of the agent layer 13 is configured such that the ratio to the thickness Z of the negative electrode mixture layer 13 is 1 or less. Further, in the present embodiment, the application start position Y of the surface layer 14 is configured to be smaller than X. That is, a surface layer 14 having a lower impregnation property than the negative electrode mixture layer 13 is applied to the surface of the mixture layer 13 excluding a part of the surface of both end portions of the negative electrode mixture layer 13. A part of the surface of the layer 13 is exposed. The negative electrode plate for a non-aqueous secondary battery configured as described above improves the impregnation property and liquid retention property of the non-aqueous electrolyte solution into the negative electrode mixture layer 13 as in the first embodiment, and has a battery capacity. And improve productivity.

  Furthermore, although the thickness of the both ends of the negative electrode mixture layer 13 in the longitudinal direction of the negative electrode plate is configured to be thinner than the portions other than the both ends, the negative electrode mixture in the width direction of the negative electrode plate 2 as shown in FIG. You may comprise so that the thickness of the both ends of the agent layer 13 may become thinner than parts other than both ends. At this time, a portion where the negative electrode mixture layer 13 is applied and a portion where the negative electrode mixture layer 13 is not applied are provided, and the negative electrode mixture layer 13 is not applied in the width direction of the negative electrode current collector 12. The lead 7 may be joined.

  In the present embodiment, the electrode group 4 is formed by interposing the porous insulator 3 between the positive electrode plate 1 and the negative electrode plate 2 and winding it in a spiral shape. Good.

  Further, in the present embodiment, the example in which the surface layer 14 is formed on the negative electrode mixture layer 13 is shown, but the positive and negative electrodes may be formed to form the surface layer.

Hereinafter, an embodiment of a nonaqueous secondary battery electrode plate 2 and a nonaqueous secondary battery using the same according to the present invention will be described.
Example 1
Example 1 in which a nonaqueous secondary battery 11 using a negative electrode plate having the same structure as that shown in FIG. 2 was produced will be described.

First, 100 parts by weight of artificial graphite as a negative electrode active material, and 2.5 parts by weight of styrene-butadiene copolymer rubber particle dispersion (solid content 40% by weight) as a binder with respect to 100 parts by weight of the negative electrode active material ( 1 part by weight in terms of solid content of the binder), 1 part by weight of carboxymethyl cellulose as a thickener with respect to 100 parts by weight of the negative electrode active material, and an appropriate amount of water, and agitation in a double arm kneader. A mixture paint was prepared. Further, 100 parts by weight of lithium titanium composite oxide as the active material of the surface layer 14 and 100 parts by weight of the active material of the surface layer of styrene-butadiene copolymer rubber particle dispersion (solid content 40% by weight) as the binder. 2.5 parts by weight (1 part by weight in terms of solid content of the binder), carboxymethyl cellulose as a thickener, 1 part by weight with respect to 100 parts by weight of the active material of the surface layer 14, and acetylene black as a conductive material The mixture was stirred with a double-arm kneader together with 3.0 parts by weight of water and 100 parts by weight of the surface layer active material to prepare a surface layer paint. First, a negative electrode mixture paint is applied to and dried on a negative electrode current collector 12 made of a copper foil having a thickness of 10 μm, and then the surface layer paint is applied to the surface layer portion of the negative electrode mixture paint with respect to 100 parts by weight of the negative electrode mixture layer. It was coated and dried to 20 parts by weight, and pressed so that the surface layer thickness was 20 μm, the mixture layer thickness was 180 μm, and the total thickness was 200 μm, and the negative electrode plate 2 was produced.
At this time, the thickness of both end portions of the negative electrode mixture layer 13 in the longitudinal direction of the negative electrode plate is configured to become thinner toward the end portion of the negative electrode mixture layer 13, and the surface of both end portions of the negative electrode mixture layer 13 is excluded. A surface layer 14 having a lower impregnation property than the negative electrode mixture layer 13 is applied to the surface of the negative electrode mixture layer 13. The thickness of both ends of the negative electrode mixture layer 13 in the longitudinal direction of the negative electrode plate is set so that the length X that becomes thinner toward the end of the negative electrode mixture layer 13 becomes 500 μm by adjusting the coating pressure. The ratio with respect to the thickness of 180 μm was set to 1 or less. Furthermore, the application | coating start position of the surface layer 14 was 700 micrometers, and it apply | coated so that the both ends of the negative mix layer 13 might be exposed, and the negative electrode plate 2 was obtained.

  Meanwhile, 100 parts by weight of lithium cobaltate as a positive electrode active material, 2 parts by weight of acetylene black as a conductive material with respect to 100 parts by weight of the positive electrode active material, and polyvinylidene fluoride as a binder with respect to 100 parts by weight of the positive electrode active material. A positive electrode mixture paint was prepared by stirring and kneading 2 parts by weight with an appropriate amount of N-methyl-2-pyrrolidone in a double-arm kneader. This paint was applied to a positive electrode current collector made of an aluminum foil having a thickness of 15 μm, dried, and pressed to a total thickness of 170 μm.

Further, as shown in FIG. 1, the positive electrode plate 1 and the negative electrode plate 2 are wound using a polyethylene microporous film having a thickness of 20 μm as a separator as a porous insulator 3 to form an electrode group 4, which has a predetermined length. Cut and inserted into the battery case 5 and sealed by adding 5.5 g of non-aqueous electrolyte in which 1 part of LiPF6 and 3 parts by weight of VC are dissolved in an EC / DMC / MEC mixed solvent. The lithium ion secondary battery 11 was taken as Example 1.
(Example 2)
The difference from Example 1 is that one end of the negative electrode mixture layer on the inner peripheral side of the electrode group 4 is applied so that it is completely covered with the surface layer provided on the surface layer part, and the negative electrode mixture layer on the outer peripheral side of the electrode group 4 That is, the negative electrode plate 2 whose 13 end portions are not covered with the surface layer 14 is obtained.
100 parts by weight of a negative electrode mixture layer formed by preparing a negative electrode mixture paint and a surface layer paint in the same manner as in Example 1, and applying and drying the mixture paint onto a negative electrode current collector 12 made of a copper foil having a thickness of 10 μm. Then, the surface layer coating was applied and dried so as to be 20 parts by weight, and pressed so that the surface layer thickness was 20 μm, the mixture layer thickness was 180 μm, and the total thickness was 200 μm.

On the other hand, a positive electrode plate 1 similar to that in Example 1 was produced, and a cylindrical lithium ion secondary battery 11 in which these positive electrode plate 1 and negative electrode plate 2 were produced in the same manner as in Example 1 was used as Example 2.
At this time, the one end part where the negative electrode mixture layer 13 is completely covered with the surface layer 14 is formed so as to be on the inner peripheral side when the electrode group 4 is formed, and the battery is cut by a predetermined length. The cylindrical lithium ion secondary battery 11 inserted into the case 5 and sealed by adding 5.5 g of a non-aqueous electrolyte was used as Example 2.
Example 3
The difference from Example 1 is that one end portion of the negative electrode mixture layer 13 on the outer peripheral side of the electrode group 4 is applied so as to be completely covered with the surface layer provided on the surface layer portion, and the negative electrode mixture on the inner peripheral side of the electrode group 4 That is, the negative electrode plate 2 in which the end portion of the layer 13 is not covered with the surface layer 14 is obtained.
100 parts by weight of a negative electrode mixture layer formed by preparing a negative electrode mixture paint and a surface layer paint in the same manner as in Example 1, and applying and drying the mixture paint onto a negative electrode current collector 12 made of a copper foil having a thickness of 10 μm. Then, the surface layer coating was applied and dried so as to be 20 parts by weight, and pressed so that the surface layer thickness was 20 μm, the mixture layer thickness was 180 μm, and the total thickness was 200 μm.

On the other hand, a positive electrode plate 1 similar to that in Example 1 was produced, and a cylindrical lithium ion secondary battery 11 in which these positive electrode plate 1 and negative electrode plate 2 were produced in the same manner as in Example 1 was used as Example 2.
At this time, one end of the negative electrode mixture layer 13 that is completely covered with the surface layer 14 is configured to be on the outer peripheral side when the electrode group 4 is formed, and is cut to a predetermined length to form a battery case. Example 3 was a cylindrical lithium ion secondary battery 11 that was inserted into 5 and sealed by adding 5.5 g of a non-aqueous electrolyte.
Example 4
A non-aqueous secondary battery using the negative electrode plate 2 having the same structure as that shown in FIG. 4 was produced. A negative electrode mixture paint and a surface layer paint are produced in the same manner as in Example 1, and the negative electrode mixture paint is formed on the negative electrode current collector 12 made of a copper foil having a thickness of 10 μm. These paints are applied at the same time before drying so that the surface layer paint is 20 parts by weight, and then dried, then pressed so that the surface layer thickness is 20 μm, the mixture layer thickness is 180 μm, and the total thickness is 200 μm. Then, the negative electrode plate 2 was prepared.

  At this time, the length X of the negative electrode plate 2 that decreases toward the end of the negative electrode mixture layer 13 is set to 500 μm by adjusting the coating pressure, and the ratio of the negative electrode mixture layer 13 to the thickness of 180 μm is 1. It comprised so that it might become the following. Furthermore, the application | coating start position of the surface layer 14 was 200 micrometers, and it apply | coated so that a part of both ends of the negative mix layer 13 might be exposed, and the negative electrode plate 2 was obtained.

On the other hand, a positive electrode plate 1 similar to that in Example 1 was produced, and a cylindrical lithium ion secondary battery 11 in which these positive electrode plate 1 and negative electrode plate 2 were produced in the same manner as in Example 1 was used as Example 4.
(Comparative Example 1)
FIG. 6 is a schematic view of a cross section of the negative electrode plate 2 for a non-aqueous secondary battery in a comparative example, which is formed by applying and drying the surface layer 14 on the negative electrode current collector 12. At this time, the surface layer 14 is formed on the surface layer portion of the negative electrode mixture layer 13 as in FIG. 2, but FIG. 6 shows both end portions of the negative electrode mixture layer 13 by shifting the timing when the surface layer 14 is applied. Is completely covered with the surface layer 14.

  A negative electrode mixture paint and a surface layer paint were prepared in the same manner as in Example 1. The paint was applied to a negative electrode current collector 12 made of 10 μm thick copper foil, and pressed to a total thickness of 200 μm. As shown in FIG. 6, the negative electrode plate 2 in which both end portions of the negative electrode mixture layer 13 were completely covered with the surface layer 14 was obtained.

  On the other hand, a positive electrode plate 1 similar to that in Example 1 was produced, and a cylindrical lithium ion secondary battery 11 in which these positive electrode plate 1 and negative electrode plate 2 were produced in the same manner as in Example 1 was used as Comparative Example 1.

  Here, as shown in FIG. 1, the evaluation method of the liquid injection property of the non-aqueous secondary battery in Examples 1 to 4 and Comparative Example 1 was obtained by forming the positive electrode plate 1 and the negative electrode plate 2 into a 20 μm thick polyethylene microporous film Is wound as a separator as a porous insulator 3 to form an electrode group 4, cut to a predetermined length and inserted into the battery case 5, and 1M and VC of LiPF6 are mixed in an EC / DMC / MEC mixed solvent. The time until the electrode group 4 was impregnated with the nonaqueous electrolytic solution was evaluated as the injection time after 5.5 g in total of 3 parts by weight of the dissolved nonaqueous electrolytic solution (not shown) were divided and added. . And the battery capacity evaluation was performed about the cylindrical lithium ion secondary battery 11 created on said conditions.

  The contents evaluated for the above items are shown in (Table 1).

  As shown in Table 1, it was found that the liquid injection time was the shortest when both end portions of the negative electrode mixture layer 13 were exposed from the surface layer 14. This is because the liquid injection property of the negative electrode mixture layer 13 is higher than that of the surface layer 14, and the end of the negative electrode mixture layer 13 is exposed, so that a nonaqueous electrolyte injection path can be secured. It can be presumed that the time for injecting the non-aqueous electrolyte solution was shortened by improving the impregnation property of the non-aqueous electrolyte solution. Furthermore, since the impregnation property was promoted and the nonaqueous electrolyte solution had good liquid retention, the battery capacity was also increased.

  On the other hand, as shown in Comparative Example 1, when the end portion was covered with the surface layer 14, the liquid injection time was about four times that of the Example, the productivity was lowered, and the battery capacity was also lowered.

As described above, by exposing the end portion of the negative electrode mixture layer 13 from the surface layer 14, the impregnation property of the nonaqueous electrolytic solution into the negative electrode plate 2, that is, the liquid injection property is improved and improved, thereby increasing the battery capacity. , Productivity is also greatly improved.
In Examples 1 to 4, the end of the negative electrode mixture layer 13 of the negative electrode plate 2 was exposed from the surface layer 14 to improve the impregnation property and liquid retention of the nonaqueous electrolytic solution. For example, the same effect can be obtained by providing a surface layer on the positive electrode mixture layer of the positive electrode plate 1 and exposing the end portion of the positive electrode mixture layer to improve the impregnation property and liquid retention. Can be obtained.

  The electrode plate for a non-aqueous secondary battery according to the present invention is impregnated with a non-aqueous electrolyte into the electrode plate from a conventional non-aqueous secondary battery by exposing an end portion of the electrode mixture layer from the surface layer. The non-aqueous electrolyte solution retention and injection properties of the electrode group are improved, and the capacity and productivity are excellent, so it can be used for multifunctional electronic devices and communication devices and for applications in electric vehicles. Along with this, it is useful as a portable power supply, EV power supply, etc. for which high capacity and low cost are desired.

DESCRIPTION OF SYMBOLS 1 Positive electrode plate 2 Negative electrode plate 3 Porous insulator 4 Electrode group 5 Battery case 6 Insulating plate 7 Negative electrode lead 8 Positive electrode lead 9 Sealing plate 10 Sealing gasket 11 Lithium ion secondary battery 12 Negative electrode collector 13 Negative electrode mixture layer 14 Surface layer

Claims (6)

In the battery electrode plate in which the mixture layer containing the active material is formed on the surface of the current collector, the thickness of the end portion of the mixture layer is made thinner than the thickness other than the end portion of the mixture layer, and at least A non-aqueous secondary battery characterized in that the surface of the mixture layer is covered with a surface layer having a lower impregnation property than the mixture layer so as to expose a part of the end portion of the mixture layer. Electrode plate. 2. The electrode plate for a non-aqueous secondary battery according to claim 1, wherein the thickness of the end portion of the mixture layer is reduced toward the end portion of the mixture layer. 3. The non-aqueous system according to claim 1, wherein the end portion of the mixture layer is either one of both end portions of the mixture layer in the longitudinal direction of the electrode plate or the both end portions. Secondary battery electrode plate. 3. The non-aqueous system according to claim 1, wherein the end portion of the mixture layer is either one of both end portions of the mixture layer in the electrode plate width direction or the both end portions. Secondary battery electrode plate. The surface layer is different from the active material of the mixture layer, such as a nickel-based composite oxide such as lithium nickel acid composite oxide, a cobalt-based composite oxide such as lithium cobalt acid composite oxide, cobalt acid nanoparticles, and cobalt oxynitride , Manganese complex oxides such as lithium manganate complex oxides, chromium complex oxides such as lithium chromate complex oxides, iron phosphate complex oxides such as lithium iron phosphate complex oxides, vanadium pentoxide 5. The use of any one of vanadium-based composite oxides such as graphite, hard carbon, lithium-based composite oxides such as lithium-titanium composite oxide, tin oxide glass, silica-based alloy composition material, and metallic lithium. Electrode plate for non-aqueous secondary battery. A positive electrode plate having a positive electrode mixture layer formed by adhering a positive electrode mixture coating material obtained by kneading and dispersing a positive electrode active material comprising at least a lithium-containing composite oxide, a conductive material, and a binder in a dispersion medium onto a positive electrode current collector And a negative electrode active material made of a material capable of holding at least lithium, and a negative electrode plate carrying a negative electrode current collector on a negative electrode plate. In a non-aqueous secondary battery encapsulated in an outer package together with an aqueous electrolyte, the electrode plate for a non-aqueous secondary battery according to any one of claims 1 to 5 is used for the positive electrode plate and the negative electrode plate. A non-aqueous secondary battery.