JP2009283270A - Electrode plate for nonaqueous secondary battery and method of manufacturing the same, and nonaqueous secondary battery using the electrode plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode plate for a nonaqueous secondary battery, in which: sagging is suppressed which occurs on an end face of the electrode mixture layer of the nonaqueous secondary battery electrode plate when the electrode mixture coating is continuously or intermittently applied on the surface of a current collector, dried and rolled to form the electrode mixture layer; decrease of an ion reaction area can be prevented; and a utilization rate of the electrode mixture layer is improved. <P>SOLUTION: A water-repellent material 16 is applied to the current collector 1 at positions corresponding to the electrode mixture layer 2 formed with the electrode mixture coating and the uncoated parts 19 of the electrode mixture coating so that the saggings occurring on the end faces of the electrode mixture layer 2 of the nonaqueous secondary battery electrode plate are suppressed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrode plate for a non-aqueous secondary battery represented by a lithium ion secondary battery having particularly improved battery capacity, a method for producing the same, and a non-aqueous secondary battery using the electrode plate for a non-aqueous secondary battery. The present invention relates to a secondary battery.

Lithium ion secondary batteries, which are widely used as power sources for portable electronic devices, use a carbonaceous material capable of occluding and releasing lithium for the negative electrode plate, and a composite of a transition metal such as LiCoO ₂ and lithium for the positive electrode plate An oxide is used as an active material, and this has realized a lithium-ion secondary battery as a non-aqueous secondary battery with a high potential and a high discharge capacity. Along with this, further increase in capacity is desired. By stabilizing the surface condition of the electrode mixture layer of the positive electrode plate and the negative electrode plate of these lithium ion secondary batteries, it is extremely possible to stabilize the movement of ions of the positive electrode plate and the negative electrode plate and to stabilize the battery capacity. is important.

  Conventionally, as one of the problems, a method of applying an electrode mixture paint to a current collector when forming an electrode mixture layer of a positive electrode plate and a negative electrode plate is generally used. The electrode mixture paint 42 is applied to the current collector 41 as shown in FIG. 7 when the electrode mixture paint 42 and the current collector 41 are applied. The film thickness of the electrode mixture paint 42 is not uniform at the boundary, and sagging occurs. When a lithium ion secondary battery is configured using an electrode plate in which sagging of the electrode mixture paint 42 is generated, there arises a problem that the battery capacity decreases due to a decrease in the reaction area of ions.

  In response to the above problems, various proposals have been made as means for suppressing the uniform film thickness and sagging of the electrode mixture paint. For example, FIG. 8 shows a process of manufacturing an electrode plate, and an active material and a solvent. Are mixed and dispersed, and then further mixed. After applying the mixed electrode mixture paint to the current collector, the electrode plate layer can be smoothed and dried by increasing the fluidity by applying ultrasonic vibration or low frequency vibration to the electrode plate. It has been proposed (see, for example, Patent Document 1).

Further, for example, FIGS. 9A, 9B, and 9C are cross-sectional views when the electrode mixture paint 51 is applied in the longitudinal direction of the current collector 50. First, FIG. As shown in FIG. 9B, a strip-shaped masking tape 52 having an adhesive layer is applied in the longitudinal direction of the current collector 50, an electrode mixture paint 51 is applied, and a long coating is applied as shown in FIG. The product is rolled to form the electrode mixture layer 53. Next, the masking tape 52 affixed to the long coating material is peeled in the longitudinal direction together with the electrode mixture layer 53 on the masking tape 52, and the current collector is collected as shown in FIG. It has been proposed to form an electrode mixture layer 53 with less sagging on the body 50 (see, for example, Patent Document 2).
JP 2006-40548 A JP 2005-183181 A

  However, the fluidity of the electrode mixture paint is improved by the method of uniforming the film thickness of the electrode mixture layer by applying ultrasonic vibration or low frequency vibration to the electrode plate of the prior art in Patent Document 1 described above. Therefore, there is an effect of making the film thickness of the electrode mixture layer other than the end face uniform, but it is extremely difficult to suppress the sagging at the boundary between the electrode mixture paint and the current collector.

  Moreover, in the method of making the film thickness of an electrode mixture layer uniform with the masking tape of the prior art in patent document 2 mentioned above, the problem that a part of electrode mixture layer falls off when peeling a masking tape generate | occur | produces. . In addition, it is extremely difficult to apply the electrode mixture paint on the masking tape so that it does not adhere to the masking tape. Loss of the electrode mixture paint adhering to the masking tape occurs, and the masking tape material cost and masking tape application The problem is that a peeling process is required.

  The present invention has been made in view of the above-described conventional problems, and is a non-aqueous system in which a water-repellent material that prevents sagging of the end surface of the electrode mixture layer is applied to a position corresponding to the uncoated portion of the electrode mixture paint of the current collector. It aims at providing the electrode plate for secondary batteries.

  In order to achieve the above-mentioned object, the electrode plate for a non-aqueous secondary battery of the present invention is a non-aqueous secondary battery in which an electrode mixture paint is applied to the surface of a current collector continuously or intermittently and dried to form an electrode mixture layer. The electrode plate for an aqueous secondary battery is characterized in that a water-repellent material that prevents sagging of the end face of the electrode mixture layer is applied to a position corresponding to an uncoated portion of the electrode mixture paint of the current collector.

  According to the electrode plate for a non-aqueous secondary battery of the present invention, by using the electrode plate that suppresses the sagging of the end surface of the electrode mixture layer and improves the utilization rate of the electrode mixture layer for the non-aqueous secondary battery. It is possible to stabilize the battery capacity with a high capacity.

  In the first invention of the present invention, in an electrode plate for a non-aqueous secondary battery in which an electrode mixture paint is applied to the surface of a current collector continuously or intermittently and dried to form an electrode mixture layer. By applying a water-repellent material that prevents sagging of the end face of the electrode mixture layer to a position corresponding to the uncoated part of the electrode mixture paint of the electric body, the electrode plate utilization rate is improved, and the battery capacity is increased with high capacity. Can be stable.

  In the second invention of the present invention, the use of the water-repellent film as the water-repellent substance has the effect of improving the interfacial tension of the current collector and improving the contact angle of the electrode mixture paint.

  In the third aspect of the present invention, the water-repellent tape used as the water-repellent substance allows the water-repellent tape attached to the current collector to accurately match the dimensions of the boundary between the current collector and the electrode mixture layer. It is possible to reduce the variation in the reaction area of the electrode mixture layer, suppress the variation in the capacity, and suppress the sagging.

  In the fourth invention of the present invention, the sagging of the four end faces of the electrode mixture layer is suppressed by applying the water repellent material to the entire uncoated portion of the electrode mixture layer applied intermittently. Is possible.

  In the fifth invention of the present invention, a non-aqueous system in which an electrode mixture coating comprising at least an active material and a binder is applied intermittently or continuously to the surface of a current collector and dried to form an electrode mixture layer In the method for manufacturing an electrode plate for a secondary battery, a water repellent material that prevents sagging of the end surface of the electrode mixture layer is applied to a position corresponding to an uncoated portion of the electrode mixture paint of the current collector, and then the electrode mixture paint is applied. By applying, sagging of the end surface of the electrode mixture layer can be suppressed.

In the sixth aspect of the present invention, the water-repellent solution is sprayed and applied as a water-repellent substance so that the water-repellent solution is volatilized and removed in the drying step after the electrode mixture paint is applied to the current collector. Therefore, it is possible to manufacture an electrode plate with less influence on battery characteristics due to the remaining adhesion of the water-repellent solution.

  In the seventh aspect of the present invention, by spraying and applying the water-repellent solution in a heated state, the dispersibility at the time of applying the water-repellent solution is improved, and the water-repellent solution can be uniformly applied to the current collector. It is.

  According to an eighth aspect of the present invention, there is provided a non-aqueous secondary battery in which an electrode group comprising a positive electrode plate, a negative electrode plate, a laminate or a wound body of a separator is enclosed in a case together with a non-aqueous electrolyte. A water-repellent material that prevents sagging of the end surface of the electrode mixture layer is applied at a position corresponding to the uncoated portion of the electrode mixture paint, and the electrode mixture paint is applied continuously or intermittently to the surface of the current collector. By using the electrode plate for a non-aqueous secondary battery according to any one of claims 1 to 4 which is dried to form an electrode mixture layer as at least one of a positive electrode plate or a negative electrode plate, It is possible to stabilize the battery capacity in terms of capacity.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, FIG. 1 shows a cross-sectional view of the electrode plate 18 showing the end face of the electrode mixture layer 2 in the present invention, but at a position corresponding to the uncoated portion 19 of the electrode mixture paint on the front and back of the current collector 1. By applying the water repellent material 16, it is possible to suppress sagging of the end surface of the electrode mixture layer 2. By using this electrode plate as the non-aqueous secondary battery of the present invention shown in FIG. 6, it is possible to constitute a non-aqueous secondary battery having a high capacity and a stable battery capacity. That is, after producing an electrode group 26 in which a positive electrode plate 20 using a composite lithium oxide as an active material and a negative electrode plate 21 using a material capable of holding lithium as an active material are spirally wound through a separator 22, The electrode group 26 is accommodated inside the bottomed cylindrical battery case 23 together with the insulating plate 29, the negative electrode lead 28 led out from the lower part of the electrode group 26 is connected to the bottom part of the battery case 23, and then the upper part of the electrode group 26 After connecting the positive lead 27 led out to the sealing plate 24 and injecting a predetermined amount of an electrolyte solution (not shown) made of a non-aqueous electrolyte into the battery case 23, a sealing gasket 25 is attached to the opening of the battery case 23. A sealing plate 24 attached to the periphery is inserted, and the opening of the battery case 23 is folded inward to seal by caulking. The positive electrode plate 20 or the negative electrode plate 21 is an electrode plate of the present invention that suppresses sagging of the end surface of the electrode mixture layer 2.

  FIG. 2 shows an apparatus for applying an electrode mixture paint to the current collector 1. The electrode mixture paint conveyed through the pipe 5 passes through the paint valve 4 and the pipe 6 and is supplied to the coating die 3. Is done. On the other hand, the water repellent made of fluororesin or fluororubber as the water repellent material 16 conveyed via the pipe 10 is applied with the electrode mixture paint by the water repellent application brush 8 via the water repellent valve 9. Immediately before being applied, the current collector 1 is applied to a position corresponding to the uncoated portion 19 of the electrode mixture paint, and the current collector 1 is wound around the backup roller 7 and conveyed. When applying a water repellent to the current collector 1, a brush, a brush, or cotton may be used. An electrode mixture layer 2 is formed on the current collector 1 by applying an electrode mixture paint to the current collector 1 and drying it. The paint valve 4 is an apparatus for intermittently supplying the electrode mixture paint, and can be stably supplied according to the coating speed and the application area.

  Further, FIG. 3 is a device similar to the device of FIG. 2, in which a water repellent tape made of fluororesin or fluororubber as a water repellent material is attached to the current collector 1, but supplied from a water repellent tape unwinding roll 12. The water-repellent tape 11 is pasted on the current collector 1 with a water-repellent tape pasting roller 13. Thereafter, the electrode mixture paint is applied to the current collector 1 with the coating die 3, and then the water repellent tape 11 is again peeled off by the peeling roller 14 and collected by the water repellent tape winding roll 15. The feed speed and width of the water repellent tape 11 can be switched according to the coating speed and the coating area. Further, the water repellent tape 11 may be peeled off immediately after applying the electrode mixture paint to the current collector 1 or after drying.

4 is an apparatus for spraying a water repellent solution made of a fluorine-based material as the water repellent substance 16 onto the current collector 1 as in the apparatus of FIG. The water-repellent solution as the substance 16 passes through the water-repellent valve 9 and the current collector 1 by the water-repellent solution application nozzle 17.
The current collector 1 is wound around the backup roller 7, applied with an electrode mixture paint, and conveyed. For example, FIG. 5A shows a plan view of an electrode plate 18 in which an electrode mixture paint is continuously applied to the current collector 1. When the electrode mixture paint is applied continuously, the water repellent material 16 is applied in parallel to the application direction. For example, as shown in FIG. 5B, the electrode mixture paint is applied intermittently to the current collector 1. In this case, the sagging of the end surface can be suppressed by applying the water repellent material 16 to the entire uncoated portion in the direction perpendicular to the coating direction.

  Next, a method for producing the positive electrode plate 20 and the negative electrode plate 21 will be specifically described. First, the positive electrode plate 20 is not particularly limited, but a foil made of aluminum or an aluminum alloy can be used, and a positive electrode active material, a conductive material, a binder are formed on one or both sides of a positive electrode current collector having a thickness of 10 μm or more and 40 μm or less. It is produced by forming a positive electrode mixture layer by water-repellent treatment, application, drying and rolling of a positive electrode mixture paint obtained by mixing and dispersing an agent in a dispersion medium with a dispersing machine such as a planetary mixer.

  Examples of the positive electrode active material include lithium cobaltate and modified products thereof (such as lithium cobaltate in which aluminum or magnesium is dissolved), lithium nickelate and modified products thereof (such as nickel partially 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 binder for the positive electrode at this time, 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. At this time, an acrylate monomer or an acrylate oligomer into which a reactive functional group is introduced can be mixed in the binder.

  On the other hand, the negative electrode plate 21 is not particularly limited, but a foil made of copper or a copper alloy can be used, and a negative electrode active material, a binder, and a negative electrode current collector having a thickness of 10 μm to 40 μm. A negative electrode mixture layer is formed by water-repellent treatment, coating, drying, and rolling a negative electrode mixture paint in which a conductive material and thickener are mixed and dispersed in a dispersion medium such as a planetary mixer as needed. It is produced by doing.

  As the negative electrode active material, various natural graphites, artificial graphite, 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 negative electrode binder at this time. From the viewpoint of improving lithium ion acceptability, styrene-butadiene copolymer rubber particles (SBR) and modified products thereof are used. Etc. can also be used.

  Next, the separator is not particularly limited as long as it has a composition that can withstand the use range of the lithium ion secondary battery, but a microporous film of an olefin resin such as polyethylene or polypropylene is generally used singly or in combination. And preferred as an embodiment. The thickness of the separator is not particularly limited, but may be 10 to 25 μm.

Moreover, for the electrolytic solution as the non-aqueous electrolyte, it is possible to use various lithium compounds such as LiPF ₆ and LiBF ₄ as an 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 / negative electrode plates or to ensure stability during overcharge.

  Hereinafter, specific embodiments of the present invention will be described in more detail with reference to the drawings. A device for applying an electrode mixture paint to the current collector 1 of FIG. 2 is used, a water repellent film using a fluororesin is formed on the end face of the current collector 1, and the electrode mixture paint is applied to the electrode mixture. The electrode plate on which the layer 2 was formed was designated as Example 1.

  A device for applying an electrode mixture paint to the current collector 1 in FIG. 3 is used. A water repellent tape 11 using a fluororesin is attached to the end face of the current collector 1, and the electrode mixture paint is applied to the electrode mixture. The electrode plate on which the layer 2 was formed was designated as Example 2.

  A device for applying an electrode mixture paint to the current collector 1 of FIG. 2 is used. A fluorine-based water-repellent solution is sprayed on the end face of the current collector 1, and the electrode mixture paint is applied to the electrode mixture layer 2. An electrode plate obtained by molding was used as Example 3.

  Using a device for applying an electrode mixture paint to the current collector 1 in FIG. 2, spraying a fluorine-based water-repellent solution heated to 35 ° C. on the end face of the current collector 1, and applying the electrode mixture paint An electrode plate on which the electrode mixture layer 2 was formed was referred to as Example 4.

(Comparative Example 1)
The electrode plate in which the electrode mixture layer 2 was formed by applying the electrode mixture paint without forming the water repellent film on the current collector 1 was used as Comparative Example 1.

  As an evaluation method of the sagging of the electrode mixture paint, the sagging of the end face when the electrode mixture paint was applied to about 80 μm on one side at a coating speed of 20 m / min using the electrode mixture paint of the same lot was compared. Also, the sagging of the end face is measured by measuring the film thickness from the end face of the coating from 0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm to the end face on the opposite side, and the end position relative to the central part 100%. The thickness ratio was calculated as the sagging rate. The battery capacity was evaluated by preparing five non-aqueous secondary batteries each using the electrode plates of Examples 1, 2, 3, 4 and Comparative Example 1, and calculating the average battery capacity. The battery capacities of Examples 1, 2, 3, and 4 were calculated when the battery capacity was 100%.

In the result of Example 1, sagging of the end face of the electrode mixture layer could be suppressed as compared with Comparative Example 1 by applying a water repellent film to the current collector 1. Comparative Example 1 is 5 mm from the end face and the sagging rate is 100%, which is the same as the film thickness in the central portion, whereas Example 1 is 100% at 2 mm from the end face. The battery capacity was also improved to 104%. Moreover, in the result of Example 2, sagging of the end surface of the electrode mixture layer could be suppressed as compared with Comparative Example 1 by applying the water repellent tape 11 to the current collector 1. Example 2 becomes 100% at 2 mm from the end face. However, compared with Example 1, the thickness of the electrode mixture layer 2 near 1 mm from the end face is extremely reduced. This is because the mixture paint adheres to the water repellent tape 11 when the water repellent tape 11 is peeled off. This is thought to be the cause. Therefore, the battery dose was 102%, which was improved compared to Comparative Example 1, but was inferior to Example 1.

  In the result of Example 3, sagging of the end surface of the electrode mixture layer 2 was slightly suppressed as compared with Comparative Example 1 by applying a water repellent solution to the current collector 1. In Example 3, the sagging rate was 3% at 3 mm from the end face, and the battery capacity was 101%, which was slightly improved compared to Comparative Example 1. Further, in the result of Example 4, the current collector 1 was applied with a water repellent solution heated to 35 ° C., so that the end surface of the electrode mixture layer 2 was slightly more than that of the non-heated aqueous repellent solution 20 ° C. of Comparative Example 1. Sagging was suppressed. In Example 4, the sagging rate was 3% at 3 mm from the end face, and the battery capacity was 101%, which was slightly improved compared to Comparative Example 1. Compared to Example 3, even when the water-repellent aqueous solution was at a high temperature of 35 ° C., the sagging of the end face of the electrode mixture layer did not change as much as the difference.

  The electrode plate for a non-aqueous secondary battery according to the present invention is formed by applying a water repellent material that prevents sagging of the end surface of the electrode mixture layer to a position corresponding to the uncoated portion of the electrode mixture paint of the current collector. It is possible to suppress the sagging of the end surface of the agent layer, to make the film thickness of the electrode mixture paint uniform at the boundary between the electrode mixture paint and the current collector, and to improve the utilization rate of the electrode mixture layer In addition to portable power sources that are capable of configuring non-aqueous secondary batteries with high capacity and stable battery capacity, and which are desired to have higher capacities with the multifunctionalization of electronic devices and communication devices, It is also useful for nickel metal hydride batteries and capacitors.

Sectional drawing of the electrode plate which shows the end surface of the electrode mixture layer in this invention The schematic diagram which shows the apparatus which apply | coats an electrode mixture coating material to the electrical power collector which concerns on one embodiment in this invention The schematic diagram which shows another apparatus which applies an electrode mixture coating material to the electrical power collector which concerns on one embodiment in this invention The schematic diagram which shows another apparatus which applies an electrode mixture coating material to the electrical power collector which concerns on one embodiment in this invention (A) The top view of the electrode plate which applied the mixture paint continuously concerning one embodiment in the present invention, (b) The electrode plate which applied the mixture paint intermittently concerning one embodiment in the present invention Top view of 1 is a partially cutaway perspective view of a cylindrical secondary battery according to an embodiment of the present invention. Sectional drawing of the electrode plate which shows the sagging of the end surface of the electrode mixture layer in the past Process flow chart for manufacturing a conventional electrode plate (A) Cross-sectional view showing the manufacturing process of the electrode plate in the prior art, (b) Cross-sectional view showing the manufacturing process of the electrode plate in the prior art, (c) Cross-sectional view showing the manufacturing process of the electrode plate in the prior art

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Current collector 2 Electrode mixture layer 3 Coating die 4 Paint valve 5 Piping 6 Piping 7 Backup roller 8 Water repellent application brush 9 Water repellent valve 10 Piping 11 Water repellent tape 12 Water repellent tape unwinding roll 13 Water repellent Tape application roller 14 Water repellent tape peeling roller 15 Water repellent tape take-up roll 16 Water repellent material 17 Water repellent solution application nozzle 18 Electrode plate 19 Uncoated portion 20 Positive electrode plate 21 Negative electrode plate 22 Separator 23 Battery case 24 Sealing plate 25 Sealing Gasket 26 Electrode group 27 Positive electrode lead 28 Negative electrode lead 29 Insulating plate

Claims (8)

  In an electrode plate for a non-aqueous secondary battery in which an electrode mixture coating is formed by continuously or intermittently applying and drying an electrode mixture coating on the surface of a current collector to form an electrode mixture layer, the electrode mixture coating of the current collector is not yet applied. An electrode plate for a non-aqueous secondary battery, wherein a water repellent material that prevents sagging of the end face of the electrode mixture layer is applied to a position corresponding to the application part.   The electrode plate for a non-aqueous secondary battery according to claim 1, wherein a water-repellent film is used as the water-repellent substance.   The electrode plate for a non-aqueous secondary battery according to claim 1, wherein a water-repellent tape is used as the water-repellent substance.   2. The electrode plate for a non-aqueous secondary battery according to claim 1, wherein the water repellent material is applied to the entire uncoated portion of the electrode mixture layer that is intermittently applied.   In a method for producing an electrode plate for a non-aqueous secondary battery, in which an electrode mixture paint comprising at least an active material and a binder is intermittently or continuously applied to the surface of a current collector and dried to form an electrode mixture layer A non-aqueous system characterized in that the electrode mixture paint is applied after applying a water repellent material that prevents sagging of the end face of the electrode mixture layer to a position corresponding to an uncoated portion of the electrode mixture paint of the current collector A method for producing an electrode plate for a secondary battery.   6. The method for producing an electrode plate for a non-aqueous secondary battery according to claim 5, wherein a water repellent solution is sprayed as the water repellent substance.   The method for producing an electrode plate for a non-aqueous secondary battery according to claim 6, wherein the water-repellent solution is sprayed and applied in a heated state.   In a non-aqueous secondary battery in which an electrode group consisting of a positive electrode plate, a negative electrode plate, a laminate of laminates or a wound body is enclosed in a case together with a non-aqueous electrolyte, an uncoated portion of the current collector electrode mixture paint The electrode mixture layer is formed by applying a water-repellent substance that prevents sagging of the end face of the electrode mixture layer to a position corresponding to the surface of the current collector and applying the electrode mixture paint continuously or intermittently to the surface of the current collector and drying it. A non-aqueous secondary battery using the electrode plate for a non-aqueous secondary battery according to claim 1 as at least one of the positive electrode plate and the negative electrode plate.

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