JP2012185976A - Laminated battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated battery which can suppress variation in battery performance without using surplus members in the battery performance.SOLUTION: In the laminated battery having a laminate structure where a positive electrode P and a negative electrode N are laminated alternately while sandwiching a separator S, the negative electrode N is larger than the positive electrode P, and the difference in sizes of the negative electrode N and the positive electrode P is set based on the positioning accuracy of the negative electrode N and the positive electrode P when they are laminated, and the electric capacitance between the negative electrode N and the positive electrode P at the edges thereof when the edge of the negative electrode N is shifted from the edge of the positive electrode P.

Description

  The present invention relates to a stacked battery.

  The form of the battery is roughly classified into a cylindrical battery and a stacked battery, and the latter battery has a stacked structure in which rectangular positive electrodes and negative electrodes are alternately stacked with a separator interposed therebetween. Thus, when a battery is formed by stacking rectangular electrodes, it is preferable to use a separator having an area that is slightly larger than that of the electrodes in order to prevent a short circuit at the edges of the electrodes. However, when a separator having a size different from that of the electrode is used, it is difficult to position and stack adjacent electrodes with the separator interposed therebetween. In addition, if the position of the electrode is shifted, the battery performance varies.

  Patent Document 1 below discloses a stacked lithium-ion battery that can suppress cycle shift between electrodes and improve cycle characteristics. In this battery, when a plurality of laminated electrode bodies composed of a separator, a positive electrode, a separator, and a negative electrode are stacked, a misalignment prevention tape is applied so as to straddle each laminated electrode body to prevent movement of the electrodes. .

JP 2008-91099 A

  However, the above prior art requires an extra member in terms of battery performance, such as a slip prevention tape. Moreover, in the said prior art, the machine for affixing the tape for slippage prevention is also needed separately.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a stacked battery that can suppress variation in battery performance without using an extra member in battery performance.

In order to solve the above-described problems, the present invention provides a stacked battery having a stacked structure in which electrodes having different polarities are alternately stacked with separators in between, and has one of the electrodes. The first electrode is larger than the second electrode having the other polarity, and the difference in size between the first electrode and the second electrode is different from that of the first electrode and the second electrode when stacked. Positioning accuracy with the second electrode, and the first electrode and the second electrode at the edge when the edge of the first electrode is shifted from the edge of the second electrode The configuration is set based on the electric capacity between the electrodes.
By adopting this configuration, in the present invention, the first electrode is made larger than the second electrode on the basis of the positioning accuracy and the electric capacity, and the first electrode is not excessively enlarged, and after the stacking, All of the second electrodes are covered with one electrode to make the battery performance constant.

In the present invention, the first electrode is a negative electrode, and the second electrode is a positive electrode.
By adopting this configuration, in the present invention, the negative electrode whose material cost is relatively lower than that of the positive electrode is enlarged.

In the present invention, the negative electrode has an active material containing carbon on at least one surface, and the positive electrode has an active material containing a lithium compound on at least one surface.
By adopting this configuration, in the present invention, a negative electrode having an active material containing carbon whose material cost is lower than that of a positive electrode having an active material containing a lithium compound that is a rare metal is made larger.

According to the present invention, there is provided a stacked battery having a stacked structure in which electrodes having different polarities are alternately stacked with separators interposed therebetween, wherein the first electrode having one polarity is the other of the electrodes. The difference in size between the first electrode and the second electrode is larger than that of the second electrode having the polarity, and the positioning of the first electrode and the second electrode when the layers are stacked Accuracy and the electrical power between the first electrode and the second electrode at the edge when the edge of the first electrode is displaced with respect to the edge of the second electrode By adopting the configuration that is set based on the capacitance, the first electrode is made larger than the second electrode based on the positioning accuracy and the electric capacitance, and the first electrode is not excessively enlarged. Then, after lamination, cover all of the second electrode with the first electrode. To the battery performance constant.
Therefore, in the present invention, variations in battery performance can be suppressed without using extra members in battery performance.

It is a block diagram which shows the electrode lamination apparatus in embodiment of this invention. It is a top view which shows the laminated structure of the laminated battery in embodiment of this invention. It is a section lineblock diagram showing the lamination structure of the lamination type battery in the embodiment of the present invention. It is a figure for demonstrating the setting of the difference of the magnitude | size based on the positioning accuracy in embodiment of this invention. It is a figure for demonstrating the setting of the difference of the magnitude | size based on the electrical capacitance in embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
First, an electrode stacking apparatus for manufacturing a lithium secondary battery according to the stacked battery of the present invention will be described.

FIG. 1 is a configuration diagram illustrating an electrode stacking apparatus 1 according to an embodiment of the present invention.
The electrode stacking apparatus 1 has a positive electrode roll 2 that feeds out the positive electrode sheet PS. The positive electrode roll 2 has a configuration in which a positive electrode sheet PS of, for example, a metal foil having a thickness of about 8 to 20 μm, on which lithium-containing metal oxide is printed (attached) as an active material, is provided. The positive electrode sheet PS is formed by using, for example, an aluminum foil as a base material and arranging a powdery lithium-containing metal oxide on the surface of the base material.

  The electrode stacking apparatus 1 has a cutter device 3 that cuts out the positive electrode (second electrode) P from the positive electrode sheet PS on the downstream side of the positive electrode roll 2. The cutter device 3 cuts out the positive electrode P and cuts off part of one end in the width direction of the positive electrode sheet PS to form a tab of the positive electrode P. Note that the cut pieces fall onto the tray 4.

  The electrode stacking apparatus 1 includes a separator roll 11 that feeds out a separator sheet SS that supports the cut out positive electrode P on the downstream side of the cutter apparatus 3. The separator roll 11 is configured to feed out a separator sheet SS made of an insulating resin material having a thickness of about 8 to 25 μm, for example. The separator sheet SS is made of, for example, porous polyethylene or polyester.

  The electrode stacking apparatus 1 has an inspection camera 12 that inspects the positive electrode P on the separator sheet SS on the downstream side of the separator roll 11. The inspection camera 12 is configured to image the positive electrode P from above and transmit data acquired by the imaging to a control device (not shown). In a control device (not shown), the imaging data is subjected to image processing, and the posture and shape of the positive electrode P, the active material peeling, and the presence or absence of a defective state such as a hole are inspected.

  The electrode stacking apparatus 1 includes a separator roll 13 that feeds out a separator sheet SS that sandwiches the positive electrode P on the downstream side of the inspection camera 12. Similarly to the separator roll 11, the separator roll 13 is configured to feed out a separator sheet SS of an insulating resin material having a thickness of about 8 to 25 μm, for example.

  The electrode stacking apparatus 1 includes inspection cameras 14 and 15 that inspect upper and lower separator sheets SS sandwiching the positive electrode P on the downstream side of the separator roll 13. The inspection cameras 14 and 15 are configured to image the separator sheet SS and transmit data acquired by the imaging to a control device (not shown). In a control device (not shown), the imaged data is subjected to image processing and inspected for the presence or absence of a defective state such as the separator sheet SS being curled, wrinkled, or missing (pinhole or torn).

  The electrode stacking apparatus 1 has a heating and melting fixing device 16 that fixes the positive electrode P and the upper and lower separator sheets SS on the downstream side of the inspection cameras 14 and 15. The heat melting and fixing device 16 melts and bonds the upper and lower separator sheets SS by heating and fixes the positive electrode P in the sheet.

  The electrode laminating apparatus 1 has a cutter device 17 that cuts the separator sheet SS for each positive electrode P and forms a cell C composed of the separator S, the positive electrode P, and the separator S on the downstream side of the heating and melting and fixing device 16. The cutter device 17 has a heat cutter that burns off the separator sheet SS. The cell C formed by the cutting of the cutter device 17 is conveyed downstream by the conveyor device 20.

  The electrode stacking apparatus 1 has another line for cutting out the negative electrode N. On the other line of the electrode stacking apparatus 1, a negative electrode roll 22 for feeding out the negative electrode sheet NS is provided. The negative electrode roll 22 has a configuration in which a negative electrode sheet NS of a metal foil having a thickness of about 8 to 20 μm, for example, having a carbon material printed (attached) on both sides as an active material is fed out. The negative electrode sheet NS is formed by, for example, using copper foil as a base material and arranging powdery carbon on the surface of the base material.

  The electrode stacking apparatus 1 has a cutter device 23 that cuts out the negative electrode (first electrode) N from the negative electrode sheet NS on the downstream side of the negative electrode roll 22. The cutter device 23 cuts out the negative electrode N and cuts off part of one end in the width direction of the negative electrode sheet NS to form a tab of the negative electrode N. Note that the cut pieces fall onto the tray 26.

  The electrode stacking apparatus 1 includes a conveyor device 24 that conveys the cut negative electrode N to the downstream side, and an inspection camera 25 that inspects the negative electrode N on the conveyor device 24 on the downstream side of the cutter device 23. The inspection camera 25 is configured to image the negative electrode N from above and transmit data acquired by the imaging to a control device (not shown). In a control device (not shown), the imaging data is subjected to image processing, and the posture and shape of the negative electrode N, the active material peeling, and the presence / absence of a defective state such as a hole are inspected.

  The electrode laminating apparatus 1 includes a robot hand 30 that alternately stacks cells C on the conveyor device 20 and negative electrodes N on the conveyor device 24. The robot hand 30 is driven under a control device (not shown), and the robot hands 30 that have cleared the inspections in the inspection cameras 12, 14, 15, and 25 are stacked. In addition, what was judged as a defective state by the inspection in the inspection cameras 12, 14, 15, and 25 is discarded without being stacked. As a result, only defective products can be discarded before stacking, and the yield of battery cell production can be improved.

  The electrode laminating apparatus 1 repeats this superposition, and the separator S, the positive electrode P, the separator S, and the negative electrode N are set as one set, and a plurality of the sets (for example, about 100 sets) are stacked, so that the positive electrode P and An electrode laminate in which the negative electrode N and the separator S are sandwiched therebetween is formed.

  Thereafter, the tray on which the electrode stack is placed is moved to another place, and a predetermined process is performed. Specifically, the tabs of the positive electrode P and the negative electrode N are welded, respectively, and this electrode laminate is put into a laminate film made of, for example, aluminum, an electrolyte is injected, and the electrode laminate is impregnated. Thereafter, sealing and sealing are performed to obtain a laminated lithium secondary battery cell (laminated battery).

FIG. 2 is a plan view showing a stacked structure of the stacked battery according to the embodiment of the present invention. FIG. 3 is a cross-sectional configuration diagram illustrating a stacked structure of the stacked battery according to the embodiment of the present invention.
2 and 3, reference numeral P1 indicates a tab of the positive electrode P, reference numeral P2 indicates an active material (lithium-containing metal oxide) of the positive electrode P, and reference numeral P3 indicates a current collector (aluminum foil) of the positive electrode P. Moreover, the code | symbol N1 shows the tab of the negative electrode N, the code | symbol N2 shows the active material (carbon material) of the negative electrode N, and the code | symbol N3 shows the electrical power collector (copper foil) of the negative electrode N.

  As shown in FIGS. 2 and 3, the negative electrode N is larger than the positive electrode P. More specifically, the printing region (area) of the active material N2 of the negative electrode N is larger than the printing region (area) of the active material N2 of the positive electrode P.

  The size of one side of the negative electrode N (one side in the X-axis direction) is A, the size of the other side of the negative electrode N (one side in the Y-axis direction) is B, and one side of the positive electrode P (one side in the X-axis direction). Is C and the other side of the positive electrode P (one side in the Y-axis direction) is D, the size of the negative electrode N can be expressed by the following equations (1) and (2). .

A = C + 2ΔX + α (1)
B = D + 2ΔY + β (2)

  Here, ΔX and ΔY are values based on the positioning accuracy of the negative electrode N and the positive electrode P when the robot hands 30 are stacked. On the other hand, α and β are values based on the electric capacity between the negative electrode N and the positive electrode P at the end edge when the end edge of the negative electrode N is shifted from the end edge of the positive electrode P. In the present embodiment, ΔX and ΔY are doubled because the robot hand 30 is used twice during stacking.

FIG. 4 is a diagram for explaining setting of the magnitude difference based on the positioning accuracy in the embodiment of the present invention.
As shown in FIG. 4, when considering the positioning accuracy with reference to the point P which is the coordinate of one of the four corners of the positive electrode P, there are Δx and Δy as movement shifts and Δθ as rotation shifts.

  The coordinates of the point P can be represented by P (C / 2, D / 2). If the positional deviation is added to this, the coordinates of the point P ′ become P ′ (C / 2 + Δx, D / 2 + Δy). If the rotational deviation is added to this, the coordinates of the point P ′ can be expressed by the following equations (3) and (4). Equation (3) shows an equation when a rotational deviation occurs on the + side, and Equation (4) shows an equation when a rotational deviation occurs on the-side.

  As the positional deviation, on the assumption that there are Δx and Δy as the movement deviation, the maximum deviation is obtained when there is Δθ as the rotation deviation. In consideration of the fact that the maximum deviation in the X axis direction is −Δθ as the rotational deviation and the maximum deviation in the Y axis direction is the case where there is + Δθ as the rotational deviation, ΔX based on the positioning accuracy. And ΔY can be expressed by the following equations (5) and (6).

FIG. 5 is a diagram for explaining the setting of the magnitude difference based on the electric capacity in the embodiment of the present invention.
It is only the printing region (area) of the active material N2 of the negative electrode N that depends on the electrode surface dimensions in battery performance. Therefore, as shown in FIG. 5, when the edge of the negative electrode N is shifted from the edge of the positive electrode P, an electric field is generated at the edge, and the electric capacity increases accordingly.

Α and β, which are the difference in size based on the electric capacity, are expressed by the following equation, when the distance between the stacked current collector P3 of the positive electrode P and the current collector N3 of the negative electrode N is represented by L. Can do.
α = L × tan (a) (7)
β = L × tan (a) (8)
a is a value based on the electric field generated at the edge where the negative electrode N and the positive electrode P are displaced. In the present embodiment, a is set to 45 degrees, for example.

When the above formulas (5) and (7) are substituted into formula (1) and formulas (6) and (8) are substituted into formula (2), the negative electrode N to be set for the positive electrode P Is required.
In the electrode stacking apparatus 1, the positive electrode P and the negative electrode N are cut out and stacked based on the difference in size. As a result, all of the positive electrode P is covered with the negative electrode N, the battery performance is made constant, and a lithium secondary battery cell (laminated battery) with little variation in battery performance can be manufactured. Further, according to this battery, it is possible to suppress variations in battery performance of cells without using an excessive slip prevention tape in terms of battery performance, a machine for applying the tape, and a high-precision positioning device. . Further, since the size of the negative electrode N can be set to a necessary minimum source, the material of the negative electrode N is not excessively used.

  Therefore, according to the above-described embodiment, the stacked battery has a stacked structure in which the positive electrode P and the negative electrode N are alternately stacked with the separator S interposed therebetween, and the negative electrode N is larger than the positive electrode P. The difference in size between the negative electrode N and the positive electrode P is determined when the positioning accuracy of the negative electrode N and the positive electrode P when the layers are stacked and when the edge of the negative electrode N is shifted from the edge of the positive electrode P. By adopting a configuration that is set on the basis of the electric capacity between the negative electrode N and the positive electrode P at the edge, the battery performance variation can be reduced without using extra members in terms of battery performance. Can be suppressed. Further, in the present embodiment, by setting the negative electrode N having the active material N2 containing carbon whose material cost is lower than that of the positive electrode P having the active material P2 containing the lithium compound which is a rare metal, the cost of the entire battery is reduced. Increase can be suppressed.

  As mentioned above, although preferred embodiment of this invention was described referring drawings, this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

  For example, in the above embodiment, the configuration in which the negative electrode N is made larger than the positive electrode P has been described. However, in principle, the configuration in which the positive electrode P is made larger than the negative electrode N may be used.

  Further, for example, in the above-described embodiment, a lithium secondary battery is exemplified as the stacked battery, but the present invention is not limited to this configuration, and can be applied to, for example, a lithium battery, a nickel-cadmium battery, a nickel metal hydride battery, and the like. it can.

  N: negative electrode (first electrode), P: positive electrode (second electrode), N2: active material, P2: active material

Claims (3)

A laminated battery having a laminated structure in which electrodes of different polarities are alternately laminated with separators in between,
Of the electrodes, the first electrode having one polarity is larger than the second electrode having the other polarity,
The difference in size between the first electrode and the second electrode is that the positioning accuracy between the first electrode and the second electrode when the layers are stacked and the edge of the first electrode are It is set based on the electric capacity between the first electrode and the second electrode at the edge when the second electrode is displaced with respect to the edge. A feature of a stacked battery.   The stacked battery according to claim 1, wherein the first electrode is a negative electrode, and the second electrode is a positive electrode. The negative electrode has an active material containing carbon on at least one surface,
The stacked battery according to claim 2, wherein the positive electrode has an active material containing a lithium compound on at least one surface.

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