JP2006031940A - Coin-shaped battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coin-shaped battery whereby current collection between a positive electrode and a positive electrode can be stably obtained, and increase of internal resistance and deterioration of a closed circuit voltage based on swelling of the battery are seldom caused. <P>SOLUTION: In this coin-shaped battery formed by housing power generating elements including the positive electrode, a negative electrode, and an electrolyte in a space formed by the positive electrode, an negative electrode terminal plate, and a ring gasket, a ribbon-shaped collector formed by twisting its both ends in the mutually opposite directions is interposed between the bottom surface of the positive electrode and the inner bottom surface of the positive electrode can. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a coin-type battery, and more particularly to a coin-type battery in which current collection between a positive electrode and a positive electrode can is stably obtained.

  Recently, a battery that can be used as a power source of equipment used in a high temperature atmosphere exceeding 100 ° C. such as a pressure sensor inside a tire has been required. For such applications, a coin-type battery typified by a coin-type lithium battery has been studied as a promising candidate battery.

  Such a coin-type battery employs a structure in which a power generation element including a positive electrode, a negative electrode, and an electrolytic solution is accommodated in a space formed by a positive electrode can, a negative electrode terminal plate, and an annular gasket. When the battery is used, the battery swells due to the generation of gas or the expansion of the electrolyte, and therefore, particularly in a state where the discharge has progressed, it becomes difficult to collect the current of the positive electrode and the positive electrode can, and the internal resistance of the battery increases. There was a problem that the closed circuit voltage decreased.

  Therefore, as shown in FIG. 3, a current collector 7 in which both ends 7 a and 7 b are bent slightly upward is interposed between the bottom surface of the positive electrode and the inner bottom surface of the positive electrode can. It has been proposed to make it easier to collect current between the two (for example, Patent Document 1).

Although the current collector required has been obtained through the current collector as described above, if it is required to be used at a higher temperature in the future, There is a problem that current collection between the positive electrode and the positive electrode can cannot be sufficiently obtained, and the above-described demand cannot be sufficiently met.
Japanese Patent Laid-Open No. 61-133571

  An object of the present invention is to provide a coin-type battery in which current collection between a positive electrode and a positive electrode can is stably obtained even in use in a high-temperature atmosphere in view of the circumstances of the coin-type battery as described above. To do.

  The present invention relates to a coin-type battery in which a power generation element including a positive electrode, a negative electrode, and an electrolyte is accommodated in a space formed by a positive electrode can, a negative electrode terminal plate, and an annular gasket. In the meantime, the above-mentioned problem is solved by interposing a ribbon-shaped current collector in which both ends are twisted in opposite directions (that is, both ends are opposite to each other).

  ADVANTAGE OF THE INVENTION According to this invention, the coin-type battery from which the current collection between a positive electrode and a positive electrode can is obtained stably can be provided.

  In other words, the current collector that has been bent at both ends slightly upwards does not necessarily have sufficient restoring force, so that the battery is swollen when used or stored at high temperatures. In such a case, the force to restore the current shape of the current collector cannot follow the swelling of the battery, so that sufficient current collection cannot be obtained between the positive electrode and the positive electrode can. Since the current collector is twisted at opposite ends (opposite directions), the current collector is less likely to lose its restoring force, so that in the present invention, the battery is used in a high temperature atmosphere. Even when swelling occurs, the current collector follows it and restores its original shape, and current collection between the positive electrode and the positive electrode can is stably obtained. As a result, in the coin type battery of the present invention, even when used in a high temperature atmosphere of about 150 ° C., an increase in internal resistance and a decrease in closed circuit voltage due to a decrease in current collection between the positive electrode and the positive electrode can are suppressed. Is done.

  Next, an embodiment of a coin-type battery and a current collector used therefor will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view schematically showing an embodiment of a coin-type battery of the present invention, FIG. 2 is a view schematically showing an embodiment of a current collector used in the present invention, and FIG. In the front view, (b) is a plan view thereof.

  First, FIG. 1 clarifies where the current collector used in the present invention is arranged in the battery. The coin battery includes a positive electrode 1, a negative electrode 2, a separator 3, a positive electrode can 4, a negative electrode terminal plate 5, an annular gasket 6, and a current collector 7.

  The positive electrode 1 is accommodated in a positive electrode can 4, and the current collector 7 is interposed between the bottom surface of the positive electrode 1 and the inner bottom surface of the positive electrode can 4.

  As shown in FIG. 2, the current collector 7 has both ends 7a and 7b twisted in opposite directions, that is, the end 7a and the end 7b are twisted in opposite directions. Although it is pressed by the pressing force from above through the positive electrode 1, it is shown in a flat plate shape. However, if the battery swells due to gas generation inside or evaporation of the electrolyte solvent, the swell is generated. Depending on the degree of current collection, the current collector 7 continues to contact the positive electrode 1 and the positive electrode can 4 in an attempt to restore the original shape shown in FIG. As a result, even when used at a high temperature, the current collection between the positive electrode 1 and the positive electrode can 4 can be stably obtained as compared with the conventional battery.

  The negative electrode 2 is accommodated on the negative electrode terminal plate 5 side, a separator 3 is interposed between the negative electrode 2 and the positive electrode 1, and an electrolytic solution (not shown) is mainly impregnated in the separator 3.

  The power generation element such as the positive electrode 1, the negative electrode 2, the separator 3, and the electrolyte and the specific current collector are accommodated in a space formed by the positive electrode can 4, the negative electrode terminal plate 5, and the annular gasket 6, The inside of the battery is sealed so as to have a hermetically sealed structure. The sealing is performed by tightening the opening end portion of the positive electrode 1 inwardly so that the annular gasket 6 is opened around the peripheral folded portion of the negative electrode terminal plate 5 and the positive electrode can. This is performed by being brought into pressure contact with the inner peripheral surface of the end portion.

  In the present invention, the current collector 7 has a ribbon shape, and the ribbon shape may be referred to as a substantially strip shape or an elongated plate shape, and the material thereof is not particularly limited, and various types are used. For example, those made of stainless steel (SUS430, SUS444, SUS316, etc.) are preferably used.

  In the present invention, it is preferable to twist the both ends 7a and 7b of the current collector 7 in such a range that one side surface in the length direction does not reach the center portion in the width direction. That is, when the battery is assembled, it is preferable that the twisted portion is arranged in a flat plate shape without being folded over on the untwisted portion.

  The present invention is characterized in that the current collector 7 having the ends 7a and 7b twisted in the opposite direction as described above is interposed between the bottom surface of the positive electrode 1 and the inner bottom surface of the positive electrode can 4. With respect to the other configuration, a configuration conventionally employed for a coin-type battery can be employed. That is, with respect to the positive electrode 1, the negative electrode 2, the electrolyte solution, the separator 3, the positive electrode can 4, the negative electrode terminal plate 5, the annular gasket 6, etc., a conventionally employed configuration can be adopted. Needless to say, it is possible to appropriately change and adopt a conventionally used configuration.

  In the battery industry, a flat battery having a diameter larger than the height is called a coin-type battery or a button-type battery, but there is a clear difference between the coin-type battery and the button-type battery. However, the coin type battery of the present invention does not exclude what is called a button type battery, and such a battery called a button type battery is also included in the scope of the coin type battery of the present invention.

  Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the examples illustrated in the examples.

Example 1
In producing the coin-type battery of Example 1, the current collector 7, the positive electrode 1, the negative electrode 2, the separator 3, the electrolyte, the positive electrode can 4, the negative electrode terminal plate 5, and the annular gasket 6 were used as follows. . First, the current collector 7 is made of SUS430 having a thickness of 0.1 mm, the dimensions before twisting are 20 mm × 7 mm in length × width, and are in a ribbon shape, as shown in FIG. What twisted the both ends 7a and 7b to the opposite direction was used. As for the twists at both ends 7a and 7b of the current collector 7, portions up to 5 mm from both ends are twisted, and the degree of twist is twisted at an angle of 45 ° with respect to the horizontal plane.

  In the production of the positive electrode 1, manganese dioxide is used as a positive electrode active material, artificial graphite is used as a conductive auxiliary agent, polytetrafluoroethylene is used as a binder, and they are mixed to produce 91.7% by mass of manganese dioxide. A positive electrode mixture was prepared so that graphite was 7.6% by mass and polytetrafluoroethylene was 0.7% by mass. Then, the positive electrode mixture was filled in a mold and pressure-molded to produce the positive electrode 1. This positive electrode 1 had a diameter of 20 mm and a thickness of 3.0 mm.

  The positive electrode can 4 is made of stainless steel and has a bottomed cylindrical shape with nickel plating on the surface. The negative electrode terminal plate 5 is formed of a stainless steel plate having a peripheral folded portion, and the surface thereof is nickel plated. The thing which gave is used.

As an electrolytic solution, an organic electrolytic solution prepared by dissolving 0.5 mol / l of LiClO _{4 in} a mixed solvent of propylene carbonate and 1,2-dimethoxyethane in a volume ratio of 1: 1 was used.

  The negative electrode 2 is obtained by stacking a lithium plate having a diameter of 19 mm and a thickness of 1.0 mm and a thin aluminum foil having a diameter of 19 mm and punching it into a predetermined size in the negative electrode terminal plate 5. A lithium-aluminum alloy electrochemically alloyed with was constructed.

  The separator 3 is made of polypropylene nonwoven fabric, and the annular gasket 6 is made of polypropylene, and is used together with the positive electrode 1, positive electrode can 4, negative electrode terminal plate 5, electrolyte, current collector 7, and the like. A coin-type battery having a diameter of 24.5 mm and a height of 4.90 mm with the structure shown in FIG. 1 was produced.

Comparative Example 1
The current collector is made of SUS430 with a thickness of 0.1 mm and has the same ribbon shape as in Example 1, and its both end portions 7a and 7b are bent slightly upward as shown in FIG. A coin-type battery is manufactured in the same manner as in Example 1, except that each end is about 2 mm above the horizontal plane and this current collector is interposed between the bottom surface of the positive electrode and the inner bottom surface of the positive electrode can. did.

  The batteries of Example 1 and Comparative Example 1 were stored in an atmosphere of 120 ° C. and 0% relative humidity, and the internal resistance and closed circuit voltage were measured during the storage. The internal resistance was measured at an alternating current of 1 kHz, and the closed circuit voltage was measured by discharging at 100Ω for 5 seconds. The results are shown in FIG. 4 and FIG.

  As shown in FIG. 4, the battery of Example 1 has a smaller increase in internal resistance due to the increase in storage time than the battery of Comparative Example 1, and the battery of Example 1 as shown in FIG. Compared with the battery of Comparative Example 1, there was little decrease in the closed circuit voltage accompanying an increase in storage time.

  As described above, the battery of Example 1 had less increase in internal resistance and less decrease in the closed circuit voltage than the battery of Comparative Example 1. The battery of Example 1 was the battery of Comparative Example 1. This is because the current collection between the positive electrode and the positive electrode can is stably obtained even at a high temperature. On the other hand, the battery of Comparative Example 1 is considered to have increased internal resistance and decreased closed circuit voltage because current collection between the positive electrode and the positive electrode can deteriorate at high temperatures.

  In the above embodiment, the coin-shaped battery having a circular planar shape has been described. However, the present invention is not limited to this, and can be applied to a coin-shaped battery having a square planar shape.

It is sectional drawing which shows roughly one Embodiment of the coin-type battery of this invention. BRIEF DESCRIPTION OF THE DRAWINGS One Embodiment of the electrical power collector used for the coin-type battery of this invention is shown roughly, (a) is the front view, (b) is the top view. The current collector used for the conventional coin type battery is shown roughly, (a) is the front view, and (b) is the top view. It is a figure which shows the change of internal resistance in the battery of Example 1 and the battery of the comparative example 1 during high temperature storage. It is a figure which shows the change of the closed circuit voltage during the high temperature storage of the battery of Example 1 and the battery of Comparative Example 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Separator 4 Positive electrode can 5 Negative electrode terminal plate 6 Annular gasket 7 Current collector 7a Current collector end 7b Current collector end

Claims (1)

A coin-type battery in which a power generation element including a positive electrode, a negative electrode, and an electrolytic solution is accommodated in a space formed by a positive electrode can, a negative electrode terminal plate, and an annular gasket, the bottom surface of the positive electrode and the inner bottom surface of the positive electrode can A coin-type battery characterized in that a ribbon-shaped current collector in which both ends are twisted in opposite directions is interposed between the two.

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