JPS60241640A - Cell - Google Patents

Abstract

PURPOSE:To improve liquidtightness by forming the positive electrode can of a button-type cell or the like with a shape memory alloy, doing works upon it in a finished shape at a temperature above its transformation point, assembling it at a temperature below its transformation point and thereafter bringing it back to the finished shape. CONSTITUTION:A button-type silver oxide cell or the like is formed by forming its positive electrode can with a shape memory alloy and combining it with positive electrode black mix 1, a separator 3, negative electrode black mix 2, a negative electrode can 5 and packing 6. At this time, a Ti-Ni alloy or the like forming the positive electrode can 4 is worked in a finished shape having a bent part in a mother state above the martensite transformation point and then after the bent part is straightened in the stable martensite phase below -20 deg.C, each part is inserted and thereafter it is brought back to the room temperature, accordingly into the mother phase state and sealed by tightening the packing 6. Therefore, it is possible to obtain appropriate packing pressure without spring back and thereby to improve its liquidtightness.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a material for a battery can, which is a battery case, and a cathode lid.

BACKGROUND ART In recent years, the number of electronic devices using batteries has increased rapidly, and the use of IC circuits and low power due to high efficiency has resulted in a significant increase in battery life. This is especially noticeable in Vr-watches and calculators, and popular types of analog (pointer type) watches typically have a lifespan of 5 years.Digital watches also have a lifespan of 3 to 5 years, and lithium Some batteries can last up to 7 years.Furthermore, solar-powered watches that convert solar energy into electricity and aim to provide a permanent power source are said to last for 7 to 10 years or more.Battery life also benefits the user. , and it tends to increase every year.

However, the problem here is the service life of the battery itself, that is, leakage. In general, lithium batteries are said to have good leakage resistance, but they have disadvantages such as being difficult to draw a large current of 10 mA and being large in size.On the other hand, mercury batteries and silver batteries are Poor leakage resistance, 5
It only has a leak resistance of ~6 years.

The purpose of the present invention is to improve the leakage resistance of the above-mentioned battery, and to provide a wristwatch or an electronic device that has a long life and reliability and is beneficial to many users. be.

FIG. 1 shows a typical cross section of a button-type silver oxide battery as a representative battery. The anode 1 is made of silver oxide (A'), which is a depolarizer.
The cathode 2 is a pellet made by mixing and press-molding carbon powder as a conductive agent with carbon powder as a conductive agent, and the cathode 2 is amalgamated (Htl 0
It consists of zinc powder of around 50% and gelled electrolyte. The comb layer 3 is composed of three layers: a retention film, a separator, and a protective film in order from the top, and the retention film keeps stains from cotton and nylon from being dissolved. The separator is similar to a cellulose-based several-layer separator.9 It allows ions of the electrolyte to freely pass between the anode 1 and the cathode 2, and also has the role of physically separating the separator. When it comes into contact with silver, it oxidizes and becomes easily damaged, so the separator is protected. The case consists of a battery can 4, a cathode lid 5, and a packing 6, each of which serves to prevent liquid leakage, to collect current at both electrodes, and to obtain stable contact with the contacts. Electric power can be generated by the chemical reaction between the anode 1 and the cathode 2.

The manufacturing method of such a battery is to form a battery can 4 into a cylindrical shape as shown in FIG.
The positive 41, the separator filter, the gasket 6, the cathode 2, and the cathode lid 5 are placed in this order, and the cathode lid 5 is pressed from above with an insulating member, and the upper outer periphery of the battery can 4 is press-molded inward. It is completed by bending it like this. In this conventional method, an anode, a separator, and @
Pole, / (After inserting the cover, the final step is press forming to complete the product, so it is not possible to bend the outer periphery of the upper part of the battery can sufficiently.

If sufficient bending is performed, each internal member will be damaged and the product will be defective. Also, even if the battery can is bent to the point of breakage, the material of the battery can will spring puncture and will return to its original shape. Therefore, due to insufficient bending and springback, insufficient contact pressure between the packing and the battery can, and the packing and the cathode cover cannot be maintained, resulting in leakage due to alkaline electrolyte creeping up and generation of hydrogen gas due to chemical changes. There were problems such as leakage due to increased internal pressure. When liquid leaks, it corrodes and damages the contacts, causing contact failure, damaging related parts, and carbonates generated from leaking liquid that are released and cause the clock to stop.

To improve leakage resistance, make the volume of the gasket sufficiently large, press-form the top of the battery can, and tighten it thoroughly when sealing.
It is possible to make it much better than a trap by configuring it so that the contact pressure is large, or by making the contact length between the battery can and the cathode lid sufficiently long. If this is carried out, the volume occupied by the anode, tooth electrode, and separator members will be small, fL, b, and therefore the capacity will be greatly reduced, the battery life will be shortened, and the user will be inconvenienced, which is undesirable.

This invention is intended to eliminate the drawbacks of the present invention and will be described in detail below.

First, let's talk about the characteristics of shape memory alloys.

Metals and alloys are made up of crystals in which atoms are regularly arranged. When this phase transformation occurs while it remains in a solid state, the crystal structure changes. One type of this phase transformation is called martensitic transformation.

In this type of transformation, the phase that has a stable structure at a higher temperature than the temperature called the transformation point is called the parent phase, and the phase that has a stable structure at a lower temperature is called the parent phase. This is called the martensitic phase.

When the temperature is gradually cooled from the high temperature side, transformation from the parent phase to the martensitic phase occurs (referred to as martensitic transformation).
Conversely, when heated, the martensitic phase transforms into the parent phase (referred to as reverse transformation).

Martensitic transformation is a process in which the matrix undergoes uniform strain along a plane with a square atomic arrangement, as shown in part A at the bottom of Figure 4, and is transformed into a parallelogram, as shown in part B. If the atoms become aligned, this is martensitic transformation.

Each atom does not move independently, but changes while maintaining mutual cooperation, and is in a fixed relationship with the original atomic position.

Furthermore, martensitic transformation itself is a type of deformation mechanism.

Such martensite can be formed not only in one way, but also by displacing atoms in the opposite direction, as shown in part 0 in FIG. 4, for example. Both B and O parts have the same crystal structure, or have different crystal orientations. Therefore, this is called martensite's older brother, crystal. In actual metal crystals, up to 24 types of older crystals are known.

Now, when the alloy in the matrix state is cooled below the transformation point, a martensitic transformation of 1m occurs, but in order to minimize the strain energy, several older crystals are grouped together and as a whole, as shown in Figure 6, the martensite transformation occurs. It undergoes a metamorphosis whose shape is almost the same as in Figure 5. (Here, for ease of explanation, only the two sets of older crystals are illustrated.) The sample in the martensitic state is 1c7 above the transformation point.
Naturally, reverse transformation occurs when heated to 111°C, but at that time, both older crystals try to return to their original crystalline state, including not only their structure but also their orientation, so they return to the original state shown in Figure 5.

When stress is applied to the sample in the martensitic state shown in FIG. 6 and the sample is deformed, the interface between the older crystals moves and one of them eats the other older crystal and grows, resulting in the state shown in FIG. 7. When heated above the transformation point, each older crystal returns to its original matrix state as shown in FIG. This is the essence of the shape memory effect. This shape memory effect has two important characteristics.

First, only the shape of the matrix phase is stored, and the shape of the martensitic phase is not normally stored. Second
This phenomenon occurs even under high external stress. There are currently many shape memory alloys, including copper-aluminum-nickel (aluminum-bronze), titanium-nickel, copper-zinc, copper-zinc-aluminum, silver-cadmium, and copper-tin.

Here, the case where the martensitic transformation point is -15 to -20°C will be explained as an example. A Ti--IJi alloy is processed into a cross-sectional shape as shown in FIG. 8 in a state where the matrix is at a temperature higher than the martensitic transformation point to form a battery can 7.

The upper part of the battery can 7 is bent inward, and this bending is the same shape as when the battery is assembled and completed as shown in Figure 1, or even more so that it makes good contact with the gasket. It is processed into a shape.

Next, it is processed into a straight cylindrical shape similar to the shape explained in FIG. 2 in a stable martensitic phase at -20°C or lower. In this state, put the anode 1, separator 5, gasket 6, anode 2, and cathode cover 5 into the battery can 7 in the same manner as shown in Fig. 5, and press the ugly electrode cover 5 from above with an insulating material with appropriate pressure and keep it in place. I gag. Then, the 71p battery can 7 in the matrix returns to its original shape, resulting in the state shown in Figure 1. In the state shown in FIG. 8, sufficient processing has been performed to ensure sufficient contact pressure and contact length between the battery can and the packing, and between the packing and the cathode cover, improving leakage resistance. Additionally, the volume of the gasket can be reduced by reducing the bending of the battery can, and the anode,
By increasing the volume of the anode, a higher capacity can be obtained with the same size battery, and the life of the wristwatch can be extended. Because positive, lt1, and other materials are incorporated at low temperatures, fewer chemical reactions are required. Fig. 9 shows an example in which a shape memory alloy is used for the cathode cover, and the outer periphery of the cathode cover 8 is a matrix with a folded part opened outward compared to the state in which the battery in Fig. 1 is completed and assembled. It is formed into a martensitic phase at −20° C. or lower, and is processed into the same shape as the completed VC81 shown in FIG. 10, as shown in FIG. Assemble this at a low temperature of -20 DEG C. or lower as shown in FIG. 3, press the battery can, and leave it at room temperature.Then, the electrode cover 8 will spread to apply pressure to the gasket, and sufficient contact pressure will be obtained. FIG. 11 shows another embodiment of this cathode lid 8, in which the outer peripheral portion of the matrix is open outward, and at the same time, the outermost collar portion 9 is also open outward. −
A similar effect can be obtained by processing and incorporating the martensitic phase into the shape shown in FIG. 10 at 20° C. or lower.

Furthermore, by making both the battery can and the cathode lid from a shape memory alloy, a more stable and high contact pressure can be obtained and a battery with good leakage resistance can be obtained.

According to the present invention, in a button type battery which maintains airtightness by sandwiching a gasket between the bent portion of the upper end of the cylindrical anode battery can and the outer circumferential folded portion of the cathode lid, one or both of the anode battery can and the cathode lid are provided. is made of a shape memory alloy, the bending part is made to have an inclination greater than the assembled state at gA degrees above the transformation point, and the folded part is widened, and the inclination is returned to the original state at mviL below the transformation point. Taking advantage of the properties of shape memory alloys, by returning the temperature to above the transformation point again,
By tilting the bent part of the anode battery can or by widening the folded part of the anode lid, the gasket is pressed and an airtight seal is maintained, so it has the following effects.

a) Conventionally, button-type batteries were hermetically sealed by pressing the gasket by bending the upper open end of the anode battery can with a press. However, since bending by press working always involves springback, if the bending head is made larger in order to ensure airtight sealing, an excessive 710 pressure will be applied to the electrode material and the separator 1-, which may cause damage.

Furthermore, if the amount of bending is reduced for fear of breakage, there is a problem in that a reliable airtight seal cannot be maintained. In order to solve this problem, there was also a configuration in which the contact length of the battery was increased, but this required sacrificing the internal capacity, making it difficult to apply to small button batteries.

On the other hand, the present invention makes use of the properties of shape memory alloys to obtain an appropriate pressure force on the packing without springback, and it is possible to achieve reliable airtight sealing without any damage to the battery filling, and the packing Since there is no need to increase the contact length, a compact, large-capacity button battery can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a typical cross section of a button-type silver oxide battery. FIG. 2 is a cross-sectional view of the battery can during processing. FIG. 3 is a sectional view of the battery during assembly. FIG. 4 is a diagram showing the atomic arrangement of a shape memory alloy. FIG. 5 is a diagram showing the state of the matrix of the shape memory alloy. FIG. 6 is a diagram showing the state of the martensitic phase of the shape memory alloy. FIG. 7 is a diagram showing the sample in FIG. 6 in a deformed state. FIG. 8 is a sectional view of the battery can in the middle of the battery can according to the present invention. Figure 9 is a cross-sectional view of the cathode lid during processing according to the present invention. FIG. 10 is a sectional view with the cathode cover of FIG. 9 added. FIG. 11 is a cross-sectional view showing another embodiment of the cathode cover according to the present invention during processing. 1...Anode 2...Cathode 5...Separator layer 4.7...Battery can 5.8...Tooth electrode cover 6...Packing? , 0. Soba Department and above Applicant Suwa Seikosha Co., Ltd. Agent Masuji Mogami Tsutomu TFL Tetsu '11 Garden Law / River

Claims (1)

[Claims] +11 An anode agent, a separator layer, a packing, and a cathode lid are sequentially laminated from the bottom of a cylindrical anode battery can, and the cathode agent is disposed between the separate layer and the cathode lid, and The anode battery can has a bent portion in which the upper end opening is inclined inward;
The cathode lid has a folded part extending parallel to the battery can on its outer periphery, and the bent part is configured to press the packing with the folded part to maintain airtightness, and the anode battery can is made of shape memory alloy. At the same time, it is assembled at a temperature above the transformation point to form a bent part with an inclination greater than the shape, and the said inclination is returned at a temperature below the transformation point, and after assembly, the bending part is made to have an angle above the transformation point. A battery characterized in that the packing is pressed by the bent portion. (2) An anode agent, a separator layer, packing, and a cathode lid are sequentially laminated from the bottom of a cylindrical anode battery can, and the cathode agent is disposed between the separate layer and the anode lid, and the anode battery can has a bent part where the upper end opening is inclined inward,
The cathode lid has a folded part extending parallel to the battery can on the outer periphery, and the bent part is configured to press the packing with the folded part to maintain airtightness, and the cathode lid is made of a shape memory alloy. At the same time, the folded portion is formed into a shape that expands outward at a temperature higher than the transformation point, the expansion is returned to the outside at a temperature lower than the transformation point, and the temperature is raised to the transformation point or higher after assembly. A battery characterized by being formed by pressing the gasket. (3) From the bottom of the cylindrical anode can, remove the anode agent,
A gasket and a cathode lid are sequentially laminated, and a cathode agent is disposed between the separate layer and the cathode lid, and the anode battery can has an upper opening or an inwardly bent part, and the cathode lid has a folded part extending parallel to the battery can on the outer periphery, and is configured such that the bent part presses the packing with the folded part to maintain airtightness, and the anode battery can and the cathode lid are made of shaped alloy. At a temperature equal to or higher than the transformation point, the anode battery can is formed such that the bent portion has an inclination of more than a square shape when assembled, and the cathode lid is formed such that the folded portion is expanded outward. The inclination of the bent part and the spread of the folded part are returned to m degrees below the transformation point, and the packing is pressed by the bent part and the folded part by mtVc above the transformation point after assembly. A battery that has a very small capacity.