KR20020039570A - Lithium Battery Cell Having a Compromising Structure between Bobbin Type and Wound Type and Fabricating Method thereof - Google Patents

Abstract

PURPOSE: Provided is a lithium primary battery having an eclectic structure of a bobbin type and a wound type, which improves a high ratio discharge property and has a stability of the battery. CONSTITUTION: The lithium primary battery, especially lithium-thionyl chloride(Li/SOCl2) battery, is produced by a process comprising the steps of: coiling a carbon cathode plate(23) many times; coiling a separator(21) many times around the outer circumference of the coiled cathode(23); coiling a lithium foil anode plate(22) with the extended part of the separator(21) around the outer circumference of the separator(21); inserting the coiled structure of the carbon cathode plate(23), the separator(21), and the anode plate(22) into a case and then filling an electrolyte and sealing.

Description

Lithium Battery Cell Having a Compromising Structure between Bobbin Type and Wound Type and Fabricating Method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium (Li) primary battery, and in particular, the problem of capacity reduction and high-volume discharge during high rate discharge of a bobbin-type Li primary battery by changing the assembly structure of the positive and negative electrodes in the battery. The present invention relates to a lithium-thionyl chloride (Li / SOCl ₂ ) battery capable of simultaneously solving the safety problem of a secondary battery and improving both high rate discharge characteristics and ensuring battery safety at the same time.

In general, a Li primary battery is composed of three main components of an anode, a cathode, an electrolyte, a separator, and a case. Li primary battery is a battery that uses Li metal as the negative electrode of the battery. Various primary batteries are used in combination with the cathode materials MnO ₂ , SOCl ₂ , SO _2, etc., and have excellent long-term storage capability and high voltage (3- 4V) is available, and its use is expanding as a power source for emergency contact transmitters such as fire and emergency patients.

Li-based primary batteries currently produced and sold include a negative electrode as a bobbin type in which a single Li foil extruded from a Li ingot is wound and a "wound type" wound in a plurality of times. It is formed and manufactured in combination with the various anode compounds described above.

By the way, Li / MnO ₂ battery does not cause a safety problem even in the Wound structure, but Li / SOCl ₂ battery has a safety problem. This will be described in detail below.

First, in the above-described conventional bobbin type Li / SOCl ₂ battery, the anode current collector 5 is inserted into the inner circumference of the cylindrical carbon anode 3, as shown in FIGS. 1A and 1B. Wrapped with a separator (1) made of a, it forms a structure in which the lithium negative electrode (2) on the outside of the separator (1) wrapped around the separator (1) in contact with the inner wall of the case (4).

However, such a bobbin-type structure is difficult to diffuse the electrolyte solution into the deep inside of the carbon anode 3, and as a result, the anode active area is small, and thus there is a problem that the discharge capacity is significantly decreased at high rate discharge.

In addition, the conventional Wound-type Li / SOCl ₂ battery, as shown in Figures 2a and 2b is a ribbon-shaped long and thin cathode to widen the contact area of the anode 12 made of a carbon anode 13 and a lithium foil (foil) and A separator 11 made of a glassy nonwoven fabric is sandwiched between the positive electrode plates and the outside of the negative electrode 12 plates, and wound together in a cylindrical shape to be embedded in the cylindrical case 14.

However, such a wound-type structure is easy to diffuse the electrolyte to the deep inside of the carbon anode 13, and as a result, the anode active area is large, so it is suitable for high rate discharge, but instead, when the external impact is applied, the cathode 12 and the anode ( 13) Short circuits are likely to occur. In the event of such a short circuit, Li metal is an alkali metal of Group 1, which is highly reactive, and thus poses a high risk of safety accidents such as fire or explosion.

Therefore, the conventional Li / SOCl ₂ battery has a problem of capacity reduction during high rate discharge in the bobbin type, and low safety in the case of the wound type.

Accordingly, the present invention has been made in view of the problems of the prior art, and its object is to provide a bobbin type in a Li primary battery having a safety problem in a structure having a wound type such as a lithium-thionyl chloride (Li / SOCl ₂ ) battery. It is possible to secure both high capacity discharge characteristics and battery safety by simultaneously solving both the capacity reduction problem and the battery safety problem at the high rate of the bobbin type battery by the compromise type structure that takes advantage of each of the advantages of the and type. To provide a lithium primary battery that can be.

Another object of the present invention is to provide an improved bobbin-wound compromised battery that can be manufactured without additional equipment by using a pound-type manufacturing facility.

1A and 1B are partial cross-sectional perspective views illustrating an assembly structure of a conventional bobbin type Li / SOCl ₂ cell and an internal sectional view showing a winding structure of a positive electrode and a negative electrode portion;

2A and 2B are partial cross-sectional perspective views illustrating an assembly structure of a conventional Wound-type Li / SOCl ₂ cell and an internal cross-sectional view showing a winding structure of a positive electrode and a negative electrode portion;

3A and 3B are partial cross-sectional perspective views illustrating an assembly structure of a Li / SOCl ₂ battery according to the present invention, and an internal sectional view showing a winding structure of a positive electrode and a negative electrode portion;

Figure 4 is a graph showing the results of measuring the discharge capacity and high rate discharge characteristics for a conventional bobbin-type battery and a battery prepared according to the present invention.

* Explanation of Signs of Major Parts of Drawings *

21; Separator 22; cathode

23; Anode 24; case

25; Jelly roll

In order to achieve the above object, the present invention provides a case having an accommodating space therein, a plurality of coiled anodes, a cathode coiled many times on the outer periphery of the coiled anode, and the coiled anode At the same time surrounding the outer circumference and its extension is composed of a separator coiled on the outer circumference of the anode together with the cathode, and an electrolyte solution enclosed in the receiving space of the case together with the coiled anode, the cathode and the membrane structure. It provides a Li primary battery.

In the battery, the positive electrode is composed of a carbon positive electrode coated with a nickel plate on the reticulated nickel plate, and the negative electrode is preferably composed of a Li foil negative electrode that is pressed lithium metal on the reticulated nickel plate.

In addition, according to another feature of the present invention, the method for manufacturing a Li primary battery comprises the steps of coiling a carbon positive electrode alone a plurality of times, coiling a separator a plurality of times on the outer periphery of the coiled positive electrode, lithium Coiling a foil cathode plate with the extension of the separator on the outer periphery of the separator; and inserting a structure in which the cathode plate, the separator, and the cathode plate were coiled into a case, and filling and sealing an electrolyte solution. It is done.

As described above, in the present invention, the positive electrode is positioned at the center and the negative electrode is located at the outer circumference thereof, as in the bobbin type, but the positive electrode and the negative electrode each have an eclectic structure having a coil shape like a wound type.

Accordingly, the active area of the Li foil anode is improved to improve high rate discharge characteristics, and at the same time, the electrolyte may easily penetrate into the deep layer of the carbon anode by the coiling structure, thereby improving discharge capacity.

In addition, the contact area between the direct lithium foil anode and the carbon anode is not as large as a general Wound type, so the safety is excellent. Furthermore, in the mass production facility, the present invention can be produced by changing only the working conditions in the existing watt cell production line, thereby saving a separate expensive facility for bobbin cell production.

(Example)

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

3A and 3B are partial cross-sectional perspective views illustrating an assembly structure of a Li / SOCl ₂ battery according to the present invention, and an internal sectional view showing a winding structure of a positive electrode and a negative electrode.

As shown in FIG. 3B, the Li / SOCl ₂ battery according to the present invention has a positive electrode 23 having a structure coiled a plurality of times in a plate shape at an inner center like a bobbin type, and a separator 21 is surrounded on the outer circumference thereof. The outer periphery of the separator 21 has a structure in which a plate-shaped cathode 22 is wound several times together with the separator 21 and inserted into the cylindrical case 24.

In addition, as shown in FIG. 3A, the configuration of the other parts except for the positive electrode 23, the negative electrode 22, and the separator 21 is the same as that of a conventional battery.

Referring to the manufacturing process of the battery having the above-described structure, first, the carbon anode 23 compressed by a thin film on a nickel (Ni) network is first coiled a plurality of times alone, and then a separator made of a glassy nonwoven fabric ( The Separator 21 is coiled two to three times on its outer circumference.

Subsequently, the lithium foil negative electrode plate 22 pressed on the nickel mesh is coiled at least twice on the outer circumference of the carbon anode 23 that is thirdly coiled together with the separator 21 made of glassy nonwoven fabric, and then rolled into a jelly roll ( Jelly Roll) (25).

Thereafter, the lower insulating plate, the jelly roll 25, and the upper insulating plate are inserted into the cylindrical SUS case 24, and the electrolyte is filled to seal the battery. In this case, the process omitted in the manufacturing process is made in the same manner as in the prior art, so a detailed process thereof is omitted.

The battery having a new structure of the bobbin type and the wound type is improved by increasing the active area of the anode 22 made of Li foil to improve high rate discharge characteristics, and also easily penetrate electrolyte into the deep inside of the carbon anode 23. The discharge capacity can also be improved.

In addition, since the contact area between the direct lithium foil anode 22 and the carbon anode 23 is not as large as a conventional Wound type, the safety is also excellent.

Moreover, the battery of the new structure according to the present invention is similar to the bobbin type as a whole, but each part has a wound type structure, so that only the working conditions are changed in the production line of the existing wound type battery in the mass production equipment for mass production. It is possible to produce by making a separate, so that no expensive equipment investment for the production of the battery of the new structure is required.

4 shows the results of measuring the discharge capacity and the high rate discharge characteristics of the conventional bobbin-type battery and the battery manufactured according to the novel structure of the present invention.

Ⓐ: discharge capacity curve at 40mA discharge of the present invention battery

Ⓑ: discharge capacity curve at 40mA discharge of conventional bobbin battery

Ⓒ: discharge capacity curve at 250mA (high rate) discharge of the present invention battery

Ⓓ: discharge capacity curve at 250mA (high rate) discharge of conventional bobbin battery

As can be seen in Figure 4, the conventional bobbin-type battery was very severe in capacity reduction at high rate discharge. However, in the case of the improved battery of the present invention, the capacity decrease with the increase of the discharge rate is remarkably improved.

In addition, in order to determine the safety of the battery, the battery of the present invention and the conventional wound battery were tested for seven items as shown in Table 1 below, and the results are shown in Table 1.

No Test Items Quantity Test results by item The present invention Conventional example (Wound type) pass fail pass fail One Drop test 10 10 0 10 0 2 Heat shock test 10 10 0 8 2 3 Compression test 10 9 One 7 3 4 Short circuit test 10 10 0 9 One 5 Over discharge test 10 10 0 9 One 6 Filling test 10 10 0 7 3 7 Flame test 10 8 2 4 6

Note 1: If fire or explosion occurred during the test, all items were rejected.

Note 2: Dropping, short-circuit, overdischarge, and filling test items were rejected if gas leakage or electrolyte leakage occurred.

Table 2 summarizes the safety test method of Table 1.

No Test Items Test Methods Remarks One Drop test A. After 4 hours of storage at 71 ° C, drop to a level on the concrete surface at a height of 76 ± 5 cm B. Stored at -29 ℃ for 4 hours, then dropped horizontally on concrete surface at 76 ± 5㎝ height 2 Heat shock test 4 cycles of temperature at -40 ℃ for 2 hours at 70 ℃ for 1 hour 3 Compression test Fully compresses 70% dead batteries Room temperature 4 Room temperature short circuit test Weld each Ni tab to the battery terminals and connect the 0.005Ω to short the battery for 24 hours. Room temperature 5 Over discharge test A. The battery is discharged to 2.0V with 60mA of current at room temperature and then forced to discharge 500mA of forced current for 12 hours. 6 Filling test Forced charging of 500mA current for 12 hours at room temperature 7 Flame test Holds 75% discharged battery horizontally in flame and lasts until lithium ignites

As shown in Table 1, the battery of the present invention showed a high pass rate in all items, but the conventional wound battery has a high structural defect in flame test, compression test, and charging test. Appeared.

In the above embodiment, a lithium-thionyl chloride (Li / SOCl ₂ ) battery has been described as an example of a weak safety in a wound structure, but it can be applied to other types of batteries.

As described above, in the present invention, the positive electrode is positioned at the center and the negative electrode is located at the outer circumference thereof, as in the bobbin type, but the positive electrode and the negative electrode each have an eclectic structure having a coil shape like a wound type.

Therefore, the battery of the present invention improves the high rate discharge characteristics by increasing the active area of the Li foil anode as in the case of a wound type, and at the same time, the electrolyte can easily penetrate into the deep layer of the carbon anode by the coiling structure, thereby improving the discharge capacity. do. In addition, as the bobbin type, the contact area between the direct lithium foil negative electrode and the carbon positive electrode is not as large as that of the general type, which is excellent in safety.

Furthermore, in the mass production facility, the present invention can be produced by changing only the working conditions in the existing watt cell production line, so that it is possible to save a separate expensive equipment purchase cost for the bobbin cell production.

In the above, the present invention has been illustrated and described with reference to specific preferred embodiments, but the present invention is not limited to the above-described embodiments and is not limited to the spirit of the present invention. Various changes and modifications can be made by those who have

Claims (5)

A case having an accommodation space therein, Anode coiled multiple times, A cathode coiled multiple times on an outer circumference of the coiled anode, A separator which surrounds the outer circumference of the coiled anode and at the same time an extension thereof is coiled on the outer circumference of the anode together with the cathode; Li primary battery, characterized in that consisting of an electrolyte solution encapsulated in the accommodating space of the case together with the coiled cathode, anode and separator structure. The lithium primary battery according to claim 1, wherein the positive electrode comprises a carbon positive electrode that is press-coated on the reticulated nickel plate, and the negative electrode is formed of a Li foil negative electrode that compresses lithium metal onto the reticulated nickel plate. . The Li primary battery according to claim 1 or 2, wherein the Li primary battery is a lithium-thionyl chloride (Li / SOCl ₂ ) battery. Coiling the carbon bipolar plate alone multiple times, Coiling the separator a plurality of times on the outer circumference of the coiled anode; Coiling a lithium foil negative plate together with an extension of the separator to an outer circumference of the separator; And inserting a structure in which the positive electrode plate, the separator, and the negative electrode plate are coiled into a case, filling the electrolyte, and sealing the electrolyte. The method of claim 4, wherein the Li primary battery is a lithium-thionyl chloride (Li / SOCl ₂ ) battery.