JPH04167375A - Rectangular lithium secondary cell - Google Patents

Abstract

PURPOSE:To make it possible to easily assemble and fabricate a rectangular lithium cell by folding one electrode plate zigzag, and disposing the other electrode in it via a separator to form a group of electrode plates. CONSTITUTION:A strip positive electrode plate 1 having a rechargerable active material 1b applied to metallic foil 1a is folded zigzag or wound and a negative electrode 2 is disposed in the folded portion of the positive electrode plate 1 via a separator 3 to form a group of electrode plates. The group of electrode plates are stored in a rectangular container and a highly economical lithium secondary cell is offered which can be easily assembled and fabricated. The same product can also be made by forming into a negative electrode out of a folded band electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to prismatic lithium secondary batteries, and particularly to improvements in electrode structure.

[Conventional technology] Lithium batteries have high energy density, high voltage, and excellent long-term storage properties, and are widely used as memory backup power sources for various battery devices and power sources for communication devices. Batteries are required. Among these, prismatic lithium secondary batteries have good volumetric efficiency when installed in equipment, leading to smaller and lighter equipment.

Currently, prismatic lithium secondary batteries have not been developed, but their structure may be similar to prismatic nicato batteries or sealed batteries.

For example, the ``prismatic sealed nickel cadmium battery'' published in Battery Technology (1989 first issue) published by the Battery Technology Committee of the Electrochemical Society, and r high capacity technology and flat prismatic Ni
-The battery structure described in ``Development of Cd batteries'' is given as an example.

The cross-sectional configuration diagram in FIG. 9 shows the structure of a conventional square bicadmium battery. The active material (12) is coated or impregnated on the current collector (11) serving as a base material, and a part of the exposed current collector (13) (1'l) is electrically connected to the lead terminals (15) (16). They are collectively connected to a battery case (18) which also serves as a positive terminal (17) or a negative terminal.

Next, a case of a prismatic lithium secondary battery having a structure similar to the above-mentioned Nikato battery will be described.

Fig. 10 is a schematic plan view showing the structure of the positive electrode plate, Fig. 11 is a schematic plan view showing the structure of the negative electrode plate, and Fig. 12 is a conventional method in which the positive and negative electrode plates are housed in a square battery case. FIG. 2 is a cross-sectional configuration diagram showing the internal structure of a prismatic lithium secondary battery.

The positive electrode plate (21) has a base material (22) coated with a rechargeable active material (23), and an ear part (24) for collecting current is provided on the top of the base material (22). . Base material (22)
Materials include mesh, expanded metal, punched metal, etc., such as stainless steel, titanium, and aluminum. On the other hand, the negative electrode plate (31) is made of lithium metal, lithium alloy, etc., and is provided with an ear (32) at the top for collecting current. An electrode plate group in which a plurality of positive electrode plates (21) and negative electrode plates (31) are laminated with a separator (3) in between is housed in a battery case (4) to form a square lithium secondary battery. In addition, the ears (24) of each positive electrode plate (21)
are assembled, connected to the lead terminal (25), and connected to the positive electrode terminal (26), and the negative electrode plate (31) is similarly assembled with its respective ears (32) and connected to the lead terminal (3).
3) and is connected to a battery case (4) which also serves as a negative terminal.

[Problems to be Solved by the Invention] However, in lithium secondary batteries, it is necessary to increase the battery area in order to improve charging and discharging efficiency. Therefore, the number of electrode plates required is about 2 to IO times that of a nicato battery. In order to produce a lithium secondary battery, there are several steps: cutting the electrode plates to a certain size, providing ears for current collection on each plate, stacking them with high precision through separators, and laminating the plates. After that, the above-mentioned process of collectively connecting the tabs of the electrode plates, etc. must be carried out, which poses the problem of being complicated and unsatisfactory as a manufacturing method for a lithium secondary battery that requires a large number of electrode plates.

This invention was made to solve the above-mentioned problems, and aims to provide a prismatic lithium secondary battery that can be easily assembled and manufactured, and that can reduce manufacturing costs.

[Means for Solving the Problems] The prismatic lithium secondary battery of the present invention has a positive electrode plate (or a negative electrode plate mainly composed of lithium) having a continuous band-shaped rechargeable active material folded in a zigzag shape, or winding;
The above-mentioned negative electrode plates (or positive electrode plates) are disposed between them with separators interposed therebetween to form an electrode plate group, which is housed in a rectangular container.

[Operation] In this invention, for example, by using a flexible continuous strip-shaped positive electrode plate having an active material coated on a metal foil, a zigzag pattern is formed between the positive electrode plate and the negative electrode plate through a separator. The positive electrode plate and the negative electrode plate can be easily aligned by, for example, being folded into a shape, and the negative electrode plate is brought into contact with the folded portion via a separator. In addition, the current collector REET' terminal of the positive electrode plate only needs to be provided at one location, which greatly simplifies the manufacturing process.

[Example code] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional configuration diagram showing the configuration of an electrode plate group according to an embodiment of the present invention, and FIG. 2 (aXb) shows the structure of the positive electrode plate in FIG. 1, where (a> is a front view, (b) is a side view, FIG. 3 (aXb) shows the structure of the negative electrode plate equipped with a separator, (a) is a front view, (b) is a side view, and FIG. 1 is a cross-sectional configuration diagram showing a square lithium secondary battery according to an embodiment of the present invention, in which the electrode plate group shown in the figure is housed in a square container.

In this example, a continuous strip-like monolithic cathode plate (1) coated with a rechargeable active material (lb) on a metal foil (la) is folded in a zigzag pattern, and between adjacent cathode plates A negative electrode plate (2) is arranged through a separator (3) to form an electrode plate group, and a lead terminal (LC) for extracting current is attached to the end of the positive electrode plate (1). .

The positive electrode plate (1) has a structure in which a rechargeable active material (lb) is coated on a continuous metal foil (la), and the rechargeable active material (lb) is, for example, lithium. Composite MnO2+ V2O5, Ti52. Examples include metal oxides such as MO52 and conductive polymers such as polyaniline and polypyrrole. The metal foil (la) may be made of a corrosion-resistant and conductive material, for example, titanium, stainless steel, aluminum, etc. are suitable. The method of applying the rechargeable active material (lb) onto the metal foil (la) is to use a screen printing method, a coater method using a doctor blade, etc. by slurrying the active material mixture with a conductive agent, a binder, a solvent, etc. etc., and can be easily manufactured. A glue terminal for extracting current is connected to a part of the metal foil (la).

The negative electrode plate (2) is rechargeable and made of lithium metal, lithium aluminum alloy, or alloy of lithium and other elements, and is provided with an ear (2a) at the top for extracting current. This negative electrode plate (2) is separated by a separator (3) so as not to come into contact with the positive electrode plate (1). The separator (3) has a bag shape or is formed by welding three or four sides by heat fusion or the like, and is made of a microporous film such as polypropylene or polyethylene, or a nonwoven fabric.

The electrode plate group shown in Fig. 1 is housed in a rectangular battery storage case (4), which is a rectangular container, as shown in Fig. 4, and the lead terminal (1c) is connected to the positive terminal (4a). , negative electrode plate (
The ears (2a) of 2) are assembled and connected to the inside of a battery storage case (4) which also serves as a negative electrode terminal to produce a square lithium secondary battery. Although not shown, the lead terminal (1c) is protected with an insulating film to prevent it from coming into contact with the battery storage case (4).

FIG. 5 is a cross-sectional configuration diagram showing another example of the electrode plate group according to the present invention, which has almost the same structure as the electrode plate group shown in FIG. 1, but with the bent portion of the positive electrode plate (1) No active material (lb) is applied to the metal foil. The positive electrode plate (1
) is shown in the front view of FIG. 6(a) and the side view of FIG. 6(b). In this positive electrode plate (1), an uncoated part (ld) of the active material (1b) is formed in advance at a place corresponding to the bending part when assembling the electrode plate group, and this part is coated with metal foil (la).
is exposed. The electrode plate group shown in FIG. 5 is housed in the rectangular battery storage case (4) shown in FIG. 4 as in the above embodiment, and the lead terminal (IC) is connected to the positive terminal (4a). The ears (2a) of the negative electrode plate (2) are assembled and connected to the inside of a battery storage case (4) which also serves as a negative electrode terminal to produce a square lithium secondary battery.

In the battery configured as described above, one battery is made up of two continuous strip-shaped positive electrode plates, so no complicated work is required in the process of manufacturing the positive electrode plate. In particular, since there is only one lead terminal, the work of connecting the positive electrode terminal is greatly simplified. In addition, in the assembly process of the electrode plate group, a separator is attached to the negative electrode plate in advance, so that two types of parts, the positive electrode plate and the negative electrode plate, are assembled, and the process of folding the positive electrode plate is facilitated. Roughly speaking, if the positions of the positive and negative electrode plates are misaligned, the battery life will be significantly shortened due to uneven charging and discharging reactions in lithium secondary batteries. Since the position of the negative electrode plate is regulated, assembly can be performed with high precision and is easy.

In the above embodiment, the negative electrode plates are aligned and arranged between the positive electrode plates that are alternately and regularly folded, but as shown in the cross-sectional configuration diagram of still another structural example of the electrode plate group in FIG. The negative electrode plates (2) may be arranged to be alternately shifted in the width direction, and in this case, the positive electrode plates (1)
This makes it possible to improve the facing area ratio of the negative electrode plate (2) and to obtain a battery with good volumetric efficiency.

Fig. 8 is also a cross-sectional configuration diagram showing another example of the structure of the electrode plate group, in which the positive electrode plate (1) is folded so as to be wrapped in a certain direction while the negative electrode plate (2) is inserted between them. By adopting such a structure, the manufacturing process for assembling the electrode plate group can be further simplified.

Furthermore, in the above embodiments, the case where the positive electrode plate is folded or wound in the form of a continuous band is explained, but the negative electrode plate may be folded or wound as a continuous band. good.

[Effects of the Invention] As described above, according to the present invention, a positive electrode plate (or a negative electrode plate mainly composed of lithium) having a continuous band-shaped rechargeable active material is folded or wound in a zigzag shape, The above-mentioned negative electrode plate (or positive electrode plate) was placed between each with a separator in between to form an electrode plate group, and this was housed in a rectangular container to form a square lithium secondary battery. This has the effect of simplifying the manufacturing of the plates and assembling the electrode plate group, thereby reducing manufacturing costs.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional configuration diagram showing an example of the electrode plate group according to the present invention, and FIGS. 2(a) and 2(b) show the structure of the positive electrode plate in FIG. 1. (a) is a front view; b) is a side view, FIGS. 3(a) and 3(b) show the structure of the negative electrode plate equipped with a separator, (a) is a front view, (b) is a side view, and FIG. 4 is a side view. FIG. 1 is a cross-sectional configuration diagram showing a square lithium secondary battery according to an embodiment of the present invention in which the electrode plate group shown in FIG. 1 is housed in a square container, and FIG. 5 is another structure of the electrode plate group according to the present invention. 6(a) and 6(b) show the structure of the positive electrode plate in FIG. 5. (a) is a front view, (b)
) is a side view, FIGS. 7 and 8 are cross-sectional configuration diagrams showing still other structural examples of the electrode plate group according to the present invention, and FIG. 9 is a cross-sectional configuration diagram showing a conventional prismatic two-cadmium battery. Fig. 10 is a schematic plan view showing the structure of the positive electrode plate of a conventional prismatic lithium secondary battery, Fig. 11 is a schematic plan view showing the structure of the negative electrode plate, and Fig. 12 is the same prismatic lithium secondary battery. FIG. 2 is a cross-sectional configuration diagram showing a battery. In the figure, (1) is a strip-shaped positive electrode plate, (lb) is an active material, (2) is a negative electrode plate, (3) is a separator, and (4) is a battery storage case which is a rectangular container. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] In a prismatic lithium secondary battery, a prismatic lithium secondary battery is constructed in which a prismatic container houses a stack of electrode plates, in which a negative electrode plate mainly composed of lithium and a positive electrode plate having a rechargeable active material are stacked facing each other with a separator in between. The strip-shaped positive electrode plate (or negative electrode plate) is folded or wound in a zigzag shape, and the negative electrode plate (or positive electrode plate) is arranged between each with a separator therebetween to form the electrode plate group. A prismatic lithium secondary battery characterized by: