JPH07249403A - Layered battery and manufacture thereof - Google Patents

Abstract

PURPOSE:To increase position accuracy and prevent internal short circuit to improve reliability and mass productivity by providing electric insulating layers in the peripheral edge parts of positive or negative electrodes to form the positive electrodes and solid electrolyte films to them by coating or a printing method. CONSTITUTION:Unhardened paste, wherein active material and a conductive agent are mixed with a high molecular solid electrolyte, is applied by coating or printing onto the aluminium foil 2 of a positive electrode collector, and then is hardend to form a positive electrode 1. Like the positive electrode 1, the same paste is applied onto the positive electrode 1 to be hardened to form a high molecular solid electrolyte film 3, and a negative electrode 4 composed of lithium foil is pressed onto the copper foil 5 of a negative electrode collector. Then a window-like electric insulating layer 6 is coated on the peripheral edge part of the foil 2 to be formed slightly larger than the positive electrode 1 and the film 3 to insert the negative electrode 4 in the window frame of the layer 6. These are enclosed in casings 7 and 8 of stainless foil doubling as the negative and positive electrodes to be fusedly sealed by sealing resin 9. Consequently, position accuracy can be increased to prevent internal short circuit to increase reliability and mass productivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated battery in which a lithium or lithium occlusion electrode is used for a negative electrode, a polymer solid electrolyte is used as an electrolyte, and a plurality of positive electrodes, negative electrodes and electrolyte layers are laminated.

[0002]

2. Description of the Related Art In a conventional laminated battery, a positive electrode, a separator impregnated with an electrolyte, and a negative electrode, which are cut into a predetermined size in a casing, are repeatedly stacked in this order. The size of the separator is made equal to the size of the electrode in order to prevent a short circuit at a portion, and the positional accuracy of the positive electrode, the separator, and the negative electrode during stacking cannot be slightly changed.

[0003]

In the conventional stack type battery described above, when a separator is larger than an electrode, a short circuit occurs when adjacent separators are in contact with each other, and when the electrodes are larger than the separator, they are opposed to each other. Even if the positive electrode and the negative electrode are in contact with each other, a short circuit occurs. Further, regardless of the size relationship between the electrode and the separator, a short circuit may occur due to the displacement of the position of the electrode and the separator. Therefore, in the conventional battery structure, and in the conventional manufacturing method of cutting and stacking the film-formed electrodes and separators in advance, the accuracy of the size and position of the electrodes and the separator is strict, and it is not suitable for mass production.

[0004]

The laminated battery of the present invention comprises:
In order to achieve the above object, the following structure is provided, and it is manufactured by the following manufacturing method. That is, in the battery of the present invention, a plurality of positive electrodes, a solid electrolyte, and a negative electrode are laminated in this order in a casing, but a window frame shape is formed on the peripheral portion of at least one of the positive electrode and the negative electrode. A thin layer of electrically insulating material is arranged. The outer dimension of the window frame-shaped electrically insulating layer is equal to or larger than the sizes of the electrode and the polymer solid electrolyte film (hereinafter referred to as solid electrolyte film). The size of the other electrode is equal to or smaller than the inner dimension of the window frame-shaped electrically insulating layer.

The window frame-shaped electrically insulating layer prevents the opposing positive electrode and negative electrode and the adjacent solid electrolyte films from contacting each other at the edge portion to cause an internal short circuit of the cell. The outer dimension of the window-frame-shaped electrically insulating layer is equal to or larger than the size of the electrode and the solid electrolyte film, and an internal short circuit does not occur even if an error (variation) occurs in the size of the electrode and the solid electrolyte film. For the same reason, internal short circuit does not occur even if an error occurs in the position where the positive electrode, the solid electrolyte film, and the negative electrode are laminated.

The laminated battery of the present invention comprises at least a positive electrode,
The solid electrolyte film and the window frame-shaped electric insulation layer are formed by coating or printing. Therefore, as compared with the conventional method of cutting and stacking the electrodes and separators formed in advance, the positional accuracy is remarkably improved, which is advantageous from the viewpoint of preventing internal short circuit.

[0007]

In the laminated battery of the present invention, by disposing an electrically insulating layer on the peripheral portion of at least one of the positive electrode and the negative electrode, the positive and negative electrodes facing each other at the edge portion and the solid electrolyte film adjacent to each other Prevents mutual contact and cell short circuit. Further, by forming and stacking the positive electrode and the solid electrolyte film by coating or printing, the positional accuracy of the electrode and the solid electrolyte film is improved, and it is also effective in preventing internal short circuit.

The laminated battery of the present invention is a battery which is highly reliable and suitable for mass production without fear of internal short circuit even if there is an error in size and position of the electrode and the solid electrolyte film when laminated. is there.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a laminated lithium battery according to the present invention. In FIG. 1, 1 is a positive electrode, and manganese dioxide, which is an active material, and acetylene black, which is a conductive agent, are mixed with an uncured polymer solid electrolyte to form a paste, which is coated on an aluminum foil 2 which is a positive electrode current collector. It is applied by printing and then cured. The polymer solid electrolyte is obtained by dissolving lithium perchlorate in a polyether polymer. The thickness of the positive electrode 1 is about 100 μm. 3 is a solid polymer electrolyte film, which is an uncured substance having the same composition as that used for the positive electrode, coated on the positive electrode 1 by coating or printing, and then cured, and has a thickness of about 3
It is 0 μm. Reference numeral 4 denotes a negative electrode made of a lithium foil, which has a thickness of about 70 μm and is pressure-bonded onto the copper foil 5 of the negative electrode current collector. Reference numeral 6 is a window frame-shaped electric insulating layer arranged on the positive electrode side.
The electrical insulation layer 6 is made of hot melt resin and is coated on the edge portion of the aluminum foil 2 of the positive electrode current collector. The outer dimension of the electrical insulation layer 6 is slightly larger than that of the positive electrode 1 and the solid electrolyte film 3. Lithium foil 4
The size of the negative electrode composed of the copper foil 5 and the copper foil 5 is slightly smaller than the inner dimension of the electric insulating layer 6 so that the negative electrode fits into the window frame of the electric insulating layer. 7 and 8 are casings made of stainless steel foil, which also serve as a negative electrode terminal and a positive electrode terminal, respectively. A sealing resin 9 made of a heat-fusible resin is fused to the stainless steels 7 and 8.

In the above embodiment, the positive electrode was applied on an aluminum foil and cut into a predetermined size. The negative electrode was prepared by pressing a lithium foil onto a copper foil and cutting it into a predetermined size. However, by using a conductive paste instead of a metal foil for the current collector and a powdered lithium alloy instead of a lithium foil for the negative electrode, it is possible to use the coating method for all the stacking steps. That is, a conductive paste composed of carbon and a binder resin is applied on the stainless steel foil and then cured. A positive electrode and a solid electrolyte film are laminated thereon by coating in the same manner as in the above embodiment. Further, a negative electrode paste obtained by mixing the lithium aluminum alloy powder and the uncured solid polymer electrolyte is applied and cured. A plurality of electrodes and a solid electrolyte film are laminated by repeating the same process of coating and hardening the above-mentioned conductive paste thereon. According to this method, it is possible to improve the dimensional accuracy and the positional accuracy of the electrodes and the solid electrolyte film, and to manufacture a battery of higher reliability, as compared with the case where the film is formed in advance and then cut and laminated.

(Comparative Example) FIGS. 2 to 4 are sectional views of a laminated portion of an electrode and an electrolyte of a conventional laminated battery. As shown in Fig. 2, the size of the electrode, electrolyte and current collector are exactly the same,
There is no risk of internal short circuit if there is no position error. However, it is practically impossible to mass-produce such an error-free product. By the way, when there is an error in size and position as shown in FIG. 3 and FIG. 4, the positive electrode and the negative electrode facing each other contact at the edge portion and short-circuit. In addition to the short circuit caused by the contact between the solid electrolyte films, when the solid electrolyte film comes into contact with the aluminum of the positive electrode current collector, aluminum alloys with lithium to destroy the current collector.

[0012]

As described above in detail, the laminated battery according to the present invention is a highly reliable battery that is free from the risk of internal short-circuiting and has an extremely high industrial value suitable for mass production.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a stacked battery according to the present invention.

FIG. 2 is a cross-sectional view of an electrode and a laminated portion of an electrolyte of a conventional laminated battery.

FIG. 3 is a cross-sectional view of a laminated portion of electrodes and an electrolyte of a conventional laminated battery.

FIG. 4 is a cross-sectional view of a laminated portion of an electrode and an electrolyte of a conventional laminated battery.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode 3 Solid electrolyte film 4 Negative electrode 6 Window frame-shaped electrical insulating layer

Claims (4)

[Claims] 1. A lithium battery comprising a solid polymer electrolyte, a positive electrode, and a negative electrode, wherein a plurality of electrolytes, the positive electrode, and the negative electrode are laminated, and a window frame shape is formed on the peripheral portion of at least one of the positive electrode and the negative electrode. A laminated battery comprising the electrically insulating layer of. 2. The laminated battery according to claim 1, wherein the outer dimension of the window frame-shaped insulator layer is equal to or larger than that of the solid polymer electrolyte, the positive electrode and the negative electrode. 3. The stacked battery according to claim 1, wherein the size of one of the positive electrode and the negative electrode is equal to or smaller than the inner dimension of the window frame-shaped insulating layer. 4. The method for producing a laminated battery according to claim 1, wherein at least the positive electrode, the solid polymer electrolyte layer and the insulating layer are formed by a coating method or a printing method.