JP2001283815A - Base material for secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate defects due to damages of a separator at time of battery assembly, to cope with miniaturization, light-weight, and larger capacity of a secondary battery. SOLUTION: A no-binder nonwoven fabric sheet with a double layer structure of a compact layer and a coarse layer of polyolefinic polymer resin fabrics made of a signal component and/or composite component is provided, the coarse layer making an electrode plate layer having a nickel coated film on its surface fiber structure and the compact layer making a separator layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to Ni used in mobile phones, personal computers, electric vehicles and the like.
The present invention relates to a base material for a secondary battery in which an electrode plate and a separator used for a secondary battery such as a Cd battery and a Ni-H battery are integrated.

[0002]

2. Description of the Related Art In this type of secondary battery, a non-woven fabric sheet made of a nickel porous sintered substrate, a foamed nickel substrate, or a metal fiber substrate as an electrode plate and a nylon fiber or a polypropylene fiber as a separator is generally used.

[0003] Each battery maker uses an electrode plate and a separator that are separately manufactured, alternately laminates an electrode plate and a separator filled with an active material that differs according to battery characteristics, and winds the electrode plate in a spiral shape. The secondary battery is manufactured by charging the battery case, injecting the electrolyte, and packing.

[0004] Advances in electronics have made it possible to reduce the size and weight of electronic devices, and accordingly, there has been a demand for smaller, lighter, and higher capacity secondary batteries. In order to achieve this demand, the weight and volume of the electrode plate and the separator, which are materials other than the active material, must be reduced.

However, according to the prior art, since the electrode plate and the separator are made of different materials, there is naturally a limit in reducing the weight and thickness, and it is difficult to cope with the reduction in size and weight of the secondary battery. The gap between the electrode plate and the separator is apt to be formed due to poor adaptation when laminating and winding, which causes a decrease in liquid retention and an increase in internal impedance, which is an obstacle to increasing the capacity of the secondary battery. I have. In addition, a breakage accident (defective product) of the separator due to the electrode plate occurs, which causes a decrease in yield. Furthermore, the work of assembling the battery is difficult, which is an obstacle to miniaturization.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a secondary battery which can be made smaller, lighter, and have a higher capacity, and which eliminates the occurrence of defective products due to separator breakage during battery assembly work. I do.

[0007]

The base material for a secondary battery according to the present invention is composed of a polyolefin polymer resin fiber consisting of a single component and / or a composite component, and is composed of a dense layer and a coarse layer. It is a non-binder nonwoven fabric sheet having a structure, wherein a rough layer is an electrode plate layer having a nickel plating film on the surface of its constituent fibers, and a dense layer is a separator layer.

According to this means, since the electrode plate layer and the separator layer are a binderless nonwoven fabric sheet integrally formed of the same type of polymer resin fiber, the weight and thickness of each layer and the whole are adjusted to the utmost. In addition to simplifying the work of tightening the battery at the time of manufacturing the battery, no delamination or floating phenomenon occurs even if the battery is formed into a complicated shape. Accordingly, unevenness of impregnation of the electrolyte and a decrease in the internal impedance are prevented, the capacity can be increased, and the performance can be improved by increasing the attached amount of the active material. Furthermore, the breakage of the separator due to the electrode plate, which occurred during the production of the battery, is also eliminated, and the production efficiency can be greatly improved.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, A is a base material for a secondary battery, and the base material A for a secondary battery is composed of a polypropylene fiber and a polypropylene-polyethylene composite fiber, and a separator layer a, which is a dense layer in a thickness direction, and a rough layer. The electrode plate layer b is made of a binderless nonwoven fabric which is integrally laminated by fusing the constituent fibers and between the layers by melting the polyethylene component. The electrode plate layer b
As shown in FIG. 2, a nickel-plated film 3 is formed on the fiber surface of a core-sheath composite fiber 2 composed of a polypropylene fiber 1 and a polypropylene component 2a-polyethylene component 2b.

In this case, the core-sheath type is used as the conjugate fiber, but it may be a side-by-side type, and a heat-adhesive fiber composed of a single component may be used instead of the conjugate fiber.

Incidentally, the base material for a secondary battery according to the present invention can be manufactured, for example, by the following method.

That is, 50 to 70% of 2.2 to 3.3 dtex polypropylene fibers and 2.2 to 3.3 dtex
50-30% of polyethylene-polypropylene composite fiber
To produce a fiber aggregate having a coarse fiber density
A dense fiber aggregate having a fiber density of 50 to 70% of a polypropylene-polyethylene composite fiber of dtex or less and 50 to 30% of a polypropylene fiber of 1.1 dtex or less is produced. Next, these fiber aggregates are laminated, subjected to a hot air treatment, melted only the polyethylene component, and fused between the constituent fibers and between the layers, so that a coarse layer having a predetermined thickness and a dense layer are integrated. Form a binder nonwoven sheet.
Subsequently, the non-binder non-woven fabric sheet is subjected to a masking treatment with a fluorine-based water repellent on the dense layer, and then subjected to electroless nickel plating. It is possible to manufacture a base material for a secondary battery in which an electrode plate layer whose surface is nickel-plated and a separator layer formed by further removing a fluororesin of a dense layer by washing are integrally entangled.

In this case, the thicknesses of the coarse layer and the dense layer are not particularly limited.
0-3.0mm, 0.15-0.25m for dense layer
The range of m is preferred.

[0015]

EXAMPLES For the separator layer, polypropylene fiber 1.1 dtex 30% and polypropylene-polyethylene core-sheath composite fiber 1. A high-density fiber aggregate having a weight of 70 g / m ² was prepared using a card machine and a land machine with 70% dtex.
In addition, for the electrode plate layer, a polypropylene fiber of 2.2 dt is used.
ex70% and polypropylene-polyethylene core-sheath composite fiber 2.2 dtex 30% with a card machine and a land machine with a weight of 7
A low-density fiber aggregate of 0 g / m ² was produced. Subsequently, both fiber aggregates were laminated, and dried air at a temperature of 150 ° C. was transmitted therethrough to produce a binderless nonwoven fabric sheet in which the constituent fibers of each layer and the layers were adhered by a polyethylene component having a sheath. At this time, the thickness on the separator layer side is 0.15 m.
m, and the thickness of the electrode plate layer side was 4.0 mm.

Next, only the separator layer side of the above non-binder nonwoven fabric sheet was roll-coated with a water-repellent resin solution having the following composition conditions to prepare a one-sided water-repellent composite sheet.

Blending conditions Solid ratio Methanol-soluble acrylic resin 100 parts Fluorine-based water repellent 100 parts Polymer thickener 5 parts Concentration 20% Adhesion amount 20 g / m ² Viscosity 1,000 cps (viscosity for roll coating film thickness)

Next, the one-sided water-repellent composite sheet is subjected to electroless nickel plating so that the electrode plate weight becomes 1,000 g / m ² , and the product weight is 1,090 g / m ² , A single-sided nickel-plated composite sheet having a total thickness of 4.15 mm, which was not plated but was plated only on the electrode layer side, was produced.

Subsequently, the one-side nickel-plated composite sheet is immersed in a 10% methanol solution to wash and remove the fluororesin adhering to the surface of the constituent fibers on the separator layer side. Then, the electrode plate layer was calendered to 2.0 mm to obtain a secondary battery base material having a weight of 1,070 g / m ² and a total thickness of 2.15 mm.

[0020]

According to the present invention, the weight and thickness of the electrode plate layer and the separator layer can be adjusted and reduced to the utmost limit. Higher performance can be accommodated, and if importance is placed on size, lighter and thinner can be achieved, and smaller and lighter batteries can be accommodated. In addition, even when the battery is formed into a complicated shape corresponding to the shape of the battery, no delamination or floating phenomenon occurs, and it is possible to prevent unevenness of impregnation of the electrolyte and a decrease in internal impedance. Furthermore, the separator breakage that occurred during the fabrication of the battery due to the electrode plate and the preparation of multiple materials
Work such as storage is reduced, and effects such as improvement in productivity can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic enlarged view of a secondary battery base material of the present invention.

FIG. 2 is a schematic enlarged view of constituent fibers of an electrode layer.

[Explanation of symbols]

 A: Secondary battery substrate a: Separator layer b: Electrode plate layer . . 1. polypropylene fiber . . 2. Composite fiber 2a: polypropylene component 2b: polyethylene component . . Nickel plating film

Claims (1)

[Claims] 1. A composition comprising a single component and / or a composite component,
It is a binderless nonwoven fabric sheet having a two-layer structure of a dense layer and a coarse layer with a polyolefin-based polymer resin fiber, and the coarse layer is an electrode plate layer having a nickel plating film on the surface of the constituent fibers, and the dense layer is A base material for a secondary battery, which is a separator layer.