KR20030037771A - Li-ion polymer battery - Google Patents

Abstract

PURPOSE: A lithium ion polymer battery is provided, to improve the chemical resistance, the heat resistance and the scratch resistance, thereby minimizing the inferior ratio of the external appearance. CONSTITUTION: The lithium ion polymer battery comprises a battery cell which comprises a positive electrode and a negative electrode whose positive and negative terminals are connected electrically, for inducing the current generated inside to the outside, and a separator; and an insulating case or pouch(26) which seals the battery cell with exposing some part of the positive and negative terminals, whose internal surface is made of a heat-adhesive polyolefin-based resin(17), and which comprises a polyolefin-based resin layer(17), an Al layer(18), a Nylon layer(19) and a polyester-based resin layer(20) sequentially. Preferably the interface between the layers is coated with a urethane adhesive.

Description

Li-ion polymer battery

The present invention relates to a lithium ion polymer battery, and more particularly, to a lithium ion polymer battery having a sealing structure capable of minimizing appearance defects by enhancing chemical resistance, heat resistance, and scratch resistance.

As portable wireless device products such as video cameras, portable telephones, portable PCs, and electric bicycles, electric vehicles, and electric tools have become lighter and more functional, batteries used as driving power have increased in importance. Research is being done.

In particular, the lithium secondary battery that can be charged and discharged has three times higher energy density per unit weight and can be charged faster than conventional lead-acid batteries, nickel-cadmium batteries, nickel-hydrogen batteries, and nickel-zinc batteries. Development is underway.

Lithium secondary batteries may be classified into lithium metal batteries using a liquid electrolyte, lithium ion batteries, and lithium ion polymer batteries using a polymer solid electrolyte according to electrolyte types.

Lithium ion polymer batteries can be classified into fully solid lithium ion polymer batteries containing no organic electrolyte solution and lithium ion polymer batteries using gel polymer electrolyte containing organic electrolyte solution, depending on the type of polymer solid electrolyte.

However, in the case of the all solid lithium ion polymer battery, there is no problem of leakage of the organic electrolyte, but in the case of the lithium ion polymer battery, the problem of leakage of the organic electrolyte may occur.

For example, in the case of a general secondary battery, a metal can is used as an exterior material of the battery, and some primary batteries such as lithium batteries and lithium polymer secondary batteries use a multilayer film pouch composed of aluminum foil and various types of polymer films. Can be. Using a multilayer film pouch has the advantage of significantly reducing the weight of the battery than using a metal can.

1 is an exploded perspective view schematically showing the structure of a conventional lithium ion polymer battery.

Referring to the accompanying drawings, although not shown in detail, the lithium ion polymer battery has a structure in which a positive electrode plate, a negative electrode plate, and a separator in which an organic electrolyte is impregnated with an electrode active material filled in a grid are stacked. A battery cell 11 is provided.

In addition, a positive electrode tab (not shown) is formed at one side of the positive electrode plate, a negative electrode tab (not shown) is formed at one side of the negative electrode plate, and the positive electrode tab and the negative electrode tab are arranged side by side at a predetermined interval. The tabs are connected to the external circuit by being connected to the positive lead 14 and the negative lead 15.

The above-described battery cell 11, the positive electrode lead 14, and the negative electrode lead 15 are sealed by an insulating case 16 having a cover or sealed by a pouch (not shown) or the like. The insulating case 16 generally has a pouch form or a case form in which heat-adhesive materials are laminated on the upper and lower surfaces of the aluminum thin film, and the heat-adhesive materials are bonded to each other to seal the inside thereof. In addition, a portion of the positive electrode lead 14 and the negative electrode lead 15 is sealed by the insulating case 16 in an exposed state to the outside for electrical connection between the battery cell 11 and the outside.

In more detail, the process of sealing the battery cell 11 to the insulating case 16 is performed as follows.

First, only a portion of the positive lead 14 and the negative lead 15 is exposed to the outside of the insulating case 16. In this state, the cover of the insulating case 16 is covered. After that, heat and adhesive materials of the insulating case 16 are applied by applying pressure and heat to seal the battery.

The insulating case 16 or the multilayer film pouch used in the conventional lithium ion polymer battery is sequentially a polyolefin-based resin layer (Polyolepin Layer, 17), aluminum layer (AL / Aluminum Layer, 18), nylon layer (Ny) as shown / Nylon Layer, 19) is composed of a multi-layered film structure, but if the electrolyte solution on the outside of the pouch during the manufacturing process, acidic chemicals such as HF in the electrolyte solution may corrode the nylon layer and appearance defects may occur. That is, at present, when the electrolyte is deposited on the outside of the pouch during the process, it is not only cumbersome but also difficult to remove completely. Therefore, the electrolyte on the pouch outer layer corrodes the nylon layer during high temperature aging. .

Accordingly, an object of the present invention is to provide a lithium ion battery having a multilayer film pouch that is resistant to corrosion even when an electrolyte solution is deposited during the manufacturing process, and which has enhanced heat resistance and scratch resistance.

1 is a schematic perspective view of a conventional lithium ion polymer battery.

2 is a schematic perspective view of a lithium ion polymer battery according to an embodiment of the present invention.

<Description of Symbols for Major Parts of Drawings>

11 Battery cell 14 Anode lead

15 ... Negative lead 16, 26 ... Insulated case

17.Polyolefin resin layer

18.AL/Aluminum Layer

19 ... Ny / Nylon layer

20.Polyester layer

In order to achieve the above technical problem, the present invention provides a battery cell having a structure in which a positive electrode, a negative electrode, and a separator are electrically connected to a positive electrode terminal and a negative electrode terminal for guiding an internally generated current; And

A portion of the positive electrode terminal and the negative electrode terminal are exposed to the outside, and the battery cell, the positive electrode terminal and the negative electrode terminal are sealed, and an inner surface thereof is formed of a polyolefin-based resin which is a heat-adhesive material, and subsequently a polyolefin resin layer / Al It provides a lithium ion polymer battery comprising a; insulating case or pouch coated with a / Ny / polyester-based resin layer to form a multilayer film.

The polyolefin resin layer is preferably any one selected from the group consisting of polypropylene, chlorinated polypropylene, polyethylene, ethylene propylene copolymer, polyethylene and acrylic acid copolymer, and copolymer of polypropylene and acrylic acid.

In addition, the polyester resin layer It is preferably one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyester copolymers and polycarbonates.

In addition, the interface between each layer constituting the multi-layer film may further include applying a urethane adhesive.

Hereinafter, a lithium ion polymer battery according to an exemplary embodiment of the present invention will be described in more detail with reference to the accompanying drawings.

2 schematically illustrates a structure of a lithium ion polymer battery according to an embodiment of the present invention.

Referring to the drawings, a lithium ion polymer battery according to an embodiment of the present invention is not shown in detail, but a lithium ion polymer battery has a single gap between two cathode plates filled with an electrode active material in a grid. The negative electrode plate is inserted, and the battery cell 11 has a structure in which a separator is inserted between the positive electrode and the negative electrode. The separator is made of a porous material in which many ultra-fine pores form a network, and the inside of the pore includes an organic electrolyte impregnated when the separator is injected into the electrolyte.

In addition, although not shown in detail in the drawings, the positive electrode tab and the negative electrode tab are formed on one side of the positive electrode plate and the negative electrode plate constituting the battery cell 11, the positive electrode tab and the negative electrode tab are arranged side by side at regular intervals. Each of the tabs is connected to an external circuit by being connected to the positive lead 14 and the negative lead 15.

The above-described battery cell 11 and the positive electrode lead 14 and the negative electrode lead 15 are sealed by an insulating case 26 having a cover or sealed by a sealing means such as a pouch (not shown). For this sealing operation, as shown in the drawing, the positive lead 14 and the negative lead 15 are aligned in the vertical direction, and each of the tabs is thickened by a plurality of tabs, so that only the lead is drawn out to the outside. Bend and aligned The sealing means typically has a pouch form or a case form in which a heat-adhesive material is stacked on the upper and lower surfaces of the aluminum thin film. It seals the inside by allowing them to bond together.

In addition, at this time, the part of the positive electrode lead 14 and the negative electrode lead 15 is exposed to the outside of the insulating case 26 or the pouch for the electrical connection between the battery cell 11 and the outside, the insulating property Sealed by case 26 or pouch.

As described above, the insulating case 26 or the pouch is formed of a multilayer film, and the multilayer film is formed of a polyolefin resin 17 having an inner surface thereof as a heat-adhesive material, and an aluminum layer (Al / Aluminum layer) 18), a nylon layer (Ny / Nylon layer) 19, and a polyester resin layer (20).

Here, the polyolefin-based resin layer 17 is preferably any one selected from the group consisting of polypropylene, chloride polypropylene, polyethylene, ethylene propylene copolymer, polyethylene and acrylic acid copolymer and copolymer of polypropylene and acrylic acid, It is more preferable that it is a polypropylene chloride or a copolymer of polypropylene and acrylic acid. The polyolefin-based resin layer 17 serves to electrically shield the battery cell 11 by having heat adhesiveness and insulation.

The aluminum layer 18 prevents penetration of moisture, air, and the like into the battery, and serves as a substrate for maintaining the strength of the multilayer film.

On the other hand, the nylon layer 19 has a predetermined hardness, ductility and insulation to protect the inner layer.

In addition, the polyester resin layer 20 is preferably any one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyester copolymer and polycarbonate, polyethylene terephthalate or poly It is more preferable that it is butylene terephthalate. The role of the polyester-based resin layer is to strengthen the chemical resistance, heat resistance and scratch resistance of the nylon layer, according to a preferred embodiment of the present invention, the melting point of the polybutylene terephthalate is 200-250 ℃ as a strong heat When exposed, it is more resistant to scratches and stresses because it can withstand heat transmitted from the outside more effectively than nylon and the strength of the material itself is high.

In addition, each interface between the layers by using a strong adhesive to improve the adhesive strength and tensile strength, etc. by the separation of each layer of the multilayer membrane due to the electrolyte infiltration after a long time, due to separation, detachment phenomenon, dropping, etc. It is desirable to prevent the insulating case 26 or pouch from being damaged due to the impact. At this time, the adhesive is preferably an adhesive containing a urethane-based resins.

In addition, as another feature of the present invention, when inserted into the outer packaging container (not shown) in the sealed state with the insulating case 26 or pouch as described above, although not shown, the edge of the heat-adhesive material is bonded to each other By folding the sealing part and inserting it into the outer packaging container, shrinking and packing the volume, it has the effect of light and small and short, and also increases the reliability and completeness of the battery by reducing the flow space inside the outer packaging container.

In addition, the positive lead 14 and the negative lead 15 exposed to the outside of the insulating case 26 or the pouch are welded to the inner exposed portion of the terminal unit which is installed in the outer packaging container and electrically connected to the outside.

In the multilayer pouch, the thickness of each polymer layer is 10-40 µm, and the thickness of the aluminum layer is preferably 100 µm or less.

As described above, the lithium ion polymer battery according to the present invention is excellent in corrosion resistance to the electrolyte, heat resistance to heat transmitted from the outside is strong, water absorption is low, and scratch resistance is strong because it can reduce the appearance defect rate have.

Claims (4)

A battery cell having a structure in which a positive electrode, a negative electrode, and a separator are electrically connected to a positive electrode terminal and a negative electrode terminal for guiding an internally generated current; And A portion of the positive electrode terminal and the negative electrode terminal are exposed to the outside, and the battery cell, the positive electrode terminal and the negative electrode terminal are sealed, and an inner surface thereof is formed of a polyolefin-based resin which is a heat-adhesive material, and subsequently a polyolefin resin layer / Al An insulating case or pouch formed by coating a multilayer film with a / Ny / polyester-based resin layer; Lithium ion polymer battery comprising a. The method of claim 1, wherein the polyolefin resin layer is any one selected from the group consisting of polypropylene, chlorinated polypropylene, polyethylene, ethylene propylene copolymer, polyethylene and acrylic acid copolymer and polypropylene and acrylic acid copolymer Lithium ion polymer battery. The lithium ion polymer battery of claim 1, wherein the polyester-based resin layer is any one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyester copolymer, and polycarbonate. . The lithium ion polymer battery according to any one of claims 1 to 3, wherein the interface between the layers forming the multilayer film further includes a urethane adhesive.