JP3413907B2 - Non-aqueous electrolyte secondary battery and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte secondary battery and a method for manufacturing the same, and more particularly to improvement of battery performance such as cycle characteristics thereof.

[0002]

2. Description of the Related Art Recent remarkable advances in electronic technology have made electronic devices smaller and lighter one after another. Along with this, batteries, which are used as mobile power sources, are required to be smaller and lighter and have high energy density.

Conventionally, an aqueous solution type secondary battery such as a lead battery or a nickel-cadmium battery has been mainly used as a secondary battery for general use. However, although these aqueous secondary batteries have excellent cycle characteristics, they cannot be said to be sufficiently satisfactory in terms of battery weight and energy density.

Therefore, recently, a material capable of doping and dedoping lithium ions such as lithium, a lithium alloy and a carbon material is used as a negative electrode, and a lithium composite oxide such as a lithium cobalt composite oxide is used as a positive electrode. Research and development of a non-aqueous electrolyte secondary battery using a battery have been actively conducted. This battery has a high battery voltage, a high energy density, and excellent cycle characteristics.

[0005]

By the way, in a flat plate type non-aqueous electrolyte secondary battery, its electrodes are a negative electrode obtained by applying a negative electrode active material to a negative electrode current collector and a positive electrode current collector. A positive electrode formed by applying an active substance is arranged with a separator interposed therebetween, and a plurality of sets of these electrodes are stacked to form a laminated electrode body. At this time, in the conventional non-aqueous electrolyte secondary battery, in order to prevent the laminated electrode body from losing its shape in the battery container, the laminated electrode body is wound and held using a tape, and the laminated electrode body is held in a taped state. The laminated electrode body is inserted into the battery container and accommodated therein.

However, with repeated use, the non-aqueous electrolyte in which the laminated electrode body is immersed in the battery container causes the tape to deteriorate and swell. As a result, looseness occurs between the electrodes constituting the laminated electrode body, causing a collapse of the mold, resulting in significant deterioration of battery performance such as battery capacity, cycle characteristics and heavy load characteristics.

In the non-aqueous electrolyte secondary battery, when charging and discharging are repeated, the electrodes constituting the laminated electrode body in the battery container expand and contract depending on the charging and discharging. . Along with that, the pressure applied between the electrodes is repeatedly increased and decreased, and the collapse of the laminated electrode body is promoted each time, and the battery performance such as battery capacity, cycle characteristics and heavy load characteristics is further rapidly deteriorated. Will result.

Furthermore, the non-aqueous electrolyte secondary battery is designed so that the space inside the battery container can accommodate the laminated electrode body just because of the demand for miniaturization. Therefore, in the prior art, since the tape is wound around the laminated electrode body and inserted and accommodated in the battery container in the state of being held, the bundle of the electrodes aligned at the time of this insertion collapses, resulting in a defect during battery production. There is a problem that the generation rate is large and the yield is significantly reduced.

The present invention has been made in view of the above problems, and it is an object of the present invention to increase the battery capacity and significantly improve the cycle characteristics and the heavy load characteristics. It is an object of the present invention to provide a non-aqueous electrolyte secondary battery and a method for manufacturing the same, which can improve the accumulation and reduce the manufacturing cost.

[0010]

DISCLOSURE OF THE INVENTION The present invention provides a non-aqueous electrolyte secondary battery in which a flat plate type battery container having electrode terminals and a laminated electrode body formed by laminating sheet-like or plate-like electrodes are housed. The laminated electrode body is sandwiched between leaf springs having a pair of spring pieces formed by bending one continuous member, and both main surfaces thereof are pressed by the spring pieces in the battery container. Configure.

In this case, the pressing member is installed such that both side surface portions of the pressing member are substantially parallel in the battery container.

Further, the laminated electrode body is sandwiched by a leaf spring having a pair of spring pieces which are formed by bending one continuous member and are biased outward, and the laminated electrode body sandwiched by the leaf springs. A non-aqueous electrolyte secondary battery is manufactured by housing the spring piece in a battery container against the elastic force.

[0013]

In the non-aqueous electrolyte secondary battery according to the present invention,
In the battery container, both side surface portions of the leaf spring-shaped pressing member exert pressure on the inner surface portion of the battery container due to its elastic force, and the reaction causes the laminated electrode body to be pressed from both side surfaces thereof. A constant pressure is applied to the electrodes, so that the electrode parts constituting the laminated electrode body are securely held in the aligned state when inserted into the battery container.

In this case, since both side portions of the pressing member are substantially parallel in the battery container, the pressure from the pressing member is evenly applied to the laminated electrode body. Is stably held in the battery container.

[0015]

EXAMPLES Examples of the non-aqueous electrolyte secondary battery according to the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the non-aqueous electrolyte secondary battery according to this embodiment is composed of an electrode laminate 1, a battery upper lid portion 2 and a battery container 3.

The electrode laminate 1 is composed of lithium doped and dedoped.
It is made of carbon material (eg KH carbon)
LiC, which is a negative electrode and a composite oxide of lithium and a transition metal
oO ₂The electrode part consisting of
A plurality of sets are arranged via a printer. Also, this
The positive electrode lead 11 and the negative electrode lead are provided on the upper surface of the electrode laminate 1 of
12 are installed respectively.

The battery upper lid portion 2 is electrically connected to the positive electrode lead 11 and the negative electrode lead 12, and has a positive electrode terminal 13 and a negative electrode terminal 14 which are electrically connected to these leads and a pressure increase in the battery during use of the battery. And a safety valve 15 for reducing the pressure.

The battery container 3 is in the shape of a thin casing having a substantially rectangular shape, and has an opening 3a in its upper part. A leaf spring shape having a pair of spring pieces formed by bending the electrode laminated body 1 into the battery container 3 from the opening 3a through a polyethylene sheet 16 and further by bending one continuous member outside the sheet 16. Are arranged via the pressing member 17. Then, a nonaqueous electrolytic solution obtained by dissolving an electrolyte in a nonaqueous solvent is injected from the opening 3a to immerse the electrode laminate 1, and the battery upper lid 2 is joined to the opening 3a using ultrasonic waves or thermocompression bonding. By fixing and closing, the non-aqueous electrolyte secondary battery according to this example is configured.

The leaf spring-shaped pressing member 17 is made of a single continuous member made of stainless steel, and as shown in FIG.
a and side surface portions 17b and 17c are formed, and the side surface portions 17b and 17c are configured to have a shape that gently expands toward the end surfaces b and c.

In the battery container 3, as shown in FIG. 2, the pressing member 17 has a first part depending on the shape of the battery container 3.
The side surface portion 17b and the side surface portion 17c of No. 7 have a substantially parallel shape. Then, the electrode laminate 1 has its main surfaces 1a and 1b.
In the state of being constantly pressed by the side surfaces 17b and 17c of the pressing member 17 (this pressing force is 0.01 kg / c
m ² or more).

Now, a method of manufacturing the non-aqueous electrolyte secondary battery according to the above embodiment will be described. First, the electrode stack 1 is made of KH carbon, which is a carbon material capable of doping and dedoping lithium, as a material, a negative electrode having a thin rectangular shape, and Li, which is a composite oxide of lithium and a transition metal.
A positive electrode made of CoO ₂ and having a thin rectangular shape,
Polyethylene or polypropylene is used as a material, and an electrode portion is formed through a separator having a thin rectangular shape similarly. Then, a plurality of sets of these electrode portions are superposed on each other, and the positive electrode lead 11 and the negative electrode lead 12 are placed and fixed on the upper surface thereof to produce the electrode laminate 1 (electrode laminate producing step S
1).

As for the battery upper lid portion 2, a positive electrode terminal 13 and a negative electrode terminal 14 are provided on both ends of a plate-like member having a rectangular shape, which is made of the same material as that of a battery container 3 to be described later, and further the above-mentioned plate is provided. The battery upper lid portion 2 is manufactured by installing a safety valve 15 for reducing a pressure increase in the battery during use of the battery at substantially the center of the battery-shaped member (upper lid portion manufacturing step S2).

Further, the battery container 3 is made of metal (for example, iron) or a synthetic resin such as polyethylene or polypropylene, has a substantially rectangular thin casing shape, and an opening 3a is formed on the upper portion thereof to form a battery. The container 3 is manufactured (battery container manufacturing step S3).

Here, before the battery upper lid 2 is bonded and fixed to the opening 3a, Ni plating is applied to the inner surface or the outer surface of the battery container 3 in consideration of the improvement of heat dissipation to form a Ni plating layer. Good. In this case, if the joint portion 3b of the battery container 3 is plated with Ni, there arises a disadvantage that welding is difficult at the time of joining. Therefore, the joint portion 3b is masked and the battery container 3 is plated with Ni. It is preferable to apply.

Next, a plate-shaped member made of stainless steel and having a rectangular shape is bent in parallel at two positions equidistant from the ends b and c, and the bottom 17a and the side 17 are formed.
b and 17c are formed to manufacture the leaf spring-shaped pressing member 17 (pressing member manufacturing step S4).

Then, the positive electrode lead 11 and the negative electrode lead 12 of the electrode laminate 1 produced as described above and the battery upper lid portion 2 are formed.
After connecting the positive electrode terminal 13 and the negative electrode terminal 14 to each other to make them conductive, the bottom surface portion 1c of the electrode laminate 1 is placed on the bottom surface portion 17a of the pressing member 17 and the polyethylene sheet 16 is formed.
Place through. Then, in this state, the non-aqueous electrolyte solution obtained by dissolving the electrolyte in the non-aqueous solvent is poured from the opening 3a of the battery container 3 into the battery container 3 against the resilience of the pressing member 17 to be housed. The joint portion 3b of the battery container 3 and the joint portion 2b of the battery upper lid portion 2 are joined and fixed by using ultrasonic waves or thermocompression bonding to close the non-aqueous electrolyte secondary battery according to the above embodiment. Create. (Battery assembly step S5).

In the non-aqueous electrolyte secondary battery according to the above-mentioned embodiment, the side surface portions 17b and 17c of the leaf spring-shaped pressing member 17 in the battery container 3 are elastic due to the battery container 3
Since the laminated electrode body 1 is pressed from both side surfaces 1a and 1b by a pressure exerted on the inner surface portion of the laminated electrode body 1, a pressure is constantly applied to the laminated electrode body 1 and the laminated electrode body 1
The respective electrode parts constituting the are securely held in an aligned state when inserted into the battery container 3.

Therefore, during charging and discharging of the battery, the laminated electrode body 1 is unlikely to lose its shape even if the electrode parts constituting the laminated electrode body 1 repeatedly expand and contract, and the durability of the battery is greatly improved. It is possible to improve the battery performance such as cycle characteristics and heavy load characteristics.

Further, since the side surface portions 17b and 17c of the leaf spring-shaped pressing member 17 are substantially parallel to each other in the battery container 3, the pressure from the pressing member 17 is uniformly applied to the laminated electrode body 1. The laminated electrode body 1 is stably held in the battery container.

Therefore, each electrode part constituting the laminated electrode body 1 can function uniformly and evenly over the entire surface thereof, so that the battery capacity can be improved and the battery performance (energy density, power density, cycle characteristics, etc.) can be improved. It is possible to prevent the deterioration of (1) and further improve the durability of the battery.

Moreover, since it is very easy to store the laminated electrode body 1 in the battery container 3, it is possible to save the labor at the time of manufacturing and inspecting the battery, and to greatly improve the yield at a low cost. Becomes

[0033]

According to the non-aqueous electrolyte secondary battery of the present invention, a flat plate type battery container having an electrode terminal on one end side including the thickness direction is formed into a sheet or plate shape in the thickness direction of the battery container. In a non-aqueous electrolyte secondary battery containing a laminated electrode body formed by stacking the above electrodes, a plate made of one continuous member for pressing the laminated electrode body from both sides of its main surface in the battery container. Since the spring is housed, the battery capacity can be increased, the cycle characteristics and the heavy load characteristics can be significantly improved, and the yield can be improved to reduce the manufacturing cost.

Further, according to the method for producing a non-aqueous electrolyte secondary battery according to the present invention, a flat plate type battery container having an electrode terminal on one end side including the thickness direction is formed into a sheet shape in the thickness direction of the battery container. Alternatively, in the method of manufacturing a non-aqueous electrolyte secondary battery containing a laminated electrode body formed by laminating plate-shaped electrodes, a step of sandwiching and holding the laminated electrode body in a leaf spring made of one continuous member, Since the laminated electrode body held by the leaf spring is manufactured in the battery container, the non-aqueous electrolyte secondary battery is manufactured by going through the process of fixing and closing the battery upper lid part.
It is possible to manufacture a non-aqueous electrolyte secondary battery that increases battery capacity and significantly improves cycle characteristics and heavy load characteristics, and further, it is possible to improve yield and reduce manufacturing cost. .

[Brief description of drawings]

FIG. 1 is an exploded perspective view schematically showing a non-aqueous electrolyte secondary battery according to an example of the present invention.

FIG. 2 is a cross-sectional view schematically showing the inside of the battery container of the non-aqueous electrolyte secondary battery according to the present embodiment.

[Explanation of symbols]

1 ... laminated electrode body 2 ... Battery top cover 3 ... Battery container 17 ... Pressing member

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01M 10/38 H01M 10/40

Claims (3)

(57) [Claims] 1. A flat battery container having electrode terminals ,
In a non-aqueous electrolyte secondary battery containing a laminated electrode body formed by laminating sheet- shaped or plate-shaped electrodes, the laminated electrode body is formed by bending one continuous member. It is sandwiched between leaf springs that have a pair of spring pieces .
A non-aqueous electrolyte secondary battery, wherein both main surfaces of the battery container are pressed by the spring pieces in the battery container. 2. The non-aqueous electrolyte secondary battery according to claim 1, wherein both side surfaces of the leaf spring are substantially parallel in the battery container. 3. A flat battery container having electrode terminals,
Stacked electrode assembly made by stacking sheet-shaped or plate-shaped electrodes
The method of manufacturing a nonaqueous electrolyte secondary battery capacity, the laminated electrode body was sandwiched a plate spring having a pair of spring pieces being urged the one continuous member to be outwardly and bent form, the laminated electrode body is sandwiched the plate spring, to characterized in that housed in the battery container against the resilient force of the spring piece
Non-aqueous electrolyte secondary battery manufacturing method.