JPH07220753A - Set battery structure - Google Patents

Abstract

PURPOSE:To provide a set battery increasing volumetric energy density and weight energy density. CONSTITUTION:In a single battery used in a set battery structure, a layer-built electrode body 1 of laminating flat plate-shaped or sheet-shaped electrodes is sealed in a battery vessel 5 with at least one side surface flexible. A plurality of these single batteries are laminated in parallel to a laminating direction of the layer-built electrode body and received to a set battery vessel 20. This set battery vessel 20 is sealed and pressure charged with a non-combustible fluid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an assembled battery structure suitable for application to, for example, batteries for electric power storage and batteries for electric vehicles.

[0002]

2. Description of the Related Art In recent years,
Due to problems such as energy saving and environmental pollution, there is a strong demand for development of batteries for power storage and for use in electric vehicles and the like. With these batteries, high voltage (tens to hundreds of volts),
High energy capacity and energy density are required.

On the other hand, the structure of the unit cell used is generally of two types: a spiral type formed by winding a long electrode, and a flat rectangular type formed by laminating flat plate electrodes.

The spiral structure type battery has a relatively large load area because of its large electrode area, but has a bad space factor due to its cylindrical shape. In particular, a plurality of unit cells are used at the same time. At that time, the volume energy density is lowered. Further, the storage heat due to the heat generated during charging / discharging is large, and the battery characteristics are greatly deteriorated.

On the other hand, the flat rectangular battery has a good space factor and a small heat storage during charging / discharging, and is particularly useful as an assembled battery in which a plurality of cells used for electric vehicles are connected. Are suitable.

However, in a flat prismatic battery, it is known that if the adhesion between the electrodes is poor, a sufficient capacity cannot be obtained and at the same time, the cycle characteristics are significantly deteriorated. A conventional type of battery that has just been inserted is not yet sufficient.

Therefore, in order to improve the adhesion between the electrodes, it is conceivable to incorporate a spring for pressing the electrodes in the unit cell. However, if a spring for applying pressure is incorporated in the unit cell, the following problems occur. Will occur.

That is, the weight of the battery is large and the energy weight density is reduced. Further, a metal case having rigidity that can withstand the reaction force of the pressure spring in the unit cell is required, and the volume and weight of the unit cell increase together with the spring, and the energy density of the unit cell decreases. .

Further, in an assembled battery using a plurality of unit cells, useless volume and weight of the entire assembled battery are accumulated, and the energy density of the assembled battery is remarkably lowered.

The present inventors have already proposed, as a structure of a new unit cell and an assembled battery for solving the above-mentioned problems, a flat type unit cell in which a plurality of electrodes are laminated, and a spring for pressing an electrode is provided in the unit cell. A battery assembly structure using a plurality of unit cells having a battery case made of a thin flexible member having no rigidity is proposed (Japanese Patent Application No. 5-151339).

However, in the already-proposed battery pack structure, a mechanism for tightening the battery pack from both sides by using leaf springs, spring springs, etc. is used as a pressing method for the battery cells, which increases the weight and volume of the battery pack as a whole. Therefore, further improvement of energy density is required.

On the other hand, as a battery to be used, a non-aqueous electrolyte secondary battery using lithium or a lithium alloy as a negative electrode is promising as a battery capable of achieving high energy density, but the electrolyte to be used is an organic solvent. Therefore, if you use it in an electric vehicle etc. and the battery is destroyed due to a collision etc.,
There is a risk of ignition and explosion. The assembled battery does not have a self-extinguishing function to prevent this danger.

The present invention has been made in view of the above problems, and an object thereof is to provide an assembled battery having a high volume energy density and a high weight energy density. Another object is to provide an assembled battery having a self-extinguishing function even when the battery is destroyed.

[0014]

The assembled battery structure of the present invention houses a laminated electrode body 1 in which flat plate-shaped or sheet-shaped electrodes are laminated in a battery container 5 at least one side of which is flexible. In a battery pack structure in which a plurality of unit cells are stacked in parallel with the stacking direction of the stacked electrode bodies and housed in a battery pack container 20, the battery pack container 20
Is hermetically sealed and pressurized with a nonflammable fluid.

Further, the assembled battery structure of the present invention is the assembled battery structure having the above-mentioned structure, in which the nonflammable fluid is a deoxygenated gas.

Further, the assembled battery structure of the present invention is the assembled battery structure having the above-mentioned structure, in which the nonflammable fluid is an extinguishing fluid which is an extinguishing agent.

Further, the assembled battery structure of the present invention is the assembled battery structure having the above-mentioned structure in which the fire-extinguishing fluid is a liquid, or solid particles are dispersed in the liquid.

[0018]

According to the assembled battery structure of the present invention, a unit cell in which the laminated electrode body 1 in which flat plate-shaped or sheet-shaped electrodes are laminated is hermetically housed in the battery container 5 at least one side of which is flexible. In a battery pack structure in which a plurality of stacked electrode bodies are stacked in parallel with each other in the stacking direction and housed in a battery pack container 20, the battery pack container 20 is sealed and filled with a nonflammable fluid under pressure. Therefore, the volume energy density and the weight energy density can be increased, and even when the battery is destroyed, it has a self-extinguishing function.

[0019]

EXAMPLES Examples of the assembled battery structure of the present invention will be described below with reference to FIGS.

Example 1 First, a laminated electrode body was prepared. Here, as the laminated electrode body, two types of negative electrode and positive electrode were prepared.

The procedure for producing the negative electrode will be described.
90 parts by weight of carbon having an average particle size of 20 μm obtained by calcination in an inert gas stream and pulverization, and 10 parts by weight of vinylidene fluoride resin as a binder were dispersed in N-methylpyrrolidone. Next, this slurry was applied on both sides of a copper foil current collector having a thickness of 10 μm to prepare an electrode original plate having a thickness of 180 μm. A negative electrode was obtained by cutting the coated portion into 82 mm × 284 mm, leaving a non-coated portion as a part of this electrode original plate as a lead portion.

The procedure for producing the positive electrode will be described.
91 parts by weight of LiC ₀ O ₂ powder having an average particle diameter of 15 μm, 6 parts by weight of graphite as a conductive agent, and 3 parts by weight of vinylidene fluoride resin as a binder were dispersed in N-methylpyrrolidone. This slurry was applied to both sides of a 20 μm thick aluminum foil current collector to prepare an electrode original plate having a thickness of 150 μm. Next, as with the negative electrode,
It was cut to a size of 279 mm to obtain a positive electrode.

A laminated electrode body was prepared from the two kinds of electrodes thus obtained. That is, using 43 negative electrodes and 42 positive electrodes, the thickness between the electrodes is 38 μm and the size is 8 μm.
It was laminated via a 7 mm × 289 mm microporous polyethylene film, and an adhesive tape was wrapped around the periphery and fixed to obtain a laminated electrode body.

Next, referring to FIG.
Will be described with reference to. The lead portion 2 of the laminated electrode body 1 is connected to the electrode terminal 4 fixed to the upper armor 3 having a thickness of 1.5 mm. Next, the laminated electrode body 1 is inserted into the battery container 5 in which the side surface of the stainless steel plate having a thickness of 300 μm is laser-welded to the stainless steel frame having a thickness of 1 mm.
The upper armor 3 and the battery container 5 are laser-welded to produce a single battery. From the electrolyte injection port 6 of the battery case with a built-in electrode, an electrolyte solution in which LiPF6 was dissolved at a ratio of 1 mol / l was injected into a mixed solvent of propylene carbonate and diethyl carbonate, and the plug was closed. A single battery of Here, the design capacity of the unit cell is 34 Ah.

Next, referring to FIG.
Will be described with reference to. Seven unit cells 21 are stored in a polyethylene battery pack container 20 with a space of 2 mm. Next, the positive electrode terminal and the negative electrode terminal of each unit cell are connected by a lead wire and connected to the positive and negative assembled battery terminals 23 also attached to the polyethylene upper lid 22. The assembled battery container 20 and the upper lid 22 are joined together via an O-ring to form an assembled battery case, and the pressure is 0 from the fluid injection port 25 of the upper lid (using a valve such as used for automobile tires). Carbon dioxide gas was injected under pressure so that the pressure was ¹ to 1 kg / cm ² , and the lid was closed to obtain the assembled battery of the final form.

Second Embodiment Next, a second embodiment will be described with reference to FIG.
The same laminated electrode body as that used in Example 1 was used.

First, the procedure for producing a unit cell will be described. 1
A flexible bag-shaped battery case in which a laminated electrode body 1 and the electrode terminal 4 are welded to a heat-sealed aluminum foil of polyethylene laminate having a thickness of 00 μm, and the laminated film is heat-sealed into a bag shape. Make 10. After this, an electrolytic solution (the same as the one used in Example 1) is supplied from the electrolytic solution inlet 6 provided in a part of the bag.
After the injection, was sealed with a similar laminate film by heat sealing to obtain a desired flexible single battery.

The unit cell used in this example is not limited to the above unit cell as long as it has a flexible side surface, and unit cells of other structures can also be used.

Next, the procedure for producing the assembled battery will be described with reference to FIG. Each of the seven cells prepared above was attached by screwing the electrode terminals to the top plate, and each cell was placed in a room of the aluminum die-cast container with cooling fins on the outer circumference of the cell. It is housed, the top plate is screwed to the container, and an assembled battery case is manufactured in the same manner as in Example 1. Finally, as a pressurized fluid, nitrogen gas is injected under pressure (0.
1 to 1 kg / cm2) to obtain the final assembled battery.

Third Embodiment Next, a third embodiment will be described. The assembled battery was the same as that used in Example 2 except for the pressurized fluid. Here, methane monochloromonobromide (halide fire extinguishing agent) was injected under pressure as a pressurized fluid to obtain a final assembled battery.

As the pressurized fluid having a self-extinguishing function, extinguishing agents other than those in Example 3 can be used. For example, foam extinguishing agents in which air or carbon dioxide gas is wrapped in liquid foam, strengthening liquid in which potassium carbonate, etc. are dissolved in water, and extinguishing powdery solids containing sodium hydrogen carbonate, phosphates, etc. as main components. It is also possible to use the drug by mixing it with carbon dioxide gas or the like.

Comparative Example Next, a comparative example will be described with reference to FIG.

As shown in FIG. 5, an assembled battery case having a size in which seven single cells can be inserted adjacent to each other is formed by an angle and an outer frame, and seven single cells produced in Example 1 are adjacently arranged in the case. Inserted in. After this, pressurizing springs (plate thickness 0.5
mm, deployment dimension 87 mm x 289 mm SUS304-C
A side plate having a leaf spring bent at a curvature of R75) was attached to the SP, and an assembled battery was produced by applying a pressing force due to the strain of the spring to the electrode plate in the single cell.

At this time, as a result of actually measuring the pressing force due to the strain of the spring, it was confirmed that the load was about 50 kg.

Next, evaluation results of various characteristics of Examples 1 to 3 and Comparative Example will be described. That is,
The weights and volumes of the batteries of Examples 1 to 3 and the comparative example were measured, and the individual cells assembled in the assembled battery, and 7 cells were connected in series to obtain charge / discharge characteristics and cycle characteristics. evaluated.

The charge / discharge characteristic test and the cycle characteristic test were carried out by the following methods.

Charging / discharging characteristic test Charging condition: 23 ° C., constant current 34A × 3H, 4.2V constant voltage charging Discharging condition: 23 ° C., 34A constant current discharging

Cycle characteristic test Charging / discharging was repeated 100 times under the above charging / discharging conditions to measure the discharge capacity retention rate.

The results of the charge / discharge characteristic test and the cycle characteristic test are shown in Table 1.

[0040]

[Table 1]

As can be seen from Table 1, the battery size is
The comparative example has a size of 218 × 305 × 131 mm, while the examples 1 to 3 have a size of 168 × 305 × 131 m.
It is as small as m. Further, the weight of the battery pack is 13 kg in the comparative example, whereas it is as small as 9 kg in the first embodiment and 8 kg in the second and third embodiments.

As a result, the energy weight density of the assembled battery is
In contrast to the comparative example of 64.1 Wh / Kg, in Example 1 it was as large as 92.6 Wh / Kg, and in Example 2 and Example 3 it was as large as 104.1 Wh / Kg. In addition, the energy volume density of the assembled battery is also 95.6 Wh / l in the comparative example, whereas it is 124.1 W in the examples 1 to 3.
It is as large as h / l.

On the other hand, the cycle characteristics were 80% in the comparative example, whereas they were 80% in Examples 1 to 3, indicating no deterioration.

From the above, according to this example, it is possible to provide an assembled battery having a high volume energy density and a high weight energy density. Further, the cells can be uniformly pressed, and the cells can be pressed even if they are separated from each other. Further, the cycle characteristics of the assembled battery are the same as those of the conventional one. Further, it is possible to provide an assembled battery having a self-extinguishing function even if the battery is destroyed.

The present invention is not limited to the above-mentioned embodiments, and it goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

[0046]

As described above, according to the present invention,
An assembled battery having high volume energy density and high weight energy density can be provided. Further, the cells can be uniformly pressed, and the cells can be pressed even if they are separated from each other. Further, the cycle characteristics of the assembled battery can be the same as those of the conventional one. Further, it is possible to provide an assembled battery having a self-extinguishing function even if the battery is destroyed.

[Brief description of drawings]

FIG. 1 is an assembly configuration diagram showing an example of a unit cell used in an assembled battery structure of the present invention.

FIG. 2 is a configuration diagram showing an embodiment of the assembled battery structure of the present invention.

FIG. 3 is a configuration diagram showing another example of the unit cell used in the assembled battery structure of the present invention.

FIG. 4 is a configuration diagram showing an example of an assembled battery structure of the present invention.

FIG. 5 is a configuration diagram showing a comparative example of an assembled battery structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Multilayer electrode body 2 Lead part 3 Upper lid 4 Electrode terminal 5 Battery container 6 Electrolyte injection port 7 Adhesive tape 8 Safety valve 9 Insulating film

Claims (4)

[Claims] 1. A unit cell in which a laminated electrode body in which flat plate-shaped or sheet-shaped electrodes are laminated is hermetically accommodated in a battery container having at least one side surface flexible, and a plurality of laminated electrode bodies are laminated in a stacking direction. An assembled battery structure in which the assembled battery containers are stacked in parallel and housed in an assembled battery container, wherein the assembled battery container is hermetically sealed and pressurized with a nonflammable fluid. 2. The assembled battery structure according to claim 1, wherein the nonflammable fluid is a deoxidized gas. 3. The assembled battery structure according to claim 1, wherein the nonflammable fluid is a fire-extinguishing fluid that is a fire extinguishing agent. 4. The assembled battery structure according to claim 3, wherein the fire-extinguishing fluid is a liquid or a liquid in which solid particles are dispersed.