JPH04248274A - Layer-built cell - Google Patents

Abstract

PURPOSE:To laminate primary cells or secondary cells in series. CONSTITUTION:A bipolar plate 1 is composed of electrodes 2 and 3 arranged on both sides of a sheet-form or a plate-form conductive base material. Plural number of the bipolar plates 1 are laminated through diaphragms 8 which have the ion conductivity and/or the electrolyte holding property and frame members 4 to surround the peripheral surfaces of the diaphragms 8, between the bipolar plates, so as to form a laminated body 7. The layer-built cell is composed of such a laminated body 7. The electrodes 2 and 3 are made by holding a cell active material in the collective body of conductive fibers. A large current can be picked up. A light weight and a compact size can be realized, and the energy density can be also improved.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention relates to a stacked battery, and in particular,
The present invention relates to a stacked battery that can extract a large current because primary or secondary batteries can be stacked in series, can be made lighter and smaller, and can easily improve energy density.

0002

[Prior Art] Conventionally, as stacked batteries, there are zinc-chlorine batteries (28th Battery Symposium 3A14, 1987) and zinc-bromine batteries (31st Battery Symposium 3C01, 1990).
, redox flow battery (3C10, 1990)
Flow-type batteries such as these have been mainly developed. This is because flow batteries tend to have a stacked structure, similar to bipolar electrolyzers. In other words, non-flow type batteries (
As with the series connection of cells (secondary batteries), as they are repeatedly charged and discharged, the depth of charge of each cell becomes uneven, and the battery capacity decreases over time. For this reason, general lead batteries require an operation called equal charging to deal with this problem.

[0003] Non-flow type secondary batteries have these problems, but due to the recent demand for high output density, stacking of lead secondary batteries has been considered, and the following proposals have been made. is being done. JP-A-56-149776 "Lead-acid battery" (Bipolar plate for lead-acid batteries, etc.) JP-A-2-84265 "Polar plate for bipolar type lead-acid battery" (Active material coated plate) JP-A-2-158057 "Bipolar plate" ``Electrode substrate for lead-acid batteries'' (film-formed carbon plate) Utility Model Application No. 2-165562 ``Electrode plate for lead-acid batteries and its manufacturing method'' (lead-plated nonmetallic sheet)

0004

[Problem to be solved by the invention] However, currently,
There is no bipolar plate with sufficient durability that can replace lead plates, and lead plates also deform due to the difference in thermal expansion coefficient with the active material. Currently, it has not reached the stage of practical use.

That is, for example, by using a lead plate as a bipolar partition plate,
When lead oxide (mainly PbO2) was attached to this as a positive electrode active material, the change in size of the active material during charging and discharging caused the lead plate to deform and distort the entire battery. . In addition, lead plates made the batteries themselves extremely heavy. If you switch from a lead plate to a plate made of glassy carbon, etc., the battery will become lighter, but the plate and active material will separate due to changes in size as the active material charges and discharges, and the internal resistance of the battery will significantly increase. increase For this reason, the development of bipolar plates to replace lead plates was
This is considered an important requirement for the practical application of stacked lead-acid batteries.

The present invention solves the above conventional problems, has chemical durability, and does not become non-conductive or undergo shape deformation due to charge/discharge reactions (in the case of secondary batteries) or discharge reactions (in the case of primary batteries). The purpose of this invention is to provide a high-performance stacked battery using the configuration of bipolar plates and active materials.

[0007]

[Means for Solving the Problems] The laminated battery of the present invention includes a plurality of bipolar plates each having electrodes on both sides of a sheet-like or plate-like conductive base material, and between each bipolar plate there is an ionic conductivity and/or Alternatively, in a stacked battery comprising a laminate formed by laminating a diaphragm having an electrolyte retaining property and a frame material surrounding the outer peripheral surface of the diaphragm, the electrode has a battery active material supported on an aggregate of conductive fibers. It is characterized in that it is made of

The laminated battery of the present invention will be explained in detail below with reference to the drawings. FIG. 1 is a partially cutaway perspective view of a laminated battery according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view showing the laminated structure of this laminated battery.

In FIG. 2, a positive electrode 2 is provided on one surface of a conductive bipolar plate 1, and a negative electrode 3 is provided on the other surface. Note that, hereinafter, the positive electrode 2 and the negative electrode 3 may be referred to as electrodes 2 and 3. These electrodes 2 and 3 are in direct contact with the bipolar plate 1 and are electrically conductive. Further, the outer peripheries of the electrodes 2 and 3 are each surrounded by a non-conductive frame 4. Each frame 4 is provided with an electrolyte injection hole 5, and a stopper 6 is inserted into the injection hole 5.

A plurality of stacks 7 of the bipolar plates 1, electrodes 2, 3, and frame 4 are stacked with a diaphragm 8 interposed between each stack 7. At the top of this laminate in FIG. 2, a negative electrode 3, an end plate 9, and a current collecting copper plate 10 are installed.
At the bottom of the figure, a positive electrode 2, an end plate, and a current collecting copper plate are installed and stored in a battery case 11. 12,
13 is a battery terminal protruding from the end of the current collecting copper plate.

[0011] In the present invention, the electrode is an aggregate of conductive fibers supporting a battery active material. Here, examples of the conductive fibers include carbon fibers, metal fibers, thread-like or thin strip-like materials of metals or metal oxides, fibrous conductive plastics, and the like. In addition, as an aggregate of these conductive fibers, conductive fiber felt (non-woven fabric), cloth (woven fabric), conductive fibers intertwined, or conductive fibers arranged in whiskers on a conductive plate are used. Examples include those grown by attachment. Specifically, carbon fiber cloth or non-woven fabric, metal thread felt or cloth, carbon fiber is good for lead batteries, and carbon fiber is good for alkaline batteries and non-aqueous batteries.
Metal threads can also be used.

[0012] The bulk density (apparent specific gravity) of such an aggregate of conductive fibers is preferably 0.01 g/cm3 or more. That is, if the bulk density of the aggregate of conductive fibers is small, a sufficient contact area between the conductive fibers cannot be ensured, resulting in insufficient current collection efficiency. Therefore, this bulk density is 0.01 g/cm3 or more, especially 0.03 g/cm3 or more.
It is preferable to set it as cm3 or more.

On the other hand, there are no particular restrictions on the active material supported on such an aggregate of conductive fibers, and any active material for primary batteries or secondary batteries that has been practically used can be used. Can be done. In addition, aluminum can be used as the negative electrode active material, manganese dioxide can be used as the positive electrode active material for secondary batteries, magnesium can be used as the negative electrode active material for secondary batteries, and lead sulfate can be used as the bipolar active material for secondary batteries.

[0014] Examples of methods for supporting such an active material on the conductive fiber aggregate include the following methods. ■ Impregnation with a solution or suspension of active material. For example, in the case of a lithium battery, the assembly is impregnated with a solution in which lithium perchlorate (LiClO4) is dissolved or dispersed in propylene carbonate. ■Apply the active material paste. For example, lead paste (Pb-H2 SO4
) Lead dioxide paste (PbO2-H2SO4) or nickel dioxide paste (NiO2-NaOH, K
OH) to the aggregate. ■ Spray the active material paste. For example, a relatively low-viscosity paste of the above (1) is sprayed onto the aggregate. There is no particular limit to the amount of active material supported on the aggregate of conductive fibers, and it is determined appropriately depending on the purpose of use, etc., but in normal cases, the amount of active material supported on the aggregate of conductive fibers is set to 0. .01 to 5 g of active material/cm3 of aggregate is preferred.

The sheet-like or plate-like conductive base material of the bipolar plate is a conductive fiber aggregate that is stretchable or flexible and supports an active material, that is, absorbs deformation of the electrode, or It is important that the degree of thermal expansion is the same as that of the active material-supporting conductive fiber aggregate and the frame. Specifically, a carbon plate, a plastic plate, a metal plate, etc. can be used.

[0016] The frame is made of closed cell resin (lightweight)
It is preferable to use resin with high elasticity (high modulus of elasticity). In particular, when the base material of the bipolar plate or the conductive fiber of the battery is a metal with a large coefficient of thermal expansion, the frame is preferably a flexible silicone rubber sheet or the like. Further, when using an organic solvent-based electrolyte such as a lithium battery, it is preferable to use a fluororesin-based frame, especially a foamed body thereof.

As the diaphragm, glass mats, microporous polymer membranes, ion exchange membranes having a cation and/or anion exchange function, and especially for non-aqueous systems, fluorine-based ion exchange membranes are suitable. be.

[0018] In the present invention, it is important to install an aggregate of conductive fibers supporting an active material, which is an electrode, on the conductive base material of the bipolar plate in such a way that sufficient electrical contact can be maintained. be. For this purpose, treatments such as thermal fusion, adhesion with a conductive adhesive, and sintering are performed.

[0019] Furthermore, the electrodes of this bipolar plate include
It is important that the frame is fully seated. For this reason, the frame is also integrated by means such as heat fusion, adhesion, and sintering. This allows the electrolyte to be retained without leaking into adjacent cells (stack). This is extremely important in preventing liquid junctions between cells. In other words, a liquid junction causes an internal short circuit in a laminated battery, resulting in a drop in output and efficiency, but this method simply presses the frame onto the plate like a normal press-type bipolar electrolytic cell. In this case, liquid leakage between cells cannot be prevented.

[0020]

[Operation] In the laminated battery of the present invention, the battery is constructed such that an aggregate of conductive fibers supports an active material. In this way, since the active material is supported within the aggregate of conductive fibers, the volume change of the active material due to charging and discharging is absorbed by the conductive fibers, and the conductive base material and active material layer of the bipolar plate are There is no possibility that the internal resistance of the battery will increase due to separation. Therefore, it is possible to construct a stable and high-density output stacked battery by stacking a large number of stacks.

[0021]

[Examples] The present invention will be explained in more detail with reference to Examples below.

Examples 1 to 4 A laminated battery (three-layer laminated battery) of the present invention shown in FIGS. 1 and 2 was manufactured according to the configuration shown in Table 1 below. In addition, at both ends, copper plates were attached to the end plates (conductive sheets) using a conductive adhesive.

[0023]

[Table 1]

The obtained laminated battery was charged and discharged, and its characteristics were investigated. The results are shown in Table 2. From Table 2,
It is clear that the laminated battery of the present invention can extract a large current (output) at a higher voltage than conventional primary or secondary batteries. Incidentally, the current density in the electrode plates of conventional lead batteries is about 2 to 3 mA/cm2, and even in lithium secondary batteries, the upper limit is 0.1 to 1 mA/cm2.

[0025]

[Table 2]

[0026]

[Effects of the Invention] As detailed above, according to the stacked battery of the present invention, series stacking of lead-acid batteries, lithium secondary batteries, manganese secondary batteries, various alkaline secondary batteries, primary batteries, etc. can be easily realized. be done. As a result, a battery including a large-area electrode plate (in the present invention, a conductive fiber aggregate supporting an active material) can be constructed, and a large current can be extracted. Incidentally, in terms of current value, it is possible to extract more than 10 times as much current as, for example, a conventional lead or alkaline secondary battery, which is a so-called "drained" plate type battery.

Furthermore, as can be seen from the fact that the present invention has a structure similar to a bipolar electrolytic cell, the metal material for current collection can be greatly reduced compared to a monopolar cell or an electrolytic cell, so it is lightweight. , easy to downsize. That is, it is possible to easily achieve an improvement in energy density. for example,
In the case of lead-acid batteries, the improvement in energy density relative to volume and weight reaches 30 to 100%.

Furthermore, the size of a single electrode plate (in the present invention, a sheet-like or plate-like conductive base material) or an electrode plate can be increased to about several m2, similar to a bipolar electrolytic cell. As a full-scale large-capacity stacked battery, it can also be preferably used for load leveling.

The laminated battery of the present invention is extremely useful in fields where current primary batteries and secondary batteries are used, and the field in which these batteries are used is expected to expand by the present invention. Specifically, it is extremely useful in fields that require even higher output density (eg, electric vehicles, defense equipment), etc., such as electrically driven passenger cars, large backup power supplies, and load leveling batteries.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view showing one embodiment of a stacked battery of the present invention.

FIG. 2 is a field perspective view showing the stacked structure of the stacked battery.

[Explanation of symbols]

1 Bipolar plate 2 Positive electrode 3 Negative electrode 4 Frame body 8 Diaphragm

Claims (1)

[Claims] Claim 1: A plurality of bipolar plates each having electrodes on both sides of a sheet-like or plate-like conductive base material, and a diaphragm having ionic conductivity and/or electrolyte retention property between each bipolar plate. A stacked battery comprising a laminate stacked with a frame material surrounding the outer peripheral surface of the diaphragm, characterized in that the electrode is an aggregate of conductive fibers supporting a battery active material. Stacked battery.