Patent Application
20230238586
This disclosure relates to a bipolar storage battery.
A bipolar lead storage battery includes a bipolar electrode including a positive electrode, a negative electrode, and a substrate (a bipolar plate) in which the positive electrode is provided on one surface and the negative electrode is provided on the other surface. As illustrated in
In the bipolar lead storage battery as described above, the positive-electrode lead layer 220 might corrode due to sulfuric acid contained in an electrolytic solution, and a coating 260 of a corrosion product (lead oxide) might be generated on the surface of the positive-electrode lead layer 220 (see
Note that, here, a surface where the corrosion of the positive-electrode lead layer 220 (the positive electrode) due to sulfuric acid progresses because the electrolytic solution penetrates the interface between the positive-electrode lead layer 220 (the positive electrode) and the adhesive layer 240 due to the growth is hereinafter referred to as a “creepage surface” as appropriate. Further, a distance by which the corrosion progresses is referred to as a “creepage distance” as appropriate.
An object of the present invention is to provide a bipolar storage battery in which, even when growth occurs in a positive electrode due to corrosion caused by sulfuric acid contained in an electrolytic solution, the electrolytic solution has difficulty penetrating an interface between the positive electrode and an adhesive, and battery performance is hard to decrease.
A bipolar storage battery according to one aspect of the present invention is a bipolar storage battery including a bipolar electrode including a positive electrode, a negative electrode, and a bipolar plate in which the positive electrode is provided on one surface and the negative electrode is provided on the other surface, and the bipolar electrode includes a covering member configured to cover a peripheral part of an opposite surface of the positive electrode in close contact with the peripheral part, the opposite surface being opposite to a surface, of the positive electrode, bonded to the bipolar plate. By employing such a configuration, it is possible to secure a contact range between a positive-electrode lead layer and a positive active material layer and to prevent penetration of the electrolytic solution as much as possible.
The following describes embodiments of the present invention in detail with reference to the drawings. Note that the embodiments to be described below describe examples of the present invention. Further, various changes or improvements can be added to the present embodiments, and the embodiments with the changes or improvements can be also included in the present invention. The embodiments and their modifications are included in the scope of the invention and are also included in the invention described in the claims and in its equivalent range. Note that the following description deals with a lead storage battery as an example from among various storage batteries.
A structure of a bipolar lead storage battery 1 according to an embodiment of the present invention will be described with reference to
The bipolar lead storage battery 1 illustrated in
When the second plate units and the third plate units are alternately provided in a laminated manner between the first plate unit and the fourth plate unit, the bipolar lead storage battery 1 is formed having a generally rectangular solid shape, for example. The number of the second plate units to be provided and the number of the third plate units to be provided are set such that a power storage capacity of the bipolar lead storage battery 1 achieves a desired value.
A negative electrode terminal 107 is fixed to the first plate 11, and the negative electrode 110 fixed to the first plate 11 is electrically connected to the negative electrode terminal 107. A positive electrode terminal 108 is fixed to the fourth plate 14, and the positive electrode 120 fixed to the fourth plate 14 is electrically connected to the positive electrode terminal 108.
The first plate 11 to the fourth plate 14 are formed of well-known molding resin, for example. The first plate 11 to the fourth plate 14 are fixed to each other such that an inner part is sealed by an appropriate method to prevent an electrolytic solution from flowing outside.
The electrolytic layer 105 is constituted by a glass-fiber mat impregnated with an electrolytic solution containing sulfuric acid, for example.
The bipolar plate 111 is made of thermoplastic resin, for example. Examples of the thermoplastic resin to form the bipolar plate 111 include an acrylonitrile-butadiene-styrene copolymer (ABS resin) and polypropylene, for example. These thermoplastic resins are excellent in moldability and also excellent in sulfuric-acid resistance. Accordingly, even when the electrolytic solution contacts the bipolar plate 111, the bipolar plate 111 is hard to decompose, deteriorate, or corrode.
The positive electrode 120 includes a positive-electrode lead layer 101 as a positive-electrode current collector, the positive-electrode lead layer 101 being made of lead or lead alloy and disposed on the one surface of the bipolar plate 111, and a positive active material layer 103 disposed on the positive-electrode lead layer 101. The positive-electrode lead layer 101 is bonded to the one surface of the bipolar plate 111 via an adhesive 140 provided between the one surface of the bipolar plate 111 and the positive-electrode lead layer 101. Accordingly, on the one surface (a surface facing upward on the plane of paper in the figures such as
The negative electrode 110 includes a negative-electrode lead layer 102 as a negative-electrode current collector, the negative-electrode lead layer 102 being made of lead or lead alloy and disposed on the other surface of the bipolar plate 111, and a negative active material (NAM) layer 104 disposed on the negative-electrode lead layer 102. The negative-electrode lead layer 102 is bonded to the other surface of the bipolar plate 111 via the adhesive 140 provided between the other surface of the bipolar plate 111 and the negative-electrode lead layer 102. The positive electrode 120 is electrically connected to the negative electrode 110 by an appropriate method.
In the bipolar lead storage battery 1 according to the first embodiment with such a configuration, the bipolar electrode 130 is constituted by the bipolar plate 111, the positive-electrode lead layer 101, the positive active material layer 103, the negative-electrode lead layer 102, and the negative active material layer 104, as described above. A bipolar electrode is an electrode having functions both as a positive electrode and a negative electrode in a single electrode. The bipolar lead storage battery 1 according to the embodiment of the present invention has a battery configuration in which cell members are connected in series to each other by assembling the cell members such that the cell members are provided alternately in a laminated manner, each cell member being configured such that the electrolytic layer 105 is provided between the positive electrode 120 and the negative electrode 110.
Further, the bipolar lead storage battery 1 according to the first embodiment has a structure in which penetration of the electrolytic solution into an interface between the positive-electrode lead layer 101 and the adhesive 140 is restrained even when growth occurs in the positive-electrode lead layer 101 due to corrosion caused by sulfuric acid contained in the electrolytic solution. The following describes details of the structure in which the penetration of the electrolytic solution is restrained, with reference to
Note that, in the sectional views of the bipolar electrode 130, including
Accordingly, in the bipolar lead storage battery 100 according to this embodiment of the present invention, the covering member 150 may be provided to cover the peripheral part of the positive electrode 120, and, for example, the covering member 150 can be also provided to cover the peripheral part of the positive active material layer 103. Further, the negative electrode 110 formed on the other surface of the bipolar plate 111 is not illustrated.
The bipolar electrode 130 illustrated in
In the bipolar electrode 130 illustrated in
Further, in the bipolar lead storage battery 1 according to the first embodiment, the covering member 150 covers the peripheral part 120a in close contact with the peripheral part 120a on a surface (hereinafter, this surface is referred to as an opposite surface 120c) of the positive electrode 120, the surface being opposite from a surface, of the positive electrode 120, bonded to the bipolar plate 111.
One end part 150a side of a surface, of the covering member 150, facing the peripheral part 120a contacts the adhesive 140 provided in an extending manner in the vertical direction from the bipolar plate 111. That is, the covering member 150 is provided to cover the peripheral part 120a of the positive electrode 120.
At this time, it is preferable that the covering member 150 be disposed to press against the positive electrode 120. Because the covering member 150 makes close contact with the peripheral part 120a of the positive electrode 120, even when a coating 160 of a corrosion product (lead oxide) is generated on the surface of the positive electrode 120 as illustrated in
Accordingly, even when the growth occurs in the positive electrode 120 due to corrosion caused by sulfuric acid contained in the electrolytic solution, the positive electrode 120 is hard to be separated from the adhesive 140, and thereby the electrolytic solution is restrained from penetrating into the interface between the positive electrode 120 and the adhesive 140. Therefore, such a defect that battery performance decreases due to the occurrence of a short circuit or the like is hard to occur, a short circuit being caused when the corrosion caused by sulfuric acid reaches a back surface (a surface of the positive electrode 120, the surface facing the bipolar plate 111) of the positive electrode 120.
Here, the peripheral part 120a of the positive electrode 120 is an outer part of the opposite surface 120c. Accordingly, when the positive electrode 120 is regarded as a plane, the peripheral part 120a has a frame shape surrounding four sides of the positive electrode 120.
As for the covering member 150, when the covering member 150 covers even just part of the peripheral part 120a having a frame shape, the aforementioned effect is yielded. However, it is more preferable that the covering member 150 cover the entire of the peripheral part 120a having a frame shape, and this further successfully yields the aforementioned effect and makes it extremely hard to decrease the battery performance.
Here, the covering member 150 should have sulfuric-acid resistance by which the covering member 150 is hard to be corroded by sulfuric acid, and examples of a material for the covering member 150 include resin, metal (e.g., stainless steel), and ceramic having sulfuric-acid resistance, for example.
Further, in a case where the resin is selected as the material for the covering member 150, an acrylonitrile-butadiene-styrene copolymer (ABS resin), polypropylene, or the like can be used, for example. These thermoplastic resins are excellent in moldability and also excellent in sulfuric-acid resistance. Accordingly, even when the electrolytic solution contacts the covering member 150, the covering member 150 is hard to decompose, deteriorate, or corrode.
A region, of the positive electrode 120, making contact with the covering member 150 is a region including the peripheral part 120a and having a preset distance from the peripheral edge part 120b. More specifically, as illustrated in
That is, in consideration of the necessity of setting a large contact range between the positive-electrode lead layer 101 and the positive active material layer 103 constituting the positive electrode 120, it is necessary to set the distance L1 as short as possible, but when the distance L1 is too short, the penetration of the electrolytic solution is allowed, and the creepage distance is elongated. In view of this, the distance L1 is set to the range equal to or more than 4.6 mm but less than 10 mm.
Note that, in a case of the bipolar electrode 130 illustrated in
Further, as for the covering member 150, a distance L3 indicative of the thickness of the covering member 150 is formed to be equal to or more than 0.5 mm but equal to or less than 8.0 mm. Here, the reason why the thickness of the covering member 150 is set to such a range is as follows. In a case where the thickness of the covering member 150 is smaller than 0.5 mm, when the electrolytic solution penetrates into an interface between the opposite surface 120c of the positive electrode 120 and the covering member 150, there is a possibility that the covering member 150 rises. In the meantime, it is also conceivable that, when the thickness of the covering member 150 is thicker than 8.0 mm, this might affect a structure around the bipolar electrode 130.
By providing the covering member 150 in the region including the peripheral part 120a of the positive electrode 120 as such, even when the growth occurs, it is possible to prevent such a situation that the positive electrode 120 is separated from the covering member 150 by the electrolytic solution penetrating into the interface between the positive electrode 120 and the covering member 150.
Further, as a distance where the covering member 150 is provided, the distance L1 from the peripheral edge part 120b of the positive electrode 120 to the other end part 150b of the covering member 150 on the opposite surface 120c is set to be equal to or more than 4.6 mm but less than 10 mm. With this configuration, the electrolytic solution has difficulty penetrating the interface between the positive electrode 120 and the covering member 150. Thereby, the creepage distance is surely shortened so that it is possible to provide the bipolar lead storage battery 1 in which battery performance is hard to decrease.
Note that the distance of each part described with reference to
Because the covering member 150 has a predetermined thickness, even when growth occurs in the positive electrode 120 due to corrosion caused by sulfuric acid contained in the electrolytic solution, the covering member 150 is not stripped off. Thereby, the electrolytic solution is further restrained from penetrating into the interface between the positive electrode 120 and the covering member 150.
In the bipolar lead storage battery 1 according to the first embodiment as described so far, the covering member 150 is disposed directly on the peripheral part 120a of the positive electrode 120, as illustrated in
That is, an end part of the adhesive 140 disposed, on the peripheral edge part 120b side, between the one surface of the bipolar plate 111 and the positive electrode 120 extends to between the peripheral part 120a of the opposite surface 120c and the covering member 150 and bonds the peripheral part 120a to the covering member 150. With such a configuration, the covering member 150 is fixed to the bipolar plate 111 via the adhesive 140.
Note that, instead of such a configuration, the adhesive provided between the peripheral part 120a and the covering member 150 and the adhesive 140 provided between the one surface of the bipolar plate 111 and the positive electrode 120 may not be continuous with each other and may be provided separately.
By employing such a configuration, the covering member 150 more strongly makes close contact with the peripheral part 120a, and the coating 160 of the corrosion product is restrained still more from growing to the peripheral part 120a.
Next will be described a second embodiment of the present invention. Note that, in the second embodiment, the same constituent as a constituent described in the first embodiment above has a same reference sign as a reference sign used in the first embodiment, and a redundant description about the same constituent is omitted.
That is, as illustrated in
In the bipolar storage battery of the second embodiment, the covering member 150 is fixed to the frame 170. Accordingly, the covering member 150 is easily disposed to press against the positive electrode 120. By disposing the covering member 150 such that the covering member 150 presses against the positive electrode 120, the coating 160 of the corrosion product is restrained still more from growing to the peripheral part 120a.
The covering member 150 can be also fixed to the frame 170 by an adhesive. The adhesive by which the covering member 150 is fixed to the frame 170 and the adhesive 140 by which the bipolar plate 111 is fixed to the positive electrode 120 may be integrated with each other as illustrated in
Note that the frame 170 and the bipolar plate 111 may be an integrated member as illustrated in
Next will be described a third embodiment in the present invention. Note that, in the third embodiment, the same constituent as a constituent described in the first and second embodiments has a same reference sign as a reference sign used in the first and second embodiments described above, and a redundant description about the same constituent is omitted.
Accordingly, the covering member 150 is made of the same material as the frame 170. With such a configuration, the covering member 150 is more easily disposed to press against the positive electrode 120, as described above. Accordingly, by disposing the covering member 150 such that the covering member 150 presses against the positive electrode 120, the coating 160 of the corrosion product is restrained still more from growing to the peripheral part 120a.
Next will be described a fourth embodiment in the present invention. Note that, in the fourth embodiment, the same constituent as a constituent described in the first to third embodiments described above has a same reference sign as a reference sign used in the first to third embodiments, and a redundant description about the same constituent is omitted.
That is, when the adhesive is applied to the peripheral part 120a and is hardened to be turned into the covering member 150, it is possible to yield a similar effect to that of the covering member 150 formed of resin, metal, or ceramic having sulfuric-acid resistance.
In this case, the adhesive to form the covering member 150 may be integrated with the adhesive 140 by which the bipolar plate 111 is bonded to the positive electrode 120 as illustrated in
By employing such a configuration that the covering member 150 is formed of the adhesive 140, the covering member 150 more strongly makes close contact with the peripheral part 120a. The coating 160 of the corrosion product is restrained still more from growing to the peripheral part 120a.
Next will be described a fifth embodiment in the present invention. Note that, in the fifth embodiment, the same constituent as a constituent described in the first to fourth embodiment described above has a same reference sign as a reference sign used in the first to fourth embodiments, and a redundant description about the same constituent is omitted.
That is, when the adhesive is applied to the peripheral part 120a and is hardened to be turned into the covering member 150, it is possible to yield a similar effect to that of the covering member 150 formed of resin, metal, or ceramic having sulfuric-acid resistance.
Further, because the bipolar plate 111 includes the frame 170, the adhesive 140 forming the covering member 150 is also fixed to the frame 170. By employing such a configuration, the covering member 150 more strongly makes close contact with the peripheral part 120a, and the coating 160 of the corrosion product is restrained still more from growing to the peripheral part 120a.
Next will be described a sixth embodiment in the present invention. Note that, in the sixth embodiment, the same constituent as a constituent described in the first to fifth embodiments described above has a same reference sign as a reference sign used in the first to fifth embodiments, and a redundant description about the same constituent is omitted.
The modification of the first embodiment illustrated in
As such, in the bipolar lead storage battery according to the sixth embodiment, the covering member 150 is provided on the opposite surface 120c of the positive electrode 120 by the adhesive 140 and is fixed to the frame 170. Accordingly, the covering member 150 more strongly makes close contact with the peripheral part 120a, and the covering member 150 is easily disposed to press against the positive electrode 120. Further, the coating 160 of the corrosion product is restrained still more from growing to the peripheral part 120a.
The bipolar lead storage batteries according to the first to sixth embodiments were subjected to a cycle test in which application and non-application of potential are repeated alternatingly, continuously for four weeks under the environment of 60°. As a result, in any of the bipolar lead storage batteries according to the first to sixth embodiments, corrosion caused by sulfuric acid did not reach the back surface of the positive electrode 120, so that the battery performance did not decrease.
In the meantime, when a bipolar lead storage battery (a comparative example) having a similar configuration to the configuration illustrated in
With the bipolar lead storage battery according to each of the embodiments described above, even when growth occurs in the positive electrode due to corrosion caused by sulfuric acid contained in the electrolytic solution, the electrolytic solution is hard to penetrate into the interface between the positive electrode and the adhesive, and the battery performance is hard to decrease.
Note that, as the adhesive 140 used in the bipolar lead storage battery 1 according to the first to sixth embodiments, there is, for example, a hardened object of a reaction-curable adhesive configured to cure by a reaction between a base compound containing epoxy resin and a hardening agent containing an amine compound.
That is, the hardened object has such a property that the hardened object is hard to be corroded by sulfuric acid, and sulfuric acid is hard to penetrate the interface between the positive electrode 120 and the adhesive 140. Further, the hardened object is hard to decompose, deteriorate, or corrode even when the hardened object contacts the electrolytic solution.
Accordingly, because the positive electrode 120 strongly makes close contact with the adhesive 140, even when growth occurs in the positive electrode 120 due to corrosion caused by sulfuric acid contained in the electrolytic solution, the electrolytic solution is restrained from penetrating into the interface between the positive electrode 120 and the adhesive 140. Further, such a defect that the battery performance decreases due to the occurrence of a short circuit or the like is hard to occur, where the short circuit is caused when the corrosion caused by sulfuric acid reaches the surface, of the positive electrode 120, facing the bipolar plate 111.
The epoxy resin contained in the base compound may be, for example, at least either of bisphenol A epoxy resin and bisphenol F epoxy resin. As the epoxy resin, one type may be used alone, or two or more types may be used in combination.
The amine compound contained in the hardening agent may be, for example, an aliphatic polyamine compound, an alicyclic polyamine compound, or an aromatic polyamine compound. One of the amine compounds may be used alone, or two or more of the amine compounds may be used in combination.
Concrete examples of the aliphatic polyamine compound include aliphatic primary amine such as triethylenetetramine (C6H18N4), aliphatic secondary amine such as triethylenetetramine, and so on. Concrete examples of the alicyclic polyamine compound include alicyclic primary amine such as isophorone diamine (C10H22N2). Concrete examples of the aromatic polyamine compound include aromatic primary amine such as diaminodiphenylmethane (C13H14N2).
Note that, as described above, the description in each of the embodiments deals with the positive electrode as an example, but the structure described herein can be also employed for the negative electrode.
Further, as described above, the description in the embodiments of the present invention deals with the bipolar lead storage battery as an example. However, in a case where the above description also applies to other storage batteries using other metals (e.g., aluminum, copper, nickel), an alloy, or a conductive resin for a current collector instead of lead, naturally, the present invention does not preclude the application.
The following is a list of reference signs used in the drawings and in this specification.
1 bipolar lead storage battery
101 positive-electrode lead layer
102 negative-electrode lead layer
103 positive active material layer
104 negative active material layer
105 electrolytic layer
110 negative electrode
111 substrate (bipolar plate)
120 positive electrode
120
a peripheral part
120
b peripheral edge part
120
c opposite surface
130 bipolar electrode
140 adhesive
150 covering member
150
a one end part
150
b the other end part
160 coating
170 frame
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-165686 | Sep 2020 | JP | national |
| 2020-204824 | Dec 2020 | JP | national |
This application is a continuation of PCT/JP2021/033197, filed Sep. 9, 2021, which is incorporated herein in its entirety by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2021/033197 | Sep 2021 | US |
| Child | 18190671 | US |
