Patent Application
20170352894
The present invention relates to an electrolyte-circulating battery such as a redox flow battery. In particular, the present invention relates to an electrolyte-circulating battery in which a sealing structure of an electrolyte can be easily formed and which has a good assembling workability.
An example of large-capacity storage batteries that store the electric power derived from natural energy, for example, obtained by photovoltaic power generation or wind power generation, is an electrolyte-circulating battery such as a redox flow battery (RF battery). An RF battery is typically connected between a power generation unit (for example, a photovoltaic power generator, a wind power generator, or a typical power plant) and a load (for example, a power consumer) with an AC/DC converter therebetween, stores the electric power generated in the power generation unit by charging, and supplies the stored electric power to the load by discharging.
For example, as illustrated in the operation principle diagram of an RF battery of
The battery cell 100 is typically formed inside a structure referred to as a cell stack 200 illustrated in the lower drawing of
The flow of the electrolyte of each of the electrodes in the battery cell 100 is performed through liquid-supplying manifolds 131 and 132 and liquid-discharging manifolds 133 and 134 which are formed on the frame 122. The positive electrode electrolyte is supplied from the liquid-supplying manifolds 131 to the positive electrode 104 through guide grooves formed on one surface side (front side of the sheet) of the frame 122. As indicated by the arrows in the upper drawing of
For example, Patent Literature 1 describes that leakage of an electrolyte in a cell is prevented by providing an inner peripheral seal groove and an outer peripheral seal groove each having a rectangular cross-sectional shape on both surfaces of a frame body (frame) at positions facing each other, and arranging an inner peripheral seal and an outer peripheral seal in the inner peripheral seal groove and the outer peripheral seal groove, respectively. O-rings are used as the inner peripheral seal and the outer peripheral seal to come in contact with a membrane under pressure and to seal the electrolyte.
PTL 1: Japanese Unexamined Patent Application Publication No. 2002-367659
A sealing member such as an O-ring formed of an elastic material is soft and has a long string-like shape, and thus the shape of the O-ring is not easily determined. Accordingly, even when the O-ring is fitted in a seal groove, the O-ring may easily become detached from the seal groove. An example means for suppressing this detachment of the O-ring is to fix the O-ring to the seal groove with an adhesive. However, it is necessary to apply the adhesive onto the seal groove in advance, and production efficiency decreases with an increase in the number of production steps.
The present invention has been made in view of the circumstances described above. An object of the present invention is to provide an electrolyte-circulating battery in which a sealing structure of an electrolyte can be easily formed and which has good production efficiency.
An electrolyte-circulating battery according to an embodiment of the present invention includes a cell frame including a bipolar plate in contact with an electrode that forms a battery cell, and a frame that surrounds a peripheral edge of the bipolar plate; and a sealing member that is disposed on the frame and that prevents an electrolyte supplied to the battery cell from leaking out of the frame. The frame has a seal groove in which the sealing member is fitted. The seal groove includes a narrow section that causes the sealing member to elastically deform to prevent the sealing member from becoming detached from the seal groove. The narrow section has a width that is uniform in a depth direction of the seal groove.
According to the electrolyte-circulating battery, a sealing structure of an electrolyte can be easily formed, and good production efficiency is realized.
First, the content of embodiments of the present invention will be listed and described.
(1) An electrolyte-circulating battery according to an embodiment of the present invention includes a cell frame including a bipolar plate in contact with an electrode that forms a battery cell, and a frame that surrounds a peripheral edge of the bipolar plate; and a sealing member that is disposed on the frame and that prevents an electrolyte supplied to the battery cell from leaking out of the frame. The frame has a seal groove in which the sealing member is fitted. The seal groove includes a narrow section that causes the sealing member to elastically deform to prevent the sealing member from becoming detached from the seal groove. The narrow section has a width that is uniform in a depth direction of the seal groove.
According to the structure described above, detachment of the sealing member from the seal groove can be suppressed by simply fitting the sealing member in the narrow section of the seal groove. This is because since the seal groove includes the narrow section that causes the sealing member to elastically deform, the sealing member is locally compressed, and a frictional force can be applied to the compressed portion in a longitudinal direction and in a depth direction of the seal groove. Therefore, an adhesive is not necessary to fix the sealing member to the seal groove, and a step of applying an adhesive is unnecessary. The sealing structure of an electrolyte can be firmed without increasing the number of production steps. Accordingly, the structure described above realizes good production efficiency of the electrolyte-circulating battery.
In addition, since the width of the narrow section is uniform in the depth direction, production efficiency of the frame having the seal groove can be increased. This is because the seal groove including the narrow section can also be formed at the same time when the frame is produced, and thus the number of production steps is not increased. As in the structure described above, an example of the shape of a groove capable of suppressing detachment of the sealing member from the seal groove by simply fitting the sealing member in the seal groove is a trapezoidal shape or substantially trapezoidal shape whose width gradually increases in the depth direction, such as a dovetail groove. However, in the case of a frame having such a dovetail groove, the seal groove cannot be formed at the same time when the frame is produced, and thus it is necessary to separately perform grooving, resulting in an increase in the number of production steps. Although the frame is typically produced by, for example, injection molding, it is difficult to form a groove having a shape of a dovetail groove or the like by injection molding. This is because, in order to produce a frame having a dovetail groove, after a frame that does not have a dovetail groove is produced, it is necessary to form a groove by, for example, cutting so that the groove has a trapezoidal shape or a substantially trapezoidal shape.
(2) In an embodiment of the electrolyte-circulating battery, a width Wn (mm) of the narrow section may be 0.60 D or more and 0.97 D or less where D represents a diameter (mm) of the sealing member in a non-compressed state.
According to the structure described above, since the width Wn (mm) of the narrow section is 0.60 D or more, it is easy to prevent the sealing member from degrading in early use due to crushing or excessive compression. Since the width Wn (mm) of the narrow section is 0.97 D or less, detachment of the sealing member from the seal groove is easily prevented.
(3) In an embodiment of the electrolyte-circulating battery, the narrow sections may be disposed at intervals of 50 mm or more and 500 mm or less in a longitudinal direction of the seal groove.
According to the above structure, since a plurality of narrow sections are disposed at an interval of 50 mm or more, the interval of the narrow sections in the longitudinal direction of the seal groove is not excessively small. Therefore, the operation of fitting the sealing member in the seal groove is unlikely to be complicated. Since a plurality of narrow sections are disposed at an interval of 500 mm or less, detachment of the sealing member is easily prevented.
(4) In an embodiment of the electrolyte-circulating battery, the seal groove may include a curved section that curves in a longitudinal direction, and the narrow section may be disposed in the curved section.
According to the above structure, since the narrow section is disposed in the curved-line section (curved section) of the seal groove from which the sealing member becomes detached more easily than the straight-line section of the seal groove, detachment of the sealing member is effectively prevented.
Embodiments of the present invention will now be described with reference to the drawings. It is intended that the present invention is not limited to these examples but is defined by the claims described below, and that the scope of the present invention includes the meaning of equivalents of the claims and all modifications within the scope of the claims. Herein, a description will be made using a redox flow battery (RF battery) as an example of an electrolyte-circulating battery.
An RF battery according to Embodiment 1 includes, as in the existing RF battery described with reference to
[Cell Frame]
A cell frame 2 includes a bipolar plate 3 and a frame 4 that surrounds a peripheral edge of the bipolar plate 3. There are two types of the cell frame 2, namely, an intermediate cell frame disposed between adjacent battery cells 100 (
(Bipolar Plate)
The bipolar plate 3 partitions adjacent battery cells 100 (
(Frame)
The frame 4 forms a region functioning as a battery cell 100 (
<Seal Groove>
Sealing members 5 described below are fitted in the seal groove 48. The seal groove 48 is formed on both surfaces of the frame 4. Alternatively, the seal groove 48 is formed on one surface side (the front-surface side of the sheet of
The seal groove 48 is formed so as to have a ring shape along the outer shape (long dimensions of the pieces 41 to 43) of the frame 4. The seal groove 48 includes long straight-line sections 48L that are formed in the liquid supply-side piece 41 and the liquid discharge-side piece 42 and that are linear in the longitudinal direction, short straight-line sections 48S that are formed in the connection pieces 43 and that are linear in the longitudinal direction, and curved sections 48C that are formed at corners of the frame 4, that connect between a long straight-line section 48L and a short straight-line section 48S, and that curve in the longitudinal direction of the seal groove 48. The seal groove 48 includes narrow sections 49.
Each of the narrow sections 49 causes a sealing member 5 to elastically deform to prevent the sealing member 5 from becoming detached from the seal groove 48. The term “narrow section 49” refers to a section having a narrower groove width than other sections in the longitudinal direction of the seal groove 48. A width Wn of the narrow section 49 is less than a diameter D (mm) of the sealing member 5 in the non-compressed state. In other words, the width of each wide section other than the narrow sections 49 is equal to or more than the diameter D of the sealing member 5. Therefore, in the wide section, a space is formed between the sealing member 5 and the seal groove 48. The sealing member 5 can be easily fitted in the wide sections, and detachment of the sealing member 5 from the seal groove 48 can be suppressed by simply fitting the sealing member 5 in the narrow sections 49. This is because the narrow sections 49 can apply a suitable frictional force to the sealing member 5 in the longitudinal direction of the sealing member 5 and in the depth direction of the seal groove 48.
Each of the narrow sections 49 has a width Wn that is uniform in the depth direction of the seal groove 48 (
The width Wn (mm) of the narrow section 49 can be appropriately selected in accordance with the diameter D (mm) of the sealing member 5 in the non-compressed state so that the narrow section 49 does not cause the sealing member 5 to excessively elastically deform and does not cause the sealing member 5 to become detached. Herein, the term “width Wn” of the narrow section 49 refers to a width of a portion of the seal groove 48, the portion having the narrowest width. The width Wn of the narrow section 49 is preferably 0.60 D or more and 0.97 D or less though it depends on the material of the sealing member 5. When the width Wn of the narrow section 49 is 0.60 D or more, it is easy to prevent the sealing member 5 from degrading in early use due to crushing or excessive compression by the inner wall of the narrow section 49. When the width Wn of the narrow section 49 is 0.97 D or less, detachment of the sealing member 5 from the seal groove 48 is easily prevented. The width Wn of the narrow section 49 is more preferably 0.88 D or more and 0.97 D or less. The width Wn of the narrow section 49 satisfying 0.60 D or more and 0.97 D or less means that the compressibility of the sealing member 5 in the width direction is 3% or more and 40% or less. The compressibility in the width direction is defined as “{(diameter D of sealing member 5−width Wn of narrow section 49)/(diameter D of sealing member 5)×100}”.
A depth d (mm) of the seal groove 48 is preferably 0.6 D or more and 0.9 D or less though it depends on the material of the sealing member 5. When the depth d of the seal groove 48 is 0.6 D or more, detachment of the sealing member 5 from the seal groove 48 is easily prevented. In addition, since a region of the sealing member 5 exposed from the seal groove 48 is not excessively large, it is easy to prevent the sealing member 5 from being crushed by the adjacent cell frame or a sealing member provided on the adjacent cell frame (hereinafter, may be referred to as “adjacent member”). When the depth d of the seal groove 48 is 0.9 D or less, the region of the sealing member 5 exposed from the seal groove 48 can be appropriately ensured, and the sealing member 5 is easily and sufficiently compressed by the adjacent member. The depth d of the seal groove 48 is more preferably 0.7 D or more and 0.8 D or less. The depth d of the seal groove 48 satisfying 0.6 D or more and 0.9 D or less means that the compressibility of the sealing member 5 in the depth direction is 10% or more and 40% or less. The compressibility in the depth direction is defined as “{(diameter D of sealing member 5−depth d of seal groove 48)/(diameter D of sealing member 5)×100}”.
A total (Wn+d) of the width Wn of the narrow section 49 and the depth d of the seal groove 48 is preferably 1.2 D or more and 1.8 D or less. When the total (Wn+d) of the narrow section 49 is 1.2 D or more and 1.8 D or less, the sealing member 5 is sufficiently easily compressed, crushing of the sealing member 5 is easily prevented, and detachment of the sealing member 5 from the seal groove 48 is easily prevented. The total (Wn+d) of the narrow section 49 is more preferably 1.6 D or more and 1.7 D or less. Specifically, the total of the compressibility in the width direction and the compressibility in the depth direction preferably satisfies 20% or more and 80% or less. This total of the compressibility particularly preferably satisfies 40% or less.
A volume-occupying ratio of the sealing member 5 in the seal groove 48 is preferably 100% or less. This volume-occupying ratio is defined as (VS/VG)×100 where VG (mm3) represents the volume of the seal groove 48 and VS (mm3) represents the volume of the sealing member 5 in the non-compressed state. When the volume-occupying ratio is 100% or less, it is easy to prevent the sealing member 5 from being crushed, and it is possible to suppress the application of an excessive pressure onto the seal groove 48 when the sealing member 5 is compressed, and thus crushing of the seal groove 48 is also easily prevented. Since the volume-occupying ratio is 100% or less, when the sealing member 5 is compressed, a space is formed between the sealing member 5 and the seal groove 48 in a portion (wide section) other than the narrow sections 49. The volume-occupying ratio of the sealing member 5 in the seal groove 48 is preferably 50% or more. In this case, leakage of an electrolyte is more easily prevented over the entire perimeter of the frame 4. The volume-occupying ratio is particularly preferably 50% or more and 90% or less.
The narrow section 49 is formed in each of the long straight-line section 48L, the short straight-line section 48S, and the curved section 48C (
The interval of adjacent narrow sections 49 in the longitudinal direction of the seal groove 48 is determined so that, for example, detachment of the sealing member 5 can be prevented and the operation of fitting the sealing member 5 in the seal groove 48 is unlikely to be complicated. Specifically, the interval is preferably 50 mm or more and 500 mm or less, and more preferably 100 mm or more and 200 mm or less in the longitudinal direction of the seal groove 48.
The interval of adjacent narrow sections 49 may be uniform over the entire perimeter of the seal groove 48 or may be uniform in each of the liquid supply-side piece 41, the liquid discharge-side piece 42, and the connection pieces 43. In the latter case, as long as an interval L1 between narrow sections 49 in the long straight-line section 48L is uniform and an interval L2 between narrow sections 49 in the short straight-line section 48S is uniform, the interval L1 need not be the same as the interval L2 (
In this embodiment, the interval L1 between the narrow sections 49 in the long straight-line section 48L is a regular interval of 150 mm, and the interval L2 between narrow sections 49 in the short straight-line section 48S is a regular interval of 120 mm. The interval L3 is about 115 mm, and the interval L4 is about 90 mm.
The form of the narrow section 49 is not particularly limited as long as the width of the narrow section 49 is narrower than the width of other portions of the seal groove 48. In this embodiment, as illustrated in the circle shown by the one-dotted chain line in
The outline shape of each of the protruding pieces 49a can be appropriately selected. In this embodiment, the protruding piece 49a has an outline corresponding to a shape of an arc in which an apex is curved. Since the apex of the protruding piece 49a is curved, a frictional force can be applied to the sealing member 5 without damaging the sealing member 5. The bend radius of the protruding piece 49a can be appropriately selected. For example, the bend radius of the protruding piece 49a is preferably 1 mm or more and 50 mm or less, and particularly preferably 5 mm or more and 20 mm or less.
Examples of the material of the frame 4 include materials that satisfy acid resistance, electric insulation, and mechanical properties. Examples of such materials include fluororesins such as polytetrafluoroethylene, polypropylene resins, polyethylene resins, and vinyl chloride resins. In this embodiment, the frame 4 is formed of a rigid vinyl chloride resin.
[Sealing Member]
The sealing members 5 prevent an electrolyte supplied to the battery cell 100 (
For example, an O-ring is used as the sealing member 5. The cross-sectional shape of the sealing member 5 is a circular shape in the non-compressed state. As schematically illustrated in
Examples of the material of the sealing member 5 include elastic materials having good acid resistance. Suitable examples of the material of the sealing member 5 include rubbers such as ethylene-propylene-diene rubber (EPDM), fluororubber, and silicone rubber.
[Others]
The liquid supply-side piece 41 has liquid supply guide grooves 46 each extending between the corresponding liquid-supplying manifold 44 and the bipolar plate 3 to guide an electrolyte from the liquid-supplying manifold 44 to the bipolar plate 3. Similarly, the liquid discharge-side piece 42 has liquid discharge guide grooves 47 each extending between the corresponding liquid-discharging manifold 45 and the bipolar plate 3 to guide an electrolyte from the bipolar plate 3 to the liquid-discharging manifold 45. The liquid supply guide grooves 46 and the liquid discharge guide grooves 47 are covered with a plastic protective plate (not shown) when the stacked body is formed. With this structure, the electrolyte is allowed to flow between the liquid-supplying manifold 44 and the bipolar plate 3 and between the liquid-discharging manifold 45 and the bipolar plate 3 without leaking from the liquid supply guide groove 46 and the liquid discharge guide groove 47.
Manifold seal grooves 44a and 45a (
[Operation and Effect]
According to the RF battery of Embodiment 1, since the seal groove 48 includes the narrow section 49 that causes the sealing member 5 to elastically deform, detachment of the sealing member 5 from the seal groove 48 can be suppressed by simply fitting the sealing member 5 in the narrow section 49 of the seal groove 48. This is because a frictional force can be applied, in the longitudinal direction and in the depth direction of the seal groove 48, to a local position of the sealing member 5 deformed by the narrow section 49. Therefore, an adhesive is not necessary to fix the sealing member 5 to the seal groove 48, and a step of applying an adhesive is unnecessary. The sealing structure of an electrolyte can be formed without increasing the number of production steps. In addition, since the width of the narrow section 49 is uniform in the depth direction, production efficiency of the frame 4 having the seal groove 48 can be increased. This is because the seal groove 48 including the narrow section 49 can be formed at the same time when the frame 4 is produced, and thus the number of production steps is not increased. Accordingly, the structure described above realizes good production efficiency of the RF battery.
In Embodiment 2, as illustrated in
In Embodiment 3, as illustrated in
In Embodiment 4, as illustrated in
In Embodiment 5, as illustrated in
All the narrow sections 49 provided in the seal groove 48 may have the same shape, as described in Embodiment 1. Alternatively, the seal groove 48 may have narrow sections 49 having various shapes described in Embodiments 1 to 5 in combination.
The electrolyte-circulating battery according to an embodiment of the present invention can be suitably used in applications for the purpose of stabilizing variations in power output, storing generated power during oversupply, load leveling, and the like for new-energy power generation such as photovoltaic power generation or wind power generation. The electrolyte-circulating battery according to an embodiment of the present invention can also be additionally provided in a general power plant and suitably used as a large-capacity storage battery as a countermeasure against an instantaneous voltage drop/power failure and for the purpose of load leveling.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014-225656 | Nov 2014 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2015/079622 | 10/21/2015 | WO | 00 |
