Patent Description:
The redox flow battery has been known widely. The redox flow battery is a rechargeable battery discharged and charged by valence change of ions in electrolyte. The conventional redox flow battery is of plant type.

In the plant-type redox flow battery, tanks storing electrolyte and a cell in which oxidation-reduction of ions in electrolyte is caused so as to be charged or discharged are arranged separately from each other (PTL <NUM>, for example). Another relevant arrangement is known from PTL <NUM>.

The plant-type redox flow battery requires assembly of the tanks and the cell for example at the site where the battery is to be installed. Construction work for example for installation of the plant-type redox flow battery is therefore complicated. Further, because the tanks and the cell for example of the plant-type redox flow battery are arranged separately from each other, the installation area occupied by the installed battery is large.

The present invention has been made in view of these problems of the conventional art. More specifically, an object of the invention is to provide a battery that can be installed easily and its installation area can be reduced.

A battery according to an embodiment of the present invention includes: a plurality of tanks storing electrolyte containing ions of which valence is changed; a cell configured to cause oxidation-reduction of the electrolyte so as to be charged or discharged; a pipe connecting the plurality of tanks and the cell; and a pump configured to circulate the electrolyte between the plurality of tanks and the cell through the pipe. The battery according to an embodiment of the present invention includes a container housing the plurality of tanks, the cell, the pipe, and the pump. The container has a bottom, a side, and a top.

According to the foregoing, the battery according to an aspect of the present invention can be installed easily and its installation area can be reduced.

Initially, features of an embodiment of the present invention are described one by one.

The above features facilitate maintenance of the cell and the pump.

In the following, embodiments of the present invention are detailed with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference characters. The following embodiments may optionally be combined at least partially.

In the following, an overview of a configuration of a battery in a first embodiment is described.

<FIG> is a schematic diagram showing the configuration of the battery in the first embodiment. As shown in <FIG>, the battery in the first embodiment includes a cell <NUM>, a tank <NUM>, a pipe <NUM>, a pump <NUM>, and a container <NUM> (see <FIG>). The battery in the first embodiment may further include a cooler <NUM> (see <FIG>). To the battery in the first embodiment, an AC-DC converter <NUM> and a control panel <NUM> are connected.

Cell <NUM> includes an electrode <NUM>. Electrode <NUM> includes a positive electrode 11a and a negative electrode 11b. For positive electrode 11a and negative electrode 11b, carbon felt is used, for example.

Cell <NUM> also includes a membrane <NUM>. Membrane <NUM> divides cell <NUM> into a positive electrode 11a side and a negative electrode 11b side. Membrane <NUM> is an ion-permeable membrane that does not pass metal ions of which valence is changed, but passes ions acting to keep the electrical neutrality of the electrolyte.

Electrolyte <NUM> is stored in cell <NUM>. Electrolyte <NUM> includes a positive electrode electrolyte 13a and a negative electrode electrolyte 13b. Positive electrode electrolyte 13a circulates in the positive electrode 11a side of cell <NUM>. Negative electrode electrolyte 13b circulates in the negative electrode 11b side of cell <NUM>.

Electrolyte <NUM> contains metal ions of which valence is changed. Metal ions of which valence is changed that are contained in positive electrode electrolyte 13a are tetravalent vanadium ions (V<NUM>+) for example. Metal ions of which valence changed that are contained in negative electrode electrolyte 13b are trivalent vanadium ions (V<NUM>+) for example.

Electrolyte <NUM> contains ions acting to keep the electrical neutrality of the electrolyte. Ions acting to keep the electrical neutrality of electrolyte <NUM> are hydrogen ions (H+) for example.

Tank <NUM> includes a plurality of tanks. For example, tank <NUM> includes a positive electrode tank 2a and a negative electrode tank 2b. Positive electrode tank 2a stores positive electrode electrolyte 13a. Negative electrode tank 2b stores negative electrode electrolyte 13b. Preferably, positive electrode tank 2a and negative electrode tank 2b are corrosion resistant against electrolyte <NUM>. For example, polyethylene, rubber, or the like is used for positive electrode tank 2a and negative electrode tank 2b.

Pipe <NUM> includes a first pipe 3a, a second pipe 3b, and a third pipe 3c. First pipe 3a couples cell <NUM> to tank 2a. Second pipe 3b couples cell <NUM> to pump <NUM>. Third pipe 3c couples tank <NUM> to pump <NUM>. Preferably, pipe <NUM> is corrosion resistant against electrolyte. For example, polyethylene or the like is used for pipe <NUM>.

Pump <NUM> circulates electrolyte <NUM> between cell <NUM> and tank <NUM> through pipe <NUM>. Pump <NUM> causes electrolyte <NUM> to circulate through cell <NUM>, first pipe 3a, tank <NUM>, third pipe 3c, and second pipe 3b in this order, for example. A circulation pump, for example, is used as pump <NUM>.

Cooler <NUM> is provided for cooling the electrolyte. Cooler <NUM> is mounted on second pipe 3b. The location where cooler <NUM> is disposed is not limited to this. Cooler <NUM> may alternatively be mounted on first pipe 3a or third pipe 3c, for example. Cooler <NUM> is a water-cooling or air-cooling type heat exchanger.

<FIG> is an external view of the battery in the first embodiment. As shown in <FIG>, container <NUM> has a bottom <NUM>, a side <NUM>, and a top <NUM>. Details of the structure of container <NUM> are described later herein.

Cell <NUM>, tank <NUM>, pipe <NUM>, pump <NUM>, and cooler <NUM> are housed in container <NUM>. Cell <NUM>, tank <NUM>, pipe <NUM>, pump <NUM>, and cooler <NUM> are arranged on bottom <NUM>. Details of the arrangement of cell <NUM>, tank <NUM>, pipe <NUM>, pump <NUM>, and cooler <NUM> on bottom <NUM> are described later herein.

Preferably, AC-DC converter <NUM> and control panel <NUM> are disposed outside container <NUM>. AC-DC converter <NUM> converts AC from a power generation station P into DC and supplies DC to the cell. AC-DC converter <NUM> converts DC from cell <NUM> into AC and supplies AC to a load L. Control panel <NUM> controls pump <NUM> and AC-DC converter <NUM> for example.

In the following, an internal arrangement of the battery in the first embodiment is described.

<FIG> is a top view showing the internal arrangement of the battery according to the invention.

As shown in <FIG>, bottom <NUM> has a longer side 51a and a shorter side 51b. In the following, the direction parallel to longer side 51a is referred to as longitudinal direction, the direction parallel to shorter side 51b is referred to as widthwise direction, and the direction perpendicular to longer side 51a and shorter side 51b is referred to as height direction.

Cell <NUM>, tank <NUM>, pipe <NUM>, and pump <NUM>, and cooler <NUM> are arranged on bottom <NUM>.

Positive electrode tank 2a and negative electrode tank 2b are arranged in the widthwise direction. Preferably, tank <NUM> is disposed to be spaced from at least one of side <NUM> and top <NUM>.

Preferably, tank <NUM> is disposed between cell <NUM> and cooler <NUM> in the longitudinal direction. Pump <NUM> is disposed in a peripheral region of cooler <NUM>. In this case, second pipe 3b extends between tank <NUM> and side <NUM>.

The arrangement of cell <NUM>, tank <NUM>, pump <NUM>, and cooler <NUM> is not limited to the above-described one. <FIG> is a top view showing an internal structure of a battery according to a modification of the first embodiment. As shown in <FIG>, cooler <NUM> and pump <NUM> may be arranged between cell <NUM> and tank <NUM> in the longitudinal direction. Alternatively, as shown in <FIG>, cell <NUM> may be arranged between tank <NUM> and cooler <NUM> in the longitudinal direction.

<FIG> is a side view of an internal structure of the battery in the first embodiment. As shown in <FIG>, a guide member 51c may be mounted on bottom <NUM>. Guide member 51c is disposed to extend from bottom <NUM> in the height direction. Guide member 51c is disposed at each of four corners of bottom <NUM>.

In the following, a structure of container <NUM> for the battery in the first embodiment is described.

As described above, container <NUM> has bottom <NUM>, side <NUM>, and top <NUM>. Side <NUM> and top <NUM> form a lid <NUM>. Lid <NUM> is coupled to bottom <NUM>.

Lid <NUM> and bottom <NUM> may be separable from each other. Lid <NUM> may be equipped with a lifting ring <NUM>. Preferably, lifting ring <NUM> is disposed in the vicinity of each of four corners of top <NUM>. In this case, a wire may be inserted through lifting ring <NUM> and pulled up with a crane or the like to separate lid <NUM> from bottom <NUM>.

Side <NUM> may be equipped with a door <NUM>. On door <NUM>, side <NUM> is openable and closable. Preferably, door <NUM> is disposed at a position corresponding to at least one of cell <NUM>, pump <NUM>, and cooler <NUM> in container <NUM>.

In the following, operations of the battery in the first embodiment are described.

First, a charging operation is described. Positive potential is supplied from power generation station P to positive electrode 11a through a transformation station C and AC-DC converter <NUM>. Accordingly, tetravalent vanadium ions contained in positive electrode electrolyte 13a are subjected to an oxidation reaction at positive electrode 11a. Namely, tetravalent vanadium ions contained in positive electrode electrolyte 13a are changed into pentavalent vanadium ions.

Pump <NUM> is activated to cause positive electrode electrolyte 13a containing a high content of tetravalent vanadium ions to be supplied from positive electrode tank 2a to positive electrode 11a of cell <NUM> through pipe <NUM>. Then, a similar oxidation reaction is repeated. Accordingly, the ratio of pentavalent vanadium ions contained in positive electrode electrolyte 13a is increased.

Negative potential is supplied from power generation station P to negative electrode 11b through AC-DC converter <NUM>. The negative potential causes trivalent vanadium ions contained in negative electrode electrolyte 13b to be subjected to a reduction reaction at negative electrode 11b. Namely, trivalent vanadium ions contained in negative electrode electrolyte 13b are changed into divalent vanadium ions.

Pump <NUM> is activated to cause negative electrode electrolyte 13b containing a high content of trivalent vanadium ions to be supplied from negative electrode tank 2b to negative electrode 11b of cell <NUM> through pipe <NUM>. Then, a similar reduction reaction is repeated. Accordingly, the ratio of divalent vanadium ions contained in negative electrode electrolyte 13b is increased.

As such oxidation-reduction reactions occur, hydrogen ions in positive electrode electrolyte 13a move in cell <NUM> from the positive electrode 11a side to the negative electrode 11b side through membrane <NUM>. Thus, the electrical neutrality of the electrolyte is maintained. In this way, electric energy is stored in electrolyte <NUM>.

Next, a discharging operation is described. In the positive electrode 11a side of cell <NUM>, pentavalent vanadium ions contained in positive electrode electrolyte 13a are changed back to tetravalent vanadium ions through reduction. On the other hand, in the negative electrode 11b side of cell <NUM>, divalent vanadium ions contained in negative electrode electrolyte 13b are changed back to trivalent vanadium ions through oxidation. Such oxidation-reduction reactions cause hydrogen ions contained in negative electrode electrolyte 13b to move in cell <NUM> from the negative electrode 11b side to the positive electrode 11a side through membrane <NUM>. Accordingly, electromotive force is generated between positive electrode 11a and negative electrode 11b. This electromotive force causes electric power to be supplied to load L through transformation station C and AC-DC converter <NUM>.

Pump <NUM> is activated to cause positive electrode electrolyte 13a containing a high content of pentavalent vanadium ions and negative electrode electrolyte 13b containing a high content of divalent vanadium ions to be supplied from tank <NUM> to cell <NUM> through pipe <NUM>. Then, a similar reaction is repeated. Accordingly, electric power is kept supplied to load L.

The oxidation-reduction reactions as described above cause temperature increase of the electrolyte. Such a temperature increase of the electrolyte is suppressed by cooling electrolyte <NUM> by means of cooler <NUM>.

In the following, advantageous effects of the battery in the first embodiment are described.

The conventional redox flow battery has tanks and a cell for example that are arranged separately from one another. For the conventional redox flow battery, therefore, the tanks and cell for example must be assembled at the site where the battery is to be installed. In other words, the installation work for the conventional redox flow battery is complicated.

In contrast, as to the battery in the first embodiment, cell <NUM>, tank <NUM>, pipe <NUM>, and pump <NUM> are housed in container <NUM>. Therefore, the battery in the first embodiment may only be assembled in a factory or the like and thereafter conveyed to the installation site so as to install the battery at the site. Namely, the battery in the first embodiment can be installed easily.

In the conventional redox flow battery, tanks <NUM> and cell <NUM> for example are arranged separately from one another, resulting in a large installation area. In contrast, as to the battery in the first embodiment, cell <NUM>, tanks <NUM>, pipe <NUM>, and pump <NUM> are housed in container <NUM>, and therefore, the installation area can be substantially identical to the size of container <NUM>. Namely, the battery in the first embodiment can be installed in a smaller area. As seen from the above, the battery in the first embodiment is easy to install and its installation area is small.

In the first embodiment, the dead space in the whole space within container <NUM> can be reduced by arranging, in container <NUM>, a plurality of tanks, e.g., positive electrode tank 2a and negative electrode tank 2b in the widthwise direction of container <NUM>. This arrangement enables further downsizing of container <NUM>. In other words, this arrangement enables a greater capacity of tank <NUM>.

In the first embodiment, maintenance of pipe <NUM> is facilitated by arranging tank <NUM> between cell <NUM> and cooler <NUM> in the longitudinal direction. Further, in the first embodiment, maintenance of cooler <NUM> and pump <NUM> is facilitated by arranging cooler <NUM> and pump <NUM> between cell <NUM> and tank <NUM> in the longitudinal direction. Furthermore, in the first embodiment, maintenance of pipe <NUM> is facilitated by arranging cell <NUM> between tank <NUM> and cooler <NUM> in the longitudinal direction.

In the first embodiment, if lid <NUM> is separable from bottom <NUM>, maintenance can be done easily at the installation site by hoisting lid <NUM> with a crane or the like. In this case, guide member 51c can be provided to prevent damage due to contact of lid <NUM> with cell <NUM> for example while lid <NUM> is hoisted.

In the first embodiment, each of cell <NUM> and pump <NUM> disposed in container <NUM> can be accessed from an openable/closable portion located on side <NUM> of container <NUM> and corresponding to cell <NUM> or pump <NUM>. Accordingly, maintenance is facilitated.

In the following, a structure of a battery in a second embodiment is described. Differences from the first embodiment are mainly described herein.

The battery in the second embodiment includes cell <NUM>, tank <NUM>, pipe <NUM>, pump <NUM>, container <NUM>, and cooler <NUM>, similarly to the battery in the first embodiment. Container <NUM> for the battery in the second embodiment, however, differs from the battery in the first embodiment in that container <NUM> has a hole <NUM>. The battery in the second embodiment also differs from the battery in the first embodiment in that the former battery further includes a valve <NUM>.

<FIG> is a top view of the battery in the second embodiment. As shown in <FIG>, container <NUM> for the battery in the second embodiment has hole <NUM>. Preferably, hole <NUM> is formed in top <NUM> of container <NUM>.

<FIG> is a cross-sectional view of a peripheral region of tank <NUM> of the battery in the second embodiment. As shown in <FIG>, the battery in the second embodiment includes valve <NUM>. Valve <NUM> is a pressure valve like water seal valve, for example. Valve <NUM> is configured to allow gas to flow from a valve inlet 21a to a valve outlet 21b and prevent gas from flowing from valve outlet 21b to valve inlet 21a. Valve <NUM> thus has valve inlet 21a and valve outlet 21b. Valve inlet 21a communicates with the inside of tank <NUM>. Valve inlet 21a may communicate with the inside of at least one of positive electrode tank 2a and negative electrode tank 2b. Valve outlet 21b communicates with hole <NUM>. Accordingly, valve outlet 21b communicates with the outside of container <NUM>.

Valve <NUM> includes a valve body 21c, an inlet-side pipe 21d, and an outlet-side pipe 21e. One end of inlet-side pipe 21d forms valve inlet 21a. One end of outlet-side pipe 21e forms valve outlet 21b. Valve body 21c contains a liquid. The liquid in valve body 21c is water, for example. The other end of inlet-side pipe 21d is immersed in the liquid in valve body 21c. The other end of outlet-side pipe 21e is not immersed in the liquid in valve body 21c. Valve <NUM> is configured in this way to allow gas to flow from valve inlet 21a to valve outlet 21b and prevent gas from flowing from valve outlet 21b to valve inlet 21a.

In the following, an operation of the battery in the second embodiment is described.

In the battery in the second embodiment, electrolyte <NUM> is stored and gas is also present in tank <NUM>. Increase of the temperature in tank <NUM> causes the gas in tank <NUM> to expand. As mentioned above, valve <NUM> allows gas to flow from valve inlet 21a to valve outlet 21b. Therefore, the gas expanded in tank <NUM> flows through valve <NUM> and hole <NUM> to be discharged to the outside of container <NUM>.

Meanwhile, valve <NUM> prevents gas from flowing from valve outlet 21b to valve inlet 21a as mentioned above. Therefore, undesired gas is not allowed to flow from the outside of container <NUM> into tank <NUM>.

In the following, advantageous effects of the battery in the second embodiment are described.

If tank <NUM> is not equipped with valve <NUM>, increase of the temperature in tank <NUM> causes increase of the pressure in tank <NUM>. Accordingly, tank <NUM> may be broken.

In the battery in the second embodiment, tank <NUM> is equipped with valve <NUM>. Further, valve outlet 21b of valve <NUM> communicates with hole <NUM> formed in container <NUM>. Thus, as the temperature in tank <NUM> increases, the gas in tank <NUM> is discharged to the outside of container <NUM>. Therefore, even when the temperature in tank <NUM> increases, increase of the pressure in tank <NUM> is suppressed. As a result, breakage of tank <NUM> is suppressed. Moreover, in the battery in the second embodiment, since valve outlet 21b communicates with the outside of container <NUM>, gas in tank <NUM> can be prevented from filling the inside of container <NUM>.

In the following, a structure of a battery in a third embodiment is described. Differences from the first embodiment are mainly described herein.

The battery in the third embodiment includes cell <NUM>, tank <NUM>, pipe <NUM>, pump <NUM>, container <NUM>, and cooler <NUM>, similarly to the battery in the first embodiment. Container <NUM> for the battery in the third embodiment, however, differs from the battery in the first embodiment in that container <NUM> has a hole <NUM> and a ventilator <NUM>. Further, the battery in the third embodiment differs from the battery in the first embodiment in that the former battery further includes a valve <NUM>. In order to prevent rainwater or the like from entering the inside of container <NUM>, a water cover or the like (not shown) may be disposed appropriately over hole <NUM>.

<FIG> is a top view of the battery in the third embodiment. <FIG> is a side view of the battery in the third embodiment. As shown in <FIG> and <FIG>, container <NUM> for the battery in the third embodiment has hole <NUM> and ventilator <NUM>. Ventilator <NUM> is a ventilating fan, for example. Preferably, hole <NUM> is formed in top <NUM> of container <NUM>. Preferably, ventilator <NUM> is disposed in side <NUM> of container <NUM>.

<FIG> is a cross-sectional view of a peripheral region of tank <NUM> of the battery in the first embodiment. As shown in <FIG>, tank <NUM> of the battery in the third embodiment includes valve <NUM>. Valve inlet 21a of valve <NUM> communicates with the inside of at least one of positive electrode tank 2a and negative electrode tank 2b. Valve outlet 21b of valve <NUM>, however, differs from that of the battery in the second embodiment in that valve outlet 21b does not communicate with hole <NUM>. Like the battery in the second embodiment, valve <NUM> may be any valve allowing gas to flow from valve inlet 21a to valve outlet 21b and preventing gas from flowing from valve outlet 21b to valve inlet 21a. Preferably, valve <NUM> is a pressure valve like water seal valve.

In the following, an operation of the battery in the third embodiment is described.

In the battery in the third embodiment, electrolyte <NUM> is stored and gas is also present in tank <NUM>. Increase of the temperature in tank <NUM> causes the gas in tank <NUM> to expand. As mentioned above, valve <NUM> allows gas to flow from valve inlet 21a to valve outlet 21b. Therefore, the gas expanded in tank <NUM> flows through valve <NUM> to be discharged to the outside of container <NUM>.

In the battery in the third embodiment, container <NUM> has hole <NUM> and ventilator <NUM>. Therefore, in container <NUM>, an airflow from hole <NUM> to the outside of container <NUM> through ventilator <NUM> is generated. As a result, the gas discharged from the inside of tank <NUM> to the inside of container <NUM> through valve <NUM> is conveyed to the outside of container <NUM>.

In the following, advantageous effects of the battery in the third embodiment are described.

If tank <NUM> does not have valve <NUM>, increase of the temperature in tank <NUM> causes increase of the pressure in tank <NUM>. Accordingly, tank <NUM> may be broken.

In the battery in the third embodiment, tank <NUM> has valve <NUM>. Further, container <NUM> has hole <NUM> and ventilator <NUM>. Accordingly, as the temperature in tank <NUM> increases, gas in tank <NUM> is discharged to the inside of container <NUM>, and the gas discharged to the inside of container <NUM> is discharged to the outside of container <NUM> through ventilator <NUM>. Therefore, even when the temperature in tank <NUM> increases, increase of the pressure in tank <NUM> is suppressed. As a result, breakage of tank <NUM> is prevented and the gas discharged from tank <NUM> is prevented from filling the inside of container <NUM>.

In the following, a structure of a battery in a fourth embodiment is described. Differences from the first embodiment are mainly described herein.

The battery in the fourth embodiment includes cell <NUM>, tank <NUM>, pipe <NUM>, pump <NUM>, container <NUM>, and cooler <NUM>, similarly to the battery in the first embodiment. The battery in the fourth embodiment, however, differs from the battery in the first embodiment in that the former battery includes an additional pipe <NUM>. Additional pipe <NUM> allows electrolyte <NUM> for the battery in the fourth embodiment to be supplied to an additional cell <NUM> and/or an additional tank <NUM> disposed outside the battery in the fourth embodiment.

<FIG> is a top view of an internal structure of the battery in the fourth embodiment. As shown in <FIG>, additional pipe <NUM> includes, for example, a first additional pipe 31a, a second additional pipe 31b, a third additional pipe 31c, and a fourth additional pipe 31d.

First additional pipe 31a branches from first pipe 3a toward the outside of container <NUM>. Specifically, one end of first additional pipe 31a is connected to first pipe 3a, and the other end of first additional pipe 31a is connected to side <NUM> of container <NUM>.

Second additional pipe 31b branches from second pipe 3b toward the outside of container <NUM>. Specifically, one end of second additional pipe 31b is connected to second pipe 3b, and the other end of second additional pipe 31b is connected to side <NUM> of container <NUM>.

Third additional pipe 31c branches from third pipe 3c toward the outside of container <NUM>. Specifically, one end of third additional pipe 31c is connected to third pipe 3c, and the other end of third additional pipe 31c is connected to side <NUM> of container <NUM>.

Fourth additional pipe 31d extends from tank <NUM> toward the outside of container <NUM>. Specifically, one end of fourth additional pipe 31d is connected to tank <NUM>. The other end of fourth additional pipe 31d is connected to side <NUM> of container <NUM>.

First additional pipe 31a and second additional pipe 31b form a pipe for additional cell. Third additional pipe 31c and fourth additional pipe 31d form a pipe for additional tank. The above-described configuration is an example of additional pipe <NUM>, and additional pipe <NUM> is not limited to them.

The battery in the fourth embodiment includes a valve <NUM>. Valve <NUM> is disposed at each of the other end of first additional pipe 31a, second additional pipe 31b, third additional pipe 31c, and fourth additional pipe 31d. Valve <NUM> is also disposed between tank <NUM> and a joint of third pipe 3c and third additional pipe 31c. The battery in the fourth embodiment may have an element (not shown) like a check valve defining a flow path appropriately, at each of a preceding location and a following location of the joint where pipe <NUM> is connected to additional pipe <NUM>.

In the following, an operation of the battery in the fourth embodiment is described.

First, a description is given of a case where the battery in the fourth embodiment is used solely. In this case, all valves <NUM> are closed. Therefore, in this case, the battery in the fourth embodiment operates similarly to the battery in the first embodiment.

Next, a description is given of a case where a cell is provided in addition to cell <NUM> of the battery in the fourth embodiment. In this case, respective valves <NUM> disposed on first additional pipe 31a and second additional pipe 31b are opened. Meanwhile, respective valves <NUM> disposed on third additional pipe 31c and fourth additional pipe 31d are closed.

<FIG> is a top view showing a state of connection of pipes <NUM> for additionally providing a cell <NUM> for the battery in the fourth embodiment. As shown in <FIG>, in the battery in the fourth embodiment, respective other ends of first additional pipe 31a and second additional pipe 31b are connected to additional cell <NUM>.

When connection is made in this way, electrolyte <NUM> in tank <NUM> of the battery in the fourth embodiment is supplied to both cell <NUM> and additional cell <NUM> of the battery in the fourth embodiment.

Next, a description is given of a case where a tank is provided in addition to tank <NUM> of the battery in the fourth embodiment. In this case, respective valves <NUM> disposed on first additional pipe 31a and second additional pipe 31b are closed. Meanwhile, valve <NUM> disposed between tank <NUM> and a joint of third pipe 3c and third additional pipe 31c may be closed to circulate electrolyte <NUM> serially between tank <NUM> and additional tank <NUM> (see <FIG>). Respective valves <NUM> disposed on third additional pipe 31c and fourth additional pipe 31d are opened.

<FIG> is a top view showing a state of connection of pipe <NUM> in a case where a tank is provided in addition to tank <NUM> in the battery in the fourth embodiment. As shown in <FIG>, in the battery in the fourth embodiment, respective other ends of third additional pipe 31c and fourth additional pipe 31d are connected to additional tank <NUM>.

When the connection is made in this way, both electrolyte <NUM> in tank <NUM> and electrolyte <NUM> in additional tank <NUM> of the battery in the fourth embodiment are supplied to cell <NUM>.

The above-described configuration of the pipes and valves and the way to connect them are given by way of example. The configuration of the pipes and valves and the way to connect them may be those that enable additional cell <NUM> and/or additional tank <NUM> to be provided.

In the following, advantageous effects of the fourth embodiment are described.

The battery in the fourth embodiment includes additional pipe <NUM>. Thus, electrolyte <NUM> of the battery in the fourth embodiment is supplied to additional cell <NUM> and/or additional tank <NUM>. Accordingly, regarding the battery in the fourth embodiment, the electric power available from the battery and/or the power capacity of the battery can be increased.

It should be construed that the embodiments disclosed herein are given by way of illustration in all respects, not by way of limitation. It is intended that the scope of the present invention is defined by claims, not by the description above, and encompasses all modifications and variations equivalent in meaning and scope to the claims.

Claim 1:
A battery comprising:
a plurality of tanks (<NUM>) storing electrolyte (<NUM>) containing ions of which valence is changed;
a cell (<NUM>) configured to cause oxidation-reduction of the electrolyte (<NUM>) so as to be charged or discharged;
a pipe (<NUM>) connecting the plurality of tanks (<NUM>) and the cell (<NUM>);
a pump (<NUM>) configured to circulate the electrolyte (<NUM>) between the plurality of tanks (<NUM>) and the cell (<NUM>) through the pipe (<NUM>); and
a container (<NUM>) having a bottom (<NUM>), a side (<NUM>), and a top (<NUM>) and housing the plurality of tanks (<NUM>), the cell (<NUM>), the pipe (<NUM>), and the pump (<NUM>),
wherein:
the container (<NUM>) has a widthwise direction and a longitudinal direction,
the bottom (<NUM>) has a longer side (51a) and a shorter side (51b), and the longer side (51a) and the shorter side (51b) are parallel to the longitudinal direction and the widthwise direction, respectively, and
the plurality of tanks (<NUM>) are arranged in the widthwise direction.