JP2917460B2 - Liquid fuel cell power generation control method and liquid fuel cell - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power generation control method and a liquid fuel cell for a liquid fuel cell that retains liquid fuel remaining in a liquid fuel chamber during non-power generation. .

[Related Art] Generally, a methanol-air fuel cell using anolyte (methanol or a mixture of methanol and an electrolyte) as a liquid fuel and using air as an oxidant gas is well known as a liquid fuel cell. For example, JP-A-61
JP-A-248366 shows an example of the structure of this type of liquid fuel cell. FIG. 3 (a) schematically shows an internal state of the liquid fuel cell disclosed in the publication in a non-power generation state. In this figure, the structure of a part (power generation element part) directly involved in power generation is shown in relatively detail for easy understanding, and the structure of a circulation path for supplying and discharging anolyte to and from the power generation element part is shown. Is represented by a diagram. In FIG. 1, reference numeral 10 denotes an insulating case, which is composed of a unipolar current collector holder 11 and a unit cell holder 12. 21 ... are a plurality of cells, each cell 21 ... is an electrolyte
A positive electrode 21b formed of a porous metal and a negative electrode 21c formed of the same porous metal are formed by polymerizing the positive electrodes 21b with the 21a interposed therebetween. Each of the cells 21 comprises a unit cell group 20 composed of monopolar current collectors 22 and 23 connected to an external output terminal (not shown) and bipolar plates or bipolar current collectors 24 connecting each cell in series. And each cell
21 are held by the cell holders 12. The positive electrodes 21b of each of the cells 21 are provided so as to face the air chambers 31 in which air taken in from the outside flows in a direction perpendicular to the plane of the drawing, and the negative electrodes 21c have an anolyte from bottom to top. It is provided so as to face the flowing anolyte chambers 41. The unipolar current collectors 22 and 23 and the bipolar current collectors 24 are formed with a plurality of grooves along the flow direction of air or anolyte so that air or anolyte can easily pass therethrough. In the conventional battery, the discharge common anolyte flow path 50 is a single cell group so that the anolyte can be discharged from each of the cells 21 through the discharge common anolyte flow path 50.
It is located above 20. The discharge common anolyte channel 50 is connected to an anolyte tank 52 via a connection pipe 51. Below the anolyte chambers 41 are formed anolyte supply manifolds 42 for supplying anolyte for each anolyte chamber 41. Each of the manifolds 42 is an anolyte supply located at substantially the same height as the discharge common anolyte flow path 50. The passage 40 is connected by branch pipes 43.
The anolyte supply passage 40 is connected to a circulation pump 54 via a connection pipe 53.

At the time of power generation of the battery, the anolyte stored in the anolyte tank 52 is replaced by the anolyte tank 52 → the connection pipe 53.
→ Anolyte supply passage 40 → Branch pipe 43… → Anolyte supply manifold 42… → Anolyte chamber 41… → Common discharge anolyte flow path 50 → Connecting pipe 51… → Supply to each cell 21… through the flow path of the anolyte tank 52 Is done. When the battery is not generating power, the circulation pump 54 stops, and the distribution of anolyte is as shown in the figure. The anolyte in the discharge common anolyte flow path 50 returns to the anolyte tank 52 by the action of gravity, and finally enters the branch pipes 43, the anolyte supply manifold 42, and the anolyte chamber 41, as shown. Anolyte remains. The discharge common anolyte channel 50 is provided with a gas opening 50a having an anolyte outflow prevention valve.

As described above, in this type of battery, the anolyte is left inside the anolyte chambers 41 when no power is generated, thereby preventing outside air from entering the chambers and preventing oxidative corrosion of the negative electrodes 21c by air. . In addition, the anolyte is not left in the common anolyte channel 50 for discharge, thereby preventing a liquid short circuit between adjacent unit cells.

[Problems to be Solved by the Invention] However, even when the anolyte in the discharge common anolyte flow path 50 is returned to the anolyte tank 52 during non-power generation as in a conventional liquid fuel cell, the anolyte is completely returned. Requires some time. Therefore, at the beginning of the non-power generation of the battery, it was not possible to reliably prevent the occurrence of a liquid short circuit between the cells 21.
The current flow caused by the initial liquid short circuit during non-power generation is the third
An arrow I shown in FIG. As described above, when a local current flows inside the battery at the beginning of non-power generation, the current causes a problem that the current collector and the negative electrode plate cause electrolytic corrosion.

Further, in the conventional battery, since the anolyte supply passage 40 and the common anolyte discharge passage 50 are disposed above the anolyte tank 52, the variation in the amount of anolyte circulated in each cell becomes large, and the total amount of anolyte circulated There is a problem that if the amount is small, a cell in which anolyte does not flow at all can be formed.

An object of the present invention is to provide a power generation control method capable of preventing generation of a local current in a battery, and a liquid fuel cell capable of implementing the method.

[Means for Solving the Problems] The present invention relates to a plurality of unit cells in which a positive electrode arranged in an oxidizing gas chamber and a negative electrode arranged in a liquid fuel chamber are polymerized so as to sandwich an electrolyte therebetween. One or more bipolar current collectors that connect the two cells in series by contacting the positive electrode of one of the two cells and the negative electrode of the other cell; and supplying liquid fuel to the plurality of cells. Or a liquid fuel cell including a common liquid fuel flow path commonly provided for a plurality of cells to perform discharge, and holding the liquid fuel in a state remaining in the liquid fuel chamber during non-power generation. Targets power generation control methods.

In the power generation control method of the present invention, at the time of power generation, the contact state between the bipolar current collector and the positive electrode and the negative electrode is maintained regardless of the temperature,
During non-power generation, the contact between the bipolar current collector and the positive electrode in contact with the bipolar current collector is released regardless of the temperature.

In the liquid fuel cell of the present invention, at least a plurality of cells and one or more bipolar current collectors are housed and held in an insulating case. The insulating case includes one or more connection units that are capable of expanding and contracting a plurality of case units each housing a plurality of unit cells one by one regardless of the temperature at which the plurality of case units are connected in series. One or more bipolar current collectors are fixed to a case unit to which the other cell is fixed so as to be in contact with the negative electrode of the other cell, and a portion that contacts the positive electrode of the one cell is connected. Located in the unit. Then, in a state where the connecting unit is extended during non-power generation, the contact between the bipolar current collector and the positive electrode of one of the unit cells is released.

The common liquid fuel flow path is constituted by a supply common liquid fuel passage for supplying liquid fuel to each unit cell of the unit cell group and a discharge common liquid fuel passage for discharging liquid fuel from each unit cell. preferable.

[Operation] As in the power generation control method of the liquid fuel cell of the present invention, the contact state between the bipolar current collector and the positive electrode and the negative electrode is maintained during power generation, and the bipolar current collector and the bipolar current collector are not generated during non-power generation. If you cancel the contact with the positive electrode that comes into contact with the body, the series connection between the bipolar current collector and the positive electrode is cut off during non-power generation,
No circuit is formed to short each cell. Therefore, if the power generation of the battery is controlled using the power generation control method of the present invention, a liquid short circuit does not occur even if liquid fuel remains in the common liquid fuel flow path during non-power generation.

In the liquid fuel cell of the present invention, since the connecting unit that connects the case units accommodating the respective cells is configured to be extendable and contractible, if the connecting unit is contracted during power generation, a stacked liquid fuel cell is formed as in the related art. It can be used, and the electric connection between the bipolar current collector and the positive electrode can be cut off by extending the connecting unit during non-power generation. Therefore, it is possible to obtain a liquid fuel cell that can perform the power generation control method of the liquid fuel cell with a simple configuration in which the connection unit expands and contracts.

When the common liquid fuel flow path is composed of a supply common liquid fuel path for supplying liquid fuel to each unit cell and a discharge common liquid fuel path for discharging liquid fuel from each unit cell, the liquid fuel with little variation in liquid fuel You can get a battery.

Embodiment An embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 (a) is a perspective view of the liquid fuel cell of the present invention during power generation, and FIG. 1 (b) is a cross-sectional view taken along line AA of FIG. 1 (a). FIG. 2A is a perspective view of the liquid fuel cell during non-power generation, and FIG. 2B is a cross-sectional view taken along the line BB of FIG. 2A. In these figures, the same parts as those of the conventional liquid fuel cell shown in FIG. 3 are denoted by the same reference numerals as those shown in FIG. 3, and the description is omitted. The insulating case 100 includes three case units 101 to 103 and two connecting units 104 for connecting these case units.
And 105. Each case unit 101 ~ 10
An anolyte discharge passage 101a communicating with an anolyte chamber (liquid fuel chamber) 41.
To 103a and anolyte supply passages 101b to 103b. And in the center of each case unit is a single cell
A unit cell fixing portion for fixing 21 and a current collector fixing portion for fixing current collectors (22, 23, 24) are provided. The case unit 103 further includes an air chamber 310a. The connection units 104 and 105 have a structure that expands and contracts in the laminating direction, and expands and contracts the air chambers 310b and 310c, the anolyte discharge passages 104a and 105a, and the anolyte supply passage 104b.
And 105b. In the present embodiment, the anolyte discharge passages 101a to 105a constitute a discharge common liquid fuel passage, and the anolyte supply passages 101b to 105b constitute a supply common liquid fuel passage.The portions constituting these passages are made of polypropylene. Have been. Polypropylene is an excellent material for integrally forming the passage and forming the connecting units 104 and 105 so as to be able to expand and contract in bellows. Of course, other materials can be adopted. The connection units 104 and 105 constitute a connection portion that connects the unit cell fixing portion and the bipolar current collector fixing portion.

In the figure, the anolyte pump 54 is an anolyte tank
Although schematically shown in FIG. 52, the connection state between the anolyte pump 54 and the supply common liquid fuel passage including the anolyte supply passages 101b to 105b is such that anolyte can be appropriately supplied to the supply common liquid fuel passage. It is.

Although not shown in FIGS. 1 and 2, a fastener is attached to the insulating case 100 in order to hold the connecting units 104 and 105 in a contracted state.

At the time of power generation, a fastener (not shown) is tightened to bring the bipolar current collector 24 into contact with the positive electrode 21b of the adjacent cell. Then, the anolyte pump 54 is driven to cause the anolyte to flow upward from below the anolyte chambers 41 to generate electric power.
When the anolyte is supplied to each of the anolyte chambers 41 from a common passage disposed below, the anolyte can be supplied to each of the anolyte chambers 41 in a well-balanced manner. In order to switch to the non-power generation state, the pump 54 is stopped. Thereafter, the fastener (not shown) is released. When the restraint is released, as shown in FIG. 2, the connecting units 104 and 105 are extended by the spring force or restoring force of the connecting units 104 and 105, and the connecting units 104 and 105 are fixed to the current collector fixing portions in the case units 102 and 103. The fixed bipolar current collector 24 is connected to another adjacent case unit 10.
Positive electrode of cell 21 fixed to cell fixing parts 1 and 102
Separated from 21b. As a result, even if the anolyte remains in the anolyte chambers 41 and the anolyte discharge passages 104a and 105a of the connection units 104 and 105 are wet with the anolyte, the bipolar current collector 24 and the positive electrode 21b are electrically connected. Therefore, a circuit for short-circuiting the cell is not formed.

In the above embodiment, the connecting unit (connecting portion) is constituted by a bellows tube made of plastic, but the connecting unit may have any structure as long as it can expand and contract by allowing inflow and outflow of anolyte. The connecting unit may be constituted by such an elastic member as described above.

Although the above embodiment is an example of a liquid fuel cell including three unit cells, the present invention is not limited to the embodiment, and may be applied to a liquid fuel cell including more unit cells. Of course, it can be applied.

[Effects of the Invention] According to the power generation control method and the liquid fuel cell of the present invention, the series contact between the bipolar current collector and the positive electrode of the unit cell can be released during non-power generation. When the liquid fuel is left in the liquid fuel chamber to prevent corrosion of the electric body and the negative electrode, even if adjacent liquid fuel chambers are connected to each other by the remaining liquid fuel, a short circuit that short-circuits the unit cells. No circuit is formed, and the occurrence of electrolytic corrosion of the bipolar current collector and the negative electrode can be prevented. Therefore, according to the present invention, the life of the liquid fuel cell can be extended.

Further, according to the liquid fuel cell of the present invention, the bipolar current collector can be separated from the positive electrode with a simple structure in which the connecting unit connecting the case units accommodating each unit cell of the insulating case is expanded and contracted. The short circuit can be quickly separated with a simple structure.

Further, when the common liquid fuel passage is constituted by a supply common liquid fuel passage for supplying the liquid fuel to each unit cell and a discharge common liquid fuel passage for discharging the liquid fuel from each unit cell, the dispersion of the liquid fuel is small. A liquid fuel cell can be obtained.

[Brief description of the drawings]

FIG. 1 (a) is a perspective view of the liquid fuel cell of the present invention during power generation, and FIG. 1 (b) is a cross-sectional view taken along line AA of FIG. 1 (a). FIG. 2 (a) is a perspective view of the liquid fuel cell of the present invention at the time of non-power generation, and FIG. 2 (b) is a sectional view taken along line BB of FIG. 2 (a). FIG. 3 (a) is a diagram schematically showing an internal state of a conventional liquid fuel cell in a non-power generation state, and FIG. 3 (b) is a diagram showing a non-power generation of the cell shown in FIG. 3 (a). FIG. 6 is a diagram showing a flow of current caused by a liquid short circuit at the beginning of time. 10, 100 ... insulating case, 21 ... cell, 21a ... electrolyte, 21b ... positive electrode, 21c ... negative electrode, 24 ... bipolar collector,
31,310a ～ 310c …… Air room, 41 …… Anolite room, 101 ～
103 case unit, 101a to 105a anolyte discharge passage, 101b to 105b anolyte supply passage, 104,10
5… Connecting unit, 52… Anolyte tank, 54 ……
Anolite pump.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01M 8/00-8/24

Claims (3)

(57) [Claims] 1. A plurality of cells formed by polymerizing a positive electrode disposed in an oxidizing gas chamber and a negative electrode disposed in a liquid fuel chamber with an electrolyte interposed therebetween, and one of two adjacent cells. One or more bipolar current collectors that connect the two cells in series by contacting the positive electrode of the cell and the negative electrode of the other cell; and supplying or discharging liquid fuel to the plurality of cells. A method for controlling power generation of a liquid fuel cell, comprising: a common liquid fuel flow path provided in common for a plurality of cells, wherein the liquid fuel remains in the liquid fuel chamber when power is not generated. Sometimes the contact state between the bipolar current collector and the positive electrode and the negative electrode is maintained irrespective of the temperature, and when the power is not generated, the bipolar current collector and the positive electrode contacting the bipolar current collector are independent of the temperature. Characterized by releasing contact Power generation control method of body fuel cell. 2. A plurality of cells formed by polymerizing a positive electrode disposed in an oxidizing gas chamber and a negative electrode disposed in a liquid fuel chamber with an electrolyte interposed therebetween, and one of two adjacent cells. One or more bipolar current collectors that connect the two cells in series by contacting the positive electrode of the cell and the negative electrode of the other cell; and supplying or discharging liquid fuel to the plurality of cells. A liquid fuel cell comprising: a common liquid fuel flow path provided in common for a plurality of cells; and holding the liquid fuel in a state where the liquid fuel remains in the liquid fuel chamber during non-power generation. A battery and the one or more bipolar current collectors are stored and held in an insulating case, and the insulating case includes a plurality of case units each storing and holding one of the plurality of cells, and the plurality of cases. Units in series The one or more bipolar current collectors are fixed such that the one or more bipolar current collectors are in contact with the negative electrode of the other one of the cells. A portion fixed to the case unit and in contact with the positive electrode of the one unit cell is located in the connection unit, and in a state where the connection unit is extended during non-power generation, the bipolar current collector and A liquid fuel cell, wherein contact with the positive electrode of the one cell is released. 3. The common liquid fuel passage includes a supply common liquid fuel passage for supplying the liquid fuel to each unit cell of the unit cell group and a discharge common liquid fuel for discharging the liquid fuel from each unit cell. The liquid fuel cell according to claim 2, comprising a passage.