Bipolar plate, redox flow battery, and method for producing bipolar plate
Provided are a bipolar plate that can decrease the internal resistance of a flow battery, a redox flow battery, and a method for producing a bipolar plate. A bipolar plate sandwiched between a positive electrode in which a positive electrode electrolyte flows and a negative electrode in which a negative electrode electrolyte flows includes a positive-electrode-side surface in which a flow channel having a plurality of grooves through which the positive electrode electrolyte flows is provided and a negative-electrode-side surface in which a flow channel having a plurality of grooves through which the negative electrode electrolyte flows is provided. Each of the flow channels includes an inflow channel through which the electrolyte flows into the electrode and an outflow channel through which the electrolyte flows out of the electrode, the inflow channel and the outflow channel are not in communication with each other and are independent from each other, and the grooves each have a wide portion inside the groove, the wide portion having a width larger than a width of an opening of the groove.
1. A bipolar plate sandwiched between a positive electrode in which a positive electrode electrolyte flows and a negative electrode in which a negative electrode electrolyte flows, comprising:
a positive-electrode-side surface in which a flow channel having a plurality of grooves through which the positive electrode electrolyte flows is provided and a negative-electrode-side surface in which a flow channel having a plurality of grooves through which the negative electrode electrolyte flows is provided,
wherein each of the flow channels includes an inflow channel through which the electrolyte flows into the electrode and an outflow channel through which the electrolyte flows out of the electrode,
the inflow channel and the outflow channel are not in communication with each other and are independent from each other,
the grooves each have a wide portion inside the groove, the wide portion having a width larger than a width of an opening of the groove, and
wherein the grooves each include a narrow portion that has a constant width from the opening toward a bottom of the groove and the wide portion that is directly connected to the narrow portion and has a constant width down to the bottom.
2. The bipolar plate according to claim 1 , wherein an inter-groove distance between side edges of the openings of the adjacent grooves is larger than the width of the opening.
3. The bipolar plate according to claim 1 , wherein, when the opening has a width x,
the grooves each have a cross-sectional area equal to or larger than 10 times x 2 .
4. The bipolar plate according to claim 1 , wherein the inflow channel and the outflow channel each have a comb-teeth-shaped region, and
the inflow channel and the outflow channel are arranged so that the comb-teeth-shaped regions oppose each other so as to be interdigitated.
5. A redox flow battery comprising the bipolar plate according to claim 1 .