Battery cell, cell stack, and redox flow battery

A battery cell comprising:

• an electrode;
• a bipolar plate arranged opposing the electrode;
• a supply edge to which an electrolyte solution is supplied;
• a discharge edge from which the electrolyte solution is discharged, the supply edge and the discharge edge being in a plan view from a direction in which the electrode and the bipolar plate overlap each other;
• a frame member located around the bipolar plate and having on an inner periphery of the frame member;
• a supply-side straightening portion extending along the supply edge;
• and
• a discharge-side straightening portion extending along the discharge edge;
• and
• a plurality of meandering flow paths each of which has an introduction port that is in connection with the supply edge, and a discharge port that is in connection with the discharge edge, and is serially disposed from the introduction port to the discharge port, the plurality of meandering flow paths being arranged in parallel in a widthwise direction, each of the meandering flow paths having:
• an introduction-side section extending from the introduction port toward a discharge edge side, and having an end portion on the discharge edge side;
• a turn-back section that is turned back from the end portion on the discharge edge side of the introduction-side section toward a supply edge side, and has an end portion on the supply edge side;
• and
• a discharge-side section extending from the end portion on the supply edge side of the turn-back section toward the discharge edge side, and reaching the discharge port,
• wherein a length in a lengthwise direction of a region in which the introduction-side section, the turn-back section, and the discharge-side section are arranged in the widthwise direction is 100 mm or more and 2000 mm or less, and the lengthwise direction is a direction from the supply edge toward the discharge edge, and the widthwise direction is a direction parallel to the supply edge and the discharge edge.