Bipolar plate, cell frame, cell stack and redox-flow battery

A bipolar plate for a battery, the bipolar plate having a positive electrode disposed on a first surface side thereof and a negative electrode disposed on a second surface side thereof,

• wherein at least one of the first surface and the second surface is provided with a flow path through which an electrolyte flows;
• the flow path includes an introduction port for the electrolyte, a discharge port for the electrolyte, and a groove section which is located between the introduction port and the discharge port and guides the electrolyte to a predetermined route;
• the groove section includes a plurality of vertical groove sections which extend in a vertical direction and are arranged in parallel in a direction orthogonal to the vertical direction when the bipolar plate is placed at a predetermined position in the battery;
• an inter-groove distance between side edges of adjacent vertical groove sections is from more than 100% to 700% of a width of the vertical groove section;
• the flow path includes an introducing path and a discharging path which are not in communication with each other;
• the introducing path and the discharging path each include a comb-tooth-shaped path, the comb-tooth-shaped paths being arranged to face each other in an interlocking manner, and the comb-tooth-shaped paths are provided with the vertical groove sections;
• a length of the portion where the comb-tooth-shaped paths are interlocked with each other is 80% to 99% of a length of the vertical groove section;
• and
• the depth of the groove is 10% to 45% of the thickness of the bipolar plate.