Abstract: A frame body for a redox flow battery is provided with a window. The expressions A>C, B>D, and (B/A)?0.2 are satisfied, where A represents the length of a long side of a rectangle that envelops the window, B represents the width of a horizontal frame corresponding to the long side, C represents the length of a short side of the rectangle, and D represents the width of a vertical frame corresponding to the short side.

Abstract: Provided are a battery cell that can be produced efficiently. A frame body of each cell frame of a battery cell includes an inner peripheral recessed portion formed by reducing a thickness of a peripheral portion that surrounds an entire perimeter of the penetrating window so that the peripheral portion has a smaller thickness than other portions of the frame body. A bipolar plate of the battery cell includes an outer peripheral engaging portion that engages with the inner peripheral recessed portion, the outer peripheral engaging portion being a portion having a particular width and extending throughout an entire outer periphery of the bipolar plate.

Abstract: The battery cell for a flow battery includes a cell frame including a frame including a through-window and a manifold serving as an electrolyte flow path, and a bipolar plate blocking the through-window; a positive electrode disposed on one surface side of the bipolar plate; and a negative electrode disposed on another surface side of the bipolar plate. In this battery cell, in the frame, a thickness of a portion in which the manifold is formed is defined as Ft; in the bipolar plate, a thickness of a portion blocking the through-window is defined as Bt; in the positive electrode, a thickness of a portion facing the bipolar plate is defined as Pt; in the negative electrode, a thickness of a portion facing the bipolar plate is defined as Nt; and these thicknesses satisfy Ft?4 mm, Bt?Ft?3.0 mm, Pt?1.5 mm, and Nt?1.5 mm.

Abstract: A cell frame for a redox flow battery comprises: a bipolar plate; and a frame body provided at an outer periphery of the bipolar plate, the frame body including a manifold which penetrates through front and back surfaces of the frame body and through which an electrolyte flows, and at least one slit being formed on the front surface of the frame body and forming a channel of the electrolyte between the manifold and the bipolar plate, a cross sectional shape of the slit, in a longitudinal direction of the slit, having a width w and a depth h, the width w and the depth h satisfying (A) w?3 mm and (B) 1/8<h/w<1.