CELL FRAME AND REDOX FLOW BATTERY

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.