Abstract: Provided is an electrolyte for a flow battery, the electrolyte being supplied to a flow battery, in which a total concentration of ions of elements of groups 1 to 8 and ions of elements of groups 13 to 16 in the fifth period of the periodic table, and ions of elements of groups 1, 2, and 4 to 8 and ions of elements of groups 13 to 15 in the sixth period of the periodic table, the ions being impurity element ions involved in generation of a gas containing elemental hydrogen, may be 610 mg/L or less and a concentration of vanadium ions may be 1 mol/L or more and 3 mol/L or less.

Abstract: A battery cell for use in a redox flow battery, the battery cell including an electrode, a membrane facing one of both surfaces of the electrode, and a bipolar plate facing the other surface of the electrode, wherein the bipolar plate includes, in a surface thereof facing the electrode, a flow channel for an electrolyte, the electrode is a porous body containing carbon materials, and a compressive strain in a thickness direction of the electrode when a compressive stress of 0.8 MPa is applied in the thickness direction of the electrode is 20% or more and 60% or less.

Abstract: Provided is an electrolyte for a flow battery, the electrolyte being supplied to a flow battery, in which a total concentration of ions of elements of groups 1 to 8 and ions of elements of groups 13 to 16 in the fifth period of the periodic table, and ions of elements of groups 1, 2, and 4 to 8 and ions of elements of groups 13 to 15 in the sixth period of the periodic table, the ions being impurity element ions involved in generation of a gas containing elemental hydrogen, may be 610 mg/L or less and a concentration of vanadium ions may be 1 mol/L or more and 3 mol/L or less.

Abstract: A battery cell for use in a redox flow battery, the battery cell including an electrode, a membrane facing one of both surfaces of the electrode, and a bipolar plate facing the other surface of the electrode, wherein the bipolar plate includes, in a surface thereof facing the electrode, a flow channel for an electrolyte, the electrode is a porous body containing carbon materials, and a compressive strain in a thickness direction of the electrode when a compressive stress of 0.8 MPa is applied in the thickness direction of the electrode is 20% or more and 60% or less.

Abstract: Provided is an electrolyte for a flow battery, the electrolyte being supplied to a flow battery, in which a total concentration of ions of elements of groups 1 to 8 and ions of elements of groups 13 to 16 in the fifth period of the periodic table, and ions of elements of groups 1, 2, and 4 to 8 and ions of elements of groups 13 to 15 in the sixth period of the periodic table, the ions being impurity element ions involved in generation of a gas containing elemental hydrogen, is 610 mg/L or less, a concentration of vanadium ions is 1 mol/L or more and 3 mol/L or less, a concentration of free sulfuric acid is 1 mol/L or more and 4 mol/L or less, a concentration of phosphoric acid is 1.0×10?4 mol/L or more and 7.1×10?1 mol/L or less, a concentration of ammonium is 20 mg/L or less, and a concentration of silicon is 40 mg/L or less.

Abstract: Provided is a redox flow battery in which damage is unlikely to occur in a membrane. A redox flow battery includes a pair of adjacent cell frames, each cell frame including a frame body in which a flow channel for an electrolyte is formed, and a bipolar plate disposed inside the frame body; a positive electrode and a negative electrode disposed so as to face each other between the bipolar plates of the pair of cell frames; a membrane interposed between the positive electrode and the negative electrode; a protection plate which covers the flow channel and presses edge portions of the positive electrode or the negative electrode toward the bipolar plate; and a membrane protection structure which prevents the membrane from being broken by contact between the protection plate and the membrane.

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: 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: 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: 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: Provided is an electrolyte for a flow battery, the electrolyte being supplied to a flow battery, in which a total concentration of ions of elements of groups 1 to 8 and ions of elements of groups 13 to 16 in the fifth period of the periodic table, and ions of elements of groups 1, 2, and 4 to 8 and ions of elements of groups 13 to 15 in the sixth period of the periodic table, the ions being impurity element ions involved in generation of a gas containing elemental hydrogen, is 610 mg/L or less, a concentration of vanadium ions is 1 mol/L or more and 3 mol/L or less, a concentration of free sulfuric acid is 1 mol/L or more and 4 mol/L or less, a concentration of phosphoric acid is 1.0×10?4 mol/L or more and 7.1×10?1 mol/L or less, a concentration of ammonium is 20 mg/L or less, and a concentration of silicon is 40 mg/L or less.

Abstract: Provided is an electrolyte in which a total concentration of ions of elements of groups 1 to 8 and ions of elements of groups 13 to 16 in the fifth period of the periodic table, and ions of elements of groups 1, 2, and 4 to 8 and ions of elements of groups 13 to 15 in the sixth period of the periodic table, the ions being additive element ions involved in gas generation, is more than 610 mg/L.

Abstract: Provided is an electrolyte flow battery system including a gas supply mechanism that always continuously supplies a flow gas containing an inert gas to a gas phase in a tank that stores an electrolyte. In the electrolyte, the total concentration of ions of elements in groups 1 to 8 and 13 to 16 in the fifth period and groups 1, 2, 4 to 8, and 13 to 15 in the sixth period of a periodic table is 2,500 mg/L or less. The generation rate of hydrogen is less than 95 cc/h/m2 when a charge and discharge test is performed while the electrolyte is circulated and supplied to an electrolyte flow battery. The flow rate of the flow gas is 1.0 L/min or more and 50 L/min or less.

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: 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: Provided is a redox flow battery in which damage is unlikely to occur in a membrane. A redox flow battery includes a pair of adjacent cell frames, each cell frame including a frame body in which a flow channel for an electrolyte is formed, and a bipolar plate disposed inside the frame body; a positive electrode and a negative electrode disposed so as to face each other between the bipolar plates of the pair of cell frames; a membrane interposed between the positive electrode and the negative electrode; a protection plate which covers the flow channel and presses edge portions of the positive electrode or the negative electrode toward the bipolar plate; and a membrane protection structure which prevents the membrane from being broken by contact between the protection plate and the membrane.

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.

Abstract: Provided are a redox flow battery having a low internal resistance, an electrode used in a redox flow battery, and an electrode characteristic evaluation method with which a characteristic of an electrode can be simply and accurately evaluated. The redox flow battery includes at least one pair of electrodes in a stacked manner, the electrodes including a positive electrode and a negative electrode to which an electrolyte is supplied and in which a battery reaction is performed.

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.

Abstract: An electrolyte for a redox flow battery has a total concentration of arsenic ions and antimony ions of 15 mass ppm or less. In an example of the electrolyte for a redox flow battery, preferably, the concentration of the arsenic ions is 10 mass ppm or less. In another example of the electrolyte for a redox flow battery, preferably, the concentration of the antimony ions is 10 mass ppm or less.