A redox flow battery system with a redox flow battery includes a redox flow cell, and a supply/storage system external of the redox flow cell. The supply/storage system includes first and second electrolytes for circulation through the redox flow cell. At least the first electrolyte is a liquid electrolyte that has electrochemically active species with multiple, reversible oxidation states. A secondary cell is fluidly connected with the first electrolyte and is operable to monitor concentration of one or more of the electrochemically active species. The secondary cell includes a counter electrode, a working microelectrode, and an ionically conductive path formed by the first electrolyte between the counter electrode and the working microelectrode.

A hydrogen leakage detection system for detecting a hydrogen leakage in a fuel cell system includes: an outer shell configured to accommodate a hydrogen flow section; a hydrogen sensor; and a porous sheet disposed to delimit at least a part of a space within the outer shell and allowing permeation of hydrogen through the porous sheet in a thickness direction thereof. The hydrogen flow section is disposed in a region below the porous sheet, and the hydrogen sensor is disposed in a region above the porous sheet.

A fuel cell system includes a first ion exchanger, a first fuel cell stack and a second fuel cell stack, a first temperature acquisition part and a second temperature acquisition part, a first power generation time acquisition part and a second power generation time acquisition part, a supply path, an ion concentration estimation part that estimates ion concentration of a refrigerant on the basis of the ion concentration estimated by the ion concentration estimation part, a determination part that determines an exchange timing of the first ion exchanger on the basis of the ion concentration estimated by the ion concentration estimation part, and a control part, and a first refrigerant flow path and a second refrigerant flow path are provided in series or in parallel.

A service providing mobile unit 1 comprised of a frame 2 forming a ring shape about a horizontal axis, movement-use wheels 4, 5 attached to the bottom part of the frame 2, a hydrogen storage tank insert pan 10 formed inside the frame 2, and a fuel cell 40 arranged inside the frame 2. Hydrogen is supplied to the fuel cell 40 from a replaceable hydrogen storage tank 20 inserted into the hydrogen storage tank insert part 10. A service providing space 3 having a ring-shaped inner circumference surface of the frame 2 as its outer edges is formed by the frame 2, and power can be supplied from the fuel cell 40 to a service providing unit installed inside the service providing space 3.

A hydrogen storage apparatus of a vehicle driven by a fuel cell comprising hydrogen storage tank holding apparatuses 8, 9 having pluralities of hydrogen storage tank insert parts 10. When the replaceable hydrogen storage tank 20 is inserted into the hydrogen storage tank insert part 10, the hydrogen outflow part 28 of the hydrogen storage tank 20 is coupled with the hydrogen inflow part 23 connected to the fuel cell 40. The grippable handle 24 is formed at the end portion of the hydrogen storage tank 20. A work of inserting the hydrogen storage tank 20 into the hydrogen storage tank insert part 10 and a work of coupling the hydrogen inflow part 23 and the hydrogen outflow part 28 is performed by gripping the handle 24.

A hydrogen storage apparatus of a vehicle driven by a fuel cell comprising hydrogen storage tank holding apparatuses 8, 9 having pluralities of hydrogen storage tank insert parts 10. When the replaceable hydrogen storage tank 20 is inserted into the hydrogen storage tank insert part 10, the hydrogen outflow part 28 of the hydrogen storage tank 20 is coupled with the hydrogen inflow part 23 connected to the fuel cell 40. The grippable handle 24 is formed at the end portion of the hydrogen storage tank 20. A work of inserting the hydrogen storage tank 20 into the hydrogen storage tank insert part 10 and a work of coupling the hydrogen inflow part 23 and the hydrogen outflow part 28 is performed by gripping the handle 24.

A service providing mobile unit comprising the frame 2, movement-use wheels 4, 5 provided at the bottom part of the frame 2, hydrogen storage tank insert parts 10 formed inside the frame 2, and the fuel cell 40 arranged in the frame 2. A service for supplying hydrogen to the fuel cell 40 from the hydrogen storage tank 20 inserted in the hydrogen storage tank insert part 10, a service for lending out the hydrogen storage tank 20 inserted in the hydrogen storage tank insert part 10, a service for returning a used hydrogen storage tank 20 to the hydrogen storage tank insert part 10, and a service for storing the hydrogen storage tank 20 inserted into the hydrogen storage tank insert part 10 are provided.

A service providing mobile unit comprising the frame 2, movement-use wheels 4, 5 provided at the bottom part of the frame 2, hydrogen storage tank insert parts 10 formed inside the frame 2, and the fuel cell 40 arranged in the frame 2. A service for supplying hydrogen to the fuel cell 40 from the hydrogen storage tank 20 inserted in the hydrogen storage tank insert part 10, a service for lending out the hydrogen storage tank 20 inserted in the hydrogen storage tank insert part 10, a service for returning a used hydrogen storage tank 20 to the hydrogen storage tank insert part 10, and a service for storing the hydrogen storage tank 20 inserted into the hydrogen storage tank insert part 10 are provided.

The control method for a flow battery includes acquiring a current electrolyte capacity decay rate of the flow battery; comparing the current electrolyte capacity decay rate with a first preset decay rate and a second preset decay rate; when the current electrolyte capacity decay rate is greater than the first preset decay rate and less than the second preset decay rate, adjusting a liquid level of positive electrolyte and a liquid level of negative electrolyte, such that a difference between these two liquid levels is less than a preset value, a ratio of the total amount of vanadium in the positive electrolyte to the total amount of vanadium in the negative electrolyte remains in a first preset ratio range, or a ratio of a vanadium ion concentration in the positive electrolyte to a vanadium ion concentration in the negative electrolyte remains in a second preset ratio range.

The control method for a flow battery includes acquiring a current electrolyte capacity decay rate of the flow battery; comparing the current electrolyte capacity decay rate with a first preset decay rate and a second preset decay rate; when the current electrolyte capacity decay rate is greater than the first preset decay rate and less than the second preset decay rate, adjusting a liquid level of positive electrolyte and a liquid level of negative electrolyte, such that a difference between these two liquid levels is less than a preset value, a ratio of the total amount of vanadium in the positive electrolyte to the total amount of vanadium in the negative electrolyte remains in a first preset ratio range, or a ratio of a vanadium ion concentration in the positive electrolyte to a vanadium ion concentration in the negative electrolyte remains in a second preset ratio range.