Various examples are provided for operational control of fuel cells. In one example, among others, a system for controlling a fuel cell includes a stack temperature controller in cascade with a liquid level controller. The liquid level controller can provide a control output based at least in part upon an indication of a liquid level of a liquid fuel tank and a level reference. The stack temperature controller can provide a fan speed control output based at least in part upon an indication of a stack temperature of the fuel cell and the control output of the liquid level controller. In another example, a system for estimating methanol concentration of a fuel cell system includes a state observer that generates an estimate of the methanol concentration of fuel provided to a direct methanol fuel cell based upon a plurality of states of the fuel cell system.

A hybrid redox fuel cell system includes a hybrid redox fuel cell including an anode side through which a reductant is flowed and a cathode side through which liquid electrolyte is flowed, and a catalyst bed fluidly connected to the cathode side of the hybrid redox fuel cell, the catalyst bed including a substrate layer and a catalyst layer spiral wound into a jelly roll structure. Furthermore, the liquid electrolyte includes a metal ion at a higher oxidation state and the metal ion at a lower oxidation state, and power is generated at the hybrid redox fuel cell by way of reducing the metal ion from the higher oxidation state to the lower oxidation state at the cathode side while oxidizing the reductant at the anode side.

The present invention is directed to a fuel cell system with various features for optimal operations of an electronic device, a battery charger or a fuel refilling device. The fuel cell system includes an information storage device associated with the fuel supply, pump and/or refilling device. The information storage device can be any electronic storage device including, but not limited to, an EEPROM or a PLA. The information storage device can include encrypted information. The information storage device can include software code for confirming the identification of the cartridge before operation of the electronic device and/or refilling device. The information storage device can include instructions for a hot swap operation to shut down properly when the fuel supply is ejected while the electronic device is in operation. The present invention is also directed to system architecture for a fuel cell system that utilizes information storage devices. The system architecture may have flow regulators, which include a regulating valve.

The present invention relates to SiC nanostructures, including SiC nanopowder, SiC nanowires, and composites of SiC nanopowder and nanowires, which can be used as catalyst supports in membrane electrode assemblies and in fuel cells. The present invention also relates to composite catalyst supports comprising nanopowder and one or more inorganic nanowires for a membrane electrode assembly.

Methods for measuring and controlling the methanol concentration in a methanol fuel cell such as a direct methanol fuel cell or fuel cell stack are disclosed. Processors and memory storage containing programs which execute instructions to control the methanol concentration in the fuel cell or fuel cell stack are also disclosed.

Disclosed is a method for recovering the battery capacity of a vanadium redox flow battery, comprising: S100: determining the overall valence of vanadium ions in electrolyte reservoirs of the battery after the discharge capacity of the battery attenuates, and charging the battery; S200: adding a reducing agent to a positive electrolyte reservoir of the battery; S300: allowing self-circulation in the positive electrolyte reservoir of the battery, so as to complete a chemical reduction reaction; S400: determining the overall valence of the vanadium ions in the electrolyte reservoirs of the battery again, and determining the residue of the reducing agent; and/or S500: replenishing the reducing agent in the positive electrolyte reservoir of the battery, and repeating steps S300 to S400 until the mean value of the overall valence of the vanadium ions in the electrolyte reservoirs of the battery returns to 3.5. By means of using a liquid reducing agent, feeding is simplified, and the reaction rate of the reducing agent with a positive electrolyte having a high content of pentavalent vanadium is fast. The extent of the valence-decreasing reaction of the reducing agent and the residual amount of the reducing agent are strictly monitored, so that the risk of the performance of a stack being affected due to the residue of the reducing agent is reduced.