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DBFC New DBFC fuel cells receive double voltage boost

| Author / Editor: Luke James / Johanna Erbacher

Engineers at the McKelvey School of Engineering at Washington University have developed high-power direct borohydride fuel cells (DBFCs) that reportedly operate at double the voltage of conventional hydrogen fuel cells.

The research team of Vijay Ramani (Washington University) focuses on challenges in DHFCs, such as the correct distribution of fuel and oxidant and the reduction of parasitic reactions that affect performance.
The research team of Vijay Ramani (Washington University) focuses on challenges in DHFCs, such as the correct distribution of fuel and oxidant and the reduction of parasitic reactions that affect performance.
(Source: gemeinfrei / Pexels )

Liquid-fuelled fuel cells are an attractive potential alternative to traditional hydrogen fuel cells because they eliminate the need to transport and store hydrogen. At a much lower cost, they can help to power drones, unmanned vehicles in harsh environments, and, engineers believe, electric aircraft. They could also be used as range extenders for current battery powered electric vehicles (EVs), advancing their adoption by making them a more viable alternative to petrol-powered motors.

Now, engineers at the McKelvey School of Engineering at Washington University have developed high-power direct borohydride fuel cells (DBFCs) that reportedly operate at double the voltage of conventional hydrogen fuel cells.

Addressing key challenges in DBFCs

The research, led by Vijay Ramani, has pioneered a reactant: Identifying an optimal range of flow rates, flow field architectures, and resistance times that enable high power operation. According to the team, this approach, which can be applied to other classes of liquid and liquid fuel cells, addresses key challenges in DHFCs such as proper fuel and oxidant distribution, and the mitigation of parasitic reactions that leech performance.

The team has also demonstrated a single-cell operating voltage of 1.4 or more, double that of conventional hydrogen fuel cells. This doubling of the voltage allows for smaller, lighter, and more efficient fuel cell designs, highly advantageous for assembling multiple fuel cells into a stack for use in commercial applications. “The reactant-transport engineering approach provides an elegant and facile way to significantly boost the performance of these fuel cells while still using existing components,” Ramani said in a statement. “By following our guidelines, even current, commercially deployed liquid fuel cells can see gains in performance.”

A figure showing the open circuit voltages of the representative DBFC performance in green and current density in brown. DBFCs with peak power density at a high voltage of above 1 V are the blue columns and those with peak power density at a low voltage below 1 V are black columns. The research team’s work is the yellow column.
A figure showing the open circuit voltages of the representative DBFC performance in green and current density in brown. DBFCs with peak power density at a high voltage of above 1 V are the blue columns and those with peak power density at a low voltage below 1 V are black columns. The research team’s work is the yellow column.
(Source: Vijay Ramani)

Eliminating parasitic side reactions

A major part of improving any existing fuel cell technology is to eliminate side reactions, or at least reduce them. These parasitic reactions are a drain on resources and lead to lower performance efficiency levels. Usually, eliminating or mitigating them involves the development of new catalysts, and these face challenges in terms of adoption and deployment.

“Fuel cell manufacturers are typically reluctant to spend significant capital or effort to adopt a new material,” said Shrihari Sankarasubramanian, a senior staff research scientist on Ramani’s team. “But achieving the same or better improvement with their existing hardware and components is a game changer.”

Hydrogen bubbles that form on the surface of the catalyst have been a problem for DBFCs, however, the team minimises them using an optimised flow field design. “With the development of this reactant-transport approach, we are on the path to scale-up and deployment,” says Zhongyang Wang, a former member of Ramani’s lab.

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