Truck & Off-Highway Engineering - August 2023 - 21

PROPULSION | MANUFACTURING FEATURE
Age-defying developments
Bosch researchers are developing solutions that will help prolong the
lifetime of PEM fuel cells, from its current 20,000 operating hours to
as many as 30,000 hours in the future. " A lot of the aging is related
to the catalyst particles, " said Thilo Lehre, project manager for fuelcell
research activities. " A lot of it is reversible. Some aging effect can
be healed, so we are investigating specific healing conditions that we
implement in our operation strategy. "
Electrochemical surface area is lost during operation because
platinum particles and carbon supports oxidize and degrade.
Platinum particles grow and catalyst layers become thinner, Lehre
explained. Bosch researchers are working on homogeneous mixing
of oxidation-stable catalysts with ionomers and defect-free coating
of catalyst layers to combat the degradation. Healing can occur by
removing oxide layers and adsorbed sulfonates from catalyst surfaces,
he said.
System-level measures involve avoiding voltage fluctuations to
enable steadier operation of the fuel cell at around 700-800 mV,
Lehre told Truck & Off-Highway Engineering. This is accomplished by
using a small lithium-ion " buffer battery " to level out load cycling.
" Hybridization of the powertrain helps to extend the lifetime of the
fuel cell quite a bit, " he said. " And if you can operate the fuel cell at
medium power, then the efficiency gets better, too. "
Strict governmental criteria are
hampering H2
production and
the establishment of global
supply chains in Germany and
the EU, said Bosch's board
chairman Dr. Stefan Hartung:
" The United States is showing
us how it should be done.
The Inflation Reduction
Act is heavily subsidizing
the resources for ramping
up the hydrogen
economy. "
Lehre expects the anti-aging measures necessary to
achieve a 30,000-hour lifetime to be implemented in
the next generation, in the 2026-27 timeframe.
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Truck & Off-Highway Engineering - August 2023

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