University of California

Robert Boschgmbh

Adam Z Weber

Michael C Tucker

Paul Albertus

Edward Knudsen

Kyu Taek Cho

John Borland Kerr

Kyle D Clark

Qinggang He

Gi Suk Hwang

Zulima Martin

Peter Driscoll

Xiaobing Zhu

A flow battery system includes a first tank including a hydrogen reactant, a second tank including a bromine electrolyte, and at least one cell including a first electrolyte side operably connected to the first tank and a second electrolyte side operably connected to the second tank. The battery system further includes a direct connection line directly connecting the first tank and the second tank and configured such that the hydrogen reactant passes between the first tank and the second tank.

Hydrogen/bromine flow battery in which hydrogen is freely exchanged between two cell compartments

The Ce&#x2014;Hredox flow cell is optimized using commercially-available cell materials. Cell performance is found to be sensitive to the upper charge cutoff voltage, membrane boiling pretreatment, methanesulfonic-acid concentration, (+) electrode surface area and flow pattern, and operating temperature. Performance is relatively insensitive to membrane thickness, Cerium concentration, and all features of the (&#x2212;) electrode including hydrogen flow. Cell performance appears to be limited by mass transport and kinetics in the cerium (+) electrode. Maximum discharge power of 895 mW cmwas observed at 60&#xb0; C.; an energy efficiency of 90% was achieved at 50&#xb0; C. The Ce&#x2014;Hcell is promising for energy storage assuming one can optimize Ce reaction kinetics and electrolyte.

Optimization of the cerium-hydrogen redox flow cell

A flow battery system includes a first tank having a hydrogen reactant, a second tank having a bromine electrolyte, at least one cell including a hydrogen reactant side operably connected to the first tank through an &#xbe; feed and return system and a bromine electrolyte side operably connected to the second tank, and a crossover return system. The crossover return system includes a vessel operably connected to the &#xbe; feed and return system and configured to receive an effluent containing a first portion of the hydrogen reactant and a second portion of the bromine electrolyte, the vessel configured to separate the first portion from the second portion. A first return line returns the first portion of the hydrogen reactant to the first tank and a second return line returns the bromine electrolyte to the second tank.

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Water soluble catalysts, (M)meso-tetra(N-Methyl-4-Pyridyl)Porphinepentachloride (M=Fe, Co, Mn & Cu), have been incorporated into the polymer binder of oxygen reduction cathodes in membrane electrode assemblies used in PEM fuel cells and found to support encouragingly high current densities. The voltages achieved are low compared to commercial platinum catalysts but entirely consistent with the behavior observed in electroanalytical measurements of the homogeneous catalysts. A model of the dynamics of the electrode action has been developed and validated and this allows the MEA electrodes to be optimized for any chemistry that has been demonstrated in solution. It has been shown that improvements to the performance will come from modifications to the structure of the catalyst combined with optimization of the electrode structure and a well-founded pathway to practical non-platinum group metal catalysts exists.

Membrane-electrode structures for molecular catalysts for use in fuel cells and other electrochemical devices

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Pleasant Hill, CA, United States of America

Adam Z Weber