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Lawrence, KS, United States

Tucker M.C.,Lawrence Berkeley National Laboratory | Cho K.T.,Northern Illinois University | Weber A.Z.,Lawrence Berkeley National Laboratory | Lin G.,TVN Systems, Inc. | Van Nguyen T.,University of Kansas
Journal of Applied Electrochemistry | Year: 2015

The Br2/H2 redox flow cell shows promise as a high-power, low-cost energy storage device. The effect of various aspects of material selection, processing, and assembly of electrodes on the operation, performance, and efficiency of the system is determined. In particular, (+) electrode thickness, cell compression, hydrogen pressure, and (−) electrode architecture are investigated. Increasing hydrogen pressure and depositing the (−) catalyst layer on the membrane instead of on the carbon paper backing layers have a large positive impact on performance, enabling a limiting current density above 2 A cm−2 and a peak power density of 1.4 W cm−2. Maximum energy efficiency of 79 % is achieved. In addition, the root cause of limiting-current behavior in this system is elucidated, where it is found that Br− reversibly adsorbs at the Pt (−) electrode for potentials exceeding a critical value, and the extent of Br− coverage is potential-dependent. This phenomenon limits maximum cell current density and must be addressed in system modeling and design. These findings are expected to lower system cost and enable higher efficiency. © 2014, Springer Science+Business Media Dordrecht. Source


Tucker M.C.,Lawrence Berkeley National Laboratory | Cho K.T.,Northern Illinois University | Weber A.Z.,Lawrence Berkeley National Laboratory | Lin G.,TVN Systems, Inc. | Van Nguyen T.,University of Kansas
Journal of Applied Electrochemistry | Year: 2014

The Br2/H2 redox flow cell shows promise as a high-power, low-cost energy storage device. The effect of various aspects of material selection, processing, and assembly of electrodes on the operation, performance, and efficiency of the system is determined. In particular, (+) electrode thickness, cell compression, hydrogen pressure, and (−) electrode architecture are investigated. Increasing hydrogen pressure and depositing the (−) catalyst layer on the membrane instead of on the carbon paper backing layers have a large positive impact on performance, enabling a limiting current density above 2 A cm−2 and a peak power density of 1.4 W cm−2. Maximum energy efficiency of 79 % is achieved. In addition, the root cause of limiting-current behavior in this system is elucidated, where it is found that Br− reversibly adsorbs at the Pt (−) electrode for potentials exceeding a critical value, and the extent of Br− coverage is potential-dependent. This phenomenon limits maximum cell current density and must be addressed in system modeling and design. These findings are expected to lower system cost and enable higher efficiency. © 2014, Springer Science+Business Media Dordrecht. Source


Tucker M.C.,Lawrence Berkeley National Laboratory | Cho K.T.,Lawrence Berkeley National Laboratory | Cho K.T.,Northern Illinois University | Spingler F.B.,Lawrence Berkeley National Laboratory | And 2 more authors.
Journal of Power Sources | Year: 2015

Abstract The Br2/H2 redox flow cell shows promise as a high-power, low-cost energy storage device. In this paper, the effect of various aspects of material selection and processing of proton exchange membranes on the operation of the Br2/H2 redox flow cell is determined. Membrane properties have a significant impact on the performance and efficiency of the system. In particular, there is a tradeoff between conductivity and crossover, where conductivity limits system efficiency at high current density and crossover limits efficiency at low current density. The impact of thickness, pretreatment procedure, swelling state during cell assembly, equivalent weight, membrane reinforcement, and addition of a microporous separator layer on this tradeoff is assessed. NR212 (50 μm) pretreated by soaking in 70 C water is found to be optimal for the studied operating conditions. For this case, an energy efficiency of greater than 75% is achieved for current density up to 400 mA cm-2, with a maximum obtainable energy efficiency of 88%. A cell with this membrane was cycled continuously for 3164 h. Membrane transport properties, including conductivity and bromine and water crossover, were found to decrease moderately upon cycling but remained higher than those for the as-received membrane. © 2015 Elsevier B.V. All rights reserved. Source


Grant
Agency: Department of Energy | Branch: ARPA-E | Program: STTR | Phase: Phase I | Award Amount: 225.00K | Year: 2012

"It is our objective to develop a cost effective, durable and reliable hydrogen-bromine flow battery system for small-scale electrical energy storage applications. H2/Br2 flow battery technology has been around for decades, however, the lack of low-cost and durable electrode and membrane materials in addition to non-optimal cell/stack configurations have prevented this technology from widespread deployment. TVN Systems Inc. teams up with research groups at Vanderbilt University and The University of Kansas to develop innovative electrodes, membranes and optimal cell/stack design to reduce cost and to increase cycle life and overall efficiency of an H2/Br2 flow battery system. In Phase I we will (1) identify and fabricate inexpensive and durable electrocatalysts and nanofiber composite membranes to replace platinum-based electrode materials and Nafion membranes, and (2) develop optimal electrode and cell design. In Phase II, a 250W stack module will be developed employing the new materials and optimal cell design to demonstrate the cost reduction and performance gain as opposed to stacks using state-of-the-art materials. A number of modules can be combined in parallel to support large power demands. An analysis on a 2.5kW-4hour energy storage system consisting of ten proposed modules shows that it meets the ARPA-E’s primary targets: 1.2m3 footprint, at least 80% round trip efficiency, lifetime more than 1250 cycles and under $1000 per unit. It can be charged by solar power systems or electric grids to store off-peak electricity at customer’s location. The success of this project will be truly transformational for large-scale H2/Br2 electrochemical energy storage systems to have a greater impact on economic and energy security of the United States."


Grant
Agency: Department of Energy | Branch: ARPA-E | Program: STTR | Phase: Phase II | Award Amount: 1.50M | Year: 2012

"It is our objective to develop a cost effective, durable and reliable hydrogen-bromine flow battery system for small-scale electrical energy storage applications. H2/Br2 flow battery technology has been around for decades, however, the lack of low-cost and durable electrode and membrane materials in addition to non-optimal cell/stack configurations have prevented this technology from widespread deployment. TVN Systems Inc. teams up with research groups at Vanderbilt University and The University of Kansas to develop innovative electrodes, membranes and optimal cell/stack design to reduce cost and to increase cycle life and overall efficiency of an H2/Br2 flow battery system. In Phase I we will (1) identify and fabricate inexpensive and durable electrocatalysts and nanofiber composite membranes to replace platinum-based electrode materials and Nafion membranes, and (2) develop optimal electrode and cell design. In Phase II, a 250W stack module will be developed employing the new materials and optimal cell design to demonstrate the cost reduction and performance gain as opposed to stacks using state-of-the-art materials. A number of modules can be combined in parallel to support large power demands. An analysis on a 2.5kW-4hour energy storage system consisting of ten proposed modules shows that it meets the ARPA-E’s primary targets: 1.2m3 footprint, at least 80% round trip efficiency, lifetime more than 1250 cycles and under $1000 per unit. It can be charged by solar power systems or electric grids to store off-peak electricity at customer’s location. The success of this project will be truly transformational for large-scale H2/Br2 electrochemical energy storage systems to have a greater impact on economic and energy security of the United States."

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