15 research outputs found
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Quantification of the Voltage Losses in the Minimal Architecture Zinc-Bromine Battery Using GITT and EIS
The sources of voltage loss in the minimal architecture zinc bromine battery are characterized using the galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS) on a cell with a three electrode setup. Monitoring of the electrode voltages during charge/discharge indicate the full cell capacity is limited by the Zn/Zn2+ negative electrode. From GITT, the losses in voltage due to mass transport are shown to be relatively small in comparison to the IR resistance in the cell. In addition, it is shown that decreases in the open circuit voltage with respect to theory are likely caused by the complexation of Br2 into BrX−. Using EIS, the charge transfer resistances at each electrode and ohmic resistances of each component are determined. Overall, the main factors restricting the voltage of the cell are the ohmic resistances in the carbon cloth current collectors and in the electrolyte. Additionally, significant charge transfer resistances are observed at the negative electrode near the start of charge and end of discharge, when the amount of zinc plated on the carbon cloth electrode is minimal
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Optimization and Design of the Minimal Architecture Zinc-Bromine Battery Using Insight from a Levelized Cost of Storage Model
This work demonstrates how a levelized cost of storage (LCOS) model can be used to optimize the performance of the minimal architecture zinc bromine battery (MA-ZBB). Cycling data is collected at charge times ranging from 4 to 48 hours and capacities ranging from 320 to 4000 mAh using scaled-up versions of the MA-ZBB. An LCOS model for the entire MA-ZBB system is proposed and used to demonstrate how the energy efficiency/discharge energy trade-off within the system can be exploited to minimize LCOS. The present, unoptimized cell is shown to approach an LCOS of 0.02 kWh−1. At all purchase prices, greater than 60% of the LCOS comes from the capital cost, where the main contributors are the carbon foam electrode and zinc bromine electrolyte in the cell (both accounting for 20% of the total capital cost). In addition, two case studies are conducted which show how the LCOS model can be used to determine the optimal electrode spacing (0.4 cm) and electrolyte concentration (1.0 M) in the cell. Finally, a comparison with existing technologies is conducted, indicating the system-level cost of the MA-ZBB is competitive with lithium-ion, lead-acid, vanadium redox flow, and zinc bromine redox flow batteries
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Galvanostatic interruption of lithium insertion into magnetite: Evidence of surface layer formation
Magnetite is a known lithium intercalation material, and the loss of active, nanocrystalline magnetite can be inferred from the open-circuit potential relaxation. Specifically, for current interruption after relatively small amounts of lithium insertion, the potential first increases and then decreases, and the decrease is hypothesized to be due to a formation of a surface layer, which increases the solid-state lithium concentration in the remaining active material. Comparisons of simulation to experiment suggest that the reactions with the electrolyte result in the formation of a thin layer of electrochemically inactive material, which is best described by a nucleation and growth mechanism. Simulations are consistent with experimental results observed for 6, 8 and 32-nm crystals. Furthermore, simulations capture the experimental differences in lithiation behavior between the first and second cycles
Recommended from our members
Galvanostatic interruption of lithium insertion into magnetite: Evidence of surface layer formation
Magnetite is a known lithium intercalation material, and the loss of active, nanocrystalline magnetite can be inferred from the open-circuit potential relaxation. Specifically, for current interruption after relatively small amounts of lithium insertion, the potential first increases and then decreases, and the decrease is hypothesized to be due to a formation of a surface layer, which increases the solid-state lithium concentration in the remaining active material. Comparisons of simulation to experiment suggest that the reactions with the electrolyte result in the formation of a thin layer of electrochemically inactive material, which is best described by a nucleation and growth mechanism. Simulations are consistent with experimental results observed for 6, 8 and 32-nm crystals. Furthermore, simulations capture the experimental differences in lithiation behavior between the first and second cycles
Membrane-less hydrogen bromine flow battery
In order for the widely discussed benefits of flow batteries for
electrochemical energy storage to be applied at large scale, the cost of the
electrochemical stack must come down substantially. One promising avenue for
reducing stack cost is to increase the system power density while maintaining
efficiency, enabling smaller stacks. Here we report on a membrane-less,
hydrogen bromine laminar flow battery as a potential high power density
solution. The membrane-less design enables power densities of 0.795 W cm
at room temperature and atmospheric pressure, with a round-trip voltage
efficiency of 92\% at 25\% of peak power. Theoretical solutions are also
presented to guide the design of future laminar flow batteries. The high power
density achieved by the hydrogen bromine laminar flow battery, along with the
potential for rechargeable operation, will translate into smaller, inexpensive
systems that could revolutionize the fields of large-scale energy storage and
portable power systems