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New Cathode Material Could Iron Out Cost Challenge for Energy Storage Batteries

April 2015

Developing advanced and reliable electrical energy-storage systems are critical to stimulate the growth and integration of renewable electricity generation from wind and solar power resources onto the power grid. Sodium-metal halide batteries are receiving growing attention and researchers at PNNL are studying a more economical, novel variant: the sodium–iron chloride (Na-FeCl2) battery. Experimental results show the capacity and energy density of intermediate temperature (<200°C) sodium-iron chloride batteries are comparable to their more popular nickel-based cousins; however, replacing nickel with iron could result up to a 61% reduction in cell materials costs.

Sodium-metal halide batteries are the leading electrochemical devices for stationary energy storage applications because of their long cycle life, safety, and reliability. However, sodium-metal battery's most promising anode/cathode chemistry, sodium–nickel chloride (Na–NiCl2), presents great challenges for practical application due to the high material cost of the nickel cathode. Cheaper iron cathodes could allow greater adoption of sodium-metal halide batteries, but first PNNL researchers needed to find an economical means to remove the strong passivation oxide layer of iron that shields it from chemical reactions. To overcome the layer, PNNL identified for the first time sodium polysulfide-based additives that allow the assembly of iron cathodes, potentially paving the way for increased use of sodium-metal halide batteries.

In addition to improving renewables integration and grid reliability, advances in energy storage can support increased use of electrically powered transportation methods to further reduce greenhouse gas emissions.

This work was supported by the U.S. DOE Office of Electricity Delivery and Energy Reliability. X-ray photoelectron spectroscopy (XPS) characterizations were performed in the Environmental Molecular Sciences Laboratory, a national scientific user facility located at PNNL and sponsored by DOE's Office of Biological and Environmental Research.

Citation: Li, G., Lu, X., Kim, J. Y., Viswanathan, V. V., Meinhardt, K. D., Engelhard, M. H. and Sprenkle, V. L. (2015), An Advanced Na–FeCl2 ZEBRA Battery for Stationary Energy Storage Application. Adv. Energy Mater., 1500357. doi:10.1002/aenm.201500357

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