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Efficient composite synthesis boosts battery energy delivery

What is the scientific achievement?

A team of users from the Stony Brook University m2M EFRC developed an efficient, ‘one-pot’ synthesis strategy for composite silver-iron battery materials, capable of delivering 2.4 times the energy density of the same composite formed by conventional mixing.   Intimate contact between the two material components is the reason for the boost in energy density. 

Why does this achievement matter?

New material solutions are required to meet the growing demand for energy storage. Composites can have desirable properties, but often lack efficient preparation methods.  This scalable approach provides a potential solution using an environmentally abundant  material (iron).

What are the details?

Silver-iron composites

Click on the image to download a high-resolution version. (Top) Silver-iron composites made by one-pot synthesis deliver 2.4 times the energy density of the same material made by conventional mixing. (Bottom Left) TEM image of the silver-iron composite battery material made by the new one-pot synthesis method. (Bottom Right) High resolution image showing intimate mixing of silver (red) and iron (green) in the composite. Each image represents an area of ~(200 nm)2.

A series of silver ferrite/maghemite composite materials (AgxFeOy) have been prepared via a non-stoichiometric, one-pot co-precipitation strategy.  The impact of a one-pot composite preparation on electrochemistry was determined by comparison to a mechanical mixture of nanocrystalline AgFeO2 and Fe2O3 powders, which were combined to afford an overall composition of Ag0.2FeO1.6. Notably, following 30 discharge-charge cycles, the one-pot Ag0.2FeO1.6 composite delivers an energy density (156 mWh/g) profoundly higher than the mechanical mixture Ag0.2FeO1.6 (67 mWh/g).  AgxFeOy composites with the lowest silver content and smallest crystallite size (Ag0.2FeO1.6) deliver twice the discharge energy density (169 mWh/g) of stoichiometric Ag0.2FeO2 with no maghemite component, and exhibited good capacity retention over 50 cycles.  The notable electrochemistry of one-pot AgxFeOy composites may involve reduced AgFeO2 and Fe2O3 aggregate sizes and a concomitant increase in AgFeO2/Fe2O3 crystallite contact not achievable through mechanical mixing.

CFN Capabilities:

The CFN Electron Microscopy and Proximal Probes facilities were used to perform TEM and X-ray photoelectron spectroscopy measurements.

Publication Reference

J. L. Durham, C. J. Pelliccione, W. Zhang, A. S. Poyraz, Z. Lin, X. Tong, F. Wang, E. S. Takeuchi, A. C. Marschilok, K. J.Takeuchi, Silver ferrite/maghemite composites and mixtures: Impact of one-pot composite preparation on battery-relevant electrochemistry, Applied Materials Today, DOI:/10.1016/j.apmt.2016.12.003 (2017).

DOI: 10.1016/j.apmt.2016.12.003

Website:

dx.doi.org/10.1016/j.apmt.2016.12.003

Acknowledgement of Support

This work was supported as part of the Center for Mesoscale Transport Properties, an Energy Frontier Research Center supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, under award #DE-SC0012673. This research utilized XPS and TEM resources at the Center for Functional Nanomaterials, which is a U.S. DOE Office of Science Facility, at Brookhaven National Laboratory under Contract No. DE-SC0012704.  XAS data were collected at sector 12-BM at the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

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