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Temperature-Dependent Electrochemical Characteristics of Antimony Nanocrystal Alloying Electrodes for Na-Ion Batteries

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journal contribution
posted on 22.08.2019, 13:34 by Grant A. Williamson, Victor W. Hu, Thomas B. Yoo, Martin Affandy, Charles Opie, Emilee K. Paradis, Vincent C. Holmberg
Nanostructured antimony is a highly promising alloying electrode material for both Li-ion and Na-ion battery systems, possessing a large gravimetric charge storage capacity (660 mAh g–1) combined with extraordinary rate capability (cycling at a 20C rate results in only a ∼15% decrease in capacity, relative to 1C). However, temperature can strongly affect the performance of these antimony electrode materials, and their temperature-dependent cycling remains largely unexplored. Changes in temperature-dependent cycling characteristics can occur via a variety of mechanisms, potentially resulting in either reversible or irreversible loss of capacity at lower temperatures. Here, we utilize temperature-dependent electrochemical impedance spectroscopy (EIS) to investigate the source of performance changes in these Na-ion battery electrode materials. We find that increased charge transfer resistance is predominantly responsible for the observed 100 mAh g–1 capacity reduction (∼20%) upon changing the cycling temperature from 50 to 5 °C, with the double layer capacitance remaining largely unchanged, negligible resistive and capacitive contributions from charge transfer or ion mobility through the solid–electrolyte interphase (SEI) layer, and slight changes in the Na-ion solid-state diffusion rate in the antimony nanocrystals. As such, the observed decrease in capacity at low temperature is almost entirely caused by increased charge transfer resistance due to less facile Na-ion transport across the SEI-layer–electrode interface.