Lithium-ion batteries provide, on average, a near 150 Wh/kg energy density and capacity near 170 mAh/g ^[1]. Other lithium energy storage chemistries such as lithium-air and lithium-sulfur have been proposed as potential higher energy (11680^[2], 2500^[3]  Wh/kg) capacity alternatives; however, various issues plague these battery types, ultimately affecting the energy and performance. Lithium-air batteries suffer from poor cyclability (~60-70% efficiency) and materials issues stemming from moisture and poor separation of environmental contaminants^[2]. Lithium-sulfur suffer from capacity fading (>10% over 100 cycles) and loss of active material due to polysulfide dissolution^[5]. Recently, studies using a lithium-bromide chemistry have shown promising results as a rechargeable alternative to lithium-ion batteries, including energy densities of 1220 Wh/kg^[6] and efficiencies between 90%^[7] and 99.5%^[8].

In order to investigate the viability of rechargeable lithium-bromide batteries, studies were conducted with graphite and brominated electrodes in an electrolyte utilizing the highly soluble Br₃^-/Br^- redox couple. Characterization of the electrodes and brominated particles were completed using X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDS), and Transmission Electron Microscopy (TEM). From electrochemical experiments, Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS), the electrodes display behaviors consistent with pseudo-batteries, containing both capacitive and faradaic responses; additionally, higher activity (up to 2x the current density of untreated graphite) is seen with the brominated electrodes. The results of these analyses will be presented, and the implications for rechargeable lithium-bromide batteries will be discussed.

References

1. B. Scrosati and J. Garche, Journal of Power Sources, 195, 2419-2430 (2010).

2. G. Girishkumar, et. al., Journal of Physical Chemistry Letters, 1, 2193-2203 (2010).

3. L. Chen and L.L. Shaw, Journal of Power Sources, 267, 770-783 (2014).

4. P. Leung, et. al., RSC Advances, 2, 10125-10156 (2012).

5. A. Manthiram, Y. Fu, and Y-S. Su, Accounts of Chemical Research, 46 (5), 1125-1134 (2013).

6. Z. Chang, et. al., Journal of Materials Chemistry A, 2, 19444-19450 (2014).

7. Y. L. Wang, et. al., Journal of Materials Chemistry A, 3, 1879-1883 (2015).

8. K. Takemoto and H. Yamada, Journal of Power Sources, 281, 334-340 (2015).

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