Researchers at the US Department of Energy’s (DOE) Brookhaven National Laboratory have designed a new, sulfur-based organic cathode material for lithium batteries. The material is more energy-dense, cost-effective, and environmentally friendly than traditional cathode materials in lithium batteries. The research is published in Advanced Energy Materials.
The researchers chose an innovative organodisulfide compound for the cathode material—2,3,4,6,8,9,10,12‐Octathia biscyclopenta[b,c]‐5,11‐anthraquinone‐1,7‐dithione (TPQD). TPQD can deliver an initial capacity of 251.7 mAh g−1 at a rate of C/10, which corresponds to the transfer of 4.7 electrons per formula.
Highly reversible capacities and stable cyclic performances can be achieved at rates from C/10 to 5 C. TPQD can retain a capacity of 120 mAh g−1 after 200 cycles at the 5 C rate—quite impressive for organodisulfide compounds.
X‐ray absorption spectroscopy measurements and density functional theory calculation results suggest that such a high capacity is contributed by both O redox of the quinone group and the cleavage and recombination of the disulfide bond. Moreover, the extended π‐conjugation structure of the material, introduced by benzoquinone and dithiane, is beneficial for improving the high rate capability and cyclic stability.—Shadike et al.
Once the scientists in Brookhaven’s Chemistry Division designed and synthesized the new material, they then brought it to NSLS-II to better understand its charge-discharge mechanism. Using NSLS-II’s ultrabright x-rays at two different experimental stations, the X-ray Powder Diffraction (XPD) beamline and the In situ and Operando Soft X-ray Spectroscopy (IOS) beamline, the scientists were able to determine how specific elements in the cathode material contributed to its performance.
The results from NSLS-II and additional experiments at the Canadian Light Source enabled the scientists to successfully confirm the battery’s charge-discharge capacity provided by the sulfur atoms. The researchers say this study provides a new strategy for improving the performance of sulfur-based cathodes for high performance lithium batteries.
This study was supported by DOE’s Office of Energy Efficiency and Renewable Energy. Operations at NSLS-II are supported by DOE’s Office of Science.
Shadike, Z., Lee, H.‐S., Tian, C., Sun, K., Song, L., Hu, E., Waluyo, I., Hunt, A., Ghose, S., Hu, Y., Zhou, J., Wang, J., Northrup, P., Bak, S.‐M., Yang, X.‐Q. (2019) “Synthesis and Characterization of a Molecularly Designed High‐Performance Organodisulfide as Cathode Material for Lithium Batteries.” Adv. Energy Mater. 2019 doi: 10.1002/aenm.201900705