Lithium-sulfur batteries have a five to ten times higher theoretical capacity than commercially used lithium-ion batteries. However, their widespread use has been hampered by continuous capacity fading and dissolution of the electrolyte.

KwangSup Eom, Gwangju Institute of Science and Technology (GIST), Republic of Korea, Han-Ik Joh, Konkuk University, Seoul Republic of Korea, and colleagues have developed a composite cathode material for Li-S batteries which consists of MoS₃ and reduced graphene oxide (rGO) nanosheets. The rGO was synthesized using a modified Hummers method from graphite powder. The MoS₃ was prepared using wet-chemical methods from ammonium tetrathiomolybdate, (NH₄)₂MoS₄. The resulting MoS₃-rGO composite was then freeze-dried and pulverized. The researchers created a nanosized solid electrolyte interphase (SEI) on the surface of the nanosheets using electrochemical methods. This nano-SEI protects the electrode material and improves its stability.

The composite has a high performance, better than pure sulfur-based electrodes. The cathode has a capacity of about 900 mAh g^–1 over 2500 cycles without suffering any capacity fading. The researchers also used the cathode in a full-cell setup alongside a silicon-carbon composite anode and found an energy density of 1725 Wh kg^–1, which is three to five times greater than that of common lithium-ion batteries.

• In Situ Self-Formed Nanosheet MoS₃/Reduced Graphene Oxide Material Showing Superior Performance as a Lithium-Ion Battery Cathode,
  Uijin Chang, Jung Tae Lee, Jin-Mun Yun, Byeongyoung Lee, Seung Woo Lee, Han-Ik Joh, KwangSup Eom, Thomas F. Fuller,
  ACS Nano 2018.
  https://doi.org/10.1021/acsnano.8b07191