Enhancing the Capacity and Stability of a Tungsten Disulfide Anode in a Lithium-Ion Battery Using Excess Sulfur.

Tungsten disulfide (WS) is a transition metal disulfide and a promising anode material due to its layered structure, making it favorable for attaining lithium-ion batteries with rate capability and thermal/mechanical stability. Although WS has a rich redox chemistry and a large density, which can increase the specific capacity and volumetric energy density, it still has an inferior specific capacity and poor long-term stability for practical use due to its insufficient space for the accommodation of lithium ions and large volume change during cycling. Herein, to overcome the chronic limitations of WS-based anodes, we propose a micron-sized tungsten disulfide/reduced graphene oxide composite by employing excess sulfur (S-WS/r-GO).

In Situ Self-Formed Nanosheet MoS/Reduced Graphene Oxide Material Showing Superior Performance as a Lithium-Ion Battery Cathode.

Although lithium-sulfur (Li-S) batteries have 5-10 times higher theoretical capacity (1675 mAh g) than present commercial lithium-ion batteries, Li-S batteries show a rapid and continuous capacity fading due to the polysulfide dissolution in common electrolytes. Here, we propose the use of a sulfur-based cathode material, amorphous MoS and reduced graphene oxide (r-GO) composite, which can be substituted for the pure sulfur-based cathodes. In order to enhance kinetics and stability of the electrodes, we intentionally pulverize the microsized MoS sheet into nanosheets and form an ultrathin nano-SEI on the surface using in situ electrochemical methods.