In SituSelf-Formed Nanosheet MoS3/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 –1 ) 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 3 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 3 sheet into nanosheets and form an ultrathin nano-SEI on the surface using in situ electrochemical methods. Then, the pulverized nanosheets are securely anchored by the oxygen functional group of r-GO. As a result, the electrochemically treated MoS 3 /r-GO electrode shows superior performance that surpasses pure sulfur-based electrodes; it exhibits a capacity of about 900 mAh g –1 at a rate of 5C for 2500 cycles without capacity fading. Moreover, a full-cell battery employing the MoS 3 /r-GO cathode with a silicon–carbon composite anode displays a 3–5 times higher energy density (1725 Wh kg –1 /7100 Wh L –1 ) than present LIBs.