Schematic diagram of the WS2@graphene nanocomposites. Su et al. Click to enlarge.

XRD, FESEM, and TEM analyses of the prepared material showed that the WS₂ nanocrystals were homogeneously distributed on the graphene nanosheets.

Anodes were prepared by dispersing 70 wt. % as-prepared materials, 20 wt. % acetylene carbon black, and 10 wt. % PVDF binder in N-methyl-2-pyrrolidone (NMP) to form a slurry. The resultant slurry was pasted onto copper foil using a doctor blade and dried in a vacuum oven for 12 h, which was followed by pressing at 200 kg cm^-2. The typical loading of each electrode was approximately 1.2 mg cm^-2.

Electrochemical measurements were carried out using two-electrode coin cells (CR2032) with Na metal as reference and counter electrode and glass microfiber as the separator.

… the WS2@graphene nanocomposite showed its highly reactive nature towards sodium storage. It demonstrated a high reversible specific capacity of about 594 mA h g^-1, excellent cyclability, and a good high rate performance, which could be ascribed to the highly conductive graphene matrix and the unique 3D architecture of the nanocomposite. WS2@graphene nanocomposite is a promising high performance anode material for Na-ion batteries.

—Su et al.

Resources

• Dawei Su, Shi Xue Dou and Guoxiu Wang (2014) “WS2@graphene Nanocomposites as Anode Materials for Na-ion Batteries with Enhanced Electrochemical Performances” Chem. Commun. doi: 10.1039/C4CC00840E