Nitrogen-atom doped graphene oxide was considered to prevent the dissolution of polysulfide and to guarantee the enhanced redox reaction of sulfur for good cycle performance of lithium sulfur cells. In this study, we used urea as a nitrogen source due to its low cost and easy preparation. To find the optimum urea content, we tested three different ratios of urea to graphene oxide. The morphology of the composites was examined by field emission scanning electron microscope. Functional groups and bonding characterization were measured by X-ray photoelectron spectroscopy. Electrochemical properties were characterized by cyclic voltammetry in an organic electrolyte solution. Compared with thermally reduced graphene/sulfur (S) composite, nitrogen-doped graphene/S composites showed higher electroactivity and more stable capacity retention.

• Ki-Yong Kim(School of Chemical and Biochemical Engineering, Pusan National University, Busan 46241, Korea)
• Yongju Jung(Department of Chemical Engineering, Korea University of Technology and Education, Cheonan 31253, Korea)
• Seok Kim(School of Chemical and Biochemical Engineering, Pusan National University, Busan 46241, Korea) Corresponding Author