Sodium is a promising alternative anode material with advantages of high abundance, low cost, and suitable redox potential (~2.71 V). Sulfur, as one of the most abundant elements on earth, is considered as an attractive cathode material owing to its high theoretical capacity of 1675 mA h g^-1 and high energy density of 2600 W h kg^-1. It is well known that sodium-sulfur (Na-S) battery has been widely used for stationary energy storage, operating at a high temperature condition. In recent years, much effort has been devoted to develop Na-S batteries at ambient temperature to overcome the safety drawback [1-3]. However, more challenges exist in room temperature (RT) NaS batteries such as dissolution of intermediate polysulfides into the electrolyte, low utilization of active material, and poor cycle life. In this work, nitrogen-doped graphene nanosheets (NGNS) interlinked with sulfur has been used as an electrode material for RT Na-S batteries. This nanocomposite was synthesized via an chemical reaction-deposition and thermal treatment strategy. Two series samples with both high and low sulfur content levels in the nanocomposites have been developed. Characterizations testing such as SEM, XPS and XRD have been conducted and the results from electrochemical testing show that the first cycle discharge/charge capacities of the low loading sulfur-NGNS composite at 0.05C have been reached 212 mA h g^-1 and 181 mA h g^-1. The low loading sulfur-NGNS composite also presented notable cycling life with 300 cycles at 0.1C and the capacity remained at 55 mA h g^-1, indicating good cyclic retention. Detailed discussion on the characterization and electrochemical performance of the synthesized NGNS/S nanocomposite will be presented in the meeting.

References

1.  T.H. Hwang, D.S. Jung, J.S. Kim, B.G. Kim, J.W. Choi, Nano Lett., 13, 4532 (2013).

2.  S. Xin, Y.X. Yin, Y.G. Guo, L.J. Wan, Adv. Mater., 26, 1261 (2014).

3.  S. Zheng, P. Han, Z. Han, P. Li, H. Zhang, J. Yang, Adv. Energy Mater., 4 (2014).