High Sulfur Loading of Cathodes for Li-S Batteries

Lithium sulfur batteries have attracted the most attention owing to their high energy density (2600Wh/kg), while the specific capacity and capacity retention of sulfur electrodes play a crucial role on increasing the energy density of lithium sulfur batteries. Many researches focus on the materials with very high specific capacity per gram of sulfur but very low sulfur content and cells with very low sulfur loading of cathodes [1-3]. In this work, the cells with much higher sulfur loading of electrodes (4.34mg S/cm², named as S-L and 7.24mg S/cm², named as S-H) show better electrochemical performance.

Fig. 1(a) shows the first discharge/charge potential curves of lithium sulfur batteries with S-L and S-H as cathodes. Two plateaus (about 2.35V and 2.10V) in the discharge curve and one plateaus (about 2.20-2.40V) in the charge curve are observed, which agree well with the previous work [4]. Comparison of cycling performance between S-L and S-H cathode was shown in Fig. 1(b). S-L cathode shows an initial specific capacity of 845mAh/g at 50mA/g between 1.50-2.80V, which exhibits a discharge capacity of 763mAh/g after 45 cycles with a capacity retention of 90.3%. Moreover, the cell with S-H cathode delivers 836mAh/g and 754mAh/g at the first cycle and the 25^th cycle, respectively. The excellent electrochemical performance of high sulfur loading of electrodes makes the development of high energy Li-S batteries possible.

Fig. 1 (a) The first discharge/charge potential curves of lithium sulfur batteries with S-L and S-H as cathode between 1.50-2.80V; (b) Comparison of cycling performance between S-L and S-H cathode.

Reference:

[1] F. F. Zhang, X. B. Zhang, Y. H. Dong, L. M. Wang, J. Mater. Chem., 2012, 22, 11452.

[2]   S. Evers, L. F. Nazar, Chem. Commun., 2012, 48, 1233.

[3] G. Zheng, Y. Yang, J.J. Cha, S. S. Hong, Yi Cui, Nano Lett., 2011, 11, 4462.

[4] L. Xiao, Y. Cao, J. Xiao, B. Schwenzer, M. H. Engelhard, L. V. Saraf, Z. Nie, G. J. Exarhos, J. Liu, Adv. Mater., 2012, 24, 1176.