Microporous Carbon Polyhedrons Encapsulated Polyacrylonitrile Nanofibers as Sulfur Immobilizer for Lithium-Sulfur Battery

Zhang, YZ (Zhang, Ye-Zheng)^[ 1 ] ; Wu, ZZ (Wu, Zhen-Zhen)^[ 1 ] ; Pan, GL (Pan, Gui-Ling)^[ 2 ] ; Liu, S (Liu, Sheng)^[ 1 ] ; Gao, XP (Gao, Xue-Ping)^[ 1 ]

ACS APPLIED MATERIALS & INTERFACES, 2017, 9(14): 12436-12444

DOI: 10.1021/acsami.7b00389

 WOS:000399354100032

Abstract:

Microporous carbon polyhedrons (MCPs) are encapsulated into polyacrylonitrile (PAN) nanofibers by electrospinning the mixture of MCPs and PAN. Subsequently, the as prepared MCPs-PAN nanofibers are employed as sulfur immobilizer for lithium-sulfur battery. Here, the S/MCPs-PAN multi composites integrate the advantage of sulfur/microporous carbon and sulfurized PAN. Specifically, with large pore volume, MCPs inside PAN nanofibers provide a sufficient sulfur loading. While PAN-based nanofibers offer a conductive path and matrix. Therefore, the electrochemical performance is significantly improved for the S/MCPs-PAN multicomposite with a suitable sulfur content in carbonate-based electrolyte. At the current density of 160 mA g(sulfur)(-1), the S/MPCPs-PAN composite delivers a large discharge capacity of 789.7 mAh g(composite)(-1), high Coulombic efficiency of about 100% except in the first cycle, and good capacity retention after 200 cycles. In particular, even at 4 C rate, the S/MCPs-PAN composite can still release the discharge capacity of 370 mAh g(composite)(-1). On the contrary, the formation of the thick SEI layer on the surface of nanofibers with a high sulfur content are observed, which is responsible for the quick capacity deterioration of the sulfur-based composite in carbonate based electrolyte. This design of the S/MCPs-PAN multicomposite is helpful for the fabrication of stable Li-S battery.