Fabrication and Characterization of Highly Ordered Graphite Nanofiber Network Structure for Lithium-Sulfur Batteries

Abstract

Graphitic carbon fiber felt (GCFF) with a highly ordered crystalline graphitic carbon structure was fabricated by a combination of electrospinning and graphitization (2800 °C heat treatment) of carbon precursor polymer (PAN; Polyacrylonitrile) and was used as an interlayer between the cathode and separator in Li-S batteries. This GCFF interlayer trapped the polysulfides on the cathode side and increased the utilization of sulfur by suppressing the shuttle phenomenon. Also, the GCFF was shown to be able to act as an upper current collector to reduce the charge-transfer resistance owing to the high crystallinity of the graphitic carbon fibers. The sulfur cathode with the GCFF interlayer showed a high specific initial discharge capacity of 1280 mAh g−1 and excellent cycling stability (1004 mAh g−1 after 100 cycles) at 0.2 C. Also, an image of the glass fiber (GF) separator on the anode side confirmed the presence of an SEI(solid-electrolyte interphase) after 200 cycles, which apparently resulted from stable Li deposition on the Li metal because of the low or medium concentration of sulfur in the electrolyte solution. Our observations should contribute to elucidating the key features of complex three-dimensional carbon fabrics with crystalline graphitic structures that allow them, when inserted as interlayers, to markedly improve the performance of rechargeable batteries. Reference: Journal of Power Sources, Volume 360, 31 August 2017, Pages 559-568