Polyvinyl Alcohol-derived carbon nanofibers/carbon nanotubes/sulfur electrode with honeycomb-like hierarchical porous structure for the stable-capacity lithium/sulfur batteries

The honeycomb-like hierarchical porous carbon nanofibers (PCNFs)-carbon nanotubes (CNTs)-sulfur(S) composite electrode is successfully desgined and prepared through ball-milling and heating method, in which the PCNFs are carbonized from fibers in the membrane composed of Polyvinyl Alcohol and Polytetrafluoroethylene by electro-blown spinning technology. The prepared PCNFs-CNTs-S composite are regarded as cathode for lithium-sulfur battery . The tailored porous structure and CNTs in the composite facilitate construction of a high electrical conductive pathway and store more S/polysulfides, and the dissoluble loss of intermediate S species in electrolyte can also be restrained because of acidized PVA-based porous carbon nanofibers. Meanwhile, the porous strcucture and CNTs can effectively alleviate volume changes in battery cycling process. Moreover, the presence of LiNO 3 in electrolyte helps the electrochemical oxidation of Li 2 S and LiNO 3 -derived surface film effectively suppresses the migration of soluble polysulfide to the Li anode surface . Therefore, the obtained PCNFs-CNTs-S cathode exhibits excellent performance in Li-S battery with a high initial discharge capacity as high as 1302.9 mAh g −1 , and super stable capacity retention with 809.1 mAh g −1 after 300 cycles at the current density of 837.5 mA g −1 (0.5 C). And the rate capability of PCNFs-CNTs-S electrode is much better than those of CNTs-S and PCNFs-S electrodes.