Free-Standing Porous Carbon Nanofiber/Carbon Nanotube Film as Sulfur Immobilizer with High Areal Capacity for Lithium–Sulfur Battery

Low sulfur utilization and poor cycle life of the sulfur cathode with high sulfur loadings remain a great challenge for lithium–sulfur (Li–S) battery. Herein, the free-standing carbon film consisting of porous carbon nanofibers (PCNFs) and carbon nanotubes (CNTs) is successfully fabricated by the electrospinning technology. The PCNF/CNT film with three-dimensional and interconnected structure is promising for the uniformity of the high-loading sulfur, good penetration of the electrolyte, and reliable accommodation of volumetric expansion of the sulfur cathode. In addition, the abundant N/O-doped elements in PCNF/CNT film are helpful to chemically trap soluble polysulfides in the charge–discharge processes. Consequently, the obtained monolayer S/PCNF/CNT film as the cathode shows high specific capacity, excellent cycle stability, and rate stability with the sulfur loading of 3.9 mg cm^–2. Moreover, the high areal capacity of 13.5 mA h cm^–2 is obtained for the cathode by stacking three S/PCNF/CNT layers with the high sulfur loading of 12 mg cm^–2. The stacking-layered cathode with high sulfur loading provides excellent cycle stability, which is beneficial to fabricate high-energy-density Li–S battery in future.