Fabrication of Microporous Sulfur-Doped Carbon Microtubes for High-Performance Sodium-Ion Batteries

Developing efficient anode materials for sodium-ion batteries (SIBs) is important for the storage of renewable energy. Inspired by the rapid development of biomass-derived hard carbons and heteroatom-doped carbon materials in various areas, a high-temperature sulfurizing method is exploited for the fabrication of sulfur-doped carbon microtubes (S-CMTs). Owing to high sulfur doping (10.2 wt %) and well-developed microporous structure, the as-prepared S-CMTs show a large charge capacity of 532 mAh g–1 at a current rate of 200 mA g–1, outstanding rate capability (234 mAh g–1 at 2 A g–1), and exceptional cycling stability (281 mAh g–1 after 1000 cycles at 1 A g–1), values that are superior to those of biomass-derived carbons reported previously. The excellent electrochemical performance of S-CMTs in full cells paired with N,B-co-doped carbon-coated Na3V2(PO4)3 cathodes further demonstrates the feasibility of SIBs. The simple synthesis strategy can potentially be extended to other carbon-based anode materials for sodium-ion batteries.