Ammonium Sulfate-ModifiedPolyaniline-Derived CarbonNanofibers as Sodium-Ion Battery Anodes

Here, (NH4)2SO4-assisted pyrolysis strategy was proposed to modulate the nanopore structure and surface properties of polyaniline-derived carbon nanofibers (PANI-CFs), in which (NH4)2SO4 plays a critical role in promoting the pyrolysis of PANI, with accompanying contributions as heteroatom dopants and pore-forming agents. The amount of (NH4)2SO4 added has a significant impact on the structural properties of PANI-CFs. Benefiting from these structural and chemical regulations, the tailored PANI-CFs-1.5 anode delivers reversible capacities of 410, 393, 340, 305, 217, 128, and 112 mAh·g–1, at 0.05, 0.1, 0.2, 0.3, 0.5, 1.0, and 2.0 A·g–1, respectively. More importantly, it exhibits exceptional cycling stability, retaining 347 mAh·g–1 after 200 cycles at 0.05 A·g–1 and 189 mAh·g–1 after 1500 cycles at 0.3 A·g–1. Furthermore, the sodium-ion storage mechanism of PANI-CFs, which is rooted in the sequential adsorption-intercalation-pore-filling charge-storage pathway, is proposed.