Molecular Structure Regulation of Fccs Enabling N/S Co-Doped Hollow Amorphous Carbon with Enlarged Interlayer Spacing and Rich Defects for Superior Potassium Storage

Abstract

Fluid catalytic cracking slurry (FCCs) features high contents of carbon and aromatic hydrocarbons, serving as a promising precursor for preparing high-performance carbon-based anodes for potassium-ion batteries (PIBs). However, the severe interlayer stacking of planar aromatic hydrocarbons in liquid-phase carbonization results in limited interlayer spacing and inferior K-ion storage behaviors. Herein, by rationally tailoring the molecular structure of FCCs, N/S co-doped hollow amorphous carbon with enlarged interlayer spacing (LNSHAC) was fabricated through a template-assisted strategy. Owing to the enlarged interlayer spacing (0.405 nm), plentiful carbon defects, as well as N/S co-doped hollow structure, the LNSHAC delivers a high reversible capacity (466.2 mAh g-1 at 0.1 A g-1), excellent rate capability (336.3 mAh g-1 at 2 A g-1), and superior cyclic performance (256.9 mAh g-1 after 5000 cycles at 5 A g-1 with an admirable retention of 76.9%), standing out among the reported carbon-based anodes. By employing KFeHCF as the cathode, the LNSHAC-based K-ion full cell shows a high reversible capacity of 176.6 mAh g-1 at 0.1 A g-1 and excellent cyclic stability over 200 cycles. First-principles calculations manifest that the superhigh capacity and rate capability of LNSHAC are ascribed to the synergistic effect of enlarged interlayer spacing and multifarious defects. This work will inspire the development of high-performance but cost-effective carbon-based materials for potassium electrochemical energy storage.

Keywords: Fluid catalytic cracking slurry, Molecular structure regulation, Enlarged interlayer spacing, Carbon defects, potassium-ion batteries