Sulfur-doped porous carbon nanosheets from ice template-induced assembly of sulfonated naphthalene for lithium-ion battery anodes

Abstract

Porous carbon nanosheets (PCNSs) containing both sheet-like structure and porous architecture are considered promising candidates as anode materials for lithium-ion batteries (LIBs). In this work, sulfur-doped porous carbon nanosheets (SPCNSs) are prepared via an ice template-induced assembly coupled with carbonization strategy employing low-cost sulfonated naphthalene as a precursor. During freezing, sulfonated naphthalene molecules arrange along the directional growth of ice crystals, forming sheet-like morphology which is preserved after sublimation of ice. Subsequent carbonization induces polymerization of these molecules, enabling their assembly into large-area carbon nanosheets. The prepared SPCNSs have well-developed porous structure with substantial specific surface area (831.7 m²/g) and pore volume (0.613 cm³/g), large transverse size nanosheets and ultrahigh S doping (7.33 at%). The SPCNSs applied as anode materials for LIBs present an initial high reversible capacity (2027 mAh/g at 0.1 A/g), excellent rate capability (258 mAh/g at 2.0 A/g), and outstanding cycling stability (438 mAh/g at 1.0 A/g after 600 cycles). This study provides a green and effective route to produce SPCNSs via the assembly of molecules sulfonated naphthalene in an ice template, demonstrating promising industrial application potential as anode materials for LIBs.