Tri‐Heteroatom‐Doped Graphene: From Li‐Ion Battery Anode to NaCl‐Template‐Derived Porous BN Nanosheet‐Supported Cathode for High‐Performance Li–S Battery

ABSTRACT Heteroatom doping has been extensively employed in carbon materials to tailor their performance for energy storage applications. However, simultaneously preparing multi‐heteroatom‐doped electrode materials and clarifying the synergistic effect between heteroatoms on electrochemical energy storage, remains a significant challenge. Herein, nitrogen, boron, and sulfur tri‐doped porous graphene (NBSG) is synthesized via the thermal pyrolysis of graphene oxide pre‐supported polyaniline in the presence of ammonium borate and L‐cysteine. Subsequently, the porous boron nitride@S converted by NBSG is fabricated into a sandwich‐type cathode (pBN@S@NBSG) for the first time, where pBN is synthesized through a NaCl template. Comprehensive structural characterizations coupled with kinetics analysis reveal that the tri‐doped heteroatoms, expanded G interlayers, and pBN synergistically induce sufficient structural defects, which in turn generate abundant adsorption and nucleation sites, thereby providing a promising platform for the fabrication of multifunctional electrodes. As anodes, the NBSG exhibits a high reversible capacity of 531 mAh g ⁻¹ at 2 A g ⁻¹ after 400 cycles and excellent rate capability. Furthermore, the pBN@S@NBSG cathode shows a high specific capacity of 769 mAh g ⁻¹ at 1.7 A g ⁻¹ after 800 cycles, which is mainly attributed to the tolerance of the volume expansion of sulfur and strong adsorption ability to polysulfides.