Molecular Engineering of Monodisperse SnO₂ Nanocrystals Anchored on Doped Graphene with High‐Performance Lithium/Sodium‐Storage Properties in Half/Full Cells

Abstract The fabrication of ultrasmall and high‐content SnO₂ nanocrystals anchored on doped graphene can endow SnO₂ with superior electrochemical properties. Herein, an effective strategy, involving molecular engineering of a layer‐by‐layer assembly technique, is proposed to homogeneously anchor SnO₂ nanocrystals on nitrogen/sulfur codoped graphene (NSGS), which serves as an advanced anode material in lithium/sodium‐ion batteries (LIBs/SIBs). Benefiting from novel design and specific structure, the optimized NSGS for LIBs displays high initial capacity (2123.9 mAh g⁻¹ at 0.1 A g⁻¹), long‐term cycling performance (only 0.8% loss after 500 cycles), and good rate capability (477.4 mAh g⁻¹ at 5 A g⁻¹). In addition, the optimized NSGS for SIBs also delivers high initial capacity (791.7 mAh g⁻¹ at 0.1 A g⁻¹) and high reversible capacity (180.2 mAh g⁻¹ after 500 cycles at 0.5 A g⁻¹). Meanwhile, based on the detailed analysis of phase transition and electrochemical reaction kinetics, the reaction mechanisms of NSGS in LIBs and SIBs as well as the distinction in LIBs/SIBs are clearly articulated. Notably, to further explore the practical application, Li/Na⁺ full cells are also assembled by coupling the optimized NSGS anode with LiCoO₂ and Na₃V₂(PO₄)₃/C cathodes, respectively.