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 SnO 2 nanocrystals anchored on doped graphene can endow SnO 2 with superior electrochemical properties. Herein, an effective strategy, involving molecular engineering of a layer‐by‐layer assembly technique, is proposed to homogeneously anchor SnO 2 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 LiCoO 2 and Na 3 V 2 (PO 4 ) 3 /C cathodes, respectively.