Molecular Engineering of Monodisperse SnO_2 Nanocrystals Anchored on Doped Graphene with High-Performance Lithium/Sodium-Storage Properties in Half/Full Cells

摘要

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.