▎ 摘　　要

Among promising substitutions for commercial graphite anodes for lithium ion batteries, SnO2 has a fourfold theoretical capacity of graphite (if the O element is completely reversible), while the oxygen reutilization is seriously hampered by poor conductivity of both the electron and Li+ ions. This work proposes a novel ternary architecture of SnO2@C quantum dots (QDs, with average diameter of 3.37 nm) grafted on graphene oxides, denoted as SnO2@C/G, via a facile and scalable one-pot hydrothermal method. The SnO2@C/G show extraordinary long-term cycling performance (1080 mAh g(-1) at 200 mA g(-1) after 300 cycles) and rate capability (similar to 840 mAh g(-1) at 2A g(-1)). If excluding the contribution of carbon, the specific capacity of SnO2 is 1447 mAh g(-1) at 200 mA g(-1), 96.9% of its theoretical capacity. The extraordinary performance is ascribed to ultrahigh reversibility of SnO2 QDs, good structural stability, and much better ionic/electronic diffusions confirmed by XPS, TEM, EIS, respectively.