Confining ultrahigh oxygen vacancy SnO2 nanocrystals into nitrogen-doped carbon for enhanced Li-ion storage kinetics and reversibility

Abstract

Oxygen vacancies (VO) engineering has been deemed to an effective tactic for enhancing Li-ion storage kinetics and reversibility of SnO2-based anode materials. Herein, we demonstrated the confinement of ultrahigh VO SnO2 nanocrystals into N-doped carbon frameworks to boost their high-rate and cycle life. Density functional theory (DFT) calculations reveal that abundant VO in SnO2 facilitates the adsorption to Li-ion with remarkably increased carrier concentration. The 6.0 nm-sized SnO2 particles and the embedded design effectively stabilize the structural integrity during de-/lithiation. Meantime, the as-formed large hetero-interface also expedites the electron transfer. These merits guarantee its high-rate performance and superior cycling stability. Consequently, this sample exhibits a high capacity of 1368.9 mAh g−1 at 0.1 A g−1, and can still maintain 488.5 mAh g−1 at 10 A g−1 and a long life over 400 cycles at 5 A g−1 with 96.6% capacity retention, which is among the best report for Sn-contained anode materials. This work sheds light on ultrahigh Vo and structural design in conversion-type oxides for high-performance lithium-ion batteries (LIBs).