Sandwich-like N-doped carbon coated SnNb2O6 nanosheets for high-rate and long-life lithium storage

A novel sandwich-like N-doped carbon coated SnNb2O6 nanosheets (SNO@NC) has been successfully fabricated through a facile calcination of SNO/polyaniline hybrid composites, which were obtained by the polymerization of aniline on SNO nanosheets. A controllable growth of NC nanolayer on the lamellar SNO surfaces endows the as-prepared SNO@NC with hierarchical sandwich-like structure, excellent conductivity and appropriate oxygen vacancies, which greatly restrains the volume expansion of SNO and improve Li ion diffusion abilities during intercalation/deintercalation reaction. As a result, the SNO@NC anode delivers a high reversible capacity of 609.2 mAh g-1 at 100 mA g-1 and 422.4 mAh g-1 at 1000 mA g-1, greatly higher than that of pure SNO (429.2 mAh g-1 at 100 mA g-1 and 166.9 mAh g-1 at 1000 mA g-1). Meanwhile, extremely long cycling stability with a low capacity decay rate (0.017% per cycle over 3000 cycles) has been achieved. This work proposes a novel strategy for engineering hierarchical pore sandwich-like SNO-based anode materials for Li ion batteries.