Facile synthesis of Co3O4/Co@N-doped carbon nanotubes as anode with improved cycling stability for Li-ion batteries

Herein we report Co3O4/Co@N-doped carbon nanotubes (T-Co3O4/Co@NC) as an efficient and highly stable anode material for lithium-ion batteries. T-Co3O4/Co@NC is facilely prepared via the thermal decomposition of Co3[Co(CN)6]2 in N2 and the oxidation in O2. T-Co3O4/Co@NC exhibits a high degree of graphitization and a large specific surface area, thus promoting the conductivity and providing more active sites. More importantly, the proper existence of metallic Co makes the reaction more reversible and thus leading to the improved cycling stability. Specifically, T-Co3O4/Co@NC delivers a high specific capacity of 689.2 mAh g−1 at 500 mA g−1 after 400 cycles with the capacity retention rate of 99.5%. In contrast, Co3O4/Co@N-doped carbon nanoball (B-Co3O4/Co@NC) exhibits a discharge specific capacity of only 247.0 mAh g−1 after 400 cycles, and the capacity retention rate is as low as 30.1%. Furthermore, T-Co3O4/Co@NC also exhibits excellent cycling performance in a full cell, with the coulombic efficiency over 95%, capacity retention rate over 87% after 100 cycles. The improved stability is mainly attributed to the existence of metallic Co which helps to optimize the solid electrolyte interphase film and form carbon nanotubes.