Iron vacancies engineering of Fe x C@NC hybrids toward enhanced lithium-ion storage properties.

Defect engineering have profound influence on the energy storage properties of electrode hybrids by adjusting their intrinsic electronic characteristics. For iron carbide based materials, however, the effect of defect (especially cation vacancies) toward their electrochemical performance are still unclear. Herein, the feasible and scalable synthesis of Fe x C@NC with 3D honeycomb-like carbon architecture and abundant Fe vacancies via template etching is reported. Such structure enable outstanding lithium-ion storage properties owing to hierarchical pores, improved intrinsic electrochemical activity, as well as the introduction of more active sites. As a result, the Fe x C@NC-2 presents a high reversible specific capacity of 1079 mAh g -1 after 1000 cycles. Moreover, an excellent cycling stability can be achieved via maintaining a high-capacity retention (689 mAh g -1 , 98.4%) over 1000 cycles at 5 A g -1 . This study provides a feasible strategy for developing high-performance hybrids with hierarchical pore and rich defects structures.