Double-protected zinc ferrite nanospheres as high rate and stable anode materials for lithium ion batteries

Zinc ferrite (ZFO) is a promising anode material to replace the conventional graphite used in lithium ion batteries . However, the unstable structure and poor electrical conductivity of ZFO hinder its practical applications. In this work, carbon-coated ZFO nanospheres anchored on the reduced graphene oxide (C/ZFO/rGO) was synthesized by the solvothermal method and subsequent carbonization with an ionic liquid . In such a sandwich structure, ZFO nanospheres are double-protected by rGO and ionic liquid-derived carbon to maintain structural integrity and enhance electrical conductivity . It was found that the discharge/charge specific capacity of lithium ion batteries with C/ZFO/rGO is capable to maintain to be 963/952 mAh g −1 after 60 cycles at a current density of 0.3 A g −1 . Its discharge/charge specific capacity can maintain to be 183.3/180.2 mAh g −1 even after 2000 cycles at a current density of 8 A g −1 . The improved cycling performance and enhanced rate capability can be explained by the enhanced electrode kinetics and less degradation of structural integrity resulted from the double-protected sandwich structure.