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

Abstract

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.