ZnFe2O4@C/graphene nanocomposites as excellent anode materials for lithium batteries

Abstract

ZnFe₂O₄ is a promising anode material for lithium ion batteries (LIBs) because of its high theoretical capacity (1000.5 mA h g⁻¹), but its practical application is impeded by fast capacity fading and poor rate capability. To overcome these limitations, herein, core–shell structured ZnFe₂O₄@C nanoparticles were homogeneously anchored onto the surface of graphene (G) nanosheets through a mussel-inspired process and subsequent calcinations. The resulting ZnFe₂O₄@C/G nanocomposite delivered a reversible capacity of 705 mA h g⁻¹ at 0.25 C after 180 cycles (with capacity retention of 99.4%), and high rate capability of 403.5 mA h g⁻¹ at 5 C, thus exhibiting one of the best lithium storage properties among the reported ZnFe₂O₄ anodes. The excellent electrochemical performance is mainly related to the conducting, buffering and protective effects of carbon shells and graphene nanosheets on ZnFe₂O₄ nanoparticles. Considering its simplicity and effectiveness, this strategy might be extended to other anode materials with intrinsically low electronic conductivity, large volume-variation and severe agglomeration in the process of lithiation–delithiation.