In situ synthesis of hierarchical CoFe2O4 nanoclusters/graphene aerogels and their high performance for lithium-ion batteries

Abstract

In this article, we demonstrate a simple solvothermal method towards in situ growth of hierarchical CoFe₂O₄ nanoclusters on graphene aerogels (GAs). SEM and TEM results confirm that CoFe₂O₄ nanoclusters are well wrapped by the graphene skeleton. As an anode material for lithium-ion batteries, the CoFe₂O₄/GAs composite displays a stable cycling performance with a reversible capacity of over 100 discharge/charge cycles at the current density of 0.1 A g⁻¹, considerably higher than that of CoFe₂O₄ nanoclusters. Moreover, the reversible capacity of the CoFe₂O₄/GAs composite exhibits 966 mA h g⁻¹ after 300 cycles even at a high current density of 0.5 A g⁻¹. Most important of all, a new CoFe₂O₄/GAs//LiCoO₂ full cell was successfully assembled, and this exhibited excellent electrochemical performance. The superior electrochemical performance of the CoFe₂O₄/GAs composite in half and full cells can be attributed to the synergistic interaction between the uniform CoFe₂O₄ nanoclusters and GAs, the high electrical conductivity, and the three-dimensional hierarchically porous structure, which can not only facilitate the diffusion of Li ions and electrolyte into the electrodes, but also prevent volume expansion/contraction upon prolonged discharge/charge cycling.