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.

Three‐Dimensional Porous CoFe2O4/Graphene Composite for Highly Stable Sodium‐Ion Batteries

“…The unique porous characteristic of CoFe 2 O 4 @3D-NG is conducive to offering shorten ionic and mass transport distance, rich active sites and enhanced structural stability upon the electrochemical reaction, promoting efficient Na-storage. [12,26] Surprising, the CV curves of the subsequent cycles are observed to be identical with each other, implying the excellent reversibility of the electrode. In the first cathodic scan curve, a representative reduction peak was observed around 0.25 V, which is associated with the conversion reaction of Fe 3 + and Co 2 + to their metallic states of Fe and Co. [12,14,18,33] In the first anodic scan process, the broad oxidation peak located at about 1.5 V is assigned to the oxidation reaction of the metallic Fe and Co to Fe 3 + and Co 2 + .…”

“…To verify the advantages of the CoFe 2 O 4 @3D-NG composite as anode material for SIBs, the electrochemical performances were investigated by assembling 2032-type coin cells with Na metal as a counter/reference electrode in a voltage range of 0.01 and 3.0 V. Figure 7a presents the cyclic voltammetry (CV) curves of the CoFe 2 O 4 @3D-NG electrode for the initial four cycles at a scan rate of 0.02 mV s À 1 . [12,26,43,44] @3D-NG composite for the initial four cycles at a scan rate of 0.2 mV s À 1 in the potential range of 0.01-3.0 V. b) Charge-discharge curves of the CoFe 2 O 4 @3D-NG composite at a current density of 50 mA g À 1 . [12,14,18,33] To further prove this point, post-XPS analysis for the cycled electrode was also conducted.…”

“…[8][9][10] However, the inherently dramatic volume variation of binary TMOs resulted from the Na + insertion/extraction would lead to electrode pulverization and inferior electrical contact with the current collector, giving rise to rapid capacity decaying and weak cycling stability. [17][18][19][20][21][22][23][24][25][26][27] Herein, a facile two-step hydrothermal method was employed to synthesis novel CoFe 2 O 4 /graphene composite, in which nanoporous CoFe 2 O 4 hollow spheres were well anchored onto 3D nitrogen-doped graphene networks (CoFe 2 O 4 @3D-NG). [12][13][14] In this strategy, the relatively inactive metal component towards Na can act as a buffer matrix to reduce the effect of volume variation of the active one, maintaining the structural stability of the electrode upon the cycling process.…”

Critical Insight into the Relentless Progression Toward Graphene and Graphene‐Containing Materials for Lithium‐Ion Battery Anodes

“…Other full-cells comprising non-pre-lithiated RGO/SnO 2 -Fe 3 O 4 , [ 412 ] RGO/SnS 2 , [ 413 ] pre-lithiated RGO/SnS 2 [ 413 ] and RGO/ CoFe 2 O 4 [ 414 ] composite anodes coupled with LiCoO 2 cathodes were also tested (Table 3 ). However, only the full-cells using the pre-lithiated anodes showed acceptable performance in terms of low 1 st cycle irreversible capacity and rate capability.…”

Zn substitution NiFe2O4 nanoparticles with enhanced conductivity as high-performances electrodes for lithium ion batteries

“…Each plot consists of a semicircle in the high medium frequency range and an inclined line in the low frequency region. The semicircles in high and middle frequency are relative to the SEI resistance (R f ), charge transfer resistance (R ct )[59,60]. The inclined line is assigned to the Warburg impedance data are fitted to the equivalent circuit shown inFig.…”