Study on the Electrochemical Reaction Mechanism of NiFe₂O₄ as a High-Performance Anode for Li-Ion Batteries

Abstract

Nickel ferrite (NiFeO) has been previously shown to have a promising electrochemical performance for lithium-ion batteries (LIBs) as an anode material. However, associated electrochemical processes, along with structural changes, during conversion reactions are hardly studied. Nanocrystalline NiFeO was synthesized with the aid of a simple citric acid assisted sol-gel method and tested as a negative electrode for LIBs. After 100 cycles at a constant current density of 0.5 A g (about a 0.5 C-rate), the synthesized NiFeO electrode provided a stable reversible capacity of 786 mAh g with a capacity retention greater than 85%. The NiFeO electrode achieved a specific capacity of 365 mAh g when cycled at a current density of 10 A g (about a 10 C-rate). At such a high current density, this is an outstanding capacity for NiFeO nanoparticles as an anode. Ex-situ X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) were employed at different potential states during the cell operation to elucidate the conversion process of a NiFeO anode and the capacity contribution from either Ni or Fe. Investigation reveals that the lithium extraction reaction does not fully agree with the previously reported one and is found to be a hindered oxidation of metallic nickel to nickel oxide in the applied potential window. Our findings suggest that iron is participating in an electrochemical reaction with full reversibility and forms iron oxide in the fully charged state, while nickel is found to be the cause of partial irreversible capacity where it exists in both metallic nickel and nickel oxide phases.

X‐ray Nano‐computed Tomography of Electrochemical Conversion in Lithium‐ion Battery

“…Advanced ex and in situ measurements have promoted fundamental understanding of the structural and morphological modifications along with the effects of metal oxide composition on the conversion reaction features . Among the various investigative approaches, three‐dimensional imaging at the micro‐ and nanoscale may actually shed light on the particle evolution throughout the lithium‐exchange process and reveal crucial morphological parameters for electrode modelling, such as the phase volume fraction and the particle size distribution .…”

“…Advanced ex and in situ measurements have promoted fundamental understanding of the structural and morphological modifications alongw ith the effects of metal oxide composition on the conversion reaction features. [21,27,[30][31][32][33] Among the variousi nvestigative approaches, three-dimensional imaging at the micro-and nanoscale may actually shed light on the particle evolution throughout the lithium-exchange process and reveal crucial morphological parameters for electrode modelling, such as the phase volumef raction and the particle size distribution. [34][35][36] In particular, X-ray nano-computed tomography (CT) enablesadetailed reconstruction of the spatiald istribution of the various electrode components [37] and provides useful qualitative compositional information associated with the attenuation of the incident beam.…”

Self‐Assembled Porous NiFe2O4 Floral Microspheres Inlaid on Ultrathin Flake Graphite as Anode Materials for Lithium Ion Batteries

“…Comparing with various ferrites, NiFe 2 O 4 whose structure is defined to be inverse spinel, namely while all Ni 2+ and half Fe 3+ occupy the whole octahedral sites, another half Fe 3+ occupy the tetrahedral sites, shows more reactive sites with lithium ions during electrochemical process in compared with general spinels in terms of previous report by Chen et al ,. And both of this unique crystal form and the reaction mechanism in which Fe 3+ and Ni 2+ all take part in the electrochemical reaction showing as NiFe 2 O 4 +8 Li + +8 e − →Ni+2 Fe+4 Li 2 O↔NiO+Fe 2 O 3 +8 Li + +8 e − are involved and significantly contributed to the electrochemical performances . Besides, NiFe 2 O 4 possesses high theoretical capacity (915 mAh g −1 ).…”

Superexchange Effects on Oxygen Reduction Activity of Edge‐Sharing [CoxMn1−xO6] Octahedra in Spinel Oxide

“…Materials Synthesis and Characterizations : ZnCo x Mn 2− x O 4 spinel oxides were synthesized via a sol–gel, autocombustion method using citric acid as the chelating agent . The acetates of Zn, Co, and Mn mixed at the molar ratio of 1: x :2 − x , and citric acid, were dissolved in dilute nitric acid by stirring.…”