Booting the electrochemical properties of Fe-based anode by the formation multiphasic nanocomposite for lithium-ion batteries

Fe-based compounds with good environmental friendliness and high reversible capacity have attracted considerable attention as anode for lithium-ion batteries. But, similar to other transition metal oxides (TMOs), it is also affected by large volume changes and inferior kinetics during redox reactions, resulting in the destruction of the crystal structure and poor electrochemical performance. Here, Fe₃O₄/C nanospheres anchored on the two-dimensional graphene oxide as precursors are phosphated and sintered to build the multiphasic nanocomposite. XRD results confirmed the multiphasic nanocomposite composed of Fe₂O₃, Fe₃O₄ and Fe₃PO₇, which will facilitate the Li⁺ diffusion. And the carbonaceous matrix will buffer the volume changes and enhance electron conduction. Consequently, the multiphasic Fe-based anode delivers a large specific capacity of 1086 mAh/g with a high initial Coulombic efficiency of 87% at 0.1 C. It also has excellent cycling stability and rate property, maintaining a capacity retention of ～87% after 300 cycles and a high reversible capacity of 632 mAh/g at 10 C. The proposed multiphasic structure offers a new insight into improving the electrochemical properties of TMO-based anodes for advanced alkali-ion batteries.