Rational design of NiFe₂O₄-rGO by tuning the compositional chemistry and its enhanced performance for a Li-ion battery anode

A facile in situ hydrothermal route is adopted for the synthesis of NiFe₂O₄-reduced graphene oxide (NiFe₂O₄-rGO) which is verified as a promising high-property anode material for Li-ion batteries. The formation of NiFe₂O₄ and the reduction of GO occur simultaneously. Ultrafine NiFe₂O₄ nanocrystals (below 10 nm) disperse uniformly and are immobilized by the reduced graphene oxide. The electrochemical tests show that NiFe₂O₄-rGO exhibits a high specific capacity of 1129 mA h g^-1 at 0.2 A g^-1 after ∼300 discharge-charge cycles. The excellent electrochemical properties are mainly ascribed to the introduction of the graphene matrix which offers two-dimensional conductive networks for fast electron transfer and buffers the stress from volume expansion during charge-discharge cycles. Moreover, the NiFe₂O₄ nanocrystals as the spacers inhibit the aggregation of rGO and form the stacking pore. More importantly, the well-designed heterostructures and the synergistic effects between NiFe₂O₄ and rGO can enhance the transport of Li⁺ and electrons and improve the structural stability of the anode, thereby enhancing the electrochemical properties. Our work not only provides an attractive strategy for the design of a hierarchical composite, but also offers a strategy for a promising anode material.