Mesoporous carbons and Fe collectively boost the capacity increases upon Long-term cycling of Ni/Fe/NiFe2O4@C anode for Lithium-ion batteries

In this study, Ni/Fe/NiFe2O4@C composites (60 % of C) are fabricated by the decorations of NiFe2O4 nanorods onto mesoporous carbons with the excellent cycling stability and high rate performance as LIBs anode. The capacity increase behaviors upon long-term cycling are observed within Ni/Fe/NiFe2O4@C electrodes, where the specific capacity increases from 598.5 mAh g−1 at the first dozen cycles up to the maximum value close to 1100 mA g−1 after 1000 cycles at 5 A g−1. A series of ex-situ and in-situ characterizations are subsequently performed on Ni/Fe/NiFe2O4@C electrodes upon long-term cycling to understand the nature underlying the evolution processes. The reconstructions of both surface SEI layer and NiFe2O4 nanorods within Ni/Fe/NiFe2O4@C electrode are demonstrated to provide much more pathways and shorten distances for rapid ion diffusions and electron transmissions, collectively resulting that much more mesoporous carbons (MC) below NiFe2O4 nanorods can be exposed to storage lithium ions together with the increased capacity and high rate performance. In addition, the outer organic layer formed on electrode surfaces can accommodate the electrode volume expansion accompanied with the extraordinarily excellent long-term cycling electrochemical performances.