Fe₂O₃/MoO₃@NG Heterostructure Enables High Pseudocapacitance and Fast Electrochemical Reaction Kinetics for Lithium-Ion Batteries

Transition metal oxides (TMOs) hold great potential for lithium-ion batteries (LIBs) on account of the high theoretical capacity. Unfortunately, the unfavorable volume expansion and low intrinsic electronic conductivity of TMOs lead to irreversible structural degradation, disordered particle agglomeration, and sluggish electrochemical reaction kinetics, which result in perishing rate capability and long-term stability. This work reports an Fe₂O₃/MoO₃@NG heterostructure composite for LIBs through the uniform growth of Fe₂O₃/MoO₃heterostructure quantum dots (HQDs) on the N-doped rGO (NG). Due to the synergistic effects of the "couple tree"-type heterostructures constructed by Fe₂O₃and MoO₃with NG, Fe₂O₃/MoO₃@NG delivers a prominent rate performance (322 mA h g^-1at 20 A g^-1, 5.0 times higher than that of Fe₂O₃@NG) and long-term cycle stability (433.5 mA h g^-1after 1700 cycles at 10 A g^-1). Theoretical calculations elucidate that the strong covalent Fe-O-Mo, Mo-N, and Fe-N bonds weaken the diffusion energy barrier and promote the Li⁺-ion reaction to Fe₂O₃/MoO₃@NG, thereby facilitating the structural stability, pseudocapacitance contribution, and electrochemical reaction kinetics. This work may provide a feasible strategy to promote the practical application of TMO-based LIBs.