The rational design of the heterogeneous interfaces enables precise adjustment of the electronic structure and optimization of the kinetics for electron/ion migration in energy storage materials. In this work, the built-in electric field is introduced to the iron-based anode material (Fe2O3@TiO2) through the well-designed heterostructure. This model serves as an ideal platform for comprehending the atomic-level optimization of electron transfer in advanced lithium-ion batteries (LIBs). As a result, the core-shell Fe2O3@TiO2 delivers a remarkable discharge capacity of 1342 mAh g-1 and an extraordinary capacity retention of 82.7% at 0.1 A g-1 after 300 cycles. Fe2O3@TiO2 shows an excellent rate performance from 0.1 A g-1 to 4.0 A g-1. Further, the discharge capacity of Fe2O3@TiO2 reached 736 mAh g-1 at 1.0 A g-1 after 2000 cycles, and the corresponding capacity retention is 83.62%. The heterostructure forms a conventional p-n junction, successfully constructing the built-in electric field and lithium-ion reservoir. The kinetic analysis demonstrates that Fe2O3@TiO2 displays high pseudocapacitance behavior (77.8%) and fast lithium-ion reaction kinetics. The capability of heterointerface engineering to optimize electrochemical reaction kinetics offers novel insights for constructing high-performance iron-based anodes for LIBs.
Keywords: built-in electric field; electrochemical kinetics; heterointerface engineering; iron-based anode; lithium-ion storage.