Heterointerface Engineered Core-Shell FeO@TiO for High-Performance Lithium-Ion Storage.

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 (FeO@TiO) 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 FeO@TiO delivers a remarkable discharge capacity of 1342 mAh g and an extraordinary capacity retention of 82.7% at 0.1 A g after 300 cycles. FeO@TiO shows an excellent rate performance from 0.1 A g to 4.0 A g. Further, the discharge capacity of FeO@TiO reached 736 mAh g at 1.0 A g 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 FeO@TiO 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.