Heterointerface Engineered Core-Shell Fe2O3@TiO2 for High-Performance Lithium-Ion Storage

Abstract

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.

Figure 1

Characterization of Fe₂O₃@TiO₂ heterostructure: (a) XRD patterns; (b–i) TEM, SAED, and HRTEM images; (j) XPS survey spectrum and high-resolution XPS survey spectra of (k) Fe 2p orbital, (l) Ti 2p orbital, and (m) O 1s orbital.

Figure 2

(a) Crystal structure image of α-Fe₂O₃. Electrochemical properties of Fe₂O₃ as anode material for LIBs: (b) CV curves at a scan rate of 0.1 mV s⁻¹; (c) cycling performance at a current density of 0.1 A g⁻¹, (d) GCD curves, (e) capacity retention and linear fit curve; (f) rate performance from 0.1 A g⁻¹ to 4.0 A g⁻¹.

Figure 3

(a) Crystal structure image of anatase-TiO₂. Electrochemical properties of TiO₂ as anode material for LIBs: (b) CV curves at a scan rate of 0.1 mV s⁻¹; (c) cycling performance at a current density of 0.1 A g⁻¹, (d) GCD curves, (e) capacity retention and fitted linear curve; (f) rate performance from 0.1 A g⁻¹ to 4.0 A g⁻¹.

Figure 4

(a) Model image of half-cell. Electrochemical properties of Fe₂O₃@TiO₂ heterostructure as anode material for LIBs: (b) CV curves at a scan rate of 0.1 mV s⁻¹; (c) cycling performance at a current density of 0.1 A g⁻¹, (d) GCD curves, (e) capacity retention and fitted linear curve; (f) rate performance from 0.1 A g⁻¹ to 4.0 A g⁻¹.

Figure 5

(a) CV curves of Fe₂O₃@TiO₂ heterostructure at different scan rates from 0.1 to 1.0 mV s⁻¹; (b) the b-values of corresponding oxidation peaks and reduction peaks; (c) area ratio image of pseudocapacitance at 1.0 mV s⁻¹; (d) ratio image of pseudocapacitance contribution at different scan rates from 0.1 to 1.0 mV s⁻¹.