Epitaxial growth of hexahedral Fe2O3@SnO2 nano-heterostructure for improved lithium-ion batteries.

Abstract

Fe2O3 is one of the most important lithium storage materials and has attracted increasing interest owing to its good capacity in theory, abundant reserves, and better security. The utilization of Fe2O3 materials is hampered by their inferior cycle performance, low rate performance, and restricted composite variety. Herein, the heterostructure of Fe2O3@SnO2 with hexahedral structure was manufactured by two- step hydrothermal strategy, while the SnO2 nanopillars were epitaxially grown in six faces, not in the twelve edges of hexahedral Fe2O3 cubes, which comes from maximizing lattice matching on the six surfaces of Fe2O3. Furthermore, the experimental results prove that the hexahedral Fe2O3@SnO2 heterostructure exhibits remarkably enhanced electrochemical reversibility and reaction kinetics and delivers an impressive initial discharge capacity (1742 mA h g-1 at 4 A g-1), great rate performance (565 mA h g-1 at 5 A g-1), and stable long-term durability (661 mA h g-1 after 4000 cycles at 4 A g-1) as an anode for LIBs. The result of the finite element mechanical simulation further indicates that the SnO2 nanopillars grow on the six surfaces but not on the twelve edges of the hexahedral Fe2O3 cube, which would provide great rate performance and long-term stability. This study underlines the merits of the heterostructure and offers a useful design routine for superior electrode materials in LIBs.