Epitaxial growth of hexahedral Fe 2 O 3 @SnO 2 nano-heterostructure for improved lithium-ion batteries.

Fe 2 O 3 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 Fe 2 O 3 materials is hampered by their inferior cycle performance, low rate performance, and restricted composite variety. Herein, the heterostructure of Fe 2 O 3 @SnO 2 with hexahedral structure was manufactured by two- step hydrothermal strategy, while the SnO 2 nanopillars were epitaxially grown in six faces, not in the twelve edges of hexahedral Fe 2 O 3 cubes, which comes from maximizing lattice matching on the six surfaces of Fe 2 O 3 . Furthermore, the experimental results prove that the hexahedral Fe 2 O 3 @SnO 2 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 SnO 2 nanopillars grow on the six surfaces but not on the twelve edges of the hexahedral Fe 2 O 3 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.