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

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.