Comparative investigation of the performances of hematite nanoplates and nanograins in lithium-ion batteries

Abstract

In this work, we selectively prepared two samples with quite different nanocrystal shapes, i.e. nanoplates and nanograins but with almost identical surface areas to make a clear comparison of nanocrystal shapes on electrochemical performance. The electrochemical results indicate that the thinner hexagonal α-Fe₂O₃ nanoplates considerably enclosed by two larger (0001) basal surfaces exhibit higher capacity and stability than thicker α-Fe₂O₃ nanograins enclosed by a variety of crystal facets. During the conversion reaction, an orientated growth of porous nanostructure with orientated nanowalls as a stable framework is observed for the nanoplate, readily supplying a pathway for long and easy lithiation–delithiation cycling. The improved electrochemical performance of α-Fe₂O₃ nanoplates is surely related to the nanostructure with significantly stacked (0001) lattice planes along 〈0001〉 direction for orientated growth of γ-Fe₂O₃ nanodomains along one 〈111〉 direction.