Phase transition of hollow-porous α-Fe₂O₃ microsphere based anodes for lithium ion batteries during high rate cycling

In the present paper, hollow-porous α-Fe₂O₃ microspheres are prepared via cation etching of zinc citrate microspheres and subsequent thermal treatment. The superior performance of the as-obtained α-Fe₂O₃ microspheres as an anode material for lithium ion batteries is evaluated. After 1000 cycles, the capacity still remains more than 1100 mA h g^-1 at a current rate of 1 A g^-1. Meanwhile, the crystal size induced phase transition of Fe₂O₃ microspheres (α → γ → β) is observed during cycling by the measurements of ex situ XRD and TEM, which is responsible for their abnormal performance fluctuation.