In Situ Phase Transformation of Nanoporous Fe2O3 Dendrite to Fe2O3/FeS2 Polycrystalline Texture Achieving Superior Rate Capability and Ultra-Long Cycling Stability with High Capacity.

Abstract

Structural design combined with crystal engineering is an external and internal modifying strategy for metal oxides and sulfides as anode materials for lithium/sodium-ion batteries (LIBs/SIBs). In this paper, the low-cost iron-based oxide of Fe₂O₃ shaped into dendritic nanostructure is locally in situ phase converted to FeS₂ and form porous Fe₂O₃/FeS₂ polycrystalline texture. The Fe₂O₃/FeS₂ maintains the original porous, cross-linked and low-dimension structural advantages of the Fe₂O₃ precursor for electron transport and ions exchange and alleviating volume expansion. Then, the abundant heterogeneous in the converted Fe₂O₃/FeS₂ dramatically enhances electron diffusion in crystal and the structural stability at phase boundary. The prepared anode achieves superior rate capability and ultra-long cycling stability with high capacity both in LIBs and SIBs. Specially, it shows 1017 and 1016 mAh g^-1 at 10 A g^-1 in LIBs and SIBs, separately. After 3000 cycles, the electrodes maintain 266 mAh g^-1 at 10 A g^-1 in LIBs and 279 mAh g^-1 in SIBs. In addition, the LiFePO₄//Fe₂O₃/FeS₂ and (Na₃V₂(PO₄)₃)//Fe₂O₃/FeS₂ full cells are successfully packaged and also show satisfactory electrochemical performances.