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

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 Fe 2 O 3 shaped into dendritic nanostructure is locally in situ phase converted to FeS 2 and form porous Fe 2 O 3 /FeS 2 polycrystalline texture. The Fe 2 O 3 /FeS 2 maintains the original porous, cross-linked and low-dimension structural advantages of the Fe 2 O 3 precursor for electron transport and ions exchange and alleviating volume expansion. Then, the abundant heterogeneous in the converted Fe 2 O 3 /FeS 2 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 LiFePO 4 //Fe 2 O 3 /FeS 2 and (Na 3 V 2 (PO 4 ) 3 )//Fe 2 O 3 /FeS 2 full cells are successfully packaged and also show satisfactory electrochemical performances.