Design and synthesis of yolk-shell Fe 2 O 3 /N-doped carbon nanospindles with rich oxygen vacancies for robust lithium storage.

Ferric oxide (Fe 2 O 3 ) is an attractive anode material for lithium-ion batteries (LIBs) with a high theoretical capacity of 1005 mA h g -1 . However, its practical application is greatly restrained by the rapid capacity fading caused by the large volume expansion upon lithiation. To address this issue, we have designed and synthesized a unique yolk-shell Fe 2 O 3 /N-doped carbon hybrid structure (YS-Fe 2 O 3 @NC) with rich oxygen vacancies for robust lithium storage. The obtained results show that YS-Fe 2 O 3 @NC delivers a high reversible capacity of 578 mA h g -1 after 300 cycles at a current density of 5 A g -1 , about 11 times that (53.7 mA h g -1 ) of pristine Fe 2 O 3 . Furthermore, a high specific capacity of 300.5 mA h g -1 even at 10 A g -1 is achieved. The high reversible capacities, excellent rate capability and cycle stability of YS-Fe 2 O 3 @NC might be attributed to the elaborate yolk-shell nanoarchitecture. Moreover, electron percolation and a local built-in electric field induced by oxygen vacancies in the Fe 2 O 3 matrix could also enhance the kinetics of Li + insertion/deinsertion.