Porous Fe₂O₃ nanorods anchored on nitrogen-doped graphenes and ultrathin Al₂O₃ coating by atomic layer deposition for long-lived lithium ion battery anode

Porous iron oxide (Fe₂O₃) nanorods anchored on nitrogen-doped graphene sheets (NGr) were synthesized by a one-step hydrothermal route. After a simple microwave treatment, the iron oxide and graphene composite (NGr-I-M) exhibits excellent electrochemical performances as an anode for lithium ion battery (LIB). A high reversible capacity of 1016 mAh g ^-1 can be reached at 0.1 A g^-1. When NGr-I-M electrode was further coated by 2 ALD cycles of ultrathin Al ₂O₃ film, the first cycle Coulombic efficiency (CE), rate performance and cycling stability of the coated electrode can be greatly improved. A stable capacity of 508 mAh g^-1 can be achieved at 2 A g^-1 for 200 cycles, and an impressive capacity of 249 mAh g^-1 at 20 A g^-1 can be maintained without capacity fading for 2000 cycles. The excellent electrochemical performance can be attributed to the synergy of porous iron oxide structures, nitrogen-doped graphene framework, and ultrathin Al ₂O₃ film coating. These results highlight the importance of a rational design of electrode materials improving ionic and electron transports, and potential of using ALD ultrathin coatings to mitigate capacity fading for ultrafast and long-life battery electrodes.