Interfacial engineering of graphene aerogel encapsulated FeSe2-Fe2O3 heterojunction nanotubes for enhanced lithium storage

Heterointerface engineering has been proved to be an effective strategy to improve the electrochemical performances of electrode materials by overcoming inherent drawbacks of single phase electrode. However, the rational construction of heterogeneous composite with abundant heterogeneous interfaces for lithium-ion batteries (LIBs) remains a great challenge. Herein, graphene aerogel encapsulated FeSe 2 -Fe 2 O 3 heterojunction nanotubes (FeSe 2 -Fe 2 O 3 @GA) with inner-outer bi-interfacial structures were fabricated by freeze-drying method and partial selenization treatment. The built-in electric fields induced on the FeSe 2 -Fe 2 O 3 could greatly lower the activation energy for rapid charge transfer kinetics. And GA as outer surface not only could maintain the integrity of active material structure, but also enhance its electronic conductivity. Benefiting from these advantages, the FeSe 2 -Fe 2 O 3 @GA anode exhibits an improved electrochemical performance in term of lithium storage capacity (1515.6 mAh g -1 at 0.2 A g -1 ), cycle stability and high rate capability (492.7 mAh g -1 after 600 cycles at 1 A g -1 ). The kinetics analysis and theoretical calculation also interpret the significant role of heterointerface engineering construction in improving the reaction kinetics of lithium storage. The graphene aerogel encapsulated FeSe 2 -Fe 2 O 3 nanotube heterojunctions (FeSe 2 -Fe 2 O 3 @GA) with inner-outer bi-interfacial structures behaves the improvement of electric conductivity and structural stability and reduces ion diffusion barrier, resulting in an enhanced electrochemical performance in term of lithium storage capacity, cycle stability and high rate capability. • FeSe 2 -Fe 2 O 3 heterojunction nanotubes encapsulated in graphene aerogel (FeSe 2 -Fe 2 O 3 @GA) were fabricated. • The 1D hollow porous nanotube could facilitate the electrolyte penetration for shortening Li + diffusion path. • The GA could maintain the integrity of active material structure, and enhance its electronic conductivity. • The built-in electric fields could lower the activation energy for rapid charge transfer kinetics. • The FeSe 2 -Fe 2 O 3 @GA anode exhibits improved electrochemical performances.