Zeolitic imidazolate framework/Prussian blue analogue derived CoSe₂/FeSe₂ heterostructure for long-cycle aluminum-ion batteries

Aluminum-ion batteries (AIBs) have been considered a low-cost, safe and high energy density candidate for large-scale electrochemical energy storage systems. Here, we utilize the concept of interface engineering to synthesize a CoSe2/FeSe2 heterostructure cathode through MOF-on-MOF heteroepitaxial growth. The presence of an internal electric field between the CoSe2 and FeSe2 phases induces a synergistic effect to achieve rapid charge transfer and ion diffusion, which enables a facile conversion reaction based on Co2+/Co-0 and Fe2+/Fe-0. The CoSe2/FeSe2 heterostructure displays an initial discharge capacity of 356.9 mA h g(-1) at 100 mA g(-1). After 1600 cycles at 200 mA g(-1), the reversible capacity is 133.7 mA g(-1). Theoretical calculation also demonstrates that the designed CoSe2/FeSe2 heterostructure can significantly promote the directional electron transfer and reduce the aluminum-ion migration barrier energy. Therefore, the concept of heterostructure cathodes provides a strategy to develop long-cycle life AIBs.