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

Abstract

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⁺/Co⁰ and Fe²⁺/Fe⁰. 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.