Fabrication of ordered macro-mesoporous single-crystalline Prussian blue and their derivatives for rechargeable sodium ion batteries

Abstract

Benefiting from their improved accessibility of active sites and accelerated ion diffusion processes, ordered macro-mesoporous materials have received substantial attention in energy storage fields. However, preparing ordered hierarchical porous materials with single-crystal nature remains a huge challenge. Herein, we successfully prepare ordered macro-mesoporous single-crystalline Fe-based Prussian blue (denoted as OMMS-Fe-HCF) by chelating-agent-assisted in-situ crystallization strategy within a three-dimensional (3D) ordered polystyrene spheres (PS) template interstice. Subsequently, 3D ordered macroporous iron diselenide@carbon hybrid tetradecahedron (denoted as 3DOM-FeSe2@C) is favorably prepared by in-situ selenization of the OMMS-Fe-HCF template. The resulting composite can commendably inherit and reserve the macroporous architecture and cubo-octahedron morphology of the precursor. In particular, FeSe2 nanoparticles are homogeneously encapsulated into the macroporous carbon matrix, significantly improving the mass transfer performance while maintaining the structural integrity. By virtue of hierarchical structure advantages and excellent conductivity, the 3DOM-FeSe2@C exhibits high-rate capability (361.6 mAh g−1 at 20 A g−1) and excellent cycling durability (306.4 mAh g−1 after 900 cycles at 2 A g−1) for sodium-ion batteries. Considering the rational design and accurate construction of OMMS-Fe-HCF, our work provides a new perspective on the preparation of such highly ordered macro-mesoporous composite for application in the energy storage fields.