Prussian blue analogs (PBA) derived porous bimetal (Mn, Fe) selenide with carbon nanotubes as anode materials for sodium and potassium ion batteries

The development of sodium/potassium-ion batteries with excellent performance would break the conflict between the limited lithium resources and low-price requirement of lithium-ion batteries. However, because of the bigger sizes of sodium/potassium ion in comparison to lithium ion, the requirement of anode materials with suitable structure for sodium/potassium ions insertion/extraction is still challenging. Here, porous MnSe/FeSe2 (Mn-Fe-Se) adhered/inserted with interlaced carbon nanotubes (CNTs) have been successfully designed and prepared via a simple chemical precipitation approach and a subsequent one-step carbonization-selenization of Mn-Fe Prussian blue analogs precursor process. Characterization results demonstrate that the prepared Mn-Fe-Se/CNTs with high conductive network architecture are constructed by Mn-Fe-Se sphere adhered/inserted with interlaced CNTs, each Mn-Fe-Se sphere is assembled using several tens of nanoparticles and numerous voids, and the individual nanoparticle is uniformly coated by a thin nitrogen-doped amorphous carbon layer. Due to such unique porous architecture and synergistic effect of the heterogeneous components, Mn-Fe-Se/CNTs anode possesses reversible sodium/potassium storage with excellent rate performance and prominent cycling stability. Furthermore, the sodium and potassium storage mechanisms and kinetics verify the fundamental principles of improved electrochemical performance. This study will shed light on the development of other metal selenides with interlaced carbon nanotubes for high-performance sodium/potassium-ion batteries and other energy storage equipment.