Converting Prussian blue to porous cubic Fe3O4/nitrogen-doped carbon nanocomposite through a space-confined calcination strategy for high lithium storage anodes

Prussian blue is usually used to be precursor to prepare nanosized cubic iron oxides due to its well-defined cube morphology, but the as-prepared iron oxides need to be extral coated with carbon otherwise their lithium storage performance is not satisfactory. Moreover, during preparation of the iron oxides not only the carbon-rich CN– group of the Prussian blue is wasted, but also the resulting gas derived from the decomposition of the CN– is bad for environment. Therefore, it will be significant if the CN– can be converted into N-doped carbon directly. Herein, we develop a novel space-confined calcination strategy to directly convert Prussian blue to Fe3O4/nitrogen-doped carbon (N-C) nanocube composite, in which the interconnected Fe3O4 nanoparticles are in-situ embedded within a porous cubic N-C matrix. The as-prepared composite, therefore, integrates the structural advantages of Fe3O4 nanoparticles, porous cubic nanostructure, and N-doped carbon, which guarantee its excellent structure stability and enhanced electrochemical kinetics during cycling process. As a result, this composite exhibits outstanding performance, including high capacity, long life and good rate, with 785 mA h g−1 at 200 mA g−1 after 350 cycles and 705 mA h g−1 at 1000 mA g−1 after 600 cycles.