Synthesis of Fe3Se4/CoFe/NSeC@NSeC for fast and longevous energy storage

The applications of metal chalcogenides in Li/Na-ion storage are limited by their low intrinsic conductivity and structure pulverization, which result in capacity reduction and low-rate performance. To overcome these limitations, herein, a core-shell box structure consisting of Fe3Se4 and Co7Fe3 alloying compound integrated with N, Se-doped carbon core and N, Se-doped carbon shell (denoted as Fe3Se4/CoFe/[email protected]) is fabricated successfully using an initial selenization/carbonization and subsequent thermal induction strategy of the corresponding hollow CoFe-Prussian Blue analogue box precursor. The possible formation mechanism of Fe3Se4/CoFe/[email protected] is proposed. The core-shell Fe3Se4/CoFe/[email protected] with the void space can accommodate the volume expansion and facilitate Li+/Na+ dissolusion on cycling, while the resulting Co7Fe3 alloy compound and NSeC can synergistically accelerate the conductivity of the electrode material from local and overall aspects for rapid electron and ion transportation. As a result, the Fe3Se4/CoFe/[email protected] box anode exhibits superior electrochemical performance in both LIBs and SIBs, such as a reversible specific capacity of 976.6 mAh g−1 at 0.2 A g−1 and even 782.5 mAh g−1 at 1 A g−1 for LIBs, and 324 mAh g−1 at 0.2 A g−1 for SIBs, respectively. The improved Li/Na storage properties of the composite demonstrate the significance of meticulously constructing novel multicomponent hierarchical structures with higher complexity.