Assembly of CoFe2O4 Nanocrystals into Superparticles with Tunable Porosities for Use as Anode Materials for Lithium-Ion Batteries

Incorporating open architectures into a self-assembled close-packed superstructure is vital to its component exposure and hence the overall performance presented. Here, we depict a high-yield, emulsion-based assembly strategy that enables the one-step organization of preformed nanocrystals into crystalline superparticles with tunable macroporosity. We show that tuning the water/hexane ratio and/or the shearing rate during the emulsification process allows a wide-range modulation of the size and density of macropores generated within SPs. In addition, we demonstrate that the evolution of macroporosity, having negligible influence on the long-range ordering of nanocrystals, benefits the fast mass transport and superior electrochemical performance in the subsequent demonstrations for lithium storage. In addition to the single-component nanocrystals, this assembly route is also applicable to the fabrication of macroporous binary nanocrystal SPs.