Heterogeneous triple-shelled TiO2@NiCo2O4@Co3O4 nanocages as improved performance anodes for lithium-ion batteries

ZIF-67-derived NiCo2O4@Co3O4 double-shelled nanocages was coated by a layer of TiO2 shell, forming a heterogeneous triple-shelled cage-in-cage structure. As-synthesized triple-shelled nanocages were characterized by XRD, SEM and TEM. As anode materials for lithium ion batteries, triple-shelled nanocages show improved cycling stability and discharge capacity, which could be due to the cage-in-cage hollow nanostructure and beneficial effect of the TiO2 shell.