Core-shell ZnCo₂O₄@TiO₂ nanowall arrays as anodes for lithium ion batteries

In this paper ZnCo₂O₄ nanowall arrays (NWAs) were first obtained through self-assembly followed by calcination. Then atomic layer deposition was used to fabricate core-shell ZnCo₂O₄@TiO₂ NWAs as anode materials for lithium ion batteries (LIBs). The hierarchical NWA nanostructure has fast ion diffusion and electron transport at the electrode/electrolyte interface, while the excellent chemical stability of the TiO₂ shell can protect the ZnCo₂O₄ NWAs from volume expansion during the charge and discharge processes. The core-shell ZnCo₂O₄@TiO₂ core-shell NWAs composite is versatile as an anode material and exhibits enhanced electrochemical performance for LIBs. The initial capacity was 1598 mA h g^-1 (Coulombic efficiency reached 84.0%), and the reversible capacity after 90 cycles was 827 mA h g^-1 at a current density of 100 mA g^-1, showing high capacity and good cycling stability (much better than ZnCo₂O₄ NWAs). The ZnCo₂O₄@TiO₂ nanocomposite also showed excellent rate capability with a reversible capacity of 532 mA h g^-1 even at a current rate of 4500 mA g^-1. The encouraging experimental results suggest that the novel core-shell structure NWAs have great potential for practical applications in LIBs.