Hierarchical heterostructures of NiO nanosheet arrays grown on pine twig-like Β-NiS@Ni₃S₂ frameworks as free-standing integrated anode for high-performance lithium-ion batteries

Electroactive 3D conductive collectors of β-NiS@Ni₃S₂ are obtained from the in-situ conversion of Ni foams and exhibit unique hierarchical pine twig-like microstructure, in which the β-NiS nanorod arrays are uniformly supported on hollow Ni₃S₂ skeletons. Then the mesoporous NiO nanosheet arrays are grown successfully on the surface of β-NiS nanorods via a facile hydrothermal method and the following calcination, forming hierarchical NiO@β-NiS@Ni₃S₂ composites. When directly used as anodes for lithium-ion batteries (LIBs), the obtained composites deliver superior lithium storage properties with a considerable reversible capacity of 498.5 mAh g⁻¹ (calculated by the mass of the whole anode including substrate) after 100 cycles and excellent rate capability, holding a great promise as free-standing integrated anodes for high-performance LIBs. The remarkable electrochemical performance could be attributed to the well-designed 3D hierarchical heterostructures and the synergy effect from the integration of NiO, β-NiS and Ni₃S₂. Importantly, the β-NiS@Ni₃S₂ conductive collectors also possess electrochemical activity and make a significant contribution in lithium storage.