Assembly of Multifunctional Ni<sub>2</sub>P/NiS<sub>0.66</sub> Heterostructures and Their Superstructure for High Lithium and Sodium Anodic Performance

The combination of structure designs at the microscopic and macroscopic level can efficiently enable electrode materials with greatly enhanced lithium and sodium storage. In this paper, the construction of Ni<sub>2</sub>P/NiS<sub>0.66</sub> heterostructures and their assembly into a superstructure at the nanoscale were successfully achieved by a facile and effective strategy. In the obtained superstructure, the Ni<sub>2</sub>P/NiS<sub>0.66</sub> heterostructures are homogeneously coated with ultrathin carbon layers (HT-NPS@C) and, at the same time, assembled into a yolk–shell nanosphere. Upon evaluation as the anode materials for Li-ion batteries, the HT-NPS@C delivers a high reversible capacity of 430 mA h g<sup>–1</sup> after 200 cycles at 200 mA g<sup>–1</sup> and ultrastable cyclability with negligible capacity loss over 500 cycles. Furthermore, the coin-type full cell with the LiNi<sub>1/3</sub>Co<sub>1/3</sub>Mn<sub>1/3</sub>O<sub>2</sub> (LNCMO) cathode and HT-NPS@C anode deliver a high specific capacity of 323.5 mA h g<sup>–1</sup> after 50 cycles at 0.3 A g<sup>–1</sup>. Apart from an excellent performance as promising anode materials for LIBs (Li-ion batteries), the Na-ion batteries with HT-NPS@C sphere electrodes also manifest a remarkable electrochemical performance.