NiS2 nanoparticles by the NaCl-assisted less-liquid reaction system for the magnesium-ion battery cathode.

Rechargeable magnesium batteries are expected to be the next generation of energy storage devices. Therefore, it is of great significance to develop low-cost and long-life magnesium (Mg) electrode materials. However, the traditional method of synthesizing electrode materials is complicated, and it is difficult to remove potentially dangerous impurities. In this study, without adding any additional solvent, the crystal water in the reactant provides a liquid environment directly for the reaction, such that the whole reaction could be carried out safely and efficiently in the less liquid reaction system. Furthermore, NiS2 in the cotton-like form was synthesized under the spatial effect of NaCl solution in a confined space. The fabricated material was tightly connected and has abundant active sites, which promote the rapid transport of charge. This work provides a general strategy of preparation methods for metal sulfides and also points in a new direction for the improvement of electrochemical performance with less-liquid reaction systems without additional solvents.

In Situ Anchoring Anion-Rich and Multi-Cavity NiS2 Nanoparticles on NCNTs for Advanced Magnesium-Ion Batteries.

Magnesium (Mg)-ion batteries with low cost and good safety characteristics has attracted a great deal of attention recently. However, the high polarity and the slow diffusion of Mg2+ in the cathode material limit the development of practical Mg cathode materials. In this paper, an anion-rich electrode material, NiS2 , and its composite with Ni-based carbon nanotubes (NiS2 /NCNTs) are explored as the cathode materials for Mg-ion batteries. These NiS2 /NCNTs with excellent Mg2+ storage property is synthesized by a simple in situ growth of NiS2 nanoparticles on NCNTs. NiS2 with both a large regular cavity structure and abundant sulfur-sulfur (SS) bonds with high electronegativity can provide a large number of active sites and unobstructed transport paths for the insertion-disinsertion of Mg2+ . With the aid of 3D NCNTs skeleton as the transport channel of the electron, the NiS2 /NCNTs exhibit a high capacity of 244.5 mAh g-1 at 50 mA g-1 and an outstanding rate performance (94.7 mAh g-1 at 1000 mA g-1 ). It achieves capacitance retention of 58% after 2000 cycles at 200 mA g-1 . Through theoretical density functional theory (DFT) calculations and a series of systematic ex situ characterizations, the magnesiation/demagnesiation mechanisms of NiS2 and NiS2 /NCNTs and are elucidated for fundamental understanding.