CoS2/NiS2 Nanocomposites Constructed by a Less-Liquid Reaction Strategy for High-Rate Mg2+/Li+ Hybrid Batteries

The design of a simple and safe method for constructing heterojunction structures in nanocomposites is a promising strategy for the manufacture of high-performance electrochemical energy storage devices. In this paper, based on the "less-liquid" reaction system and the assistance of the generated NaCl, a heterojunction-containing zero-dimensional (0 D) CoS2/NiS2 nanocomposite with particle sizes ranging from 50 to 200 nm were prepared. During this reaction, the reactant carries crystalline water to provide a liquid environment. Similarly, the lattice occupation of the generated NaCl promotes the construction of a large number of heterogeneous structures inside the nanostructured materials. The prepared material was subsequently employed as a cathode material for the Mg2+/Li+ hybrid battery (MLHB). The interface effect of the heterostructures induces an electric field within the nanocrystals, resulting in a lower ion diffusion resistance, and facilitating interfacial electron transport. Therefore, the heterojunctions accelerated the diffusion dynamics at the interface, and increased the charge-transfer rate. Mg2+ and Li+ exhibit reversible synergistic effects. More specifically, at a current density of 0.2 A g–1, the initial discharge specific capacity was 785.5 mAh g–1, while at a current density of 0.5 A g–1, a discharge specific capacity of 317.54 mAh g–1 was maintained over 200 cycles. And the Coulombic efficiency was maintained at ∼99.8%. This simple and safe design method for nanoscale heterogeneous materials provides a method for developing high-performance MLHB cathode materials.