Solvent-Exchange Strategy toward Aqueous Dispersible MoS2 Nanosheets and Their Nitrogen-Rich Carbon Sphere Nanocomposites for Efficient Lithium/Sodium Ion Storage.

Major challenges in developing 2D transition-metal disulfides (TMDs) as anode materials for lithium/sodium ion batteries (LIBs/SIBs) lie in rational design and targeted synthesis of TMD-based nanocomposite structures with precisely controlled ion and electron transport. Herein, a general and scalable solvent-exchange strategy is presented for uniform dispersion of few-layer MoS2 (f-MoS2 ) from high-boiling-point solvents (N-methyl-2-pyrrolidone (NMP), N,N-dimethyl formaldehyde (DMF), etc.) into low-boiling-point solvents (water, ethanol, etc.). The solvent-exchange strategy dramatically simplifies high-yield production of dispersible MoS2 nanosheets as well as facilitates subsequent decoration of MoS2 for various applications. As a demonstration, MoS2 -decorated nitrogen-rich carbon spheres (MoS2 -NCS) are prepared via in situ growth of polypyrrole and subsequent pyrolysis. Benefiting from its ultrathin feature, largely exposed active surface, highly conductive framework and excellent structural integrity, the 2D core-shell architecture of MoS2 -NCS exhibits an outstanding reversible capacity and excellent cycling performance, achieving high initial discharge capacity of 1087.5 and 508.6 mA h g-1 at 0.1 A g-1 , capacity retentions of 95.6% and 94.2% after 500 and 250 charge/discharge cycles at 1 A g-1 , for lithium/sodium ion storages, respectively.