Preparing an MnS@CN composite with lasagna-like nanostructure through pyrolysis of an organic hybrid manganese sulfide for electrochemical lithium storage.

Abstract

Carbon-coupled metal sulfide composites with rational nanostructures could be used as ideal anode materials for lithium ion batteries (LIBs). Herein, we solvothermally synthesized a crystalline organic hybrid manganese sulfide Mn(phen)2S6 (phen = 1,10-phenanthroline). Its structure featured an Mn(phen)2S6 molecule, in which the Mn atom was coordinated with two phen ligands and an S6 chain. The coordination between the Mn atom and phen/S6 ligands highlighted the potential of Mn(phen)2S6 as a precursor for synthesizing a carbon-coupled MnS composite via thermal treatment. After pyrolyzing Mn(phen)2S6 at 500 °C, an MnS@CN (CN = nitrogen-doped carbon) composite was generated. In particular, the MnS@CN composite possessed a lasagna-like nanostructure with MnS nanoparticles encapsulated in the interlayers of the nitrogen-doped carbon nanosheets. The lasagna-like nanostructure of MnS@CN promoted the charge transport and lithium-ion diffusion kinetics while also providing buffer space for the volume fluctuations of MnS nanoparticles during lithiation/delithiation. Owing to these advantages, MnS@CN offered an initial capacity of 680.7 mAh g-1 at 500 mA g-1, which was much higher than that of pure MnS (249.1 mAh g-1). Moreover, after 500 cycles, MnS@CN exhibited a capacity retention of 97.8%, which was also higher than that of pure MnS (34.1%). Thus, our study shows the potential of organic hybrid metal sulfides as precursors for preparing carbon-coupled metal sulfide composites with unique nanostructures for electrochemical lithium storage.