Sulfur-Modified Carbon-Coated CoMoO₃ Nanohybrid Electrodes for Enhanced Lithium-Storage Capacity

Conversion-type binary cobalt-molybdenum oxides are rated as engineering lithium-ion battery (LIB) materials with high theoretical capacity. However, there exists an annoying issue regarding fast capacity fade because of the pulverization of the electrode induced by the intense volumetric expansion rate of these conversion-type materials. Reasonable micro/nanostructure design and structure protection are particularly important. In our work, a sulfur (S)-modified CoMoO₃/C electrode was designed through carbonization of the CoMoO₄-polydopamine precursor and later S modification. The carbon (C) layer can not only serve as a nice electroconductive network to stimulate the charge transfer but also serve as a rigid support to preserve the structural integrity. The facial S modification both generates numerous ultrathin MoS₂ nanosheets on the surface and provides plenty of electrolyte-accessible areas. Benefiting from the synergy of these components, such an S-modified CoMoO₃/C electrode is employed as a high-efficiency LIB anode, featured with fairly high capacity (861.3 mAh g^-1 at 0.1 A g^-1). Besides, such an electrode brings us a prominent capacity increase in the cycling process and finally reaches a superb retention of 99.7% after 500 cycles. This work expounds that the capacity promotion is attributed to restructuring of microarchitecture and the formation of more active sites, which guide us to optimize structure via the C-coating and S-modification routes.