Abstract
Transition metal dichalcogenides (TMDs) such as MoSe2 have continued to generate interest in the engineering community because of their unique layered morphology—the strong in-plane chemical bonding between transition metal atoms sandwiched between two chalcogen atoms and the weak physical attraction between adjacent TMD layers provides them with not only chemical versatility but also a range of electronic, optical, and chemical properties that can be unlocked upon exfoliation into individual TMD layers. Such a layered morphology is particularly suitable for ion intercalation as well as for conversion chemistry with alkali metal ions for electrochemical energy storage applications. Nonetheless, host of issues including fast capacity decay arising due to volume changes and from TMD’s degradation reaction with electrolyte at low discharge potentials have restricted use in commercial batteries. One approach to overcome barriers associated with TMDs’ chemical stability functionalization of TMD surfaces by chemically robust precursor-derived ceramics or PDC materials, such as silicon oxycarbide (SiOC). SiOC-functionalized TMDs have shown to curb capacity degradation in TMD and improve long term cycling as Li-ion battery (LIBs) electrodes. Herein, we report synthesis of such a composite in which MoSe2 nanosheets are in SiOC matrix in a self-standing fiber mat configuration. This was achieved via electrospinning of TMD nanosheets suspended in pre-ceramic polymer followed by high temperature pyrolysis. Morphology and chemical composition of synthesized material was established by use of electron microscopy and spectroscopic technique. When tested as LIB electrode, the SiOC/MoSe2 fiber mats showed improved cycling stability over neat MoSe2 and neat SiOC electrodes. The freestanding composite electrode delivered a high charge capacity of 586 mAh g−1electrode with an initial coulombic efficiency of 58%. The composite electrode also showed good cycling stability over SiOC fiber mat electrode for over 100 cycles.
Highlights
Introduction published maps and institutional affilThe most recent advancement in energy storage and conversion systems was the instigation of flexible or bendable systems that were fabricated to be portable, lightweight, and wearable while being mechanically flexible and having a high-energy density [1].the preparation methods, assembly process, and selection of proper electrolytes to transform traditional energy storage devices remains a challenging task
Compared to results in the literature, Wang et al found that the average diameter of the polyvinylidene fluoride (PVDF)/PVP nanofibers used in their experiment was in the range of 121–305 nm [10]
This work is the first to present MoSe2 nano-sheets combined with polymer-derived PVP/silicon oxycarbide (SiOC) fiber mats to yield a free-standing electrode, providing stable cycling in higher current densities in LIB half-cell configuration
Summary
Introduction published maps and institutional affilThe most recent advancement in energy storage and conversion systems was the instigation of flexible or bendable systems that were fabricated to be portable, lightweight, and wearable while being mechanically flexible and having a high-energy density [1].the preparation methods, assembly process, and selection of proper electrolytes to transform traditional energy storage devices remains a challenging task. LIBs usually consist of a carbon-based anode, a transition metal oxide-based cathode, a polymer separator, and an organic liquid electrolyte. In such devices, heavy metal foils are always used as both a conductive substrate and structural support with a slurry of active materials, binders, and conductive additives coated on its surface. Heavy metal foils are always used as both a conductive substrate and structural support with a slurry of active materials, binders, and conductive additives coated on its surface Such electrode designs have certain drawbacks—for example, as the metal foil possesses a smooth surface, the active materials can become detached from the current collector. There is an increase in the internal impedance and passivation of active materials due to iations
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