The pursuit of sustainable and cost-effective energy storage systems has intensified research into sodium-ion batteries (SIBs), which offer a viable alternative to lithium-ion batteries by leveraging abundant raw materials. Among various anode candidates, molybdenum disulfide (MoS₂) stands out due to its high theoretical capacity and favorable interlayer spacing for sodium ion insertion. However, its practical implementation is limited by low intrinsic conductivity, significant volume changes during cycling, and irreversible phase transformations that degrade performance over time. To overcome these challenges, this study introduces a novel hierarchically structured core-shell composite: nitrogen-doped MoS₂/carbon encapsulated within a nanoscale silicon oxycarbide (SiOC) shell, designated as N-MoS₂/C@SiOC.

The synthesis process begins with the in situ formation of an amorphous nitrogen-doped MoS₂/polyfurfural precursor through a self-catalyzed reaction between MoCl₅, thioacetamide, and furfural in ethanol. This precursor is then dispersed in silicone oil via ultrasonication and stirring, enabling uniform coating through hydrogen bonding between hydroxyl groups in polyfurfural and siloxane moieties in silicone oil. The mixture undergoes a two-step thermal treatment: first at 500 °C to initiate cross-linking between silicone oil and divinylbenzene, forming a preceramic polymer layer; then at 900 °C to simultaneously carbonize the organic components, crystallize MoS₂, and convert the preceramic matrix into SiOC ceramic. The resulting spherical composite particles exhibit a core-shell architecture with a well-defined interface, confirmed by FE-SEM, TEM, and HR-TEM analyses. The SiOC shell thickness is approximately 10 nm, and the interlayer spacing of the MoS₂ core expands from 6.2 Å to 6.6 Å due to nitrogen doping, verified by XRD and high-resolution imaging.

This hierarchical design confers multiple functional advantages. Nitrogen incorporation enhances electronic conductivity and stabilizes the MoS₂ structure, facilitating rapid sodium-ion diffusion. The carbon framework derived from polyfurfural improves charge transport and mechanical resilience. The SiOC shell plays a critical multifunctional role: it acts as a robust, elastic buffer that mitigates mechanical stress caused by repeated volume expansion (~39.8% without shell vs. ~26.9% with shell), prevents electrolyte penetration, suppresses side reactions, and provides additional capacitive storage sites due to its mesoporous nature. Electrochemical evaluation reveals exceptional performance: the N-MoS₂/C@SiOC electrode delivers a reversible capacity of 540.7 mAh g⁻¹, exhibits near-100% capacity retention after 200 cycles (127.9%), and maintains 54.7% of its initial capacity even at ultra-high current densities of 10 A g⁻¹. In contrast, bulk MoS₂ and non-coated N-MoS₂/C composites show rapid degradation and poor rate capability.

Cyclic voltammetry and galvanostatic charge-discharge profiles confirm highly reversible conversion reactions and efficient Na⁺ insertion/extraction.PANK2 Antibody manufacturer The initial Coulombic efficiency of 75.Diclosulam medchemexpress 5% is slightly lower than that of uncoated samples, primarily due to SEI formation and minor irreversible reactions involving oxygen in the SiOC shell—yet this trade-off is outweighed by superior long-term stability.PMID:35141975 EIS analysis shows significantly reduced charge-transfer resistance in the coated electrode after prolonged cycling, indicating enhanced interfacial stability. Post-cycling microscopy reveals no cracking or delamination in the N-MoS₂/C@SiOC electrode, whereas the uncoated counterpart suffers severe structural damage and MoO₃ phase formation.

Furthermore, kinetic analysis based on CV scans at varying rates demonstrates that the N-MoS₂/C@SiOC electrode follows a predominantly capacitive mechanism, with capacitive contribution increasing from 74.8% to 92.5% as scan rate rises—attributed to the large surface area and mesoporosity of the SiOC shell. This enables fast adsorption-desorption processes essential for high-rate performance. The combination of expanded interlayer spacing, conductive network, and protective SiOC layer results in a synergistic enhancement of both kinetics and durability.

In conclusion, the developed N-MoS₂/C@SiOC core-shell heterostructure represents a breakthrough in anode design for sodium-ion batteries. By integrating nitrogen doping, carbon integration, and a multifunctional SiOC coating in a single, scalable synthesis route, this material achieves outstanding capacity, exceptional cycle life, and superior rate performance. Its rational design principles are broadly applicable to other high-capacity conversion or alloying anodes, offering a promising pathway toward next-generation energy storage devices with high energy density, long lifespan, and economic feasibility.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com