Lithium-sulfur batteries (LSBs) are emerging as a promising next-generation energy storage technology due to their high theoretical energy density of 2600 Wh kg⁻¹, low cost, and environmental friendliness. However, practical implementation faces significant challenges including poor sulfur utilization, sluggish redox kinetics, and the notorious lithium polysulfide (LiPS) shuttle effect. To address these issues, a multifunctional Ag/VN@Co/NCNT nanocomposite has been developed as a hierarchical nanoreactor-based sulfur host. This architecture integrates multiple adsorption and catalytic sites within a well-designed nanostructure. The core consists of heterostructured Ag/VN nanorods that serve as a highly conductive backbone, providing internal catalytic and adsorption sites for LiPS conversion. These nanorods are wrapped with interconnected nitrogen-doped carbon nanotubes (NCNTs), which are in situ grown from the Ag/VN surface, significantly enhancing the specific surface area for sulfur dispersion and buffering volume changes during cycling. At the tips of the NCNTs, Co nanoparticles act as outer adsorption sites, capturing escaped LiPS and effectively suppressing the shuttle effect. The synergistic interplay between the internal Ag/VN catalysts and external Co/NCNTs creates a dual-layered confinement system that not only physically traps LiPS but also accelerates their electrochemical conversion into insoluble Li₂S₂/Li₂S. Electrochemical testing confirms exceptional performance: the Ag/VN@Co/NCNTs@S cathode delivers a remarkable rate capability of 609.7 mAh g⁻¹ at 4 C and maintains a capacity decay of only 0.018% per cycle over 2000 cycles at 2 C. This outstanding stability and high-rate performance demonstrate the effectiveness of the hierarchical design in mitigating key degradation mechanisms. The combination of strong chemical adsorption, efficient electron transfer, and rapid catalytic conversion enables this material to overcome long-standing limitations in LSBs, bringing them closer to real-world applications.
Enhanced Sulfur Utilization through Multifunctional Hierarchical Design
The development of advanced sulfur hosts is critical for unlocking the full potential of lithium-sulfur batteries. In this study, a hierarchical Ag/VN@Co/NCNT nanocomposite was engineered to simultaneously address sulfur insulating properties, volume expansion, and polysulfide shuttling. The synthesis begins with -AgVO₃ nanowires, which are coated with ZIF-67 and then subjected to annealing under a reducing atmosphere. During this process, the inner -AgVO₃ is reduced to Ag/VN nanorods, while the outer ZIF-67 transforms into interwoven NCNTs decorated with Co nanoparticles. The resulting structure features a unique three-level organization: the conductive Ag/VN core facilitates electron transport; the NCNT network provides high surface area and mechanical flexibility; and the Co nanoparticles at the tips offer additional adsorption capacity. Characterization techniques such as SEM, TEM, HRTEM, and EDS confirm the successful integration of all components and their spatial distribution. XRD analysis verifies the crystalline phases of VN, Co, and Ag, while XPS reveals the presence of various nitrogen species and oxidation states of V and Co, indicating favorable surface chemistry for LiPS interaction.CD2 Antibody Epigenetic Reader Domain Raman spectroscopy shows a higher ID/IG ratio in Ag/VN@Co/NCNTs compared to reference materials, suggesting increased defect density beneficial for catalysis. BET measurements indicate a moderate specific surface area of 80.7 m² g⁻¹, with dominant mesoporosity contributing to effective mass transport. After sulfur infiltration via melt diffusion, uniform sulfur distribution is confirmed by EDX mapping and XRD, with sulfur content quantified at 71.8 wt%. The hierarchical structure ensures excellent sulfur confinement and dispersion, laying the foundation for high active material utilization.
Synergistic Adsorption and Catalytic Effects in Polysulfide Management
A key innovation in this work lies in the synergistic functionality of the hierarchical nanoreactor. The Ag/VN@Co/NCNTs composite exhibits superior LiPS adsorption capacity, demonstrated by UV-vis spectroscopy showing complete removal of Li₂S₆ from solution after 12 hours, unlike other tested materials. XPS analysis reveals clear shifts in binding energies of Ag, Co, and V upon LiPS exposure, confirming strong chemical interactions. DFT calculations further support this, showing adsorption energies of -2.8 eV for Ag/VN and -4.2 eV for Co—significantly stronger than pure VN (-1.6 eV). This indicates that the heterojunction enhances adsorption, while Co provides the strongest affinity. The multi-site nature of the system allows for sequential capture: LiPS are first adsorbed by the Ag/VN interface, then further trapped by Co nanoparticles at the NCNT tips. This dual-layer mechanism prevents both initial dissolution and subsequent diffusion. Moreover, the catalytic activity is crucial for converting soluble LiPS into solid products. CV profiles show that the Ag/VN@Co/NCNTs@S electrode exhibits the highest reduction peak potential (2.03 V vs. 1.97–2.02 V for others), indicating lower activation energy for the LiPS conversion reaction. The Q₂/Q₁ ratio of 2.33 surpasses those of control samples, confirming enhanced catalytic efficiency. Ex situ Raman spectroscopy tracks the disappearance of S₈ and mid-chain LiPS peaks during discharge, verifying complete conversion.CaMKIV Antibody References Potentiostatic tests reveal faster Li₂S nucleation onset (1010 s) and higher dissolution capacity (776.PMID:34809527 8 mAh g⁻¹), demonstrating accelerated redox kinetics. Together, these results prove that the hierarchical design enables effective physical confinement combined with powerful chemical catalysis, drastically improving LiPS management.
Outstanding Electrochemical Performance and Long-Term Stability
The Ag/VN@Co/NCNTs@S cathode demonstrates exceptional electrochemical performance across multiple metrics. Galvanostatic charge/discharge tests at 0.1 C show two distinct discharge plateaus corresponding to sulfur reduction to soluble LiPS and their further conversion to Li₂S₂/Li₂S. The polarization voltage gap (E) is minimized to 170 mV, significantly lower than other cathodes (190–285 mV), indicating suppressed overpotential and improved reaction reversibility. Rate capability testing reveals impressive retention: capacities of 1350.0, 1204.7, 1131.9, 1019.9, 923.6, 800.5, and 767.7 mAh g⁻¹ are achieved at current densities from 0.1 to 4 C, respectively, with a 57% capacity retention at 4 C. This highlights the system’s ability to maintain high sulfur utilization even under extreme conditions. Cycling stability is equally compelling: after 300 cycles at 0.1 C, the electrode retains 1089.3 mAh g⁻¹ with 85.6% capacity retention. More impressively, long-term cycling at 2 C shows a capacity retention above 64% after 2000 cycles, accompanied by a Coulombic efficiency exceeding 99.5%. EIS analysis confirms low charge-transfer resistance (16.71 Ω) and minimal increase in internal resistance after cycling, indicating stable electrode-electrolyte interfaces. Post-cycling characterization reveals preserved hierarchical morphology and no structural degradation, proving robustness against repeated volume changes. Visual inspection of separators and lithium anodes shows minimal coloration and dendrite formation, directly linking the superior performance to effective suppression of the LiPS shuttle effect.
Practical Application Potential in Flexible Pouch Cells
Beyond laboratory-scale coin cells, the practical viability of the Ag/VN@Co/NCNTs@S cathode is validated through pouch cell fabrication. A flexible pouch battery was assembled using the same composite, achieving an initial discharge capacity of 1036 mAh g⁻¹ and maintaining 724 mAh g⁻¹ after 60 cycles at 0.5 C. The cell successfully powers a wind-driven car and charges a mobile phone, demonstrating real-world energy delivery capabilities. Even after 60 cycles, it can light a red diode, confirming sustained functionality. This performance remains competitive with commercial lithium-ion batteries, especially considering the high sulfur loading. The system’s ability to maintain good performance at high areal loadings (up to 10.3 mg cm⁻²) is particularly notable, with areal capacities reaching 4.37 mAh cm⁻² after 100 cycles. Such results highlight the scalability and manufacturability of the hierarchical design. The success of the pouch cell underscores the material’s potential for use in portable electronics, electric vehicles, and grid storage. The combination of high energy density, excellent cyclability, and mechanical flexibility positions Ag/VN@Co/NCNTs@S as a leading candidate for next-generation energy storage systems. This work establishes a new paradigm for designing multifunctional nanoreactors where synergy between components and structural hierarchy leads to breakthrough performance in lithium-sulfur batteries.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
