Search Results (4)

A novel porous carbon, derived from polybenzoxazine and subjected to hydrogen peroxide treatment, has been meticulously crafted to serve dual functions as a supercapacitor and a CO₂ capture material. While supercapacitors offer a promising avenue for electrochemical energy storage, their widespread application is hampered by relatively low energy density. Addressing this limitation, our innovative approach introduces a three-dimensional holey carbon ball framework boasting a hierarchical porous structure, thereby elevating its performance as a metal-free supercapacitor electrode. The key to its superior performance lies in the intricate design, featuring a substantial ion-accessible surface area, well-established electron and ion transport pathways, and a remarkable packing density. This unique configuration endows the holey carbon ball framework electrode with an impressive capacitance of 274 F g⁻¹. Notably, the electrode exhibits outstanding rate capability and remarkable longevity, maintaining a capacitance retention of 82% even after undergoing 5000 cycles in an aqueous electrolyte. Beyond its prowess as a supercapacitor, the hydrogen peroxide-treated porous carbon component reveals an additional facet, showcasing an exceptional CO₂ adsorption capacity. At temperatures of 0 and 25 °C, the carbon material displays a CO₂ adsorption capacity of 4.4 and 4.2 mmol/g, respectively, corresponding to equilibrium pressures of 1 bar. This dual functionality renders the porous carbon material a versatile and efficient candidate for addressing the energy storage and environmental challenges of our time. Full article

In this study, we are reporting the impact of the incorporation of ferroelectric nanoparticles (FNPs), such as BaTiO₃ (BTO), BiFeO₃ (BFO), Bi₄NdTi₃Fe_0.7Ni_0.3O₁₅ (BNTFN), and Bi₄NdTi₃Fe_0.5Co_0.5O₁₅ (BNTFC), as well as the mass loading of sulfur to fabricated solvent-free sulfur/holey graphene-carbon black/polyvinylidene fluoride (S/FNPs/CBhG/PVDF) composite electrodes to achieve high areal capacity for lithium-sulfur (Li-S) batteries. The dry-press method was adopted to fabricate composite cathodes. The hG, a conductive and lightweight scaffold derived from graphene, served as a matrix to host sulfur and FNPs for the fabrication of solvent-free composites. Raman spectra confirmed the dominant hG framework for all the composites, with strong D, G, and 2D bands. The surface morphology of the fabricated cathode system showed a homogeneous distribution of FNPs throughout the composites, confirmed by the EDAX spectra. The observed Li⁺ ion diffusion coefficient for the composite cathode started at 2.17 × 10⁻¹⁶ cm²/s (S₂₅(CBhG)₆₅PVDF₁₀) and reached up to the highest value (4.15 × 10⁻¹⁵ cm²/s) for S₂₅BNTFC₅(CBhG)₆₀PVDF₁₀. The best discharge capacity values for the S₂₅(CBhG)₆₅PVDF₁₀ and S₂₅BNTFC₅(CBhG)₆₀PVDF₁₀ composites started at 1123 mAh/g_s and 1509 mAh/g_s and dropped to 612 mAh/g_s and 572 mAh/g_s, respectively, after 100 cycles; similar behavior was exhibited by the other composites that were among the best. These are better values than those previously reported in the literature. The incorporation of ferroelectric nanoparticles in the cathodes of Li-S batteries reduced the rapid formation of polysulfides due to their internal electric fields. The areal capacity for the S₂₅(CBhG)₆₅PVDF₁₀ composites was 4.84 mAh/cm² with a mass loading of 4.31 mg_s/cm², while that for the S₂₅BNTFC₅(CBhG)₆₀PVDF₁₀ composites was 6.74 mAh/cm² with a mass loading of 4.46 mg_s/cm². It was confirmed that effective FNP incorporation within the S cathode improves the cycling response and stability of cathodes, enabling the high performance of Li-S batteries. Full article

Sodium–ion batteries (SIBs) are essential for large–scale energy storage attributed to the high abundance of sodium. Polyanion Na₃V₂(PO₄)₃ (NVP) is a dominant cathode candidate for SIBs because of its high-voltage and sodium superionic conductor (NASICON) framework. However, the electrochemical performance of NVP is hindered by the inherently poor electronic conductivity, especially for extreme fast charging and long-duration cycling. Herein, we develop a facile one-step in-situ polycondensation method to synthesize the three-dimensional (3D) Na₃V₂(PO₄)₃/holey-carbon frameworks (NVP@C) by using melamine as carbon source. In this architecture, NVP crystals intergrown with the 3D holey-carbon frameworks provide rapid transport pathways for ion/electron transmission to increase the ultrahigh rate ability and cycle capability. Consequently, the NVP@C cathode possesses a high reversible capacity of 113.9 mAh g⁻¹ at 100 mA g⁻¹ and delivers an outstanding high–rate capability of 75.3 mAh g⁻¹ at 6000 mA g⁻¹. Moreover, it shows that the NVP@C cathode is able to display a volumetric energy density of 54 Wh L⁻¹ at 6000 mA g⁻¹ (31 Wh L⁻¹ for NVP bulk), as well as excellent cycling performance of 65.4 mAh g⁻¹ after 1000 cycles at 2000 mA g⁻¹. Furthermore, the NVP@C exhibits remarkable reversible capabilities of 81.9 mAh g⁻¹ at a current density of 100 mA g⁻¹ and 60.2 mAh g⁻¹ at 1000 mA g⁻¹ even at a low temperature of −15 °C. The structure of porous carbon frameworks combined with single crystal materials by in-situ polycondensation offers general guidelines for the design of sodium, lithium and potassium energy storage materials. Full article

Given its high-capacity of multielectron (de-)lithiation, SnO₂ is deemed as a competitive anode substance to tackle energy density restrictions of low-theoretical-capacity traditional graphite. However, its pragmatic adhibition seriously encounters poor initial coulombic efficiency from irreversible Li₂O formation and drastic volume change during repeated charge/discharge. Here, an applicable gel pyrolysis methodology establishes a SnO₂/Fe₂O₃ intercalated carbon monolith as superior anode materials for Li ion batteries to effectively surmount problems of SnO₂. Its bulk-like, micron-sized, compact, and non-porous structures with low area surfaces (14.2 m² g⁻¹) obviously increase the tap density without compromising the transport kinetics, distinct from myriad hierarchically holey metal/carbon materials recorded till date. During the long-term Li⁺ insertion/extraction, the carbon matrix not only functions as a stress management framework to alleviate the stress intensification on surface layers, enabling the electrode to retain its morphological/mechanic integrity and yielding a steady solid electrolyte interphase film, but also imparts very robust connection to stop SnO₂ from coarsening/losing electric contact, facilitating fast electrolyte infiltration and ion/electron transfer. Besides, the closely contacted and evenly distributed Fe₂O₃/SnO₂ nanoparticles supply additional charge-transfer driving force, thanks to a built-in electric field. Benefiting from such virtues, the embedment of binary metal oxides in the dense carbons enhances initial Coulombic efficiency up to 67.3%, with an elevated reversible capacity of 726 mAh/g at 0.2 A/g, a high capacity retention of 84% after 100 cycles, a boosted rate capability between 0.2 and 3.2 A g⁻¹, and a stable cycle life of 466 mAh/g over 200 cycles at 1 A g⁻¹. Our scenario based upon this unique binary metal-in-carbon sandwich compact construction to achieve the stress regulation and the so-called synergistic effect between metals or metal oxides and carbons is economically effective and tractable enough to scale up the preparation and can be rifely employed to other oxide anodes for ameliorating their electrochemical properties. Full article