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Antimony（Sb） has high theoretical specific capacity and moderate reaction potential, but poor cycling stability and rate performance caused by large volume expansion and sluggish reaction kinetics limit its development in alkali‐ion batteries. The construction of carbon/Sb composites can solve this problem, but the traditional single carbon composite and poor Sb/carbon interface have limited promotion. Here, under the guidance of theoretical calculations, a strategy of hierarchical double carbon composite is proposed to enhance the performance of Sb anode, and systematically reveal the lithium/sodium ions (Li+/Na+) storage mechanism of Sb in complex composite system. Sb nanoparticles (Sb NPs) are encapsulated in carbon sphere matrix with strong interfacial chemical bond to form the first level composite material, and then the highly conductive and mechanically strong graphene is used as a three‐dimensional skeleton network to connect the first level composite to form the second level composite material. The hierarchical double carbon/Sb composite exhibits excellent rate (228 mAh g−1 @ 20 A g−1) and long cycling performance (373.7 mAh g−1 @ 2 A g−1 after 2200 cycles, capacity retention of 93.1%). This work may expand structural design and interface regulation of Sb/C composites and providing theoretical guidance for metal anodes development. [ABSTRACT FROM AUTHOR]

Highlights: The chemical process of local oxidation–partial reduction–deep coupling for stibnite reduction of carbon dots (CDs) is revealed by in-situ high-temperature X-ray diffraction. Sb2S3@xCDs anode delivers high initial coulombic efficiency in lithium ion batteries (85.2%) and sodium ion batteries (82.9%), respectively. C–S bond influenced by oxygen-rich carbon matrix can restrain the conversion of sulfur to sulfite, well confirmed by X-ray photoelectron spectroscopy characterization of solid electrolyte interphase layers helped with density functional theory calculations. CDs-induced Sb–O–C bond is proved to effectively regulate the interfacial electronic structure. The application of Sb2S3 with marvelous theoretical capacity for alkali metal-ion batteries is seriously limited by its poor electrical conductivity and low initial coulombic efficiency (ICE). In this work, natural stibnite modified by carbon dots (Sb2S3@xCDs) is elaborately designed with high ICE. Greatly, chemical processes of local oxidation–partial reduction–deep coupling for stibnite reduction of CDs are clearly demonstrated, confirmed with in situ high-temperature X-ray diffraction. More impressively, the ICE for lithium-ion batteries (LIBs) is enhanced to 85%, through the effect of oxygen-rich carbon matrix on C–S bonds which inhibit the conversion of sulfur to sulfite, well supported by X-ray photoelectron spectroscopy characterization of solid electrolyte interphase layers helped with density functional theory calculations. Not than less, it is found that Sb–O–C bonds existed in the interface effectively promote the electronic conductivity and expedite ion transmission by reducing the bandgap and restraining the slip of the dislocation. As a result, the optimal sample delivers a tremendous reversible capacity of 660 mAh g−1 in LIBs at a high current rate of 5 A g−1. This work provides a new methodology for enhancing the electrochemical energy storage performance of metal sulfides, especially for improving the ICE. [ABSTRACT FROM AUTHOR]

Ringent hollow carbons synthesised by CDs through controllable reaction temperatures show great absorbing values and absorbing bands as well as relative compression ratios of radar cross section. Finite element simulation demonstrats that unique structure of ringent hollow carbons can lower normal reflected wave and promote energy attenuation which provides a new direction for the structural design of absorbers. [Display omitted] • A high-yield of carbon quantum dots derived ringent hollow carbon spheres (RHCs) for efficient microwave absorber has been proposed. • Outstanding microwave absorbing performance with optimal reflection loss of −67 dB as well as superior absorbing bandwidth (covering C, X and Ku band) could be achieved. • A relative compression ratio of 56.7 % of of RHCs loaded coating could be achieved due to ringent hollow structure and intrinsic nanosheets attenuation. Carbon nanomaterials have steadily grown into a class of composite absorbers with remarkable properties due to their unique structure, low density, high specific surface area, strong electrical conductivity, and substantial dielectric losses. In this paper, a facile strategy with low-cost, high-efficiency, and scalable strategy for carbon dots-derived ringent hollow carbon (RHC) for superior microwave absorption is proposed. Controllable structures ranging from amorphous carbon to ringent hollow carbon are well performed through simple heat-treated temperature. In addition, an optimal absorption value of −67 dB and a superior absorption band width covering the C, X, and Ku bands, as well as a relative compression ratio of 56.7 percent in the case of perpendicular incidence, have been achieved. Further, finite element simulations have demonstrated that the unique structure of partially ringent hollow carbon is considered as an effective way to lower normal reflected wave and promote energy attenuation. New applications of carbon dots-derived RHC as superior microwave absorbers are opening up, and the scalable strategy may pave a solid foundation for rapid applications. [ABSTRACT FROM AUTHOR]

Designing Sb/carbon composite is an effective strategy to enhance the cycle stability and rate capability of Sb anodes for sodium ion batteries. However, the introduction of carbon often leads to a loss in specific capacity and initial Coulombic efficiency (ICE). In this work, a new perspective is adopted by focusing on improving the "sloping capacity" contribution of carbon (C) in Sb/C composites, rather than solely increasing the platform capacity of Sb as traditionally done. Theoretical predictions indicate that constructing Sb/C composites with high Sb and carbon interfacial areas can provide more Na adsorption sites, thus enhancing the "sloping capacity" of amorphous carbon. Guided by DFT, a rational Sb/C/NSCDs‐2(N) is successfully developed by self‐embedding Sb nanodots into 2D‐amorphous carbon sheets doped with N/S. Sb/C/NSCDs‐2(N) exhibits abundant Sb/carbon interfacial areas and excellent nanoscale effects, demonstrating ideal electrochemical sodium storage performances. Impressively, the Sb/C/NSCDs‐2(N) provides a "sloping capacity" close to 160 mAh g−1. Significantly, owing to the fact that these interfaces and defects are not in direct contact with the electrolyte, the side reaction of electrolyte is effectively inhibited, leading to no decrease of ICE. [ABSTRACT FROM AUTHOR]

Antimony-based materials represent promising anode materials for sodium ion batteries (SIBs) owing to their high theoretical capacity, however, the large volume expansion and low ionic conductivity during the electrochemical process prohibit them from reaching their theoretical expectations. In this work, Sb 2 S 3 @C and Sb 2 Se 3 @C nanodots with uniform diameters of 19.0 nm and 20.7 nm were synthesized by H 2 /C thermal reduction and co-sulfurization (selenization) of sodium stibogluconate. Each Sb 2 S 3 and Sb 2 Se 3 nanodot was coated by an interconnecting carbon network with weak graphitization, which further crosslinked together to form a high conductive framework. When applied as anode for SIBs, they exhibited desired sodium storage properties, especially the excellent cycling stability of Sb 2 Se 3 @C nanodots with a reversible capacity of 316.1 mA h g−1 after 100 cycles at 100 mA g−1 and 269.1 mA h g−1 after 200 cycles at 1 A g−1, which was consistent with the calculated result of theoretical volume changes (264% and 246%) and density functional theory (DFT) calculation for both materials during the Na+ intercalation processes, as expected. [Display omitted] • Sb 2 S 3 (Sb 2 S 3) nanodots/C composites have been successfully fabricated. • The volume changes of two materials during the Na+ insertion/deintercalation process have been calculated and analyzed in details. • The satisfactory sodium storage properties are achieved, which is consistent with the result of theoretical calculation. [ABSTRACT FROM AUTHOR]

Antimony (Sb) is considered a promising anode material for sodium‐ion batteries due to its high specific capacity and moderate working potential. However, the non‐negligible volume variation leads to the rapid decay of capacity, which hinders the practical application of Sb anode materials. Here, an economical and scalable route with high yield is proposed to obtain Sb ultrafine nanocrystals embedded in a porous carbon skeleton. Notably, the synergetic effect of the heterogeneous structure is maximized by inducing the interfacial coupling SbOC and creating buffering space for the volume effect of Sb. The high‐entropy phase interface creates the doping site breaking the periodicity of atoms and alters the electronic structure, also bridging the slip of intergranular defects. Thus, the electronic conductivity and phase interface structural stability are reinforced. The mechanism of accelerating electron migration at the heterogeneous phase interface is visualized through the density functional theory method, and the mass/charge‐transfer kinetics is analyzed via the calculation of surface‐induced capacitive contribution. [ABSTRACT FROM AUTHOR]

Bi-doped carbon dots (Bi-CDs) with rich polar groups and good compatibility were employed as co-deposition electrolyte additives to homogenize Li+ flux for dendrite-free Li deposition. High coulombic efficiency (99.0%) and long-term stability (800 h) with reduced overpotential (∼15 mV) were achieved after introducing Bi-CDs in conventional electrolyte for high-performance Li–S batteries. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) are considered as excellent structural regulator for metal oxides (MOs) due to their abundant functional groups, superior dispersibility, and ultrasmall size (<10 nm). Herein, a new approach is proposed to construct porous pomegranate‐like MOs/CDs composite based on the CDs‐induced in situ growth mechanism of ion adsorption–multipoint surface nucleation–crosslinking agglomeration. The proposed methodology is successfully applied to prepare SnO2/CDs, Cu2O/CDs, and Fe2O3/CDs composites, respectively, demonstrating its universality to metal oxides. Taking SnO2/CDs composite as a case study for anode material in lithium‐ion batteries, it exhibits high lithium storage capacity, excellent cycling stability, and a special feature of capacity increase upon cycling. This study provides a new idea for the design of metal oxides materials tuned by CDs and broadens the application of CDs in the field of material synthesis. [ABSTRACT FROM AUTHOR]