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Polyanionic Na3V2(PO4)3 is considered as a promising cathode material for sodium-ion batteries; however, it is limited by its poor electronic conductivity resulting in inferior rate capability and cycling stability. Herein, the rational design and synthesis of Na3V2(PO4)3 (NVP) particles embedded in various N-doped carbon matrices, that is, nitrogen-doped pyrolytic carbon (N−C), carbon nanotubes (N-CNT), graphene nanosheets (N-rGO), and Ketjen black nanospheres (N-KB), are reported together with the structural investigation and electrochemical performance. It is evidenced that the N-doped carbon coating efficiently improves the rate capability and cyclability with minor polarization of NVP materials as a result of enhanced electronic/ionic conductivities and facilitated charge transfer at the electrode−electrolyte interface. Particularly, the NVP nanograins dispersed in the N-doped carbon nanotube matrix exhibit the best rate and cycling performance. When cycled at rates from 0.1 to 20 C, the discharge capacity decays only slightly from 114 to 100 mAh g−1, offering outstanding high power capacity retention (88 %). Moreover, the material retains excellent capacity (92 %) upon long-term cycling (3000 cycles) at extremely high rate of 50 C. [ABSTRACT FROM AUTHOR]

In this study, the interactions of magnesium (Mg) atom and Mg(001) surface with different metal-atom-doped graphene were investigated using a density functional theory (DFT) method. For the interactions of magnesium with Al-, Mn-, Zn-, and Zr-doped and intrinsic graphene, it was found that the magnesium atoms were physisorbed into the hollow sites of the intrinsic graphene with only the smallest interaction energy (approximately −1.900 eV). However, the magnesium atoms tended to be chemisorbed on the doped graphene, which exhibited larger interaction energies and charge transfers. Additionally, the Zn-doped graphene displayed the largest interaction energy with the Mg atom (approximately −3.833 eV). For the interactions of Mg(001) with Al-, Mn-, Zn-, and Zr-doped and intrinsic graphene (intrinsic and doped graphene/Mg interface), doped atoms interacted with a Mg layer to make graphene wrinkle, resulting in a higher specific surface area and better stability. Mg–C chemical bonds were formed at the Al-, Zn-, and Zr-doped interface, and Mg–Mn chemical bonds were formed at the Mn-doped interface. This study provided the fundamental research for future research into doped atoms on graphene reinforced magnesium matrix composites. [ABSTRACT FROM AUTHOR]

Rechargeable aqueous zinc batteries (AZBs) have been regarded as promising large-scale energy storage technologies, due to their low cost and high safety. However, the dendrite growth and side reactions on the Zn metal anode hinder their practical application. Herein, the cotton textiles-based separators with easily-fabricated and cost-effective features are demonstrated for AZBs. By complexing inorganic fluoperovskite NaZnF 3 and organic Nafion layers, the as-fabricated separator (CT@NZF@N) can regulate the zinc plating/stripping behavior, which will reduce the zinc nucleation overpotential and lower the charge transfer resistance, thus achieving a highly reversible Zn plating/stripping process with corrosion-free and dendrite-free behavior. Consequently, the zinc symmetric cell with CT@NZF@N separator exhibits prolonged cycle life up to 300 h (0.5 mA cm−2, 0.5 mAh cm−2) in a mild ZnSO 4 electrolyte. Moreover, the functional separator also enables V 2 O 5 //Zn battery significantly improved rate capability and cyclability. This work provides an appealing strategy for designing reliable, efficient, and cost-effective separators for high-performance AZBs. [Display omitted] • The NaZnF 3 and Nafion-decorated cellulose-based separators were fabricated. • The separators can regulate the zinc deposition behaviour in aqueous electrolyte. • The separators enable the V 2 O 5 //Zn battery improved performance. [ABSTRACT FROM AUTHOR]

• Biphasic Fe 7 S 8 @MnS heterostructure embedded in sulfur-doped carbon matrix was synthesized. • The composites exhibit enhanced lithium storage performance with high rate capability and long cycling stability. • These results can be attributed to the multiphasic components with heterostructures and porous conductive carbon frameworks. Transition metal chalcogenides have been regarded as promising anode candidates for lithium-ion batteries, featured by their high capacity and abundant material choice. However, their practical implementation was hindered by the poor reaction kinetics and rapid capacity fading due to their low electronic conductivity and severe volume variation upon the (de-)lithiation processes. Here, we have successfully fabricated the biphasic Fe 7 S 8 @MnS heterostructure embedded in sulfur-doped carbon matrix by direct sulfidation of Fe/Mn bimetal-organic frameworks. The biphasic heterostructure and the porous carbon frameworks can create abundant phase boundaries and multiple conductive channels for change transfer, thus improving the electronic conductivity and contact area with electrolyte, leading to facilitated charge transfer capability. As a result, the Fe 7 S 8 @MnS/C composites exhibit superior lithium storage performance with a specific capacity of 917 mA h g−1 at 0.1 A g−1 and maintain at 581 mA h g−1 after 500 cycles at 1 A g−1. This work provides an efficient strategy for constructing multiphase nanomaterials towards high performance anodes for Li-ion batteries. [ABSTRACT FROM AUTHOR]

• Biomass-derived carbon is used for conversion-alloying type anodes. • ZnMn 2 O 4 nanoparticles in porous carbon are successfully synthesized. • The composites deliver superior lithium storage performance with high capacity and good cyclability. • The unique structure with ZnMn 2 O 4 nanoparticle and porous carbon integration accounts for the superior performance. Conversion-alloying type anode materials are conceived as very promising candidates to replace graphite for high-energy lithium-ion batteries. Here, we demonstrated a facial approach using biomass-derived carbon to improve the ZnMn 2 O 4 materials as anodes. A composite of ZnMn 2 O 4 nanoparticles/pine needle-derived carbon is synthesized with a high reversible capacity of 1000 mA h g−1 at 0.2 C and superior rate capability of 727 mA h g−1 at 2.0 C without capacity loss for 500 cycles. Pseudocapacitive contribution and highly improved conversion reaction mechanisms are responsible for the capacity improvement. Moreover, the conductive biomass-derived porous carbon can facilitate the charge transfer and buffer the volume expansion upon conversion-alloying reactions of the ZnMn 2 O 4 materials. This work provides a feasible way to fabricate low-cost and high performance materials for lithium-ion batteries towards higher sustainability. [ABSTRACT FROM AUTHOR]