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Nano-solid spherical Nb2O5/nitrogen-doped carbon (NC) composite is obtained by the hydrothermal method followed by a calcination procedure. The Nb2O5/NC composite exhibits good rate performance and sustainable cyclic stability (144 mAh g−1 at 1000 mAh g−1 upon 2000 charge–discharge cycles) as an anode material in Na-ion batteries (SIBs). The excellent performance of the Nb2O5/NC composite is attributed to its unique nanosphere structure, in which Nb2O5 nanocrystals embedded in porous NC matrix can restrain agglomeration of Nb2O5 nanocrystals and ensure electrolyte accessibility, and the NC matrix can provide effective active sites and increase ions/electrons transfer. This work offers a new method to fabricate nano-solid spherical Nb2O5/NC composite with good Na+ storage property, which can be extended for synthesizing other metal oxide/NC composite as SIB anode. [ABSTRACT FROM AUTHOR]

[Display omitted] The distinctive pomegranate-like Nb 2 O 5 /Carbon@ N -doped carbon (Nb 2 O 5 /C@NC) composites are fabricated using hydrothermal method integrated with nitrogen doped carbon coating procedure. For the SIBs anode, the Nb 2 O 5 /C@NC composites present superior rate character and sustainable capacity (117 mAh g−1 upon 1000 cycles at 5 A g−1). The in-situ X-ray diffraction (XRD) is utilized to research its sodium storage mechanism. Furthermore, for PIBs, the Nb 2 O 5 /C@NC composites present sustainable capacity (81 mAh g−1 upon 1000 cycles at 1 A g−1). The outstanding performance of Nb 2 O 5 /C@NC composites is ascribed to its unique architecture, in which Nb 2 O 5 nanocrystals embedded in porous carbon can restrain agglomeration of Nb 2 O 5 nanocrystals, enhance electron/ion diffusion kinetics, and ensure electrolyte accessibility, and moreover, NC shell layer can provide effective active sites and further increase ions/electrons transfer. [ABSTRACT FROM AUTHOR]

Graphical abstract CNT@SnO 2 @PPy nanocomposites were designed by combining liquid-phase deposition (LPD) and in-situ chemical-polymerization method for sodium-ion battery anodes. Sandwiched CNT@SnO 2 @PPy electrode exhibits excellent rate capability and high capacity retention with a reversible capacity of 226 mAh g−1 after 100 cycles. Abstract CNT@SnO 2 @PPy nanocomposites were designed by combining liquid-phase deposition (LPD) and in-situ chemical-polymerization method for sodium-ion battery anodes. CNT@SnO 2 @PPy nanocomposites maintain one-dimensional structure of CNT in diameters of about 35–45 nm, moreover, the thickness of PPy coating is about 6–8 nm. Sandwiched CNT@SnO 2 @PPy electrode exhibits excellent rate capability and high capacity retention with a reversible capacity of 226 mAh g−1 after 100 cycles at the current density of 100 mA g−1. The improved electrochemical performance may be assigned to the synergistic effects among CNT, SnO 2 , and PPy. It may enhance electrical conductivity, avoid the pulverization of electrode material, and prevent the aggregation of Sn during the charge/discharge processes. [ABSTRACT FROM AUTHOR]

CoMn2O4 films on nickel foam were successfully synthesized by electrostatic spray deposition method followed by annealing in Ar atmosphere for sodium-ion battery anodes. The CoMn2O4 film exhibits porous architecture with a pore size of around 3-4 µm. The CoMn2O4 electrode as a binder-free anode exhibits superior reversible cycling performance and rate capability. It remains reversible specific capacity of 185 mAh g−1 at 100 mA g−1 after 50th cycle. The stable electrochemical performance could be attributed to the unique CoMn2O4 architecture on Ni foam, which could provide high contact area with electrolyte, pronounced tolerance to volume variation, and enhance the electrical conductivity. [ABSTRACT FROM AUTHOR]

ZnSe–FeSe 2 /reduced graphene oxide (RGO) composites are synthesized through a rational strategy using Fe/Zn-MOF-5 as a template. Compared with the ZnSe/RGO or FeSe 2 /RGO composites, the ZnSe–FeSe 2 /RGO anode electrode exhibits a higher reversible capacity (439 mAh g−1 after 100 cycles at 100 mA g−1) for sodium ion batteries (SIBs). The excellent electrochemical performance of ZnSe–FeSe 2 /RGO composites can be attributed to the synergistic effects of the unique architecture, where ZnSe is responsible for providing a high capacity, FeSe 2 improves the electrochemical stability, and RGO is beneficial for enhancing the charge transfer behavior. Furthermore, the ZnSe–FeSe 2 /RGO anode reveals stable reversible capacity (363 mAh g−1 after 100 cycles at 50 mA g−1) for potassium ion batteries (KIBs). [ABSTRACT FROM AUTHOR]

[Display omitted] • A Sn/3DNG composite was fabricated via a one-pot solvothermal method. • The 3D N-doped graphene can improve the rate and cycling performance. • The Sn-C bonds between Sn and 3DNG can enhance the structural stability. • Sn/3DNG anode shows excellent cyclability in full SIB. Tin (Sn) has been recognized as a viable anode material for sodium-ion batteries due to its non-toxic nature, affordability, and high specific capacity. Nonetheless, Sn experiences substantial volume changes during charge–discharge processes, which results in accelerated capacity degradation. Herein, a novel solvothermal method is developed to synthesize a composite of tin nanoparticles covalently bonded to nitrogen-doped three-dimensional graphene (Sn/3DNG) through stable C-Sn bonds. The design of the Sn/3DNG composite effectively mitigates the volume changes of tin during sodium insertion/extraction process by using the robust framework of 3DNG to confine and support Sn nanoparticles. The presence of C-Sn bonds prevents the tin nanoparticles from clumping together, thereby enhancing the electrode's durability. Owing to these improvements, the Sn/3DNG anode exhibits a cyclic retention of 87.7 % after 800 cycles and maintains a substantial specific capacity of 350 mAh g-1 at 5 A g-1. This advancement underscores the potential of Sn-based nanocomposites in advancing the next generation of rechargeable batteries. [ABSTRACT FROM AUTHOR]

Hollow spheres constructed by ZnS-CoS 2 @N-doped Carbon@N-doped carbon (ZnS-CoS 2 @NC@NC) are successfully synthesized using template method combined with NC coating procedure. For SIBs anode, ZnS-CoS 2 @NC@NC electrode exhibits excellent rate property and sustainable capacity of 164 mAh g−1 at 5 A g−1 after 1000 cycles. The superior sodium storage performance for ZnS-CoS 2 @NC@NC composites is benefited from its distinctive structure, in which the hollow architecture for ZnS/CoS 2 @NC@NC composites can buffer the volume change of ZnS/CoS 2 and enhance electronic/ionic conductivity within charge/discharge processes. Furthermore, the NC shell layer can further alleviate structural degradation of ZnS/CoS 2 @NC@NC hollow spheres, and supply more effective active sites. • ZnS/CoS 2 @NC@NC hollow spheres were synthesized by convenient strategy. • ZnS/CoS 2 @NC@NC hollow spheres exhibit excellent cycling performance for SIBs anode. • ZnS/CoS 2 @NC@NC hollow spheres show good rate capability for SIBs anode. [ABSTRACT FROM AUTHOR]

In this work, the Bi 2 Se 3 /Mo 3 Se 4 composite is obtained through electrochemical activation of Bi 2 Se 3 /MoSe 2 composite, which has been synthesized by an ordinary hydrothermal reaction closely followed by selenization process. The Bi 2 Se 3 /Mo 3 Se 4 composite appears good electrochemical property as the negative electrode material for sodium ion batteries (the stable reversible capacity is 409 (346) mAh g−1 at 100 (1000) mA g−1). The outstanding electrochemical property can be attributed to the unique Bi 2 Se 3 /Mo 3 Se 4 composite architecture, in which Bi 2 Se 3 is responsible for offering a high capacity, and Mo 3 Se 4 is responsible for improving electrochemcial stability. Moreover, the small particle sizes for Bi 2 Se 3 /Mo 3 Se 4 resulting from the amorphous to crystalline transitions during cycling is also the cause of the increased stability of the electrode. The design of the Bi 2 Se 3 /Mo 3 Se 4 composite provides a potential tactics to construct other metal selenides composites for sodium-ion battery anode. • Bi 2 Se 3 /Mo 3 Se 4 composite was synthesized by convenient strategy. • Bi 2 Se 3 /Mo 3 Se 4 composite exhibits excellent cycling performance for SIBs anode. • Bi 2 Se 3 /Mo 3 Se 4 composite shows good rate capability for SIBs anode. [ABSTRACT FROM AUTHOR]

• Microstructures constructed by MoSe 2 /C@NC were synthesized by convenient strategy. • MoSe 2 /C@NC composite exhibits excellent cycling performance for SIBs (KIBs) anode. • MoSe 2 /C@NC composite shows good rate capability for SIBs (KIBs) anode. Molybdenum diselenide (MoSe 2) has been drawing increasingly more attention due to its natural abundance, larger interlayer space (~ 6.5 Å) and higher theoretical capacity (422 mA h/g). Nevertheless, the low capacity and the poor cycling stability greatly hinder their application. Here, microstructures constructed by MoSe 2 /C nanoplates sheathed in N-doped carbon (MoSe 2 /C@NC) were synthesized by co-precipitation approach and subsequent annealing treatment with selenium powder. MoSe 2 /C@NC electrode shows the reversible sodium/potassium ion storage capacity of 362 and 310 mA h/g at 0.1 A/g, respectively. In SIBs, the capacity retains 237 mA h/g after a long-term cycling (500 cycles) at 1 A/g. In addition, it is worth noting that the capacity also retains 212 mA h/g at 1 A/g over 100 cycles in PIBs. The excellent performances for sodium and potassium ions storage are credited to the synergistic effect of unique assembly structure of MoSe 2 /C@NC, which can effectively alleviate volume expansion, and improve the electrical conductivity of MoSe 2. [ABSTRACT FROM AUTHOR]