Search

Vanadium oxides are potential anode materials for sodium-ion batteries, however, their application is limited for their rate capability and cycle life. Herein, hollow spheres of Co-doped V 2 O 3 enveloped in N-doped carbon (Co-V 2 O 3 @NC) are prepared through a hydrothermal step with the following sintering process. The hollow spherical structure supplies short distance and large area for fast ion transfer kinetics, which also provides voids to ease the volume expansion. The strong coupling between Co-V 2 O 3 nanoparticles and carbon layer constitutes a solid structure that enhances the conductivity and keeps electrode integrity. Co-doping introduces plenty of active sites for surface capacitance behavior and accelerates charge transfer. On account of the benefits, Co-V 2 O 3 @NC exhibits excellent Na+ storage properties as anode, including high capacity of 338.5 mAh g−1 at 0.1 A g−1, stable cycling capability of 240 mAh g−1 after 1000 cycles at 1 A g−1, and excellent rate performance. This work describes the importance of constructing specific structured materials for advanced anodes. [Display omitted] • Hollow spheres of Co-doped V 2 O 3 enveloped in N-doped carbon are prepared. • Hollow structure accelerates ion transfer kinetics and buffers volume expansion. • Co-doping provides sites for surface-controlled sodium storage. • Carbon coating improves conductivity and benefits electrode integrity. • High-performance sodium storage performances are acquired. [ABSTRACT FROM AUTHOR]

Heterostructure fabrication is believed to acquire promoted charge transfer and improved surface storage contribution, thus obtaining high-performance anodes for sodium-ion batteries. Herein, the simultaneous phosphatization and selenization of polydopamine functionalized ZIF-67 is adopted to engineer N-doped carbon coated Co(PO 3) 2 /CoSe 2 heterostructure. The hetero-interface with plenty of surface sites is activated with large surface reaction and fast sodium ion transport dynamics. The multiphase synergism and carbon coating layer assure high conductivity and structural stability. The designed sample delivers impressive anode performance, exhibiting a high sodium storage capacity of 333.4 mAh g−1 at 0.1 A g−1 and 192.7 mAh g−1 after 1000 cycles at 2 A g−1. This simple and reasonable method can be utilized to construct other transition metal based heterostructures with multiphase synergism for the application of advanced anodes. [Display omitted] • N-doped carbon coated Co(PO 3) 2 /CoSe 2 heterostructure is prepared. • Heterostrucrue favors surface-controlled pseudocapacitive sodium storage. • N-doped carbon shell enhances conductivity and keeps electrode integrity. • Multiphase synergism benefits electrochemical kinetics and structure stability • Large/fast sodium storage properties with excellent stability are obtained. [ABSTRACT FROM AUTHOR]

• S, N co-doped carbon nanosheets are prepared as SIBs anode. • S, N co-doping endows enlarged interlamellar spacing and defective active sites for improved sodium storage. • S, N co-doping improves Na+ diffusion coefficient. • High capacity of 270 mAh g−1 is obtained at 0.1 A g−1 after 100 cycles. • Capacity of 100 mAh g−1 is achieved at high rate of 1 A g−1 after long-term 1000 cycles. Heteroatom doping into specific nanostructure is believed as the leading solution for developing the advanced carbon materials for sodium ion batteries (SIBs), however, the preparation and understanding of heteroatoms co-doped carbon anodes are still challenging. Herein, the sulfur and nitrogen co-doped (weight content of 15.64% for N and 3.1% for S) carbon nanosheets (SNC) are prepared by treating nitrogen-rich carbon nanosheets with sublimation sulfur. The S, N co-doping is responsible for the enlarged interlamellar spacing of 0.38 nm and abundant defect-introduced active sites. These structure features combined with the advantage of nanosheet are significant for activating sodium ion storage properties, endowing SNC with high Na+ storage capacity of 270 mAh g−1 at 0.1 A g−1 and 100 mAh g−1 at 1 A g−1 after 1000 cycles. More importantly, the kinetic analysis is carried out to illustrate that S, N co-doping can improve the Na+ diffusion coefficient in carbon anode and enhance the ion storage. This work deepens the understanding on the boosting effect of heteroatoms dual-doping for the sodium ion storage of carbon materials, which conduces to development of advanced heteroatom doped carbon anodes for SIBs. [ABSTRACT FROM AUTHOR]