Confined replacement synthesis of SnSe nanoplates in N-doped hollow carbon nanocages for high-performance sodium–ion batteries

Abstract

Transition metal selenides are regarded as promising alternatives for Sodium-ion batteries (SIBs) owing to the high theoretical capacity based on conversion reaction. However, the poor electrical conductivity, sluggish reaction kinetics...

ZnSe/SnSe Heterostructure Incorporated with Selenium/Nitrogen Co‐Doped Carbon Nanofiber Skeleton for Sodium‐Ion Batteries

“…Similar to the discharge/charge curves at current density of 0.1 A g −1 , the profiles at different current rates of ZnSe/SnSe@Se,N-CNFs also exhibit no plateaus and become more smooth upon rate increasing (Figure 3e), which indicates that the electrochemical process possibly controlled by the pseudocapacitive behavior (will discuss in the later part). Besides, Figure 3f summarizes the rate performances of reported SnSe-based anodes in terms of Na + ion storage, ZnSe/SnSe@Se,N-CNF composite has an obvious advantage on reversible capacities over the SnSe nanoplates encapsulated into N-doped hollow carbon nanocages (SnSe@N-HCNs), [23] SnSe 2 /nitrogen-doped porous carbon-fiber (SnSe 2 /NPC) flexible film, [24] tin-based chalcogenide encapsulated with 3D Ndoped porous graphene (SnSe 0.5 S 0.5 @NG), [25] SnSe spheres encapsulated in polydopamine (PDA)-derived N, Se dual-doped carbon networks (SnSe@NSC), [26] SnSe nanoparticles co-supported by "inner" sandwich-like r-GO and "outer" nitrogen-doped carbon (SnSe/NC@r-GO), [27] SnSe 2 flakes generated in the doublewalled hollow carbon spheres with N and Se atoms doped (SnSe 2 @N, Se-DWHCSs), [28] porous carbon shell wrapped heterogeneous SnSe/ZnSe composite (SnSe/ZnSe@C), [29] SnSe on nitrogen-doped carbon (SnSe/NC), [17a] and ultrathin layered SnSe nanoplates (SnSe NPs). [30] In addition, the long-term cycling stabilities of ZnSe/SnSe@Se,N-CNFs as well as the bare ZnSe/SnSe, ZnSe, and SnSe powders as comparison are depicted in the Figure 3g.…”

Structural Engineering of SnSe Encapsulated in Nitrogen-Doped Carbon Nanotubes for High-Performance Lithium-Ion Battery Anodes

“…The peaks of Se 3d, Li 1s, N 1s, and C 1s spectra nearly unchange at the fully discharged/charged states in the first cycle (Figure b–d). Moreover, the existence of Sn–C bonding in SnSe@NCNT can be observed during the discharge–charge process (Figure d), implying that the Sn–C bonding plays a vital role in the improvement of conversion reaction. − ,, Meanwhile, Li 2 CO x species that are the main component of SEI film appear after discharging and charging …”

“…Such enhanced specific surface area and pore volume can be attributed to the incorporation of PDA-derived carbon tube and the construction of the hierarchically hollow structure, which increase the electrode−electrolyte contact area, facilitate the penetration of electrolytes, and shorten the diffusion distance for Li + , thereby improving the electrochemical performance. 48,49 The elemental composition and chemical state of SnSe@ NCNT were identified by using XPS spectroscopy. The full spectrum is shown in Figure 3e, indicating the existence of Sn, Se, N, and C elements in the SnSe@NCNT nanocomposite.…”

“…Moreover, the existence of Sn−C bonding in SnSe@NCNT can be observed during the discharge−charge process (Figure 7d), implying that the Sn−C bonding plays a vital role in the improvement of conversion reaction. [33][34][35]43,49 Meanwhile, Li 2 CO x species that are the main component of SEI film appear after discharging and charging. 35 Based on the above results, the exceptional electrochemical performance of the SnSe@NCNT nanocomposite with superior specific capacity, excellent rate performance, and outstanding long cycle stability can be speculated as schematically depicted in Figure 8.…”

“…By comparison, pure SnSe possesses a much smaller specific surface area (23.70 m 2 g –1 ) and pore volume (0.042 cm 3 g –1 ). Such enhanced specific surface area and pore volume can be attributed to the incorporation of PDA-derived carbon tube and the construction of the hierarchically hollow structure, which increase the electrode–electrolyte contact area, facilitate the penetration of electrolytes, and shorten the diffusion distance for Li + , thereby improving the electrochemical performance. , …”