A General Metal‐Organic Framework (MOF)‐Derived Selenidation Strategy for In Situ Carbon‐Encapsulated Metal Selenides as High‐Rate Anodes for Na‐Ion Batteries

Abstract

On account of increasing demand for energy storage devices, sodium‐ion batteries (SIBs) with abundant reserve, low cost, and similar electrochemical properties have the potential to partly replace the commercial lithium‐ion batteries. In this study, a facile metal‐organic framework (MOF)‐derived selenidation strategy to synthesize in situ carbon‐encapsulated selenides as superior anode for SIBs is rationally designed. These selenides with particular micro‐ and nanostructured features deliver ultrastable cycling performance at high charge–discharge rate and demonstrate ultraexcellent rate capability. For example, the uniform peapod‐like Fe7Se8@C nanorods represent a high specific capacity of 218 mAh g−1 after 500 cycles at 3 A g−1 and the porous NiSe@C spheres display a high specific capacity of 160 mAh g−1 after 2000 cycles at 3 A g−1. The current simple MOF‐derived method could be a promising strategy for boosting the development of new functional inorganic materials for energy storage, catalysis, and sensors.

Formation of hierarchical Fe7Se8 nanorod bundles with enhanced sodium storage properties

“…The other reduction peak at 1.10 V, which disappears in the subsequent cycles, represents the formation of the SEI[39] . In the following cathodic scans, four peaks appear at 1.73, 1.32, 0.78, and 0.63 V, in agreement with the occurrence of multi-electron transfer reactions during the conversion of Fe 7 Se 8 to Na 2 Se[42] . Three peaks observed in the anodic process are related to the intermediate phase transformation during the formation of Fe 7 Se 8 .…”

Bi‐Metal (Zn, Mn) Metal–Organic Framework–Derived ZnMnO3 Micro‐Sheets Wrapped Uniformly with Polypyrrole Conductive Network toward High‐Performance Li‐Ion Batteries

“…In general, the value of b = 0.5 indicates diffusion‐dominated battery process, and the case of b = 1 suggests the ideal Faradaic pseudocapacitance behavior . For our case, the slope for the anodic peaks with the b ‐value of 0.85, as derived from Figure b, exihibits the mixed electrochemical Li‐storage process for the PPY@ZMO anode .…”

“…The CV profiles are almost identical to each other when the sweep rate increases from 0.3 to 2.3 mV s −1 , as shown in Figure a. In general, the measured current ( i ) as a function of the scan rate ( v ) is expressed by Equation …”

Ru-Doped Ni3Se4/NiSe/Nitrogen-Doped Carbon Nanotube Heterostructure for Lithium Storage

“…Compared with previously reported Ni-based selenides, such as NiSe/C, NiSe, Ni 3 Se 4 /NiSe 2 @C, NiSe/rGO, NiO/NiSe 2 @C, Ni 3 S 2 /NiSe 2 , NiSe 2 /C/rGO, O/C–NiSe 2 @C, etc (Figure c and Table S1, Supporting Information), Ru–Ni 3 Se 4 /NiSe@NC presents more excellent electrochemical performance at current densities from 100 to 2000 mA g –1 and the higher reversible specific capacity. To evaluate the half-cell performance, the rate performance was measured with the current density ranging from 100 to 5000 mA g –1 (Figure d).…”