Abstract
Sodium-ion batteries (SIBs) are promising power sources due to the low cost and abundance of battery-grade sodium resources, while practical SIBs suffer from intrinsically sluggish diffusion kinetics and severe volume changes of electrode materials. Metal-organic framework (MOFs) derived carbonaceous metal compound offer promising applications in electrode materials due to their tailorable composition, nanostructure, chemical and physical properties. Here, we fabricated hierarchical MOF-derived carbonaceous nickel selenides with bi-phase composition for enhanced sodium storage capability. As MOF formation time increases, the pyrolyzed and selenized products gradually transform from a single-phase Ni3Se4 into bi-phase NiSex then single-phase NiSe2, with concomitant morphological evolution from solid spheres into hierarchical urchin-like yolk-shell structures. As SIBs anodes, bi-phase NiSex@C/CNT-10h (10 h of hydrothermal synthesis time) exhibits a high specific capacity of 387.1 mAh/g at 0.1 A/g, long cycling stability of 306.3 mAh/g at a moderately high current density of 1 A/g after 2,000 cycles. Computational simulation further proves the lattice mismatch at the phase boundary facilitates more interstitial space for sodium storage. Our understanding of the phase boundary engineering of transformed MOFs and their morphological evolution is conducive to fabricate novel composites/hybrids for applications in batteries, catalysis, sensors, and environmental remediation.
Highlights
Rechargeable sodium-ion batteries (SIBs) are regarded as potential power sources for large-scale energy storage devices due to the low cost and abundance of sodium resources [1,2,3,4]
The morphological evolution of Ni-BTC metal-organic frameworks (MOFs) with time was first characterized by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM)
X-ray diffraction (XRD) analysis of the above samples demonstrated that the Ni-BTC MOFs gradually transform from amorphous to crystalline materials during the solvothermal reactions (Fig. S1 in the Electronic Supplementary Material (ESM))
Summary
Rechargeable sodium-ion batteries (SIBs) are regarded as potential power sources for large-scale energy storage devices due to the low cost and abundance of sodium resources [1,2,3,4]. The large radius of the Na+ ion (0.98 Å compared with 0.69 Å for Li+) accounts for its intrinsically sluggish diffusion kinetics and severe volume changes, usually leading to unimpressive electrochemical performance [5, 6]. On account of these factors, numerous efforts have been devoted to developing stable electrodes in order to achieve good sodium storage ability. Metal selenides usually exhibit higher electronic conductivity and structural stability, and can present an improved cycle life and high rate performance with appropriate electrolytes operating within selected voltage window [18,19,20]. Dramatic volume variations and severe aggregation still took place during long-term cycling, leading to undesirable cycle performance for the metal selenides
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
