Visualizing Nucleation and Growth Process of Vanadium‐Supramolecular Nanoribbons Self‐Assembled by Rapid Cooling Method towards High‐Capacity Vanadium Nitride Anode Materials

Abstract

Metallo-supramolecular polymers (MSPs), including metalorganic frameworks (MOFs) and other organic-inorganic polymers without periodic porous structure via non-covalentThe vanadium-supramolecules and their derivatives are in high demand because of their huge potential applications in various fields, especially as electrodes for supercapacitors and batteries. However, the complex synthesis process is still a significant challenge. Furthermore, for these self-assembly processes, the early reaction stages, intermediates, and details of reaction kinetics are still unknown. Here, an efficient approach of rapid cooling for largescale fabrication of melamine-ammonium metavanadate (C 3 H 6 N 6 -NH 4 VO 3 ) supramolecular nanoribbons is reported, and the corresponding nucleation and growth process are visualized by using an in situ polarizing microscope. The thermally induced nucleation takes place within tens of seconds, and once the nucleus is formed, C 3 H 6 N 6 and NH 4 VO 3 begin to assemble into nanoribbons under thermal control and grow epitaxial around the already-formed nuclei. The growth process is much slower than the nucleation, until all small molecules are consumed. Rapid heat induction (rapid cooling) and shear force induction (stirring) help to form a uniform and wider 2D sheet rather than fibers or ribbons. After pyrolysis, the vanadium-supramolecules derived vanadium nitride (VN)/carbon nanoribbons present a mesoporous structure, which endows the VN/carbon with high capacitance of 266.3 F g −1 at 0.5 A g −1 . In addition, the relationship between various structures and their properties is systematically investigated.

Sulfur‐containing polymer cathode materials: From energy storage mechanism to energy density

“…In addition, shuttle soluble polysulfides (Li 2 S x , x ≥ 4) in the electrolyte is a critical problem, making the energy density of Li‐S batteries low 8–13 . Therefore, a variety of strategies have been developed to form sulfur composites with porous carbon and other favorable structures to optimize the properties of Li‐S batteries 12,14–19 …”

“…[8][9][10][11][12][13] Therefore, a variety of strategies have been developed to form sulfur composites with porous carbon and other favorable structures to optimize the properties of Li-S batteries. 12,[14][15][16][17][18][19] As is well-known, traditional Li-S batteries 20 have a "solid-liquid-solid reactions" corresponding to two discharging plateaus in its voltage profile as shown in Figure 1. Commonly, at high discharging plateau (~2.4 V) element S reduces to high-order polysulfides (Li 2 S x , x > 4), which will diffuse from the cathode to lithium anode under the driving force of electric field and concentration gradient, leading to active materials losing upon the cycling process.…”

Mesoporous vanadium nitride as anion storage electrode for reverse dual-ion hybrid supercapacitor

“…Owing to the presence of OH − ions, it could lead to the occurrence of an equilibrium reaction at high pH, such as the one shown below on the surface of the nitride (or oxynitride) electrode: where VN x O y ‖OH − represents electrical double layer formed by the hydroxyl ions adsorbed on the oxynitride surface induced by ion-dipole attraction which leads to a substantial increase in the specific capacitance (according to most widely accepted theory). Notably, some recent studies on the reaction mechanism of vanadium nitride have shown other possibilities ( Liu et al., 2021 ; Yang et al., 2022 ).

Figure 4 Electrochemical characterizations of MPs VN electrodes with a three-electrode system (A) CV curve of MPs VN electrodes at 50 mV s −1 in 1 M KOH electrolyte.

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Recent advances in supramolecular self-assembly derived materials for high-performance supercapacitors

“…126 Vanadium supramolecules (V-supramolecular) and their derivatives are in boost demand due to their potential applications in various fields, especially as the electrode for supercapacitors and batteries. 127 However, studies on V-supramolecules are still nucleation and growth of vanadium MSPs remain unresolved. To address these problems, the C 3 H 6 N 6 -NH 4 VO 3 supramolecular (V-supramolecular) nanoribbons (Fig.…”