Endowed with high theoretical energy density, low cost, and environmental friendliness, lithium‐sulfur batteries have a promising future in energy storage. The volume expansion of the sulfur cathode, shuttle effects, and the insulating nature of polysulfide result in poor cycling stability and limit practical applications of lithium‐sulfur batteries. In this work, these matters are relieved by physically and chemically restricting sulfur species in highly fluorinated sulfur‐rich multiple covalent triazine frameworks synthesized through nucleophilic aromatic substitution reaction chemistry. It exhibits a specific capacity of 681 mAh g−1 and capacity retention of 62.6 % after 400 cycles, indicating a 0.09 % degradation per cycle. The superiority in cycle performance is attributed to the homogeneous distribution of sulfur, covalent bonding of sulfur, and affinity for polysulfide of triazine rings.
A series of nitrogen-rich porous polyaminal networks (PANs) with five different linkages were prepared through a facile route from cost-effective starting materials. Each structural unit bears a different number of phenyl and pyrrolyl rings, which are found to be useful for iodine uptake through a physical adsorption mechanism. The PAN3 bearing the 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BDP) units, which could adsorb iodine by both physical and chemical interaction, achieves an efficient iodine capacity up to 2.81 g/g. Significantly, these new nitrogen-rich PANs might be useful for capture of other volatile compounds.
Figure 3. a) Schematic diagram of the controlled synthesis of PS@ZIF-8a nd hollow ZIF-8 microspheres. Reproducedw ith permission. [24] Copyright 2012, Royal Society of Chemistry.b )Schematic diagram of the synthesis of hollow ZIF-67 microtubes by using PAN as template. Reproducedw ith permission. [31]
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