Spotlights Cite This: J. Phys. Chem. Lett. 2018, 9, 2720−2720
pubs.acs.org/JPCL
Spotlights: Volume 9, Issue 10
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MECHANICALLY STRONG POLYMER SHEETS FROM ALIGNED ULTRAHIGH-MOLECULAR-WEIGHT POLYETHYLENE NANOCOMPOSITES Body armor has come a long way from heavy chain mail and clanking bronze suits. Lightweight, flexible alternatives made of plastics such as ultrahigh molecular weight polyethylene (UHMWPE) have been protecting law enforcement and members of the military for decades. The possible applications for UHMWPE are an exciting area of study, and research is ongoing to establish a clear understanding of the relationship between the polymer’s structure and properties. Zhang et al. (10.1021/acs.jpclett.8b00790) contribute to the effort with their study, in which they investigated boron nitride (BN) nanosheet-doped UHMWPE composites (BN-UHMWPE) with a high degree of alignment through a thermal−mechanical tension process. They found that the nanocomposites have outstanding mechanical and thermal properties over a broad temperature range. BN-UHMWPE’s compressive Young’s modulus, a measure of elasticity, is significantly higher than that of existing polymers, and it has a high operating temperature owing to the greatly improved thermal conductivity and high crystallinity compared with pristine polymers (which are inherently susceptible to thermal runaway). The findings may be useful in expanding the temperature range of UHMWPE-based materials for many purposes, including hightemperature electronics and personal protection.
polysulfide nanofilter (PSNF) in Li−S batteries. The authors found that the PSNF effectively filters the dissolved polysulfides, aids ion transport, and reduces the cell resistance. The electrochemical performances of the resultant Li−S battery, including capacity, cycle stability, and rate capability, are dramatically improved as compared with conventional conductive coating or interlayers. The authors note that a simple pressure drop test, usually used for air filters, can be used to evaluate the coating quality and predict its contribution to electrochemical performances.
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A RECHARGEABLE HYDROGEN BATTERY The hydrogen fuel cell has been touted as the clean solution to the world’s energy crisis, but the promise of this technology has been thwarted by its drawbacks, from storage challenges to safety issues to polluting byproducts. The fact remains that hydrogen is the cleanest chemical energy carrier with high abundance in the known universe, so efforts to overcome the drawbacks continue. Thus far, hydrogen power has been limited to proton exchange membrane fuel cells, where energy storage and conversion are completely decoupled. Dargily et al. (10.1021/acs.jpclett.8b00858) take a different approach, using the proton-coupled electron transfer in hydrogen storage molecules to construct an electrically rechargeable hydrogen battery. They use electrochemical, spectroscopic, and spectroelectrochemical analysis to show the participation of protons during charge−discharge and extended cycling. Their concept based on a virtually nonpolluting energy carrier molecule adds a compelling piece to the sustainable energy puzzle.
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SELF-ASSEMBLED PROTEIN NANOFILTER FOR TRAPPING POLYSULFIDES AND PROMOTING LI+ TRANSPORT IN LITHIUM−SULFUR BATTERIES Humanity’s voracious appetite for portable electronics continues to feed research into advanced battery options that deliver optimal performance, low cost, and reduced environmental harm. Lithium−sulfur (Li−S) batteries have shown great promise in these areas, with their high theoretical energy density, high specific capacity, low cost, and environmental benignity. However, their practical application has been limited by major challenges, particularly the shuttle effect, which results from the dissolution and migration of the polysulfides during the charge/discharge process. These dissolved species become electrochemical “pollutants” that hinder both electrolyte and electrode performance. The shuttle effect is believed to be one of the main reasons for rapid capacity fading and low columbic efficiency, and Fu et al. focus on this issue in their Letter (10.1021/acs.jpclett.8b00836). The authors, inspired by the model of the air filter, propose the concept of polysulfide nanofilter to address the shuttle effect. By combining bionanotechnology and self-assembly techniques, they fabricated a self-assembled nanofilter by surface coating proteintreated conductive fillers. They found that a natural protein such as gelatin can act as a unique functional material capable not only of creating a three-dimensional self-assembled porous structure, but also of chemically trapping the dissolved polysulfides. Thus, this protein-based porous coating acts as a © 2018 American Chemical Society
Published: May 17, 2018 2720
DOI: 10.1021/acs.jpclett.8b01463 J. Phys. Chem. Lett. 2018, 9, 2720−2720
