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- Hernández, Guiomar, et al.
(författare)
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Polyimide-polyether bindersediminishing the carbon content in lithium-sulfur batteries
- 2017
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Ingår i: Materials Today Energy. - : Elsevier BV. - 2468-6069. ; 6, s. 264-270
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Tidskriftsartikel (refereegranskat)abstract
- Lithium-sulfur batteries are on the run to become the next generation energy storage technology. First of all due to its high theoretical energy density but also for its sustainability and low cost. However, there are still several challenges to take into account such as reducing the shuttle effect, decreasing the amount of conductive carbon to increase the energy density or enhancing the sulfur utilization. Herein, redox-active binders based on polyimide-polyether copolymers have been proposed as a solution to those drawbacks. These multiblock copolymers combine the ability of poly (ethylene oxide) to act as polysulfide trap and the properties of the imide groups to redox mediate the charge-discharge of sulfur. Thus, poly (ethylene oxide) block helps with the shuttle effect and mass transport in the electrode whereas the polyimide part enhances the charge transfer promoting the sulfur utilization. Sulfur cathodes containing pyromellitic, naphthalene or perylene polyimide-polyether binders featured improved cell performance in comparison with pure PEO binder. Among them, the electrode with naphthalene polyimide-PEO binder showed the best results with an initial capacity of 1300 mA h g(-1) at C/5, low polarization and 70% capacity retention after 30 cycles. Reducing the amount of carbon black in the cathode to 5 wt%, the cell with the redox-active binder was able to deliver 500 mA h g(-1) at C/5 with 78% capacity retention after 20 cycles. Our results demonstrate the possibility to reduce the amount of carbon by introducing polyimide-polyether copolymers as redox-active binders, increasing the sulfur utilization, redox kinetics and stability of the cell. (C) 2017 Elsevier Ltd. All rights reserved.
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| 2. |
- Yang, Xianzhong, et al.
(författare)
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Plasmon-exciton coupling of monolayer MoS2-Ag nanoparticles hybrids for surface catalytic reaction
- 2017
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Ingår i: Materials Today Energy. - : Elsevier BV. - 2468-6069. ; 5, s. 72-78
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Tidskriftsartikel (refereegranskat)abstract
- The optical properties of monolayer molybdenum disulfide (MoS2)/Ag nanoparticle (NP) hybrids and their application to surface catalytic reactions were studied by transmission, photoluminescence (PL) and Raman spectroscopies. The local surface plasmon resonance (LSPR) of Ag nanoparticles was tuned to better match the exciton energy of monolayer MoS2. The PL of the hybrids was enhanced by more than 50 times when the local surface plasmon resonance (LSPR) peak was tuned systematically from 438 nm to 532 nm, indicating a stronger coupling and higher energy transfer rate between the plasmon of the Ag NPs and the excitons of the MoS2. Additionally, photocatalytic reactions of 4-nitrobenzenethiol (4NBT) were performed on the MoS2, the Ag nanoparticles, and the hybrid MoS2 with Ag nanoparticles. On the MoS2 substrate alone, there is no photocatalytic reaction. With a low laser intensity, the probability of a chemical reaction occurring for molecules directly adsorbed onto the Ag NPs is much lower than the probability of a reaction involving those molecules adsorbed onto the MoS2/Ag substrate. At a higher power, although the electric field was reduced by approximately 30% by the MoS2 layer, there is better efficiency for the plasmon-exciton co-driven surface catalytic reactions on the MoS2/Ag substrate compared to the Ag substrate alone. Our findings illustrate the potential to control hot carriers for better surface catalytic reactions by tuning the exciton-plasmon coupling between the 2D transition metal dichalcogenides (TMDCs) and Ag NPs.
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