To date, most of the research on electrodes for lithium sulfur batteries has been focused on the nanostructured sulfur cathodes and achieves significant success. However, from the viewpoint of manufacturers, the nanos...To date, most of the research on electrodes for lithium sulfur batteries has been focused on the nanostructured sulfur cathodes and achieves significant success. However, from the viewpoint of manufacturers, the nanostructured sulfur cathodes are not so promising, because of the low volumetric energy density and high cost. In this work, we obtained the low-cost, scalable, eco-friendly mass production of edge-functionalized acetylene black-sulfur(FAB-S) composites by high-energy ball-milling technique for lithium sulfur batteries. The as-prepared FAB-S composite can deliver a high initial discharge capacity of 1304 mAh/g and still remain a reversible capacity of 814 mAh/g after 200 cycles at a charge-discharge rate of 0.2 C in the voltage range of 1.7–2.7 V. The observed excellent electrochemical properties demonstrate that the cathodes obtained by the facile high-energy ball-milling method as the cathode for rechargeable Li-S batteries are of great potential because it used the sole conductive additive acetylene black(AB).Such improved properties could be attributed to the partially exfoliation of AB, which not only keeps the AB’s inherent advantage, but also increases the specific surface area and forms chemical bonds between carbon and sulfur, resulting in the accumulation of the polysulfides intermediate through both the physical and chemical routes.展开更多
A thickness-insensitive cathode interlayer （CIL） is necessary for large-area polymer solar cells （PSCs）, in which thickness variation is unavoidable. These C1L materials are typically based on n-type conjugated po...A thickness-insensitive cathode interlayer （CIL） is necessary for large-area polymer solar cells （PSCs）, in which thickness variation is unavoidable. These C1L materials are typically based on n-type conjugated polymer/molecule backbones, which show strong light absorption in the visible/near-infrared （NIR） region. This interferes with the sunlight absorption by the active layer and deteriorates device efficiency. In this study, we developed graphene quantum dots functionalized with ammonium iodide （GQD-NI） at the edge as a thickness-insensitive CIL with high optical transparency. The peripheral ammonium iodide groups of GQD-NI formed the desired interfacial dipole with the cathode to decrease the work function. The graphene basal planes of GQD-NI with a lateral size of ca. 3 nm demonstrated a good conductivity of 3.56 ×10-6 S.cm-1 and high transparency in the visible/NIR region （λmax abs = 228 nm）. Moreover, GQD-NI was readily soluble in polar organic solvents, e.g., methanol, which enabled multilayer device fabrication with orthogonal solvent processing. As a result, the PSC device with GQD-NI as the CIL exhibited a power conversion efficiency （PCE） of 7.49%, which was much higher than that of the device without the CIL （PCE = 5.38%） or with calcium as the CIL （PCE = 6.72%）. Moreover, the PSC device performance of GQD-NI was insensitive to the GQD-NI layer thickness in the range of 2-22 nm. These results indicate that GQD-NI is a very promising material for application as a CIL in large-area printed PSCs.展开更多
Lithium–sulfur batteries have great potential for high energy applications due to their high capacities,low cost and eco-friendliness. However, the particularly rapid capacity decay owing to the dissolution and diffu...Lithium–sulfur batteries have great potential for high energy applications due to their high capacities,low cost and eco-friendliness. However, the particularly rapid capacity decay owing to the dissolution and diffusion of polysulfide intermediate into the electrolyte still hamper their practical applications.And the reported preparation procedures to sulfur based cathode materials are often complex, and hence are rather difficult to produce at large scale. Here, we report a simple mechano-chemical sulfurization methodology in vacuum environment applying ball-milling method combined both the chemical and physical interaction for the one-pot synthesis of edge-sulfurized grapheme nanoplatelets with 3D porous foam structure as cathode materials. The optimal sample of 70%S–Gn Ps-48 h(ball-milled 48 h) obtains 13.2 wt% sulfur that chemically bonded onto the edge of Gn Ps. And the assembled batteries exhibit high initial discharge capacities of 1089 mAh/g at 0.1 C and 950 mAh/g at 0.5 C, and retain a stable discharge capacity of 776 mAh/g after 250 cycles at 0.5 C with a high Coulombic efficiency of over 98%. The excellent performance is mainly attributed to the mechano-chemical interaction between sulfur and grapheme nanoplatelets. This definitely triggers the currently extensive research in lithium–sulfur battery area.展开更多
Covalent modification of graphene oxide(GO)with functional chromophores plays an important role in constructing various kinds of advanced optoelectronic materials for applications in molecular diagnosis,light-harvesti...Covalent modification of graphene oxide(GO)with functional chromophores plays an important role in constructing various kinds of advanced optoelectronic materials for applications in molecular diagnosis,light-harvesting,photodynamic therapy,and optical limiting.Herein,a new approach to functionalizing GO with meso-substituted formylporphyrins at GO’s edge sites via imidazole condensation is developed,which affords a novel GO-imi-Por nanohybrid covalently-linked by imidazole rings between two components.The structure of the GO-imi-Por nanohybrid was thoroughly characterized by scanning electron microscopy(SEM),attenuated total reflectance-Fourier transform infrared(ATR-FTIR),Raman,and X-ray photoelectron spectroscopy(XPS).The red-shifted steady-state absorption,95%quenched fluorescence,and largely enhanced nonlinear optical(NLO)properties through Z-scan studies at lower input energies demonstrate that this GO-imi-Por nanohybrid exhibits a more effective photoinduced energy/electron transfer between the intrahybrid two components and can be flexibly applied as an optical limiter candidate.This covalent edge-functionalization approach provides a new paradigm for constructing various edge-expanding GO nanohybrids with an efficient energy/electron transfer process and improved nonlinear optical effects,which would draw inspiration for engineering more adaptable optoelectronic devices.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.51671074,51602079,51572060,and 51502062)the Fundamental Research Funds for the Central Universities(No.HIT.BRETIII.201224 and 201312)+1 种基金Program for Innovation Research of Science in Harbin Institute of Technology(PIRS of HIT-No.201506)support from the Excellent Youth Foundation of Heilongjiang Scientific Committee(No.JC2015010)
文摘To date, most of the research on electrodes for lithium sulfur batteries has been focused on the nanostructured sulfur cathodes and achieves significant success. However, from the viewpoint of manufacturers, the nanostructured sulfur cathodes are not so promising, because of the low volumetric energy density and high cost. In this work, we obtained the low-cost, scalable, eco-friendly mass production of edge-functionalized acetylene black-sulfur(FAB-S) composites by high-energy ball-milling technique for lithium sulfur batteries. The as-prepared FAB-S composite can deliver a high initial discharge capacity of 1304 mAh/g and still remain a reversible capacity of 814 mAh/g after 200 cycles at a charge-discharge rate of 0.2 C in the voltage range of 1.7–2.7 V. The observed excellent electrochemical properties demonstrate that the cathodes obtained by the facile high-energy ball-milling method as the cathode for rechargeable Li-S batteries are of great potential because it used the sole conductive additive acetylene black(AB).Such improved properties could be attributed to the partially exfoliation of AB, which not only keeps the AB’s inherent advantage, but also increases the specific surface area and forms chemical bonds between carbon and sulfur, resulting in the accumulation of the polysulfides intermediate through both the physical and chemical routes.
文摘A thickness-insensitive cathode interlayer （CIL） is necessary for large-area polymer solar cells （PSCs）, in which thickness variation is unavoidable. These C1L materials are typically based on n-type conjugated polymer/molecule backbones, which show strong light absorption in the visible/near-infrared （NIR） region. This interferes with the sunlight absorption by the active layer and deteriorates device efficiency. In this study, we developed graphene quantum dots functionalized with ammonium iodide （GQD-NI） at the edge as a thickness-insensitive CIL with high optical transparency. The peripheral ammonium iodide groups of GQD-NI formed the desired interfacial dipole with the cathode to decrease the work function. The graphene basal planes of GQD-NI with a lateral size of ca. 3 nm demonstrated a good conductivity of 3.56 ×10-6 S.cm-1 and high transparency in the visible/NIR region （λmax abs = 228 nm）. Moreover, GQD-NI was readily soluble in polar organic solvents, e.g., methanol, which enabled multilayer device fabrication with orthogonal solvent processing. As a result, the PSC device with GQD-NI as the CIL exhibited a power conversion efficiency （PCE） of 7.49%, which was much higher than that of the device without the CIL （PCE = 5.38%） or with calcium as the CIL （PCE = 6.72%）. Moreover, the PSC device performance of GQD-NI was insensitive to the GQD-NI layer thickness in the range of 2-22 nm. These results indicate that GQD-NI is a very promising material for application as a CIL in large-area printed PSCs.
基金the Link Project of the National Natural Science Foundation of China and Guangdong Province(Grant no.U1301244)the National Natural Science Foundation of China(Grant nos.51573215,21506260)+2 种基金Guangdong Province Science&Technology Foundation(2011B050300008)Guangdong Natural Science Foundation(Grant nos.2014A030313159,2016A030313354)Guangzhou Scientific and Technological Planning Project(2014J4500002,201607010042)for financial support of this work
文摘Lithium–sulfur batteries have great potential for high energy applications due to their high capacities,low cost and eco-friendliness. However, the particularly rapid capacity decay owing to the dissolution and diffusion of polysulfide intermediate into the electrolyte still hamper their practical applications.And the reported preparation procedures to sulfur based cathode materials are often complex, and hence are rather difficult to produce at large scale. Here, we report a simple mechano-chemical sulfurization methodology in vacuum environment applying ball-milling method combined both the chemical and physical interaction for the one-pot synthesis of edge-sulfurized grapheme nanoplatelets with 3D porous foam structure as cathode materials. The optimal sample of 70%S–Gn Ps-48 h(ball-milled 48 h) obtains 13.2 wt% sulfur that chemically bonded onto the edge of Gn Ps. And the assembled batteries exhibit high initial discharge capacities of 1089 mAh/g at 0.1 C and 950 mAh/g at 0.5 C, and retain a stable discharge capacity of 776 mAh/g after 250 cycles at 0.5 C with a high Coulombic efficiency of over 98%. The excellent performance is mainly attributed to the mechano-chemical interaction between sulfur and grapheme nanoplatelets. This definitely triggers the currently extensive research in lithium–sulfur battery area.
文摘Covalent modification of graphene oxide(GO)with functional chromophores plays an important role in constructing various kinds of advanced optoelectronic materials for applications in molecular diagnosis,light-harvesting,photodynamic therapy,and optical limiting.Herein,a new approach to functionalizing GO with meso-substituted formylporphyrins at GO’s edge sites via imidazole condensation is developed,which affords a novel GO-imi-Por nanohybrid covalently-linked by imidazole rings between two components.The structure of the GO-imi-Por nanohybrid was thoroughly characterized by scanning electron microscopy(SEM),attenuated total reflectance-Fourier transform infrared(ATR-FTIR),Raman,and X-ray photoelectron spectroscopy(XPS).The red-shifted steady-state absorption,95%quenched fluorescence,and largely enhanced nonlinear optical(NLO)properties through Z-scan studies at lower input energies demonstrate that this GO-imi-Por nanohybrid exhibits a more effective photoinduced energy/electron transfer between the intrahybrid two components and can be flexibly applied as an optical limiter candidate.This covalent edge-functionalization approach provides a new paradigm for constructing various edge-expanding GO nanohybrids with an efficient energy/electron transfer process and improved nonlinear optical effects,which would draw inspiration for engineering more adaptable optoelectronic devices.
