| Carbon material has lots of advantages such as the diversity of porous structure,high surface activity,strong regulation and control,high specific surface area,perfect conductivity and high chemical stability,etc.It is very important in electrochemistry system and it is always a good material of hydrogen-loading and sulfur-loading.electrochemical hydrogen insertion into carbonaceous materials has been proven as an easy and efficient way to store hydrogen under ambient condition.Ordered mesoporous carbons?OMCs?which have high surface area,chemical inertness,and electrical conductivity have become the focus of carbon-sulfur composites.But some of problems always restrain the application such as hydrogen evolution reaction brings the low coulombic efficiency of intercalation hydrogen and“shuttle effect”leads to the poor cyclic stability,etc.According those problems,the major research content and result of this article are as follow:1.Pt nano-particles are loaded onto the surface of an active carbon material through in-situ electrochemical reduction.Pt nano-particles with size of several hundred nano-meters were homogeneously formed on the surface of porous carbon material.The metallic Pt catalyst was used to enhance the electrochemical hydrogen insertion into porous carbon materials.Cyclic voltammetry and galvanostatic charge-discharge method were used to study the electrical properties.Results indicated that,with about10 wt.%of Pt loaded onto carbon,the kinetics of electrochemical hydrogen insertion into porous carbon material is significant improved.The rate as well as the columbic efficiency of H insertion process for Pt loaded AC is much higher than those for AC without Pt loading.The enhancement resulted from the H underpotential deposition on Pt surface and subsequent H spillover from Pt surface to carbon interlayers.2.We proposed here a one-pot route to prepare resorcinol/formaldehyde?RF?resin-based carbon materials with highly ordered mesostructures in an aqueous media.A mesophase transformation from body-centered cubic to 2-D hexagonal structure can be achieved by simply adding1,3,5-trimethylbenzene to the synthesis.and further KOH activation can enhance the surface area to 1344 and 1857 m2 g-1 without destroying the ordered mesostructure,and using them as a conductive carrier preparing sulfur/carbon composite material.The results showed that all three S/C composite electrods exhibit a superhigh coulombic efficiency of 100%,indicating that the mesoporous carbons as prepared in this work could effectively suppress the dissolution loss of the polysulfide intermediates.Benefiting from the high pore volume,high surface area and half-opened channel structure of RF-2-A,the RF-2-A/S compostie not only posseses high sulfur loading content,but also exhibits high capacity and good cycling performance.RF-2-A/S composite with 70 wt%sulfur content and approximately 2mg cm-2 sulfur loading on electrode,delivers a specific capacity of 577 mAh g-1 after100 cycles at 0.2C between 1.5 V and 2.8 V.3.Pt nano-particles are loaded onto the surface of OMCs?RF-1/RF-2?through hydrogen reduction,the Pt catalyst anchored sites of OMCs?RF-1/RF-2?have a strong catalytic effect on sulfur reduction,and their efficient transformation to long-chain polysulfides in the subsequent redox process,and enhance both cycle life and reaction kinetics of the Li-S battery.RF-1-A-Pt/S composite with 50 wt%and60 wt%sulfur content delivers a 1st specific capacity of 1105 mAh g-1?881 mAh g-1at 0.1C,the capacity retention of RF-2-A-Pt/S composite with 60 wt%and 70 wt%sulfur content still keeps 61.4 and 67.9%... |
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