Carbon aerogel anodes

The contribution by Rouzaud et al. teaches to apply a modified version of high resolution Transmission Electron Microscopy (TEM) as an efficient technique of quantitative investigation of the mechanism of irreversible capacity loss in various carbon candidates for application in lithium-ion batteries. The authors introduce the Corridor model , which is interesting and is likely to stimulate active discussion within the lithium-ion battery community. Besides carbon fibers coated with polycarbon (a candidate anode material for lithium-ion technology), authors study carbon aerogels, a known material for supercapacitor application. Besides the capability to form an efficient double electric layer in these aerogels, authors... 

First results indicate a dependence of the surface capacitance of untreated carbon aerogels on their microstructure. Micro- and mesopores exhibit different storage capacitances (6.6 and 19.4 pF/cm in 1 M sulfuric acid, respectively).. An optimized thermal activation procedure of low density aerogels at 950°C in controlled CO2- atmosphere leads to an increase of the specific surface area and capacitance. On the other hand, the increase of the capacitive current after anodic oxidation in sulfuric acid is caused by electroactive surface groups, while the BET-surface area remains almost constant. 

The application of electrochemical investigations is an efficient method to characterize the microstructure of porous electrically conducting materials. Modifications in the chemical constitution of the skeleton which do not change the BET values can be identified by the electrochemically derived surface capacitance, as demonstrated in the case of anodically oxidized carbon aerogels. 

The influence of the mesopore size of carbon aerogels on ORR using Pt-doped carbon aerogels has also been reported by other authors [86]. They found practically no influence of pore texture on Pt dispersion. However, they indicate that the ORR activity increased when the mean mesopore size increased, reaching the best ORR performance for a mesopore size of 18.5 nm. Pt-based catalysts have also been used as anodic catalysts in DMFC systems, since Pt is able to activate the C-H bond cleavage in the temperature range of fuel cell operation (298 to 403 K). Thus, different Pt, Pt-Ni, and Pt-Ru catalysts supported on carbon xerogels have been used as catalysts in DMFC systems [87-90]. 

Finally, the nse of Pt-Rn catalysts snpported on a carbon aerogel as an anode for DMFC has been reported by Dn and co-workers [90]. The total metal loading was fixed to 20 wt%, and the Pt/Rn atomic ratio varied from 3 1 to 1 1. Metal particles were dispersed on the snpport nniformly, with a mean size of 3 nm. These anthors fonnd that with mnch less metal loading on the carbon aerogel, the membrane electrode assemblies had the same power density as that of commercial catalysts. This was attributed to the mesopore texture of the carbon aerogel, which facilitated methanol transportation in the electrode. 

Du H, Li B, Kang F, Fu R, Zeng Y (2007) Carbon aerogel supported Pt-Ru catalysts for using as the anode of direct methanol fuel cells. Carbon 45 429-435... 

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