PDF Publication Title:
Text from PDF Page: 060
As a supporting information, BET measurements were done on three samples (Table 2-1). Chapter 2: S8 electrode on Aluminum S/SuperP® Sample (90/10 wt%) S/SuperP®/PVdF (80/10/10 wt%) (*) 5.5 S/SuperP®/CMC/NBR (80/10/6/4 wt%) (*) 3.0 BET surface area (m2 g-1) 5.7 Table 2-1. BET data measured on S/SuperP® mixture and after binder (CMC/NBR or PVdF) incorporation, on TRISTAR II 3020 equipment. BET tests were performed at RT (to avoid sulfur sublimation at elevated temperatures) and under N2 gas. (*) BET tests of complete electrodes were done on the powders scratched from the Al collector, to avoid having the contribution of Al foil mass during the measurement. As the sulfur particles are in the micro scale (-325 mesh, i.e. an average particle size of ~ 44 μm, which corresponds – by assuming a spherical particles – a surface area of 0.00659 m2 g-1), the surface area is mainly associated to SuperP® carbon’s one (60 m2 g-1). The surface area of S/SuperP® was found to be 5.7 m2 g-1, which is rather an expected value, since the fraction of SuperP® in the mixture was 10 wt% (10 % x 60 m2 g-1 = 6.0 m2 g-1). Further addition of PVdF resulted in only slight decrease of the surface area (5.5 m2 g-1) as compared with the CMC- based electrode, where the surface got decreased almost twice (3.0 m2 g-1). Such behavior may indicate that CMC/NBR disperses and covers better the clusters of carbon particles, which results in lower BET value. On the contrary, PVdF may not provide an efficient coverage of carbon, while manual mixing of the ink may not allow for good dispersion of the different electrode’s components, i.e. PVdF and carbon particles. Indeed, this hypothesis is coherent with previous work of He et al.111, who reported on better dispersion of S/C particles in the electrode slurry while using CMC/SBR binder. Cycling performances of PVdF-based electrodes were demonstrated previously on Figure 2-7, where quite drastic capacity fade was observed, followed by a stable discharge capacity of around 300-400 mAh g-1. Cyclability of CMC-based electrodes was also verified (Figure 2-9). The effect of different active mass loadings was also taken into consideration. For that purpose, a larger quantity of the electrode ink was prepared and coated on Al foil sheets with different blade thicknesses. Such obtained electrodes had increasing coating thicknesses (74 → 86 → 91 → 107 → 117 μm), linearly proportional to the sulfur loadings (2.77 → 3.35 → 4.03 → 4.71 → 5.69 mgSulfur cm-2). Figure 2-9 shows the initial voltage profiles obtained at C/20 and C/5 for the electrodes with different loadings (indicated on the graphs), together with capacity retention over prolonged cycling. It can be seen that at slow rate (C/20), the voltage profile is only slightly affected (slight increase in overpotential with increased loading). At faster rate (C/5), the lower discharge plateau is more affected, with high polarization, that could be expected due to the slow reaction kinetics of solid phase formation and a large increase of the electrolyte viscosity (higher polysulfide concentration in the electrolyte). Very surprisingly, upon prolonged cycling, highly loaded electrodes (~ 5.69 mgSulfur cm-2) give much higher capacities as the lower loaded ones 56PDF Image | Accumulateur Lithium Soufre
PDF Search Title:
Accumulateur Lithium SoufreOriginal File Name Searched:
WALUS_2015_archivage.pdfDIY PDF Search: Google It | Yahoo | Bing
Sulfur Deposition on Carbon Nanofibers using Supercritical CO2 Sulfur Deposition on Carbon Nanofibers using Supercritical CO2. Gamma sulfur also known as mother of pearl sulfur and nacreous sulfur... More Info
CO2 Organic Rankine Cycle Experimenter Platform The supercritical CO2 phase change system is both a heat pump and organic rankine cycle which can be used for those purposes and as a supercritical extractor for advanced subcritical and supercritical extraction technology. Uses include producing nanoparticles, precious metal CO2 extraction, lithium battery recycling, and other applications... More Info
CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com (Standard Web Page)