PDF Publication Title:
Text from PDF Page: 041
600 400 200 0 0.0 1.0 2.0 3.0 X-ray energy / keV C:70% S O: 22% S: 8% O C 2μm Figure 3.6: SEM micrograph of an electrode prepared from an electrode slurry mixed with the ultrasonic tip. Magnification: 5 000×. The large sulfur particle is obviously broken. Inset: EDX spectrum of a selected region next to the broken particle, which contains significant amounts of sulfur. glass vial with the ultrasonic tip for 1 min. at a power of only 40 W. The large particle in Fig. 3.6 is obviously broken and its sulfur content spilled all over the electrode even before it got in contact with the electrolyte. As an immediate conclusion of this find- ing, the ultrasonic tip was no longer used. Instead, the much more gentle magnetic stirrer and ultrasonic bath were favored, at the cost of prolonged mixing times. After a discussion with the supplier of the carbon black material (Timcal, Bodio, Switzerland), the procedure described in section 2.3.5 was established. Indeed, the dispersion and hence the spreading are significantly improved over the previous approach as shown in Fig. 3.5c. This electrode, however, suffers from another issue associated with the higher loading: if a thick electrode is dried is too rapidly (e.g. at elevated tempera- ture) tension builds up in the material which can cause cracks. These cracks in turn are related to irreversible structural degradation [134]. To overcome this issue, the electrodes are cut into coin cell sized pieces immediately once they are dry enough, i.e. no longer sticky, and collected in a sealed vial. This measure slows down drying by lack of convection and the accumulation of the toluene solvent in the vial’s atmo- sphere, thus effectively preventing the formation of cracks, see Fig. 3.5d. In addition, the initial drying can be slowed down by placing the electrode inside a closed petri dish directly after the doctor blading. Despite the increased drying time, however, this did not seem to further improve the quality of the electrodes (data not shown). Another electrode prepared according to the recipe optimized for uniformity, cov- erage, and sulfur loading is presented in Fig. 3.7 at a higher magnification in top- down and cross-section view. While its thickness does vary, it is obvious from the cross-section that the composition of the electrode is uniform. No sedimentation or additional agglomeration is observed. At the bottom of the cross-section image, the aluminum current collector with a thin layer of carbon priming is discernible. Al 41 CountsPDF Image | Lithium-Sulfur Battery: Design, Characterization, and Physically-based Modeling
PDF Search Title:
Lithium-Sulfur Battery: Design, Characterization, and Physically-based ModelingOriginal File Name Searched:
Dissertation_David_N._Fronczek_The_Lithium_Sulfur_Battery.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)