Optimization of Full Cell Formulation Factors Based on Silicon – Graphite Composite Negative Electrode

Battery Science & TechnologyIn the state of the art progress in improving the performance of the Lithium Ion Batteries (LIB) full cell, the formulation engineering has received little attention, compared to new structures and new compositions of the electrochemically active material so far. However, much attention is paid to the formulation engineering in the field of battery industry, because it is critically significant in order to manufacture efficient full cells which can be commercialized. Such efforts are quite restricted to access or publication, because they are the proprietary information of the manufacturing companies. This study is focused on the optimization of full cell formulation factors based on silicon-natural graphite composite negative electrode. The considered factors were composition of active materials, binder, electrolyte and cutoff voltage in a full cell. The effect of different particle sizes of natural graphite within the composite, which is composed of silicon and natural graphite, was investigated, in which the composite with smaller natural graphite showed the superior electrical conductive network. The experiment showed that the silicon based composite electrode keeps higher voltage profile than that of natural graphite, especially during delithiation in the half cell. And, the simulation result, computed out of the experimental result, envisioned that it is better to shift cutoff voltage to the lower voltage during discharge in the full cell consisting of silicon–natural graphite composite electrode in order to use the maximum capacity of each electrode, comparing with that of natural graphite electrode. Additionally, a design method of calculating initial discharge capacity in a full cell was investigated. A statistical analysis method making use of Design of Experiments (DOE) was applied to search for the optimized condition for the weight ratio of binder mixture and the electrolyte kind, which showed that the cycle life of silicon-natural graphite composite electrode with the PAA or CMC binders is superior to that with SBR binder. This experimental result enabled me to argue that those binders, which have mechanically high ‘proportional limit stress’ like PAA and CMC, provide more robust bonds among expansive active materials (Si) which, in turn, can be adhered solidly to current collector substrate, compared with SBR and PVDF which have low ‘proportional limit stress’. Such strong bonds are also formed even between Si and Natural graphite of active materials, which contributed to the preservation of electrical conductivity of a composite negative electrode despite under repeated dimensional changes during cycles.ope

Analysis of Transverse Mixing Using Natural Tracers Continuously Introduced from Tributaries

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchive

Two-Dimensional Dirac Fermions Protected by Space-Time Inversion Symmetry in Black Phosphorus

We report the realization of novel symmetry-protected Dirac fermions in a surface-doped two-dimensional (2D) semiconductor, black phosphorus. The widely tunable band gap of black phosphorus by the surface Stark effect is employed to achieve a surprisingly large band inversion up to ~0.6 eV. High-resolution angle-resolved photoemission spectra directly reveal the pair creation of Dirac points and their moving along the axis of the glide-mirror symmetry. Unlike graphene, the Dirac point of black phosphorus is stable, as protected by spacetime inversion symmetry, even in the presence of spin-orbit coupling. Our results establish black phosphorus in the inverted regime as a simple model system of 2D symmetry-protected (topological) Dirac semimetals, offering an unprecedented opportunity for the discovery of 2D Weyl semimetals

Cardiac Angiosarcoma on the Right Atrium: Two Cases

We detected two cases of right atrial angiosarcoma that had a similar appearance on imaging studies. Although the surgical findings were similar for the two patients, one had a clear resection margin, while the other had tumor cells in the resection margin on frozen biopsy. We suggest that preoperative data on magnetic resonance imaging and computed tomography in patients with angiosarcomas may not predict the exact extent of surgical resection or prognostic outcomes

The impact of sequential versus single anastomoses on flow characteristics and mid-term patency of saphenous vein grafts in coronary bypass grafting

ObjectiveTo assess the influence of bypass grafting technique on the flow characteristics and mid-term patency of saphenous vein coronary bypass grafts.MethodsIn the present study, 309 patients who underwent either sequential (group A, N = 84 grafts) or individual (group B, N = 244 grafts) saphenous vein coronary bypass grafting between February 2002 and September 2007 were investigated. Individual bypassing only was performed in 212 patients, and sequential bypassing only was performed in 78 patients. The remaining 19 patients received both. A total of 436 distal anastomoses were performed with 328 saphenous vein grafts. The intraoperative flow characteristics and the graft patency were assessed with the transit time flow meter and serial multi-detector computed tomography coronary angiograms, respectively.ResultsGroup A showed a higher mean flow compared with group B at 49.4 ± 27.4 mL/min versus 37.1 ± 20.1 mL/min, respectively (P = .001). The mean flow increased linearly as the number of anastomoses increased per graft (P < .001). Graft patency at 3 years was 93.3% ± 3.4% in group A and 86.5% ± 3.1% in group B (P = .048). After adjustment for baseline characteristics, group A showed a tendency for superior mid-term patency than group B (hazard ratio 0.362; 95% confidence interval, 0.129–1.017; P = .0538).ConclusionsSequential bypass grafts were associated with higher mean flows and superior mid-term patency compared with individual grafts. These findings suggest the more favorable results of sequential bypass grafting to be attributed to the enhanced flow hemodynamics