A mini-review on the development of Si-based thin film anodes for Li-ion batteries

This review provides a summary of the progress in research on various Si-based thin films as anode materials for lithium-ion batteries. The lithiation mechanism models, different types of materials from pure monolithic Si thin film to Si-based three-dimensional structured composite thin films, the effect of liquid and solid-state electrolytes on the performance of Si were considered and various available preparation techniques were discussed. A table summarizing important information on such systems including the thin film features, preparation methods and conditions, electrochemical test conditions and obtained results in order to elucidate the approaches used to prepare a stable thin film anode with high capacity and long cycle life is provided. We believe that this review will help the researchers to find some answers and induce some new ideas

WNT-conditioned media differentially affect the proliferation and differentiation of cord blood-derived CD133+ cells in vitro

Cord blood-derived CD133+ cells have a degree of non-hematopoietic potential and express transcripts of pluripotency markers including Oct-4, Sox-2, Rex-1, and leukemia inhibitory factor (LIF) receptor, as well as markers of progenitor cells, such as HoxB4, brachyury, and nestin. Having shown by transcriptome analysis that the mouse embryonic fibroblast (MEF) cells routinely used to maintain pluripotent embryonic stem cells express transcripts of the WNT/BMP families of signaling factors, we have assessed the effects on proliferation and differentiation of CD133+ cells of medium conditioned (CM) by MEF, by NIH3T3, and by NIH3T3 cells stably expressing WNT1, WNT3a, WNT4, WNT5a, and WNT11. Cultivation of CD133+ cells in MEF-CM led to a significant increase in cell number after 7 days of culture, while WNT-1, WNT3a-, and WNT11-CM increased the cell number significantly by 14 days of culture. During this period, WNT3a-CM increased the proportion of nestin-expressing cells and increased the ratio of blast-like cells to macrophages, suggesting that these signaling molecules contribute to the maintenance of an undifferentiated, blast-like phenotype. The number of cells expressing the endothelial-related marker CD31+ was significantly increased following culture in WNT5a- and WNT11-CM, whereas the number of cells positive for von Willebrand (vW) factor was maintained during 14 days of culture only in the presence of WNT4-CM. In addition, WNT5a-CM led to increased β-catenin mRNA levels and the presence of β-catenin protein in the cytoplasm and nucleus, consistent with the activation of the WNT signaling pathway. We conclude that in vitro conditioning of CD133+ cells by media containing specific WNT signaling factors influences the non-hematopoietic potential of CD133+ cells and dynamically alters the expression of the neural stem/progenitor cell marker nestin and the endothelial-related cell surface markers CD31 and vW factor. © 2006, International Society of Differentiation.link_to_subscribed_fulltex

A two layer electrode structure for improved Li Ion diffusion and volumetric capacity in Li Ion batteries

Nanomaterials with different morphologies were placed in discrete layers through the thickness of a negative electrode for a Li ion battery to exploit effectively the intrinsic energy storage capabilities of each nanomaterial morphology and to improve the overall dynamics of Li ion diffusion. The two layer electrode showed a combination of high volumetric capacity and rate capability that surpassed the performance of conventional randomly blended electrodes comprising the same nanomaterials. Local Li ion concentrations were measured through the electrode thickness and clearly showed the benefits of the layered structure over the alternatives. The two layer electrode was fabricated by a flexible and scalable suspension atomization and spray deposition technique with generic potential for improved layered electrodes in a wide range of applications