Improvement of Thermal Stability of Li-Ion Batteries by Polymer Coating of LiMn2O4

A new approach has been used to minimize surface degradation of the LiMn2O4 cathode in lithium ion batteries by using surface modification. LiMn2O4 particles used as active material in cathode fabrication were modified by surface adsorption of poly(diallyldimethylammonium chloride) (PDDA). Adsorption and electrochemical performance of the modified cathode material were characterized and compared with that of the untreated LiMn2O4-based cathode. Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray analysis (EDAX) analyses confirmed the formation of a thin polymer film on the surface of LiMn2O4 particles. The modified LiMn2O4–based cathode showed improved stability during charge/discharge cycling in organic electrolyte at room temperature. Further, the measured capacity fading after storage at elevated temperature decreased. Capacity fading measured on cathodes made of PDDA-coated LiMn2O4 powder was smallest for cathodes obtained from powder coated in solutions containing between 30 and 50 mM PDDA. In situ AFM observation of the cathodes at room temperature showed minor changes in surface topography during a potential cycle. Our hypothesis is that the adsorbed polymer layer blocks surface reactions that cause degradation. The present method for surface modified LiMn2O4 (SM-LMO) particles extends the lifetime of the lithium-ion battery by arresting the Mn+ dissolution, thereby increasing the battery stability

Improvement of Thermal Stability of Li-Ion Batteries by Polymer Coating of LiMn2O4

A new approach has been used to minimize surface degradation of the LiMn2O4 cathode in lithium ion batteries by using surface modification. LiMn2O4 particles used as active material in cathode fabrication were modified by surface adsorption of poly(diallyldimethylammonium chloride) (PDDA). Adsorption and electrochemical performance of the modified cathode material were characterized and compared with that of the untreated LiMn2O4-based cathode. Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray analysis (EDAX) analyses confirmed the formation of a thin polymer film on the surface of LiMn2O4 particles. The modified LiMn2O4–based cathode showed improved stability during charge/discharge cycling in organic electrolyte at room temperature. Further, the measured capacity fading after storage at elevated temperature decreased. Capacity fading measured on cathodes made of PDDA-coated LiMn2O4 powder was smallest for cathodes obtained from powder coated in solutions containing between 30 and 50 mM PDDA. In situ AFM observation of the cathodes at room temperature showed minor changes in surface topography during a potential cycle. Our hypothesis is that the adsorbed polymer layer blocks surface reactions that cause degradation. The present method for surface modified LiMn2O4 (SM-LMO) particles extends the lifetime of the lithium-ion battery by arresting the Mn+ dissolution, thereby increasing the battery stability

Uncovering Cortical Modularity by Nanotechnology

Cortical modularity and nanotechnology might look like a strange pair of concepts taken together, but nevertheless they seem very much suited for each other. Indeed, cortical modularity is a fundamental microanatomic feature of the brain while nanotechnology with its nanometric precision provides nanoscale structures, namely nanowires and carbon nanotubes capable of interacting with the brain at the genetic, molecular, and microcircuit level. Research in neuroscience is essentially a combination of many interdisciplinary sciences where nanoscience and nanotechnology plays a pivotal role. In this chapter we examine carbon nanotubes (CNTs) and nanowires (NWs), and their potential to uncover the function of cortical microcircuits, as well as novel applications for diagnosis and treatment of brain diseases. For example, the simultaneous recording from cortical minicolumns with multi-electrode arrays (MEAs) consisting of CNTs or NWs is emerging for developing cognitive prostheses for a broad range of neurological and psychiatric dysfunctions

The Growth of Ga2O3 Nanowires on Silicon for Ultraviolet Photodetector

We investigated the effect of silver catalysts to enhance the growth of Ga2O3 nanowires. The growth of Ga2O3 nanowires on a P+-Si (100) substrate was demonstrated by using a thermal oxidation technique at high temperatures (~1000 °C) in the presence of a thin silver film that serves as a catalyst layer. We present the results of morphological, compositional, and electrical characterization of the Ga2O3 nanowires, including the measurements on photoconductance and transient time. Our results show that highly oriented, dense and long Ga2O3 nanowires can be grown directly on the surface of silicon. The Ga2O3 nanowires, with their inherent n-type characteristics formed a pn heterojunction when grown on silicon. The heterojunction showed rectifying characteristics and excellent UV photoresponse

The Growth of Ga2O3 Nanowires on Silicon for Ultraviolet Photodetector

We investigated the effect of silver catalysts to enhance the growth of Ga2O3 nanowires. The growth of Ga2O3 nanowires on a P+-Si (100) substrate was demonstrated by using a thermal oxidation technique at high temperatures (~1000 °C) in the presence of a thin silver film that serves as a catalyst layer. We present the results of morphological, compositional, and electrical characterization of the Ga2O3 nanowires, including the measurements on photoconductance and transient time. Our results show that highly oriented, dense and long Ga2O3 nanowires can be grown directly on the surface of silicon. The Ga2O3 nanowires, with their inherent n-type characteristics formed a pn heterojunction when grown on silicon. The heterojunction showed rectifying characteristics and excellent UV photoresponse