Browsing by Author "Galande, Charudatta"

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    Electrodes with three dimensional current collectors and methods of making the same
    (2017-02-14) Galande, Charudatta; Singh, Neelam; Khatiwada, Suman; Ajayan, Pulickel M.; Rice University; United States Patent and Trademark Office
    In some embodiments, the present disclosure pertains to methods of forming electrodes on a surface. In some embodiments, the formed electrodes have a three-dimensional current collector layer. In some embodiments, the present disclosure pertains to the formed electrodes. In some embodiments, the present disclosure pertains to energy storage devices that contain the formed electrodes.
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    Methods of preventing corrosion of surfaces by application of energy storage-conversion devices
    (2017-05-02) Galande, Charudatta; Singh, Neelam; Khatiwada, Suman; Ajayan, Pulickel M.; Rice University; United States Patent and Trademark Office
    The present disclosure pertains to methods of protecting a surface (e.g., a metal surface) from corrosion by conformably attaching a hybrid device comprising at least one multilayer energy storage device and at least one energy conversion device. In some embodiments, the multilayer energy storage device is formed by the following steps: (1) applying a non-solid negative electrode current collector composition above the surface to form an negative electrode current collector layer above the surface; (2) applying a non-solid negative electrode composition above the negative electrode current collector layer to form an negative electrode layer above the negative electrode current collector layer; (3) applying a non-solid electrically insulating composition above the negative electrode layer to form an electrically insulating layer above the negative electrode layer; (4) applying a non-solid positive electrode composition above the electrically insulating layer to form a positive electrode layer above the electrically insulating layer; and (5) applying a non-solid positive electrode current collector composition above the positive electrode layer to form a positive electrode current collector layer above the positive electrode layer.
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    Optical Studies on Functionalized Graphene Systems
    (2014-05-05) Galande, Charudatta; Ajayan, Pulickel M.; Weisman, R. Bruce; Yakobson, Boris I.; Mohite, Aditya D
    Graphene, the ‘wonder material’, has received a lot of attention for its excellent electronic properties. However, the lack of a band gap severely limits its use, especially in optoelectronic applications. Therefore, opening a band gap in Graphene and controllably modifying its band structure has long been the holy grail in the physics of Graphene. Of these methods, chemical functionalization offers the most degrees of freedom in controllably modifying the band structure of Graphene. Graphene Oxide (GO), the most widely studied chemical derivative of Graphene exhibits a host of optical phenomena such as broadband tunable fluorescence, multiphoton-induced absorption and emission etc. and presents an excellent platform for studying the effects of chemical functionalization on the optical properties of Graphene. In the present work, we first deal with the issue of origin of fluorescence in GO. It is argued that the broadband emission arises due to localized states created on the Graphene surface due to presence of functional groups, and not due to quantum confinement. Next, we attempt to find which of the many functional groups in GO contribute the most to the emission intensity. We find that the carbonyl and epoxide functional groups contribute the most to fluorescence. Further, we find that irradiation with a laser causes an enhancement in the PL of multilayered GO sheets by increasing the density of carbonyl functional groups on the basal plane. This interesting phenomenon is proposed to occur due to a reaction between the oxygen-functionalized basal plane and water molecules trapped between the GO multilayers. We have also developed a method for synthesizing large-area Graphene by chemical vapor deposition (CVD) using liquid precursors. This opens up a host of new possibilities for substitutional doping of Graphene by using liquid precursors containing the dopant atoms.
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    Paintable Battery
    (Springer, 2012) Singh, Neelam; Galande, Charudatta; Miranda, Andrea; Mathkar, Akshay; Gao, Wei; Reddy, Arava Leela Mohana; Vlad, Alexandru; Ajayan, Pulickel M.
    If the components of a battery, including electrodes, separator, electrolyte and the current collectors can be designed as paints and applied sequentially to build a complete battery, on any arbitrary surface, it would have significant impact on the design, implementation and integration of energy storage devices. Here, we establish a paradigm change in battery assembly by fabricating rechargeable Li-ion batteries solely by multi-step spray painting of its components on a variety of materials such as metals, glass, glazed ceramics and flexible polymer substrates. We also demonstrate the possibility of interconnected modular spray painted battery units to be coupled to energy conversion devices such as solar cells, with possibilities of building standalone energy capture-storage hybrid devices in different configurations.