Browsing by Author "Miranda, Andrea"

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    A Comprehensive Investigation of Polymer Binder Properties in Silicon Anodes for Lithium-Ion Batteries
    (2019-04-18) Miranda, Andrea; Verduzco, Rafael
    Energy storage technologies with increased energy densities and lifetimes are needed for the advancement of electric and hybrid electric vehicles and storage of intermittent renewable energy, among other technologies with significant energy needs. High capacity anode materials that can alloy with lithium, such as silicon, hold great promise towards advancing the energy density of lithium-ion batteries, a major component of the energy storage sector. However, silicon anodes undergo catastrophic volumetric expansion as lithium ions react with silicon in the anode resulting in silicon particle fracture, delamination, and disruption of the electrical network in the electrode during cycling, eventually resulting in failure. One method to address failure of silicon anodes is through the development of novel polymeric binders, which can mitigate or prevent damage during cycling by suppressing cracking, adhering strongly to silicon and copper, and passivating the silicon anode surface. In this thesis, we explore the design, development, and characterization of novel polymeric binder materials for silicon anodes, in particular connecting physical properties of polymeric binders to specific design principles. In the first chapter, we review the development of novel polymeric binders with an emphasis on guiding design principles and characterization techniques. In the second chapter, we study a molecular weight series of high-modulus and high adhesion partially hydrolyzed polyacrylamide (HPAM) binders. Model and composite electrodes prepared with varying molecular weight of the polymer binder are analyzed to correlate physical properties to electrochemical behavior trends and failure modes of the binders. We attribute capacity decay in these materials due to poor lithium ion mobility, eventually leading to fraction and isolation of silicon. In another chapter, a series of conductive PEDOT:PSS conjugated polymer binders are crosslinked using three different chemistries and characterized with respect to mechanical properties, adhesion, electrochemical stability, cycling capacity and stability. Crosslinking is found to enhance performance, and poor cycling stability is attributed to poor adhesion to silicon and copper. This work systematically investigates and quantifies the physical properties of polymeric binders relevant to electrode stability and performance.
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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.
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    Tannic Acid as a Small-Molecule Binder for Silicon Anodes
    (American Chemical Society, 2020) Sarang, Kasturi T.; Li, Xiaoyi; Miranda, Andrea; Terlier, Tanguy; Oh, Eun-Suok; Verduzco, Rafael; Lutkenhaus, Jodie L.
    Increasing demand for portable electronic devices, electric vehicles, and grid scale energy storage has spurred interest in developing high-capacity rechargeable lithium-ion batteries (LIBs). Silicon is an abundantly available anode material that has a theoretical gravimetric capacity of 3579 mAh/g and a low operating potential of 0–1 V vs Li/Li+. However, silicon suffers from large volume variation (>300%) during lithiation and delithiation that leads to pulverization, causing delamination from the current collector and battery failure. These issues may be improved by using a binder that hydrogen bonds with the silicon nanoparticle surface. Here, we demonstrate the use of tannic acid, a natural polyphenol, as a binder for silicon anodes in lithium-ion batteries. Whereas the vast majority of silicon anode binders are high molecular weight polymers, tannic acid is explored here as a small molecule binder with abundant hydroxyl (−OH) groups (14.8 mmol of OH/g of tannic acid). This allows for the specific evaluation of hydrogen-bonding interactions toward effective binder performance without the consideration of particle bridging that occurs otherwise with high molecular weight polymers. The resultant silicon electrodes demonstrated a capacity of 850 mAh/g for 200 cycles and a higher capacity when compared to electrodes fabricated by using high molecular weight polymers such as poly(acrylic acid), sodium alginate, and poly(vinylidene fluoride). This work demonstrates that a small molecule with high hydrogen-bonding capability can be used a binder and provides insights into the behavior of small molecule binders for silicon anodes.
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    Two distinctive energy migration pathways of monolayer molecules on metal nanoparticle surfaces
    (Springer Nature, 2016) Li, Jiebo; Qian, Huifeng; Chen, Hailong; Zhao, Zhun; Yuan, Kaijun; Chen, Guangxu; Miranda, Andrea; Guo, Xunmin; Chen, Yajing; Zheng, Nanfeng; Wong, Michael S.; Zheng, Junrong
    Energy migrations at metal nanomaterial surfaces are fundamentally important to heterogeneous reactions. Here we report two distinctive energy migration pathways of monolayer adsorbate molecules on differently sized metal nanoparticle surfaces investigated with ultrafast vibrational spectroscopy. On a 5 nm platinum particle, within a few picoseconds the vibrational energy of a carbon monoxide adsorbate rapidly dissipates into the particle through electron/hole pair excitations, generating heat that quickly migrates on surface. In contrast, the lack of vibration-electron coupling on approximately 1 nm particles results in vibrational energy migration among adsorbates that occurs on a twenty times slower timescale. Further investigations reveal that the rapid carbon monoxide energy relaxation is also affected by the adsorption sites and the nature of the metal but to a lesser extent. These findings reflect the dependence of electron/vibration coupling on the metallic nature, size and surface site of nanoparticles and its significance in mediating energy relaxations and migrations on nanoparticle surfaces.