Bulletin of the American Physical Society
APS March Meeting 2013
Volume 58, Number 1
Monday–Friday, March 18–22, 2013; Baltimore, Maryland
Session C39: Focus Session: Materials for Electrochemical Energy Storage I |
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Sponsoring Units: DMP GERA FIAP DCOMP Chair: Apparao Rao, Clemson University Room: 348 |
Monday, March 18, 2013 2:30PM - 2:42PM |
C39.00001: Enhanced electrochemical performance of graphene modified LiFePO$_4$ as a cathode material for lithium ion batteries Kulwinder Singh Dhindsa, Balaji Prasad Mandal, Ming-Wei Lin, Maryam Nazri, Gholam Abbas Nazri, Vaman M. Naik, Prem Vaishnava, Ratna Naik, Zhixian Zhou We synthesized LiFePO$_4$/graphene nano-composites using a sol-gel method by adding water dispersed graphene oxide to the LiFePO$_4$ precursors during the synthesis. The graphene oxide was subsequently reduced to graphene by annealing the composite which was confirmed by Raman spectroscopy and X-ray Photoelectron spectroscopy. The electronic conductivity of the composite was found to be six orders of magnitude higher than that of pure LiFePO$_4$ Scanning Electron microscopy and Transmission electron microscopy images show LiFePO$_4$ particles are wrapped in uniformly distributed graphene sheets throughout the material forming a three dimensional conducting network. At low currents, (C/3), the capacity of the composite cathode reaches 160 mAh/g, which is very close to the theoretical limit. More significantly, the graphene wrapped LiFePO$_4$ shows a dramatically improved rate capability up to 27C, and excellent charge-discharge cycle stability over 500 stable cycles as compared to the pure LiFePO$_4$. [Preview Abstract] |
Monday, March 18, 2013 2:42PM - 2:54PM |
C39.00002: Multilayer Graphynes for Lithium Ion Battery Anode Hoonkyung Lee Graphynes, two-dimensional layers of \textit{sp}- and \textit{sp}$^{2}$-bonded carbon atoms, have recently received considerable attention because of their potential as new Dirac materials. Here, focusing on their large surface area, we explore the applicability of graphynes as lithium ion battery anodes through the first-principles density functional calculations. We have found that Li potential energies are in the range suitable to be used as anodes. Furthermore, the maximum composite of Li-intercalated multilayer $\alpha $- and $\gamma $-graphynes is found to be C$_{6}$Li$_{3}$, which corresponds to a specific capacity of 1117 mAh g$^{-1}$, twice as large as the previous theoretical prediction for graphynes. The volumetric capacity of Li-intercalated multilayer $\alpha $- and $\gamma $-graphynes is 1364 and 1589 mAh cm$^{-3}$, respectively. Both specific and volumetric capacities of Li-intercalated graphynes are significantly larger than the corresponding value of graphite, from which we conclude that multilayer graphynes can serve as high-capacity lithium ion battery anodes. [Preview Abstract] |
Monday, March 18, 2013 2:54PM - 3:06PM |
C39.00003: Evaluating and enhancing quantum capacitance in graphene-based electrodes from first principles Tadashi Ogitsu, Minoru Otani, Jonathan Lee, Michael Bagge-Hansen, Juergen Biener, Brandon Wood Graphene derivatives are attractive as supercapacitor electrodes because they are lightweight, chemically inert, have high surface area and conductivity, and are stable in electrolyte solutions. Nevertheless, devising reliable strategies for improving energy density relies on an understanding of the specific factors that control electrode performance. We use density-functional theory calculations of pristine and defective graphene to extract quantum capacitance, as well as to identify specific limiting factors. The effect of structural point defects and strain-related morphological changes on the density of states is also evaluated. The results are combined with predicted and measured \emph{in situ} X-ray absorption spectra in order to give insight into the structural and chemical features present in synthesized carbon aerogel samples. [Preview Abstract] |
Monday, March 18, 2013 3:06PM - 3:42PM |
C39.00004: Architectures for Nanostructured Batteries Invited Speaker: Gary Rubloff Heterogeneous nanostructures offer profound opportunities for advancement in electrochemical energy storage, particularly with regard to power. However, their design and integration must balance ion transport, electron transport, and stability under charge/discharge cycling, involving fundamental physical, chemical and electrochemical mechanisms at nano length scales and across disparate time scales. In our group and in our DOE Energy Frontier Research Center (www.efrc.umd.edu) we have investigated single nanostructures and regular nanostructure arrays as batteries, electrochemical capacitors, and electrostatic capacitors to understand limiting mechanisms, using a variety of synthesis and characterization strategies. Primary lithiation pathways in heterogeneous nanostructures have been observed to include surface, interface, and both isotropic and anisotropic diffusion, depending on materials. Integrating current collection layers at the nano scale with active ion storage layers enhances power and can improve stability during cycling. For densely packed nanostructures as required for storage applications, we investigate both ``regular'' and ``random'' architectures consistent with transport requirements for spatial connectivity. Such configurations raise further important questions at the meso scale, such as dynamic ion and electron transport in narrow and tortuous channels, and the role of defect structures and their evolution during charge cycling. [Preview Abstract] |
Monday, March 18, 2013 3:42PM - 3:54PM |
C39.00005: Electrochemistry of ion inserted vanadium oxide nanosheets Marc Pomeroy, Shaola Ren, Qifan Yuan, Victoria Soghomonian Electrochemical energy storage is becoming increasingly important for its high specific power and quick charge and discharge rates. We investigate the electrical properties of hydrothermally synthesized vanadium oxide nanosheets as potential anode component of an electrochemical capacitor. The room temperature resistivity of the as-synthesized and pristine vanadium oxide nanosheets is around 10\textasciicircum 7 ohm-cm, and variable temperature measurements indicate the semiconducting behavior of the material. Electrodes are fabricated from the nanosheets, and inserted into appropriate chloride solutions of Li, Na and ammonium. Room temperature voltammetry in the solutions are recorded and provide a measure of stored energy relative to each cation. Scanning electron micrographs obtained before and after various cyclic voltammograms provides a visual measure of nanosheet stability and a correlation to its electrochemical activity. Micrographs show that the material is robust towards Li insertion, but after several cycles of ammonium insertion, degradation occurs. Degradation upon Na insertion is minimal. These comparative studies shed light on the interactions between ions and metal oxide nanosheets. [Preview Abstract] |
Monday, March 18, 2013 3:54PM - 4:06PM |
C39.00006: Redox electrodes comprised of polymer-modified carbon nanomaterials Mark Roberts, Robert Emmett, Mehmet Karakaya, Ramakrishna Podila, Apparao Rao A shift in how we generate and use electricity requires new energy storage materials and systems compatible with hybrid electric transportation and the integration of renewable energy sources. Supercapacitors provide a solution to these needs by combining the high power, rapid switching, and exceptional cycle life of a capacitor with the high energy density of a battery. Our research brings together nanotechnology and materials chemistry to address the limitations of electrode materials. Paper electrodes fabricated with various forms of carbon nanomaterials, such as nanotubes, are modified with redox-polymers to increase the electrode's energy density while maintaining rapid discharge rates. In these systems, the carbon nanomaterials provide the high surface area, electrical conductivity, nanoscale and porosity, while the redox polymers provide a mechanism for charge storage through Faradaic charge transfer. The design of redox polymers and their incorporation into nanomaterial electrodes will be discussed with a focus on enabling high power and high energy density electrodes. [Preview Abstract] |
Monday, March 18, 2013 4:06PM - 4:18PM |
C39.00007: Thin films with transvers concentration gradient as a model system to study core-shell cathodes for lithium ion batteries Shintaro Yasui, Zhi-peng Li, Joysurya Basu, Dmitry Ruzmetov, Leonid Bendersky, Ichiro Takeuchi, Alec Talin Recently it has been reported that heterogeneous structures of cathode materials for high-energy, high-power lithium-ion batteries have improved electrochemical properties, especially thermal stability. As an example, the spherical core-shell (or concentration-gradient) cathode particles with a Ni-rich core and a Mn-rich shell of Li(Ni$_{\mathrm{0.8}}$Co$_{\mathrm{0.1}}$Mn$_{\mathrm{0.1}})$O$_{\mathrm{2}}$ have better retention of capacity in comparison to uniform materials1. In this work the Li(Ni,Mn)O$_{\mathrm{2}}$ thin films with transverse compositional gradients were used as a model system to investigate and understand the reported improvements. Preparation of the films by multi-target pulse lased deposition (PLD) on single-crystal conductive Nb:SrTiO$_{\mathrm{3}}$ substrates allowed great compositional control and ability to deposit different compositional profiles, ranging from continuous to discreet variations of the Mn/Ni ratio. The film structures were studied by XRD and analytical TEM to correlate the structural and compositional variations. The films were tested for their electrochemical cycling performance and for the effect of cycling on structural degradations. [1] Chen, Z., Lee, D.-J., Sun, Y.-K. and Amine, K., MRS Bull. 36, 498--505 (2011). [Preview Abstract] |
Monday, March 18, 2013 4:18PM - 4:30PM |
C39.00008: Real time measurement of Al anode degradation in thin film batteries Marina Leite, Dmitry Ruzmetov, Zhipeng Li, Leonid Bendersky, A. Alec Talin Li-ion battery (LIB) anodes that alloy with Li, including Si, Ge, Sn, and Al have specific capacities that significantly exceed that of carbon-based intercalation anodes. However, the large volume expansion and contraction that accompany charging and discharging processes lead to large mechanical stresses that ultimately lead to loss of capacity and failure of the anodes. To better understand the failure mechanism, we cycle a thin film LIB with an Al anode in a scanning electron microscope to measure in real time the nucleation and growth of a highly strained (-44{\%}) Al-Li alloy. We use galvanostatic charging and discharging to control the rate of Li diffusion into the Al anode, and by collecting a series of SEM images in small time intervals we are able to directly correlate the nucleation events of Li-Al with specific peaks in the measured voltage. Based on these observations and ex situ transmission electron microscopy we develop a semi-quantitative description for the mechanism of Al anode degradation that could be extended to other alloy anode materials. [Preview Abstract] |
Monday, March 18, 2013 4:30PM - 4:42PM |
C39.00009: Carbon Nanotube-templated Polymer Single Crystals Serve as Controllable Spacers to Form Novel Battery Architectures Eric D. Laird, Christopher Y. Li One of the many challenges in battery cathode architectures lies in creating a porous structure with tunable features on the 10-100 nm length scale. Stable features of this size are desirable for engineered surface topology as well as charge storage applications. Few materials exist that can satisfy this requirement. Fewer still have high enough electron conductivity to be of use without adding an additional conducting phase. The ``nanohybrid shish kebab'' (NHSK) structure may be a solution to this obstacle. This physical functionalization technique for carbon nanotubes uses polymer single crystals grown from solution to produce a controllable spacer. In our previous work, it was shown that NHSKs can be controllably tuned to have average diameters ranging from 18 to 94 nm for single-walled carbon nanotubes. Films of these materials can easily be made free-standing and are highly flexible. Recent work in extending the functionality of these materials through the formation of ternary composites for battery applications will be presented. Pulsed electrodeposition of MnO2 onto the surfaces of these films forms an electrochemically active layer for lithium cells. High specific cathodic capacity has been observed in a rechargeable battery based on these materials. [Preview Abstract] |
Monday, March 18, 2013 4:42PM - 4:54PM |
C39.00010: Graphitic electrodes modified with boron and nitrogen for electrochemical energy storage enhancement Guoping Xiong, Rajib Paul, Ron Reifenberger, Timothy Fisher Electrodes based on carbon nanomaterials (carbon nanotubes or graphitic nanopetals) have been modified with boron (B) and nitrogen (N) through a facile microwave heating cycle. During the microwave heating, the electrodes are immersed in a precursor solution consisting of urea and boric acid dissolved in either water or methanol. After microwave heating and overnight vacuum drying, the electrodes are again heated in nitrogen to remove unreacted chemicals and to form C$_{x}$BN. Hydrogen plasma was then used to remove any residual boron oxide from the surface of the electrodes. Carbon nanotubes modified with B and N exhibited higher lithium storage capacity as compared to pure carbon nanotube electrodes. We note that the modification appears to produce a highly unexpected and substantial cycle-to-cycle improvement in battery capacity as the electrode cycles through hundreds of charge-discharge iterations. This process can be applied to other carbon-based electrodes, which themselves are recognized for their high performance, to add further improvements. [Preview Abstract] |
Monday, March 18, 2013 4:54PM - 5:06PM |
C39.00011: Rapid Synthesis of Few Layer Graphene Films and Their Electrochemical Behavior as Li-ion Battery Anode Lamuel David, Gurpreet Singh We study the process of graphene growth on Cu and Ni substrates subjected to rapid heating (approx. 8 $^{\circ}$C/sec) and cooling cycles (approx. 10 $^{\circ}$C/sec) in a modified atmospheric pressure chemical vapor deposition furnace. Electron microscopy followed by Raman spectroscopy demonstrated successful synthesis of large area few-layer graphene (FLG) films on both Cu and Ni substrates. The overall synthesis time was less than one hour. Further, the as-synthesized films were utilized as anode material and their electrochemical behavior was studied in a lithium half-cell configuration. FLG on Cu (Cu-G) showed reduced lithium-alloying capacity when compared with SLG, BLG and Bare-Cu suggesting its substrate protective nature (barrier to Li-ions). While FLG on Ni (Ni-G) showed better Li-cycling ability similar to that of other carbons suggesting that the presence of graphene edge planes (typical of Ni-G) is important in effective uptake and release of Li-ions in these materials. [Preview Abstract] |
Monday, March 18, 2013 5:06PM - 5:18PM |
C39.00012: A multi-physics study of Li-ion battery material Li$_{1+x}$Ti$_2$O$_4$ Tonghu Jiang, Michael Falk, Krishna Siva Shankar Rudraraju, Krishna Garikipati, Anton van der Ven Recently, lithium ion batteries have been subject to intense scientific study due to growing demand arising from their utilization in portable electronics, electric vehicles and other applications. Most cathode materials in lithium ion batteries involve a two-phase process during charging and discharging, and the rate of these processes is typically limited by the slow interface mobility. We have undertaken modeling regarding how lithium diffusion in the interface region affects the motion of the phase boundary. We have developed a multi-physics computational method suitable for predicting time evolution of the driven interface. In this method, we calculate formation energies and migration energy barriers by ab initio methods, which are then approximated by cluster expansions. Monte Carlo calculation is further employed to obtain thermodynamic and kinetic information, e.g., anisotropic interfacial energies, and mobilities, which are used to parameterize continuum modeling of the charging and discharging processes. We test this methodology on spinel Li$_{1+x}$Ti$_2$O$_4$. Elastic effects are incorporated into the calculations to determine the effect of variations in modulus and strain on stress concentrations and failure modes within the material. We acknowledge support by the National Science Foundation Cyber Discovery and Innovation Program under Award No. 1027765. [Preview Abstract] |
Monday, March 18, 2013 5:18PM - 5:30PM |
C39.00013: Novel Quinone-Based Couples for Flow Batteries Brian Huskinson, Saraf Nawar, Michael Aziz Flow batteries are of interest for low-cost grid-scale electrical energy storage in the face of rising electricity production from intermittent renewables like wind and solar. We will report on investigations of redox couples based on the reversible protonation of small organic molecules called quinones. We will report half-cell measurements of current density vs. potential for aqueous solutions of various quinones and hydroquinones in sulfuric acid, facilitated by a variety of electrocatalysts. For a subset of these we will report full fuel cell measurements as well. [Preview Abstract] |
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