Showing papers by "K. M. Abraham published in 2015"

Prospects and Limits of Energy Storage in Batteries.

Abstract: Energy densities of Li ion batteries, limited by the capacities of cathode materials, must increase by a factor of 2 or more to give all-electric automobiles a 300 mile driving range on a single charge. Battery chemical couples with very low equivalent weights have to be sought to produce such batteries. Advanced Li ion batteries may not be able to meet this challenge in the near term. The state-of-the-art of Li ion batteries is discussed, and the challenges of developing ultrahigh energy density rechargeable batteries are identified. Examples of ultrahigh energy density battery chemical couples include Li/O2, Li/S, Li/metal halide, and Li/metal oxide systems. Future efforts are also expected to involve all-solid-state batteries with performance similar to their liquid electrolyte counterparts, biodegradable batteries to address environmental challenges, and low-cost long cycle-life batteries for large-scale energy storage. Ultimately, energy densities of electrochemical energy storage systems are limited...

A Study of the Influence of Lithium Salt Anions on Oxygen Reduction Reactions in Li-Air Batteries

Abstract: The influence of lithium salts on O2 reduction reactions (ORR) in 1, 2-dimethoxyethane (DME) and tetraethylene glycol dimethyl ether (TEGDME) has been investigated. Microelectrode studies in a series of tetrabutylammonium salt (TBA salt)/DME-based electrolytes showed that O2 solubility and diffusion coefficient are not significantly affected by the electrolyte anion. The ORR voltammograms on microelectrodes in these electrolytes exhibited steady-state limiting current behavior. In contrast, peak-shaped voltammograms were observed in Li+-conducting electrolytes suggesting a reduction of the effective electrode area by passivating ORR products as well as migration-diffusion control of the reactants at the microelectrode. FT-IR spectra have revealed that Li+ ions are solvated to form solvent separated ion pairs of the type Li+(DME)nPF6− and Li+(TEGDME)PF6− in LiPF6-based electrolytes. On the other hand, the contact ion pairs (DME)mLi+(CF3SO3−) and(TEGDME)Li+(CF3SO3−) appear to form in LiSO3CF3containing electrolytes. In the LiSO3CF3–based electrolytes the initial ORR product, superoxide (O2−), is stabilized in solution by forming [(DME)m-1(O2−)]Li+(CF3SO3−) and [(TEGDME)(O2−)]Li+(CF3SO3−) complexes. These soluble superoxide complexes are able to diffuse away from the electrode surface reaction sites to the bulk electrolyte in the electrode pores where they decompose to form Li2O2. This explains the higher capacity obtained in Li/O2 cells utilizing LiCF3SO3/TEGDME electrolytes. © 2015 The Electrochemical Society. [DOI: 10.1149/2.0841506jes] All rights reserved.

A high rate Li-rich layered MNC cathode material for lithium-ion batteries

Abstract: We report a high rate Li-rich layered manganese nickel cobalt (MNC) oxide cathode material of the composition 0.5Li2MnO3·0.5LiMn0.5Ni0.35Co0.15O2, termed Li-rich MNC cathode material, with discharge capacities of 200, 250, and 290 mA h g−1 at C, C/4 and C/20 rates, respectively, for Li-ion batteries. This high rate discharge performance combined with little capacity fade during long term cycling is unprecedented for this class of lithium ion (Li-ion) cathode materials. The exceptional electrochemistry of the Li-rich MNC in Li-ion cells is attributed to its open porous morphology and high electronic conductivity. The structure of the material investigated by means of X-ray diffraction (XRD), High Resolution Transmission Electron Microscopy (HRTEM) and X-ray Absorption Spectroscopy (XAS) combined with electrochemical data revealed that the porous morphology was effective in allowing electrolyte penetration through the particle grains in tandem with its high electronic conductivity to provide high Li+ transport for high rate discharge. Extended cycling behavior and structural phase transition of the new material were further examined through Field Emission Scanning Electron Microscopy (FESEM), XRD, XAS and HRTEM. The new Li-rich MNC cathode material could provide the next generation Li-ion batteries with specific energy exceeding 400 W h kg−1 or energy density over 1000 W h l−1.

A Search for the Optimum Lithium Rich Layered Metal Oxide Cathode Material for Li-Ion Batteries

Abstract: We report the results of a comprehensive study of the relationship between electrochemical performance in Li cells and chemical composition of a series of Li rich layered metal oxides of the general formula xLi2MnO3 · (1-x)LiMn0.33Ni0.33Co0.33O2 in which x = 0,1, 0.2, 0,3, 0.5 or 0.7, synthesized using the same method. In order to identify the cathode material having the optimum Li cell performance we first varied the ratio between Li2MnO3 and LiMO2 segments of the composite oxides while maintaining the same metal ratio residing within their LiMO2 portions. The materials with the overall composition 0.5Li2MnO3 · 0.5LiMO2 containing 0.5 mole of Li2MnO3 per mole of the composite metal oxide were found to be the optimum in terms of electrochemical performance. The electrochemical properties of these materials were further tuned by changing the relative amounts of Mn, Ni and Co in the LiMO2 segment to produce xLi2MnO3 · (1-x)LiMn0.50Ni0.35Co0.15O2 with enhanced capacities and rate capabilities. The rate capability of the lithium rich compound in which x = 0.3 was further increased by preparing electrodes with about 2 weight-percent multiwall carbon nanotube in the electrode. Lithium cells prepared with such electrodes were cycled at the 4C rate with little fade in capacity for over one hundred cycles.

Economic analysis of CNT lithium-ion battery manufacturing

Abstract: Development of safe, economically competitive, and environmentally responsible nano-enabled products is desirable to avoid unintended consequences. Given the environmental health and safety uncertainties associated with nanomaterials, additional precautions for exposure prevention may be required, although not regulated. Companies working with engineered nanomaterials may want to understand decision tradeoffs for the costs associated with increased levels of occupational safety and potential environmental impacts. Recent advances in nanotechnology have resulted in the development of advanced lithium nickel manganese cobalt (NMC) oxide batteries enhanced with multiwall carbon nanotubes (MWCNT). These batteries have a much greater energy density and product life than traditional lithium-ion batteries. A stochastic process-based cost model (PBCM) is developed to investigate the cost drivers for manufacture of MWCNT NMC batteries targeted for satellite and computer applications. Various levels of occupational safety protection (low, medium and high assumed) are analyzed to determine their effect on total manufacturing cost. The results show that MWCNT cost has the highest impact on total unit cost for production of satellite batteries, whereas cycle time has the highest impact on the unit cost of computer batteries. The mixing step contributes the most to the total unit cost for both satellite and computer MWCNT NMC lithium-ion batteries due to the inclusion of MWCNT costs in the mixing step. The process-based cost model developed in this work not only offers estimation of the economic drivers associated with the MWCNT NMC battery manufacturing, but also allows consideration of strategies to reduce costs. Results contribute to safer manufacturing practices for CNT lithium-ion batteries for low and high production volume applications (satellites and portable computers, respectively).

Layered metal oxide cathode material for lithium ion batteries

Abstract: The invention provides a cathode material for Ll-ion batteries. The material has the formula of 0.5Li 2 Mn0 3 -0.5LiMn 0.5 Ni 0.35 Co 0.15 0 2 . The material was synthesized using the "self-ignition combustion" method, which previously has not been used for the preparation of Li-rich layered metal oxides. The cathode material exhibits capacities of 290, 250, and 200 mAh/g at discharge rates of C/20, C/4 and C rates, respectively. Moreover, the new material exhibits high rate cycling ability with little or no capacity fade for over 100 cycles demonstrated at a series of rates from C/20 to 2C rates for electrodes loadings of 7-8 mg/cm 2 .

Electrochemical Energy Summit An International Summit in Support of Societal Energy Needs

Abstract: Electrochemical Energy Summit--An International Summit in Support of Societal Energy Needs Report Title On October 10 to 12, 2011, The Electrochemical Society, Inc., held its first Electrochemical Energy Summit, E2S. The objective of the first E2S was to bring policy makers and researchers together to discuss what the world’s energy needs are and what answers electrochemical science and technology can provide. The first E2S consisted of a poster session, which provided an opportunity for scientists to present their solutions, a panel discussion made of representatives from the U.S.A., Japan, and Germany and a plenary lecture. These proceedings present a selected number of papers presented as posters at the summit. Conference Name: Electrochemical Energy Summit 2011 Conference Date: October 10, 2011 Electrochemical Energy Summit – An International Summit in Support of Societal Energy Needs C. Bock National Research Council Canada Ottawa, Ontario, Canada J. Leddy The University of Iowa Iowa City, Iowa, USA Editors: Sponsoring Divisions: Published by The Electrochemical Society 65 South Main Street, Building D Pennington, NJ 08534-2839, USA tel 609 737 1902 fax 609 737 2743 www.electrochem.org TM Vol. 41, No. 31 All Divisions Copyright 2012 by The Electrochemical Society. All rights reserved. This book has been registered with Copyright Clearance Center. For further information, please contact the Copyright Clearance Center, Salem, Massachusetts. Published by: The Electrochemical Society 65 South Main Street Pennington, New Jersey 08534-2839, USA Telephone 609.737.1902 Fax 609.737.2743 e-mail: ecs@electrochem.org Web: www.electrochem.org ISSN 1938-6737 (online) ISSN 1938-5862 (print) ISSN 2151-2051 (cd-rom) ISBN 978-1-56677-971-5 (PDF) ISBN 978-1-60768-330-8 (Softcover) Printed in the United States of America.