@article {79, title = {A mesoporous catalytic membrane architecture for lithium-oxygen battery systems}, journal = {Nano LettNano Lett}, volume = {15}, number = {1}, year = {2015}, note = {Ryu, Won-Hee
Gittleson, Forrest S
Schwab, Mark
Goh, Tenghooi
Taylor, Andre D
eng
Research Support, Non-U.S. Gov{\textquoteright}t
Research Support, U.S. Gov{\textquoteright}t, Non-P.H.S.
2014/12/30 06:00
Nano Lett. 2015 Jan 14;15(1):434-41. doi: 10.1021/nl503760n. Epub 2014 Dec 30.}, month = {Jan 14}, pages = {434-41}, abstract = {

Controlling the mesoscale geometric configuration of catalysts on the oxygen electrode is an effective strategy to achieve high reversibility and efficiency in Li-O2 batteries. Here we introduce a new Li-O2 cell architecture that employs a catalytic polymer-based membrane between the oxygen electrode and the separator. The catalytic membrane was prepared by immobilization of Pd nanoparticles on a polyacrylonitrile (PAN) nanofiber membrane and is adjacent to a carbon nanotube electrode loaded with Ru nanoparticles. During oxide product formation, the insulating PAN polymer scaffold restricts direct electron transfer to the Pd catalyst particles and prevents the direct blockage of Pd catalytic sites. The modified Li-O2 battery with a catalytic membrane showed a stable cyclability for 60 cycles with a capacity of 1000 mAh/g and a reduced degree of polarization ( approximately 0.3 V) compared to cells without a catalytic membrane. We demonstrate the effects of a catalytic membrane on the reaction characteristics associated with morphological and structural features of the discharge products via detailed ex situ characterization.

}, keywords = {catalyst, electrospinning, Lithium-oxygen batteries, mesoporous polymer membrane, oxygen evolution reaction}, isbn = {1530-6992 (Electronic)
1530-6984 (Linking)}, doi = {10.1021/nl503760n}, author = {Ryu, W. H. and Gittleson, F. S. and Schwab, M. and Goh, T. and Taylor, A. D.} } @article {65, title = {Catalyst and electrolyte synergy in Li-O2 batteries}, journal = {Phys Chem Chem PhysPhys Chem Chem Phys}, volume = {16}, number = {7}, year = {2014}, note = {Gittleson, Forrest S
Sekol, Ryan C
Doubek, Gustavo
Linardi, Marcelo
Taylor, Andre D
eng
England
2014/01/11 06:00
Phys Chem Chem Phys. 2014 Feb 21;16(7):3230-7. doi: 10.1039/c3cp54555e. Epub 2014 Jan 10.}, month = {Feb 21}, pages = {3230-7}, abstract = {

Understanding the interactions between catalyst and electrolyte in Li-O2 systems is crucial to improving capacities, efficiencies, and cycle life. In this study, supported noble metal catalysts Pt/C, Pd/C, and Au/C were paired with popular Li-O2 electrolyte solvents dimethoxyethane (DME), tetraglyme (TEGDME), and dimethyl sulfoxide (DMSO). The effects of these combinations on stability, kinetics, and activity were assessed. We show evidence of a synergistic effect between Pt and Pd catalysts and a DMSO-based electrolyte which enhances the kinetics of oxygen reduction and evolution reactions. DME and TEGDME are more prone to decomposition and less kinetically favorable for oxygen reduction and evolution than DMSO. While the order of oxygen reduction onset potentials with each catalyst was found to be consistent across electrolyte (Pd \> Pt \> Au), larger overpotentials with DME and TEGDME, and negative shifts in onset after only five cycles favor the stability of a DMSO electrolyte. Full cell cycling experiments confirm that catalyst-DMSO combinations produce up to 9 times higher discharge capacities than the same with TEGDME after 20 cycles ( approximately 707.4 vs. 78.8 mA h g(-1) with Pd/C). Ex situ EDS and in situ EIS analyses of resistive species in the cathode suggest that improvements in capacity with DMSO are due to a combination of greater electrolyte conductivity and catalyst synergies. Our findings demonstrate that co-selection of catalyst and electrolyte is necessary to exploit chemical synergies and improve the performance of Li-O2 cells.

}, isbn = {1463-9084 (Electronic)
1463-9076 (Linking)}, doi = {10.1039/C3CP54555E}, author = {Gittleson, F. S. and Sekol, R. C. and Doubek, G. and Linardi, M. and Taylor, A. D.} } @article {64, title = {Operando observation of the gold-electrolyte interface in Li-O2 batteries}, journal = {ACS Appl Mater InterfacesACS Appl Mater Interfaces}, volume = {6}, number = {21}, year = {2014}, note = {Gittleson, Forrest S
Ryu, Won-Hee
Taylor, Andre D
eng
Research Support, Non-U.S. Gov{\textquoteright}t
Research Support, U.S. Gov{\textquoteright}t, Non-P.H.S.
2014/10/16 06:00
ACS Appl Mater Interfaces. 2014 Nov 12;6(21):19017-25. doi: 10.1021/am504900k. Epub 2014 Oct 31.}, month = {Nov 12}, pages = {19017-25}, abstract = {

Observing the cathode interface in Li-O2 batteries during cycling is necessary to improve our understanding of discharge product formation and evolution in practical cells. In this work a gold electrode surface is monitored by operando surface-enhanced Raman spectroscopy during typical discharge and charge cycling. During discharge, we observe the precipitation of stable and reversible lithium superoxide (LiO2), in contrast to reports that suggest it is a mere intermediate in the formation of lithium peroxide (Li(2)O2). Some LiO2 is further reduced to Li(2)O2 producing a coating of insulating discharge products that renders the gold electrode inactive. Upon charging, a superficial layer of these species ( approximately 1 nm) are preferentially oxidized at low overpotentials (\<0.6 V), leaving residual products in poor contact with the electrode surface. In situ electrochemical impedance spectroscopy is also used to distinguish between LiO2 and Li(2)O2 products using frequency-dependent responses and to correlate their reduction and oxidation potentials to the accepted mechanism of Li(2)O2 formation. These operando and in situ studies of the oxygen electrode interface, coupled with ex situ characterization, illustrate that the composition of discharge products and their proximity to the catalytic surface are important factors in the reversibility of Li-O2 cells.

}, keywords = {electrochemical impedance spectroscopy, Li2O2, LiO2, lithium-air, lithium-oxygen, Raman spectroscopy, Sers}, isbn = {1944-8252 (Electronic)
1944-8244 (Linking)}, doi = {10.1021/am504900k}, author = {Gittleson, F. S. and Ryu, W. H. and Taylor, A. D.} } @article {63, title = {Improving the assembly speed, quality, and tunability of thin conductive multilayers}, journal = {ACS NanoACS Nano}, volume = {6}, number = {5}, year = {2012}, note = {Gittleson, Forrest S
Kohn, David J
Li, Xiaokai
Taylor, Andre D
eng
2012/04/21 06:00
ACS Nano. 2012 May 22;6(5):3703-11. doi: 10.1021/nn204384f. Epub 2012 May 7.}, month = {May 22}, pages = {3703-11}, abstract = {While inhomogeneous thin conductive films have been sought after for their flexibility, transparency, and strength, poor control in the processing of these materials has restricted their application. The versatile layer-by-layer assembly technique allows greater control over film deposition, but even this has been hampered by the traditional dip-coating method. Here, we employ a fully automated spin-spray layer-by-layer system (SSLbL) to rapidly produce high-quality, tunable multilayer films. With bilayer deposition cycle times as low as 13 s (~50\% of previously reported) and thorough characterization of film conductance in the near percolation region, we show that SSLbL permits nanolevel control over film growth and efficient formation of a conducting network not available with other methods of multilayer deposition. The multitude of variables from spray time, to spin rate, to active drying available with SSLbL makes films generated by this technique inherently more tunable and expands the opportunity for optimization and application of composite multilayers. A comparison of several polymer-CNT systems deposited by both spin-spray and dip-coating exemplifies the potential of SSLbL assembly to allow for rapid screening of multilayer films. Ultrathin polymer-CNT multilayers assembled by SSLbL were also evaluated as lithium-ion battery electrodes, emphasizing the practical application of this technique.}, isbn = {1936-086X (Electronic)
1936-0851 (Linking)}, author = {Gittleson, F. S. and Kohn, D. J. and Li, X. and Taylor, A. D.} }