@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 {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.} }