Rechargeable lithium-oxygen batteries are among the most promising energy storage devices for electric vehicle applications due to high theoretical specific energy; however, electrolyte stability, high charging overpotential, and poor cycle life hinder practical application. Carbon, commonly used as the cathode material in  Li-O2 batteries, is found to decomposition to Li2CO3 on charging above 3.0V due to attack by intermediates of Li2O2 oxidation.1-4 Li2CO3 formation increases with discharge/charge cycling resulting in high charging overpotentials and battery capacity fading.3  Bruce et al. have investigated several carbon-free cathode materials including porous Au, TiC, TiN and SiC.5-7 Li-O2 cells built with porous Au and TiC cathodes in DMSO-based electrolytes show good reversibility, low charging overpotentials, and capacity retentions of 95% and >98% after 100 cycles, respectively. To improve the electrical efficiency of Li-O2 batteries, redox mediators7 and various catalysts, such as metal oxides8-12, transition metal nitrides13-15 and noble metals,16,17 have been introduced into the cathodes of these batteries.           Understanding Li-O2 electrochemistry on various catalyst surfaces in non-aqueous electrolytes is important to improve performance. However, in-situ observations of Li-O2 electrochemical reactions on cathodes are still lacking. We report on in-situ AFM investigations of Li-O2 electrochemical reactions on Au, Pt, and Pd catalyst surfaces in DMSO-based electrolytes. Electrocatalysts can have a significant effect on product morphology and the formation and decomposition of lithium peroxide. We have found that the thickness of lithium peroxide formed on Pt and Pd is ~12 times greater than formed on Au. Additionally, the peroxide on Au and Pd displays a lower overpotential on charging. We have found that Pd is better than Pt and Au as an electrocatalyst for the Li-O2 reaction.  The influence of these different metal electrodes on the growth, morphology, and reaction mechanisms of Li2O2 will be discussed in the presentation.  References (1)       McCloskey, B.D.; Speidel, A.; Scheffler, R.; Miller, D.C.; Viswanathan, V.; Hummelsh�j, J.S.; N�rskov, J. K.; Luntz, A.C. J. Phys. Chem. Lett. 2012 , 3, 997-1001.(2)       Gallant, B. M.; Mitchell, R.R.; Kwabi, D.G.; Zhou, J.G.; Zuin, L.; Thompson, C.V.; Shao-Horn, Y. J. Phys. Chem. C 2102 , 116, 20800-20805.(3)       Thotiyl, M.M.O.; Freunberger, S.A.; Peng, Z.Q.; Bruce, P.G. J. Am. Chem. Soc. 2013 , 135, 494-500.(4)       Leskes, M.; Moore A.J.; Goward G.R.; Grey, C.P. J. Phys. Chem. C 2013 , 117, 26929-26939.(5)       Peng, Z.Q.; Freunberger, S.A.; Chen, Y.H.; Bruce, P.G. Science, 2012 , 337,563-566.(6)       Thotiyl, M.M.O.; Freunberger, S.A.; Peng, Z.Q.; Chen, Y.H.; Liu, Z.; Bruce, P.G. Nature Mater. 2013 , 12, 1050-1056.(7)       Chen, Y.H.; Freunberger, S.A.; Peng, Z.Q.; Fontaine, O.; Bruce, P.G. Nature Chem. 2013 , 5, 489-494.(8)       D�bart, A.; Bao, J.L.; Armstrong, G.; Bruce, P.G. J. Power Sources 2007 , 174, 1177-1182.(9)       Zeng, J.Q.; Nair, J.R.; Francia, C.; Bodoardo, S.; Penazzi, N. Int. J. Electrochem. Sci. 2013 , 8, 3912-3927.(10)     Black, R.; Lee, J.-H.; Adams, B.; Mims, C.A.; Nazar, L.F. Angew. Chem. Int. Ed. 2013 , 52, 392-396.(11)     Ryu, W.H.; Yoon, T.-H.; Song, S.H.; Jeon, S.K.; Park, Y.-J.; Kim, I.-D. Nano Lett. 2013 , 13, 4190-4197.(12)     Yilmaz, E.; Yogi, C.; Yamanaka, K.; Ohta, T.; Byon, H.R. Nano Lett. 2013 , 13, 4679-4684.(13)     Park, J.; Jun, Y.-S.; Lee, W.-R.; Gerbec, J.A.; See, K.A.; Stucky, G.D. Chem. Mater. 2013 , 25, 3770-3781.(14)     Li, F.J.; Ohnishi, R.; Yamada, Y.; Kubota, J.; Domen, K.; Yamada, A.; Zhou, H.S. Chem. Commun. 2013 , 49, 1175-1177.(15)     Dong, S.; Chen, X.; Zhang, K.; Gu, L.; Zhang, L.; Zhou, X.; Li, L.; Liu, Z.; Han, P.; Xu, H.; Yao, J.; Zhang, C.; Zhang, X.; Shang, C.; Cui, G.; Chen, L. Chem. Commun. 2011 , 47, 11291-11293.(16)     Lu, Y.-C.; Kwabi, D.G.; Yao, K.P.C.; Harding, J.R.; Zhou, J.; Zuin, L.; Shao-Horn, Y. Energy Environ. Sci. 2011 , 4, 2952-2958.(17)     Lu, Y.-C.; Gasteiger, H.A.; Shao-Horn, Y. J. Am. Chem. Soc. 2011 , 133, 19048-19051.

In-situ AFM investigations of the Li-O<sub>2</sub> electrochemical reaction on precious metal catalyst surfaces in DMSO-based electrolytes

248th National Meeting (2014)

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In-situ AFM investigations of the Li-O2 electrochemical reaction on precious metal catalyst surfaces in DMSO-based electrolytes

In-situ AFM investigations of the Li-O₂ electrochemical reaction on precious metal catalyst surfaces in DMSO-based electrolytes