In Li-O₂ battery system, precipitation of Li₂O₂ passivate the cathode’s surface during charging, what terminates electrochemical reaction and limit the cell capacity.^1,2 In the charging process, oxidation of the non-conductive Li peroxide precipitants requires high over-potentials, in which solution species may be readily oxidized. In order to address these shortcomings, many researchers^3,4 tried to modify the morphology, size, and crystallinity of Li₂O₂ during its generation by electro-catalysis and the use of composite cathodes comprising nano-materials.

Efforts have been made to decrease the overpotential at the formation and decomposition of Li₂O₂, by identifying catalysts that can control the morphology of Li₂O₂. Morphological control makes Li₂O₂ easier to decompose on oxygen evolution reaction (OER). Herein, we show that silver nanowires as cathode materials for Li–oxygen batteries. AgNW greatly reduce the charging over-potential needed for OER at the solution/electrode interface and are more effective than silver nanoparticles (AgNP). AgNW deliver reversible Li₂O₂ formation/decomposition on discharge/charge with an average charging potential of ∼3.4 V without electrolyte solution decomposition after 50 cycles. We confirmed that unique Li₂O₂ structure can promote the decomposition at low charge potential upon oxygen evolution reaction leading to high electrical efficiently of Li-air batteries up to 83.4%.

References

 

(1)     Kraytsberg, A.; Ein-Eli, Y. J. Power Sources 2011, 196, 886–893.

(2)      Viswanathan, V.; Thygesen, K. S.; Hummelshoj, J. S.; Norskov, J. K.; Girishkumar, G.; McCloskey, B. D.; Luntz, A. C. J. Chem. Phys. 2011, 135, 214704 (1–10).

(3)      Mitchell, R. R.; Gallant, B. M.; Shao-Horn, Y.; Thompson, C. V. J. Phys. Chem. Lett. 2013, 4, 1060–1064.

(4)      Adams, B. D.; Radtke, C.; Black, R.; Trudeau, M. L.; Zaghib, K.; Nazar, L. F. Energy Environ. Sci. 2013, 6, 1772–1778.