Nanoengineered Ultralight and Robust All-Metal Cathode for High-Capacity, Stable Lithium-Oxygen Batteries.

The successful development of Li-O ₂ battery technology depends on resolving the issue of cathode corrosion by the discharge product (Li ₂ O ₂ ) and/or by the intermediates (LiO ₂ ) generated during cell cycling. As an important step toward this goal, we report for the first time the nanoporous Ni with a nanoengineered AuNi alloy surface directly attached to Ni foam as a new all-metal cathode system. Compared with other noncarbonaceous cathodes, the Li-O ₂ cell with an all-metal cathode is capable of operation with ultrahigh specific capacity (22,551 mAh g ^-1 at a current density of 1.0 A g ^-1 ) and long-term life (286 cycles). Furthermore, compared with the popularly used carbon cathode, the new all-metal cathode is advantageous because it does not show measurable reactivity toward Li ₂ O ₂ and/or LiO ₂ . As a result, extensive cyclability (40 cycles) with 87.7% Li ₂ O ₂ formation and decomposition was obtained. These superior properties are explained by the enhanced solvation-mediated formation of the discharge products as well as the tailored properties of the all-metal cathode, including intrinsic chemical stability, high specific surface area, highly porous structure, high conductivity, and superior mechanical stability.