Vertically Aligned Two-Dimensional Graphene-Metal Hydroxide Hybrid Arrays for Li-O2Batteries.
Lithium oxygen batteries (LOBs) are a very promising upcoming technology which, however, still suffers from low lifespan and dramatic capacities fading. Solid discharge products increase the contact resistance and block the electrochemically active electrodes. The resulting high oxidative potentials and formation of Li2CO3due to electrolyte and carbon electrode decomposition at the positive electrode lead to irreversible deactivation of oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) sites. Here we demonstrate a facile strategy for the scalable production of a new electrode structure constituted of vertically aligned carbon nanosheets and metal hydroxide (M(OH)x@CNS) hybrid arrays, integrating both favorable ORR and OER active materials to construct bifunctional catalysts for LOBs. Excellent lithium-oxygen battery properties with high specific capacity of 5403 mAh g-1and 12123 mAh g-1referenced to the carbon and M(OH)xweight, respectively, long cyclability, and low charge potentials are achieved in the resulting M(OH)x@CNS cathode architecture. The properties are explained by improved O2/ion transport properties and spatially limited precipitation of Li2O2nanoparticles inside interstitial cavities resulting in high reversibility. The strategy of creating ORR and OER bifunctional catalysts in a single conductive hybrid component may pave the way to new cathode architectures for metal air batteries.
Department of Colloid Chemistry, Research Campus Golm, Max Planck Institute of Colloids and Interfaces , Am Mühlenberg 1, 14476 Potsdam, Germany.
Jixin
J
Zhu
Chair of Technical Electrochemistry, Technische Universität München , Lichtenbergstrasse 4, 85748 Garching, Germany.
Michael
M
Metzger
Department of Colloid Chemistry, Research Campus Golm, Max Planck Institute of Colloids and Interfaces , Am Mühlenberg 1, 14476 Potsdam, Germany.
Markus
M
Antonietti
Department of Colloid Chemistry, Research Campus Golm, Max Planck Institute of Colloids and Interfaces , Am Mühlenberg 1, 14476 Potsdam, Germany.
Tim-Patrick
TP
Fellinger
bifunctional electrocatalysts; carbon nanosheets; lithium-O2 battery; metal hydroxide