Key Words:Cobalt compounds;Binders - Cathodes - Cobalt deposits - Electrolytic reduction - Lithium - Lithium batteries - Lithium compounds - Nanosheets - Oxygen - Secondary batteries;Catalytic active sites - Cobalt oxides - Cyclic lives - Discharge specific capacity - Nanoarrays - Over potential - Oxygen evolution reaction - Oxygen reduction reaction

Abstract:Two shapes of Co<inf>3</inf>O<inf>4</inf>nanoarrays (i.e., nanosheets, nanowires) with different densities of exposed catalytic active sites were synthesized through a facile hydrothermal method on Ni foam substrates and tested as the binder/carbon free and free-standing cathodes for Li–O<inf>2</inf>batteries. Particularly, the single crystalline feature of Co<inf>3</inf>O<inf>4</inf>nanosheets with a predominant high reactivity {112} exposed crystal plane and hierarchical porous nanostructure displayed better catalytic performance for both oxygen reduction reaction (during discharge process) and oxygen evolution reaction (during charge process). Li–O<inf>2</inf>battery with Co<inf>3</inf>O<inf>4</inf>nanosheets cathode exhibited a higher discharge specific capacity (965 mAh g⁻¹), lower discharge/charge over-potential and better cycling performance over 63 cycles at 100 mA g⁻¹with the specific capacity limited at 300 mAh g⁻¹. The superior catalytic performance of Co<inf>3</inf>O<inf>4</inf>nanosheets cathode is ascribed to the enlarging specific area and increasing the exposed Co³⁺catalytic active sites within predominant {112} crystal plane which plays the key role in determining the adsorption energy for the reactants, enabling high round-trip efficiency and cyclic life.<br/> © 2018

Volume:30

Issue:无

Translation or Not:no