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Synergetic Effect of Liquid and Solid Catalysts on the Energy Efficiency of Li–O2 Batteries: Cell Performances and Operando STEM Observations
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posted on 2020-02-24, 14:54 authored by Chen Hou, Jiuhui Han, Pan Liu, Gang Huang, Mingwei ChenThe
sluggish cathodic kinetics and lower energy efficiency, associated
with solid and insulating discharge products of Li2O2, are the key factors that prevent the practical implementation
of Li–O2 batteries (LOBs). Here we demonstrate that
the combination of the solid catalyst (RuO2) and soluble
redox mediator tetrathiafulvalene (TTF) exhibits a synergetic effect
in improving the cathodic kinetics and energy efficiency of LOBs by
reducing both charge and discharge overpotentials. Operando electron
microscopy observations and electrochemical measurements reveal that
RuO2 not only exhibits bifunctional catalysis for Li–O2 reactions but also benefits the catalytic efficiency of TTF.
Meanwhile, TTF plays an important role in activating the Li2O2 passivated RuO2 catalysts and in helping
RuO2 effectively oxidize the discharge products during
charging. The synergetic effect of solid and liquid catalysts, beyond
traditional bifunctional catalysis, obviously increases the cathodic
kinetics and round-trip energy efficiency of LOBs.