Carbon-sulfur double bond electrolyte additives as redox mediator for lithium-oxygen batteries

Abstract

Lithium-oxygen battery (LOB) has extremely high theoretical energy density (about 5–10 times as that of lithium-ion battery), which is being studied widely. At present, LOB still face many severe challenges such as low energy conversion efficiency, poor rate performance and short cycling life, which seriously restricts its development and practical applications. This paper proposed a type of carbon-sulfuric electrolyte additive: thioacetamide (TTA) and dimethyl thiocarbamoyl chloride (DMTCC) for LOB. With the strong electronegativity of the carbon-nitrogen bond and the carbon-sulfur double bond, Li2O2 grows in liquid phase easily on the electrode surface, which significantly reduced the reaction potential. Both of the additives result in the good performance at a specific concentration, with lower charging potential and improved cycling properties. It is believed that the carbon-sulfuric electrolyte additive will benefit a homogeneous catalytic mode, which accelerates the decomposition of Li2O2 and realizes the reduction of the oxygen evolution reactions (OER) reaction potential and the improvement of comprehensive performance.