Abstract
The development of highly efficient catalysts in the cathodes of rechargeable Li-O2 batteries is a consider-able challenge.To enhance the electrochemical performance of the Li-O2 battery,it is essential to choose a suitable catalyst material.Copper selenide(CuSe)is considered as a more promising cathode catalyst material for Li-O2 battery due to its better conductivity and rich electrochemical active sites.However,its electrochemical reaction and fundamental catalytic mechanism remain unclear till now.Herein,in-situ environmental transmission electron microscopy technique was used to study the catalysis mechanism of the CuSe nanosheets in Li-O2 batteries during discharge and charge processes.It is found that Li2O was formed and decomposed around the ultrafine-grained Cu during the discharge and charge processes,respectively,demonstrating excellent cycling.This indicate that the freshly formed ultrafine-grained Cu in the conversion reaction catalyzed the latter four-electron-transfer oxygen reduction reaction,leading to the formation of Li2O.Our study provides important understanding of the electrochemistry of the Li-O2 nanobatteries,which will aid the development of high-performance Li-O2 batteries for energy storage applications.
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