Aprotic Li-O2 cells: Gas diffusion layer (GDL) as catalyst free cathode and tetraglyme/LiClO4 as electrolyte

High performing Li-O2 cells are assembled using a commercially available gas diffusion layer (GDL) as catalyst free cathode and tetraglyme/LiClO4 as aprotic electrolyte, and their electrochemical performances are investigated. The potential/time bound electrochemical characterization at different discharge rates and depths is performed along with ex situ analyses using techniques such as X-ray diffraction and FESEM. Among the two different GDLs investigated, the one with standard microporous layer is promising as high capacity cathode. Cell charge/discharge capability was evaluated and the results strongly support a discharge mechanism which mainly involves Li2O2 formation/dissolution at the cathode. The studies by XRD confirmed the existence of Li2O2 particles as the only detected product on the discharged cathode which is deposited and grown up at the surface as well as inside the microporous layer. The cell with GDL cathode maintains a very good cyclability under potential/time controlled mode with minimum amount of electrolyte decomposed products.