N-methyl-2-pyrrolidone as a solvent for the non-aqueous electrolyte of rechargeable Li-air batteries

摘要

The instability of solvent molecules toward oxygen reduction species is the main reason for the performance deterioration of rechargeable Li-air batteries. Identifying the appropriate electrolyte solvents is one prerequisite for the application of Li-air batteries. In this article, we study N-methyl-2-pyrrodione (NMP) as a solvent for the non-aqueous electrolyte of Li-air batteries. Oxygen reduction reactions (ORRs) and oxygen oxidation reactions (OERs) are investigated on Au and glassy carbon (GC) electrodes in NMP-based terabutylammonium perchlorate (TBAClO_4) and lithium perchlorate (LiClO_4) electrolyte solutions using the cyclic voltammetry method. Raman and X-ray photoemission spectra (XPS) are used to detect the species on the electrode surface during cell cycles. The results show that while the one-electron O_2/O_2 reversible couples are observed in TBAClO_4/NMP, in presence of Li ion, the initially formed LiO_2 generated by one-electron transfer process decomposes to Li_2O_2. As the predomi nant discharge products, Li_2O_2 decomposes during the recharge processes. The cells using NMP-based electrolytes exhibit good cycle performance, and the first cycle efficiency is approximately 97%. Although the decomposition of NMP occurs on the air electrode surface during the cells recharge, the increased chemical stability against oxygen reduction species offer NMP-based electrolytes as potential candidates for rechargeable Li-air batteries electrolytes.