Methylene Methanedisulfonate (MMDS) as a Novel SEI Forming Additive on Anode for Lithium Ion Batteries

In this paper, methylene methanedisulfonate (MMDS) is reported as a novel solid electrolyte interphase (SEI) forming additive in propylene carbonate (PC) based electrolyte on graphite anode for lithium ion batteries. The effects of MMDS with PC-based electrolyte system of the electrochemical behaviors on graphite anode are investigated via combination of multi electrochemical methods, including charge/discharge test, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and computation. Theoretical calculation result indicates that MMDS is preferably reduced on graphite to PC solvent, which is further supported by the CV experimental results. Charge-discharge test of Li/MCMB half cells and MCMB/LiMn2O4 full cells verify that the use of MMDS can successfully suppress the decomposition of PC and exfoliation of graphite. EIS technique is employed to monitor the SEI forming processes, indicating effective surface layer is formed on the graphite anode with incorporation of MMDS in PC-based electrolyte. The morphology, structure, and chemical nature of the formed SEI via MMDS participating are investigated by ex-situ analytical techniques, including SEM, TEM/EDS, and FTIR/ATR.