Enhanced capacity of LiCoO2 and graphite battery by using methylene methanedisulfonate as electrolyte additive

Lithium cobalt oxide (LiCoO2) and graphite-based Li-ion batteries have been widely applied for consumer electronics because of the long cycle life and easy preparation. However, the limited capacity for traditional materials hampers the practical application for high energy-density battery. Conventional electrolyte system could not satisfy the need for high-capacity materials. Here, methylene methanedisulfonate (MMDS) was chosen as electrolyte additive for enhancing the available capacity for LiCoO2 and graphite-based battery. The effect of MMDS on the LiCoO2 cathode and graphite anode was investigated via multi electrochemical methods. It was found that the capacity for cells with MMDS electrolyte additive increases (from 142.6 mAh g(-1) for pristine to 193.4 mAh g(-1) on LiCoO2/Li battery, from 275.5 mAh g(-1 )for pristine to 407.0 mAh g(-1) on graphite/Li battery). The experimental results indicate that improved capacity by MMDS electrolyte additive can be attributable to the stabilized interface on both cathode and anode sides, leading to superior interfacial Li+ kinetics and mitigated bulk structural degradation, which was further confirmed by the ex-situ electrochemical and structural characterization.