Effect of methylene methanedisulfonate as an additive on the cycling performance of spinel lithium titanate electrode

• MMDS used as additive to improve cycling performance of the Li4Ti5O12/Li cells.
• A SEI film can be formed using MMDS in the electrolyte above 1 V.
• Sulfur-containing species is the main component of the SEI formed by MMDS.

In order to overcome the poor cyclability of lithium-ion batteries with spinel lithium titanate (Li4Ti5O12), methylene methanedisulfonate (MMDS) is evaluated as electrolyte additive. The linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) indicate that MMDS participates in the formation process of the solid electrolyte interface (SEI) film above 1 V, which is due to the interfacial reaction between the electrode and electrolyte: Li4Ti5O12 anodes are previously considered free from SEI films when cycled between 1 and 3 V. The stable SEI film around Li4Ti5O12 is seen most effective as a barrier layer in suppressing the interfacial reaction and resulting gassing from the Li4Ti5O12 surface. In addition, the results of electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and transmission electron microscopy (TEM) demonstrate that a thin and good conductive film can be formed on the Li4Ti5O12 surface ascribed to MMDS additive, which resulting the improvement of conductivity and a good ability of Li+ migration.

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