THE EFFECT OF SOLID ELECTROLYTE INTERPHASE ON THE MECHANISM OF OPERATION OF LITHIUM-SULFUR BATTERIES

The controlled formation of SEI type surface films on composite S-C electrodes is responsible for the realization of quasi-solid-state mechanism of the electrochemical reaction of Li ions with sulfur encapsulated in microporous carbons. The formation of SEI type surface films during the initial cycles is governed by the electrolyte solution composition, the discharge cut off voltage and microporous structure of carbon host. SEI formation was observed in FSI-based IL and organic carbonate-based electrolyte solutions as a result of the reaction of Li polysulfides with FSI-anions or organic carbonate molecules during the initial discharge. FEC-based electrolyte solution demonstrates improved capacity retention during charge–discharge cycling of S/C composite electrodes compared to the EC-based electrolyte.