Online cell pressure tracking analysis and sulfur species depositing/stripping behavior study of lithium sulfur batteries

•Online cell pressure tracking analysis is used to study gassing effect in Li-S cell.•Gassing effect of ether-based electrolyte in Li-S cell is negligible.•Sulfur tends to deposit on the top surface of thick cathode.•Volume effect caused by the dissolution of sulfur species is notable.•The unexpected deposit behaviors and volume effect are responsible to cell failure. Cell failure is easy occurring in Li-S cell. Electrolyte consumption caused by side-reactions between electrolyte and anode is one of the reasons for the cell failure, but the underlying mechanism for the cell failure is still not clear. To get insight into the electrolyte decomposition, in this work, online cell pressure tracking analysis (OCPTA) is applied to study the gassing effect caused by electrolyte decomposition reactions during charge–discharge processes and the study on depositing/stripping behavior of sulfur species performed. It is found that gassing effect is negligible in the cell with conventional ether-based electrolyte when electrolyte decomposing, but volume effect caused by sulfur species dissolution is notable. Together with the sulfur preferentially depositing on the top surface of cathode, it leads to electrolyte insufficiency on the top surface of electrodes, enhancing the risk of cell failure.