The thermal reactions of lithiated and delithiated sulfur cathodes with 1.3M lithium bis(trifluoromethane sulfonyl)imide (LiTESI) in tetra(ethylene glycol)dimethyl ether (TEGDME) are investigated by differential scanning calorimetry (DSC). To understand the thermal reactions of cycled sulfur cathodes, the products formed during cycling are characterized by ex-situ X-ray photoelectron spectroscopy (XPS).