Understanding the Role of Prop-1-ene-1,3-Sultone and Vinylene Carbonate in LiNi1/3Mn1/3Co1/3O2/Graphite Pouch Cells: Electrochemical, GC-MS and XPS Analysis

The role of prop-1-ene-1,3-sultone (PES) used alone or in combination with vinylene carbonate (VC) in LiNi1/3Mn1/3Co1/3O2(NMC)/graphite pouch cells was studied by correlating data from differential capacity (dQ/dV) analysis, gas chromatography/mass spectroscopy (GC−MS), ultrahigh precision coulometry, storage experiments and X-ray photoelectron spectroscopy. VC formed more stable and protective SEI films at both graphite and NMC surfaces due to the formation of a polymer of VC. For PES-containing electrolytes, the preferential reaction of PES led to the formation of SEI films with higher oxygen content at both graphite and NMC surfaces due to the additional oxygen contribution of sulfite species and substantially less LiF compared to control and VC electrolytes. PES also led to thicker SEI films at the NMC surface. When VC was combined with PES, features of the SEI films from both VC and PES were observed. The SEI film features for VC and PES used alone or in combination can explain the improved electrochemical performance as well as the lower production of gas observed with these additives compared to control electrolyte.