Identification of lithium-sulfur battery discharge products through ⁶Li and ³³S solid-state MAS and ⁷Li solution NMR spectroscopy

⁶Li and ³³S solid-state magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy was used to identify the discharge products in lithium-sulfur (Li-S) battery cathodes. Cathodes were stopped at different potentials throughout battery discharge and measured ex-situ to obtain chemical shifts and T₂ relaxation rates of the products formed. The chemical shifts in the spectra of both ⁶Li and ³³S NMR demonstrate that long-chain, soluble lithium polysulfide species formed at the beginning of discharge are indistinguishable from each other (similar chemical shifts), while short-chain, insoluble polysulfide species that form at the end of discharge (presumably Li₂S₂ and Li₂S) have a different chemical shift, thus distinguishing them from the soluble long-chain products. T₂ relaxation measurements of discharged cathodes were also performed which resulted in two groupings of T₂ rates that follow a trend and support the previous conclusions that long-chain polysulfide species are converted to shorter chain species during discharge. Through the complementary techniques of 1-D ⁶Li and ³³S solid-state MAS NMR spectroscopy, solution ⁷Li and ¹H NMR spectroscopy, and T₂ relaxation rate measurements, structural information about the discharge products of Li-S batteries is obtained.