Materials details and cathode fabrication procedures, DFT calculation and AIMD simulation, UV-vis spectra of Li2S6 and 0.11 M BNC electrolyte, comparison of color change within different concentrations of BNC addition to the electrolyte contains different polysulfides, illustration of co-axial NMR tube and repeated Li NMR spectra, CV plots of three electrolytes, linear fitting of Randles-Sevcik plots for B1 and B2 peaks, voltage profile of in situ EIS, EIS and fitting results for each electrode at different DoD, Arrhenius plots and fitting results of baseline and 0.11 M BNC electrolyte, GITT plot of three electrolytes, illustration of operando Raman and operando XAS cell, Raman spectra of standard reference, normalized XAS spectra of standard reference, operando XAS spectra and MCR-ALS analysis results, XRF mapping and XANES comparison between washed and unwashed samples, XANES spectra on location #1, microscope images and XANES spectra of products from BNC with different polysulfides, summary of specific capacity and capacity retention between literature and this study.