Revealing competitive interfacial reactions in high-energy Li–S batteries

a, Detailed local CV profiles highlighting the initial reduction peaks associated with the conversion from Li 2 S 6 to Li 2 S. b, Comparison of CV profiles in symmetric cells (0.2 M Li 2 S 6 ) with and without Ru NCs/HPCS and CV profile of a blank electrolyte lacking Li 2 S 6 species. ΔE p and i pc denote peak potential difference and cathodic peak current, respectively. c, Potentiostatic discharge profiles for Li 2 S deposition at 2.05 V across increasing Li 2 S 6 electrolyte concentrations from 0.2 M to 1.0 M. d, Nyquist profiles from EIS conducted before potentiostatic discharge at OCV with Li 2 S 6 electrolyte concentrations from 0.2 M to 1.0 M. e, Schematic illustration showing the relationship between electrode kinetics and varying charge transfer/diffusion/conduction at increasing Li 2 S 6 concentrations (0.2–0.8 M). f, Nyquist profiles from EIS conducted after potentiostatic discharge with Li 2 S 6 electrolyte concentrations ranging from 0.2 M to 1.0 M. g, Nyquist profiles from EIS before potentiostatic deposition, detailing resistance components including contact (R ohm ), charge transfer (R ct ) and diffusion (W). Inset is the equivalent circuits used for fitting before potentiostatic deposition. h, Nyquist profiles from EIS after potentiostatic deposition, illustrating the emergence of a new interfacial resistance (R interface ) owing to Li 2 S deposits. Inset is the equivalent circuits used for fitting after potentiostatic deposition. i, A comprehensive summary of resistance changes before and after Li 2 S potentiostatic deposition at different Li 2 S 6 concentrations. j, Analysis of reaction kinetics including peak current, potential gap and integrated capacity from symmetric cells shown in Fig. 5a, along with a correlation of electrode parameters calculated on the basis of the loading of sulfur-free active materials (Ru NCs/HPCS) and various Li 2 S 6 concentrations.