Fig. 1.

Operando X-ray microscopy and diffraction for Li-S batteries during the initial discharge. (a) Combined schematic illustration of the experimental set-ups for X-ray microscopy and diffraction. (b) Voltage profile, (c) operando X-ray diffraction pattern and (d) normalized intensity of α-S₈ and Li₂S of the sulfur electrode at a rate of 0.1 C (1C = 1672 mAh g⁻¹) during discharge. Yellow and red circles in (d) indicate normalized X-ray diffraction intensities of α-S₈ (222) and Li₂S (111), respectively. The sky blue squares are the normalized amount of all sulfur clusters calculated based on the total integrated signal from X-ray microscopy. (e) Operando X-ray microscopy images of a sulfur electrode at different depths of discharge (DODs) indicated as a %. (f) Enlarged image of a single sulfur cluster in the region indicated by a red arrow at 0% DOD (top) and area changes of the same cluster at different DODs (bottom). (g) Computed equilibrium fraction of total sulfur for a given sulfur species, with varying lithium concentration, from statistical mechanics calculations using DFT energies of solvated sulfur species.