Fig. 6: Suppressed Li metal corrosion against PSs and LiF-enriched SEI formation with the Ca electrolyte.

a Coordination number profiles for Li⁺−S (the sulfur atom in S₄²⁻) and Li⁺−O (the oxygen atom in FSI⁻ anion) for the control and Ca electrolytes, assuming complete dissolution of sulfur into electrolyte at E/S ratio of 5 μL mg⁻¹. b Scheme of the Li⁺ solvate for the control and Ca electrolytes. c ToF–SIMS three-dimensional render images of the LMAs (represented by Li₂⁻) in the coin cells (E/S = 4 μL mg⁻¹) with the control and Ca electrolytes. d Cryo-TEM images of the LMAs in the 0.2 M Li₂S₈ containing-control electrolyte (left) and the 0.2 M Li₂S₈ containing-Ca electrolyte (right). The scale bars are 300 nm. e LSV of the Li-Ni half cells with the 0.2 M Li₂S₈-containing control and Ca electrolytes under cathodic scan at 0.5 mV s⁻¹. f Plot of the CE at the second cycle for the Li-Ni half cells with the 1.6 M Li₂S₄ (corresponding to E/S = 5 μL mg⁻¹) containing the control and Ca electrolytes as a function of calendar ageing time. The data are presented as mean values ± standard deviation. Error bars denote the standard deviation from the measurements for each cathode.