Fig. 5. (a) EIS of K–Se and K–S batteries after three cycles at 0.1C in 5 M electrolyte. (b) Rate capability and (c) long-term cyclability. SEM images of (d and e) Se and (f and g) S cathodes at charging state (3.0 V) after 350 and 100 cycles at 0.5C, respectively. The solution in the vials (insets in (d) and (f)) are obtained by immersing the cycled Se and S cathodes in DEGDME for 10 min. The EDS mapping (inset in f) corresponds to the region marked by the red frame in (f). (h and i) Schematics illustrate the deposition behaviors of Se and S. (j and k) The total density of states (DOS) and calculated band gaps of KnSe and KnS.
