fig2

Figure 2. (A) Contact angle test on NbN/C-modified PP (bottom) and pristine PP (upper). (B) Folding test to prove the strong adhesion of the modifying layer to PP. SEM images of (C) pristine PP separator and NbN/C@PP from (D) top view and (E) cross-section view. (F) Digital images of adsorption test in Li₂S₄ solutions before and after adding carbon black and NbN/C. (G) Adsorption energy calculation of Li₂S₄ on the surfaces of C (upper) and NbN (200) (bottom). (H) “Shuttle effect” test by using an H-type container with different separators: NbN/C@PP (bottom) and pristine PP (upper).