fig21

Figure 21. (A) Schematic illustration of the synthesis process of freestanding layer-structure Se cathode; (B) Cross-sectional SEM image of freestanding layer-structure Se cathode. The inset of (B) is a digital photo of a freestanding layer-structure Se cathode; (C) Digital images of different Se cathodes before/after 30 cycles; (D) Cycling performance of various Se cathodes under the current density of 50 mA g^-1; (E) RQH/RQL analyses of various Se cathodes; (F) Rate performance of freestanding layer-structure Se cathodes with different Se loadings; (G) Areal capacity comparison of various Se cathodes^[140]. Copyright 2018, Elsevier.