Fig. 4. Discharge performance and characterization of discharge products.

a First discharge curves with 0.6% commercial Pt/C and N-HP-Co SACs at a current density of 100 mA g⁻¹ with a limiting specific capacity of 3000 mAh g⁻¹. b CV curves. c Full range rate performances of Li–O₂ batteries at different current densities. d, e FESEM images of the discharged cathodes with (d), 0.6% commercial Pt/C and (e) N-HP-Co SACs at a current density of 100 mA g⁻¹ with a limiting specific capacity of 3000 mAh g⁻¹, 500 nm in (d, e); f The corresponding XRD patterns. The standard spectra for Li₂O₂ are also shown for reference. Discharge mechanism of 0.6% commercial Pt/C (g) and N-HP Co SACs (h) in the Li–O₂ batteries.