Fig. 9.

Electrochemical performance of Li–S batteries with the GZCNT-coated Li foil anode. a–c Charge–discharge properties at 0.2 C (0.6 mA cm^–2) with a capacity of up to 3 mAh cm^–2. Discharge capacity and Coulombic efficiency of Li-S batteries with a a pristine Li foil and b the GZCNT-coated Li foil anode, and c charge and discharge curves of pristine and after-200-cycle Li–S coin cells. d Electrochemical impedance spectra of pristine and after-200-cycle Li–S coin cells assembled from blank and GZCNT-coated Li. Frequency: 0.1 Hz–1 MHz, perturbation amplitude: 5 mV, measured at 100% SOC. e, f Top-view SEM images of the blank (e) and GZCNT-coated Li foils (f) from Li–S coin cells after 200 cycles. The insets show the digital photos of the corresponding Li anodes without (e) and with (f) GZCNT interfacial layers after 200 cycles. Scale bar, 5 μm for e and 1 μm for f