Fig. 3

Electrochemical performances with fixed capacities. a, b The discharge–charge profiles of a Li–O₂ battery with a carbon paper electrodes and b carbon nanotube (CNT) electrodes. The current densities were 0.1 mA cm⁻², and the cutoff voltage was 2.3 V/4.6 V. c–f In situ differential electrochemical mass spectrometry (DEMS) analysis of the gas consumption and evolution during Li–O₂ cell operation: c, e discharge to 0.25 mAh cm⁻² at current density of 0.25 mA cm⁻², and d, f charge to 0.25 mAh cm⁻² at current density of 0.125 mA cm⁻². The error of the DEMS data obtained during discharge is 5%, and during charge is 3%