The investigation of water vapor on the Li–O2 battery using a solid-state air cathode

A lithium (Li)–oxygen (O 2 ) battery based on an inorganic solid-state air cathode was fabricated, and the influence of water vapor (key component in the air) on the electrochemical behavior of the proposed Li–O 2 battery was deeply investigated. Excluding the negative influence of the corrosion of Li anode that existed in organic-based electrolyte Li–O 2 battery when operated in wet environment, our results showed that water vapor has a positive effect on the discharge and cycling performances of the Li–O 2 battery using a solid-state air cathode. The discharge capacity reached 11734 mA h g −1 (7.8 mA h cm −2 ) in wet O 2 , which was not markedly different with that in dry O 2 (11956 mA h g −1 (8.0 mA h cm −2 )). However, the discharge voltage in wet O 2 was about 110 mV higher than that in dry O 2 . Although the formation of LiOH increased the charge overpotential, the formed LiOH in turn minimized the decomposition of carbon to form Li 2 CO 3 , and enhanced the cycling performance to a certain extent. In addition, we showed that the polarization involved by water vapor could also be largely decreased by slightly increasing the operating temperature; the charge voltage plateau decreased from 4.04 to 3.3 V when the temperature increased from 25 to 50 °C. These results suggest that the Li–O 2 battery using a solid-state air cathode is promising for practical application, especially in wet environment.