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

Abstract

A lithium (Li)–oxygen (O2) 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–O2 battery was deeply investigated. Excluding the negative influence of the corrosion of Li anode that existed in organic-based electrolyte Li–O2 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–O2 battery using a solid-state air cathode. The discharge capacity reached 11734 mA h g−1 (7.8 mA h cm−2) in wet O2, which was not markedly different with that in dry O2 (11956 mA h g−1 (8.0 mA h cm−2)). However, the discharge voltage in wet O2 was about 110 mV higher than that in dry O2. Although the formation of LiOH increased the charge overpotential, the formed LiOH in turn minimized the decomposition of carbon to form Li2CO3, 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–O2 battery using a solid-state air cathode is promising for practical application, especially in wet environment.