As of my last knowledge update in September 2021, there isn't a fixed or "typical" voltage rating for flexible lithium-air (Li-Air) batteries, as the development of Li-Air batteries is still an ongoing research area. The voltage of a Li-Air battery depends on various factors, including the materials used, the design of the battery, and the specific configuration.
Traditional lithium-ion batteries typically have a voltage of around 3.7 to 3.8 volts per cell. Li-Air batteries have the potential to provide much higher energy densities than traditional lithium-ion batteries due to the use of oxygen from the air as one of the reactants. This could potentially result in higher voltages, but there are significant technical challenges in developing practical and reliable Li-Air batteries, including issues related to stability, efficiency, and safety.
It's important to note that the field of battery research is rapidly evolving, and new developments may have occurred since my last update. I recommend checking the latest scientific literature or reputable sources in the field for the most up-to-date information on the voltage ratings of flexible Li-Air batteries.