As of my last knowledge update in September 2021, there were no commercial flexible lithium-air (Li-Air) batteries available on the market. Lithium-air batteries are still primarily in the experimental and research stages due to numerous technical challenges that need to be overcome before they can be commercialized. Therefore, I don't have specific information on the voltage rating of a typical flexible Li-Air battery because they were not widely available or well-documented at that time.
It's important to note that battery technologies and research can evolve rapidly, so there might have been developments or breakthroughs since then. I recommend checking recent scientific literature, research articles, or manufacturer announcements for the latest information on flexible lithium-air battery technology and its voltage ratings.