As of my last knowledge update in September 2021, flexible magnesium-ion batteries were still an area of active research and development, and there might not have been a well-established "typical" voltage rating. However, I can provide some general information on this topic up to that point.
Magnesium-ion batteries are being explored as an alternative to lithium-ion batteries due to the potential for higher energy density and lower cost. The voltage rating of a battery depends on the materials used for its electrodes and electrolytes. In traditional lithium-ion batteries, the voltage is typically around 3.7 to 4.2 volts, depending on the specific electrode materials.
For magnesium-ion batteries, the choice of electrode materials significantly influences the voltage. Research has shown that the voltage of magnesium-ion batteries can vary widely, but it's often lower than that of lithium-ion batteries. In many early experiments, magnesium-ion batteries demonstrated voltages in the range of 1 to 2 volts. The voltage could be affected by the choice of cathode and anode materials, as well as the electrolyte composition.
It's important to note that research in battery technology is rapidly evolving, and new developments might have occurred since my last update. To get the most accurate and up-to-date information on the voltage rating of flexible magnesium-ion batteries, I recommend checking recent scientific literature, research papers, and news articles in the field of battery technology.