Futurology

I like your thinking but I doubt it will work in its current state.

The researchers then implanted the battery under the skin on the backs of rats and measured its electricity output. Two weeks later, they found that the battery can produce stable voltages between 1.3 V and 1.4 V, with a maximum power density of 2.6 µW/cm2. Although the output is insufficient to power medical devices, the design shows that harnessing oxygen in the body for energy is possible.