It's not just the power source you have a problem with, it's the whole device. There is no hard and fast data to prove that any electronics will actually last that long. At the very least you'd need some kind of hermetically sealed container to have a good chance of working preservation, IF you had confidence in a reliable power source.
The chances are that one of the crucial link components will fail way before that 100 year period is up.
Without some form of regular check and maintenance, I'm doubtful you'd get anywhere near the longevity you require.