RADIOACTIVE BATTERIES

''Minuscule amounts of radioactive elements could safely power handheld electrical devices for months or even years, according to new research from the University of Missouri.
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Whatever the material, radioactive batteries would be ideal for small devices like environmental sensors placed in remote or difficult regions to reach, or as the power source for electronic implants that could last the lifetime of a patient, eliminating the need for repeat surgeries.
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Disposing of a radioactive battery also raises some concerns. Although he half life of sulfur 35 is only 87 days, as opposed to the more than 700 million-year half-life of some uranium isotopes, scientists wouldn't want even mildly radioactive material like sulfur 35 to leak into the environment where it could cause harmful mutations in animals or cancer in humans.

However, Kwon is quick to downplay such concerns. Kwon notes that current AA and AAA battery need a special disposal system. A similar system could be developed for radioactive batteries as well.'' [source]