New research could help create nuclear batteries that have controllable energy release like conventional batteries but with many times the storage capacity.
Scientists at Surrey University have identified a material that may have the necessary properties to trap energy in its atoms and then release it when required, unlike existing nuclear batteries that release energy at a constant rate.
Nuclear batteries typically harness energy from naturally decaying atoms. This stored energy is much greater than that in electrochemical batteries and is used for applications that require long, continuous energy supplies, such as medical implants or spacecraft.
The Surrey researchers, led by Prof Phil Walker, have gathered evidence about the 212 isotope ofl bismuth that suggests it has the necessary atomic structure to allow energy to be released on demand without needing large amounts of additional energy to start the process.
‘The idea is to find an example where there’s just a small energy barrier to release that stored energy,’ Walker told The Engineer.
‘It’s like having a reservoir half way up a hill. You pump the water up the hill and it gets stored there. It doesn’t take much to push the water over the lip of the reservoir.’
The team trapped energy in the nuclei of bismuth-212 ions using a particle accelerator to put them into an excited state, and then observed them by capturing the particles in a storage ring.
The measurements they collected suggested the nuclei also had a slightly higher energy state that would provide the mechanism for the energy to be released more easily.
‘We found that the reported properties were not right,’ said Walker. ‘And now we’ve measured them properly it suggests there should be a nearby state through which we can de-excite it.’
The next step will be to develop and carry out experiments to prove the bismuth-212 can be de-excited in this way.
Unfortunately, the GSI accelerator in Darmstadt, Germany, where the Surrey team were carrying out their experiments is now undergoing refurbishment and Walker is looking for alternative locations to continue the work.
He added that previous experiments that claimed to have found a material with a suitable intermediate energy state have not been reproducible.
The creation of a working controllable nuclear battery is still a long way off but if a suitable material can be found in which to store energy then it may be possible to use a mechanism such as a laser to release the energy at will – although it would also still be released through natural nuclear decay.