August 28, 2019: A group of scientists from Spain, Australia, Sweden, Germany, Switzerland and Turkey have used operando neutron radiography on lead acid battery function for the first time. In the study, due to be published in the Journal of Power Sources on October 31, the scientists, who come from a range of institutions including the University of New South Wales in Australia and the University of the Country of Basque in Spain, say that although the technique has been used on lithium batteries, their research is the first to apply neutron imaging techniques to understand the working processes of lead acid batteries.
“This work highlights the potential of neutron imaging for tracking battery function and outlines opportunities for further development,” the report – Monitoring Lead-acid Battery Function Using Operando Neutron Radiography – says.
Several other techniques can monitor batteries in situ, however they can be intrusive, for instance inserting sensors into the battery cell, which can result in the cell changing its behaviour, the scientists say.
While they acknowledge four non-intrusive techniques – ultrasound, holographic laser interferometry, magnetic field measurements and synchrotron X-ray radiography and tomography, the latter which BESB has covered before, see here – there are differences with their technique, they say.
“One of the most important differences between neutrons and X-ray radiation (synchrotron) is that neutrons collect information of the nucleus of the atoms, and X-ray radiation of the electronic shell of the atoms,” said researcher Joxemi Campillo Robles, in the Applied Physics department at the University of the Basque Country.
“The main advantage of neutrons with respect to X-ray radiation is their greater penetration depth. High energy X-rays can penetrate only 1-2mm in lead, and while it seems to be a very promising technique, it is limited to analyzing thin lead acid battery plates. Instead, neutrons can pass easily through lead, and obtain information from the inner region of the plates.”
The researchers made new casings with materials better suited for allowing the neutrons to be transmitted, and the resulting imaging data clearly imaged electrodes, separators, electrolyte and case components, even picking up manufacturing faults.
“We observed the evolution of gas in the electrolyte/electrode surface as well,” the study said.
Robles said the next study would look at how the electrochemical processes in electrodes can be correlated with changes seen in neutron transmittance.
“We have also performed neutron tomography measurements to check the evolution of the inner structure of the battery,” he said.
The report says that while the basic principles of lead acid battery operation have not changed, ‘its recyclability and innovations in the cell construction have kept the technology pertinent and enhanced its usefulness for new applications’.