Researchers use MRI to crack battery testing

A group of scientists has worked out a way of testing if a battery is going to go wrong without having to open it.

Researchers at Cambridge University, Stony Brook University, and New York University have developed a methodology based on magnetic resonance imaging (MRI).

According to the popular science magazine Nature Materials, which we get for its substrate centrefold, the technque creates the possibility of improving battery performance and safety by serving as a diagnostic of its internal workings.

MRI is normally used for looking at people’s brains and growths in the body, but it is not used where there is too much metal. This is because conducting surfaces effectively block the radio frequency fields that are used in MRI to see beneath surfaces.

But the researchers worked out a way of turning this to their advantage. One of them thought, if radio frequency fields do not penetrate metals, you can use them to perform very sensitive measurements on the surfaces of the conductors.

With a lithium-ion battery you can directly visualize the build-up of lithium metal deposits on the electrodes after charging the battery.

These can detach from the surface, eventually leading to overheating, battery failure, and catch fire or explode.

By seeing the small changes on the surface of the battery electrodes, the researchers could test many different battery designs and materials under normal operating conditions.

Alexej Jerschow, a professor in the Department of Chemistry at New York University who was behind the research, said that as electrode and electrolyte materials are being developed the non-invasive MRI technology could potentially provide insights into the microscopic processes inside batteries.

This will hold the key to making batteries lighter, safer, and more versatile, Jerschow says.

Using MRI, Jerschow said that he could identify where the chemical species inside the battery are located without having to take the battery apart.

At the moment, the resolution is not quite good enough for commercial use and the team want to get it to work on much larger batteries. But so far the data gathered from the measurements is “unprecedented”.