ESM provides nanoscale perspective of li-ion batteries

A research team led by ORNL’s Nina Balke, Stephen Jesse and Sergei Kalinin has developed a new type of scanning probe microscopy called electrochemical strain microscopy (ESM) to examine the movement of lithium ions through a battery’s cathode material.

‘We can provide a detailed picture of ionic motion in nanometre volumes, which exceeds state-of-the-art electrochemical techniques by six to seven orders of magnitude,’ Kalinin said.

Researchers achieved the results by applying voltage with an ESM probe to the surface of the battery’s layered cathode. By measuring the corresponding electrochemical strain, or volume change, the team was able to visualise how lithium ions flowed through the material.

Conventional electrochemical techniques, which analyse electric current instead of strain, do not work on a nanoscale level because the electrochemical currents are too small to measure, Kalinin explained.

‘These are the first measurements, to our knowledge, of lithium-ion flow at this spatial resolution,’ Kalinin said.

Lithium-ion batteries, which power electronic devices from mobile phones to electric cars, are valued for their low weight, high energy density and recharging ability. Researchers hope to extend the batteries’ performance by lending engineers a finely tuned knowledge of battery components and dynamics.