Engineering On The Edge

A mug, transformed into a battery via five-layers of conductive paints. Image: Rice University

In the quest for better energy storage, researchers have investigated all manner of thin, flexible battery technology, power sources based on kinetic energy, and even batteries integrated into clothing. How about batteries you can paint onto any surface? According to research published in the June 28 issue of Scientific Reports, new “spray-on” battery technology could potentially turn any surface into an energy storage device.

The scientists from Rice University in Houston and Catholic University of Louvain in Belgium had to find a way to develop a paint version of each of the five layers of a lithium ion battery.They used lithium cobalt oxide as the cathode, Kynar Flex resin (with PMMA and silicon dioxide) as a separator, lithium titanium oxide and UFG as the anode, commercial copper paint as the negative current collector, and carbon nanotubes with carbon black particles dispersed in N-methylpyrrolidone for the positive current collector (because aluminum would not be safe to use in aerosol form).

“The hardest part was achieving mechanical stability, and the separator played a critical role,” said lead author Neelam Singh, a Rice graduate student. “We found that the nanotube and the cathode layers were sticking very well, but if the separator was not mechanically stable, they would peel off the substrate. Adding PMMA gave the right adhesion to the separator.”

The researchers successfully tested the paints on ceramic bathroom tiles, glass, flexible transparency film, stainless steel, and even the side of a beer stein.

The next step is to make the materials less reactive to air and moisture, particularly the electrolyte separator layer which can explode when it comes into contact with air. If they succeed, the potential for painted energy storage (even painted on solar cells for your house) could become a reality.

You can view a video about the technology below:

Source: Rice University