Spray-On Battery Could Slip Power Into Tighter Spaces

Tuesday, July 3, 2012

Spray-On Battery Could Slip Power Into Tighter Spaces

By Rachelle Dragani
TechNewsWorld
06/29/12 5:00 AM PT

Designers of mobile devices often have to work around bulky lithium-ion batteries, some of which take up the lion's share of space inside a given gadget. Researchers at Rice University, though, have developed a battery that can be painted onto a surface. The technology still requires more development before it's commercially viable, but if it's sufficiently improved it could also be used in applications like solar cells.

Researchers at Rice University have developed a paint that works as a battery, and it could change the way batteries are produced and reduce energy storage restrictions.

The paint-on battery is similar in material balance to traditional lithium-ion batteries. It has five layers -- a positive and a negative current collector, a cathode, an anode and an ion-conducting separator in the middle.

But unlike typical lithium batteries, a perfected paint-on version wouldn't carry the same restrictions in design that traditional batteries do. Each layer is sprayed on rather than pieced together.

As consumer electronic products such as smartphones and tablets get smaller and thinner, engineers struggle to fit a long-lasting, traditional battery into tighter spaces. A painted battery could alleviate those design restrictions.

Additionally, as scientists explore alternative forms of energy and look to add batteries to new technologies such as solar panels or textiles, a versatile, spray-on battery has the potential to eliminate further design frustrations.

"Paintable batteries have the capability of direct and seamless integration with objects," Neelam Singh, lead author on the study, told TechNewsWorld.

Researchers tested the paint layers on ceramics, glass and stainless steel on a variety of shaped surfaces to see how they would react to the different structures.

The results of the study were published Thursday in Nature Scientific Reports.

The research is a step forward for scientists and engineers working to consolidate batteries and explore ways to cut down on storage restrictions, said Yan Wang, assistant professor of mechanical engineering at the Worcester Polytechnic Institute. He called the work a "significant development" in battery manufacturing but added the team still has work ahead of it before it can revolutionize the industry.

"The drawbacks include the cycle life and rate performance," he told TechNewsWorld. "The performance needs to be as good as the state-of-the-art of lithium-ion batteries. The paper has only about 60 cycles, which is still too short for real applications."

The current product is also limited in scope because it cannot be handled by non-professionals and still can't stand all outside elements.

"To be able to make batteries at home we need to develop materials that are safer, non-toxic and do not degrade in the presence of air or moisture," said Singh.

The team has acknowledged those drawbacks and is already working on the next step to making the spray-on battery a viable product, said Singh.

"We have demonstrated the concept of paintable batteries, and the next step is to develop new materials for the battery that are not air- or moisture-sensitive, [and are] non-toxic and safe to handle by non-experts," said Singh. "We are also working on developing paints for packaging the battery and making every layer, including packaging, by spray-painting technique."

If the researchers can improve the life of the spray-on battery, Wang said, it could still be several years before a product hits the market. But if it does, the practical applications could be widespread across industries that are experimenting with battery power, the biggest possibility being with solar power, said Singh. Since solar panels require large surface areas, the design could be ideal.

"Our current work is the demonstration of the paintable battery concept, but it opens up immense possibilities of integration with energy capture devices such as solar cells, as well as objects of daily use," she said. "We think that it can be used with printed electronics, RFID or other smart objects."