HOUSTON First came cheese in a can. Then tans.

Now, batteries?

It sounds crazy, but engineers at Rice University say they've created a battery that can be spray-painted onto virtually any surface.

The innovation comes as Apple and other technology designers seek sleeker and ever-more powerful batteries for laptops and devices. They've been pushing engineers to create unconventional, more space-efficient batteries.

And that's what Rice engineer Pulickel Ajayan did last year when he asked a few of his graduate students, including Neelam Singh, to begin experimenting with spray-on batteries.

Singh admits she was a bit skeptical when Ajayan first made the suggestion.

"I thought it was a very interesting idea to see if we could make a battery on any surface — I thought it was crazy also," she said. "But it was worth trying."

Good thing she tried, because after much tinkering, the concept worked and now it could become a key part of powering new technologies.

"This means traditional packaging for batteries has given way to a much more flexible approach that allows all kinds of new design and integration possibilities for storage devices," Ajayan said.

The results of the experiments were published Thursday in Nature's online, open-access journal, Scientific Reports.

A traditional lithium-ion rechargeable battery contains a spiral of thin sheets of positive and negative electrodes through which ions flow during charging and discharging.

The new battery also has layers, but they are flat rather than coiled, and applied in a manner similar to the way in which primer, paint and weather coating are added to a painted surface.

Significant hurdles remain before the technology can be brought from the lab to a commercial scale.

Some of the materials Singh and her colleagues worked with are to some extent toxic, but she's confident that environmentally friendly alternatives can be found. She also said the battery's efficiency can be improved.

In addition to powering mobile technologies, Singh believes the spray-on batteries could play an important role in making solar power more practical. They could be added to home-building materials to store energy collected by solar panels during the day, which could be then used at nighttime.