A thin sheet of materials wrapped around the battery in your cell phone could squeeze out enough extra energy to enable you to use your phone for a lot longer than usual. That’s the latest wonder product from a startup called the Paper Battery Company, which has been working on the technology for the past six years and has just started to get its sheets into the hands of phone and gadget makers for testing.
Each of Paper Battery Company’s sheets is actually an ultra-thin ultracapacitor, which is an energy storage device like a battery, but which stores energy in an electric field (instead of through a chemical reaction the way a battery does). Ultracapacitors are great devices if you want to deliver a lightning-quick surge of power, and they can survive hundreds of thousands more charge and discharge cycles than a battery can.
The downside of ultracapacitors, though, is that they store a lot less energy than batteries — commonly as little as 5 percent of the energy of comparable lithium-ion batteries. That’s why for many years now, researchers and companies have been pairing ultracapacitors with batteries as a way to make batteries last longer.
Ultracapacitors are already being used commercially today in applications like electric vehicles, wind turbines, cell phone base stations and stop-start engine systems for cars. They are commonly made up of two metal plates, coated with a sponge-like, porous material known as activated carbon and immersed in an electrolyte made of positive and negative ions dissolved in a solvent. During charging, ions from the electrolyte accumulate on the surface of the carbon-coated plates.
Paired with batteries, ultracapacitors can take on some of the more intense charging needs, leaving the battery to deliver the slow and steady stuff. Dave Rich, head of new technologies and applications at Paper Battery Company, uses a metaphor of an exercise machine to explain how it works: When you’re biking or running at a moderate pace for a long time, that’s a good fit for the battery, but when you hit the peaks and valleys on the exercise program, the ultracapacitor kicks in.
Paper Battery Company’s ultracapacitor sheets use commercially available materials, so their innovation (right now) isn’t so much about a materials breakthrough. Instead, the company has innovated around the manufacturing (printing with custom ink), the processing of the materials and the packaging and architecture of the device, enabling it to deliver one of the thinnest ultracapacitors out there. It’s 0.4 mm across, about as wide as 4 sheets of paper stacked together.
“The benefits of pairing supercapacitors with batteries is well known, but before this they’d always been too expensive, too big and too complex. This is the first time there’s a solution with this thin form factor,” says Rich.
Why is thinness so important? Because companies designing and making cell phones, gadgets and even the latest wearable devices are obsessed with making computing devices smaller, lighter and thinner. Many ultracapacitors would be far too big and heavy to reasonably be able to fit into a sleek iPhone or the latest fitness tracker without adding cost and weight. Electric car makers are also interested in reducing weight and extending battery range, and one day this type of tech could be used in cars like Tesla’s (Tesla CEO Elon Musk has expressed love for the ultracap before).
Some researchers in labs are working on similar types of super light weight ultracapacitors. Scientists at Nanyang Technological University (NTU) in Singapore, Tsinghua University in China and Case Western Reserve University in the U.S. recently demonstrated a fiber-like ultracapacitor that could one day be woven into clothing.
But demonstrating tech in the lab and building a commercial company are different things entirely. Paper Battery Company, based in Troy, New York, originally looked at research from Rensselaer Polytechnic Institute around an ultra-thin battery which was made mostly (90 percent) out of cellulose, the same plant-derived material used to make paper. Paper Battery Company CEO Shreefal Mehta explained to me that the company soon realized that technology wasn’t going to deliver the characteristics it needed, so it rebooted and changed courses. The name stuck, though.
Now Paper Battery Company has moved past the R&D phase, and it’s currently moving toward commercializing the product. It’s already shipping prototypes to customers for testing and has a big partnership deal with battery heavyweight TWS. Mehta tells me that by the second quarter of next year, the company expects to start bringing in revenue.
Paper Battery Company also recently closed on some new funding, a $3 million Series A round. Investors Caerus Ventures, Tylt Lab and longtime materials and energy investor Tom Baruch (the founder of CMEA Capital) participated in the deal. Mehta says the company has raised a total of $5 million — a surprisingly low figure for a battery company — to date, but it plans to raise more in another round down the road.
Paper Battery Company’s battery-boosting ultracap sheets are just the first product the team plans to commercialize. It’s still a pretty young company. They’ve got just 12 employees. Down the road its technology could be used to accomplish other power features, and could be used without batteries, too. Medical devices and other computing hardware with low power needs could operate on a stand alone ultra-thin ultracap.
But the startup is at a crucial point in its life — time to bring in customers and make some money. And if it succeeds, it would show how a lean energy storage startup can operate without building a big factory and without spending a lot of money to get there.