Donut, Anyone? Batteries Are Coming in All Shapes and Sizes

Christine Ho made a donut-shaped battery — but she had a good reason. The founder of California-based startup Imprint Energy wanted to prove that her chemistry could be used to make batteries in any shape a customer might ask for. It’s just one of the ways Imprint has emphasized versatility as critical to the future of the battery business.

Today, the batteries powering most of our electronic devices and electric cars rely on lithium-ion chemistry. While it’s well suited to pack in a lot of energy in a small space, that chemistry also comes with two downsides: Lithium-ion batteries are still quite expensive and, if not used properly, they can catch fire. Ho, who began her career in batteries as an undergrad at the University of California, Berkeley, realized there was room for alternate chemistries in emerging applications, especially small internet-connected devices often called the “internet of things.”

You can listen to a conversation with Ho on the Zero podcast below, and read a transcript of the episode here. To stay on top of new episodes, subscribe to Zero on Apple Podcasts, Spotify and Google.

One such application, quickly gaining popularity, is the use of “smart labels” that can be stuck on packages or delivery boxes, and contain a small battery and a transponder to help track the package remotely. Smart labels offer three advantages. Customers are happier knowing where their goods are. Companies, especially those in pharma and food, save money by better managing the delivery process and cutting down on fuel use and waste, which can account for as much as 40% of total production. And the planet benefits from fewer planet-warming emissions.

To find a battery solution that would work for such applications, Ho began with the disposable AA or AAA battery, which uses zinc and manganese chemistry. These batteries come in rigid cells because they are filled with toxic liquid that could leak out if not sealed tightly in a metal container. The liquid, called an electrolyte, is necessary to enable the chemical reaction that generates electricity.

The alternative was to develop a solid electrolyte, and that invention became the basis of creating Imprint Energy in 2010. Eliminating the need for a liquid also made new shapes and sizes of battery possible. “They’re flexible,” Ho said while bending a battery during a tour of Imprint’s Alameda-based factory. “There’s just infinite demand for better batteries that are safer and have higher performance.”

Over the past decade, Imprint has been perfecting its chemistry and lean manufacturing process. The factory floor in Alameda is no bigger than your average classroom, and that’s because, as the name of the startup suggests, the batteries are 3D-printed (or, technically, screen-printed using stencils). The process is only a little more complicated than seeing a piece of blank paper emerging with letters printed on it.

Imprint’s batteries are being trialed by Sensos, a Sony company that makes smart labels to track pharmaceuticals and crop seeds. That label uses a cellphone connection. Another trial is with Renesas, which uses bluetooth sensors to track food deliveries from farm to retailer. So far the startup has raised $25 million from investors including Phoenix Venture Partners and Global Value Investment Portfolio.

Imprint’s smart labels currently cost between $5 and $10 per unit depending on whether you use bluetooth or cell connections. At commercial scale, Ho says each should cost between $0.25 and $5, which would make them appealing for tracking the transport of both cheap and expensive goods.

Though Ho is looking to raise more money, she says Imprint won’t be building its own battery factories. That’s because larger manufacturers already have the equipment to print batteries; all Imprint needs to do is ship over the materials and those manufacturers will finish the job. One manufacturer each in Mexico and China is already making Imprint batteries.

But that doesn’t mean it’s been easy. “It’s been more than 10 years,” says Ho of the period since founding Imprint. “Every day was a hard day. But scaling up is really hard.”