If lithium ion batteries have revolutionized the consumer electronics market with their high-power, low-weight features, zinc could be set to revolutionize the “wearable” electronics market.
Firstly, why would lithium ion not meet this demand? Indeed, the Nike Fuelband worn on the wrist does just that, but because of lithium’s reactivity with air and water it has to be encased in a protective shell, making it rigid and more bulky than it needs to be.
As a Bloomberg article on the topic explains, the only part of the band that is not flexible is the rigid battery section. This drawback of lithium ion combined with its toxicity will likely remain a barrier to the metal’s adoption in a host of potentially exciting electronic developments requiring flexibility, miniaturization and low risk of toxicity if worn close or even under the skin.
Enter technology pioneers in California.
Groundbreaking work is being done by a startup called Imprint Energy. Still in its early stages, the firm is using screen printing technology to produce small batches – just 100 a day – of batteries so thin they could potentially be just a few hundred microns thick.
Not only are the batteries thin, but also remarkably flexible, opening up the possibility that they could be worn or incorporated into devices that are irregular shapes.
So why hasn’t zinc been used before?
Well, it was in the early days of battery production, but its tendency to form dendrites – tiny fibers that grow in a liquid electrolyte – get in the way of the charging reaction, dramatically shortening the battery life. Imprint’s technology uses a solid polymer electrolyte combined with zinc that overcomes the problem.
First, as we have already touched on: flexibility. Because of the production technique, very thin batteries can be produced that with the absence of a casing can be molded to just about any shape and made extremely small, opening up applications such as freshness indicator labels on food, or incorporated into jewelry or medical devices for use inside the body.
More advantages, and the implications for future zinc demand, in Part Two.