Batteries Woven Right Into Fabric Boost Wearable Tech

Incorporating solar cells into watch straps and clothing material could make wearable devices more convenient

2 min read
Batteries Woven Right Into Fabric Boost Wearable Tech

The choices in wearable electronics, including Google Glass and a wave of smartwatches, are quickly multiplying. But those pesky batteries—they still need to be plugged into something to charge up. What if your watch strap could contain the battery components, along with a flexible solar cell? Voilà: No more plugging in.

Others have turned to piezoelectrics and nanomaterials to get wearable tech going, but a group at the Korea Advanced Institute of Science and Technology decided to work a lithium-ion battery right into the fabric.

"Although considerable progresses have been seen for wearable electronics, lithium rechargeable batteries, the power sources of the devices, do not keep pace with such progresses due to tenuous mechanical stabilities, causing them to remain as the limiting elements in the entire technology," wrote researchers led by Yong-Hee Lee in Nano Letters. To that end, they tested various materials which they enmeshed in the wristband.

They came up with a fabric-based battery comprising a nickel-coated polyester yarn as the current collector, polyurethane as a binder holding materials together, and a polyurethane separator. The resulting battery can withstand repeated folding and unfolding and still function, a requirement for any tech that's actually going to wrap around the wrist or be worn in other ways. The batteries exhibited "decent" cycling and rate performance, the researchers wrote. Just as importantly, they said, the methods for fabricating this type of battery already exist and should be scalable quickly.

To keep it charged, they added solar cells—flexible polymer cells (PCDTBT, specifically) on polyethylene naphthalate—to the same bits of fabric. The wristband solar panel achieved a conversion efficiency of 5.49 percent, not bad for flexible polymer cells of this type.

This is all pointing toward a future where your glasses, watch, shirt, and even the walls of your home are transformed by electronics. They'll be data nodes capable of medical monitoring, communications, or whatever else you can dream up. And they won't ever need to plug into a power source.

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This Dutch City Is Road-Testing Vehicle-to-Grid Tech

Utrecht leads the world in using EVs for grid storage

10 min read
This photograph shows a car with the words “We Drive Solar” on the door, connected to a charging station. A windmill can be seen in the background.

The Dutch city of Utrecht is embracing vehicle-to-grid technology, an example of which is shown here—an EV connected to a bidirectional charger. The historic Rijn en Zon windmill provides a fitting background for this scene.

We Drive Solar

Hundreds of charging stations for electric vehicles dot Utrecht’s urban landscape in the Netherlands like little electric mushrooms. Unlike those you may have grown accustomed to seeing, many of these stations don’t just charge electric cars—they can also send power from vehicle batteries to the local utility grid for use by homes and businesses.

Debates over the feasibility and value of such vehicle-to-grid technology go back decades. Those arguments are not yet settled. But big automakers like Volkswagen, Nissan, and Hyundai have moved to produce the kinds of cars that can use such bidirectional chargers—alongside similar vehicle-to-home technology, whereby your car can power your house, say, during a blackout, as promoted by Ford with its new F-150 Lightning. Given the rapid uptake of electric vehicles, many people are thinking hard about how to make the best use of all that rolling battery power.

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