A group of researchers in China has developed a unique fiber that could store adequate electricity to charge personal gadgets and wearable medical devices. These developments would spur on the need for “flexible energy storage“.
A study published last week revealed that researchers with Fudan University in Shanghai said they managed to mass-produce fiber batteries that hold 85.69 watt-hours of electricity per kilogram. In comparison, an iPhone 12 Pro Max, which weighs 228 grams, has a battery of about 14 watt-h hours’ power capacity.
The scientists demonstrated charging a smartphone wirelessly while wearing a shirt made with fiber batteries. As part of the wearable trend, smart clothes have attracted much commercial interest in recent years.
The latest products include smart socks that track your foot-landing techniques, swimsuits that can remind you to put on sunscreen, and yoga pants that can sense when your posture needs adjusting.
Scientists display A Smartphone Charging With Fiber Batteries. Photo Credit: Peng Huisheng
It was revealed that most of the wearables are powered by conventional lithium-ion batteries, which are not usually foldable or waterproof. The latest study brings researchers closer to developing a commercially viable textile battery that could open up new possibilities for wearable devices.
What Is Lithium-ion Batteries?
A lithium-ion (Li-ion) battery is an advanced battery technology that uses lithium ions as a key component of its electrochemistry. It is a family of rechargeable battery types in which lithium ions move from the negative electrode to the positive electrode during discharge and back when charging.
In the latest study, researchers made fiber-shaped lithium-ion batteries by winding an aluminum wire coated with lithium cobalt oxides – the positive electrode – together with a graphite-coated copper wire for the negative electrode. Special wrappings are applied between the two to prevent short-circuiting.
The scientists then discovered that as the fiber’s length increases, its internal resistance decreases, before leveling off. Based on the discovery, they designed an industrial process to produce fiber batteries that were meters long and could be woven into textiles.
According to the study, the material retained 90.5 percent of its capacity after 500 rounds of charge-discharge. The battery-textile worked well even as it was being folded, washed with water and punched through by a knife, researchers found.
In one of the experiments led by Peng Huisheng, a piece of the textile continued charging an iPad as a 1,300-kilogram car drove on top of it.
Huisheng told the Chinese news outlet Thepaper.cn that the fiber’s energy density, which measures the amount of energy a battery contains in proportion to its weight, still lags behind conventional batteries.
But with sufficient funding and technical support, these types of materials could possibly enter commercial use in two to five years, Huisheng said.
Zijian Zheng, a professor who studies wearable electronics with the Hong Kong Polytechnic University, said the lack of textile batteries had become a key shortcoming for wearable electronics.
“You have to put your battery somewhere, with a cable linked to the device,” said Zheng, who is not associated with the study. “The advantage of the material published in this paper is that it looked like fiber, so it could be seamlessly integrated into your fabric structure.”
What Are Wearable Electronics?
Wearable electronics are electronic devices constantly worn by a person as invisible as clothing to provide intelligent assistance that augments memory, intellect, creativity, communication and physical senses and can be worn internally as implantable devices such as pacemakers and neuroprosthetics.
Zheng said the authors of the new study demonstrated that it’s possible to make a fiber-shaped battery that’s hundreds of meters long, bringing the material a step closer to commercial applications. He also said that his own research group had developed a kind of fabric battery that could store energy.