Researchers make a bag to recharge your phone

People may be able to avoid the trouble of trying to look around for power banks to recharge their phones by using their clothes and backpacks to charge mobile phones and other portable electronics.

Such a scenario had been made possible due to a breakthrough by a team led by Peng Huisheng, professor at Fudan's Department of Macromolecular Science and Institute for Fiber Electronic Materials and Devices, which has been published in science journal Nature.

The team has announced the successful development of high-performance wearable fiber batteries with advanced capabilities for energy storage and supply.

At a news conference, they showed a normal looking bag. But when a mobile phone was put in it, the phone screen showed it was being charged.

Researchers said the bag can wirelessly top up a mobile phone battery by 20 to 30 percent in half an hour.

Wearable batteries have been a hot research area around the world with safety, stability, and performance the bottlenecks. Replacement of liquid electrolytes with polymer gel electrolytes is recognized as a general and effective way of solving safety problems and achieving high flexibility in wearable batteries, but the poor interface between polymer gel electrolyte and electrodes, caused by insufficient wetting, produces much poorer electrochemical properties, especially during the deformation of the battery.

The problem had nagged at the team for years until one day Peng was inspired when he saw creepers tightly wound around another plant.

He found that creepers secrete a liquid with good wettability, which can penetrate into the pore structure of the contact surface between the two plants, and then the monomer in the liquid polymerizes glue the creeper to the other plant, entangling them together.

Thus the team designed channel structures in electrodes to incorporate polymer gel electrolytes and to form intimate and stable interfaces for high-performance wearable batteries.

With the solution, the team made several kilometers of fiber lithium-ion batteries with an energy density of 128 watt-hours per kilogram, which can supply electricity for high-powered appliances such as drones.

Researchers said the fiber batteries' performance remains stable over 96 percent after being bent 100,000 times.

The fiber lithium-ion batteries were woven into a textile to provide an output capacity of 2,975 mAh, capable of charging regular mobile phones available on the market, and it worked safely under extreme conditions, such as temperatures of minus 40 to 80 degrees Celsius and in a vacuum. The team said the fiber batteries show promise for applications in firefighting and space exploration.

They are also researching making the fibers capable of generating electricity with solar power so that bags and clothes can not only recharge electronics, but can recharge themselves when the sun shines.