Many times, when people go out, they will encounter the situation that the mobile phone is out of power and forget to bring the power bank and charger, which brings certain inconvenience to life. If there is such a piece of clothing, it looks no different from ordinary clothes, but it can wirelessly charge mobile phones and other electronic devices. Isn’t it exciting?

Lithium-ion battery is made into fabric

Recently, researchers from Fudan University have developed a wearable battery fabric that can not only wirelessly charge mobile phones, but also provide sufficient energy for smart fibers that monitor human health data. Moreover, after repeated washing and folding, it can still maintain stable electrochemical and mechanical properties.

The classic plane coating method is difficult to apply to high-curvature fibers, because when the fiber surface is coated, uneven coating such as beads is easily generated on the surface, which seriously affects the continuity and electrochemical performance of the fiber electrode preparation.

However, the team further obtained high-performance and high-safety large-area battery fabrics through weaving methods. They used a 1.5-square-meter "cloth" to demonstrate that the preparation of display devices can be effectively integrated with the fabric weaving process, and multifunctional micro-light emitting devices are integrated at the interweaving points of polymer composite fibers to realize large-area flexible display fabrics and intelligent integrated systems.

In addition, the preparation of fiber lithium ion batteries mainly faces two difficulties. First, the internal resistance of fiber lithium batteries has an important influence on its electrochemical performance, but the relationship between its internal resistance and fiber length is still not very clear; Second, because of the completely different device structure, the electrode preparation and device construction methods for bulk lithium-ion batteries are difficult to apply to fiber lithium batteries.

After repeated experiments, when the device is 1 meter in length, the fiber lithium-ion battery has a capacity of 25mAh, which can provide more than 2 days of power for commercial wearable devices such as heart rate monitors and oximeters. The energy density based on the overall mass exceeds 85 Wh/kg.

At the same time, fiber lithium-ion batteries have good cycle stability. After 500 cycles, the battery capacity retention rate still reached 90.5%, and the coulombic efficiency was 99.8%. Even in the case of a radius of curvature of 1cm, the capacity retention rate of the fiber lithium ion battery after bending 100,000 times is still greater than 80%.

In general, this fully flexible fabric can not only wirelessly charge mobile phones and other electronic devices, but also has the advantages of wear-resistant, foldable, and machine-washable repeatedly. Moreover, its price is US$0.05 per meter, laying a good foundation for mass production.