Ultrathin Layers with Large Contact Area on Carbon Fibers as High-Performance Electrode

Rechargeable batteries are essential for powering our personal electronic devices. To meet the novel functions of next-generation electronics, including foldable displays, flexible power sources are needed. However, conventional batteries are rigid and unable to adapt to the demands of flexible devices. Low-cost, rechargeable batteries containing naturally abundant elements, such as zinc, are appealing, but flexible batteries based on zinc require a different preparation method from conventional batteries.

In their article in Advanced Energy Materials, Xu Chen, Bin Liu, Cheng Zhong, and co-workers have developed a high-performance, flexible air electrode for the Zn–air battery by devising a simple fabrication technique.

The technique involves electrodeposition with fast heat treatment to grow ultrathin mesoporous Co3O4 layers on the surface of carbon fibers on a carbon cloth. These ultrathin Co3O4 layers have a maximum contact area on the conductive support, facilitating rapid electron transport and preventing the aggregation of the layers.

Benefiting from the high utilization degree of active materials and rapid charge transport, the mass activity for oxygen reduction and evolution reactions of the ultrathin electrode is more than 10 times higher than that of the carbon cloth loaded with commercial Co3O4 nanoparticles. The as-assembled flexible Zn–air battery based on the ultrathin electrode exhibits excellent rechargeability (≈1.03 V discharge voltage and ≈1.95 V charge voltage at 2 mA cm–2), with a high charge density of 546 Wh kg–1. It also has a high cycling stability, where no obvious loss occurred after 10 hours of galvanostatic discharge–charge testing or after 300 mechanical bending cycles.

The authors also integrated a flexible display into the device. Despite repeated bending and twisting, the device maintains its mechanical integrity and discharge performance. When the device is cut by scissors, there is no perceptible change in the display brightness, signaling safe and reliable operation if the device is damaged.

To find out more about this flexible battery, please visit the Advanced Energy Materials homepage.


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