Professor Liu Yong's research group at the School of Materials Science and Engineering of Sun Yat-sen University has recently made important progress in the research of highly resistant metal films and foldable lithium ion batteries. The related results were published in Energy Storage Materials (CiteScore: 13.31) published by ELSEVIER.
Wearable devices with thin, flexible, and foldable performance will be an emerging high-tech market with huge potential. The integration of power supplies, circuits, and functional electronic components (such as sensors, communication equipment, and smart chips) into clothing to make smart clothes is considered to be the most important development direction for future wearable devices. At the same time, the development of foldable Google glasses, foldable mobile phones, foldable radio frequency identification tags, electronic newspapers, and variable electronic products will facilitate portability. This requires that the aforementioned wearable portable device must withstand a significant number of folds. Therefore, for the above-mentioned wearable device applications, it is urgently needed to develop a highly resistant metal film and a foldable lithium ion battery for connecting circuits, functional thin film conductive substrates, battery current collectors, and power supplies.
Recently, Associate Researcher Yu Xiao from Professor Liu Yong's research group used the pyramid structure on the flocked monocrystalline silicon wafer as a template to restore and grow a highly resistant nickel film with an inverted pyramid structure. The prepared 5 μm-thick nickel film has an electrical conductivity as high as 1.25 × 10 5 S / cm (equivalent to 88% of bulk nickel). The stress generated during folding by tangentially dispersing the pyramidal surface and edges of the inverted pyramid greatly improves the folding resistance of the nickel film. It was folded completely outwards (180 °) at 22,000 times and folded inwardly at 18,000 times (180). °), the change rate of the sheet resistance at the crease of the nickel film from the initial value is only 0.19% and 0.72%. A foldable lithium-ion battery prepared with a high-fold-resistant nickel film as a current collector has a capacity retention rate of 98.4% after 5,000 full folds (180 °) during a 20 C rate charge and discharge process. At the same time, it also showed the application of the foldable lithium-ion battery integrated in the Google Glass model. The battery can continue to supply power to the LED light during 9,000 folds (90 °).