Autonomous self-healing strategy for flexible fiber lithium-ion battery with ultra-high mechanical properties and volumetric energy densities

Abstract

The development of wearable devices urgently requires flexible, lightweight, and high-performance power solutions. Flexible fiber batteries are flexible and deformable, which holds great potential in this field. However, it still face significant challenges in achieving excellent electrochemical performance and good mechanical properties. Herein, we developed a new method for preparing flexible fiber lithium-ion batteries by surface etching and in-situ chemical cross-linking strategies using direct ink writing-based 3D printing technology. On the one hand, the surface of graphene oxide undergoes oxidation and etching to form pores. This unique pore structure provides additional channels for ions, which increases the ion transmission rate. On the other hand, polyvinyl alcohol/sodium metaborate is introduced into the printing ink/coagulation bath. In-situ chemical cross-linking occurs during the printing and curing process, which exhibits self-healing properties. The flexible fiber electrode has excellent strain (∼30 %) at the macro level, and the assembled fiber lithium-ion battery exhibits impressive volumetric energy density (157.9 mWh cm−3), which exceeds previously reported flexible fiber batteries. And it is also integrated into wearable smart watches for use in daily life. This work proposes an innovative method to fabricate high-performance flexible fiber electrodes, which is of great significance for promoting the development of future portable/wearable electronics.