Highly flexible, mechanically strengthened metallic glass-based composite electrode with enhanced capacitance and cyclic stability

The design of flexible composite electrodes has become the top priority in energy storage devices for the development of future wearable intelligent electronics. However, searching for fully integrated, ultrathin flexible composite electrodes with satisfying electrochemical performance is still a major challenge. Herein, we introduce a nanoporous gold metallic glass (MG) ribbon-based composite electrode with excellent electric conductivity, mechanical flexibility, and extra capacitance by integrating polypyrrole (PPy) into wrinkled nanoporous ribbon (NPG@MG). The "freestanding, ultrathin, highly conductive and flexible" nature of the composite electrode prevents the conducting polymer from structural instability resulting from the volume swell and shrink during the charging/discharging circulation, and the packed PPy provides protection for the wrinkled topology on the surface of the MG ribbon. The capacitance of pure NPG@MG-PPy composite electrode reached 393 mF.cm(-2). The ultra-thin all-solid-state flexible supercapacitor demonstrates an excellent capacitance of 172 mF.cm(-2) (14.8 F.cm(-3)), accompanied by a superior cycling capability after 8000 charge/discharge cycles attributed to mechanical flexibility. The areal energy density also reached 0.74 mWh.cm(-3) (9 mu Wh.cm(-2)) at a power density of 1 mu W.cm(-2). This work provides valuable concepts on the design of PPy-based hybrid materials for flexible energy storage systems with greatly enhanced electrochemical performances.