A Novel Coating‐Extrusion Method Enabled, High Energy, Power Density, and Scalable Production in Monolithically Integrated Energy Storage Fibers

The rise of wearable electronics demands flexible energy storage solutions like flexible fiber energy storage devices (FESDs), known for their flexibility and portability. However, it remains difficult for existing fabrication methods (typically, finite-coating, thermal-drawing, and solution-extrusion) to simultaneously achieve desirable electrochemical performances and fast production of FESDs. Here, a new scalable coating-extrusion method is developed, utilizing a novel extruded spinneret with tapered apertures to create dual pressure zones. These attributes reduced porosity, enhanced electrode materials loading, and stabilized the interface between the fiber electrode and gel electrolyte of FESDs, enabling the integration of three functional electrodes for the fabrication of both fiber LMO-LTP batteries and fiber LMO/LTP-AC hybrid supercapacitor within a single energy storage device. The resultant multifunctional device achieved a high specific capacity of 89.4 mAh g^-1 in battery mode and demonstrated excellent rate performance of 20 C with nearly 50% capacity retention in supercapacitor mode, with a production rate of 6000 km year^-1.