Ultrahigh‐Rate On‐Paper PEDOT:PSS‐Ti2C Microsupercapacitors with Large Areal Capacitance

Abstract The growing demands of sustainable, portable, and wearable electronics pose new demands on miniaturized energy storage devices that can be integrated on flexible substrates such as paper. Microsupercapacitors (MSCs), especially MXene‐based pseudocapacitive MSCs with fast charging/discharging rate, high power density, and long cycle life, are competitive candidates as power supply for emerging flexible and wearable on‐paper electronics. However, few studies have reported MXene‐based on‐paper MSCs to simultaneously attain ultrahigh‐rate (>1000 mV s −1 ) capability and large areal capacitance >10 mF cm −2 . Herein, ultrafast metal‐free on‐paper MSCs are fabricated through leveraging the synergistic effect of conductive PEDOT:PSS and capacitive MXene (Ti 2 C) to achieve a remarkable areal capacitance of 30 mF cm −2 and long lifetime (>96% capacitance retention after 10 000 cycles) at an ultrahigh scan rate of 1000 mV s −1 , outperforming most of the present on‐paper or MXene‐containing MSCs. Moreover, the printed on‐paper metal‐free MSC arrays attain extended working voltage window of up to 6 V and outstanding capacitive performance at an ultrahigh scan rate of 10 V s −1 . The on‐paper PEDOT:PSS‐Ti 2 C composite MSCs offer new opportunities as eco‐friendly microscale power sources for emerging paper‐based portable and wearable electronics.