3D Printed Supercapacitors toward Trinity Excellence in Kinetics, Energy Density, and Flexibility

Abstract Modern electronics place stringent requirements on power supplies, calling for high energy and power density within restricted footprints. 3D printing allows for customized electrode designs with outstanding loading densities and represents a seemingly promising solution. However, the sluggish mass transport within bulky matrices presents serious issues to charge storage kinetics. Doping engineering in conjunction with 3D printing is used to achieve a state‐of‐the‐art areal capacitance of 11.8 F cm −2 , which is among the best for carbonaceous supercapacitors, results in an electrode heavily loaded at 85.1 mg cm −2 . Simultaneously, an uncompromised kinetic performance rivaling high‐rate thin films is delivered, allowing for flash‐charging within 3.6 s while keeping 78.1% capacitance. In agreement with theses appealing features, an unprecedented energy density of 0.66 mWh cm −2 and power density of 1039.8 mW cm −2 for a symmetrical device are registered. Meanwhile, the printed device is equipped with superb mechanical compliance, a rarely achieved, yet gravely desired attribute for 3D printed energy storage devices. This work suggests that flexible energy storage devices with unimpaired kinetics at extremely large loading densities could be realized, therefore overturning the traditional mindset that such a performance can only be achieved in thin film devices which are, however, incapable of securing a large energy output.