3D-Printed Flexible and Integrable Asymmetric Microsupercapacitors with High-Areal-Energy-Density.

Abstract

3D-Printed quasi-solid-state microsupercapacitors (MSCs) present immense potential as next-generation miniature energy storage devices, offering superior power density, excellent flexibility, and feasible on-chip integration. However, the challenges posed by formulating 3D printing inks with high-performance and ensuring efficient ionic transport in thick electrodes hinder the development of advanced MSCs with high areal energy density. Herein, we report 3D-printed ultrahigh-energy-density asymmetric MSCs with latticed electrodes, fabricated using Ni-Co-S/Co(OH)₂/carbon nanotubes/reduced graphene oxide (Ni-Co-S/Co(OH)₂/CNTs/rGO) positive electrode ink and activated carbon (AC)/CNTs negative electrode ink. The latticed electrodes feature abundant hierarchical pores and an interconnected conductive network formed by coupling CNTs and rGO (or AC), enabling efficient ion and electron transport even in thick electrodes. The 3D-printed asymmetric MSCs with three-layer latticed electrodes deliver an impressive areal energy density of 543 μWh cm^-2 and a high areal capacitance of 1.74 F cm^-2 at 1 mA cm^-2, nearly double the performance of planar electrodes under identical conditions. Furthermore, the device demonstrates excellent cycling stability (80% retention of the initial capacitance after 5000 cycles). This work advances the field of 3D printing for energy storage applications and provides design principles for developing integrated flexible MSCs.