Core-sheath 3D printing of highly conductive and MoS2-loaded electrode with pseudocapacitive behavior

Abstract

Pseudocapacitance holds great promise for energy density improvement of supercapacitors. However, how to enable a pseudocapacitor with combined feature of high mass loading of pseudocapacitive material, efficient ion/electron transport, as well as facile and scalable manufacturing, still remains a significant challenge. Herein, we demonstrated an efficient and scalable extrusion-based core-sheath 3D printing strategy for directly and controllably constructing pseudocapacitive carbon nanotube (CNT)- MoS2 (CM)-CNT/graphene electrode, with high mass loading up to 55% and uniform distribution of MoS2, hierarchically porous configuration and highly interconnected conductive network framework built by coupling graphene scaffold located in shell layer and CNTs situated in core layer. The unique architecture featuring adequate channels and pathways can act as a “superhighway” for ultrafast ion diffusion and electron transport throughout the entire device, thereby enabling fast kinetics of Faradaic reactions and abundant availability of electrochemical active sites. A symmetric pseudocapacitor assembled with 3D-printed electrode and in situ electrospun poly(vinylidene fluoride) (PVDF) nanofiber separator delivered high specific capacitance (558 mF cm−2) and energy density (49 µWh cm−2), remarkable cycling stability (87% after 8000 cycles), and superior capacity even at large electrode thickness. This work has shed light on new strategies for designing and fabricating high-performance pseudocapacitors toward future uses.