Screen-printable films of graphene/CoS2/Ni3S4 composites for the fabrication of flexible and arbitrary-shaped all-solid-state hybrid supercapacitors

Supercapacitors are attracting increasing research interest because they are expected to achieve batterylevel energy density while having a long calendar life and a short charging time. However, the development of large-scale and cost-reasonable production methods for flexible, wearable and arbitraryshaped supercapacitor devices still faces enormous challenges. Herein, a 3D-network, porous graphene/CoS2/Ni3S4 (G/CoS2/Ni3S4) composite electrode has been designed and synthesized through a combination of solvothermal and vulcanization methods. By combining the networked CoS2/Ni3S4 nanoflakes with reduced graphene oxide (RGO) nanosheets, the as-prepared composite electrode exhibits good conductivity, a high density of electrochemically active sites and good cycling stability. The result is a high specific capacitance of 1739 F g(-1) at a current density of 0.5 A g(-1). Significantly, the arbitrary-shaped G/CoS2/Ni3S4 parallel to GF hybrid supercapacitor devices can be printed directly on different substrates, which favorably combine mechanical flexibility, good cycling performance and high energy density. This methodology may be feasible to prepare fully-printable and wearable supercapacitors, and other electronic devices in large scale, thereby holding enormous potential for wearable technologies. (c) 2019 Elsevier Ltd. All rights reserved.