Screen-printable films of graphene/CoS 2 /Ni 3 S 4 composites for flexible and arbitrary-shaped all-solid-state hybrid supercapacitor device

© 2019 Elsevier Ltd Supercapacitors are attracting increasing research interest because they are expected to achieve battery-level 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 arbitrary-shaped supercapacitor devices still faces enormous challenges. Herein, a 3D-network, porous graphene/CoS 2 /Ni 3 S 4 (G/CoS 2 /Ni 3 S 4 ) composite electrode has been designed and synthesized through a combination of solvothermal and vulcanization methods. By combining the networked CoS 2 /Ni 3 S 4 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/CoS 2 /Ni 3 S 4 ||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.