Conductive 2D dithiolene MOF-based electrodes for low-temperature high-performance energy storage

Abstract

Achieving supercapacitors with high-performance operation in a low temperature environment is still a great challenge. Herein, an effective strategy that involves carbon cloth in situ grown 2D conductive dithiolene cobalt/nickel 2,3,6,7,10,11-triphenylenehexathiolate was developed to prepare hierarchical porous electrode materials (HTTP-M(Co/Ni)-CC). Without any conductive additive and binders, the specific capacitance values of HTTP-Co-CC and HTTP-Ni-CC reached up to 83.5 and 103.9 F g⁻¹ at 10 mV s⁻¹, respectively, when working at −60 °C. Compared with room-temperature capacitance values, the capacitance retention of HTTP-Co-CC and HTTP-Ni-CC remain 82.7% and 87.1%, respectively, which presents HTTP-Co-CC and HTTP-Ni-CC as unprecedented MOF electrode materials for use in the field of low-temperature energy storage. The outstanding performance at lower temperature can be attributed to an increased conductivity with decreasing temperature, hierarchical pore structures that facilitate the mass transfer of incompletely desolvated electrolyte ions at the interface and a flexible porous carbon cloth substrate that provides buffer space for volume expansion. This study not only demonstrates conductive dithiolene MOF-based electrodes for low-temperature high-performance energy storage, but also provides a promising prospect for the development of robust MOFs as a new family of active materials for supercapacitors operated under low-temperature environments.