3D Self-Supported NiS₂/Ti₃C₂Tx-CC Composite Electrode for High-Performance Flexible Supercapacitors

Abstract

In this paper, a flexible self-supported electrode based on the porous composite of NiS₂ and Ti₃C₂T_x grown on carbon cloth (NiS₂/Ti₃C₂T_x-CC) was designed and synthesized. Due to the introduction of highly conductive and flexible Ti₃C₂T_x, the NiS₂/Ti₃C₂T_x-CC electrode achieves a 1.4-fold increase (1214 C g^-1 at 2 A g^-1) in the specific capacity, a 1.3-fold increase in the rate capability (63% of capacity retention with the current density increases from 2 to 20 A g^-1), and a 2.0-fold increase in the cyclic stability (∼83% of capacity retention at the current density of 20 A g^-1 after 2000 charge–discharge cycles) compared with the NiS₂-CC electrode. Meanwhile, there is no obvious capacity attenuation at the bending angle of 180°, indicating the prominent flexibility of the NiS₂/Ti₃C₂T_x-CC electrode. Accordingly, an all-solid asymmetric supercapacitor (ASC) is fabricated, which exhibits a high energy density of 57.55 Wh kg^-1 at the power density of 800 W kg^-1. Furthermore, ∼97% of initial capacity is maintained at the current density of 5 A g^-1 after 1000 charge–discharge cycles, indicating the good cycling stability. These satisfactory electrochemical behaviors can be also ascribed to the introduction of Ti₃C₂T_x, which can facilitate the rapid electron transport at the interface of the composite and maintain the outstanding mechanical integrality of the electrode during charge–discharge processes.

Keywords:

• MXene
• sulfide
• self-supported
• flexible electrode

Acknowledgements

This study was funded by the Fundamental Research Funds of the Central Universities (2020CDCGJ002; 2019CDXYWL0029; and 2018CDJDWL0011), the Natural Science Foundation of Chongqing (cstc2019jcyj-msxmX0566, cstc2018jcyjAX0450, cstc2018jcyjA2923, and cstc2017jcyjAX0393), the Projects of President Foundation of Chongqing University (2019CDXZWL002), the Opening Project of State Key Laboratory of Luminescence and Applications (SKLA-2020–10), Chongqing Key Laboratory of Micro/Nano Materials Engineering and Technology (KFJJ1301), and the Sharing Fund of Large-scale Equipment of Chongqing University (202003150060 and 202003150078). We also thank Analytical and Testing Center of Chongqing University for performing XRD, XPS and SEM tests.

Disclosure statement

The authors declare that they have no conflict of interest.