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

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.