Facilitating ion transport in porous chemically bonded black phosphorene/MXene heterostructured films for flexible high-rate supercapacitors

Abstract

Developing thick MXene-based electrodes for supercapacitors (SCs) that possess both high specific capacitance and exceptional rate performance has become a critical research focus. However, MXene-based electrodes often face challenges related to the complex and elongated ion diffusion pathway caused by their large aspect ratio and nanosheet restacking, limiting the rate performance. Herein, we propose fabricating porous chemically bonded black phosphorene/Ti3C2Tx heterostructured films co-doped with S/N heteroatoms via electrostatic self-assembly followed by thermal foaming. The incorporation of black phosphorene serves to effectively prevent the restacking of Ti3C2Tx, while the porous structure enhances ion transport. Additionally, the doped heteroatoms significantly boost the electrochemical activity of Ti3C2Tx. The porous films of approximately 50 μm thickness demonstrate a high capacitance of 374 F g-1 at 0.5 A g-1, retaining 84% of the capacitance at 20 A g-1, thereby enabling the assembled SCs to deliver excellent rate performance. This work presents a promising and innovative approach for the development of high-rate MXene-based SCs.