Hierarchical Cobalt-Nickel Double Hydroxide Arrays Assembled on Naturally Sedimented Ti3C2Tx for High-Performance Flexible Supercapacitors

作者：Bai, Zuxue; Zhang, Deyang; Guo, Ying; Yang, Ya; Yan, Hailong; Wang, Yangbo; Cheng, Jinbing; Chu, Paul K.; Pang, Huan^*; Luo, Yongsong

来源：Advanced Sustainable Systems, 2022, 6(3): 2100371.

DOI：10.1002/adsu.202100371

• flexible electrodes
• hierarchical structures
• high-rate capability
• naturally sedimented
• supercapacitors
• Ti3C2Tx

Flexible electrodes with excellent energy storage and conversion properties that can be produced by a simple process are highly desirable for supercapacitors. Herein, Cobalt-Nickel double hydroxide (CoNi-DH) micro-nanosheet arrays are prepared uniformly on naturally sedimented Ti3C2Tx films by an etching-deposition-growth process to form a CoNi-DH@Ti3C2Tx heterostructure. The naturally sedimented Ti3C2Tx film serves as the substrate to minimize aggregation of the CoNi-DH nanoarrays to enhance the electrical conductivity. Furthermore, the hierarchical structure comprised of the CoNi-DH interconnected nanoarrays promotes electrolyte access. By taking advantage of the excellent electrical conduction and high theoretical specific capacitance, the flexible CoNi-DH@Ti3C2Tx electrode in the supercapacitor delivers a superior specific capacitance of 919.5 F g(-1) at 1 A g(-1), and remarkable capacitance retention of 89.6% after 5000 cycles at 20 A g(-1). Density-functional theory calculations are performed to investigate the charge density difference and partial density of states of CoNi-DH@Ti3C2Tx and the theoretical assessment suggests that the chemical bonds between Ti3C2Tx and CoNi-DH are critical to the charge transport, electrical conductivity, and structural stability.