Tailoring Electronic Structure and Size of Ultrastable Metalated Metal–Organic Frameworks with Enhanced Electroconductivity for High‐Performance Supercapacitors

• Published in: Angewandte Chemie Vol. 133; no. 18; pp. 10316 - 10326
• Main Authors: Xia, Zhengqiang, Jia, Xu, Ge, Xi, Ren, Chongting, Yang, Qi, Hu, Jun, Chen, Zhong, Han, Jing, Xie, Gang, Chen, Sanping, Gao, Shengli
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 26.04.2021
• Subjects: Capacitance; Carrier density; Chemistry; conductivity; Conjugation; Electrical conductivity; Electrical resistivity; Electrodes; Electrolytes; Electronic structure; Energy storage; Hydrophobicity; Intermetallic compounds; Ligands; Metal-organic frameworks; nanocomposites; stability
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.202100123

Utilization of metal–organic frameworks (MOFs) as electrodes for energy storage/conversion is challenging because of the low chemical stability and poor electrical conductivity of MOFs in electrolytes. A nanoscale MOF, Co0.24Ni0.76‐bpa‐200, possessing ultrahigh stability with uncommon semiconductor behavior (σ=4.2×10−3 S m−1) was fabricated. The MOF comprises a robust hydrophobic paddlewheel and an optimized Co/Ni ratio, with consequent control over MOF size and the degree of conjugation of the coligand. A DFT study revealed that appropriate Ni2+ doping reduces the activation energy of the system, thus providing a higher carrier concentration, and the strongly delocalized N‐donor ligand notably increases the metal–ligand orbital overlap to achieve efficient charge migration, leading to continuous through‐bond (‐CoNi‐N‐CoNi‐)∞ conduction paths. These structural features endow the MOF with a good cycling stability of 86.5 % (10 000 cycles) and a high specific capacitance of 1927.14 F g−1 among pristine MOF‐based electrodes. An elaborately designed 3D metal–organic framework (MOF) integrating excellent chemical stability and good conductivity was obtained through a combination of ligand delocalization, activation energy, and morphology parameters. The superiority of the as‐prepared pristine MOF‐based supercapacitor electrode was structurally and electrochemically identified in detail.