Wu Szu-Chen, Chang Po-Hsueh, Chou Syun-Hong, Huang Chih-Yang, Liu Ta-Chung, Peng Cheng-Hsiung
Department of Materials Science and Engineering, National Chiao Tung University, 1001 University Road, Hsinchu 300, Taiwan.
Department of Chemical and Materials Engineering, MingHsin University of Science and Technology, 1 Xinxing Road, Xinfeng, Hsinchu 304, Taiwan.
Nanomaterials (Basel). 2020 Nov 30;10(12):2388. doi: 10.3390/nano10122388.
Supercapacitors (SCs) are promising for powering mobile devices, electric vehicles and smart power grids due to their fast charge/discharge rate, high power capability and robust cycle stability. Nitrogen-doped porous carbons are great alternatives because they provide pseudocapacitance without losing their power rate. Nanoporous carbon derived from metal organic frameworks (MOFs) is an ideal precursor for preparing heteroatom-doped carbons due to their abundant nitrogen contents and incredible specific surface areas. However, severe aggregations and the leakage of nitrogen can occur during harsh carbonization. In this study, we used CoAl-LDH (cobalt aluminum layered double hydroxide) as an in-situ growth substrate, allowing Co-based MOF to uniformly grow onto the CoAl-LDH to form a sandwiched MOF/LDH/MOF structure. After acid etching, we obtained waffle-like nanoporous carbons (WNPC). WNPC exhibited high nitrogen and oxygen retention (7.5 wt% and 9.1 wt%) and a broad mesopores distribution with specific surface areas of 594 mg, which promoted a sieving effect. This renders a specific capacitance of 300.7 F·g at 1 A·g and the high retention (72%) of capacitance at 20 A·g, ensuring its use at high-rate supercapacitor electrodes. Finally, the WNPC symmetric supercapacitor reaches a superior specific energy of 27 W·h·kg at a power of 500 W·kg, and a good cycle stability (85% capacitance retention after 10,000 cycles).
超级电容器（SCs）因其快速的充/放电速率、高功率性能和强大的循环稳定性，在为移动设备、电动汽车和智能电网供电方面具有广阔前景。氮掺杂多孔碳是很好的替代品，因为它们能提供赝电容且不损失功率速率。源自金属有机框架（MOFs）的纳米多孔碳是制备杂原子掺杂碳的理想前驱体，因其富含氮且具有惊人的比表面积。然而，在苛刻的碳化过程中会发生严重的团聚和氮泄漏。在本研究中，我们使用CoAl-LDH（钴铝层状双氢氧化物）作为原位生长底物，使钴基金属有机框架均匀生长在CoAl-LDH上，形成夹心式MOF/LDH/MOF结构。经过酸蚀刻后，我们获得了华夫饼状纳米多孔碳（WNPC）。WNPC表现出高的氮和氧保留率（分别为7.5 wt%和9.1 wt%）以及具有594 mg比表面积的宽中孔分布，这促进了筛分效应。这使得在1 A·g时比电容为300.7 F·g，在20 A·g时电容保持率高（72%），确保其可用于高倍率超级电容器电极。最后，WNPC对称超级电容器在功率为500 W·kg时达到27 W·h·kg的优异比能量，并且具有良好的循环稳定性（10000次循环后电容保持率为85%）。
