Ma Rui, Zhang Xujing, Zhuo Jingting, Cao Lingyun, Song Yutong, Yin Yajiang, Wang Xiaofeng, Yang Guowei, Yi Fang
School of Materials Science and Engineering, Sun Yat-sen University, Guangzhou 510275, P. R. China.
Department of Precision Instrument, Tsinghua University, Beijing 100084, P. R. China.
ACS Nano. 2022 Jun 28;16(6):9713-9727. doi: 10.1021/acsnano.2c03351. Epub 2022 May 18.
MXenes have shown great potential for supercapacitor electrodes due to their unique characteristics, but simultaneously achieving high capacitance, rate capability, and cyclic stability along with good mechanical flexibility is exceptionally challenging. Here, highly enhanced capacitance, rate capability, and cyclic stability, as well as good mechanical flexibility for TCT MXene-based supercapacitor electrodes are simultaneously obtained by engineering the electrode structure, modifying the surface chemistry, and optimizing the fabrication process an optimized integration approach. This approach combines and more importantly optimizes three methods that all require a calcination process: carbonizing grown polymer ("C") on the MXene, alkali treatment ("A"), and template sacrificing ("P"); and the optimized processes lead to more abundant active sites, faster ion accessibility, better chemical stability, and good mechanical flexibility. The obtained P-MXene/C-A electrodes are binder-free and self-supporting and not only have good mechanical flexibility but also demonstrate much larger capacitances and better rate performance than the pristine MXene electrode. Specifically, the P-MXene/C-A electrode (PAQ: quinone-amine polymer) achieves a high capacitance of 532.9 F g at 5 mV s, together with superior rate performance and improved cyclic stability (97.1% capacitance retention after 40 000 cycles at 20 A g) compared with the pristine MXene (79.6% retention) and P-MXene-A (77.3% retention) electrodes. In addition, it is discovered that carbonizing grown polymers can variously remove the -F group and the removal effect can be accumulated with that by the alkali treatment.
由于其独特的特性，MXenes在超级电容器电极方面展现出了巨大潜力，但要同时实现高电容、倍率性能和循环稳定性以及良好的机械柔韧性极具挑战性。在此，通过设计电极结构、修饰表面化学性质以及优化制备工艺（一种优化的集成方法），基于TCT MXene的超级电容器电极同时获得了高度增强的电容、倍率性能和循环稳定性以及良好的机械柔韧性。这种方法结合且更重要的是优化了三种都需要煅烧过程的方法：碳化在MXene上生长的聚合物（“C”）、碱处理（“A”）和模板牺牲（“P”）；并且优化后的工艺导致了更丰富的活性位点、更快的离子可及性、更好的化学稳定性以及良好的机械柔韧性。所制备的P-MXene/C-A电极无粘结剂且自支撑，不仅具有良好的机械柔韧性，而且与原始MXene电极相比还展现出更大的电容和更好的倍率性能。具体而言，P-MXene/C-A电极（PAQ：醌胺聚合物）在5 mV s时实现了532.9 F g的高电容，与原始MXene（79.6%保留率）和P-MXene-A（77.3%保留率）电极相比，具有卓越的倍率性能和改善的循环稳定性（在20 A g下40000次循环后电容保留率为97.1%）。此外，发现碳化生长的聚合物可以不同程度地去除-F基团，并且去除效果可以与碱处理的效果累积。
