Chen Weihua, Tang Jiancheng, Cheng Peidong, Ai Yunlong, Xu Yi, Ye Nan
School of Material Science and Engineering, Nanchang University, No. 999, Xuefu Avenue, Nanchang 330031, China.
School of Materials Science and Engineering, Nanchang Hangkong University, No. 696, South Fenhe Avenue, Nanchang 330063, China.
Materials (Basel). 2022 Jan 25;15(3):925. doi: 10.3390/ma15030925.
2D layered MXene (TiCT) with high conductivity and pseudo-capacitance properties presents great application potential with regard to electrode materials for supercapacitors. However, the self-restacking and agglomeration phenomenon between TiCT layers retards ion transfer and limits electrochemical performance improvement. In this study, a 3D porous structure of TiCT was obtained by adding alkali to a TiCT colloid, which was followed by flocculation. Alkaline-induced flocculation is simple and effective, can be completed within minutes, and provides 3D porous networks. As 3D porous network structures present larger surface areas and more active sites, ions transfer accelerates, which is crucial with regard to the improvement of the superior capacitance and rate performance of electrodes. The sample processed with KOH (K-a-TiCT) exhibited a high capacity of approximately 300.2 F g at the current density of 1 A g. The capacitance of the samples treated with NaOH and LiOH is low. In addition, annealing is essential to further improve the capacitive performance of TiCT. After annealing at 400 °C for 2 h in a vacuum tube furnace, the sample treated with KOH (K-A-TiCT) exhibited an excellent specific capacitance of approximately 400.7 F g at a current density of 1 A g, which is considerably higher than that of pristine TiCT (228.2 F g). Furthermore, after 5000 charge-discharge cycles, the capacitance retention rate reached 89%. This result can be attributed to annealing, which can further remove unfavourable surface groups, such as -F or -Cl, and then improve conductivity capacitance and rate performance. This study can provide an effective approach to the preparation of high-performance supercapacitor electrode materials.
具有高导电性和赝电容特性的二维层状MXene（TiCT）在超级电容器电极材料方面具有巨大的应用潜力。然而，TiCT层之间的自堆叠和团聚现象阻碍了离子转移，限制了电化学性能的提升。在本研究中，通过向TiCT胶体中添加碱，随后进行絮凝，获得了TiCT的三维多孔结构。碱诱导絮凝简单有效，可在几分钟内完成，并提供三维多孔网络。由于三维多孔网络结构具有更大的表面积和更多的活性位点，离子转移加速，这对于提高电极的优异电容和倍率性能至关重要。用KOH处理的样品（K-a-TiCT）在1 A g的电流密度下表现出约300.2 F g的高容量。用NaOH和LiOH处理的样品电容较低。此外，退火对于进一步提高TiCT的电容性能至关重要。在真空管炉中于400°C退火2 h后，用KOH处理的样品（K-A-TiCT）在1 A g的电流密度下表现出约400.7 F g的优异比电容，大大高于原始TiCT（228.2 F g）。此外，经过5000次充放电循环后，电容保持率达到89%。这一结果可归因于退火，它可以进一步去除不利的表面基团，如-F或-Cl，进而提高导电性、电容和倍率性能。本研究可为制备高性能超级电容器电极材料提供一种有效方法。
