Achieving High Pseudocapacitance of 2D Titanium Carbide (MXene) by Cation Intercalation and Surface Modification

作者：Li, Jian; Yuan, Xiaotao; Lin, Cong; Yang, Yanquan; Xu, Le; Du, Xin; Xie, Jinglin; Lin, Jianhua^*; Sun, Junliang^*

来源：Advanced Energy Materials, 2017, 7(15): 1602725.

DOI：10.1002/aenm.201602725

• TRANSITION-METAL CARBIDES
• ENERGY-STORAGE
• CAPACITANCE
• CARBON
• OXIDE
• SUPERCAPACITORS
• ELECTRODES
• LAYERS

Supercapacitors attract great interest because of the increasing and urgent demand for environment-friendly high-power energy sources. Ti3C2, a member of MXene family, is a promising electrode material for supercapacitors owing to its excellent chemical and physical properties. However, the highest gravimetric capacitance of the MXene-based electrodes is still relatively low (245 F g(-1)) and the key challenge to improve this is to exploit more pseudo-capacitance by increasing the active site concentration. Here, a method to significantly improve the gravimetric capacitance of Ti3C2Tx MXenes by cation intercalation and surface modification is reported. After K+ intercalation and terminal groups (OH-/F-) removing, the intercalation pseudocapacitance is three times higher than the pristine MXene, and MXene sheets exhibit a significant enhancement (about 211% of the origin) in the gravimetric capacitance (517 F g(-1) at a discharge rate of 1 A g(-1)). Moreover, the as-prepared electrodes show above 99% retention over 10 000 cycles. This improved electrochemical performance is attributed to the large interlayer voids of Ti3C2 and lowest terminated surface group concentration. This study demonstrates a new strategy applicable to other MXenes (Ti2CTx, Nb2CTx, etc.) in maximizing their potential applications in energy storage.

• 出版日期2017-8-9
• 单位北京大学; 重庆大学