2D Carbide MXene under postetch low-temperature annealing for high–performance supercapacitor electrode. (1st November 2020)

• Record Type: Journal Article
• Authors: Zhang, Zhirong; Yao, Zhongping; Zhang, Xiao; Jiang, Zhaohua
• Is Part Of: Electrochimica acta. Volume 359(2020)
• Publication Date: 2020-11-01
• Subjects: MXenes -- Annealing -- Supercapacitors; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2020.136960
• Languages: English
• ISSNs: 0013-4686

Abstract

Highlights: Changes of structure and surface functional groups of MXene during low-temperature annealing was studied. Low-temperature annealing freestanding MXene films was better than the high-temperature annealing. 200-Ti3 C2 Tx electrode exhibits a high capacitance of 429 F/g, 25% higher than pristine Ti3 C2 Tx . Energy density of 29.2 Wh/Kg was achieved in 200-Ti3 C2 Tx electrode. Abstract: MXene, as an emerging class of conductive two-dimensional materials, have extraordinary applications in the field of electrochemical energy storage. However, the intrisic capacity of MXene still need to be improved due to the large gap to their theoretical capacity. Here, we provide a facile and new strategy to enhance their electrochemical performance—postetch low-temperature annealing (below 400 °C) under Ar atmosphere. Due to the formation of more C-Ti-O active sites and larger interlayer voids, the Ti3 C2 Tx freestanding film annealed under 200 °C exhibits a high capacitance of 429 F/g and energy density of 29.2 Wh/Kg in 1 M H2 SO4 electrolyte, it could withstand 5000 cycles with 89% of the capacitance retention. By comparison, the Ti3 C2 Tx annealed at higher temperature (400 °C), presented a high resistance and poor electrochemical property because of partial oxidation and breaking of Ti-C bond on the surface of MXene nanosheets, despite the larger interlayer voids and low –F contents, . This work is not only probing the importance to maintain the original structure of MXene but also proposing a new strategy to realizing a high capacitance of pure MXene electrode. Graphical abstract: Image, graphical abstract