Controllable Synthesis of Atomically Thin Type-II Weyl Semimetal WTe2 Nanosheets: An Advanced Electrode Material for All-Solid-State Flexible Supercapacitors

5 years ago

Controllable Synthesis of Atomically Thin Type-II Weyl Semimetal WTe2 Nanosheets: An Advanced Electrode Material for All-Solid-State Flexible Supercapacitors

Zheng Liu, Hua Zhang, Qingsheng Zeng, Zhuangchai Lai, Bijun Tang, Wei Fu, Peng Yu, Kazu Suenaga, Cheng Yan, Junhao Lin

Compared with 2D S-based and Se-based transition metal dichalcogenides (TMDs), Te-based TMDs display much better electrical conductivities, which will be beneficial to enhance the capacitances in supercapacitors. However, to date, the reports about the applications of Te-based TMDs in supercapacitors are quite rare. Herein, the first supercapacitor example of the Te-based TMD is reported: the type-II Weyl semimetal 1Td WTe2. It is demonstrated that single crystals of 1Td WTe2 can be exfoliated into the nanosheets with 2–7 layers by liquid-phase exfoliation, which are assembled into air-stable films and further all-solid-state flexible supercapacitors. The resulting supercapacitors deliver a mass capacitance of 221 F g−1 and a stack capacitance of 74 F cm−3. Furthermore, they also show excellent volumetric energy and power densities of 0.01 Wh cm−3 and 83.6 W cm−3, respectively, superior to the commercial 4V/500 µAh Li thin-film battery and the commercial 3V/300 µAh Al electrolytic capacitor, in association with outstanding mechanical flexibility and superior cycling stability (capacitance retention of ≈91% after 5500 cycles). These results indicate that the 1Td WTe2 nanosheet is a promising flexible electrode material for high-performance energy storage devices. The first Te-based transition metal dichalcogenide supercapacitor, 1Td WTe2, is successfully fabricated by liquid exfoliation of bulk samples into nanosheets with 2–7 layers, and subsequent device assembly, which achieves mass and stack capacitances of 221 F g−1 and 74 F cm−3, and volumetric energy and power densities of 0.01 Wh cm−3 and 83.6 W cm−3.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/adma.201701909