Robust flexible WS 2 /PEDOT:PSS film for use in high-performance miniature supercapacitors

Layered WS2 nanosheet has advantages in the application of energy devices because of its distinctive structure and high electrochemical behaviors. The fabrication of high-quality free-standing WS2 film is anticipant and challenging in developing its flexible and miniature device. Here, using a highly conductive poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as binder, flexible free-standing WS2/PEDOT:PSS film as miniature supercapacitors electrode materials was easily prepared by vacuum filtration method. The WS2/PEDOT:PSS film was characterized by scanning electron microscopy, high resolution transmission electron microscopy, atomic force microscopy, Raman spectrum, X-ray photoelectron spectroscopy and electrochemical technology. The free-standing WS2/PEDOT:PSS film with conductivity of 44 S cm−1 showed a good flexibility, robustly mechanical property and high electrochemical behaviors. The flexible film can bear 300 g weight and be used as a conducting wire in a circuit. The WS2/PEDOT:PSS film with thickness of ~2.1 μm exhibited high areal capacitance of 86 mF cm−2 and volumetric capacitance of 411 F cm−3 at 40 mV s−1 in 1.0 M H2SO4 solution. Besides, the capacitance retention could reach 107% of initial specific capacitance after 5000 charge-discharge cycles. Moreover, the flexible device based on WS2/PEDOT:PSS films could be assembled without any substrates and showed a volumetric capacitance of 87 F cm−3 at 10 mV s−1 and 86% capacitance retention of initial specific capacitance after 5000 cycles. These results implied the flexible free-standing WS2/PEDOT:PSS film has a potential application in flexible and miniature supercapacitors without any other substrates as current collectors.