Ultrafast self-expanded reduced graphene oxide and 2D MoS2 based films as anode in Li-ion battery

Abstract

In this paper, thin free standing films based on ultrafast self-expanded reduced graphene oxide (ERGO) and exfoliated molybdenum disulfide (ex-MoS2) were prepared via vacuum-assisted filtration and tested as anodes in Li-ion half-cells. Three films with GO to ex-MoS2 ratio of 1:1, 1:2 and 2:1 were assembled (ERGO/MoS2–1, ERGO/MoS2–2, ERGO/MoS2–3, respectively). Reduction of GO-based films was conducted via ultrafast self-expanded reaction (USER) in Ar atmosphere. This process not only immediately reduced GO but also significantly expanded films structure. The sample with the highest specific capacity and the highest stability consisted of GO and ex-MoS2 with ratio of 1:1. The anode composed of this film showed approximately 6 times higher discharge capacity (916 mAh/g at 50 mA/g) than reference film (RGO/MoS2–1) where graphene oxide was thermally reduced in a furnace (145 mAh/g at 50 mA/g). Such high performance is associated with the expanded structure of ERGO allowing better lithiation yield and served as a protection of ex-MoS2 against overexpanding upon charging/discharging process. What is more, the proposed Li-ion half-cells are free of any non-active materials e.g. carbon black or poly(vinyl difluoride) which are commonly used in batteries increasing the cost of the whole energy storage device.