Enhanced activity of highly conformal and layered tin sulfide (SnSx) prepared by atomic layer deposition (ALD) on 3D metal scaffold towards high performance supercapacitor electrode

摘要

Layered Sn-based chalcogenides and heterostructures are widely used in batteries and photocatalysis, but its utilizations in a supercapacitor is limited by its structural instability and low conductivity. Here, SnSsubx/sub thin films are directly and conformally deposited on a three-dimensional (3D) Ni-foam (NF) substrate by atomic layer deposition (ALD), using tetrakis(dimethylamino)tin [TDMASn, ((CHsub3/sub)sub2/subN)sub4/subSn] and Hsub2/subS that serves as an electrode for supercapacitor without any additional treatment. Two kinds of ALD-SnSsubx/sub films grown at 160?°C and 180?°C are investigated systematically by X-ray diffractometry, Raman spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy (TEM). All of the characterization results indicate that the films deposited at 160?°C and 180?°C predominantly consist of hexagonal structured-SnSsub2/sub and orthorhombic-SnS phases, respectively. Moreover, the high-resolution TEM analyses (HRTEM) reveals the (001) oriented polycrystalline hexagonal-SnSsub2/sub layered structure for the films grown at 160?°C. The double layer capacitance with the composite electrode of SnSsubx/sub@NF grown at 160?°C is higher than that of SnSsubx/sub@NF at 180?°C, while pseudocapacitive Faradaic reactions are evident for both SnSsubx/sub@NF electrodes. The superior performance as an electrode is directly linked to the layered structure of SnSsub2/sub. Further, the optimal thickness of ALD-SnSsubx/sub thin film is found to be 60?nm for the composite electrode of SnSsubx/sub@NF grown at 160?°C by controlling the number of ALD cycles. The optimized SnSsubx/sub@NF electrode delivers an areal capacitance of 805.5?mF/cmsup2/sup at a current density of 0.5?mA/cmsup2/sup and excellent cyclic stability over 5000 charge/discharge cycles.