Fractal fern-like PbS hierarchical architectures for supercapacitors with excellent long-term cycling stability

This work describes a facile one-step method to synthesize PbS hierarchical architectures with excellent supercapacitive performance. The as-prepared PbS sample shows a self-similar fern-like morphology. A unit has four or eight micro-trunks with the size of 10 +/- 1 mu m, which consist of ordered secondary nano-leaves with the thickness of 200 +/- 20 nm and the spacing of about 100 nm. The fractal fern-like PbS sample owns a high specific capacitance of 498 F/g at a discharge current density of 2 A/g, while the value still retains 74% (369 F/g) at a big discharge current density of 20 A/g. The equivalent series resistance of the as-prepared sample is only 1.05 Omega. Moreover, the fractal fern-like PbS sample exhibits a surprising long-term durability which can keep 95.9% capacitance retention over 60,000 charge/discharge cycles at a charge/discharge current density of 5 A/g. The as-prepared PbS sample shows a stable energy density of 11.5 Wh/kg at the power density of 200 W/kg, and still remains 8.2 Wh/kg at 4000 W/kg. (C) 2019 Elsevier B.V. All rights reserved.