A novel compact cathode using sponge-like RANEY® nickel as the sulfur immobilizer for lithium–sulfur batteries

Abstract

A novel sulfur immobilizer named RANEY® nickel is introduced for lithium–sulfur batteries for the first time. The sulfur/RANEY® nickel (S/RN) composite is prepared via an accessible solvent method. The key feature of RANEY® nickel is that it contains poriferous channels, which act as barriers against the loss of active materials due to physical and chemical adsorption during discharge/charge cycling. The chemical adsorption of RANEY® nickel for sulfur, verified using X-ray photoelectron spectroscopy (XPS), leads to the generation of Ni–S chemical bonds. In addition, RANEY® nickel, possessing excellent conductivity, can improve the reaction kinetics of an electrode with a high rate capability. As a result, the S/RN cathode presents an initial discharge capacity of 1469 mA h g⁻¹, achieving a minimal capacity fade of 0.12% per cycle after 500 cycles at the rate of 0.5C with an excellent coulombic efficiency of around 99%. Furthermore, the S/RN cathode is promising for use in compact batteries due to its high volumetric specific capacity.