Electrocatalytic effect of 3D porous sulfur/gallium hybrid materials in lithium-sulfur batteries

Lithium-sulfur battery has long been considered as the best choice for the next generation secondary battery. However, the intrinsic insulativity of sulfur and the polysulfide shuttle effect have been the key problems that hinder the commercialization of lithium sulfur batteries. Here, using a facile shearing implement assists thermal synthesis process, in which liquid metal gallium and sulfur (mass ratio1:10) are the only reactants, we create a 3D porous sulfur/gallium hybrid materials (S/Ga). Micro/nanometer liquid metal gallium particles embed in the porous sulfur. The S/Ga cathode lithium cell exhibits a high Coulombic efficiencies of 98.7%, and high specific capacities of 1044 mAh g(-1) after 100 cycles at 1.0 mA cm(-2), and good cyclic stability. During first cycle discharge process of the S/Ga cathode, the sulfur reduces to Li2S8 and dissolves in the electrolyte, then the liquid metal Ga has an intimate electrical contact with conductive carbon substrates. Electrons are easily transferred to high conductive liquid metal Ga. Due to the electron abundance on Ga surface, it shows an electrocatalytic effect for the conversion of soluble lithium polysulfides (Li2S4-8) to Li2S2/Li2S, thus improving S utilization and cyclic stability. (C) 2020 Elsevier Ltd. All rights reserved.