Ferromagnetic two-dimensional Fe3GaTe2 and Ni-doped Fe3GaTe2 as electrocatalysts for lithium–sulfur batteries: a first-principles study

Abstract

Li–S batteries are regarded as next-generation energy storage solutions due to their exceptional theoretical capacity. However, their practical application is hindered by the shuttling effects of lithium polysulfides (LiPSs) and the sluggish decomposition of Li₂S. Addressing these challenges necessitates the development of effective catalysts that can accelerate the conversion of LiPSs and enhance the performance of Li–S batteries. In this study, we investigated the electrocatalytic activity of two-dimensional ferromagnetic Fe₃GaTe₂ and Ni-doped Fe₃GaTe₂ in Li–S batteries using first-principles calculations. Our findings indicate that these materials exhibit optimal binding strengths (ranging from 1.03 to 1.45 eV) with long-chain LiPSs, effectively preventing their dissolution into the electrolyte. Furthermore, we demonstrate remarkable catalytic activity during the sulfur redox reaction (SRR), with the ΔG of only 0.54 eV for Ni-doped Fe₃GaTe₂. The reduced energy barrier induced by Fe₃GaTe₂ and Ni-doped Fe₃GaTe₂ significantly accelerates the charge/discharge kinetics of Li–S batteries. Furthermore, the Ni-doped Fe₃GaTe₂ demonstrates an increase in binding energy, alongside a decrease in Gibbs free energy in the rate-determining step and activation energy barrier, collectively enhancing its catalytic performance. We conducted an in-depth analysis from the perspectives of magnetic moment and p-band theory. This theoretical work contributes to a better understanding of the application of ferromagnetic materials in the Li–S battery domain, paving the way for advanced high-efficiency energy storage solutions.