DFT-driven design of efficient dual-atom electrocatalysts for lithium-sulfur batteries: Fe dimers supported on phthalocyanine

Abstract

Lithium-sulfur (Li-S) batteries have garnered widespread attention and research due to their high theoretical capacity and energy density. However, their commercialization is hindered by several issues, including low electrical conductivity of the sulfur electrode, the polysulfide shuttle effect, and slow charge–discharge kinetics. Double-atom transition metal phthalocyanines (M₂-Pc), which are large conjugated compounds with M₂-N₁₂ rings, have potential application value in electrochemical catalysis due to their unique electronic structures and metal coordination properties. Through a five-step screening strategy, the study investigated the catalytic activity of a series of M₂-Pc (M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) towards S₈/LiPSs. The results show that Fe₂-Pc exhibits the best catalytic activity, attributed to its low Gibbs free energy (0.88 eV) in the rate-limiting step of the discharge reaction and its low decomposition energy barrier (0.72 eV) of Li₂S during the charge reaction. Additionally, the integral of crystal orbital Hamiltonian population (ICOHP) can serve as a descriptor for the catalytic activity related to the decomposition energy barrier of Li₂S during the charging process. This provides theoretical guidance for the design of Li-S battery cathode materials and further experimental work.