Leveraging Lithium-Bond Chemistry in a Tailored Electrolyte to Control Sulfur and Lithium Evolution in Li-S Batteries.

Abstract

Rational regulation of lithium polysulfide reaction kinetics, coupled with strategies for stabilizing the Li anode, constitutes a cornerstone for lithium-sulfur (Li-S) chemistry. Herein, we propose phthalocyanine (Pc) as a homogeneously dispersed promoter in the electrolyte for Li-S batteries, based on its N₈-cavity planar rigid structure featuring an electron-rich macrocyclic core. Under the optimized concentration of Pc in electrolyte, we reveal that the Li─N coordination bonds between Li₂S₈ and Pc in the catholyte of Li-S batteries, which significantly contribute to the catalytic conversion of sulfur species. Meanwhile, Pc molecules in the anolyte preferentially adsorb onto the Li anode surface, forming a dense molecular layer by virtue of Li─N bonding, which effectively enhances interfacial desolvation kinetics and thereby promotes uniform Li deposition. Enabled by the promoted Li-S chemistry through Li─N bonds, the battery with Pc enabler achieves a low decay rate of 0.0479% per cycle after 600 cycles at 1C. More remarkably, 1.07 Ah pouch cells deliver a high energy density of 325.5 Wh kg^-1, serving as a compelling design strategy for leveraging sustainable Li─N bond chemistry to achieve high-rate and long-life Li-S battery technology.