Accelerating the Lithium Storage Kinetics of Organosulfur Copolymers with Pyridine/Selenium Dual-Doping for Lithium-Organosulfur Battery

Abstract

Lithium-organosulfur batteries have positioned themselves at the forefront of energy storage due to high theoretical specific capacity, solid–solid reaction mechanism. In order to further decrease the shuttle effect and improve reaction kinetics, a copolymer cathode (PTSC) with short-chain sulfur (R-S₄-R) is first synthesized using propylene coordinated with carbon nanotube (CNT). Subsequently, pyridine and selenium atoms with well electroconductivity are introduced to synthesize the copolymer cathode (PTDSC, PTDSSeC). The lone pair electrons on nitrogen atoms within pyridyl groups establish strong Lewis acid–base interactions with lithium polysulfides, effectively anchoring active species and mitigating capacity fade; concurrently, the conjugated structure of pyridine rings optimizes electron transfer pathways to enhance reaction kinetics. Selenium, leveraging its lower electronegativity, redistributes charge density to reduce SS bond dissociation energy, facilitating reversible polysulfide conversion. The CNTs provide a 3D conductive scaffold and spatially confine polysulfides within the cathode. This synergy achieves quick kinetics of lithium polysulfides redox. Electrochemical result confirms that the copolymer cathode exhibits superior rate stability and capacity retention. Specifically, the PTDSSeC cathode maintains 76.4% of its reversible specific capacity after 500 cycles at a current density of 0.5 A g⁻¹. This work demonstrates the synergistic optimization of “low shuttle-high activity-fast conduction” through the integration of short-chain sulfur, pyridine functional groups, and selenium atoms.