Dense-Stacking Porous Conjugated Polymer as Reactive-Type Host for High-Performance Lithium Sulfur Batteries

Commercialization of the lithium-sulfur battery is hampered by bottlenecks like low sulfur loading, high cathode porosity, uncontrollable Li2Sx deposition and sluggish kinetics of Li2S activation. Herein, we developed a densely stacked redox-active hexaazatrinaphthylene (HATN) polymer with a surface area of 302 m(2) g(-1) and a very high bulk density of ca. 1.60 g cm(-3). Uniquely, HATN polymer has a similar redox potential window to S, which facilitates the binding of Li2Sx and its transformation chemistry within the bulky polymer host, leading to fast Li2S/S kinetics. The compact polymer/S electrode presents a high sulfur loading of ca. 15 mg(s) cm(-2) (200-mu m thickness) with a low cathode porosity of 41 %. It delivers a high areal capacity of ca. 14 mAh cm(-2) and good cycling stability (200 cycles) at electrolyte-sulfur (E/S) ratio of 5 mu L mg(s)(-1). The assembled pouch cell delivers a cell-level high energy density of 303 Wh kg(-1) and 392 Wh L-1.

Automated summary

The study developed a densely stacked HATN polymer as the electrode material for lithium-sulfur batteries, with high surface area and bulk density to increase sulfur loading and improve kinetics. The electrode demonstrated high energy density and cycling stability.