Sulfur-Infiltrated Three-Dimensionally Ordered Mesoporous Polypyrrole Cathode for High-Performance Lithium-Sulfur Battery

A novel three-dimensionally (3D) ordered mesoporous polypyrrole (OMPPy) is successfully synthesized through a facile chemical polymerization using silica nanosphere arrays as hard templates. The resulting OMPPy possesses a large BET surface area (270.9 m² g⁻¹), 3D interconnected large mesopores (∼32 nm), and small mesopores (2-4 nm) on the large mesopore walls. The OMPPy is then applied as a host to form a kind of sulfur/OMPPy (S/OMPPy) composite cathode through a solution method followed by a heat-treatment process. Electrochemical test results show that the developed S/OMPPy cathode containing 51.1 wt% sulfur is able to deliver a high and stable specific discharge capacity of 908 mAh g⁻¹ at 0.1C after 100 cycles. At higher discharge rates of 1C, the S/OMPPy exhibits a discharge capacity of 673.7 mAh g⁻¹ after 100 cycles and 462.2 mAh g⁻¹ after 300 cycles. The exceptional electrochemical performance of the S/OMPPy is attributed to the large surface area and the commendable pore size distribution of OMPPy for trapping polysulfides as well as the ordered large mesopores for excellent electrolyte accessibility and fast Li-ion transport.