Three-dimensionally ordered hierarchically porous polypyrrole loading sulfur as high-performance cathode for lithium/sulfur batteries

A novel three-dimensionally (3D) ordered hierarchically porous polypyrrole (3DOHPPy) is successfully synthesized via a simple chemical polymerization method by using silica colloidal crystals as templates. The 3DOHPPy possesses a large BET specific surface area (118.5 m 2  g −1 ), 3D ordered interconnected macropores (240 nm) and mesopores (2–3 nm) on the macropore walls. The sulfur/3DOHPPy (S/3DOHPPy) composite is prepared by a solution-diffusion route followed by low-temperature heat treatment and studied as a cathode material for the lithium/sulfur (Li/S) battery. The resulting S/3DOHPPy cathode shows a high specific discharge capacity of 751 mAh g −1 even after 100 cycles at 0.1 C and great rate capability. The superior electrochemical property of the S/3DOHPPy composite is ascribed to the unique hierarchical structure of 3DOHPPy with ordered interconnected macropores that benefit enhanced mass transfer and the small mesopores on the macropore walls that can immobilize the sulfur and polysulfides produced during the discharge/charge processes.