Mesoporous β-MnO₂/sulfur composite as cathode material for Li-S batteries

Abstract

Highly ordered mesoporous α-MnO2 (HMM) was prepared using KIT-6 templates, and mesoporous β-MnO2/S (HMM/S) composites with four sulfur content were synthesized by thermally treating a mixture of sublimed sulfur and HMM for use as cathode in Li-S batteries. The results of thermal gravimetric analysis, Brunauer-Emmett-Teller measurements, X-ray diffraction, environmental scanning electron microscopy and transmission electron microscopy for samples of HMM and HMM/S material indicate that HMM has a highly ordered pore structure and highly crystalline walls, facilitating electrolyte flooding of these pores within the cathode. The mesopores of HMM contain the majority of the sulfur mass, and effectively suppress the diffusion of polysulfide species into the electrolyte. The thin (nm scale) walls of HMM ensure short diffusion distances for Li+ on intercalation in charge/discharge cycles. Electrochemical experiments show that HMM/S composites with low sulfur content exhibit high discharge capacities and good cycling stability. © 2013 Elsevier Ltd. All rights reserved.