Microwave-assisted synthesis of a manganese metal–organic framework and its transformation to porous MnO/carbon nanocomposite utilized as a shuttle suppressing layer in lithium–sulfur batteries

Abstract

In this work, the microwave-assisted synthesis of manganese metal–organic framework (MOF) material is presented. Synthesis procedure is based on a microwave-assisted solvothermal reaction of manganese(III) acetylacetonate with biphenyl-4,4′-dicarboxylic acid (Bpdc) in N,N′-dimethylformamide at the temperature of 160 °C. The obtained Mn-based metal–organic framework, labeled as Mn-Bpdc, was used as a precursor for the preparation of a porous MnO/carbon nanocomposite, which was obtained via thermal transformation in a nitrogen atmosphere at 700 °C. It was found that this approach provides an effective and simple preparation pathway for porous carbon decorated with homogeneously embedded manganese(II) oxide nanoparticles. Both Mn-Bpdc and MnO/C nanocomposite materials were characterized by a variety of physicochemical methods. The prepared MnO/C nanocomposite material was deposited on a cathode surface of lithium-sulfur batteries and utilized as a shuttle suppressing layer. This electrode structure immobilizes polysulfides inside the cathode and improves the stability during cycling. The electrode with MnO/C nanocomposite shuttle suppressing layer maintains high stability during cycling in comparison with a standard electrode. The electrode with MnO/C composite layer exhibits 84.8% capacity retention after 50 cycles at different C-rates compared to 76.2% obtained for the standard electrode. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.