Three-dimensional nanohybrids of Mn3O4/ordered mesoporous carbons for high performance anode materials for lithium-ion batteries

Abstract

We developed a facile one-step route to three-dimensional hybrids with Mn₃O₄ nanoparticles well and homogeneously embedded within ordered mesoporous carbon (OMC) for lithium ion battery applications. The Mn₃O₄/OMC hybrids with good rate capability and cycling stability display a high specific capacity up to 802 mA h g⁻¹, and a high coulombic efficiency of up to 99.2% even after 50 cycles at a high current density of 100 mA g⁻¹. This value is 1.6 times higher than the discharge capacity of 512 mA h g⁻¹ for pure ordered OMC materials, and more than 5.4 times higher than the discharge value of 148 mA h g⁻¹ for pure Mn₃O₄ nanoparticles. The enhanced capacity and cycling performance of the Mn₃O₄/OMC hybrids could be attributed to their unique robust three-dimensional composite structure and the synergistic effects between the Mn₃O₄ nanoparticles and OMC. The ordered mesostructured channels of Mn₃O₄/OMC hybrids are expected to buffer well against the local volume change during the Li uptake/removal reactions and thus to enhance the structural stability. The OMC matrix wall with a thickness of <10 nm greatly reduces the solid-state transport length for Li diffusion, and the hierarchical ordered mesoporosity facilitates the liquid electrolyte diffusion into the bulk of the electrode material and hence provides fast conductive ion transport channels for the conductive Li⁺ ions. The improved cycling performance can also be mainly attributed to good electrical contact between the Mn₃O₄ and OMC in the three-dimensional nanocomposites during phase transformation of Mn₃O₄ upon lithiation/delithiation that usually leads to capacity fading. This facile strategy can be extended to fabricate other ordered mesoporous carbon-encapsulated metal oxides.