Biomimetic Synthesis of Ear-of-wheat-shaped Manganese Oxide Nanoparticles on Carbon Nanotubes for High-capacity Lithium Storage

Manganese oxide (Mn₃O₄) is of great potential for lithium storage based on conversion reactions, but its application in rechargeable lithium batteries is severely hindered by the low electric conductivity and large volume variation during lithiation/delithiation. Herein, a biomimetic ear-of-wheat-like nanocomposite of ultrafine Mn₃O₄ nanoparticles (MONPs) and multi-walled carbon nanotubes (MWCNTs) is prepared using a facile solvothermal method. The tightly packed MONP “cereal-grains” are directly grown and uniformly interspersed on the outer surface of skeleton MWCNT “central stems.” The ultrafine MONPs are favorable to lithium incorporation/extraction while the interconnected MWCNT skeletons provide a highly conducting network for electron transportation. Consequently, a high reversible capacity of 810 mA h g⁻¹ is obtained at the current density of 40 mA g⁻¹. After 50 cycles at 160 mA g⁻¹, the nanocomposite still delivers a capacity up to 796 mA h g⁻¹, which is higher than twice of that of pure Mn₃O₄ nanopowders. The unique nanostructure and the facile biomimetic method can be widely extended to design and explore various high-performance energy materials for lithium/sodium ion batteries and fuel cells.