The improved performance of spinel LiMn₂O₄ cathode with micro-nanostructured sphere-interconnected-tube morphology and surface orientation at extreme conditions for lithium-ion batteries

Recently, spinel-type LiMn₂O₄ (LMO) cathode has attracted great attention to mitigate manganese dissolution especially at elevated temperature. In this work, LMO with surface specific facets and different morphologies are successfully controlled synthesized via a facile solvothermal-lithiation method. It suggests that microspheres, micro-tubes and hybrid sphere-interconnected-tube microstructures with different surface lattice orientation using urea, oxalic acid and mixture of urea and oxalic acid as precipitants at solvothermal stage, respectively. Specifically, LMO microspheres (LMO-MS) display (111) facets and the micro-tubular LMO materials (LMO-MT) exhibit the high index lattice (311). It is more interesting is that hybrid sphere-interconnected-tube microstructures (LMO-MST) are clearly observed the densest (111) facets at the micro-spherical surface and a new (111) plane appearance on the surface of microtubes. LMO-MST demonstrates excellent cycling performance (84.3 % capacity retention after 1000 cycles at 10 C) and superior rate capability up to 10 C (124.2 mAh g⁻¹ at 10 C). The electrochemical performances of LMO-MST cathodes are also investigated at elevated (55°C) and lower (-5°C) temperatures, under which LMO-MST still maintains optimal cycling stability. The superior electrochemical performance of LMO-MST cathodes can be attributed to the unique sphere-bridged-tube seamless outer structure and the preferentially exposed stable facets on the crystal surface.