A rapid combustion route to synthesize high-performance nanocrystalline cathode materials for Li-ion batteries

Abstract

Nanocrystalline spinel LiMn₂O₄ and layered LiCo_1−xMn_xO₂ (x = 0–0.15) cathode materials were synthesized by a rapid combustion route in combination with an annealing treatment using common filter paper as the template and ethanol as the fuel. The structure, morphology and electrochemical properties of the materials were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), galvanostatic charge–discharge test, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The spinel LiMn₂O₄ annealed at 750 °C shows excellent cycling stability (capacity retention is 92% after 200 cycles), high coulombic efficiency (>99%) and good rate capability. The layered LiCoO₂ shows high initial capacity (168.9 mAh g⁻¹) and good rate capability, but its capacity retention is only 74% after 80 cycles owing to the nanosize effect. After doping a small quantity of Mn (x = 0.05), the cycling performance of the Mn-doped sample was significantly improved compared with that of the pristine LiCoO₂ (capacity retention is 87% after 80 cycles).