Energy & Fuels, Vol.35, No.4, 3417-3425, 2021
Preparation of a Spherical MnO2 Intermediate by an Organic Template Method and Its Effect on the Electrochemical Performance of Lithium-Rich Manganese-Based Materials
Polyvinylpyrrolidone (PVP) and ethylene glycol (EG) are used as the template agents to prepare an assisted spherical MnO2 intermediate, which is used to prepare lithium-rich manganese-based materials with a loose structure. The structure and morphology of the obtained samples are characterized by X-ray diffraction, scanning electron microscopy, particle size analysis, and N-2 adsorption. Electrochemical tests, including cyclic voltammetry, electrochemical impedance, rate and life performance, and galvanostatic charge and discharge, are used to study their electrochemical performance. The results show that the addition of PVP and EG does not change the crystal structure of the obtained material, retaining the alpha-NaFeO2 structure of lithium-rich manganese-based materials. The secondary particles of the obtained material have a loose structure. The primary particles have an obvious uniform particle size distribution with small particle size, and there is no obvious agglomeration and accumulation between the primary particles. The initial discharge specific capacity and coulomb efficiency of the material prepared by the modified MnO2 intermediate are 283 mA h g(-1) and 85.5% (at 0.1 C), respectively, which are significantly better than those of the material prepared by ordinary MnO2 (222 mA h g(-1) and 76.3%, respectively). Its high rate discharge performance and the cycle capacity retention rate are 110 mA h g(-1) at 10 C and 90.7% after 50 cycles, respectively.