Yingke Zhou

Nitrogen-doped graphene guided formation of monodisperse microspheres of LiFePO4 nanoplates as the positive electrode material of lithium-ion batteries

Three-dimensional porous composite microspheres of LiFePO4 and nitrogen-doped graphene have been synthesized by a solvothermal process coupled with subsequent calcination. The morphology and microstructure of the composites were investigated by scanning electron microscopy, X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. The electrochemical properties were evaluated by constant current charge/discharge tests, cyclic voltammetry and electrochemical impedance spectroscopy. The unique porous structure of the microspheres was constructed by the assembly of nitrogen-doped graphene and LiFePO4 nanoplates and can remarkably enlarge the electrode/electrolyte interface area, facilitate the electron transfer process, shorten the ionic diffusion path and accelerate the ionic transport throughout the electrode. In electrochemical measurements of the specific charge capacity, rate capability and cycling stability, the obtained porous composite microsphere materials offer remarkably promising results for applications in high-performance lithium-ion power batteries.

Freeze-drying of “pearl milk tea”: A general strategy for controllable synthesis of porous materials

Porous materials have been widely used in many fields, but the large-scale synthesis of materials with controlled pore sizes, pore volumes, and wall thicknesses remains a considerable challenge. Thus, the controllable synthesis of porous materials is of key general importance. Herein, we demonstrate the “pearl milk tea” freeze-drying method to form porous materials with controllable pore characteristics, which is realized by rapidly freezing the uniformly distributed template-containing precursor solution, followed by freeze-drying and suitable calcination. This general and convenient method has been successfully applied to synthesize various porous phosphate and oxide materials using different templates. The method is promising for the development of tunable porous materials for numerous applications of energy, environment, and catalysis, etc.