The microwave-assisted spray drying synthesis: Application to the of LiFePO4/C cathode material for Li-ion batteries

LiFePO₄/C (LFP/C) composite is one of the most viable and promising cathode material for Li-ion batteries. Currently, a spray-drying technique is considered as a critical process for improving the compact density of LFP/C though the preparation of spherical agglomerated particles. Herein, we have developed a novel microwave-assisted spray-drying (MASD) technique to spherolize the LFP/C particles in an efficient and economical way. In contrast to the conventional spray-drying (CSD), in which the heat is transferred to droplets from hot gas or air, in MASD the microwave radiation acts as the energy source and interacts directly with the whole volume of the droplets thus reducing the thermal gradients and producing the uniform heating throughout the particles. The LFP/C material obtained via the MASD approach coupled with carbothermal reduction exhibits micro-spherical agglomerates and uniform conductive carbon layer on the particle surface. The MASD-treated cathode material demonstrates reversible capacity up to ∼162 mAh/g, good cycling stability in both half- and full-cell configurations, and high tap density of 1.6 g/cm³. Finally, the developed MASD technique is estimated to be at least ∼1.4 times more energy efficient than CSD that might be transferred to measurable energy saving in mass production of LFP-based cathode materials.