Surface modification of LiFePO4 cathode enabled by highly Li+ mobility wrapping layer towards high energy and power density

Abstract

Surface-modified cathode materials have been developed to achieve high-performance lithium secondary batteries with higher capacity, rate capability, and longer cycle performance than bulk active materials. In this study, a new surface-modified active material was explored through a low-temperature -solution wrapping method (LiFePO@LiSiO composite). In addition, high Li-ion and electronic conductivity materials with amorphous nanostructures, in which the bulk LiFePO nanoparticles were covered with a LiSiO layer, were demonstrated. In lithium-ion batteries, the LiFePO@LiSiO composite demonstrated enhanced charge transfer kinetics, which lowered the interfacial resistance between electrode and electrolyte and resulted in enhanced electrochemical performance when compared to that of bulk LiFePO. Furthermore, LiSiO is introduced as a surface stabilizer and effective Li-ion conductor to avoid side reactions and prevent the dissolution of active materials into the electrolyte. The designed cathode delivers a high specific discharge capacity of 171.8 mAh g at 0.1 C with 99.76 % capacity retention after 150 cycles and a high capacity of 121.2 mAh g at 10 C. Moreover, Li-ion full batteries employing LiFePO@LiSiO and graphite displayed a high specific energy density of 416.078 Wh kg at a power density of 69.34 W kg at 5 C. In summary, this paper reports a new strategy based on low-temperature solution phase wrapping materials for developing active materials for high energy-power density energy storage devices.