Microwave-assisted synthesis and surface decoration of LiFePO4 hexagonal nanoplates for lithium-ion batteries with excellent electrochemical performance

Microwave-assisted synthesis of electrode materials for lithium-ion batteries has drawn extensive attention owing to the unique microwave dielectric heating. In this work, olivine LiFePO4 hexagonal nanoplates, with a short b-axis, were successfully synthesized using a single-mode microwave-assisted hydrothermal system at 160 A degrees C just in 20 min. Microwave irradiation can lower the synthesis temperature and shorten the synthesis time dramatically. The growth process of LiFePO4 hexagonal nanoplates with microwave irradiation time was investigated. The role of electromagnetic field in the formation and the quality of the resulting LiFePO4 were explored. In order to enhance the electrochemical properties of LiFePO4 hexagonal nanoplates, LiFePO4/C and LiFePO4/rGO have been obtained through surface decoration of LiFePO4 nanoplates by ex situ carbon coating and in situ reduced graphene oxide (rGO) coating. The electrochemical analysis demonstrated that LiFePO4/rGO had more excellent electrochemical performance; the initial discharge capacity at 0.1 C was up to 167.2 mAh g(-1) which was very close to the theoretical value (170 mAh g(-1)). This is because the in situ coating can achieve a complete coating of the surface and rGO has a higher electrical conductivity. The rGO layer can boost the transport speed of the lithium ions and electrons, and reduce the charge transfer resistance of Li ion insertion/extraction. Furthermore, the unique structure of the nanoplates with a short b-axis is favored to shorten the migration of Li+ ion.