A versatile nitrogen-doped carbon coating strategy to improve the electrochemical performance of LiFePO4 cathodes for lithium-ion batteries

Abstract

Abstract To improve the structural stability and electrochemical performance of a LiFePO4 cathode, a nitrogen-doped carbon (N-C) coating strategy is exploited using a simple spray-drying method with dopamine as an N-C coating source. Transmission electron microscopy shows a uniform N-C coating layer on the surface of the LiFePO4 spheres. The introduction of the N-C layer can improve the electrical conductivity and structural stability of the electrode, which results in N-C@LiFePO4 spherical cathode materials with excellent electrochemical properties. The 5% N-C@LiFePO4 spherical composite delivers a specific discharge capacity of 156 mAh g−1, with a capacity retention rate of 86% after 150 cycles at 0.1C. More importantly, because the nitrogen-doped carbon coating can significantly improve the electrochemical performance of the electrode material through excellent electron conductivity, a remarkable rate performance can be achieved by virtue of the thin N-C coated layer, which is superior to that of uncoated LiFePO4. The results from electrochemical impedance spectroscopy further verify that 5% N-C@LiFePO4 has an excellent Li+ conductivity and low charge transfer resistance. This efficient and scalable strategy offers a facile approach to develop high performance LiFePO4-based cathode materials for large-scale lithium-ion storage systems.