Enhanced cycling performance of nanostructure LiFePO4/C composites with in situ 3D conductive networks for high power Li-ion batteries

Abstract

In this work, reduced nano-sized LiFePO₄ precursor particles were fabricated via a green chemistry approach without the use of any organic solvent or surfactants by accelerating the feeding speed of ferrous sulfate. After carbon coating, a 4 nm thick high graphitic degree carbon layer was deposited uniformly on the surface of reduced nano-sized LiFePO₄ particles and constructed in situ 3D conductive networks among the adjacent LiFePO₄ particles, as a result of an elevated self-catalytic effect of the reduced nano-size LiFePO₄ particles that promoted the formation of the conductive networks. The reduced nano-size LiFePO₄/C particles with in situ 3D conductive networks were shown to have an excellent high rate discharge capacity and long cycle life, delivering a high initial reversible discharge capacity of 163 mA h g⁻¹ at 0.2C and an even high rate discharge capacity of 104 mA h g⁻¹ at 30C. Additionally, a capacity of 101.7 mA h g⁻¹ with a capacity retention of 97% remained after 850 cycles at 30C. This work suggests that the enhanced electrochemical performance of the LiFePO₄/C composite was improved via the combination of the reduced nano-sized and 3D conductive networks, facilitating the electron transfer efficiency and diffusion of lithium ions, especially over an extended cycling performance at a high rate.