A team from the Ningbo Institute of Material Technology & Engineering, Chinese Academy of Sciences has developed a graphene-modified LiFePO4 composite as a Li-ion battery cathode material with excellent high-rate capability and cycling stability. They report on the material in a paper in the RSC Journal of Materials Chemistry.
The composite cathode material delivers a capacity of 70 mAh g-1 at 60C discharge rate and shows a capacity decay rate of <15% when cycled under 10C charging and 20C discharging for 1,000 times.
The composite was prepared with LiFePO4 nanoparticles and graphene oxide nanosheets by spray-drying and annealing processes. The LiFePO4 primary nanoparticles embedded in micro-sized spherical secondary particles were wrapped homogeneously and loosely with a graphene 3D network. Such a special nanostructure facilitated electron migration throughout the secondary particles, while the presence of abundant voids between the LiFePO4 nanoparticles and graphene sheets was beneficial for Li+ diffusion, they said.
Resources
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Xufeng Zhou, Feng Wang, Yimei Zhu and Zhaoping Liu (2011) Graphene modified LiFePO4 cathode materials for high power lithium ion batteries. J. Mater. Chem. Advance Article doi: 10.1039/C0JM03287E