Effect of the Iron Doping on the Crystal Structure and Electrochemical Performances of LiCoPO4

Current research in lithium-ion battery field focuses on the improvement of energy density and power performances. One way to increase the battery energy is the use of high voltage cathode materials with a large charge capacity and cycling capability. The LiCoPO₄ olivine is an interesting candidate as high-voltage cathode for lithium cells due to its high working potential cells (4.8 V vs. Li/Li⁺), still within the working limits of the carbonate-based liquid electrolytes, its flat voltage profile and a theoretical capacity of about 167 mAh g^-1. However the poor electronic conductivity and the low Li-ion diffusion coefficient limit its practical application [1].

Herein we present our recent results about the study of the synthesis of lithium cobalt phosphate materials and the effect of the iron doping on its structural features and electrochemical properties in lithium cell. In particular X-ray diffraction experiments have been carried out at the MCX beamline in the ELETTRA facility in order to elucidate the role played by iron doping on the lattice structure and local ordering of the cation sublattice. Furthermore a careful analysis of the performances in lithium cells have been carried out by comparing materials prepared in different experimental conditions with and without iron doping, in order to decouple the concurrent effects that drive the ability of this material to reversibly cycle lithium (e.g. particle size, lattice disorder, iron doping).

[1] S.Brutti, S.Panero, Recent Advances in the Development of LiCoPO4 as High Voltage Cathode Material for Li-Ion Batteries in “Nanotechnology for Sustainable Energy”, ACS Symposium Series, Vol. 1140, Chapter 4, pp 67–99