Self-Discharge Phenomena in LiCoPO4 Electrodes

Polyanion-type materials, like lithium iron phosphate, are one of the recent great success in the research field of applied electrochemistry. Within this family, LiFePO4 (LFP) is a now mature material and its properties have been largely optimized thus opening the door to its commercial exploitation as cathode material in lithium-ion cells for power tools. In recent years the attention of the scientific community is focusing the great advantage of the substitution in the LFP lattice of Fe with Mn, Co or Ni. In fact the Mn3+/Mn2+, Co3+/Co2+ and Ni3+/Ni2+ couples show increasing redox potentials, all higher than the Fe3+/Fe2+, thus opening the door to large improvements in the energy performances. Among them LiCoPO4(LCP) is the best compromise: it shows in lithium cells an higher working potential compared to LFP, still within the working limits of the carbonate-based liquid electrolytes. However many fundamental aspects of the LCP properties and reaction mechanisms in lithium cells are not completely understood. Owing to this, large room for improvements in the performances in Li-cells of LCP is expected by assessing the synthesis route, the coatings, the doping/substitution and the electrolyte additives. ... ...