In this work, thick films of Perovskite La 0.57 Li 0.33 TiO 3 (LLTO) and Li-NASICON Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 (LATP) Li-conductors have been prepared by tape casting and their microstructure and homogeneity assessed by SEM and confocal Raman spectroscopy. Electrical properties of thick films have been investigated by Impedance spectroscopy. In particular, bulk, grain-boundary and electrode contributions to conductivity have been differentiated as a function of frequency. However, modifications on the grainboundary chemistry affects considerably ion conductivity of films. The confocal Raman spectroscopy results allowed the observation of the resulting phases particles connectivity in thick films and a better understanding of ionic conductivity results in relation with the samples heterogeneity. In LLTO films, the reactivity of the film particles against water leads to formation of hydroxyl groups that decreases the Li mobility at the particles surface after sintering. In LTAP films the formation of a high conducting grain-boundary phase leads to improve total conductivity values making thick films promising candidates for application in all solid state Li secondary batteries.

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Solid-state batteries are the next step on the way of developing lithium power sources because of combination of high energy density (up to 500 W/kg and 1000 W/l) and better safety. Yet their major drawbacks are high interfacial resistance and poor interface contacts between the solid electrolyte and active material. One of possible solutions to the problem is to produce an active material whose particles would be coated with a solid electrolyte. Titanium-aluminum-lithium phosphate Li 1,3 Al 0.3 Ti 1.7 (PO 4 ) 3 (LATP) is a solid electrolyte which exhibits one of the highest conductivity (∼10 −3 −10 −5 S/cm) and is chemically stable. Therefore, the aim of this study was synthesis and investigation of composite cathodes based on cathode materials LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NMC) with protective interface layer of solid state electrolyte LATP. The influence of the amount of LATP on the electrochemical properties of NMC was investigated. The composite NMC cathode material with protective interface layer of solid state electrolyte with content of LATP 1% exhibited high capacity (ca. 150 mAh g −1 ) and good cycle performance with a high charge cutoff voltage up to 4.5 V.

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