Mitigation of grain boundary resistance in La2/3-xLi3xTiO3 perovskite as an electrolyte for solid-state Li-ion batteries

• Published in: Journal of materials science Vol. 56; no. 3; pp. 2435 - 2450
• Main Authors: Polczyk, Tomasz, Zając, Wojciech, Ziąbka, Magdalena, Świerczek, Konrad
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.01.2021; Springer Nature B.V
• Subjects: Additives; Characterization and Evaluation of Materials; Chemical composition; Chemistry and Materials Science; Classical Mechanics; Cobalt; Conduction; Copper; Crystallography and Scattering Methods; Electrical resistivity; Energy Materials; Grain boundaries; Lithium borates; Lithium fluoride; Lithium-ion batteries; Materials Science; Molten salt electrolytes; Perovskites; Polymer Sciences; Reagents; Rechargeable batteries; Sintering; Solid electrolytes; Solid Mechanics; Space charge
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-020-05342-7

In this work, we report that modification of the chemical composition of grain boundaries of La 2/3-x Li 3x TiO 3 double perovskite, one of the most promising Li-ion conducting solid electrolytes, can be a convenient and versatile way of controlling the space charge potential, leading to a mitigated electrical resistance of the grain boundaries. Two groups of additives are investigated: lithium-enriching agents (Li 3 BO 3 , LiF) and 3 d metal ions (Co 2+ , Cu 2+ ), both expected to reduce the Schottky barrier. It is observed that Li-containing additives work effectively at a higher sintering temperature of 1250 °C. Regarding copper, it shows a much stronger positive impact at lower temperature, 1150 °C, while the addition of cobalt is always detrimental. Despite overall complex behavior, it is documented that the decreased space charge potential plays a more important role in the improvement of lithium conduction than the thickness of the grain boundaries. Among the proposed additives, modification of La 2/3-x Li 3x TiO 3 by 2 mol.% Cu 2+ results in the space charge potential reduction by 32 mV in relation to the reference sample, and the grain boundary specific conductivity increase by 80%, as measured at 30 °C. Introduced additive allows to obtain a similar effect on the conductivity as elevating the sintering temperature, which can facilitate manufacturing procedure. Graphic abstract