Investigations on pure and Ag doped lithium lanthanum titanate (LLTO) nanocrystalline ceramic electrolytes for rechargeable lithium-ion batteries

The nano-crystalline Li0.5La0.5TiO3 (LLTO) was prepared as an electrolyte material for lithium-ion batteries. The effect of Ag+ ion doping in three different concentrations were investigated: Ag0.1Li0.4La0.5TiO3, Ag0.3Li0.2La0.5TiO3, and Ag0.5La0.5TiO3 along with Li0.5La0.5TiO3. The prepared pure and Ag+ doped LLTO were subjected for structural, morphological, electrical and optical characterizations. The cubic superlattice structure of LLTO nano-powder was altered due to the Ag+ substitution tending towards a tetragonal phase. Increasing Ag+ substitution a complete tetragonal phase occurs in Ag0.5La0.5TiO3. The average particle size of the prepared ceramic electrolyte ranged between 80 nm and 120 nm. The photoluminescence study reveals that the LLTO and Ag doped LLTO gives a blue emission peak. The size effect on grain and grain boundary resistance was observed and reported. With Ag+ substitution, the conductivity got decreased due to the impedance caused by Ag+ ions in the conducting path of Li+ ion. Among all the samples, Ag0.5La0.5TiO3 shows maximum conductivity of the order of 10−3 S cm−1.