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

摘要

The nano-crystalline Li_(0.5)La_(0.5)TiO_3 (LLTO) was prepared as an electrolyte material for lithium-ion batteries. The effect of Ag+ ion doping in three different concentrations were investigated: Ag_(0.1)Li_(0.4)La_(0.5)TiO_3, Ag_(0.3)Li_(0.2)La_(0.5)TiO_3, and Ag_(0.5)La_(0.5)TiO_3 along with Li_(0.5)La_(0.5)TiO_3. 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 Ag_(0.5)La_(0.5)TiO_3. 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, Ag_(o.5)La_(0.5)TiO_3 shows maximum conductivity of the order of 10~(-3) S cm~(1).