Elemental analysis is a challenge for the development of High Throughput Experimentation (HTE) on thin film materials, and an even greater one when it comes to screening lithium-containing battery materials. In this regard, Laser-Induced Breakdown Spectroscopy has been evaluated here for the quantitative analysis of lithium in libraries of Li2.3PO3.65 amorphous solid electrolyte films. The LIBS analysis of multiple samples with the same composition, but with thicknesses ranging from 50 to 700 nm, has revealed a linear trend in the intensity ratio of the Li I 610.35 nm and P I 214.91 nm emission lines, opening the way to rapid quantitative analysis of material libraries. The sensitivity of the technique finally allowed the detection of the Li I 670.79 nm emission line for film thicknesses down to 4 nm, corresponding to 0.2% of the ablated volume, or about 0.15 pg of Li