FTO Darkening Rate as a Qualitative, High-Throughput Mapping Method for Screening Li-Ionic Conduction in Thin Solid Electrolytes

Abstract

We present a high-throughput (combinatorial) method to screen thin ceramic films as Li-ion conductors by mapping an optical effect of Li-ion conduction. The method, while qualitative, is fast and simple to implement, provides a planar (XY) map of Li-ion conductivity through different parts of the film. The effect, FTO darkening, is an optoelectrochemical one that relies on darkening of the FTO (F-doped tin oxide) substrate, onto which the investigated film is deposited. The rate of color change of the FTO reflects the rate of Li-ion migration through the film.The method is validated by testing two model systems, a Li− La−S−O film with uniform composition and varying thickness, and a Li−La−P−O film with varying thickness and lateral composition. The darkening rate, obtained from optical transmission, correlates linearly with inverse film thickness. The darkening rate map can be compared with a resistance map obtained by impedance measurements, showing that only Li conduction is measured. We discuss the conditions required to distinguish between areas with pure ion conductivity and those with mixed conductivity, the reversibility of the darkening effect and artifacts.

High‐Throughput Experimentation and Computational Freeway Lanes for Accelerated Battery Electrolyte and Interface Development Research

“…Besides, Tirosh et al demonstrated a HT mapping method based on the F‐doped tin oxide darkening effect for screening the ionic conductivity in solid state electrolytes. [ 121 ] Each measurement requires only 5 min which is 100× faster compared with the traditional EIS method. However, the distinguishment between grain and bulk lithium ion conductivity cannot be realized.…”

Between Liquid and All Solid: A Prospect on Electrolyte Future in Lithium‐Ion Batteries for Electric Vehicles

“…We live in an era where advanced algorithms together with powerful hardware are able to predict the ionic transport of ceramic electrolytes. [137] The ability to narrow the overwhelming number of candidate materials [138,139] by computational means, such as the Materials Project, [137] constitutes a considerable advantage over the polymer or liquid electrolyte families. The high energy density of ion-conducting ceramics together with a clear understanding of the manufacturing process marks them as very promising electrolytes of the future.…”

Accelerated screening of Cu–Ga–Fe oxide semiconductors by combinatorial spray deposition and high-throughput analysis

“…8 Furthermore, it can be easily implemented as combinatorial deposition method for (1) thickness gradients by adjusting the covered area of multiple spray cycles [9][10][11][12][13][14][15] and (2) composition gradients a Energy Conversion and Hydrogen, Center for Energy, AIT Austrian Institute of by capitalizing the lateral spread of the spray cone and overlapping different precursor solutions consecutively 16 or simultanously. [17][18][19] Directly mixing multiple solutions during a laterally resolved coating process has already been reported. 20 In this contribution we synthesize combinatorial films with two-dimensional composition gradients of metal oxides.…”