Potentiostatic lithium plating as a fast method for electrolyte evaluation in lithium metal batteries

Abstract

One of the most crucial factors to enable metallic lithium anodes is having an electrolyte that allows stable and safe battery cycling, however, the commonly used carbonate electrolytes typically perform poorly, highlighting the need for the development of new electrolyte compositions. Evaluating potential electrolyte candidates is typically a lengthy procedure that does need time-consuming long-term cycling experiments. To speed this process up, we have investigated potentiostatic lithium plating, inspired from hydrogen-pumping performed for fuel cell performance evaluation, as a potential method for fast electrolyte suitability investigation. First, scanning electron microscopy was used to establish a link between lithium surface coverage and measured current response in a model carbonate electrolyte. Afterwards, a selection of carbonate and ether electrolytes was used for validation of our testing procedure, showing that individual, characteristic patterns can be distinguished. Apart from giving an insight into Li transport in each electrolyte, a correlation to physical electrolyte properties can be found. Consequently, our findings may be a first step towards using potentiostatic plating as a fast, easy and high-throughput method to investigate suitability of new electrolyte formulations for lithium metal batteries and beyond.