Advancing Sulfur–Carbon Composite Production: Industrial and Lab-Scale Infiltration Techniques for Metal–Sulfur Batteries

Abstract

In a metal-sulfur battery, the cathode consists of a composite material made from activated carbon and sulfur, which acts as the electrochemically active component. To fill the pores of the activated carbon with sulfur, both melt infiltration and gas infiltration techniques are employed. [1-3] However, the entire procedure, involving heating and cooling phases, is highly time- and energy-consuming. Moreover, the currently established methods allow only very small sample quantities to be processed in batch mode. The cost associated with processing larger volumes is prohibitively high, rendering these methods economically unviable.

To optimize the production of sulfur-carbon composites, infiltration techniques that increase material throughput while reducing processing time and energy consumption are essential. For this purpose, various infiltration methods have been tested and their performance thoroughly analyzed.

Sulfur is introduced into microporous carbon using different infiltration approaches based on both melt and gas infiltration. Continuous industrial-scale processes and rapid batch methods are evaluated and compared against laboratory-scale techniques.

The infiltration experiments were conducted using a carbon aerogel with a micropore volume ranging from 0.27 to 0.45 cm³/g. The findings demonstrate that the highest sulfur loadings were achieved through gas, extruder and melt infiltrations, with the sulfur predominantly present in the micropores. The composites produced with gas [4], spray-coating technique [5], and extruder infiltrations [3] exhibit good cycle stability and high discharge capacity. In contrast, open gas infiltration, microwave infiltration and solvent infiltration resulted in lower sulfur loading and inadequate performance in the cell. The results are summarized in our poster.

Depending on the specific battery requirements, the infiltration technique can be chosen between complex, non-scalable methods with outstanding performance and more economically efficient methods offering moderate performance.