A binder-free dry coating process for high sulfur loading cathodes of Li–S batteries: A proof-of-concept

Abstract

A promising candidate for next-generation energy storage is the lithium-sulfur battery (LSB) due to its high capacity and low-cost active material (sulfur). However, the practical application of LSBs is challenged by poor cycling life and low sulfur loading. Herein, a proof-of-concept for manufacturing high load electrodes with a low-cost dry (solvent-free) coating process with a reduced carbon footprint is introduced and investigated. This process is often based on fluoropolymer-based binder additives with health and environmental concerns. Therefore, this study presents the concept of a binder-free dry coating process using sulfur/carbon black (S/CB) composites derived from a straight-forward dispersive mixing process. The electrodes are fabricated by a hot-pressing process, taking advantage of sulfur melting into a carbon matrix. To determine the process-structure-property relationships of the resulting powders, electrodes and cells, a novel structure determination by thermogravimetric analysis was used. Mixing time turns out to be an important factor, which has a significant effect on the electrode performance. The cells assembled with electrodes (⁓4.5 mgS cm−2) made from optimized powder mixtures showed a high specific capacity of about 800 mAh gS−1, and a relatively improved C-rate capability.