Influence of Primary Particle Morphology and Hydrophilicity of Carbon Matrix on Electrode Coating Quality and Performance of Practical High-Energy-Density Li–S Batteries

Abstract

Li–S batteries have attracted attention as the next-generation secondary batteries. While substantial progress is made in understanding Li–S chemistry at a fundamental level, only a limited number of studies are dedicated to achieving high energy density at the practical pouch cell level. The challenge lies in attaining high-energy-density Li–S batteries under harsh conditions, which involve a minimal amount of electrolyte and a relatively high areal S-loading cathode. This discrepancy creates a substantial gap between fundamental material research and comprehensive cell-level investigations. In this study, it is investigated how the morphology and properties of two carbon materials, namely Ketjen black (KB) and mesoporous carbon nano-dendrites (MCND), influence the composite cathode architecture and determine the performance of Li–S batteries. Unlike KB, MCND allows for a higher sulfur-loading cathode without evident cracks in the composite cathode. This achievement can be attributed to the high porosity, excellent wettability, and high conductivity exhibited during an identical electrode preparation procedure. Furthermore, large-format Li–S pouch cells incorporating MCND/S cathodes are successfully fabricated. These cells demonstrate an energy density surpassing 250 Wh kg⁻¹ and an initial discharge capacity of 3.7 Ah under challenging conditions (S-loading > 5 mg cm⁻² and E/S < 3.5 µL mg⁻¹).