Developing High Energy Density Li-S Batteries via Pore-Structure Regulation of Porous Carbon Based Electrocatalyst

The mesopores and macropores within porous carbon materials help increase the surface for the depostion of solid-state products, reduce the Li₂S film thickness, enhance electron and mass transport, and accelerate the reaction kinetics. However, an excessive amount of mesopores and macropores can lead to increased electrolyte consumption, particularly at high sulfur loadings, where excessive electrolyte usage hampers the enhancement of practical energy density in lithium-sulfur (Li-S) batteries. A rational pore structure can minimize the amount of electrolyte to fill the pores, thereby reducing electrolyte consumption while achieving rapid reaction kinetics and a high gravimetric energy density. In this work, the pore structure of carbon nanosheet-based electrocatalysts is precisely controlled by adjusting the content of a water-soluble potassium chloride template, allowing for in-depth investigation of the relationship between pore structure, electrolyte usage, and electrochemical performance in Li-S batteries. The molybdenum carbide-embedded carbon nanosheet (MoC-CNS) electrocatalyst, with an optimized pore structure, facilitates exceptional electrochemical performance under high sulfur loading and lean electrolyte conditions. Ultimately, the MoC-CNS-3-based Li-S battery achieved stable operation over 50 cycles under high sulfur loading (12 mg cm^-2) and a low electrolyte-to-sulfur (E/S) ratio of 4 uL mg^-1, delivering a high gravimetric energy density of 354.5 Wh kg^-1. This work provides a viable strategy for developing high-performance Li-S batteries.