Sulfur\nVapor-Infiltrated 3D Carbon Nanotube Foam for\nBinder-Free High Areal Capacity Lithium–Sulfur Battery Composite\nCathodes

Abstract

Here,\nwe demonstrate a strategy to produce high areal loading and\nareal capacity sulfur cathodes by using vapor-phase infiltration of\nlow-density carbon nanotube (CNT) foams preformed by solution processing\nand freeze-drying. Vapor-phase capillary infiltration of sulfur into\npreformed and binder-free low-density CNT foams leads to a mass loading\nof ∼79 wt % arising from interior filling and coating of CNTs\nwith sulfur while preserving conductive CNT–CNT junctions that\nsustain electrical accessibility through the thick foam. Sulfur cathodes\nare then produced by mechanically compressing these foams into dense\ncomposites (ρ > 0.2 g/cm³), revealing specific\ncapacity\nof 1039 mAh/g_S at 0.1 C, high sulfur areal loading of 19.1\nmg/cm², and high areal capacity of 19.3 mAh/cm². This work highlights a technique broadly adaptable to a diverse\ngroup of nanostructured building blocks where preformed low-density\nmaterials can be vapor infiltrated with sulfur, mechanically compressed,\nand exhibit simultaneous high areal and gravimetric storage properties.\nThis provides a route for scalable, low-cost, and high-energy density\nsulfur cathodes based on conventional solid electrode processing routes.