A\nCarbon-Cotton Cathode with Ultrahigh-Loading Capability\nfor Statically and Dynamically\nStable Lithium–Sulfur Batteries

Abstract

Sulfur\nexhibits a high theoretical capacity of 1675 mA h g^–1 <i>via</i> a distinct conversion reaction,\nwhich is different from the insertion reactions in commercial lithium-ion\nbatteries. In consideration of its conversion-reaction battery chemistry,\na custom design for electrode materials could establish the way for\nattaining high-loading capability while simultaneously maintaining\nhigh electrochemical utilization and stability. In this study, this\nprocess is undertaken by introducing carbon cotton as an attractive\nelectrode-containment material for enhancing the dynamic and static\nstabilities of lithium–sulfur (Li–S) batteries. The\ncarbon cotton possessing a hierarchical macro-/microporous architecture\nexhibits a high surface area of 805 m² g^–1 and high microporosity with a micropore area of 557 m² g^–1. The macroporous channels allow the carbon\ncotton to load and stabilize a high amount of active material. The\nabundant microporous reaction sites spread throughout the carbon cotton\nfacilitate the redox chemistry of the high-loading/content Li–S\nsystem. As a result, the high-loading carbon-cotton cathode exhibits\n(i) enhanced cycle stability with a good dynamic capacity retention\nof 70% after 100 cycles and (ii) improved cell-storage stability with\na high static capacity retention of above 93% and a low time-dependent\nself-discharge rate of 0.12% per day after storing for a long period\nof 60 days. These carbon-cotton cathodes with the remarkably highest\nvalues reported so far of both sulfur loading (61.4 mg cm^–2) and sulfur content (80 wt %) demonstrate enhanced electrochemical\nutilization with the highest areal, volumetric, and gravimetric capacities\nsimultaneously.