Designing\nLithium–Sulfur Batteries with High-Loading\nCathodes at a Lean Electrolyte Condition

Abstract

Developing\nlithium–sulfur cells with a high-loading cathode\nat a lean-electrolyte condition is the key to bringing the lithium–sulfur\ntechnology into the energy-storage market. However, it has proven\nto be extremely challenging to develop a cell that simultaneously\nsatisfies the abovementioned metrics while also displaying high electrochemical\nefficiency and stability. Here, we present a concept of constructing\na conductive cathode substrate with a low surface area and optimized\nnanoporosity (i.e., limited micropores in the porous matrix) that\nenables achieving a high sulfur loading of 13 mg cm^–2 and a high sulfur content of 75 wt % with an extremely low electrolyte/sulfur\nratio of just 4.0 μL mg^–1. The high-loading\nnanocomposite cathodes demonstrate high-areal capacities of 9.3 mA\nh cm^–2, high energy densities of 18.6 mW h cm^–2, and superior cyclability with excellent capacity\nretention of 85% after 200 cycles. These values are higher than the\nbenchmarks set up for developing future commercial lithium–sulfur\ncells (i.e., areal capacity of >2–4 mA h cm^–2, energy density of >8–13 mW h cm^–2,\nand\na long cycle life of 200 cycles with a capacity retention of 80%).\nThe cathode design further exhibits high-rate capability from C/20\nto 1 C rates and great potential to attain ultrahigh sulfur loading\nand a content of 17 mg cm^–2 and 80 wt %. The key\nnanostructural feature that enables realizing fast-charge transport\nis the low surface area and limited microporosity that avoid the fast\nconsumption of the electrolyte during cell cycling.