In the pursuit of high-energy-density batteries, there is tremendous appetite for developing the lithium-sulfur technology with high sulfur loading and content while keeping the electrolyte/sulfur (E/S) ratio low to be competitive with or surpass the current lithium-ion technology. However, very limited studies have focused on keeping these parameters at practically desirable ranges. Here, we present a lithium-sulfur cell with a coaxial-graphene-coated cotton-carbon (CGCC) cathode that displays excellent performance with high sulfur loading (57.6 mg cm−2), high sulfur content (75 wt %), and low E/S ratio (4.2 μL mg−1) simultaneously. The cell exhibits high areal capacity (31 mA hr cm−2) and areal energy density (66 mW hr cm−2) that exceed the areal capacity (4 mA hr cm−2) and areal energy density (10 mW hr cm−2) of a commercial LiCoO2 cathode with a high capacity-retention rate of 68% over 200 cycles. The capacity limitation of insertion-compound cathodes hampers the development of high-energy-density lithium-ion batteries and thus has generated immense interest in conversion-reaction cathodes, such as sulfur. With no restriction to maintain their initial physicochemical properties, sulfur cathodes offer a high theoretical capacity (1,675 mA hr g−1). However, the amounts of sulfur and electrolyte that drastically affect the battery electrochemistry have been ignored for years; thereby, the cathode performances have often been overrated. With regard to these challenges, we present a coaxial-graphene-coated cotton-carbon material as an excellent cathode substrate that simultaneously satisfies the demand for high sulfur loading, high sulfur content, low electrolyte/sulfur ratio, and superior electrochemical efficiency and stability. Benefiting from the high-loading cathode configuration, the cell attains high areal capacity and energy density with long-term cycle stability. Professor Manthiram and Dr. Chung present a coaxial-graphene-coated cotton-carbon material as an excellent cathode substrate that simultaneously satisfies the demand for high sulfur loading, high sulfur content, low electrolyte amount, and superior electrochemical efficiency and stability. Benefiting from a high-loading cathode configuration, the cells attain areal capacity and energy density of 8 and 7 times higher, respectively, than those obtained with a commercial LiCoO2 cathode. The coaxial-graphene-coated cotton-carbon cathode demonstrates a promising direction for the establishment of practical lithium-sulfur battery technology.
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