Gel based sulfur cathodes with a high sulfur content and large mass loading for high-performance lithium-sulfur batteries

A significantly improved conductive matrix design for the sulfur electrode is essential to solve several problems related to sulfur electrochemistry toward the development of practical lithium-sulfur batteries (LSBs). Great progress has been made by using a variety of carbon-based nanostructures for physically and chemically confining soluble polysulfides as well as providing conductive paths. However, most of these electrode designs have a low sulfur content or a low sulfur loading, leading to a low specific capacity or low areal capacity at the electrode level. Herein, intrinsically N- and O-doped carbon nanoribbon (CNR) aerogels, obtained by pyrolysis of bacterial cellulose (BC) aerogels, were employed to form gel-based sulfur cathodes, simultaneously achieving both a high sulfur content and a high sulfur loading. With a sulfur loading of 6.4 mg cm^-2 and a sulfur content of 90% at the whole electrode (including the current collector) level, a capacity as high as 943 mA h g^-1 was achieved, which corresponds to an areal capacity of 5.9 mA h cm^-2. The outstanding cell performance is attributed to the gel based cathode structure, which can strongly hold a large amount of the catholyte and relieve the shuttle effect of lithium polysulfides.