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

Abstract

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.