Material, configuration, and fabrication designs for lean-electrolyte lithium–sulfur cell with a high-loading sulfur cathode

Abstract

The lithium–sulfur battery is considered a promising candidate for third-generation commercial rechargeable batteries because of the high theoretical capacity of sulfur (1675 mA h g−1). However, the insulating solid-state active material causes low sulfur loading and content, challenging the increase of the energy density. The complex conversion reaction between solid-state and liquid-state active materials during charging/discharging process leads to high electrolyte usage and short cycle life. These issues affecting the evaluation of the electrochemical characteristics and performance of lithium–sulfur batteries are important for the commercialization of this technology. Herein, we propose a design of cathode material, configuration, and fabrication. This design realizes a porous carbon electrospun substrate built up with nonwoven carbon nanofibers having low nanoporosity. The carbon electrospun substrate is used as a porous electrode substrate to encapsulate insulating sulfur using a hot-pressing method, forming a hot-pressed electrospun cathode. The carbon electrospun substrate has a conductive, low-weight network to accommodate and exploit a high amount of sulfur (8 mg cm−2 and 73 wt%) at low electrolyte-to-sulfur ratios (7–4 μL mg−1), which achieves high charge-storage capacity (740 mA h g−1), large energy density (11.8 mW h cm−2), excellent rate performance (C/20–C/2 rates), and a prolonged cycle life (200 cycles).