A Freestanding, Dissolution- and Diffusion-Limiting, Flexible Sulfur Electrode Enables High Specific Capacity at High Mass Loading.

Abstract

The acquisition of stable and high-areal-capacity S cathodes over 10 mA h cm^-2 is a critical and indispensable step to realize the high energy density configuration. However, increasing the areal capacity of S cathodes often deteriorates the specific capacity and stability due to the aggravated dissolution of S and diffusion of solvable polysulfides in the thick electrode. Herein, the design of a freestanding composite cathode that leverages 3D covalent binding sites and chemical adsorption environment to offer dissolution-limiting and diffusion-blocking functions of S species is reported. By employing this architecture, the coin cell exhibits excellent cycling stability and an exceptional specific capacity of 1444.3 mA h g^-1 (13 mA h cm^-2), and the pouch cell configuration manifests a noteworthy areal capacity exceeding 11 mA h cm^-2. This performance is coupled with excellent flexibility, demonstrated through consecutive bending cycle tests, even at a sulfur loading of 9.00 mg cm^-2. This study lays the foundation for the development of flexible Li-S batteries with increased loading capacities and exceptional performance.