Toward Practical High-Energy Batteries: A Modular-Assembled Oval-Like Carbon Microstructure for Thick Sulfur Electrodes

The modular assembly of microstructures from simple nanoparticles offers a powerful strategy for creating materials with new functionalities. Such microstructures have unique physicochemical properties originating from confinement effects. Here, the modular assembly of scattered ketjen black nanoparticles into an oval-like microstructure via double "Fischer esterification," which is a form of surface engineering used to fine-tune the materials surface characteristics, is presented. After carbonization, the oval-like carbon microstructure shows promise as a candidate sulfur host for the fabrication of thick sulfur electrodes. Indeed, a specific discharge capacity of 8.417 mAh cm^-2 at 0.1 C with a high sulfur loading of 8.9 mg cm^-2 is obtained. The large-scale production of advanced lithium-sulfur battery pouch cells with an energy density of 460.08 Wh kg^-1 @18.6 Ah is also reported. This work provides a radically different approach for tuning the performance of a variety of surfaces for energy storage materials and biological applications by reconfiguring nanoparticles into desired structures.