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

Abstract 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.