Hierarchical Porous Carbon by Ultrasonic Spray Pyrolysis Yields Stable Cycling in Lithium–Sulfur Battery

• Published in: Nano letters Vol. 14; no. 8; pp. 4418 - 4425
• Main Authors: Jung, Dae Soo, Hwang, Tae Hoon, Lee, Ji Hoon, Koo, Hye Young, Shakoor, Rana A, Kahraman, Ramazan, Jo, Yong Nam, Park, Min-Sik, Choi, Jang Wook
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 13-08-2014
• Subjects: Applied sciences; Chemical synthesis methods; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Exact sciences and technology; Materials science; Methods of nanofabrication; Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals; Physics; Structure of solids and liquids; crystallography; lithium−sulfur battery; Bimodal porous carbon; small sulfur; spray pyrolysis; hierarchical porous carbon; Lithium battery; Pyrolysis; High density; High energy; Long chain; Porous materials; Energy density; Carbon; Dissolution; Lithium sulfur batteries; Crystal structure
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl501383g

Utilizing the unparalleled theoretical capacity of sulfur reaching 1675 mAh/g, lithium–sulfur (Li–S) batteries have been counted as promising enablers of future lithium ion battery (LIB) applications requiring high energy densities. Nevertheless, most sulfur electrodes suffer from insufficient cycle lives originating from dissolution of lithium polysulfides. As a fundamental solution to this chronic shortcoming, herein, we introduce a hierarchical porous carbon structure in which meso- and macropores are surrounded by outer micropores. Sulfur was infiltrated mainly into the inner meso- and macropores, while the outer micropores remained empty, thus serving as a “barricade” against outward dissolution of long-chain lithium polysulfides. On the basis of this systematic design, the sulfur electrode delivered 1412 mAh/gsulfur with excellent capacity retention of 77% after 500 cycles. Also, a control study suggests that even when sulfur is loaded into the outer micropores, the robust cycling performance is preserved by engaging small sulfur crystal structures (S2–4). Furthermore, the hierarchical porous carbon was produced in ultrahigh speed by scalable spray pyrolysis. Each porous carbon particle was synthesized through 5 s of carrier gas flow in a reaction tube.