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A Scalable Synthesis of Honeycomb-like Ordered Mesoporous Carbon Nanosheets and their Application in Lithium-Sulfur Batteries Seung-Keun Park, Jeongyeon Lee, Taejin Hwang, Byungchul Jang, and Yuanzhe Piao ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.6b13370 • Publication Date (Web): 23 Dec 2016 Downloaded from http://pubs.acs.org on December 25, 2016
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ACS Applied Materials & Interfaces
A Scalable Synthesis of Honeycomb-like Ordered Mesoporous Carbon Nanosheets and their Application in Lithium-Sulfur Batteries
Seung-Keun Park,‡a Jeongyeon Lee,‡a Taejin Hwang,a Byungchul Jang,a Yuanzhe Piao*a,b,d
a
Program in Nano Science and Technology, Graduate School of Convergence Science and Technology, Seoul National University, 145 Gwanggyo-ro, Yeongtong-gu, Suwon–si, Gyeonggi-do, 443-270, Republic of Korea. b
Advanced Institutes of Convergence Technology, 145 Gwanggyo-ro, Yeongtong-gu, Suwon–si, Gyeonggi-do, 443-270, Republic of Korea.
*Corresponding author: Yuanzhe Piao:
[email protected]; ‡
These authors contributed equally to this work
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ACS Applied Materials & Interfaces
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Keywords: Honeycomb-like structure, ordered mesoporous carbon, 2D carbon nanosheets, lithium-sulfur battery, cathode host
Abstract There is a growing need to improve the electrical conductivity of the cathode and to suppress the rapid capacity decay during cycling in lithium-sulfur (Li–S) batteries. This can be achieved by developing facile methods for the synthesis of novel nanostructured carbon materials that can function as effective cathode hosts. In this paper, we report the scalable synthesis of ordered mesoporous carbon nanosheets (OMCNS) via the etching of selfassembled iron oxide/carbon hybrid nanosheets (IO–C NS), which serve as an advanced sulfur host for Li–S batteries. The obtained two-dimensional (2D) nanosheets have closepacked uniform cubic mesopores of ~20 nm side length, and the gap between the pores is ~4 nm, which resembles the honeycomb structure consisting of an ordered array of hexagonal pores. We loaded OMCNS with sulfur by a simple melting infusion process, and evaluated the performance of the resulting OMCNS-sulfur composites as the cathode material. As a result, the OMCNS–S electrode infiltrated with 70 wt% sulfur delivers a high and stable reversible capacity of 505.7 mA h g-1 after 500 cycles at 0.5 C-rate with excellent capacity retention (a decay of 0.081% per cycle) and excellent rate capability (580.6 mA h g-1 at a high current density of 2 C). The improved electrochemical properties could be attributed to the fact that the uniform cubic mesopores offer sufficient space for the volume expansion of sulfur inside them, and trap the polysulfides during the charging-discharging process. Therefore, these unique structured carbon nanosheets can be promising candidates for other energy storage applications.
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ACS Applied Materials & Interfaces
1. Introduction With the increasing need for inexpensive and efficient energy storage devices, rechargeable lithium-sulfur (Li–S) batteries have become one of the more promising candidates for next-generation battery systems because of their high theoretical energy density (2600 W h kg-1), high theoretical specific capacity (1675 mA h g-1), environmental friendliness, and economic cost.1-3 In spite of these considerable advantages, the use of sulfur as cathode causes serious problems that hinder their commercialization. Firstly, sulfur and its intermediate products Li2Sx formed during cycling (x = 1–8) show poor electronic and ionic conductivities, which result in poor active-material utilization.4-5 Secondly, the intermediate products Li2Sx (mainly 2
