Subscriber access provided by Service des bibliothèques | Université de Sherbrooke
Energy, Environmental, and Catalysis Applications
3D Carbon Current Collector Promises Small Sulfur Molecules Cathode with High Areal Loading for Lithium-Sulfur Batteries Qian Zhao, Qizhen Zhu, Jiawei Miao, Zhaoruxin Guan, Huan Liu, Renjie Chen, Yabin An, Feng Wu, and Bin Xu ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b00225 • Publication Date (Web): 13 Mar 2018 Downloaded from http://pubs.acs.org on March 14, 2018
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 29 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
3D Carbon Current Collector Promises Small Sulfur Molecules Cathode with High Areal Loading for Lithium-Sulfur Batteries Qian Zhaoa, Qizhen Zhu a, Jiawei Miao a, Zhaoruxin Guan a, Huan Liu a,b, Renjie Chen b, Yabin An a, Feng Wu b, Bin Xu a,*
a
State Key Laboratory of Organic-Inorganic Composites, Beijing Key Laboratory of
Electrochemical Process and Technology for Materials, Beijing University of Chemical Technology, Beijing, China 100029 b
School of Materials Science & Engineering, Beijing Key Laboratory of Environmental Science
and Engineering, Beijing Institute of Technology, Beijing 100081, China KEYWORDS: Ultra-microporous carbon, Small sulfur molecules, Carbon foam, Lithium sulfur batteries, 3D current collector, High areal sulfur loading
ACS Paragon Plus Environment
1
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 2 of 29
ABSTRACT With the high energy density of 2600 Wh kg-1, lithium-sulfur (Li-S) batteries have been considered as one of the most promising energy storage systems. However, the serious capacity fading resulting from shuttle effect hinders its commercial application. Encapsulating small S2–4 molecules into the pores of ultra-microporous carbon (UMC) can eliminate the dissolved polysulfudes, thus completely inhibit the shuttle effect. Nevertheless, the sulfur loading of S24/UMC
is usually not higher than 1 mg cm-2 due to the limited pore volume of UMC, which is a
great challenge for small sulfur cathode. In this paper, by applying ultra-light 3D melamine formaldehyde-based carbon foam (MFC) as current collector, we dramatically enhanced the areal sulfur loading of the S2-4 electrode with good electrochemical performance. The 3D skeleton of MFC can hold massive S2-4/UMC composites and act as a conductive network for fast transfer of electrons and Li+ ions. Furthermore, it can serve as an electrolyte reservoir to make a sufficient contact between S2-4 and electrolyte, enhancing the utilization of S2-4. With the MFC current collector, the S2-4 electrode reaches an areal sulfur loading of 4.2 mg cm-2 and performs a capacity of 839.8 mAh g-1 as well as a capacity retention of 82.5% after 100 cycles. The 3D MFC current collector provides a new insight for the application of Li-S batteries with high areal small sulfur loading and excellent cycle stability.
1. INTRODUCTION As one of the most promising energy storage systems, lithium sulfur (Li-S) batteries perform high energy density of 2600 Wh kg-1. Furthermore, sulfur with high theoretical specific capacity of 1675 mAh g-1 is low cost, environmentally friendly, and abundant on the earth, which
ACS Paragon Plus Environment
2
Page 3 of 29 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
improves the competitiveness of Li-S batteries in next-generation long-distance electric vehicles.1-3 However, the commercialization of Li-S batteries faces some intrinsic problems. The insulativity of sulfur and the generated Li2S /Li2S2 decreases the utilization of the active materials and results in inferior capacity; the shuttle effect of the polysulfides leads to serious capacity fading and poor cycle stability; the volumetric expansion of sulfur and Li2S causes the structure damage of the electrode. 4-5 Many researches have been devoted to addressing these problems and improving the performance of sulfur electrode,6,
7
including (1) physically confining the sulfur in porous
conductive materials,8-10 (2) chemical binding the sulfur / polysulifides with heteroatom-doped carbon,11-13 transition metal oxides,14-16 MXene,17,18 TiN,19 etc., (3) structural design with graphene20-23 or carbon nanotubes24-26 to prepare free-standing electrodes or 3D electrodes,27-28 and (4) inserting a conductive interlayer between cathode and separator to inhibit the shuttle effect.29-34 All these approaches focused on inhibiting or reutilizing the polysulfides, thus restricting the migration of the polysulfides. However, the shuttle problem was alleviated, but not gotten basic settlement. In order to eliminate the shuttle effect fundamentally, one powerful method was proposed in recent years by using small S2-4 molecules instead of cyclo-S8 as the active materials for Li-S batteries. 35-37 As the redox process transferred to the solid-solid reaction between S2-4 and Li2S, dissolved polysulfides, intermediating produced from S5-8 molecules, were avoided and the shuttle effect was inhibited thoroughly. As a result, the serious capacity fading due to the migration of polysulfides was eradicated and excellent cycle stability was obtained.35 The main method to control the active sulfur in S2-4 allotropes was to physically confine the sulfur in narrow ultra-microporous carbons (UMC). This method was firstly reported by
ACS Paragon Plus Environment
3
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 4 of 29
preparing a microporous carbon with 0.7 nm pore size. After filled with sulfur via a thermal treatment process, the microporous structure of UMC can only accommodate small S2-4 and avoid the existence of cyclo-S8, which was proved by the electrochemical charge-discharge curve with only one low potential plateau at 1.8 V.36 Then another ultra-microporous carbon with 0.5 nm pore size was prepared by carbonization of D-glucose and CNTs to confine the metastable small S2-4, and the produced S2-4/carbon performed good electrochemical properties.37 Many other microporous carbons or mesoporous-microporous carbons were reported either by direct carbonization of metal-organic-frameworks (MOF),38-40 polyacrylonitrilem,41 polypyrrole spheres,42, 43 the modified sucrose,44-46 and sodium tartrate,47 or by the tunable alkali activation process.48 Recently, an ultra-microporous carbon (UMC) with 0.55 nm pore size by one-step pyrolysis of polyvinylidenefluoride (PVDF) was prepared to accommodate small S2–4 molecules by our group, which performed great cycle stability in Li-S batteries.49 The S2–4 in microporous carbon with narrow pore size (
