The Li-S battery has been under intense scrutiny for over two decades, as it offers the possibility of high gravimetric capacities and theoretical energy densities ranging up to a factor of five beyond conventional Li-ion systems. Herein, we report the feasibility to approach such capacities by creating highly ordered interwoven composites. The conductive mesoporous carbon framework precisely constrains sulphur nanofiller growth within its channels and generates essential electrical contact to the insulating sulphur. The structure provides access to Li+ ingress/egress for reactivity with the sulphur, and we speculate that the kinetic inhibition to diffusion within the framework and the sorption properties of the carbon aid in trapping the polysulphides formed during redox. Polymer modification of the carbon surface further provides a chemical gradient that retards diffusion of these large anions out of the electrode, thus facilitating more complete reaction. Reversible capacities up to 1,320 mA h g(-1) are attained. The assembly process is simple and broadly applicable, conceptually providing new opportunities for materials scientists for tailored design that can be extended to many different electrode materials.

http://dns2.asia.edu.tw/~ysho/YSHO-English/1000%20WC/PDF/Nat%20Mat8,%20500.pdf

A highly ordered nanostructured carbon–sulphur cathode for lithium–sulphur batteries

Electrolytes and interphases in Li-ion batteries and beyond.

Rechargeable Li/S batteries have attracted significant attention lately due to their high specific energy and low cost. They are promising candidates for applications, including portable electronics, electric vehicles and grid-level energy storage. However, poor cycle life and low power capability are major technical obstacles. Various nanostructured sulfur cathodes have been developed to address these issues, as they provide greater resistance to pulverization, faster reaction kinetics and better trapping of soluble polysulfides. In this review, recent developments on nanostructured sulfur cathodes and mechanisms behind their operation are presented and discussed. Moreover, progress on novel characterization of sulfur cathodes is also summarized, as it has deepened the understanding of sulfur cathodes and will guide further rational design of sulfur electrodes.

Nanostructured sulfur cathodes

Lithium-sulfur (Li-S) batteries have attracted tremendous interest because of their high theoretical energy density and cost effectiveness. The target of Li-S battery research is to produce batteries with a high useful energy density that at least outperforms state-of-the-art lithium-ion batteries. However, due to an intrinsic gap between fundamental research and practical applications, the outstanding electrochemical results obtained in most Li-S battery studies indeed correspond to low useful energy densities and are not really suitable for practical requirements. The Li-S battery is a complex device and its useful energy density is determined by a number of design parameters, most of which are often ignored, leading to the failure to meet commercial requirements. The purpose of this review is to discuss how to pave the way for reliable Li-S batteries. First, the current research status of Li-S batteries is briefly reviewed based on statistical information obtained from literature. This includes an analysis of how the various parameters influence the useful energy density and a summary of existing problems in the current Li-S battery research. Possible solutions and some concerns regarding the construction of reliable Li-S batteries are comprehensively discussed. Finally, insights are offered on the future directions and prospects in Li-S battery field.

More Reliable Lithium-Sulfur Batteries: Status, Solutions and Prospects.

The commercialization of lithiumsulfur bat- teriesishindered bylowcycle stabilityandlowefficiency,which are induced by sulfur active material loss and polysulfide shuttle reaction through dissolution into electrolyte. In this study, sulfur-impregnated disordered carbon nanotubes are synthe- sized as cathode material for the lithiumsulfur battery. The obtained sulfurcarbon tube cathodes demonstrate superior cyclability and Coulombic efficiency. More importantly, the electrochemical characterization indicates a new stabilization mechanism of sulfur in carbon induced by heat treatment.

Sulfur-impregnated disordered carbon nanotubes cathode for lithium-sulfur batteries.

Discharge behavior of lithium/sulfur cell with TEGDME based electrolyte at low temperature

Root-like porous carbon nanofibers with high sulfur loading enabling superior areal capacity of lithium sulfur batteries

A ternary sulfur/polyaniline/carbon composite as cathode material for lithium sulfur batteries

Lithium sulfur (Li–S) batteries have been considered as a promising candidate for high energy density applications with a high theoretical capacity of 1675 mAh g–1 and a high energy density of 2600 Wh kg–1. In this work, a polyaniline (PANi)-coated mesoporous carbon composite is synthesized by direct polymerization of aniline monomer in mesoporous Ketjenblack (KB) carbon and is used as cathode material for Li–S batteries. Different mass percentages of PANi can be infiltrated into the pores of KB carbon by simply varying the amount of monomer. Sulfur is encapsulated into the composite by the melt diffusion method, and the electrochemical performance of lithium sulfur batteries is investigated. The results indicate that the mass percentage of PANi plays a crucial role in the cycle stability of lithium sulfur batteries. The infiltrated PANi is capable of enhancing the intimate contact of sulfur with carbon and trapping polysulfides, which improves the utilization of active material. However, excess PANi dimi...

Polyaniline-Coated Mesoporous Carbon/Sulfur Composites for Advanced Lithium Sulfur Batteries

A highly ordered mesoporous sulfurized polyacrylonitrile (MSPAN) composite has been synthesized via in situ polymerization of polyacrylonitrile (PAN) in an SBA-15 template followed by sulfurization. The synthesized composite possessed high sulfur utilization, high Coulombic efficiency, and excellent cycling stability as a cathode active material for high-rate lithium sulfur (Li–S) batteries. A highly ordered mesoporous structure was observed in the MSPAN composite from transmission electron microscopy. Excellent electrochemical and stable cycling performances of the MSPAN composite were obtained, especially at high C rates. The capacity retention of the MSPAN cell was 755 mAh g–1 after 200 cycles at 1 C and 610 mAh g–1 after 900 cycles at 2 C. Even at a higher rate of 5 C, the composite showed reasonable capacity retention. The superior performance of the MSPAN composite was attributed to its highly porous structure, which could effectively improve the wettability, accessibility, and absorption of electro...

Kwon-Koo Cho

Papers

Discharge behavior of lithium/sulfur cell with TEGDME based electrolyte at low temperature

Root-like porous carbon nanofibers with high sulfur loading enabling superior areal capacity of lithium sulfur batteries

A ternary sulfur/polyaniline/carbon composite as cathode material for lithium sulfur batteries

Polyaniline-Coated Mesoporous Carbon/Sulfur Composites for Advanced Lithium Sulfur Batteries

Highly Ordered Mesoporous Sulfurized Polyacrylonitrile Cathode Material for High-Rate Lithium Sulfur Batteries