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Adam G. Simmonds

Bio: Adam G. Simmonds is an academic researcher from University of Arizona. The author has contributed to research in topics: Vulcanization & Sulfur. The author has an hindex of 15, co-authored 23 publications receiving 1940 citations.
Topics: Vulcanization, Sulfur, Colloidal gold, OLED, PEDOT:PSS

Papers
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Journal ArticleDOI
TL;DR: A facile method to prepare chemically stable and processable polymeric materials through the direct copolymerization of elemental sulfur with vinylic monomers is reported, which leads to well-defined sulfur-rich micropatterned films created by imprint lithography.
Abstract: An excess of elemental sulfur is generated annually from hydrodesulfurization in petroleum refining processes; however, it has a limited number of uses, of which one example is the production of sulfuric acid. Despite this excess, the development of synthetic and processing methods to convert elemental sulfur into useful chemical substances has not been investigated widely. Here we report a facile method (termed ‘inverse vulcanization’) to prepare chemically stable and processable polymeric materials through the direct copolymerization of elemental sulfur with vinylic monomers. This methodology enabled the modification of sulfur into processable copolymer forms with tunable thermomechanical properties, which leads to well-defined sulfur-rich micropatterned films created by imprint lithography. We also demonstrate that these copolymers exhibit comparable electrochemical properties to elemental sulfur and could serve as the active material in Li–S batteries, exhibiting high specific capacity (823 mA h g−1 at 100 cycles) and enhanced capacity retention. A polymerization method for converting elemental sulfur into a chemically stable, processable and electrochemically active copolymer has been described. This methodology — termed inverse vulcanization — is conducted by a one-step process using liquid sulfur, as both reaction medium and reactant, and vinylic comonomers to form polymeric materials with a high content of sulfur (50–90 wt%).

938 citations

Journal ArticleDOI
TL;DR: High quality imaging in the near (1.5 μm) and mid-IR regions using high refractive index polymeric lenses from these sulfur materials was demonstrated.
Abstract: Polymers for IR imaging: The preparation of high refractive index polymers (n = 1.75 to 1.86) via the inverse vulcanization of elemental sulfur is reported. High quality imaging in the near (1.5 μm) and mid-IR (3-5 μm) regions using high refractive index polymeric lenses from these sulfur materials was demonstrated.

273 citations

Journal ArticleDOI
TL;DR: Sulfur-rich copolymers based on poly(sulfur random-1,3-diisopropenylbenzene) (poly(S-r-DIB)) were synthesized via inverse vulcanization to create cathode materials for Li-S batteries.
Abstract: Sulfur-rich copolymers based on poly(sulfur-random-1,3-diisopropenylbenzene) (poly(S-r-DIB)) were synthesized via inverse vulcanization to create cathode materials for lithium–sulfur battery applications. These materials exhibit enhanced capacity retention (1005 mAh/g at 100 cycles) and battery lifetimes over 500 cycles at a C/10 rate. These poly(S-r-DIB) copolymers represent a new class of polymeric electrode materials that exhibit one of the highest charge capacities reported, particularly after extended charge–discharge cycling in Li–S batteries.

257 citations

Journal ArticleDOI
TL;DR: In this paper, the surface characterization of commercially available indium-tinoxide (ITO) thin films, using photoelectron spectroscopies (XPS and UPS) and electrochemistry of chemisorbed probe molecules such as ferrocene dicarboxylic acid (Fc(COOH)2), 3-thiophene acetic acid (3-TAA), and subsequent modification of these interfaces with electrochemically grown conducting polymer (CP) films is introduced.

205 citations

Journal ArticleDOI
TL;DR: In this paper, high sulfur content copolymers were prepared via inverse vulcanization of sulfur with 1,4-diphenylbutadiyne (DiPhDY) for use as the active cathode material in lithium-sulfur batteries.
Abstract: High sulfur content copolymers were prepared via inverse vulcanization of sulfur with 1,4-diphenylbutadiyne (DiPhDY) for use as the active cathode material in lithium–sulfur batteries. These sulfur-rich polymers exhibited excellent capacity retention (800 mA h g−1 at 300 cycles) and extended battery lifetimes of over 850 cycles at C/5 rate.

132 citations


Cited by
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Journal ArticleDOI
TL;DR: A review of post-lithium-ion batteries is presented in this paper with a focus on their operating principles, advantages and the challenges that they face, and the volumetric energy density of each battery is examined using a commercial pouch-cell configuration.
Abstract: Energy density is the main property of rechargeable batteries that has driven the entire technology forward in past decades. Lithium-ion batteries (LIBs) now surpass other, previously competitive battery types (for example, lead–acid and nickel metal hydride) but still require extensive further improvement to, in particular, extend the operation hours of mobile IT devices and the driving mileages of all-electric vehicles. In this Review, we present a critical overview of a wide range of post-LIB materials and systems that could have a pivotal role in meeting such demands. We divide battery systems into two categories: near-term and long-term technologies. To provide a realistic and balanced perspective, we describe the operating principles and remaining issues of each post-LIB technology, and also evaluate these materials under commercial cell configurations. Post-lithium-ion batteries are reviewed with a focus on their operating principles, advantages and the challenges that they face. The volumetric energy density of each battery is examined using a commercial pouch-cell configuration to evaluate its practical significance and identify appropriate research directions.

3,314 citations

Journal ArticleDOI
TL;DR: This review aims to summarize major developments in the field of lithium-sulfur batteries, starting from an overview of their electrochemistry, technical challenges and potential solutions, along with some theoretical calculation results to advance the understanding of the material interactions involved.
Abstract: Due to their high energy density and low material cost, lithium–sulfur batteries represent a promising energy storage system for a multitude of emerging applications, ranging from stationary grid storage to mobile electric vehicles. This review aims to summarize major developments in the field of lithium–sulfur batteries, starting from an overview of their electrochemistry, technical challenges and potential solutions, along with some theoretical calculation results to advance our understanding of the material interactions involved. Next, we examine the most extensively-used design strategy: encapsulation of sulfur cathodes in carbon host materials. Other emerging host materials, such as polymeric and inorganic materials, are discussed as well. This is followed by a survey of novel battery configurations, including the use of lithium sulfide cathodes and lithium polysulfide catholytes, as well as recent burgeoning efforts in the modification of separators and protection of lithium metal anodes. Finally, we conclude with an outlook section to offer some insight on the future directions and prospects of lithium–sulfur batteries.

1,816 citations

Journal ArticleDOI
TL;DR: In this paper, the authors highlight the recent progress in high-sulfur-loading Li-S batteries enabled by hierarchical design principles at multiscale, particularly, basic insights into the interfacial reactions, strategies for mesoscale assembly, unique architectures, and configurational innovation in the cathode, anode, and separator.
Abstract: Owing to high specific energy, low cost, and environmental friendliness, lithium–sulfur (Li–S) batteries hold great promise to meet the increasing demand for advanced energy storage beyond portable electronics, and to mitigate environmental problems. However, the application of Li–S batteries is challenged by several obstacles, including their short life and low sulfur utilization, which become more serious when sulfur loading is increased to the practically accepted level above 3–5 mg cm−2. More and more efforts have been made recently to overcome the barriers toward commercially viable Li–S batteries with a high sulfur loading. This review highlights the recent progress in high-sulfur-loading Li–S batteries enabled by hierarchical design principles at multiscale. Particularly, basic insights into the interfacial reactions, strategies for mesoscale assembly, unique architectures, and configurational innovation in the cathode, anode, and separator are under specific concerns. Hierarchy in the multiscale design is proposed to guide the future development of high-sulfur-loading Li–S batteries.

1,364 citations

Journal ArticleDOI
TL;DR: A facile method to prepare chemically stable and processable polymeric materials through the direct copolymerization of elemental sulfur with vinylic monomers is reported, which leads to well-defined sulfur-rich micropatterned films created by imprint lithography.
Abstract: An excess of elemental sulfur is generated annually from hydrodesulfurization in petroleum refining processes; however, it has a limited number of uses, of which one example is the production of sulfuric acid. Despite this excess, the development of synthetic and processing methods to convert elemental sulfur into useful chemical substances has not been investigated widely. Here we report a facile method (termed ‘inverse vulcanization’) to prepare chemically stable and processable polymeric materials through the direct copolymerization of elemental sulfur with vinylic monomers. This methodology enabled the modification of sulfur into processable copolymer forms with tunable thermomechanical properties, which leads to well-defined sulfur-rich micropatterned films created by imprint lithography. We also demonstrate that these copolymers exhibit comparable electrochemical properties to elemental sulfur and could serve as the active material in Li–S batteries, exhibiting high specific capacity (823 mA h g−1 at 100 cycles) and enhanced capacity retention. A polymerization method for converting elemental sulfur into a chemically stable, processable and electrochemically active copolymer has been described. This methodology — termed inverse vulcanization — is conducted by a one-step process using liquid sulfur, as both reaction medium and reactant, and vinylic comonomers to form polymeric materials with a high content of sulfur (50–90 wt%).

938 citations

Journal ArticleDOI
TL;DR: It is demonstrated that the Li2S decomposition energy barrier is associated with the binding between isolated Li ions and the sulfur in sulfides; this is the main reason that sulfide materials can induce lower overpotential compared with commonly used carbon materials.
Abstract: Polysulfide binding and trapping to prevent dissolution into the electrolyte by a variety of materials has been well studied in Li−S batteries. Here we discover that some of those materials can play an important role as an activation catalyst to facilitate oxidation of the discharge product, Li2S, back to the charge product, sulfur. Combining theoretical calculations and experimental design, we select a series of metal sulfides as a model system to identify the key parameters in determining the energy barrier for Li2S oxidation and polysulfide adsorption. We demonstrate that the Li2S decomposition energy barrier is associated with the binding between isolated Li ions and the sulfur in sulfides; this is the main reason that sulfide materials can induce lower overpotential compared with commonly used carbon materials. Fundamental understanding of this reaction process is a crucial step toward rational design and screening of materials to achieve high reversible capacity and long cycle life in Li−S batteries.

933 citations