IoT-QWatch: A Novel Framework to Support the Development of Quality Aware Autonomic IoT Applications

IoT-QWatch: A Novel Framework to Support the Development of Quality Aware Autonomic IoT Application

Hollow Co_0.85Se Nanowire Array on Carbon Fiber Paper for High Rate Pseudocapacitor

A supercapacitor electrode is fabricated with Co_0.85Se hollow nanowires (HNW) array, which is synthesized by wet chemical hydrothermal selenization of initially grown cobalt hydroxyl carbonate nanowires on conductive CFP. The dense self-organized morphology of Co_0.85Se HNWs is revealed by scanning/transmission electron microscopy. The as-synthesized Co_0.85Se HNWs possess high pseudocapacitive property with high capacitance retention and high durability. The areal capacitance value is seen to vary from 929.5 to 600 mF cm^–2 (60% retention) as the current density is increased from 1 to 15 mA cm^–2, an increase of a factor of 15. Based on mass loading, this corresponds to a very high gravimetric capacitance of 674 (for 2 mA cm^–2 or 1.48 Ag^–1) and 444 Fg^1– (for 15 mA cm^–2 or 11 A g^–1) in a full-cell configuration with the Co_0.85Se HNWs as cathode and activated carbon as anode (asymmetric configuration) promising results are obtained

Nanoscale Compositional Mapping of Commercial LiNi_0.8Co_0.15Al_0.05O₂ Cathodes Using Atom Probe Tomography

Nickel-rich cathodes provide improved specific capacity, which leads to higher gravimetric energy density, which, in turn, is critical for electric vehicles. However, poor long-term capacity retention at elevated temperatures/high C rates (the rate of charge and discharge on a battery) stems from material issues: surface phase changes, corrosive side reactions with the electrolyte, ion dissolution, and propagation of cracks. Introducing dopants, developing nanoscale surface coatings, and graded core–shell structures all improved the electrochemical performance of nickel-rich cathodes. However, material-level understanding of the effect of Li composition and distribution in Ni-rich cathodes is limited due to a lack of characterization methods available that can directly image Li at the nanoscale. Hence, it is critical to establish methods such as atom probe tomography (APT) that have both nanometer-scale spatial resolution and high compositional sensitivity to quantitatively analyze battery cathodes. To fully realize its potential as a method for quantitative compositional analysis of commercial Li-ion batteries, we provide a comprehensive description of the challenges in sample preparation and analyze the dependency of the analysis parameters, specifically laser pulse energy on the measured stoichiometry of elements in a high-Ni-content cathode material LiNi0.8Co0.15Al0.05O2 (NCA). Our findings show that the stoichiometry variations cannot be explained by charge–state ratios or Ga implantation damage alone during FIB preparation, indicating that additional factors such as crystallographic orientation may need to be considered to achieve quantitative nanoscale compositional analysis of such battery cathodes using APT

Mitigating Dendrite Formation on a Zn Electrode in Aqueous Zinc Chloride by the Competitive Surface Chemistry of an Imidazole Additive

Electrochemical energy storage systems are critical in several ways for a smooth transition from nonrenewable to renewable energy sources. Zn-based batteries are one of the promising alternatives to the existing state-of-the-art Li-ion battery technology, since Li-ion batteries pose significant drawbacks in terms of safety and cost-effectiveness. Zn (with a reduction potential of −0.76 V vs SHE) has a significantly higher theoretical volumetric capacity (5851 mAh/cm3) than Li (2061 mAh/cm3), and it is certainly far less expensive, safer, and more earth-abundant. The formation of dendrites, hydrogen evolution, and the formation of a ZnO passivation layer on the Zn anode are the primary challenges in the development and deployment of rechargeable zinc batteries. In this work, we examine the role of imidazole as an electrolyte additive in 2 M ZnCl2 to prevent dendrite formation during zinc electrodeposition via experimental (kinetics and imaging) and theoretical density functional theory (DFT) studies. To characterize the efficacy and to identify the appropriate concentration of imidazole, linear sweep voltammetry (LSV) and chronoamperometry (CA) are performed with in situ monitoring of the electrodeposited zinc. The addition of 0.025 wt % imidazole to 2 M ZnCl2 increases the cycle life of Zn-symmetric cells cycled at 1 mA/cm2 for 60 min of plating and stripping dramatically from 90 to 240 h. A higher value of the nucleation overpotential is noted in the presence of imidazole, which suggests that imidazole is adsorbed at a competitively faster rate on the surface of zinc, thereby suppressing the zinc electrodeposition kinetics and the formation. X-ray tomography reveals that a short circuit caused by dendrite formation is the main plausible failure mechanism of Zn symmetric cells. It is observed that the electrodeposition of zinc is more homogeneous in the presence of imidazole, and its presence in the electrolyte also inhibits the production of a passivating coating (ZnO) on the Zn surface, thereby preventing corrosion. DFT calculations conform well with the stated experimental observations

Thin Solid Electrolyte Layers Enabled by Nanoscopic Polymer Binding

To achieve high-energy all-solid-state batteries (ASSBs), solid-state electrolytes (SE) must be thin, mechanically robust, and possess the ability to form low resistance interfaces with electrode materials. Embedding an inorganic SE into an organic polymer combines the merits of high conductivity and flexibility. However, the performance of such an SE-in-polymer matrix (SEPM) is highly dependent on the microstructure and interactions between the organic and inorganic components. We report on the synthesis of a free-standing, ultrathin (60 μm) SEPM from a solution of lithium polysulfide, phosphorus sulfide, and ethylene sulfide (ES), where the polysulfide triggers the in situ polymerization of ES and the formation of Li3PS4. Reactant ratios were optimized to achieve a room-temperature conductivity of 2 × 10–5 S cm–1. Cryogenic electron microscopy confirmed a uniform nanoscopic distribution of β-Li3PS4 and PES (polyethylene sulfide). This work presents a facile route to the scalable fabrication of ASSBs with promising cycling performance and low electrolyte loading

Covalent Organic Framework Featuring High Iodine Uptake for Li-Ion Battery: Unlocking the Potential of Hazardous Waste

Management of hazardous waste is a pressing global concern, and the battle to ameliorate such waste is far from over, since it is continuously generated by the rapid growth of industrialization and the human population. Simultaneous capture of such hazardous waste and concurrent utilization in a sustainable energy application still remain the ultimate aspiration in the material field due to lack of appropriate methodology and materials from both water and the vapor phase. Herein, a new cost-effective and scalable route has been designed to synthesize a robust covalent organic framework (COF-TCO) that has been employed for iodine sequestration. The resulting adsorbent selectively captures over 98% of a trace amount of I3– from water with an excellent distribution coefficient (Kd ∼ 104 mL/g), revealing a strong affinity toward iodine. The high uptake capacity of 4.92 gg–1 was observed in the vapor phase, and efficient performance was achieved over a wide range of water systems, including potable water, lake water, river water, and seawater. Extensive experimentally guided computational studies revealed ultrahigh iodine selectivity brings out the attendant mechanistic understanding. Importantly, the iodine-captured COF-TCO was utilized for Li-ion battery applications, and it exhibited a modest specific capacity of 120 mAh/g, when tested against a lithium metal anode. The viability of scaling up lithium–iodine batteries for practical energy storage can be aided by hazardous and waste accumulated cathode materials combining safety and sustainability

Thin Solid Electrolyte Layers Enabled by Nanoscopic Polymer Binding

To achieve high-energy all-solid-state batteries (ASSBs), solid-state electrolytes (SE) must be thin, mechanically robust, and possess the ability to form low resistance interfaces with electrode materials. Embedding an inorganic SE into an organic polymer combines the merits of high conductivity and flexibility. However, the performance of such an SE-in-polymer matrix (SEPM) is highly dependent on the microstructure and interactions between the organic and inorganic components. We report on the synthesis of a free-standing, ultrathin (60 μm) SEPM from a solution of lithium polysulfide, phosphorus sulfide, and ethylene sulfide (ES), where the polysulfide triggers the in situ polymerization of ES and the formation of Li3PS4. Reactant ratios were optimized to achieve a room-temperature conductivity of 2 × 10–5 S cm–1. Cryogenic electron microscopy confirmed a uniform nanoscopic distribution of β-Li3PS4 and PES (polyethylene sulfide). This work presents a facile route to the scalable fabrication of ASSBs with promising cycling performance and low electrolyte loading

Covalent Organic Framework Featuring High Iodine Uptake for Li-Ion Battery: Unlocking the Potential of Hazardous Waste

Management of hazardous waste is a pressing global concern, and the battle to ameliorate such waste is far from over, since it is continuously generated by the rapid growth of industrialization and the human population. Simultaneous capture of such hazardous waste and concurrent utilization in a sustainable energy application still remain the ultimate aspiration in the material field due to lack of appropriate methodology and materials from both water and the vapor phase. Herein, a new cost-effective and scalable route has been designed to synthesize a robust covalent organic framework (COF-TCO) that has been employed for iodine sequestration. The resulting adsorbent selectively captures over 98% of a trace amount of I3– from water with an excellent distribution coefficient (Kd ∼ 104 mL/g), revealing a strong affinity toward iodine. The high uptake capacity of 4.92 gg–1 was observed in the vapor phase, and efficient performance was achieved over a wide range of water systems, including potable water, lake water, river water, and seawater. Extensive experimentally guided computational studies revealed ultrahigh iodine selectivity brings out the attendant mechanistic understanding. Importantly, the iodine-captured COF-TCO was utilized for Li-ion battery applications, and it exhibited a modest specific capacity of 120 mAh/g, when tested against a lithium metal anode. The viability of scaling up lithium–iodine batteries for practical energy storage can be aided by hazardous and waste accumulated cathode materials combining safety and sustainability

Selectivity Tailoring in Liquid Phase Oxidation Over MWNT-Mn₃O₄ Nanocomposite Catalysts

Highly selective multiwalled nanotubes (MWNT)-Mn3O4 nanocomposite catalyst was designed for liquid phase oxidation of p-cresol, which gave highest selectivity of 90% to the first step oxidation product, p-hydroxy benzyl alcohol. Mn3O4 nanoparticles and MWNT-Mn3O4 nanocomposites were synthesized by coprecipitation route using mixed precursors under controlled conditions. The phase purity of Mn3O4 and the formation of MWNT-Mn3O4 nanocomposites were confirmed by X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. High-resolution transmission electron microscopy revealed the selective exposure of (101) and (001) planes of Mn3O4 nanoparticles in the MWNT-Mn3O4 composite, while lowering in oxidizing capacity of MWNT-Mn3O4 nanocomposite confirmed by cyclic voltametry was due to incorporation of electron rich MWNT. Thus, selectivity tuning of the new material (MWNT-Mn3O4 nanocomposite) was found to be due to alteration in both geometric as well as electronic properties. A plausible reaction pathway also has been proposed involving the predominant role of nucleophilic lattice oxygen (O2–) species due to exposure of particular crystal planes giving highest selectivity to p-hydroxy benzyl alcohol

Enabling Thin and Flexible Solid-State Composite Electrolytes by the Scalable Solution Process

All solid-state batteries (ASSBs) have the potential to deliver higher energy densities, wider operating temperature range, and improved safety compared with today’s liquid-electrolyte-based batteries. However, of the various solid-state electrolyte (SSE) classespolymers, sulfides, or oxidesnone alone can deliver the combined properties of ionic conductivity, mechanical, and chemical stability needed to address scalability and commercialization challenges. While promising strategies to overcome these include the use of polymer/oxide or sulfide composites, there is still a lack of fundamental understanding between different SSE–polymer–solvent systems and its selection criteria. Here, we isolate various SSE–polymer–solvent systems and study their molecular level interactions by combining various characterization tools. With these findings, we introduce a suitable Li7P3S11SSE–SEBS polymer–xylene solvent combination that significantly reduces SSE thickness (∼50 μm). The SSE–polymer composite displays high room temperature conductivity (0.7 mS cm–1) and good stability with lithium metal by plating and stripping over 2000 h at 1.1 mAh cm–2. This study suggests the importance of understanding fundamental SSE–polymer–solvent interactions and provides a design strategy for scalable production of ASSBs