Inactive Components Research Articles

Analysis of Exchange Power in the Power System of Drone

The classification of drones - both military and civilian according to the relevant criteria - is presented. Block diagrams of a typical unmanned aerial vehicle and its power system are shown. Typically, a drone power system of the "micro", "mini" or "short range" category, according to the UVS international classification, is a set of DC / DC converters with a microprocessor control system. The power source for such aircraft is usually a battery, less often - fuel cells. During the flight, the engine speed is variable, and its change depends not only on changes in flight speed or direction, but also on weather conditions, such as wind, as the stabilization system constantly aligns the drone. This leads to the fact that the power supply system of such a device is actually a significant part of the time in transition condition. This leads to a significant content of the component of exchange energy that battery consumed which in turn will increase losses, and thus reduces the range of the unmanned aerial vehicle. The phenomenon of the occurrence of exchange power in the power supply systems of electric vehicles which powered from DC sources and specifically in the power supply system of an unmanned aerial vehicle is analyzed. The time diagrams of current, voltage, active and inactive components of power consumed from the mains power supply network of electric locomotive DE1 are illustrated. It can be seen that with a sharp change in the modes of operation of traction units there is a significant component of exchange power in the motor-network system. Such processes are typical for almost any electric vehicle and are associated with the presence of a significant number of reactive elements in the power supply systems, as well as frequent changes in load parameters. A block diagram of a typical unmanned aerial vehicle is presented. The unmanned aerial vehicle system consists of three parts: the air part, the unmanned aerial vehicle itself, the ground control station, which can be autonomous or manned, the control system, which provides communication and data transmission. The block diagram of the power system of a typical unmanned aerial vehicle is presented A simplified schematic diagram of the DC motor power supply system is presented. The relations for determining the amount of exchange power in the power supply system of an unmanned aerial vehicle are derived. It is concluded that to reduce the impact of this phenomenon, it is necessary to modify the power supply system by adding compensation units of inactive power component.

Macro‐ and Nano‐Porous 3D‐Hierarchical Carbon Lattices for Extraordinarily High Capacitance Supercapacitors

AbstractSupercapacitors, which can be charged/discharged rapidly, play important roles in a sustainable society. Thick electrodes can reduce the ratio of inactive components in the overall cell while simultaneously improving energy and power densities. However, thick electrodes induce longer ion diffusion pathways, and capacitance drops dramatically after a certain thickness. To overcome this, precisely designed macro‐ and nano‐porous 3D‐hierarchical carbon lattices, where ions can diffuse freely inside the electrode, are prepared by combining an inexpensive stereolithography‐type 3D printer, whose resolution is 50 µm, with a simple CO2 activation process. The activated 3D carbon lattice with a 66% burn‐off ratio (3D‐CL‐A66%) has ordered macropores (≈150 µm) and uniform nanopores (2–3 nm), exhibiting a maximum areal capacitance of 5251 mF cm–2 at 3 mA cm–2. Furthermore, manganese oxide is electrochemically deposited on 3D‐CL‐A16% for 8 min (3D‐CL‐A16%‐MnO2‐8 min), increasing the areal capacitance by 2.5‐times. Finally, an all‐3D‐printed asymmetric 1.8 V supercapacitor is prepared by combining 3D‐CL‐A16%‐MnO2‐8 min and 3D‐CL‐A66% as the positive and negative electrodes, respectively, demonstrating a maximum energy density of 0.808 mWh cm–2 at a power density of 2.48 mW cm–2. The achieved values are one of the highest areal energy and power densities reported so far.

3D Correlative Imaging of Lithium Ion Concentration in a Vertically Oriented Electrode Microstructure with a Density Gradient.

The performance of Li+ ion batteries (LIBs) is hindered by steep Li+ ion concentration gradients in the electrodes. Although thick electrodes (≥300 µm) have the potential for reducing the proportion of inactive components inside LIBs and increasing battery energy density, the Li+ ion concentration gradient problem is exacerbated. Most understanding of Li+ ion diffusion in the electrodes is based on computational modeling because of the low atomic number (Z) of Li. There are few experimental methods to visualize Li+ ion concentration distribution of the electrode within a battery of typical configurations, for example, coin cells with stainless steel casing. Here, for the first time, an interrupted in situ correlative imaging technique is developed, combining novel, full‐field X‐ray Compton scattering imaging with X‐ray computed tomography that allows 3D pixel‐by‐pixel mapping of both Li+ stoichiometry and electrode microstructure of a LiNi0.8Mn0.1Co0.1O2 cathode to correlate the chemical and physical properties of the electrode inside a working coin cell battery. An electrode microstructure containing vertically oriented pore arrays and a density gradient is fabricated. It is shown how the designed electrode microstructure improves Li+ ion diffusivity, homogenizes Li+ ion concentration through the ultra‐thick electrode (1 mm), and improves utilization of electrode active materials.

DFT Simulation of Cortisone-Fullerenol Agents in the Therapy of Oncological Diseases

In order to therapeutically destroy oncological neoplasms chemotherapy or radiotherapy is usually applied, and in isotope medicine short-lived radionuclides are injected into the tumor (59Fe, 90Y, 95Zr, 99mTc, 106Ru, 114mIn, 147;148;155Eu, 170Tm, 188Re, 210Po, 222Rn, 230U, 237Pu, 240;241Cm, 253Es). Binary (or neutron-capture) is a technology developed for a selective effect on malignant neoplasms and using drugs tropic to tumors containing nonradioactive nuclides (10B, 113Cd, 157Gd etc.). Triadic is the sequential introduction into the body of a combination of two or more separately inactive and harmless components, tropic to tumor tissues and capable of selectively accumulating in them or entering into chemical interaction with each other and destroying tumor neoplasms under the influence of certain sensitizing external influences. The aim of this work is quantum-chemical simulation of the electronic structure and analysis of the thermodynamic stability of new cortisone-fullerenol agents for the treatment of tumor neoplasms. The need for preliminary studies of modeling such objects is due to the very high labor intensity, cost and complexity of their practical production.

Hierarchical Ion/Electron Networks Enable Efficient Red Phosphorus Anode with High Mass Loading for Sodium Ion Batteries

AbstractRed phosphorus (RP), with high theoretical specific capacity and low working potential, has been regarded as one of the most promising anodes for high‐performance sodium‐ion batteries (SIBs). However, the unsatisfactory performance of RP anodes especially under high mass loading conditions severely limited the development for practical applications, due to its large volume variations during cycling processes, and the poor electronic and ionic conductivity. Here, a hierarchical WDC/CNTs@RP electrode with high mass loadings of RP (up to 14.1 mg cm−2) and superior conductivity is rationally designed for both ions and electrons. Such unique hierarchical structures enable an unprecedented rate performance (1.63 mAh cm−2 under 106.6 mA cm−2), long cycling life, and a decent gravimetric capacity of 468.88 mA h g−1 based on the whole electrode and inactive components. This work presents an essential step toward practical applications of RP anode materials for SIBs batteries.

Spinel-related Li2Ni0.5Mn1.5O4 cathode for 5-V anode-free lithium metal batteries

The anode-free lithium metal battery with high voltage LiNi0.5Mn1.5O4 cathode is an excellent Co-free high energy density (ED) system. However, it suffers severely from cycling capacity fading due to no lithium compensation from the anode side. In this study, as against LiNi0.5Mn1.5O4 cathode, Li-rich Li2Ni0.5Mn1.5O4 is proposed, which can smoothly convert into LiNi0.5Mn1.5O4 and release a large amount of Li-ions at the first charge to replace the Li loss in the following cycle, thereby extending the lifespan of the battery without the introduction of inactive components. Using such a Li-rich cathode, the anode-free pouch cell attained 367-Wh kg−1 stack ED and 88% capacity retention (CR) after 50 cycles, with limited electrolyte addition (E/C ratio of 2 g Ah−1). Our work provides a new low-cost strategy to explore high ED Co-free Li metal batteries.

Screening and identification of acetylcholinesterase inhibitors from Terminalia chebula fruits by immobilized enzyme on cellulose filter paper coupled with ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry and molecular docking

With the increasing demand of new drugs for the treatment of Alzheimer's disease (AD), screening acetylcholinesterase (AChE) inhibitors from traditional Chinese medicines (TCMs) has been proved to be an effective strategy for drug discovery. In present study, a novel strategy was developed to fish out AChE inhibitors from Terminalia chebula fruits based on immobilized AChE coupled with ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) and molecular docking. For AChE immobilization, cellulose filter paper (CFP) as the carrier was modified with chitosan to be introduced to amino groups, and then AChE was modified on the amino-modified CFP through a Schiff base reaction with glutaraldehyde as a cross-linking agent. The CPF-immobilized AChE possessed advantages of a wider range for pH and temperature endurance, better storage stability, excellent reproducibility and reusability. The CPF-immobilized AChE was incubated with the extract of T. chebula fruits, and then the active components would form complexes with immobilized AChE. The complexes were further conveniently separated with inactive components by virtue of the instantaneous separation characteristic of CFP. Eventually, 25 (1–11, 13–26) potential AChE inhibitors were fished out and their structures were further identified by UPLC-QTOF-MS. Moreover, molecular docking was performed to discriminate non-specific compounds to AChE and explore binding mechanisms between potential inhibitors and AChE, and 25 compounds could be well embedded into active sites of AChE with affinities ranging from -9.9 to -6.4 kcal/mol. Inhibitory activities of screened active components on AChE were evaluated in vitro, and punicalagin, 1,3,6-tri-O-galloyl-β-D-glucose (1,3,6-TGG), chebulinic acid and geraniin exhibited excellent AChE-inhibitory properties with IC50 values of 0.43 ± 0.03, 0.46 ± 0.02, 0.50 ± 0.03 and 0.51 ± 0.03 mM, respectively. The results indicated that the developed method was simple and efficient, and could be utilized to screen and identify potential AChE inhibitors from TCMs.

Semiochemical signatures associated with differential attraction of Anopheles gambiae to human feet.

BackgroundSeveral human-produced volatiles have been reported to mediate the host-seeking process under laboratory conditions, yet no effective lure or repellent has been developed for field application. Previously, we found a gradation of the attractiveness of foot odors of different malaria free individuals to Anopheles gambiae sensu stricto Giles. In this study, foot odor of the individual with the most attractive ‘smelly’ feet to the An. gambiae was collected, analyzed and attractive blend components identified.MethodsThe foot odor of the individual with the most attractive ‘smelly’ feet to the An. gambiae was trapped on Porapak Q and analyzed by gas chromatography-linked mass spectrometry (GC-MS). Specific constituents perceived by the insect olfactory system were then identified by GC-linked to electro-antennography detector (GC-EAD) and characterized by GC-MS. The contribution of each constituent to the behavioral response of An. gambiae was assessed through subtractive assays under semi-field conditions in a screen-house using Counter Flow Geometry (CFG traps) baited with (i) the blend of all the EAD-active and (ii) other blends containing all components with exclusion of one component at a time. The number of mosquitoes trapped in the baited CFG traps were compared with those in the control traps.ResultsEleven major and minor constituents: 2 carboxylic acids, six aldehydes, two ketones and one phenolic compound, were confirmed to be EAD-active. The contribution of each constituent to the behavioral response of An. gambiae was assessed through subtractive assays under semi- field conditions. Exclusion/ subtraction of one of the following compounds: i-butyric acid, i-valeric acid, n-octanal, n-nonanal, n-decanal, n-dodecanal, undecanal or n-tridecanal, from each blend led to reduction in the attractiveness of all the resulting blends, suggesting that all of them are critical/important for the attractiveness of the foot odor to An. gambiae mosquitoes. However, exclusion/subtraction of 4-ethoxyacetophenone, 4-ethylacetophenone and/or 2-methylphenol, led to significant enhancements in the attractiveness of the resulting blends, suggesting that each of these compounds had repellent effect on An. gambiae ss. Undecanal exhibited kairomonal activity at low natural concentrations under semi-field conditions but repellent activity at high unnatural conditions in the laboratory. Furthermore, the comparison of the mean mosquito catches in traps baited with the nine-component blend without 4-ethoxyacetophenone, 4-ethylacetophenone and the complete foot odor collection revealed that the former is significantly more attractive and confirmed the repellent effect of the two carbonyl compounds at low natural concentration levels.ConclusionThese results suggest that differential attractiveness of An. gambiae to human feet is due to qualitative and/or qualitative differences in the chemical compositions of the foot odors from individual human beings and relative proportions of the two chemical signatures (attractants versus repellents) as observed from the ratios of the bioactive components in the foot odors of the most attractive and least attractive individuals. Chemical signature means the ensemble of the compounds released by the organism in a specific physiological state. The chemical signature is emitter-dependent, but does not depend on receiver response. Thus, there is only one chemical signature for one individual or species that may eventually include inactive, attractive and repellent components for another organism. The nine-component attractive blend has a potential as an effective field bait for trapping of malaria vectors in human dwellings.

Quantum-chemical modeling of cortisone-fullerenol agents of cancer therapy

In order to therapeutically destroy oncological neoplasms, chemotherapy or radiotherapy is usually applied, and in isotope medicine – short-lived radio nuclides are injected into the tumor (59Fe, 90Y, 95Zr, 99mTc, 106Ru, 114*In, 147Eu, 148Eu, 155Eu, 170Tm, 188Re, 210Po, 222Rn, 230U, 237Pu, 240Cm, 241Cm, 253Es). Binary (or neutron capture) therapy is a technology developed for the selective effect on malignant tumors using drugs that are tropic to tumors and contain non-radioactive nuclides (10B, 113Cd, 157Gd at al.). Triadic therapy involves the sequential introduction into the body of a combination of two or more separately inactive and harmless components, which are tropic to tumor tissues and capable of selectively accumulating in them or chemically interacting with each other and destroying tumor neoplasms under the action of certain sensitizing external influences. The aim of this work is quantum-chemical simulation of the electronic structure and analysis of the thermodynamic stability of new cortisone-fullerenol agents for the treatment of tumor neoplasms. The need for preliminary studies of modeling such objects is due to the very high labor intensity, cost and complexity of their practical production.

Impact of secondary particle size and two-layer architectures on the high-rate performance of thick electrodes in lithium-ion battery pouch cells

Increasing lithium-ion battery gravimetric energy density to > 300 Wh/kg, while simultaneously meeting a cost target of $80/kWh, is of paramount importance to increasing the driving range and affordability of electric vehicles. One way to address this goal is to reduce inactive components by increasing electrode areal capacities, but conventional thick electrode designs typically perform poorly at high discharge rates due to Li + mass transport limitations. Here we compare the rate capability and cycle life of NMC 532/graphite pouch cells made with five different thick cathode and anode designs paired together in 25 combinations. We find that using different particle sizes to structure both the cathode and anode architectures in two-layer configurations results in a 2X capacity improvement over the worst-performing combination at high discharge rates (97 vs. 46 mAh/g at 2C). These different cathode/anode designs also translate to different cycle life performance, with many cells cycled at C/2 achieving ∼80% capacity retention after 1000 cycles, and cells cycled at 2C showing different degrees of capacity fade. Overall, these results demonstrate that simple, scalable changes in electrode design can significantly improve the performance of thick electrodes for high energy density batteries. • Compared rate capability of pouch cells w/different thick cathode & anode designs. • Simple two-layer designs w/different particle sizes can be easily scaled up. • Pairing a two-layer cathode & a two-layer anode gave 2X capacity improvement at 2C. • Particle size & configuration both play important roles in determining performance. • Several electrode designs showed ≥80% capacity retention after 1000 cycles at C/2.

Understanding the Role of π-Conjugated Polymers as Binders in Enabling Designs for High-Energy/High-Rate Lithium Metal Batteries

Developing lithium-ion batteries with both high specific energy and high-power capability is a challenging task because of the necessity for meeting conflicting design requirements. We show that high-energy and high-rate capability can be achieved by using various π-conjugated p-dopable polymers as binders at the cathode and by lowering the mass fraction of all the inactive components of the cell. We report a lithium-metal battery that can deliver 320 Wh kg−1 at C/2 using a mass-efficient cell design. To this end, three conducting polymers with different ionic and electronic conductivities have been studied; dihexyl-substituted poly(3,4-propylenedioxythiophene) (PProDOT-Hx2), poly(3-hexylthiophene) (P3HT), and a new Random Copolymer (Hex:OE)(80:20) PProDOT. These conducting polymers are compared against a conventional polymer binder, PVDF. We show that under the mass-efficient conditions required for achieving high specific energy and rate capability, the conducting polymers play a crucial role by providing electronic and ionic conductivity, protection against rapid growth of solid electrolyte interphase (SEI), and access to a large electrochemically active surface area. Thus, the use of conducting polymers with appropriate molecular structure as binders opens a viable pathway to maximizing the specific energy and rate capability of lithium-ion battery cathodes.

Comprehensive Insights into the Porosity of Lithium-Ion Battery Electrodes: A Comparative Study on Positive Electrodes Based on LiNi0.6Mn0.2Co0.2O2 (NMC622)

Porosity is frequently specified as only a value to describe the microstructure of a battery electrode. However, porosity is a key parameter for the battery electrode performance and mechanical properties such as adhesion and structural electrode integrity during charge/discharge cycling. This study illustrates the importance of using more than one method to describe the electrode microstructure of LiNi0.6Mn0.2Co0.2O2 (NMC622)-based positive electrodes. A correlative approach, from simple thickness measurements to tomography and segmentation, allowed deciphering the true porous electrode structure and to comprehend the advantages and inaccuracies of each of the analytical techniques. Herein, positive electrodes were calendered from a porosity of 44–18% to cover a wide range of electrode microstructures in state-of-the-art lithium-ion batteries. Especially highly densified electrodes cannot simply be described by a close packing of active and inactive material components, since a considerable amount of active material particles crack due to the intense calendering process. Therefore, a digital 3D model was created based on tomography data and simulation of the inactive material, which allowed the investigation of the complete pore network. For lithium-ion batteries, the results of the mercury intrusion experiments in combination with gas physisorption/pycnometry experiments provide comprehensive insight into the microstructure of positive electrodes.

Optimization of AEM Electrolyzer Anodes Leading to High Performance and Durability

Anion Exchange Membrane Water Electrolyzers (AEMWEs) have received a significant amount of attention in recent years. It is believed that AEMWEs have the ability to combine the advantages of traditional alkaline electrolyzers (low cost materials) with Proton Exchange Membrane Electrolyzers (high current density, facile pressurization). However, many of the AEMWEs reported in the literature have shown limited performance and longevity. It is known that the properties of the active materials (e.g. catalyst and membranes) themselves can have an impact on the AEMWE performance. However, less has been presented in the literature regarding the composition of the electrode. In addition, very few studies have dealt with the influence of inactive components, such as the gas diffusion layer.Therefore, in this presentation, the effects of catalyst loading, catalyst chemistry, gas diffusion layer (GDL) type and inclusion of a conductive additive will be discussed. The influence of each factor will be elucidated through a two-stage Design of Experiments (DoE) approach with a full statistical analysis. Such an analysis allows for the rational design of future generations of the anode electrode, including predictions for output voltage response. In the first stage of the DoE, a 24 factorial experiment matrix was designed (four factors at two levels). In the second stage, two factors are analyzed with 4 levels to better resolve their dynamic effects on performance. Finally, the knowledge gained is used to assemble a AEMWE that is able to operate stably for a continuous 720 hours (30 days).

Operando Visualization of Utilization within Functioning Battery Electrodes

Adoption of thick electrode configurations can increase the overall systems level energy density of future batteries by minimizing inactive components such as metal foils and separator layers. However, simply increasing the activematerial in the electrode does not translate to full utilization and delivery of a stable capacity over extended cycling. Thus, it is necessary to have understanding of electron transfer and ion transport, ideally with spatial and temporal resolution, to enable the rational design of larger scale systems with high energy density. A specific benefit of energy dispersive x-ray diffraction in conjunction with a synchrotron light source is the ability to measure intact stainless steel housing electrochemical cells, preventing any artifacts due to the use of cell windows, removal of the electrodes, or any post-treatment methods used in the cell disassembly process. Further, the ability to collect x-ray data real time concurrently with the electrochemical activity provides insight into the kinetics of the electrochemistry under usage conditions. The application of this technique to determine phase localization and rationalize electrode utilization will be highlighted in this presentation.

Thick Sintered Electrodes with Porosity Gradients to Facilitate Ion Transport

Engineering electrode structure such as increasing thickness increases areal energy density and reduces the relative mass and volume allocated to inactive components. However, electrodes with increased thickness encounter ionic and/or electronic transport limitations at high rates of charge/discharge. This poster will describe an investigation of electrodes with porosity gradients. Sintered electrodes were used due to the ability to fabricate relatively thick electrodes using only solid electroactive materials and mild sintering processing. Larger porosity near the separator facilitated ionic transport because this region has greater ion flux relative to regions near the current collector, particularly at high current densities where overall electrode utilization is more restricted to the separator region for both electrodes. A gradient structure would also be desirable because reduced porosity next to the current collector will increase overall cell energy density at lower rates when ion transport restrictions are less of an issue. We will present the experimental and simulation comparisons between electrodes with gradients in porosity, where for comparison the higher porosity is near the separator or current collector region. Electrodes with equivalent total porosity without a gradient structure were investigated as controls.

Modeling Current Density Non-Uniformity to Detect Premature Failure in 3D Lithium-Ion Batteries

Conventional Lithium-ion (Li-ion) intercalation batteries that are composed of planar cathode, separator, and anode layers bear an intrinsic trade-off between energy density and power density. While thick electrodes allow for more active material loading and higher energy densities, thick electrodes lengthen ion transport pathways and limit power and fast charging performance. Conversely, thin electrodes have fast ion transport at the cost of reduced material loading which leads to lower energy densities. Due to the high weight and volume ratio of inactive components, stacking layers of thin planar batteries is inefficient for high capacity cells.1 Three-dimensional (3D) batteries decouple the power-energy trade-off in planar batteries by modifying electrode architecture on a micron to millimeter scale.2 3D batteries redistribute electrode material beyond planar geometry to controlled 3D spatial arrangements in pursuance of shorter ion-transport pathways and enhanced fast charging behavior in a battery cell. This enables high power performance without sacrificing the mass of active material in the cell, and ideally maintains high energy and power performance at high discharge and charge rates. However, a known issue in 3D batteries is the inhomogeneous transport distances between electrodes leading to nonuniform current density and local depletion of the electrode or electrolyte material.3,4 These nonuniformities can terminate a discharge or charge cycle prematurely. Although many 3D batteries have been proposed to date, few comparative modeling studies have been conducted for these architectures to understand their relative performance gains.In this work, we adapt a two-dimensional current density uniformity index (UI) measure from previous work5 and investigate its usage as a potential 3D metric for quantifying premature failure in 3D batteries. A series of 3D batteries are simulated using the software AMPERES that models a 3D electrochemical systems at the continuum level using volume-averaging techniques.6 Two material models – LiFePO4 (LFP) | Li4Ti5O12 (LTO) and LiNi0.5Mn0.3Co0.2O2 (NMC532) | Graphite – are investigated for each 3D battery architecture. We also visualize 3D Li-ion concentration profiles and Li-ion transport pathways to qualitatively analyze the transport behavior in each 3D battery. Our results show that 3D battery performance is material dependent, and 3D batteries with premature depletion demonstrate high UI metrics early in a discharge cycle. References C. L. Cobb and S. E. Solberg, J. Electrochem. Soc., 164, A1339–A1341 (2017).C. L. Cobb and M. Blanco, Journal of Power Sources, 249, 357–366 (2014).R. Hart, H. White, B. Dunn, and D. Rolison, Electrochemistry Communications, 5, 120–123 (2003).A. A. Talin, D. Ruzmetov, A. Kolmakov, K. McKelvey, N. Ware, F. El Gabaly, B. Dunn, and H. S. White, ACS Appl. Mater. Interfaces, 8, 32385–32391 (2016).D. Grazioli, V. Zadin, D. Brandell, and A. Simone, Electrochimica Acta, 296, 1142–1162 (2019).S. Allu, S. Kalnaus, S. Simunovic, J. Nanda, J.A. Turner, and S. Pannala, Journal of Power Sources, 325, 42–50 (2016). Acknowledgements This work was funded in part by a Defense Advanced Research Projects Agency (DARPA) Young Faculty Award under grant number D19AP00038. The views, opinions, and/or findings expressed are those of the authors and should not be interpreted as representing the official views or policies of the Department of Defense or the U.S. Government.

Secondary Bonding Channel Design Induces Intercalation Pseudocapacitance toward Ultrahigh-Capacity and High-Rate Organic Electrodes.

Organic electrode materials have shown extraordinary promise for green and sustainable electrochemical energy storage devices, but usually suffer from low specific capacity and poor rate capability, which is largely caused by inactive components and diffusion-controlled Li+ intercalation. Herein, high-rate Li+ intercalation pseudocapacitance in organic molecular crystals is achieved through introducing weak secondary bonding channels, far exceeding their theoretical capacity based on redox chemistry at functional groups. The authors' combined experimentally electrochemical characterization with first-principles calculations show that the heterocyclic organic molecule 2,2'-bipyridine-4,4'-dicarboxylic acid (BPDCA) crystal permits a four-electron redox reaction at conventional CO and CN groups and a six-electron intercalation pseudocapacitance along conjugated alkene hydrogen bonding channels (H2 NC5 H⋯OC(OH)) and heterocyclic aromatic stacking channels (C5 H3 N⋯NH3 C5 ). The BPDCA electrode delivers an ultrahigh reversible capacity of 1206mAhg-1 at 0.5Ag-1 and an exceptional rate capability. A 4.8V high-energy/power-density BPDCA anode-based hybrid Li-ion capacitor is thus realized. This work opens a new avenue for developing organic intercalation pseudocapacitive materials via secondary bonding structure design.

Probing Sulfur Deposition onto Carbon Nanomaterials from Aqueous, Elemental Sulfur Sols for Lithium-Sulfur Batteries.

Sulfur cathodes for lithium-sulfur batteries often rely on integrating sulfur with high surface area carbonaceous materials. Nanoscale mixing is typically achieved by a lengthy, high-temperature melt imbibition approach that employs carbon nanomaterials in an aggregated solid form. In this work, we present a simple strategy to coat carbon nanomaterials with sulfur in a cost-effective, room-temperature process using inexpensive elemental sulfur. Our results are based on hydrophobic sulfur sols, which have rarely been examined for use in the preparation of sulfur cathodes. We study the deposition mechanism on different carbon materials and find that sulfur dissolves from the sol into the aqueous phase and coats the surface of reduced graphene oxide (rGO) by heterogeneous nucleation and growth, but that this mechanism is not favored for carbon materials such as Ketjen black (KB) and graphene oxide (GO), for which undesirable homogeneous nucleation of micron-sized, insulating sulfur crystals is observed. High loading (3-4 mgsulfur/cm2) rGO-based cathodes prepared using this approach achieve discharge capacities of 1300 mAh/gsulfur (∼4.8 mAh/cm2) at 0.1C and achieve capacities 7-fold higher than cells prepared via traditional melt imbibition approaches at higher rates of 0.8C and 1C. Cells prepared without the need for added binder or conductive additive achieve projected full cell energy densities of 468 Wh/kg at 0.1C when taking into account all inactive components and assuming no lithium metal degradation, indicating that the deposition of sulfur from hydrophobic sols onto carbon nanomaterials can serve as a simple, aqueous-based, one-step process to prepare high sulfur loading cathodes with high projected energy densities.

Emergence of Ni-Based Chalcogenides (S and Se) for Clean Energy Conversion and Storage.

Nickel chalcogenide (S and Se) based nanostructures intrigued scientists for some time as materials for energy conversion and storage systems. Interest in these materials is due to their good electrochemical stability, eco-friendly nature, and low cost. The present review compiles recent progress in the area of nickel-(S and Se)-based materials by providing a comprehensive summary of their structural and chemical features and performance. Improving properties of the materials, such as electrical conductivity and surface characteristics (surface area and morphology), through strategies like nano-structuring and hybridization, are systematically discussed. The interaction of the materials with electrolytes, other electro-active materials, and inactive components are analyzed to understand their effects on the performance of energy conversion and storage devices. Finally, outstanding challenges and possible solutions are briefly presented with some perspectives toward the future development of these materials for energy-oriented devices with high performance.

Cross-aligned carbon nanofibrous network for efficient and outstanding high-rate Li storage capability

The conventional use of metallic current collector in an electrochemical cell results in decreased loading of active materials and hence limited capacity in consideration of all the inactive current collector components. In response to this trend, a number of conductive, free-standing materials have been proposed as electrodes, which would act as both current collector and active materials. Here, in this study, we have firstly developed the cross-aligned carbon nanofiber (CA-CNF) for efficient Li storage, especially at high current densities. Using the insulating block electrospinning, the nanofibers can be aligned in a certain direction, where it is viable to fabricate cross-aligned nanofibers in a cost-effective and scalable manner. Attributed to faster kinetics and regular electron pathway arising from CA-CNF, it exhibits an excellent high-rate cyclability (259.4 mAh g−1 at a current density of 3000 mA g−1). This work builds up a milestone in suggesting a cross-aligned carbon nanofibrous network as efficient Li storage, which can also be applied to various electrode materials embedded cross-aligned conductive composite materials.