42 research outputs found
Recent Progress in Electrode Materials for Sodium-Ion Batteries
No full textGrid-scale energy storage systems (ESSs) that can connect to sustainable energy resources have received great attention in an effort to satisfy ever-growing energy demands. Although recent advances in Li-ion battery (LIB) technology have increased the energy density to a level applicable to grid-scale ESSs, the high cost of Li and transition metals have led to a search for lower-cost battery system alternatives. Based on the abundance and accessibility of Na and its similar electrochemistry to the well-established LIB technology, Na-ion batteries (NIBs) have attracted significant attention as an ideal candidate for grid-scale ESSs. Since research on NIB chemistry resurged in 2010, various positive and negative electrode materials have been synthesized and evaluated for NIBs. Nonetheless, studies on NIB chemistry are still in their infancy compared with LIB technology, and further improvements are required in terms of energy, power density, and electrochemical stability for commercialization. Most recent progress on electrode materials for NIBs, including the discovery of new electrode materials and their Na storage mechanisms, is briefly reviewed. In addition, efforts to enhance the electrochemical properties of NIB electrode materials as well as the challenges and perspectives involving these materials are discussed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim12022261sciescopu
Highly Stable Iron- and Manganese-Based Cathodes for Long-Lasting Sodium Rechargeable Batteries
No full textThe development of long-lasting and low-cost rechargeable batteries lies at the heart of the success of large-scale energy storage systems for various applications. Here, we introduce Fe- and Mn-based Na rechargeable battery cathodes that can stably cycle more than 3000 times. The new cathode is based on the solid-solution phases of Na4MnxFe3-x(PO4)(2)-(P2O7) (x = 1 or 2) that we successfully synthesized for the first time. Electrochemical analysis and ex situ structural investigation reveal that the electrodes operate via a one phase reaction upon charging and discharging with a remarkably low volume change of 2.1% for Na4MnFe2(PO4)(P2O7), which is one of the lowest values among Na battery cathodes reported thus far. With merits including an open framework structure and a small volume change, a stable cycle performance up to 3000 cycles can be achieved at 1C and room temperature, and almost 70% of the capacity at C/20 can be obtained at 20C. We believe that these materials are strong competitors for large-scale Na-ion battery cathodes based on their low costs, long-term cycle stability, and high energy density. © 2016 American Chemical Society115141sciescopu
Na3V(PO4)(2) : A New Layered-Type Cathode Material with High Water Stability and Power Capability for Na-Ion Batteries
No full textWe introduce Na3V(PO4)(2) as a new cathode material for Na-ion batteries for the first time. The structure of Na3V(PO4)(2) was determined using X-ray diffraction and Rietveld refinement, and its high water stability was clearly demonstrated. The redox potential of Na3V(PO4)(2) (similar to 3.5 V vs Na/Na+) was shown to be sufficiently high to prevent the side reaction with water (Na extraction and water insertion), ensuring its water stability in ambient air. Na3V(PO4)(2) also exhibited outstanding power capability, with similar to 79% of the theoretical capacity being delivered at 15C. First-principles calculation combined with electrochemical experiments linked this high power capability to the low activation barrier (similar to 433 meV) for the well-interconnected two-dimensional Na diffusion pathway. Moreover, outstanding cyclability of Na3V(PO4)(2) (similar to 70% retention of the initial capacity after 200 cycles) was achieved at a reasonably fast current rate of 1C. © 2018 American Chemical Societ
New 4V-Class and Zero-Strain Cathode Material for Na-Ion Batteries
No full textHere, we introduce Na3V(PO3)(3)N as a novel 4V-class and zero-strain cathode material for Na-ion batteries. Structural analysis based on a combination of neutron and X-ray diffraction (XRD) reveals that the Na3V(PO3)(3)N crystal contains three-dimensional channels that are suitable for facile Na diffusion. The Na (de)intercalation is observed to occur at similar to 4 V vs Na/Na+ in the Na cell via the V3+/V4+ redox reaction with similar to 67% retention of the initial capacity after over 3000 cycles. The remarkable cycle stability is attributed to the near-zero volume change (similar to 0.24%) and unique centrosymmetric distortion that occurs during a cycle despite the large ionic size of Na ions for (de)intercalation, as demonstrated by ex situ XRD analysis and first-principles calculations. We also demonstrate that the Na3V(PO3)(3)N electrode can display outstanding power capability with similar to 84% of the theoretical capacity retained at 10C, even though the particle sizes are on the micrometer scale (> 5 mu m), which is attributed to its intrinsic three-dimensional open-crystal framework. The combination of this high power capability and extraordinary cycle stability makes Na3V(PO3)(3)N a new potential cathode material for Na-ion batteries. © 2017 American Chemical Society5
Lithium-excess olivine electrode for lithium rechargeable batteries
No full textLithium iron phosphate (LFP) has attracted tremendous attention as an electrode material for next-generation lithium-rechargeable battery systems due to the use of low-cost iron and its electrochemical stability. While the lithium diffusion in LFP, the essential property in battery operation, is relatively fast due to the one-dimensional tunnel present in the olivine crystal, the tunnel is inherently vulnerable to the presence of FeLi anti-site defects (Fe ions in Li ion sites), if any, that block the lithium diffusion and lead to inferior performance. Herein, we demonstrate that the kinetic issue arising from the FeLi defects in LFP can be completely eliminated in lithium-excess olivine LFP. The presence of an excess amount of lithium in the Fe ion sites (LiFe) energetically destabilizes the FeLi-related defects, resulting in reducing the amount of Fe defects in the tunnel. Moreover, we observe that the spinodal decomposition barrier is notably reduced in lithium-excess olivine LFP. The presence of LiFe and the absence of FeLi in lithium-excess olivine LFP additionally induce faster kinetics, resulting in an enhanced rate capability and a significantly reduced memory effect. The lithium-excess concept in the electrode crystal brings up unexpected properties for the pristine crystal and offers a novel and interesting approach to enhance the diffusivity and open up additional diffusion paths in solid-state ionic conductors. © 2016 The Royal Society of Chemistry112121sciescopu
Anomalous Jahn-Teller behavior in a manganese-based mixed-phosphate cathode for sodium ion batteries
No full textWe report a 3.8 V manganese-based mixed-phosphate cathode material for applications in sodium rechargeable batteries; i.e., Na4Mn3(PO4)2(P2O7). This material exhibits a largest Mn2+/Mn3+ redox potential of 3.84 V vs. Na+/Na yet reported for a manganese-based cathode, together with the largest energy density of 416 W h kg-1. We describe first-principles calculations and experimental results which show that three-dimensional Na diffusion pathways with low-activation-energy barriers enable the rapid sodium insertion and extraction at various states of charge of the Na4-xMn3(PO4)2(P2O7) electrode (where x = 0, 1, 3). Furthermore, we show that the sodium ion mobility in this crystal structure is not decreased by the structural changes induced by Jahn-Teller distortion (Mn3+), in contrast to most manganese-based electrodes, rather it is increased due to distortion, which opens up sodium diffusion channels. This feature stabilizes the material, providing high cycle stability and high power performance for sodium rechargeable batteries. The high voltage, large energy density, cycle stability and the use of low-cost Mn give Na4Mn3(PO4)2(P2O7) significant potential for applications as a cathode material for large-scale Na-ion batteries. © 2015 The Royal Society of Chemistry140401sciescopu
Effect of the Blade-Coating Conditions on the Electrical and Optical Properties of Transparent Ag Nanowire Electrodes
No full textOptimizing the coating conditions for a doctor blading system is important when seeking to improve the performance of Ag nanowire electrodes. In this study, the effect of the blading height and speed on the optical and electrical properties of Ag nanowire electrodes was investigated. Ag nanowires were first spread on a PET substrate using a doctor blade with differing heights at a fixed blading speed. An increase in the blading height resulted in the degradation of the optical transmittance and stronger haze due to the higher probability of Ag nanowire agglomeration arising from the greater wet thickness. When the blading speed was varied, the optical transmittance and haze were unaffected up until 20 mm/s, followed by minor degradation of the optical properties at blading speeds over 25 mm/s. The higher speeds hindered the spread of the Ag nanowire solution, which also increased the probability of Ag nanowire agglomeration. However, this degradation was less serious compared to that observed with a change in the blading height. Therefore, optimizing the blading height was confirmed to be the priority for the production of high-performance transparent Ag nanowire electrodes. Our study thus provides practical guidance for the fabrication of Ag nanowire electrodes using doctor blading systems
Organic material-derived activated carbon for ecofriendly mulberry paper supercapacitor
No full textPaper has gained increasing attention as promising flexible substrate for deformable energy storage systems. However, since low mechanical strength and chemical resistance of commercial paper limited its practical application, mulberry paper (MP) has alternatively studied, which exhibits high holocellulose content, hydrophilicity, and strong bonding with active material. Herein, we prepared activated carbon (AC) using a one of common waste, orange peel (OP), and coated it on MP with additional coating of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), thereby, fabricating hybrid-coated MP for supercapacitor. The prepared AC exhibited enlarged surface area from 1.774 to 986.010 m2/g, and increased total pore volume of 0.639 cm3/g. Furthermore, additional coating of pseudocapacitive material enhanced electrochemical performance. Specific areal capacitance increased approximately 2.3 times, especially showing 78.95 ± 3.04 mF/cm2 under scan rate of 100 mV/s. Moreover, fabricated electrode exhibited enhanced energy density of 3.01 µW h/cm2 at current density of 0.5 mA/cm2, thereby, complementing low energy density of electric double layer (EDL) capacitive material. This approach, which combines biomass-derived AC and MP with hybrid PEDOT:PSS coating, presents a promising pathway for next-generation sustainable energy storage systems
Pharmacokinetic Interactions Between Bazedoxifene and Cholecalciferol: An Open-Label, Randomized, Crossover Study in Healthy Male Volunteers
No full textMoon Hee Lee,1 Seok-Kyu Yoon,1 Hyungsub Kim,2 Yong-Soon Cho,3 Sungpil Han,4 Shi Hyang Lee,1 Kyun-Seop Bae,1 Jina Jung,5 Sung Hee Hong,5 Hyeong-Seok Lim1 1Department of Clinical Pharmacology and Therapeutics, Asan Medical Center, University of Ulsan, Seoul, Republic of Korea; 2Department of Emergency Medical Services, College of Health Sciences, Eulji University, Seongnam, Republic of Korea; 3Department of Pharmacology and Clinical Pharmacology, Inje University College of Medicine, Busan, Republic of Korea; 4Department of Pharmacology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea; 5Hanmi Pharmaceutical Co. Ltd., Seoul, Republic of KoreaCorrespondence: Hyeong-Seok Lim, Department of Clinical Pharmacology and Therapeutics, Asan Medical Center, University of Ulsan, 88 Olympic-Ro 43-Gil, Songpa-Gu, Seoul, 05505, Republic of Korea, Tel +82-2-3010-4613, Fax +82-2-3010-4623, Email [email protected]: The combined administration of bazedoxifene, a tissue-selective estrogen receptor modulator, and cholecalciferol can be a promising therapeutic option for postmenopausal osteoporosis patients. This study aimed to examine the pharmacokinetic interactions between these two drugs and the tolerability of their combined administration in healthy male subjects.Patients and Methods: Thirty male volunteers were randomly assigned to one of the six sequences comprised of three treatments: bazedoxifene 20 mg monotherapy, cholecalciferol 1600 IU monotherapy, and combined bazedoxifene and cholecalciferol therapy. For each treatment, a single dose of the investigational drug(s) was administered orally, and serial blood samples were collected to measure the plasma concentrations of bazedoxifene and cholecalciferol. Pharmacokinetic parameters were calculated using the non-compartmental method. The point estimate and 90% confidence interval (CI) of the geometric mean ratio (GMR) were obtained to compare the exposures of combined therapy and monotherapy. The pharmacokinetic parameters compared were the maximum plasma concentration (Cmax) and the area under the plasma concentration-time curve from time zero to the last quantifiable concentration (AUClast). The safety and tolerability of the combined therapy were assessed in terms of the frequency and severity of adverse events (AEs).Results: For bazedoxifene, the GMR (90% CI) of the combined therapy to monotherapy was 1.044 (0.9263– 1.1765) for Cmax and 1.1329 (1.0232– 1.2544) for AUClast. For baseline-adjusted cholecalciferol, the GMR (90% CI) of the combined therapy to monotherapy was 0.8543 (0.8005– 0.9117) for Cmax and 0.8056 (0.7445– 0.8717) for AUClast. The frequency of AEs observed was not significantly different between the combined therapy and monotherapy, and their severity was mild in all cases.Conclusion: A mild degree of pharmacokinetic interaction was observed when bazedoxifene and cholecalciferol were administered concomitantly to healthy male volunteers. This combined therapy was well tolerated at the dose levels used in the present study.Keywords: bazedoxifene, cholecalciferol, drug-drug interaction, pharmacokinetics, tolerabilit
Research Trends on the Dispersibility of Carbon Nanotube Suspension with Surfactants in Their Application as Electrodes of Batteries: A Mini-Review
No full textIn the battery field, carbon nanotubes (CNTs) attract much attention due to their potential as a supporting conducting material for anodes or cathodes. The performance of cathodes or anodes can be optimized by introducing densely packed CNTs, which can be achieved with high dispersibility. The efficiency of CNT usage can be maximized by enhancing their dispersibility. An effective technique to this end is to incorporate surfactants on the surface of CNTs. The surfactant produces a surface charge that can increase the zeta potential of CNTs, thereby preventing their agglomeration. Additionally, surfactants having long chains of tail groups can increase the steric hindrance, which also enhances the dispersibility. Notably, the dispersibility of CNTs depends on the type of surfactant. Therefore, the results of dispersibility studies of CNTs involving different surfactants must be comprehensively reviewed to enhance the understanding of the effects of different surfactants on dispersibility. Consequently, this paper discusses the effect of different types of surfactants on the dispersibility of CNTs and presents several perspectives for future research on dispersibility enhancement
