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Hydrogen–bromine redox-flow battery (RFB) technology offers the most economic storage solution and is considered most promising for a sustainable electricity storage solution due to its fast kinetics, highly reversible reactions, and low chemical costs. The main bottleneck of conventional electrodes is the rapid fading of the hydrogen catalyst performance in the highly corrosive environment. Here, we show that a simple coating of the catalyst can effectively protect the catalyst surface from corrosion in concentrated HBr and maintain a high catalytic activity. We polymerize dopamine on the surface of the catalysts and apply a gentle annealing step to obtain a few nanometers thin conformal polydopamine layer, which acts as a semipermeable barrier that effectively blocks Br. The catalytic activity was measured on a glassy carbon rotating disc electrode after dipping in 3 M HBr at 40 °C to accelerate the corrosion. The unprotected catalyst is irreversibly poisoned after 30 min (50% activity loss), while the ...

Sulfur cathodes have excellent theoretical properties for use as positive electrodes in rechargeable lithium batteries, but lack long-term stability required of practical secondary battery systems. To deal with this issue, high capacity Lithium-Sulfur cathodes with extended cycle life were prepared through thermal encapsulation of sulfurat 155°C in disordered micro-porous carbon powders that have high specific surface-area of ~ 2000 m2/g. The electrodes have been characterized using X-ray diffraction (XRD), Scanning electron microscopy/energy-dispersive X-ray (SEM/EDX), Raman spectroscopy, Thermal Gravimetric Analysis (TGA) and Gas adsorption technique. By using microporous carbon as matrices for sulfur cathodes and lithium nitrate as an additive to the electrolyte solution, that suppresses the shuttle phenomena in Li-sulfur batteries, we managed to achieve a reversible capacity of over 500mAh/g after 1000 cycles (Figure 1) with a Columbic efficiency approaching 100% throughout cycling. The sulfur composite cathodes of 14mm in diameter (area of ~1.54 cm2) and active material load of more than 1mg/cm2were tested in a two electrodes configuration with coin-type cells (2523,NRC, Canada). Electrolyte solution was DOL and DME (1:1 ratio) with 10% LiTFSI and 2% of LiNO3(by weight). The influence of the volume of the electrolyte solutions in Li-S cells was further evaluated by analyzing their voltage profiles during cycling.

A new advanced Li-ion battery comprising a high performance amorphous columnar silicon thin film anode, a high voltage LiNi0.5Mn1.5O4 spinel composite cathode and fluoroethylene carbonate (FEC)-based electrolyte solution (FEC/DMC 1:4 with 1 M LiPF6) is reported. This advanced battery demonstrated hundreds of cycles, excellent charge–discharge efficiency and rate capability. Keywords: Silicon anode, LiNi0.5Mn1.5O4, 5 V lithium-ion battery, Fluoroethylene carbonate

lithium-ion cells where cathodes were prepared from the preconditioned with mildly acidic, fluorinated solutions. 7 The cells delivered 170‐188 mAh/g with respect to cathode and exhibited stable cycling during 100 cycles. Further increase in the energy density of the full lithium ion batteries may be obtained by the replacement of the conventional graphite anode by super high capacity lithium alloys. In the present work we report on lithium ion battery in which high capacity cathode is combined with silicon/Li alloy anode which delivers the highest specific capacity in Li batteries. In fully lithiated state, Li4.4Si, this alloy possesses theoretical specific capacity of 4200 mA h g −1 . The capacities reported in the literature 8‐10 are lower (3580 mA h g −1 ) and correspond to a stoichiometry of Li15Si4. Thus, the use of this anode in combination with high capacity Li-rich layered cathode materials xLi2MnO3.(1-x)LiNiyMnzCo1-y-zO2 could provide the highest gravimetric specific capacity ever reached for high voltage lithium ion full cells.

LiFePO4 is one of most promising cathode materials for lithium-ion batteries (LIBs) due to its superior rate handling ability, moderate cost, low environmental hazards, and safe long-term cyclability. In addition to the electrochemical information on the charge and discharge process, electrochemical quartz crystal admittance (EQCA) of LIB electrodes provides direct access to potential-driven frequency shifts (Δfexp) and changes of the resonance peak width (ΔΓ) due to Li-ions insertion/extraction. It is not only possible to monitor mass changes of the electrode, but the two parameters Δfexp and ΔΓ also reflect mechano-structural changes caused by hydrodynamic solid–liquid interactions from the operation of a LIB. Applying a suitable model that takes into account such interactions, potential-induced changes of the effective thickness and permeability of the composite electrode have been determined. The latter shows that ion insertion/extraction results in a nonuniform deformation of the electrode. Using EQC...

Amorphous columnar structured silicon film electrodes were prepared and electrochemically tested in dioxolane based electrolyte solution, containing LiNO3. The electrochemical performance of prelithiated amorphous silicon anodes coupled with sulfur composite cathodes was evaluated in full Si–Li–Sulfur (SLS) cells. The reversible capacity at the first 10 cycles was 600 mAh/g sulfur with gradual fading to ~380 mAh/g sulfur after 60 cycles which is the highest obtained capacity reported for SLS full cells. Possible reasons for this capacity fading are discussed. Keywords: Lithium-ion battery, Vacuum deposited silicon film, Anode, Prelithiated silicon sulfur battery

We propose herein a new reliable approach to assess solvation numbers of ions confined in carbon nanopores based on dynamic quartz crystal measurements. This was proved for the entire families of alkaline, alkaline-earth cations, and halogen anions. As-assessed hydration numbers appear in the sequence characteristic of a transition from the cosmotropic to a chaotropic-type behavior with the decrease of the ion’s charge-to-size ratio. The information on the behavior of ions confined in nanometric space of different (especially charged) carbon materials is in high demand for the development of powerful supercapacitors, nanofiltration membranes, and chemical/biochemical sensors.

The development of Li2S electrodes is a crucial step toward industrial manufacturing of Li-S batteries, a promising alternative to Li-ion batteries due to their projected two times higher specific capacity. However, the high voltages needed to activate Li2S electrodes, and the consequent electrolyte solution degradation, represent the main challenge. We present a novel concept that could make feasible the widespread application of Li2S electrodes for Li-S cell assembly. In this concept, the addition of redox mediators as additives to the standard electrolyte solution allows us to recover most of Li2S theoretical capacity in the activation cycle at potentials as low as 2.9 VLi, substantially lower than the typical potentials >4 VLi needed with standard electrolyte solution. Those novel additives permit us to preserve the electrolyte solution from being degraded, allowing us to achieve capacity as high as 500 mAhg(-1)Li2S after 150 cycles with no major structural optimization of the electrodes.

A route for the preparation of binder-free sulfur-carbon cathodes is developed for lithium sulfur batteries. The method is based on the impregnation of elemental sulfur into the micropores of activated carbon fibers. These electrodes demonstrate good electrochemical performance at high current density attributed to the uniform dispersion of sulfur inside the carbon fiber.

Conventional redox flow batteries (RFB) use electrolyte solutions as energy storage media. For this reason the energy density is mainly limited by the solubility of the redox couples in the solutions. The kinetics of the reactions is mostly moderate so that cycling power densities can only reach max. 100 mW/cm². Depending on the energy / performance ratio the cost of the energy converter of RFBs clearly dominates the total investment costs. For longer storage periods the influence of the cost of the energy storage medium increases. For these reasons RFBs with redox pairs with high kinetics and thus a high power density are desirable. Hydrogen and bromine-based energy storage fulfill both requirements because the kinetics of the reactions are very fast and both elements are inexpensive and very abundant. In addition potentially high energy densities and efficiencies can be achieved. Anode: H2 -> 2 H+ +2 e- E0 = 0.00 V Cathode: Br2 +2 e- -> 2 Br- E0 = + 1.06 V Cell: H2 + Br2 -> 2 HBr E = 1.06 V Although the first studies were made in the 80s of the last century [1], the research intensified due to these positive characteristics in the last years [2, 3]. For a viable use, hydrogen storage, bromine diffusion, bromine complexation and system behavior are the biggest challenges. In this work we want to present the results of the development and the construction of an H/Br-RFB with an active area of 40 cm² and its behavior at different electrolyte compositions, temperatures and current densities. For better identification of the properties the half-cell potentials and impedances were also measured and evaluated. This research forms the basis for our future studies involving the use of advanced bromine complexation agents (BCAs) and their impact on H/Br-RFB. [1] Yeo, R. S.; Chin, D. ‐T. (1980): A Hydrogen‐Bromine Cell for Energy Storage Applications. In: Journal of The Electrochemical Society 127 (3), S. 549–555. DOI: 10.1149/1.2129710. [2] Cho, Kyu Taek; Albertus, Paul; Battaglia, Vincent; Kojic, Aleksandar; Srinivasan, Venkat; Weber, Adam Z. (2013): Optimization and Analysis of High-Power Hydrogen/Bromine-Flow Batteries for Grid-Scale Energy Storage. In: Energy Technology 1 (10), S. 596–608. DOI: 10.1002/ente.201300108. [3] Cho, Kyu Taek; Tucker, Michael C.; Ding, Markus; Ridgway, Paul; Battaglia, Vincent S.; Srinivasan, Venkat; Weber, Adam Z. (2014): Cyclic Performance Analysis of Hydrogen/Bromine Flow Batteries for Grid-Scale Energy Storage. In: ChemPlusChem, S. n/a. DOI: 10.1002/cplu.201402043. Figure 1

Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009

Li-ion battery technology has become very important in recent years as these batteries show great promise as power sources that can lead us to the electric vehicle (EV) revolution. The development of new materials for Li-ion batteries is the focus of research in prominent groups in the field of materials science throughout the world. Li-ion batteries can be considered to be the most impressive success story of modern electrochemistry in the last two decades. They power most of today's portable devices, and seem to overcome the psychological barriers against the use of such high energy density devices on a larger scale for more demanding applications, such as EV. Since this field is advancing rapidly and attracting an increasing number of researchers, it is important to provide current and timely updates of this constantly changing technology. In this review, we describe the key aspects of Li-ion batteries: the basic science behind their operation, the most relevant components, anodes, cathodes, electrolyte solutions, as well as important future directions for R&D of advanced Li-ion batteries for demanding use, such as EV and load-leveling applications.

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In this work, structural and morphological changes in composite sulfur electrodes were studied due to their cycling in rechargeable Li-S cells produced by Sion Power Inc. Composite sulfur cathodes, comprising initially elemental sulfur and carbon, undergo pronounced structural and morphological changes during discharge-charge cycles due to the complicated redox behavior of sulfur in nonaqueous electrolyte solutions that contain Li ions. Nevertheless, Li―S cells can demonstrate prolonged cycling. To advance this technology, it is highly important to understand the evolution of the structure and morphology of sulfur cathodes as cycling proceeds. High resolution scanning and tunneling microscopy, scanning probe microscopy, and Raman spectroscopy were used in conjunction with the electrochemical measurements. A special methodology for slicing composite sulfur electrodes and their cross sectioning and depth profiling was developed. The gradual changes in the structure of sulfur cathodes due to cycling is described and discussed herein. Important phenomena include changes in the surface electrical conductivity of sulfur electrodes and pronounced morphological changes due to the irreversibility of the sulfur redox reactions. Based on the observations presented in this work, it may be possible to outline guidelines for improving Li-S battery technology and extending its cycle life.

Li(metal)-sulfur (Li-S) systems are among the rechargeable batteries of the highest possible energy density due to the high capacity of both electrodes. The surface chemistry developed on Li electrodes in electrolyte solutions for Li-S batteries was rigorously studied using Fourier transform infrared and X-ray photoelectron spectroscopies. A special methodology was developed for handling the highly reactive Li samples. It was possible to analyze the contribution of solvents such as 1-3 dioxolane, the electrolyte LiN(SO 2 CF 3 ) 2 , polysulfide (Li 2 S n ), and LiNO 3 additives to protective surface films that are formed on the Li electrodes. The role of LiNO 3 as a critical component whose presence in solutions prevents a shuttle mechanism that limits the capacity of the sulfur electrodes is discussed and explained herein.