Results 1 - 10 of 95
Results 1 - 10 of 95. Search took: 0.017 seconds
|Sort by: date | relevance|
[en] The aim of our research is to prepare high sulfur composite materials with the highest capacity, efficiency and cyclability. Subsequently, the best materials are also tested in real small prototypes of Li-S batteries. In particular, these cells should be much safer, more stable and cheaper than today's batteries. (authors)
[en] Wind energy is an important field of development for the island of Gotland, Sweden, especially since the island has set targets to generate 100% of its energy from renewable sources by 2025. Due to the variability of wind conditions, energy storage will be an important technology to facilitate the continued development of wind energy on Gotland and ensure a stable and secure supply of electricity. In this study, the feasibility of utilizing the Middle Cambrian Faludden sandstone reservoir on Gotland for Compressed Air Energy Storage (CAES) is assessed. Firstly, a characterization of the sandstone beneath Gotland is presented, which includes detailed maps of reservoir thickness and top reservoir structure. Analysis of this information shows that the properties of the Faludden sandstone and associated cap rock appear favorable for the application of CAES. Seven structural closures are identified below the eastern and southern parts of Gotland, which could potentially be utilized for CAES. Scoping estimates of the energy storage capacity and flow rate for these closures within the Faludden sandstone show that industrial scale CAES could be possible on Gotland.
[en] Lithium-ion batteries (LIBs) have been widely used in many fields such as portable electronics and electric vehicles since their successful commercialization in the 1990s. However, the electrochemical performance of current commercial LIBs still needs to be further improved to meet the continuously increasing demands for energy storage applications. Recently, tremendous research efforts have been made in developing next-generation LIBs with enhanced electrochemical performance. In this review, we mainly focus on the recent progress of LIBs with high electrochemical performance from four aspects, including cathode materials, anode materials, electrolyte, and separators. We discuss not only the commercial electrode materials (LiCoO2, LiFePO4, LiMn2O4, LiNixMnyCozO2, LiNixCoyAlzO2, and graphite) but also other promising next-generation materials such as Li-, Mn-rich layered oxides, organic cathode materials, Si, and Li metal. For each type of materials, we highlight their problems and corresponding strategies to enhance their electrochemical performance. Nowadays, one of the key challenges to construct high-performance LIBs is how to develop cathode materials with high capacity and working voltage. This review provides an overview and future perspectives to develop next-generation LIBs with high electrochemical performance.
[en] A well-designed redox-active organic linker, pyrazine-2,3,5,6-tetracarboxylate (H4pztc) with brimming active sites for lithium ions storage was utilized to construct coordination polymers (CPs) via a facile hydrothermal reaction. Those two isostructural two-dimensional (2D) CPs, namely [M2(pztc)(H2O)6]n (M=Co for 1 and Ni for 2), delivered excellent reversible capacities and stable cycling performance as anodes in lithium ion batteries. As demonstrated in electrochemical studies, 1 and 2 can achieve highly reversible capacities of 815 and 536 mA h g−1 at 200 mA g−1 for 150 cycles, respectively, best performed for the reported 2D-CP-based anode materials. The electrochemical mechanism studies showed that the remarkable performances can be ascribed to the synergistic Li-storage redox reactions of metal centers and organic moieties. Our work highlights the opportunities of using a well-designed organic ligand to construct low-dimensional CPs as new type of electrode materials for advanced lithium ion batteries.
[en] Ba(OH)2 · 8H2O is one important Phase Change Material (PCM), but its usage is restricted by its large supercooling degree. In this work, several nucleating agents were tested to improve its thermal storage performance: BaSO4, BaCl2 · 2H2O, Na2B4O7 · 10H2O and Na2HPO4 · 12H2O. The test was done by a melt-solidification heating cycle experiment. The results show that all these nucleating agents can inhibit the supercooling characteristics of Ba(OH)2 · 8H2O. More important, the Differential Scanning Calorime (DSC) test indicates that BaCl2 · 2H2O can be used as one suitable nucleating agent since the Ba(OH)2 · 8H2O/BaCl2 · 2H2O composite can keep higher latent heat. With BaCl2 · 2H2O as the nucleating agent and sodium carboxymethylcellulose (CMC) as thickener, the Ba(OH)2 · 8H2O composite possesses a smaller supercooling degree and can maintain a favourable thermal storage performance. (paper)
[en] We introduce an explicit theoretical formula for the heat capacity peaks that occur in materials during phase changes. Such materials are of importance in many applications where thermal energy storage is needed, including solar systems, buildings, electronic devices, or radionuclide encasements. We show how theoretical parameters that appear in the formula can be adjusted in order to fit experimentally measured peaks. Two of these parameters are interesting in applications: the specific latent heat and phase change temperature. We illustrate this procedure for four peaks associated with phase changes in four different materials for which the heat capacity peaks had been measured at slow heating rates.
[en] Lithium metal is used to achieve high-energy-density batteries due to its large theoretical capacity and low negative electrochemical potential. The introduction of quasi-solid electrolytes simultaneously overcomes the safety problems induced by the liquid electrolytes and the high interfacial resistance issues confronted by all solid-state electrolytes. In-depth investigations involving interfacial behaviors in quasi-solid lithium metal batteries are inadequate. Herein an ultrathin LiOCl quasi-solid-state electrolyte layer (500 nm thickness) is used to cover a lithium anode. The polarization of the anode is remarkably reduced by introducing the LiOCl quasi-solid-state electrolyte. In contrast to the decomposition of solvents in a standard electrolyte (EC-DEC,1.0 m LiPF), the established quasi-solid-state electrolyte interfaces can significantly inhibit the decomposition of solvents when the cut-off voltage is 4.5 V. (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)
[en] Herein, molecular layer deposition is used to form a nanoscale "zircone" protective layer on Li metal to achieve stable and long life Li metal anodes. The zircone-coated Li metal shows enhanced air stability, electrochemical performance and high rate capability in symmetrical cell testing. Moreover, as a proof of concept, the protected Li anode is used in a next-generation Li-O battery system and is shown to extend the lifetime by over 10-fold compared to the batteries with untreated Li metal. Furthermore, in-situ synchrotron X-ray absorption spectroscopy is used for the first time to study an artificial SEI on Li metal, revealing the electrochemical stability and lithiation of the zircone film. This work exemplifies significant progress towards the development and understanding of MLD thin films for high performance next-generation batteries. (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)