Evaluation of Hydrogenation Kinetics and Life Cycle Assessment on Mg2NiHx-CaO Composites.

Magnesium-based alloys are attractive as hydrogen storage materials due to their lightweight and high absorption, but their high operating temperatures and very slow kinetics are obstacles to practical applications. Therefore, the effect of CaO has improved the hydrogenation kinetics and slowed down the degradation. The Mg2NiHx-CaO composites were prepared by hydrogen-induced mechanical alloying (HIMA). Hydrogenation kinetics was performed by using an Automatic PCT Measuring System and evaluated in the temperature range of 423, 523, and 623 K. As a result of calculating the hydrogen absorption amounts through the hydrogenation kinetics curve, they were calculated as about 0.52 wt%, 1.21 wt%, and 1.59 wt% (Mg2NiHx-10 wt% CaO). In this study, the material environmental aspects of Mg2NiHx-CaO composites were investigated through life cycle assessment (LCA). LCA was performed analyzing the environmental impact characteristics of the manufacturing process by using Gabi software and the Eco-Indicator 99' and Centrum voor Milieuweten schappen (CML 2001) methodology. As a result, the contents of global warming potential (GWP) and fossil fuels were found to have a higher impact than other impact categories.

Novel Composition of Co-Free LiNi0.875-xMn0.125AlxO2 Cathode Materials.

Ni-rich LiNi1-xMnxO2 cathode materials have attracted widespread interest as promising alternative cathode materials owing to their higher capacity, lower cost, and lower toxicity compared to those of LiCoO2. Therefore, we designed herein a LiNi0.875Mn0.125O2 positive electrode material. However, as the Ni content increases, the materials suffer from an extensive phase transition during the de-lithiation process owing to the low-bond strength of Ni (391.6 kJ mol-1) and Mn (402 kJ mol-1). In this study, Al-doped LiNi0.875-xMn0.125AlxO2 (x= 0, 0.05, 0.1) was synthesized using the coprecipitation method. Al had a higher bond strength (512 kJ mol-1) between oxygen and metal ions compared to that of Ni and Mn ions. Additionally, Al is usually stabilized in the form of Al3+. Therefore, the increased bond strength decreased the electrostatic repulsion with oxygen during the de-lithiation process and prevented cation mixing by stabilizing the Ni ion's valence, thereby resulting in increased structural stability. X-ray diffraction (XRD) was used to characterize their structures and calculate the cation mixing value. The electrochemical properties showed that LiNi0.775Mn0.125Al0.1O2 exhibited the high capacity retention of 97.1% after 30 cycles at 1 C at 55 °C.

Effect of PEDOT:PSS (Poly(3,4-ethylenedioxythiophene)-polystyrenesulfonate) Coating on Nanostructured Cobalt-Free LiNi0.9Mn0.1O2 Layered Oxide Cathode Materials for Lithium-Ion Battery.

Among cobalt-free layered oxides, Li(Ni1-xMnx)O2 (x ≤0.5) (LNMO) shows high reversible capacity, good cycling performance and thermal stability, and has relatively low cost and toxicity due to the absence of cobalt. In this study, we synthesized LNMO cathode materials having a porous fiber shape with primary particles that had an average diameter of about 328 nm. The prepared LNMO has an increased surface area, on which side reactions between the electrolyte and cathode material occur. Therefore, we coated the conductive polymer PEDOT:PSS to solve the problems that may arise. The coated LNMO exhibited a reversible capacity of 128.03 mAh g-1, and 87.1% capacity retention, at a current density of 0.1 C, for up to 30 cycles. It showed a better performance than uncoated LNMO. The process used in this study can be proposed as a new synthesis method for cobalt-free layered oxide materials.

Hydrogenation Properties of Mg-Al-Zn-CaO-Hx Prepared by Hydrogen Induced Mechanical Alloying (HIMA).

Mg and Mg-system alloys are the materials of choice among hydrogen energy storage media due to their high hydrogen storage capacity (7.6 wt.%) and lighter weight (Huot, J., et al., 1999. Structural study and hydrogen sorption kinetics of ball-milled magnesium hydride. Journal of Alloys and Compounds, 293, pp.495-500). However, the formation of hydrogen products at high temperatures, the phenomenon of rapid alloy deterioration, and the low rate of reaction in the hydriding and dehydriding processes have been the main hindrances to commercialization of these alloys for hydrogen storage. In this study, to increase the reaction rate with hydrogen, Mg-Al-Zn-CaO-Hx hydrogen storage alloys were fabricated HIMA (Seok, S., et al., 2005. Evaluations of microstructure and hydrogenation properties on Mg2NiHx. Transactions of the Korean Hydrogen and New Energy Society, 16(3), pp.238-243). The Alloying times of 72 and 96 h and BCR of 30:1 and 66:1 were used for the HIMA process; the rotation speed was fixed at 200 rpm and the hydrogen pressure was 3 Mpa. SEM was used to confirm the shape of the particles. The crystal structure of the synthesized materials was analyzed by XRD, and BET measurements were performed to determine the correlation between the BCR and specific surface area. The weight change of the composite material was measured by TGA, and the kinetics was evaluated to determine the hydrogen adsorption rate (at 150, 250, and 350 °C).

Effect of MWCNT (Multi-Walled Carbon Nano-Tube) Doping on Hydrogenation Kinetics of Mg-CaO Alloys.

Magnesium hydride has a high hydrogen storage capacity (7.6 wt.%), and is cheap and lightweight, thus advantageous as a hydrogen storage alloy. However, Mg-based hydrides undergo hydrogenation/ dehydrogenation at high temperature and pressure due to their thermodynamic stability and high oxidation reactivity. Various attempts have been made to lower the reaction rate and dehydrogenation temperature by adding transition elements (e.g., Ti, Fe, Co, Ni, Ce), metal oxides, and intermetallic compounds to overcome these shortcomings. On the other hand, carbon materials have been mainly studied in the field of hydrogen storage with high specific surface area and lightweight properties; however, results show that they cannot store a large amount of hydrogen. Recently, it has been theoretically reported that carbon materials act as adsorbents in hydrogen storage. This study focuses on the hydrogenation behavior of MgHx-CaO and MgHx-CaO-MWCNT composites prepared by hydrogen-induced mechanical alloying, and investigates the properties of these composite materials.

Preparation and Effect of (3-aminopropyl)triethoxysilane-Coated LiNi0.5Co0.2Mn0.3O2 Cathode Material for Lithium Ion Batteries.

Surface coating using (3-aminopropyl)triethoxysilane (APTES) has been applied to improve the electrochemical properties of LiNi0.5Co0.2Mn0.3O2 (NCM523) cathode materials. The APTES coating layer on the surface of NCM523 protects the direct contact area between the cathode material and the electrolyte, and facilitates the presence of electrons through the abundance of electron-rich amine groups, thereby improving electrochemical performance. X-ray photoelectron spectroscopy confirmed the existence of APTES coating layers on the surface of NCM523 cathode materials, revealing three peaks-N1s, O1s, and Si1s-that were not identified in bare NCM523. In addition, the discharge capacities of the bare electrode and the APTES-coated NCM523 electrode were 121.06 mAh/g and 156.43 mAh/g, respectively. To the best of our knowledge, the use of an APTES coating on NCM523 cathode materials for lithium-ion batteries has never been reported.

The Evaluations of Hydrogen Permeation and Life Cycle Assessment on Nanocrystallined TiN-BCY Hydrogen Membrane.

Recently, Membrane technologies are used for the separation of mixtures in various industries. The promising method to reduce the CO2 emission and production of H2 from the coal based power plants is membrane separation with polymer, metal, ceramic and cermet materials. In this study, TiN ceramic material was selected, that is much less expensive than Pd. Also it has resistance to acids and chemically steady. Yttrium doped barium cerate (BCY) is a proton conductor. This perovskite exhibit both high proton conductivity and thermodynamic stability. But its chemical stability is very low under real operating environments. Thus, TiN-BCY may provide'a new membrane material for application. Life cycle assessment (LCA) based on fabrication of membrane and it was carried out to evaluate the energy demand and environmental impact. The analysis is performed according to the recommendations of ISO norms 14040 and obtained using the Gabi 6 software. This LCA will contribute to optimizing the eco-design, reducing the energy consumption and pollutant emissions during the eco-profiles of the TiN-BCY membrane.

Life Cycle Assessment for Proton Conducting Ceramics Synthesized by the Sol-Gel Process.

In this report, the environmental aspects of producing proton conducting ceramics are investigated by means of the environmental Life Cycle Assessment (LCA) method. The proton conducting ceramics BaZr0.8Y0.2O3-δ (BZY), BaCe0.9Y0.1O2.95 (BCY10), and Sr(Ce0.9Zr0.1)0.95Yb0.05O3-δ (SCZY) were prepared by the sol-gel process. Their material requirements and environmental emissions were inventoried, and their energy requirements were determined, based on actual production data. This latter point makes the present LCA especially worthy of attention as a preliminary indication of future environmental impact. The analysis was performed according to the recommendations of ISO norms 14040 and obtained using the Gabi 6 software. The performance of the analyzed samples was also compared with each other. The LCA results for these proton conducting ceramics production processes indicated that the marine aquatic ecotoxicity potential (MAETP) made up the largest part, followed by fresh-water aquatic ecotoxicity potential (FAETP) and Human Toxicity Potential (HTP). The largest contribution was from energy consumption during annealing and calcinations steps.