Cu-catalyzed Si-NWS grown on “carbon paper” as anodes for Li-ion cells

The very high theoretical capacity of the silicon (4200mAh/g more than 10 times larger than graphite), environmental-friendly, abundant and low-cost, makes it a potential candidate to replace graphite in high energy density Li-ion batteries. As a drawback, silicon suffers from huge volume changes (300%) on alloying and dealloying with Li, leading a structural deformation that induces disruption. The use of nanostructured silicon materials has been shown to be an effective way to avoid this mechanical degradation of the active material. In this paper the synthesis of silicon nanowires, grown on a highly porous 3D-like carbon paper substrate by CVD using Cu as the catalyst, is presented. The use of carbon paper allows to achieve remarkable loadings of active material (2-5 mg/cm2) and, consequently, high capacity densities. The silicon electrode was investigated both morphologically and electrochemically. To improve the electrochemical performance various strategies have been carried out. It was observed that a very slow first cycle (C/40), which helps the formation of a stable solid electrolyte interphase on the silicon surface, improves the performance of the cells; nevertheless, their cycle life has been found not fully satisfactory. Morphological analysis of the Si-NWs electrodes before and after cycling showed the presence of a dense silicon layer below the nanowires which could reduce the electrical contact between the active material and the substrate

Stability in a long length NbTi CICC

A crucial issue for a superconducting coil in order to be safely used in the magnetic system of a fusion reactor is stability against all foreseen disturbances. To simulate the fusion machine conditions, including off-normal events, e.g. plasma disruptions, the energy deposition has to be spread over a "long length" cable in conduit conductor (CICC) and a background magnetic field is needed. We have therefore designed and built an experiment consisting of an instrumented NbTi test module inserted in a pair of co-axial pulsed copper coils. A 0.6 m diameter superconducting coil provides a background magnetic field up to 3 T. Calibration of the energy inductively coupled between the pulsed coils and the module has been obtained measuring the system temperature increase just after the pulse by means of thermometers positioned along the conductor. Stability vs. operating current I/sub op/ has been examined for different helium temperatures and different background magnetic fields. The finite element code Gandalf for the stability and quenching transients analysis in forced flow cooled superconducting coils has been run to check the matching with the experimental results. (3 refs)

Reliability of Domestic Gas Flow Sensors with Hydrogen Admixtures

Static flow sensors (e.g., thermal gas micro electro-mechanical sensors—MEMS—and ultrasonic time of flight) are becoming the prevailing technology for domestic gas metering and billing since they show advantages in respect to the traditional volumetric ones. However, they are expected to be influenced in-service by changes in gas composition, which in the future could be more frequent due to the spread of hydrogen admixtures in gas networks. In this paper, the authors present the results of an experimental campaign aimed at analyzing the in-service reliability of both static and volumetric gas meters with different hydrogen admixtures. The results show that the accuracy of volumetric and ultrasonic meters is always within the admitted limits for subsequent verification and even within those narrower of the initial verification. On the other hand, the accuracy of the first generation of thermal mass gas flow sensors is within the limits of the verification only when the hydrogen admixture is below 2%vol. At higher hydrogen content, in fact, the absolute weighted mean error ranges between 3.5% (with 5%vol of hydrogen) and 15.8% (with 10%vol of hydrogen)

The ENEA′s 2019–2021 Three-Year Research Project on Electrochemical Energy Storage

This work describes the research activities carried out by ENEA in the three-year period 2019–2021 as a part of the Electrochemical Storage project. The project was part of a larger and more integrated project for energy storage, itself contained in the Electric System Research program. Within the project, various research lines were carried out: From the development of materials for electrodes to the testing of electrolytes and separators, both for lithium and sodium-ion batteries, evaluation of the use of lithium metal batteries, and studying how to give a second life to used batteries. Dissemination of the results was an integral part of the program. The reasons that have been adduced to articulate the research plan and the main results obtained are reviewed in this concept

DC and transient current distribution analysis from self-field measurements on ITER PFIS conductor

Current reconstruction in cable-in-conduit conductors (CICC) cables is a crucial issue to determine cables performance in working conditions, and must be performed using inverse problem approaches as direct measurement is not feasible. The current distribution has been studied for the ITER Poloidal Field Insert Sample (PFIS) conductor using annular arrays of Hall probes placed in three different locations along the sample during the test campaign at the SULTAN facility. The measurement apparatus is also described in the paper, together with the approach to current reconstruction

Ricerca su materiali e processi per la realizzazione di materiali catodici con prestazioni migliorate. Analisi morfologica dei prodotti finali

I sali d’ammonio preparati con differenti metodologie sono stati trattati termicamente in presenza di litio per trasformarli in LiFePO4. Il trattamento termico è stato effettuato normalmente a 600°C per 2 ore mentre in due casi lo stesso è stato effettuato a differenti temperature (550 e 700°C). Le morfologie dei materiali così ottenuti sono state valutate sia in funzione della preparazione del precursore sia, per lo stesso precursore, in funzione del trattamento termico

Hydrogen blending effect on fiscal and metrological instrumentation: A review

A green hydrogen (H2) economy requires a sustainable, efficient, safe, and widespread infrastructure for transporting and distributing H2 from production to consumption sites. Transporting a hydrogen/natural gas (H2NG) mixture, including pure H2, through the existing European natural gas (NG) infrastructure is considered a cost-effective solution, particularly in the transitional phase. Several reasons justify the H2NG blending option. The NG infrastructure can be efficiently repurposed to transport H2, by blending H2 with NG, to operate as H2 daily storage, matching production and demand and to enable large-scale seasonal H2 storage. Although many benefits exist, the potential of existing NG grids for transporting and distributing green H2 may face limitations due to technical, economic, or normative concerns. This paper focuses on the state of the art of the European NG transmission and distribution metrology normative framework and identifies the gaps to be filled in case of H2NG flowing into the existing grids. The paper was revised to provide a comprehensive analysis of the practical implications resulting from the H2NG blend option

Hydrogen in natural gas grids: prospects and recommendations about gas flow meters

To inject green hydrogen (H2) into the existing natural gas (NG) infrastructure is one way to decarbonize the European energy system. However, asset readiness is necessary to be successful. Preliminary analysis and experimental results about the compatibility of hydrogen and natural gas mixtures (H2NG) with the actual gas grids make the scientific community confident about the feasibility. Nevertheless, specific technical questions need more research. A significant topic of debate is the impact of H2NG mixtures on the performance of state-of-the-art fiscal measuring devices, which are essential for accurate billing. Identifying and addressing any potential degradation in their metrological performance due to H2NG is critical for decision-making. However, the literature lacks data about the gas meters’ technologies currently installed in the NG grids, such as a comprehensive overview of their readiness at different concentrations while data are fragmented among different sources. This paper addresses these gaps by analyzing the main characteristics and categorizing more than 20,000 gas meters installed in THOTH2 project partners’ grids and by summarizing the performance of traditional technologies with H2NG mixtures and pure H2 based on literature review, operators experience and manufacturers knowledge. Based on these insights, recommendations are given to stakeholders on overcoming the identified barriers to facilitate a smooth transition