Explore the vast range of titles available.

In this work, two thin hybrid composites based on organic-like fullerenes (bucky balls C 60 ) and inorganic compounds of lithium cobalt oxide (LiCoO 2 ) were prepared. The composites were synthesized by a combined method of ion sputtering and evaporation. The prepared samples were sandwiched between 2 gold electrodes and subjected to charging at an applied small voltage. After each charging process, the samples were analyzed using two appropriate methods—the surface morphology was monitored using AFM (Atomic Force Microscopy), and lithium depth concentration profiles were measured using NDP (Neutron Depth Profiling). The results of the measurements showed that both types of composite experienced significant changes both in the surface morphology and especially in the depth distribution of lithium. The test confirmed the expectation that the unusual hybrid combination of organic and inorganic phases is electrochemically active and exhibits characteristics of Li battery behavior.

Solid electrolytes (SEs) are widely considered as an ‘enabler’ of lithium anodes for high-energy batteries. However, recent reports demonstrate that the Li dendrite formation in Li 7 La 3 Zr 2 O 12 (LLZO) and Li 2 S–P 2 S 5 is actually much easier than that in liquid electrolytes of lithium batteries, by mechanisms that remain elusive. Here we illustrate the origin of the dendrite formation by monitoring the dynamic evolution of Li concentration profiles in three popular but representative SEs (LiPON, LLZO and amorphous Li 3 PS 4 ) during lithium plating using time-resolved operando neutron depth profiling. Although no apparent changes in the lithium concentration in LiPON can be observed, we visualize the direct deposition of Li inside the bulk LLZO and Li 3 PS 4 . Our findings suggest the high electronic conductivity of LLZO and Li 3 PS 4 is mostly responsible for dendrite formation in these SEs. Lowering the electronic conductivity, rather than further increasing the ionic conductivity of SEs, is therefore critical for the success of all-solid-state Li batteries. Despite its importance in lithium batteries, the mechanism of Li dendrite growth is not well understood. Here the authors study three representative solid electrolytes with neutron depth profiling and identify high electronic conductivity as the root cause for the dendrite issue.

Electrical mobility demands an increase of battery energy density beyond current lithium-ion technology. A crucial bottleneck is the development of safe and reversible lithium-metal anodes, which is challenged by short circuits caused by lithium-metal dendrites and a short cycle life owing to the reactivity with electrolytes. The evolution of the lithium-metal-film morphology is relatively poorly understood because it is difficult to monitor lithium, in particular during battery operation. Here we employ operando neutron depth profiling as a noninvasive and versatile technique, complementary to microscopic techniques, providing the spatial distribution/density of lithium during plating and stripping. The evolution of the lithium-metal-density-profile is shown to depend on the current density, electrolyte composition and cycling history, and allows monitoring the amount and distribution of inactive lithium over cycling. A small amount of reversible lithium uptake in the copper current collector during plating and stripping is revealed, providing insights towards improved lithium-metal anodes. Rechargeable lithium metal batteries could offer a major leap in energy capacity but suffer from the electrolyte reactivity and dendrite growth. Here the authors apply neutron depth profiling to provide quantitative insight into the evolution of the Li-metal morphology during plating and stripping.

[See PDF for image] Fig. 2 Opening The Young Scientists’ Award of the International Committee of Activation Analysis this year was presented to Iaroslav Meleshenkovskii from the Jülich Center for Neutron Sciences, whose paper is also included here. Instrumental neutron activation analysis Facilities k0-based neutron activation analysis Comparison to other methods Prompt gamma activation analysis Applications Activation analysis using fast neutrons and other particles Reference materials Neutron depth profiling 46 oral presentations together with eleven plenary talks were presented, while 45 posters were on display in the two afternoon poster sessions (Fig. 3). [See PDF for image] Fig. 3 Presentation of the Hevesy Medal Award, Balázs Réffy Director General of Akadémiai Kiadó, Amares Chatt Canada, also Chair of JRNC Board of the Hevesy Award, Elisabete A. De Nadai Fernandes the awardee, Zsolt Révay Editor-in-Chief of Journal of Radioanalytical and Nuclear Chemistry, the organizer of the conference The social programs included guided walks in the castle district and a dinner at the Feneketlen (Bottomless) lake.

Neutron depth profiling (NDP) is a non-destructive technique used for identifying the concentration of impurity isotopes below the sample surface. NDP is carried out by detection of the emitted charged particles resulting from bombarding the sample with neutrons. NDP specifies the isotopic concentration versus the sample depth for a few micrometers below the surface. The sample is bombarded inside a research reactor using a thermal neutron beam. Charged particles like alpha particles or protons are produced from the neutron induced reactions in the sample. Each neutron isotopic interaction produces a certain Q, indicating a specific kinetic energy for the emitted charged particle. As the charged particle travels through the sample to eject the surface, it loses energy to atoms (electrons) on its path. The charged particle energy loss holds information regarding the number of atoms by which the emitted particle passed, thus indicating its original depth. The purpose of this work is to check the capability of Artificial Neural Networks (ANNs) in predicting the boron concentration profile across a boro-silicate sample of thickness 3.5 μm divided into 10 layers. Each layer included different boron concentration than the other. Also, the boron concentration had the values {0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1}. Training, validation, and test data were generated synthetically using MCNP6 in which the boron concentrations varied in the layer number from one sample to another. MCNP6 model consisted of a silicon barrier detector, boro-silicate sample, chamber body and an idealized thermal neutron source. The detector, sample, and the source were located in a voided chamber. The samples were irradiated with a 0.025 eV monoenergetic thermal neutron beam from a monodirectional disk source. To cover the whole area of the samples, the thermal neutron beam had a radius of 3 cm. The silicon detector active volume was modelled as a 100 μm thick and 3 cm radius facing the sample directly. The sample, beam, and the detector were placed on the same axis. Ten ANN regression models were developed, one for each layer boron concentration prediction where the input for each model was the alpha spectrum read by the detector, while the output was the boron concentration for each layer. Results showed regression values higher than 0.94 for all of the developed models. ANNs proved its capability of predicting the boron profile form the alpha spectrum read by the detector regarding neutron depth profiling in a boro-silicate samples.

The nuclear analytical instruments at MLZ are based on the radiative neutron capture, i.e. they are activation analytical methods. Prompt gamma activation analysis and in-beam neutron activation analysis, installed at a high-flux cold neutron beam, have successfully been used for about ten years for the investigation of a large variety of samples. The same beam accommodates neutron depth profiling mainly serves lithium-ion battery studies. Neutron activation analysis uses the well-thermalized high-flux irradiation channels and it is major field of application is trace-element analyses, complementing the bulk analysis with PGAA.

Aluminum, due to its high abundance, very attractive theoretical capacity, low cost, low (de−) lithiation potential, light weight, and effective suppression of dendrite growth, is considered as a promising anode candidate for lithium‐ion batteries (LIBs). However, its practical application is hindered due to multiple detrimental challenges, including the formation of an amorphous surface oxide layer, pulverization, and insufficient lithium diffusion kinetics in the α‐phase. These outstanding intrinsic challenges need to be addressed to facilitate the commercial production of Al‐based batteries. The native passivation layer, Al2O3, plays a critical role in the nucleation and reversibility of lithiating aluminum and is thoroughly investigated in this study using high precision electrochemical micro calorimetry. The enthalpy of crystallization of β‐LiAl is found to be 40.5 kJ mol−1, which is in a strong agreement with the value obtained by calculation using Nernst equation (40.04 kJ mol−1). Surface treatment of the active material by the addition of 25 nm of alumina increases the nucleation energy barrier by 83 % over the native oxide layer. After the initial nucleation, the added alumina does not negatively impact the reversibility at 0.1 C rate, suggesting the removal of alumina is not necessary for improving the cyclability of aluminum anode based lithium‐ion batteries. Moreover, the coulombic efficiencies are also found to be slightly higher in the alumina treated samples compared to the untreated ones. Lithium accumulates close to the surface of the aluminium foil before decreasing towards the bulk. The influence of an additional Al2O3 coating layer on the lithiation of aluminium is studied with micro‐calorimetry. The enthalpy of crystallization of β‐LiAl is found to be 40.5 kJ mol−1. A thicker oxide layer leads to higher nucleation barriers for the β‐LiAl phase.

A protective covering is often required for neutron depth profiling (NDP) measurements of sensitive materials (e.g., Li-ion batteries). Addition of this layer can increase NDP profile energy broadening and depth assignment uncertainty. This study evaluates the magnitude of these effects when polyimide films of variable thicknesses are placed over Li-rich solids. Key results include a modeled increase in cold neutron beam attenuation with increased film thickness, a methodology for estimating profile energy broadening using a sigmoidal function, and, when using a thick layer, that the broadening will add uncertainity to the zero-depth position and depth scale assignment.

The accumulation of solid electrolyte interphases (SEI) in graphite anodes related to elevated formation rates (0.1C, 1C and 2C), cycling rates (1C and 2C), and electrode-separator lamination is investigated. As shown previously, the lamination technique is beneficial for the capacity aging in graphite-LiNi1/3Mn1/3Co1/3O2 cells. Here, surface resistance growth phenomena are quantified using electrochemical impedance spectroscopy (EIS). The graphite anodes were extracted from the graphite NMC cells in their fully discharged state and irreversible accumulations of lithium in the SEI are revealed using neutron depth profiling (NDP). In this post-mortem study, NDP reveals uniform lithium accumulations as a function of depth with lithium situated at the surface of the graphite particles thus forming the SEI. The SEI was found to grow logarithmically with cycle number starting with the main formation in the initial cycles. Furthermore, the EIS measurements indicate that benefits from lamination arise from surface resistance growth phenomena aside from SEI growth in superior anode fractions.

Boron (B) alloying transforms the magnetoelectric antiferromagnet Cr2O3 into a multifunctional single‐phase material which enables electric field driven π/2 rotation of the Néel vector. Nonvolatile, voltage‐controlled Néel vector rotation is a much‐desired material property in the context of antiferromagnetic spintronics enabling ultralow power, ultrafast, nonvolatile memory, and logic device applications. Néel vector rotation is detected with the help of heavy metal (Pt) Hall‐bars in proximity of pulsed laser deposited B:Cr2O3 films. To facilitate operation of B:Cr2O3‐based devices in CMOS (compementary metal‐oxide semiconductor) environments, the Néel temperature, TN, of the functional film must be tunable to values significantly above room temperature. Cold neutron depth profiling and X‐ray photoemission spectroscopy depth profiling reveal thermally activated B‐accumulation at the B:Cr2O3/ vacuum interface in thin films deposited on Al2O3 substrates. The B‐enrichment is attributed to surface segregation. Magnetotransport data confirm B‐accumulation at the interface within a layer of ≈50 nm thick where the device properties reside. Here TN enhances from 334 K prior to annealing, to 477 K after annealing for several hours. Scaling analysis determines TN as a function of the annealing temperature. Stability of post‐annealing device properties is evident from reproducible Néel vector rotation at 370 K performed over the course of weeks. Boron (B) alloying transforms the magnetoelectric antiferromagnet Cr2O3 into a multifunctional material allowing for voltage‐controllable Néel vector rotation. Cold neutron and X‐ray photoemission depth profiling together with magnetotransport measurements reveal B‐accumulation at interfaces with the functional B:Cr2O3 films. The B‐enrichment is attributed to surface segregation and accompanied by significant TN enhancement making B:Cr2O3 a candidate material for voltage‐controlled antiferromagnetic spintronics.