Tracing structural changes in energy materials: A novel multi sample capillary setup for in house powder X‐ray diffraction

Lithium ion batteries (LIBs) are currently a major subject of applied electrochemical research as there is a fast growing demand of electrochemical energy storage, driven by the transformation of the automotive sector and the expansion of renewable energies. One of the key strategies to improve LIBs is the optimization of the cathode active materials (CAMs). Therefore, in order to find structure property relations, both crystallographic and electrochemical properties need to be investigated and well understood. However, standard laboratory powder X-ray diffraction (PXRD) possibly comes to its limit when minor structural variations such as atomic defects, cation order, or minor impurity phases are addressed. In order to focus on such minor structural changes and to find decisive differences in crystalline properties of battery materials, a multi-sample capillary setup for a multipurpose in-house PXRD setup was developed. The latter is made up from a six-circle diffractometer, a microfocus molybdenum rotating anode, and a 2D area detector. The capillary spinner itself is made from commercial components and simple custom-made adapters. A goniometer head is installed on a rotary module and sample spinning is enabled by a 12 V gear motor. Mounted on a xyz-stage of the diffractometer, the position of the rotating capillary exposed to the primary beam can be varied while remaining perfectly aligned in the center of the diffractometer. Hence, by packing up to 10 different powder samples separated from each other into a single glass capillary, subsequent measurements of all samples can be carried out without remounting or readjustment. Within a series of samples, the setup is extremely reliable, precise, and accurate, while errors originating from sample displacement, misalignment, or calibration are minimized

Impact of Particle and Crystallite Size of Ba0.6_{0.6}Sr0.4_{0.4}TiO3_3 on the Dielectric Properties of BST/P(VDF-TrFE) Composites in Fully Printed Varactors

In the field of printed electronics, electronic components such as varactors are of special interest. As ferroelectric materials, Ba$_{0.6}$Sr$_{0.4}$TiO$_3$ (BST) and poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) are promising compounds to be used in functional inks for the fabrication of fully inkjet-printed dielectric layers. In BST/P(VDF-TrFE) composite inks, the influence of the particle and crystallite size is investigated by using different grinding media sizes and thermal treatments at varying temperatures. It was found that with an increasing particle and crystallite size, both the relative permittivity and tunability increase as well. However, the thermal treatment which impacts both the particle and crystallite size has a greater effect on the dielectric properties. An additional approach is the reduction in the dielectric layer thickness, which has a significant effect on the maximal tunability. Here, with a thickness of 0.9 µm, a tunability of 29.6% could be achieved in an external electric field of 34 V µm$^{−1}$

Enhancing the Stability of LiNio.5_{o.5}0Mn1.5_{1.5}O4_{4} by Coating with LiNbO3_{3} Solid-State Electrolyte: Novel Chemically Activated Coating Process versus Sol-Gel Method

LiNbO$_{3}$-coated LiNi$_{0.5}$Mn$_{1.5}$O$_{4}$ spinel was fabricated by two methods: using hydrogen-peroxide as activating agent and sol-gel method. The structure of the obtained cathode materials was investigated using a scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and the electrochemical properties of the prepared cathodes were probed by charge-discharge studies. The morphology of the coating material on the surface and the degree of coverage of the coated particles were investigated by SEM, which showed that the surface of LiNi$_{0.5}$Mn$_{1.5}$O$_{4}$ particles is uniformly encapsulated by lithium innovate coating. The influence of the LiNbO3 coating layer on the spinel’s properties was explored, including its effect on the crystal structure and electrochemical performance. XRD studies of the obtained coated active materials revealed very small expansion or contraction of the unit cell. From the capacity retention tests a significant improvement of the electrochemical properties resulted when a novel chemically activated coating process was used. Poorer results, however, were obtained using the sol-gel method. The results also revealed that the coated materials by the new method exhibit enhanced reversibility and stability compared to the pristine and reference ones. It was shown that the morphology of the coating material and possible improvement of communication between the substrates play an important role

On the Composition of LiNi0.5_{0.5}Mn1.5_{1.5}O4_4 Cathode Active Materials

LiNi$_{0.5}$Mn$_{1.5}$O$_4$ (LNMO) cathode active materials for lithium-ion batteries have been investigated for over 20 years. Despite all this effort, it has not been possible to transfer their favorable properties into applicable, stable battery cells. To make further progress, the research perspective on these spinel type materials needs to be updated and a number of persisting misconceptions on LNMO have to be overcome. Therefore, the current knowledge on LNMO is summarized and controversial points are addressed by detailed considerations on the composition and crystallography of LNMO. The findings are supported by an in-situ high temperature X-ray diffraction study and the investigation of four different types of LNMO materials, including Mn(III) rich ordered LNMO, and disordered LNMO with low Mn(III) content. It is shown that the importance of cation order is limited to a small composition range. Furthermore, new evidence contradicting the idea of oxygen defects in LNMO is presented and an enhanced classification of LNMO based on the Ni content of the spinel phase is proposed. Moreover, a balanced chemical equation for the formation of LNMO is presented, allowing for comprehensive calculations of key properties of LNMO materials. Finally, suitable target compositions and calcination programs are suggested to obtain better LNMO materials

On the environmental competitiveness of sodium-ion batteries under a full life cycle perspective – a cell-chemistry specific modelling approach

Sodium-ion batteries (SIB) are among the most promising type of post-lithium batteries, being promoted for environmental friendliness and the avoidance of scarce or critical raw materials. However, the knowledge-base in this regard is weak, and comparatively little is known about the environmental performance of different SIB types in comparison with current lithium-ion batteries (LIB) under consideration of the whole battery life cycle (‘cradle-to-grave’). This work provides a complete and comprehensive update of the state of knowledge in the field of life cycle assessment of SIB. It develops and discloses a specific tool for dimensioning and assessing SIB cells, including a cell-specific model of an advanced hydrometallurgical recycling process. It provides the corresponding inventory data for five different types of SIB and compares their environmental impacts with those of competing LIB, taking into account the full life cycle (cradle-to-grave) and an individual cell dimensioning based on electrochemical considerations. Recycling is found to be highly relevant for minimizing environmental impacts of the batteries, though its benefit depends strongly on the individual cell chemistry. Deep recycling might not be favourable for cathodes based on abundant materials and could even increase impacts. Especially the assessed manganese and nickel–manganese based SIB chemistries show promising results, given that they achieve at least similar lifetimes as their LIB counterparts

Correction: On the environmental competitiveness of sodium-ion batteries under a full life cycle perspective – a cell-chemistry specific modelling approach

Correction for ‘On the environmental competitiveness of sodium-ion batteries under a full life cycle perspective – a cell-chemistry specific modelling approach’ by Jens F. Peters et al., Sustainable Energy Fuels, 2021, 5, 6414–6429, DOI: 10.1039/D1SE01292D

Instantaneous Surface Li3_{3}PO4_{4} Coating and Al–Ti Doping and Their Effect on the Performance of LiNi0.5_{0.5}Mn1.5_{1.5}O4_{4} Cathode Materials

Using hydrogen peroxide (H2O2), a novel approach was applied for the synthesis of LiNi0.5Mn1.5O4 (LNMO) coated with Li3PO4 and doped with Al3+ and Ti4+ ions. The reaction between LNMO and H2O2 resulted in particles with a partially damaged surface. If the same reaction is done in the presence of lithium, aluminum, titanium, and phosphate ingredients, then all particle facets are intact and show no sign of destruction. It appears that the H2O2 decomposition activates the LNMO surface, generating perfect conditions for the homogeneous deposition of the Li, Al, Ti, and phosphate ions. Electrochemical investigations show a very slow fading process during the cycling, and even after more than 500 cycles, the obtained cathode material shows a high specific capacity of 127 mAh g–1 (at 1 C) (∼98% capacity retention) and an excellent Coulombic efficiency (99.5%)

Effect of Nanostructured and Open-Porous Particle Morphology on Electrode Processing and Electrochemical Performance of Li-Ion Batteries

A nanostructured, porous NCM cathode material is investigated regarding its behavior during electrode processing and electrochemical performance. The results are related to the densely packed NCM original material from which the nanostructure has been derived. Chemical composition and structural parameters are not affected by the nanostructuring process; changes are limited to the particle morphology in terms of primary particle size, specific surface area, and porosity. Electrodes containing a porous NCM material deliver lower adhesion strength values when adding identical amounts of PVDF binder. Increasing the binder fraction from four to six parts increases also the adhesion strength to an acceptable level without deteriorating the cell capacity. Despite initially high electrode porosities of 65–70%, electrodes with nanostructured NCM are capable of withstanding calendering to 40% porosity without destroying the porous particles. Full-cell tests with 50 mAh pouch cells and graphite anodes reveal substantially improved C-rate capabilities for the nanostructured material in relation to the commercial original NCM. The advantage increases with increasing C-rate and corresponds to shorter diffusion pathways in nanostructured NCM. Remarkably, even at low C-rates (C/20) where diffusion effects are considered secondary, porous NCM lies ahead of the original material. This can be explained by the higher surface area and thereby enlarged interface to the electrolyte, which eases delithiation. Long-term cycling up to 1100 cycles displayed further benefits for the nanostructured active material as one of the most prominent degradation factors, that is, crack formation and particle fragmentation, does not occur throughout the complete cycling procedure—in contrast to the bulk particles of original NCM