Layered P2-Nax_xMn3/4_{3/4}Ni1/4_{1/4}O2_2 Cathode Materials For Sodium-Ion Batteries: Synthesis, Electrochemistry and Influence of Ambient Storage

Sodium-ion batteries promise efficient, affordable and sustainable electrical energy storage that avoids critical raw materials such as lithium, cobalt and copper. In this work, a manganese-based, cobalt-free, layered Na$_x$Mn$_{3/4}$Ni$_{1/4}$O$_2$ cathode active material for sodium-ion batteries is developed. A synthesis phase diagram was developed by varying the sodium content x and the calcination temperature. The calcination process towards a phase pure P2-Na$_{2/3}$Mn$_{3/4}$Ni$_{1/4}$O$_2$ material was investigated in detail using in-situ XRD and TGA-DSC-MS. The resulting material was characterized with ICP-OES, XRD and SEM. A stacking fault model to account for anisotropic broadening of (10l) reflexes in XRD is presented and discussed with respect to the synthesis process. In electrochemical half-cells, P2-Na$_{2/3}$Mn$_{3/4}$Ni$_{1/4}$O$_2$ delivers an attractive initial specific discharge capacity beyond 200 mAh g−1, when cycled between 4.3 and 1.5 V. The structural transformation during cycling was studied using operando XRD to gain deeper insights into the reaction mechanism. The influence of storage under humid conditions on the crystal structure, particle surface and electrochemistry was investigated using model experiments. Due to the broad scope of this work, raw material questions, fundamental investigations and industrially relevant production processes are addressed

Selective CO methanation on isostructural Ru nanocatalysts: The role of support effects

Current demand for understanding the behavior of groups of related genes, combined with the greater availability of data, has led to an increased focus on statistical methods in gene set analysis. In this paper, we aim to perform a critical appraisal of the methodology based on graphical models developed in Massa et al. (2010) that uses pathway signaling networks as a starting point to develop statistically sound procedures for gene set analysis. We pay attention to the potential of the methodology with respect to the organizational aspects of dealing with such complex but highly informative starting structures, that is pathways. We focus on three themes: the translation of a biological pathway into a graph suitable for modeling, the role of shrinkage when more genes than samples are obtained, the evaluation of respondence of the statistical models to the biological expectations. To study the impact of shrinkage, two simulation studies will be run. To evaluate the biological expectation we will use data from a network with known behavior that offer the possibility of carrying out a realistic check of respondence of the model to changes in the experimental conditions

Effect of Presodiation Additive on Structural and Interfacial Stability of Hard Carbon | P2‐Na0.66Mn0.75Ni0.2Mg0.05O2 Full Cell

The compatibility between a corncob-derived hard carbon anode and a layered oxide cathode (Na0.66Mn0.75Ni0.2Mg0.05O2), as well as the effect of presodiation via cathode additive (Na2C4O4), are investigated in a sodium-ion full cell. Extensive physicochemical and electrochemical characterizations are performed to deeply investigate the structural and interfacial evolution of the materials in the presodiated cell, either within the single cycle or upon long-term cycling. The use of sacrificial cathode additives is generally regarded as a method to improve full cell performance, especially when using sodium-deficient materials. However, undesired effects upon decomposition of the sacrificial salt may arise due to the complexity of the system. In this study, it is evidenced that the presodiation changes the properties of the electrodes causing a worsening of the electrochemical performance of the cell during long-term cycling. The surface morphology of the cathode is negatively affected by the formation of holes/cracks, while redox processes associated with structural transformations are suppressed in the voltage window of interest, with partial structural deformations occurring during activation cycles. The SEI and CEI are also affected by the formation of insulating organic species, which lead to an increased thickness and interphase resistance hampering the charge transfer kinetics of the cell

MgO coated P2-Na0.67Mn0.75Ni0.25O2 layered oxide cathode for Na-Ion batteries

<p>This is the experimental raw data set associated with the following publication:<strong>MgO coated P2-Na<sub>0.67</sub>Mn<sub>0.75</sub>Ni<sub>0.25</sub>O<sub>2</sub> layered oxide cathode for Na-Ion batteries; </strong><em>Cornelius Gauckler, Gints Kucinskis, Lukas Fridolin Pfeiffer, Abdelaziz A. Abdellatif, Yushu Tang, Christian Kübel, Fabio Maroni, Ruihao Gong, Margret Wohlfahrt-Mehrens, Peter Axmann, Mario Marinaro.</em></p> <p>The data set is organised along the figures of the publication.</p&gt

MgO coated P2-Na0.67Mn0.75Ni0.25O2 layered oxide cathode for Na-Ion batteries

In this study, we propose an effective strategy to improve the electrochemical performance of a P2-Na0.67Mn0.75Ni0.25O2 (P2-MNO) cathode material for Na-ion batteries based on MgO surface coating. The MgO coating, with a thickness of ∼20–50 nm, is obtained by means of a facile wet-chemistry approach followed by heat treatment carried out at comparatively low temperatures (400–500 °C) in order to avoid possible Mg doping in the bulk of the P2-MNO. Detailed electrochemical investigations demonstrate improved electrochemical performance of the MgO-coated material (M-P2-MNO) in comparison to pristine bare one at both room and elevated (40 °C) temperatures. Operando differential electrochemical mass spectroscopy (DEMS) demonstrate that the MgO coating is effective in suppressing unwanted gas evolution due to side reactions thus stabilizing the cathode/electrolyte interface