“Dynamics of porous and amorphous magnesium borohydride to understand solid state Mg-ion conductors”
A comprehensive study combining x-ray total scattering and quasi elastic neutron scattering (QENS) to help unravelling the complex interplay of the structure-property-relationship in crystalline and amorphous Mg-ion conductor Mg(BH4)2. In this study, published in June 2020 in scientific reports – nature research, electrochemical impedance spectroscopy of crystalline and amorphous Mg(BH4)2 confirmed that the conductivity of the latter is ~2 orders of magnitude higher at 353 K. The challenge in understanding the root cause of the observed high conductivity, is the difficulty to determine the structure of amorphous glasses in general. Since glasses are x-ray amorphous, synchrotron total scattering was performed to calculate the corresponding pair distribution functions (PDF). PDF analyses indicate a higher amount of disorder regarding the [BH4]- tetrahedra as well as the preservation of a now highly disordered 3D net of interpenetrating channels. Additionally, QENS was employed to study the rotational mobility of the [BH4] units, proofing a much larger fraction of activated [BH4] rotations in amorphous Mg(BH4)2.To the text
“Thermally Induced Structural Reordering in Li- and Mn-Rich Layered Oxide Li Ion Cathode Materials”
In this article published in Chemistry of Materials the authors describe a gradual transformation from a trigonal layered structure toward a cubic spinel structure during electrochemical cycling results in an unwanted decay of the mean charge and discharge voltages, called “voltage fade”. A structural reordering was induced by a mild thermal treatment in lithiated as well as in delithiated electrodes, which results either in a partial recovery of the initial well-ordered state or in an intensification of the structural degradation toward a spinel-type cation ordering, respectively.
“Structural insights into the formation and voltage degradation of lithium- and manganese-rich layered oxides”Top 50 Chemistry and Materials Sciences Articles in Nature Communications: https://www.nature.com/collections/giacagiaca
Although high-energy lithium- and manganese-rich layered cathode materials can deliver 30 % excess capacity compared with today’s commercially used cathodes, the so-called voltage decay has been restricting their practical application. Here, we have investigated systematically the structural and compositional dependence of manganese-rich lithium insertion compounds on the lithium content provided during synthesis and the complexity in the synthesis pathways of layered Li[Li0.2Ni0.2Mn0.6]O2 oxide. The transformation of the lithium-rich layered phase to a lithium-poor spinel phase via an intermediate lithium-containing rock-salt phase with release of lithium/oxygen was discovered during ultra-long-term cycling.
Nat. Commun. 10, 5365 (2019)To the text
“Probing a battery electrolyte drop with ambient pressure photoelectron spectroscopy”
Operando ambient pressure photoelectron spectroscopy in realistic battery environments is a key development towards probing the functionality of the electrode/electrolyte interface in lithium-ion batteries that is not possible with conventional photoelectron spectroscopy. Here, we present the ambient pressure photoelectron spectroscopy characterization of a model electrolyte based on 1M bis(trifluoromethane)sulfonimide lithium salt in propylene carbonate. Our article provides insights into the liquid components of a lithium ion battery and the necessity to stabilize the liquid phases in ambient pressure photoelectron spectroscopy measurements.
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“NASICON-type air-stable and all-climate cathode for sodium-ion batteries with low cost and high-power density”
The development of low-cost and long-lasting all-climate cathode materials for sodium ion batteries is one of the key issues for the success of large-scale energy storage. Here, we synthesize a NASICON-type tuneable Na4Fe3(PO4)2(P2O7)/C nanocomposite which shows both excellent rate performance and outstanding cycling stability over more than 4400 cycles. Its air stability and all-climate properties are investigated, and its potential as the sodium host in full cells has been studied.
NASICON-Type Air-Stable and All-Climate Cathode for Sodium-Ion Batteries with Low Cost and High-Power DensityZu dem Artikel
In der gemeinsam von KIT und Universität Ulm getragenen Initiative „Energy Storage Beyond Lithium“ arbeiten Wissenschaftlerinnen und Wissenschaftler aus Elektrochemie, Materialwissenschaften, theoretischer Modellierung und Ingenieurwissenschaften in einem multidisziplinären Ansatz zusammen.Mehr...
In article published in Advanced Energy Materials No. 1803094, Weibo Hua, Björn Schwarz,Michael Knapp, Sylvio Indris and co-workers describe the transformation processes (from spinel to rock-salt to layered structure) observed during synthesis of Li-rich Co-free layered oxides that are used as cathode materials for Li-ion batteries, on a single particle. These processes are driven by incorporation of Li and O into the Li-free precursor.To the text