“…1) and leads to lithium carbonate as a final product, in agreement with the experimental findings [24,25].…”
Section: Anhydrous Lithium Oxalatesupporting
confidence: 80%
“…The prediction of the next step in this structure is difficult, since naïve analysis based on bond orders would suggest wrongly thermal decomposition to metal and carbon dioxide (similar to e.g., anhydrous cadmium or silver oxalate [14,15]). But it is well-known from the experiment [24,25] that anhydrous lithium oxalate decompose thermally to lithium carbonate and then-in much higher temperature-to lithium oxide. What is more, such process of formation of metallic lithium would necessitate quite big charge transfer from oxygen atoms in COO -anions to lithium cations, which taking into account their calculated net charge equal to ?0.85e and the difference in electronegativity between oxygen and lithium and strongly ionic character of Li-O bonds is not plausible and one can safely assume that much more probable is the process of breaking of these bonds, without charge transfer between lithium and oxygen and setting COO -anions free inside the gaps within cationic sub-lattice.…”
The theoretical analysis of electronic structure and bonding properties of anhydrous alkali metal oxalates, based on the results of DFT FP-LAPW calculations, Bader's QTAIM topological properties of electron density, Cioslowski and Mixon's topological bond orders [reported in the first part of this paper by Kole_ zyński (doi: 10.1007/s10973-013-3126-z)] and Brown's Bond Valence Model calculations, carried out in the light of thermal decomposition pathway characteristic for these compounds are presented. The obtained results shed some additional light on the origins of the complex pathway observed during thermal decomposition process (two stage process, first the formation of respective carbonate and then decomposition to metal oxide and carbon dioxide). For all structures analyzed, strong similarities in electronic structure and bonding properties were found (ionic-covalent bonds in oxalate anion with C-C bond as the weakest one in entire structure and almost purely ionic between oxalate group and alkali metal cations), allowing us to propose the most probable pathway consisting of consecutive steps, leading to carbonate anion formation with simultaneous cationic sublattice relaxations, which results in relative ease of respective metal carbonate formation.
“…1) and leads to lithium carbonate as a final product, in agreement with the experimental findings [24,25].…”
Section: Anhydrous Lithium Oxalatesupporting
confidence: 80%
“…The prediction of the next step in this structure is difficult, since naïve analysis based on bond orders would suggest wrongly thermal decomposition to metal and carbon dioxide (similar to e.g., anhydrous cadmium or silver oxalate [14,15]). But it is well-known from the experiment [24,25] that anhydrous lithium oxalate decompose thermally to lithium carbonate and then-in much higher temperature-to lithium oxide. What is more, such process of formation of metallic lithium would necessitate quite big charge transfer from oxygen atoms in COO -anions to lithium cations, which taking into account their calculated net charge equal to ?0.85e and the difference in electronegativity between oxygen and lithium and strongly ionic character of Li-O bonds is not plausible and one can safely assume that much more probable is the process of breaking of these bonds, without charge transfer between lithium and oxygen and setting COO -anions free inside the gaps within cationic sub-lattice.…”
The theoretical analysis of electronic structure and bonding properties of anhydrous alkali metal oxalates, based on the results of DFT FP-LAPW calculations, Bader's QTAIM topological properties of electron density, Cioslowski and Mixon's topological bond orders [reported in the first part of this paper by Kole_ zyński (doi: 10.1007/s10973-013-3126-z)] and Brown's Bond Valence Model calculations, carried out in the light of thermal decomposition pathway characteristic for these compounds are presented. The obtained results shed some additional light on the origins of the complex pathway observed during thermal decomposition process (two stage process, first the formation of respective carbonate and then decomposition to metal oxide and carbon dioxide). For all structures analyzed, strong similarities in electronic structure and bonding properties were found (ionic-covalent bonds in oxalate anion with C-C bond as the weakest one in entire structure and almost purely ionic between oxalate group and alkali metal cations), allowing us to propose the most probable pathway consisting of consecutive steps, leading to carbonate anion formation with simultaneous cationic sublattice relaxations, which results in relative ease of respective metal carbonate formation.
“…After 330 °C there is an intermediate stage until formation of LiMn 2 O 4 from association of MnO 2 , Mn 2 O 3 and Li 2 CO 3 at 450 °C as illustrated above in XRD of sample E450. The transformation from lithium oxalate to lithium carbonate was confirmed before [36] to occur in the range of 400–500 °C. After this temperature combination between these three phases takes place to start to form pure spinel LiMn 2 O 4 by the synergistic effect of the three components which still stable to more than 950 °C.Fig.…”
This study succeeded to prepare three pure phases of Mn
2
O
3
, Mn
3
O
4
beside one of the best cathode materials, spinel LiMn
2
O
4
. LiMn
2
O
4
with high phase purity and crystallinity was synthesized by a facile, cost effective and one step synthesis method. The structure and morphology of the powders were studied in detail by means of X-ray diffraction (XRD), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM) and surface area. The X-ray diffraction shows that the post-annealing process reveals the formation of pure crystalline spinel LiMn
2
O
4
with small particle size and lower lattice strain. The thermogravimetric analysis threw the light on the role of the evaporation technique in producing LiMn
2
O
4
by following the different phases on the thermal performance of the precursor. The morphological characterization shows the clear appearance of the octahedral particles of LiMn
2
O
4
calcined at high temperature with microporous nanosized structure. Electrochemical testing of the as prepared spinel at 900 °C showed promising results in terms of high initial capacity and good cycle stability. The as prepared spinel sample shows also good rate performance.
“…The thermal decomposition of lithium oxalate was also previously studied [42][43][44][45]. As is described in the literature, the formation of gas products is highly dependent on the atmosphere in which the TGA measurement is performed [43,44,49].…”
Section: Flame Retardants and Co 2 Releasementioning
confidence: 99%
“…Nevertheless, it is conceivable that the released CO 2 has a fire-retardant effect or can influence the gas composition limits for explosion. Lithium oxalate in particular has already been investigated mechanistically; therefore, it is known that it decomposes into the corresponding lithium carbonate at approximately 550 • C, with the CO being split off [42][43][44][45]. The CO immediately reacts again in the presence of oxygen, forming CO 2 .…”
Lithium-ion batteries are being increasingly used and deployed commercially. Cell-level improvements that address flammability characteristics and thermal runaway are currently being intensively tested and explored. In this study, three additives—namely, lithium oxalate, sodium fumarate and sodium malonate—which exhibit fire-retardant properties are investigated with respect to their incorporation into graphite anodes and their electro/chemical interactions within the anode and the cell material studied. It has been shown that flame-retardant concentrations of up to approximately 20 wt.% within the anode coating do not cause significant capacity degradation but can provide a flame-retardant effect due to their inherent, fire-retardant release of CO2 gas. The flame-retardant-containing layers exhibit good adhesion to the current collector. Their suitability in lithium-ion cells was tested in pouch cells and, when compared to pure graphite anodes, showed almost no deterioration regarding cell capacity when used in moderate (≤20 wt.%) concentrations.
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