Analysis of Trace Impurities in Lithium Carbonate

Lithium carbonate (Li2CO3) is a critical raw material in cathode material production, a core of Li-ion battery manufacturing. The quality of this material significantly influences its market value, with impurities potentially affecting Li-ion battery performance and longevity. While the importance of impurity analysis is acknowledged by suppliers and manufacturers of battery materials, reports on elemental analysis of trace impurities in Li2CO3 salt are scarce. This study aims to establish and validate an analytical methodology for detecting and quantifying trace impurities in Li2CO3 salt. Various analytical techniques, including X-ray diffraction (XRD), scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM-EDX), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma optical emission spectroscopy (ICP-OES), were employed to analyze synthetic and processed lithium salt. X-ray diffraction patterns of Li2CO3 were collected via step-scanning mode in the 5–80° 2θ range. SEM-EDX was utilized for particle morphology and quantitative impurity analysis, with samples localized on copper tape. XPS equipped with a hemispherical electron analyzer was employed to analyze the surface composition of the salt. For ICP-OES analysis, a known amount of lithium salt was subjected to acid digestion and dilution with ultrapure water. Multielemental standard solutions were prepared, including elements such as Al, Cd, Cu, Fe, Mn, Ni, Pb, Si, Zn, Ca, K, Mg, Na, and S. Results confirmed the presence of the zabuyelite phase in XRD analysis, corresponding to the natural form of lithium carbonate. SEM-EDX mapping revealed impurities of Si and Al, with low relative quantification values of 0.12% and 0.14%, respectively. XPS identified eight potential impurity elements, including S, Cr, Fe, Cl, F, Zn, Mg, and Na, alongside Li, O, and C. Regarding ICP-OES analysis, performance parameters such as linearity, limit of detection (LOD), and quantification (LOQ), variance, and recovery were evaluated for analytical validation. ICP-OES results demonstrated high linearity (>0.99), with LOD and LOQ values ranging from 0.001 to 0.800 ppm and 0.003 to 1.1 ppm, respectively, for different elements. The recovery rate exceeded 90%. In conclusion, the precision of the new ICP-OES methodology renders it suitable for identifying and characterizing Li2CO3 impurities. It can effectively complement solid-state techniques such as XRD, SEM-EDX, and XPS

Summer (JJA) and winter (DJF) climatological seasonal net precipitation (E-P<0), from 1980 to 2000, estimated by integrating E-P over 10-day forward trajectories from the North Atlantic moisture source region, using the numerical approaches shown in <b>Figure 2</b>.

<p>Summer (JJA) and winter (DJF) climatological seasonal net precipitation (E-P<0), from 1980 to 2000, estimated by integrating E-P over 10-day forward trajectories from the North Atlantic moisture source region, using the numerical approaches shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0099046#pone-0099046-g002" target="_blank"><b>Figure 2</b></a>.</p

As for <b>Figure 3</b>, but for interannual variance of net precipitation (E-P<0).

<p>As for <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0099046#pone-0099046-g003" target="_blank"><b>Figure 3</b></a>, but for interannual variance of net precipitation (E-P<0).</p

Percentage magnitude of the differences in mean net precipitation with respect to the 21-year average (climatological scheme-mean) for each one of the approaches.

<p>Percentage magnitude of the differences in mean net precipitation with respect to the 21-year average (climatological scheme-mean) for each one of the approaches.</p

Pearson correlation of the 21-year of the net precipitation between the seasonal scheme-mean and the shorter time scale scheme-means (T test with 95% of significance).

<p>Pearson correlation of the 21-year of the net precipitation between the seasonal scheme-mean and the shorter time scale scheme-means (T test with 95% of significance).</p

Classical and Nonclassical Germanium Environments in High-Pressure BaGe₅

A new crystalline form of BaGe₅ was obtained at a pressure of 15(2) GPa in the temperature range from 1000(100) to 1200(120) K. Single-crystal electron and powder X-ray diffraction patterns indicate a body-centered orthorhombic structure (space group <i>Imma</i>, Pearson notation <i>oI</i>24) with unit cell parameters <i>a</i> = 8.3421(8) Å, <i>b</i> = 4.8728(5) Å, and <i>c</i> = 13.7202(9) Å. The crystal structure of <i>hp</i>-BaGe₅ consists of four-bonded Ge atoms forming complex layers with Ge–Ge contacts between 2.560(6) and 2.684(3) Å; the Ba atoms are coordinated by 15 Ge neighbors in the range from 3.341(6) to 3.739(4) Å. Analysis of the chemical bonding using quantum chemical techniques in real space reveal charge transfer from the Ba cations to the anionic Ge species. Ge atoms having nearly tetrahedral environments show an electron-localizability-based oxidation number close to 0; the four-bonded Ge atoms with a Ψ-pyramidal environment adopt a value close to 1-. In agreement with the calculated electronic density of states, the compound is a metallic conductor (electrical resistivity of ca. 240 μΩ cm at 300 K), and magnetic susceptibility measurements evidence diamagnetic behavior with χ₀ = −95 × 10^–6 emu mol^–1

Annual vertically integrated divergence moisture flux (mm/year).

<p>Values higher than 250/year are in grey, and the interval between isolines is 250 mm/year. The North Atlantic moisture source is outlined in red. Data: ERA-40 (1958–2001).</p

Synthesis, Characterization, and Photoelectric and Electrochemical Behavior of (CH₃NH₃)₂Zn_1–<i>x</i>Co_<i>x</i>Br₄ Perovskites

We report the synthesis, characterization, and photoelectric and electrochemical properties of (CH3NH3)2Zn1–xCoxBr4 (x = 0.0, 0.3, 0.5, 0.7, and 1.0) samples. X-ray powder and single-crystal diffraction confirm the formation of solid solution across the entire range. Additionally, as the cobalt concentration increases, the crystallinity of the samples decreases, as indicated by the powder diffraction patterns. All samples remain stable up to 560 K, beyond which they decompose into CH3NH3Br and the respective bromide. The semiconductor behavior of the compounds is confirmed through optical absorption measurements, and band gap values are determined by using the Tauc method from diffuse reflectance spectra. Raman spectroscopy reveals a slight redshift in all vibration modes with increasing cobalt content. Finally, photovoltaic measurements on solar cells constructed with (MA)2CoBr4 perovskite exhibit modest performance, and electrochemical measurements indicate that the compound with the composition (MA)2Zn0.3Co0.7Br4 exhibits the highest current for electrochemical water reduction during oxygen evolution

BaGe₆ and BaGe_6‑x: Incommensurately Ordered Vacancies as Electron Traps

We report the high-pressure high-temperature synthesis of the germanium-based framework compounds BaGe₆ (<i>P</i> = 15 GPa, <i>T</i> = 1073 K) and BaGe_6–<i>x</i> (<i>P</i> = 10 GPa, <i>T</i> = 1073 K) which are metastable at ambient conditions. In BaGe_6‑<i>x</i>, partial fragmentation of the BaGe₆ network involves incommensurate modulations of both atomic positions and site occupancy. Bonding analysis in direct space reveals that the defect formation in BaGe_6–<i>x</i> is associated with the establishment of free electron pairs around the defects. In accordance with the electron precise composition of BaGe_6‑<i>x</i> for <i>x</i> = 0.5, physical measurements evidence semiconducting electron transport properties which are combined with low thermal conductivity

BaGe₆ and BaGe_6‑x: Incommensurately Ordered Vacancies as Electron Traps

We report the high-pressure high-temperature synthesis of the germanium-based framework compounds BaGe₆ (<i>P</i> = 15 GPa, <i>T</i> = 1073 K) and BaGe_6–<i>x</i> (<i>P</i> = 10 GPa, <i>T</i> = 1073 K) which are metastable at ambient conditions. In BaGe_6‑<i>x</i>, partial fragmentation of the BaGe₆ network involves incommensurate modulations of both atomic positions and site occupancy. Bonding analysis in direct space reveals that the defect formation in BaGe_6–<i>x</i> is associated with the establishment of free electron pairs around the defects. In accordance with the electron precise composition of BaGe_6‑<i>x</i> for <i>x</i> = 0.5, physical measurements evidence semiconducting electron transport properties which are combined with low thermal conductivity