Thermal Effect and Mechanism Analysis of Flame-Retardant Modified Polymer Electrolyte for Lithium-Ion Battery.

In recent years, the prosperous electric vehicle industry has contributed to the rapid development of lithium-ion batteries. However, the increase in the energy density of lithium-ion batteries has also created more pressing safety concerns. The emergence of a new flame-retardant material with the additive ethoxy (pentafluoro) cyclotriphosphazene can ameliorate the performance of lithium-ion batteries while ensuring their safety. The present study proposes a new polymer composite flame-retardant electrolyte and adopts differential scanning calorimetry (DSC) and accelerating rate calorimetry to investigate its thermal effect. The study found that the heating rate is positively correlated with the onset temperature, peak temperature, and endset temperature of the endothermic peak. The flame-retardant modified polymer electrolyte for new lithium-ion batteries has better thermal stability than traditional lithium-ion battery electrolytes. Three non-isothermal methods (Kissinger; Kissinger-Akahira-Sunose; and Flynn-Wall-Ozawa) were also used to calculate the kinetic parameters based on the DSC experimental data. The apparent activation energy results of the three non-isothermal methods were averaged as 54.16 kJ/mol. The research results can provide valuable references for the selection and preparation of flame-retardant additives in lithium-ion batteries.

Thermal Stability Analysis of Lithium-Ion Battery Electrolytes Based on Lithium Bis(trifluoromethanesulfonyl)imide-Lithium Difluoro(oxalato)Borate Dual-Salt.

Lithium-ion batteries with conventional LiPF6 carbonate electrolytes are prone to failure at high temperature. In this work, the thermal stability of a dual-salt electrolyte of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium difluoro(oxalato)borate (LiODFB) in carbonate solvents was analyzed by accelerated rate calorimetry (ARC) and differential scanning calorimetry (DSC). LiTFSI-LiODFB dual-salt carbonate electrolyte decomposed when the temperature exceeded 138.5 °C in the DSC test and decomposed at 271.0 °C in the ARC test. The former is the onset decomposition temperature of the solvents in the electrolyte, and the latter is the LiTFSI-LiODFB dual salts. Flynn-Wall-Ozawa, Starink, and autocatalytic models were applied to determine pyrolysis kinetic parameters. The average apparent activation energy of the dual-salt electrolyte was 53.25 kJ/mol. According to the various model fitting, the thermal decomposition process of the dual-salt electrolyte followed the autocatalytic model. The results showed that the LiTFSI-LiODFB dual-salt electrolyte is significantly better than the LiPF6 electrolyte in terms of thermal stability.

Stereoselective synthesis of enamino ketones through an aza-Michael/hydrolysis cascade reaction.

We have developed a mild, convenient and efficient synthesis of highly functionalized (Z)-ß-enamino ketones from readily available 3,4-dihydroisoquinoline imines and ynones through an aza-Michael/hydrolysis cascade reaction. This method is also suitable for the preparation of (Z)-ß-enamino esters using alkynoates as starting materials. Complex fully substituted pyrroles can be constructed from the obtained (Z)-ß-enamino ketones. It is an attractive alternative approach for the preparation of highly functionalized enamino ketones, esters and pyrroles.

Catalyst-free synthesis of novel dimeric ß-carboline derivatives via an unexpected [2 + 2 + 2] annulation.

We report here an unexpected catalyst-free [2 + 2 + 2] annulation reaction which allows access to novel complex dimeric ß-carboline derivatives in a single step. Various substituted ynones could react with dihydro-ß-carboline imines to deliver interesting [2 + 2 + 2] annulation products in moderate to good yields. Alkynoates can also be tolerated in this system.

[Impact on calcification of aortic arch by lifestyle-related, physiologic and biochemical factors].

OBJECTIVE: To explore the impact of lifestyle-related, physiological and biochemical factors on aortic arch calcification (AAC). METHODS: 20 430 subjects aged 50 to 85 years were included in this study from the first and second recruitment phase of the Guangzhou Biobank Cohort Study. All the subjects received face-to-face interviews to collect detailed information on their socio-demographic background, occupational exposures, living environment, lifestyle, family and personal disease histories, and received a physical examination and tests including 12-lead ECG, chest radiograph, and pulmonary function testing. Each subject was screened for a range of fasting biochemical parameters. Radiographs were reviewed by two senior radiologists. 300 radiographs were independently read by the two radiologists to assess agreement using Kappa coefficient. Logistic regression was used to assess the association between life style, physiological and biochemical factors and AAC. RESULTS: (1) The rate of agreement on diagnosis for the two radiologists was 85% and Kappa coefficient was 0.68 (P < 0.01) which showed a moderate agreement between the two radiologists. (2) Except hypertension, the subjects were significantly different on their lifestyle, physiological and biochemical factors in both men and women (P < 0.05). (3) AAC was significantly associated with older age, smoking status, LDL-C, and hypertension (P < 0.01) in both genders. ORs (95%CI) indicated the following results: age was 1.11 (1.10 - 1.12) in men and 1.12 (1.12 - 1.13) in women;smoking as 1.31 (1.17 - 1.47) in men and 1.31 (1.09 - 1.57) in women; LDL-C as 1.16 (1.06 - 1.27) in men and 1.38 (1.22 - 1.56) in women, hypertension as 1.33 (1.18 - 1.50) in men and 1.27 (1.18 - 1.38) in women. However, diabetes was found to be associated with an increased risk of AAC in women [OR(95%CI)] 1.38 (1.22 - 1.56). CONCLUSION: Age, smoking, hypertension and Low-density lipoprotein level were risk factors to both genders, on AAC, while diabetes increased the risk of AAC, in women.

Evidence for altered hippocampal volume and brain metabolites in workers occupationally exposed to lead: a study by magnetic resonance imaging and (1)H magnetic resonance spectroscopy.

Environmental and occupational exposure to lead (Pb) remains to be a major public health issue. The purpose of this cross-sectional study was to use non-invasive magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy ((1)H MRS) techniques to investigate whether chronic exposure to Pb in an occupational setting altered brain structure and function of Pb-exposed workers. The Pb-exposed group consisted of 15 workers recruited from either a Pb-smelting factory or a Pb-battery manufacturer. The control group had 19 healthy volunteers who had no history of Pb exposure in working environment or at home. The average airborne Pb concentrations in fume and dust were 0.43 and 0.44 mg/m(3), respectively, in the smeltery, and 0.10 and 1.06 mg/m(3), respectively, in the Pb battery workshop. The average blood Pb concentrations (BPb) in Pb-exposed and control workers were 63.5 and 8.7 microg/dL, respectively. The MRI examination showed that brain hippocampal volume among Pb-exposed workers was significantly diminished in comparison to age-matched control subjects (p < 0.01), although the extent of this reduction was relatively small (5-6% of the control values). Linear regression analyses revealed significant inverse associations between BPb and the decreased hippocampal volume on both sides of brain hemisphere. Among five brain metabolites investigated by MRS, i.e., N-acetyl-aspartate (NAA), creatine (Cr), choline (Cho), inosine (mI), glutamate/glutamine (Glx) and lipids (Lip), a significant decrease in NAA/Cr ratio (7% of controls, p < 0.05) and a remarkable increase in Lip/Cr ratio (40%, p < 0.01) were observed in the brains of Pb-exposed workers as compared to controls. Furthermore, the increased Lip/Cr ratio was significantly associated with BPb (r = 0.46, p < 0.01). Taken together, this study suggests that occupational exposure to Pb may cause subtle structural and functional alteration in human brains. The MRI and MRS brain imaging techniques can be used as the non-invasive means to evaluate Pb-induced neurotoxicity.