Oxidative Decomposition of Propylene Carbonate in Lithium Ion Batteries: A DFT Study

This paper reports an in-depth mechanistic study on the oxidative decomposition of propylene carbonate in the presence of lithium salts (LiClO₄, LiBF₄, LiPF₆, and LiAsF₆) with the aid of density functional theory calculations at the B3LYP/6-311++G­(d,p) level of theory. The solvent effect is accounted for by using the implicit solvation model with density method. Moreover, the rate constants for the decompositions of propylene carbonate have been investigated by using transition-state theory. The shortening of the original carbonyl C–O bond and a lengthening of the adjacent ethereal C–O bonds of propylene carbonate, which occurs as a result of oxidation, leads to the formation of acetone radical and CO₂ as a primary oxidative decomposition product. The termination of the primary radical generates polycarbonate, acetone, diketone, 2-(ethan-1-ylium-1-yl)-4-methyl-1,3-dioxolan-4-ylium, and CO₂. The thermodynamic and kinetic data show that the major oxidative decomposition products of propylene carbonate are independent of the type of lithium salt. However, the decomposition rate constants of propylene carbonate are highly affected by the lithium salt type. On the basis of the rate constant calculations using transition-state theory, the order of gas volume generation is: [PC-ClO₄]⁻ > [PC-BF₄]⁻ > [PC-AsF₆]⁻ > [PC-PF₆]⁻

The Secular Trends in the Incidence Rate and Outcomes of Out-of-Hospital Cardiac Arrest in Taiwan—A Nationwide Population-Based Study

<div><p>Objective</p><p>This study investigated the trends in incidence and mortality of out-of-hospital cardiac arrest (OHCA), as well as factors associated with OHCA outcomes in Taiwan.</p><p>Methods</p><p>Our study included OHCA patients requiring cardiopulmonary resuscitation (CPR) upon arrival at the hospital. We used national time-series data on annual OHCA incidence rates and mortality rates from 2000 to 2012, and individual demographic and clinical data for all OHCA patients requiring mechanical ventilation (MV) care from March of 2010 to September of 2011. Analytic techniques included the time-series regression and the logistic regression.</p><p>Results</p><p>There were 117,787 OHCAs in total. The overall incidence rate during the 13 years was 51.1 per 100,000 persons, and the secular trend indicates a sharp increase in the early 2000s and a decrease afterwards. The trend in mortality was also curvilinear, revealing a substantial increase in the early 2000s, a subsequent steep decline and finally a modest increase. Both the 30-day and 180-day mortality rates had a long-term decreasing trend over the period (p<0.01). For both incidence and mortality rates, a significant second-order autoregressive effect emerged. Among OHCA patients with MV, 1-day, 30-day and 180-day mortality rates were 31.3%, 75.8%, and 86.0%, respectively. In this cohort, older age, the female gender, and a Charlson comorbidity index score ≥ 2 were associated with higher 180-day mortality; patients delivered to regional hospitals and those residing in non-metropolitan areas had higher death risk.</p><p>Conclusions</p><p>Overall, both the 30-day and the 180-day mortality rates after OHCA had a long-term decreasing trend, while the 1-day mortality had no long-term decline. Among OHCA patients requiring MV, those delivered to regional hospitals and those residing in non-metropolitan areas tended to have higher mortality, suggesting a need for effort to further standardize and improve in-hospital care across hospitals and to advance pre-hospital care in non-metropolitan areas.</p></div

The secular trend in the OHCA mortality rate in Taiwan from 2000 to 2012 (%), by age and survival time.

<p>^&p<0.05;</p><p>^#p<0.01;</p><p>*p<0.001.</p><p>Abbreviations: CI, confidence interval; Coef., coefficient; Int., intercept; MR, mortality rate; OHCA, out-of-hospital cardiac arrest.</p><p>^aFor the year 2000, t = 0; t = 1 for the year 2001, t = 2 for the year 2002, and so on. The models include lags of 1, 2 and 3 of the structural disturbance.</p><p>^bσ is <i>the estimated standard deviation of the white-noise disturbance</i>.</p><p>The secular trend in the OHCA mortality rate in Taiwan from 2000 to 2012 (%), by age and survival time.</p

The secular trend in the OHCA incidence rate in Taiwan (the number of cases per 100,000 persons), for national data of Taiwan from 2000 to 2012, by gender.

<p>^* p<0.05;</p><p>^**p<0.01;</p><p>^***p<0.001.</p><p>Abbreviations: CI, confidence interval; IR, incidence rate; OHCA, out-of-hospital cardiac arrest.</p><p>^aFor the year 2000, t = 0; t = 1 for the year 2001, t = 2 for the year 2002, and so on. The models include lags of 1, 2 and 3 of the structural disturbance.</p><p>^bσ is <i>the estimated standard deviation of the white-noise disturbance</i>.</p><p>The secular trend in the OHCA incidence rate in Taiwan (the number of cases per 100,000 persons), for national data of Taiwan from 2000 to 2012, by gender.</p

Total numbers of incidents with out-of-hospital cardiac arrest and incident rates, for women.

<p>Total numbers of incidents with out-of-hospital cardiac arrest and incident rates, for women.</p

The selection process of study subjects with out-of-hospital cardiac arrest requiring cardiopulmonary resuscitation upon arrival.

<p>The selection process of study subjects with out-of-hospital cardiac arrest requiring cardiopulmonary resuscitation upon arrival.</p

1-day mortality rates of out-of-hospital cardiac arrest, for both genders combined and by gender.

<p>1-day mortality rates of out-of-hospital cardiac arrest, for both genders combined and by gender.</p

30-day mortality rates of out-of-hospital cardiac arrest, for both genders combined and by gender.

<p>30-day mortality rates of out-of-hospital cardiac arrest, for both genders combined and by gender.</p

Factors associated with 1-day, 1-month and 6-month mortality rates among OHCA patients requiring MV care during the hospital stay: logistic regression models that adopt a robust variance estimator adjusting for hospital-level intra-group correlation.

<p>^* p<0.05;</p><p>^** p<0.01;</p><p>^*** p<0.001.</p><p>Abbreviations: CI, confidence interval; MV, mechanical ventilation; OHCA, out-of-hospital cardiac arrest; OR, odds ratio.</p><p>Factors associated with 1-day, 1-month and 6-month mortality rates among OHCA patients requiring MV care during the hospital stay: logistic regression models that adopt a robust variance estimator adjusting for hospital-level intra-group correlation.</p

The secular trend in the OHCA mortality rate (%), for national data of Taiwan from 2000 to 2012, by gender and survival time.

<p>^&p<0.05;</p><p>^#p<0.01;</p><p>^*p<0.001.</p><p>Abbreviations: CI, confidence interval; Coef., coefficient; Int., intercept; MR, mortality rate; OHCA, out-of-hospital cardiac arrest.</p><p>^aFor the year 2000, t = 0; t = 1 for the year 2001, t = 2 for the year 2002, and so on. The models include lags of 1, 2 and 3 of the structural disturbance.</p><p>^bσ is <i>the estimated standard deviation of the white-noise disturbance</i></p><p>The secular trend in the OHCA mortality rate (%), for national data of Taiwan from 2000 to 2012, by gender and survival time.</p