Lithium-ion batteries are a central technology to our daily lives with widespread use in mobile devices and electric vehicles. These batteries are also beginning to be widely used in electric grid infrastructure support applications which have stringent safety and reliability requirements. Typically, electrochemical performance data is not available for modelers to validate their simulations, mechanisms, and algorithms for lithium-ion battery performance and lifetime. In this paper, we report on the electrochemical performance of commercial 18650 cells at a variety of temperatures and discharge currents. We found that LiFePO4 is temperature tolerant for discharge currents at or below 10 A whereas LiCoO2, LiNixCoyAl1-x-yO2, and LiNi0.80Mn0.15Co0.05O2 exhibited optimal electrochemical performance when the temperature is maintained at 15°C. LiNixCoyAl1-x-yO2 showed signs of lithium plating at lower temperatures, evidenced by irreversible capacity loss and emergence of a high-voltage differential capacity peak. Furthermore, all cells need to be monitored for self-heating, as environment temperature and high discharge currents may elicit an unintended abuse condition. Overall, this study shows that lithium-ion batteries are highly application-specific and electrochemical behavior must be well understood for safe and reliable operation. Additionally, data collected in this study is available for anyone to download for further analysis and model validation.
7 October 2017 in Journal of the Electrochemical Society
While the low cost and strong safety record of lead-acid batteries make them an appealing option compared to lithium-ion technologies for stationary storage, they can be rapidly degraded by the extended periods of high rate, partial state-of-charge operation required in such applications. Degradation occurs primarily through a process called hard sulfation, where large PbSO4 crystals are formed on the negative battery plates, hindering charge acceptance and reducing battery capacity. Various researchers have found that the addition of some forms of excess carbon to the negative active mass in lead-acid batteries can mitigate hard sulfation, but the mechanism through which this is accomplished is unclear. In this work, the effect of carbon composition and morphology was explored by characterizing four discrete types of carbon additives, then evaluating their effect when added to the negative electrodes within a traditional valve-regulated lead-acid battery design. The cycle life for the carbon modified cells was significantly larger than an unmodified control, with cells containing a mixture of graphitic carbon and carbon black yielding the greatest improvement. The carbons also impacted other electrochemical aspects of the battery (e.g., float current, capacity, etc.) as well as physical characteristics of the negative active mass, such as the specific surface area.
In this work, 114 volunteers were dosed with 80-proof liquor to produce peak blood-alcohol concentration (BAC) or breath-alcohol concentration (BrAC) of 0.040–0.080 g/100 mL blood or g/210 L breath. This was followed by a 30 minute deprivation period before simultaneous blood and breath samples were collected and the alcohol concentration quantified. BAC was determined by gas chromatography with flame ionization detection and BrAC by a dual-sensor Intox EC/IR II instrument. Paired Student t-tests showed that differences between paired blood- and breath-alcohol results differed significantly. Results from these two measurement methods are highly correlated and, on average, measured BAC was 11.3% greater than BrAC. There were 10 instances of BrAC being greater than the corresponding BAC, and the average difference between these two values was 0.0059 g/100 mL. Agreement plots of coupled BAC and BrAC revealed a mean bias of 0.00754 g/100 mL and 95% limits of agreement (LOA) at −0.00705 and 0.0221 g/100 mL. Once BrAC values were truncated to the hundredths place as required by Wisconsin state statute, only three participants had greater BrAC than corresponding BAC, with an average difference between these values of 0.008 g/100 mL. Agreement plots with truncated BrAC values gave a mean bias of 0.0120 g/100 mL and 95% LOA at −0.00344 and 0.0275 g/100 mL. Data showed that typically, blood samples had greater alcohol concentrations than corresponding breath values. Differences were exacerbated by Wisconsin’s statutory requirement that reported breath alcohol measurements be truncated to the hundredths place, whereas blood has no corresponding mandate.
13 June 2023 in ACS Pharmacology & Translational Science
Little is known about the demographics of people who use cannabis, including how use trends within population subgroups have evolved over time. It is therefore challenging to know if the demographics of participants enrolled in cannabis clinical trials are representative of those who use cannabis. To fill this knowledge gap, data from the National Survey on Drug Use and Health (NSDUH) on “past-month” cannabis use across various population subgroups in the United States was examined from 2002 to 2021. The most notable increases in “past-month” cannabis use prevalence occurred in those aged 65 and older (2,066.1%) and 50–64-year-olds (472.4%). In 2021, people reporting “past-month” cannabis use were 56.6% male and 43.4% female. Distribution across self-reported race and ethnicity was 64.1% White, 14.3% Black, 14.1% Hispanic, and 3.1% more than one race. And many ages were represented as 24.4% were 26–34, 24.1% were 35–49, 22.4% were 18–25, and 17.6% were 50–64 years old. To understand if these population subgroups are represented in cannabis clinical trials, participant demographics were extracted from peer-reviewed clinical trials reporting on pharmacokinetic and/or pharmacodynamic models of cannabis or cannabinoids. Literature was grouped by publication year (2000–2014 and 2015–2022) and participant prior exposure to cannabis. Results identified that cannabis clinical trial participants are skewed toward overrepresentation by White males in their 20s and 30s. This represents structural discrimination in the research landscape that perpetuates social and health inequities.