ABSTRACT
Due to a national shortage of child and adolescent psychiatrists, pediatric primary care providers (PCPs) are often responsible for the screening, evaluation, and treatment of mental health disorders. COVID-19 pandemic stay-at-home orders decreased access to mental health care and increased behavioral and emotional difficulties in children and adolescents. Despite increased demand upon clinicians, little is known about mental health care delivery in the pediatric primary care setting during the pandemic. This focus group study explored the experiences of pediatric PCPs and clinical staff delivering mental health care during the pandemic. Transcripts from nine focus groups with San Francisco Bay Area primary care practices between April and August 2020 were analyzed using a thematic analysis approach. Providers expressed challenges at the patient-, provider-, and system-levels. Many providers reported increased patient mental health symptomatology during the pandemic, which was often intertwined with patients' social determinants of health. Clinicians discussed the burden of the pandemic their own wellness, and how the rapid shift to telehealth primary care and mental health services seemed to hinder the availability and effectiveness of many resources. The findings from this study can inform the creation of new supports for PCPs and clinical staff providing mental health care.
ABSTRACT
Metal oxide coatings have been reported to be an effective approach for stabilizing cathode interfaces, but the associated chemistry is unclear. In this work, thin films of TiO2, ZnO, and Cr2O3, which have different surface acidities/basicities, were used to modify the surface chemistry of LiNi0.6Mn0.2Co0.2O2 and study the acidity's role in the cathode/electrolyte interphase composition and impedance under high-voltage cycling (4.5 V vs Li/Li+). Cathodes with more acidic surfaces provided higher initial specific capacity and capacity retention with cycling. More basic surfaces had higher initial impedance and greater impedance growth with cycling. These differences appeared to depend on the degree of LiPF6 salt decomposition at the interface, which was related to acidity, with more neutral surfaces having a LiF/Li x PO y F z ratio close to unity, but basic surfaces had substantially more LiF. This chemistry was more significant than the cathode electrolyte interphase (CEI) thickness as the more acidic surfaces formed a thicker CEI than the basic surface, resulting in better capacity retention. These results suggest that the Brønsted acidity of cathodes directly influences electrolyte degradation, ion transport, and thus, cell lifetime.
ABSTRACT
Lithium phosphorus oxynitride, also known as Lipon, solid-state electrolytes are at the center of the search for solid-state Li metal batteries. Key to the performance of Lipon is a combination of high Li content, amorphous character, and the incorporation of N into the structure. Despite the material's importance, our work presents the first study to fully resolve the structure of Lipon using a combination of ab initio molecular dynamics, density functional theory, neutron scattering, and infrared spectroscopy. The modeled and experimental results have exceptional agreement in both neutron pair distribution function and infrared spectroscopy. Building on this synergy, the structural models show that N forms both bridges between two phosphate units and nonbridging apical N. We further show that as the Li content is increased the ratio of bridging to apical N shifts from being predominantly bridging at Li contents around 2.5:1 Li:P to only apical N at higher Li contents of 3.38:1 Li:P. This crossover from bridging to apical N appears to directly correlate with and explain both the increase in ionic conductivity with the incorporation of N and the ionic conductivity trends found in the literature.
