Anchored Mediator Enabling Shuttle-Free Redox Mediation in Lithium-Oxygen Batteries.

Redox mediators (RMs) are considered an effective countermeasure to reduce the large polarization in lithium-oxygen batteries. Nevertheless, achieving sufficient enhancement of the cyclability is limited by the trade-offs of freely mobile RMs, which are beneficial for charge transport but also trigger the shuttling phenomenon. Here, we successfully decoupled the charge-carrying redox property of RMs and shuttling phenomenon by anchoring the RMs in polymer form, where physical RM migration was replaced by charge transfer along polymer chains. Using PTMA (poly(2,2,6,6-tetramethyl-1-piperidinyloxy-4-yl methacrylate)) as a polymer model system based on the well-known RM tetramethylpiperidinyloxyl (TEMPO), it is demonstrated that PTMA can function as stationary RM, preserving the redox activity of TEMPO. The efficiency of RM-mediated Li2 O2 decomposition remains remarkably stable without the consumption of oxidized RMs or degradation of the lithium anode, resulting in an improved performance of the lithium-oxygen cell.

Reaction chemistry in rechargeable Li-O2 batteries.

The seemingly simple reaction of Li-O2 batteries involving lithium and oxygen makes this chemistry attractive for high-energy-density storage systems; however, achieving this reaction in practical rechargeable Li-O2 batteries has proven difficult. The reaction paths leading to the final Li2O2 discharge products can be greatly affected by the operating conditions or environment, which often results in major side reactions. Recent research findings have begun to reveal how the reaction paths may be affected by the surrounding conditions and to uncover the factors contributing to the difficulty in achieving the reactions of lithium and oxygen. This progress report describes the current state of understanding of the electrode reaction mechanisms in Li-O2 batteries; the factors that affect reaction pathways; and the effect of cell components such as solvents, salts, additives, and catalysts on the discharge product and its decomposition during charging. This comprehensive review of the recent progress in understanding the reaction chemistry of the Li-O2 system will serve as guidelines for future research and aid in the development of reliable high-energy-density rechargeable Li-O2 batteries.

A New Perspective on Li-SO2 Batteries for Rechargeable Systems.

Primary Li-SO2 batteries offer a high energy density in a wide operating temperature range with exceptionally long shelf life and have thus been frequently used in military and aerospace applications. Although these batteries have never been demonstrated as a rechargeable system, herein, we show that the reversible formation of Li2S2O4, the major discharge product of Li-SO2 battery, is possible with a remarkably smaller charging polarization than that of a Li-O2 battery without the use of catalysts. The rechargeable Li-SO2 battery can deliver approximately 5400 mAh g(-1) at 3.1 V, which is slightly higher than the performance of a Li-O2 battery. In addition, the Li-SO2 battery can be operated with the aid of a redox mediator, exhibiting an overall polarization of less than 0.3 V, which results in one of the highest energy efficiencies achieved for Li-gas battery systems.

Superior rechargeability and efficiency of lithium-oxygen batteries: hierarchical air electrode architecture combined with a soluble catalyst.

The lithium-oxygen battery has the potential to deliver extremely high energy densities; however, the practical use of Li-O2 batteries has been restricted because of their poor cyclability and low energy efficiency. In this work, we report a novel Li-O2 battery with high reversibility and good energy efficiency using a soluble catalyst combined with a hierarchical nanoporous air electrode. Through the porous three-dimensional network of the air electrode, not only lithium ions and oxygen but also soluble catalysts can be rapidly transported, enabling ultra-efficient electrode reactions and significantly enhanced catalytic activity. The novel Li-O2 battery, combining an ideal air electrode and a soluble catalyst, can deliver a high reversible capacity (1000 mAh g(-1) ) up to 900 cycles with reduced polarization (about 0.25 V).

Younger Older Americans and Sarcopenic Obesity: The Moderating Role of Living Alone.

OBJECTIVES: Previous studies have indicated that compared to older adults, younger older adults (e.g., baby boomers) are more susceptible to obesity, but their risk decreases as they age. However, there is a lack of research on how individuals experience sarcopenic obesity, which increases in later life and is a mortality risk factor. This study examined how younger cohorts of older Americans and their demographic traits are related to sarcopenic obesity. METHODS: Generalized estimating equations were used to analyze participants aged 65 years and older, stratified by sex using data from the 2006-2016 Health and Retirement Study, with survey weights (n = 2,896 men and n = 4,268 women). RESULTS: The findings indicate that the youngest cohort (born between 1948 and 1953) had greater odds of sarcopenic obesity than older cohorts (born before 1931). However, the youngest cohort did not have significantly different risks from those born between 1931 and 1947. Unexpectedly, the youngest cohort of older women living alone tended not to have sarcopenic obesity compared to the older cohorts living alone. These results remained significant even after adjusting for various covariates, including marital status, race, education level, wealth, and other factors. DISCUSSION: This paper contributes to the existing literature on population health and demographic change in 2 ways. First, the risk of sarcopenic obesity is higher among younger cohorts of older Americans relative to older cohorts (born before 1931). Second, living alone may not necessarily be considered a worse health condition, particularly for younger female cohorts.

Social isolation and depression as risk factors for weight loss of 5kg or more among older Korean adults.

Given a well-known overlapping prevalence of social isolation with loneliness and depression among older adults, this study aimed to contextually investigate the relationship of these constructs with weight loss of more than 5kg in a year, with a special focus on the intersection of living alone and marital dissolution as key dimensions of isolation. The data were obtained from the Korean Longitudinal Study of Aging (KLoSA) from 2006, 2008, 2010, 2012, 2014, 2016, and 2018, with an adult sample of those aged 65 and older (n = 5,481). The study evaluated several critical dimensions of social isolation: living alone, transition to living alone, infrequent social contact with children or friends, and infrequent social participation. These dimensions were examined individually and as a composite scale, along with loneliness and depressive symptoms, to determine their association with weight loss of 5kg or greater among older men and women. Generalized Estimating Equation (GEE) regression models enabled investigation of whether socially isolated men and women tended to lose 5kg or more in weight, given other confounding factors. Surprisingly, the results showed no evidence of such a trend. However, significant associations were found between weight loss and changes in living alone and marital status. For older men, transitioning to living alone without a change in marital status was linked to significant weight loss. For older women, transitioning to living alone following widowhood or divorce was the risk factor. These relationships remained significant even after adjusting for depression and a wide range of covariates. Additional analysis testing a cumulative effect revealed that only depression was a risk factor for being underweight at the last observation. Therefore, to prevent a clinically risky extent of weight loss, health policies for older Koreans should focus on those who transition to living alone, especially due to spousal bereavement or divorce (among women) and separation from living with children (among men).

Why is Korean girls' suicidal ideation rate higher than boys' rate? The role of gender heterogeneity in peer groups.

Girls typically show much lower suicide rates than boys in most OECD countries. However, in South Korea, the suicide rate of girls almost reaches that of boys. Moreover, Korean girls' suicide rate is remarkable even among other advanced countries. One potential approach to explaining Korean girls' relatively high suicide rate is to investigate how their peer groups affect suicidal ideation, but this approach has rarely been explored in Korean adolescents. We tested how the gender heterogeneity of peer groups is associated with suicidal ideation by analyzing 2,990 adolescents from the 2018 Korean Children and Youth Well-Being Index Survey. For the analysis, logistic regression models with survey weights were used. The analysis revealed that adolescents with different-gender friends were associated with a higher likelihood of suicidal ideation than those with exclusively same-gender friends when adjusting for covariates. In addition, an analysis stratified by gender found that this association was significant only among girls. Furthermore, the protective power of having a mentor against suicidal ideation was significantly lower in girls with male and female friends than in girls with only female friends. The findings suggest a less protective role of different-gender peer groups for suicidal ideation among girls. During adolescent suicidality consultations, school counselors and practitioners should pay attention to the characteristics of adolescents' peers, particularly their gender.

Evaluation of Family and Community Social Network Characteristics Among High-Risk Family Members to Improve Cancer-Related Health Behaviors.

OBJECTIVES: To evaluate the effects of social network characteristics of individuals with a family history of cancer on the use of cancer-related services (e.g., screening, genetic counseling/testing). SAMPLE & SETTING: 170 family members of individuals with the most common hereditary or familial cancers. METHODS & VARIABLES: Data collection occurred between March and September 2021 using an online survey. RESULTS: Having strong within-immediate family relationships and family members who underwent more screening procedures was associated with increased breast cancer screening, and having more family members with cancer was associated with colorectal cancer screening. Having a large family, having family members who underwent screening for more cancers, and having strong social cohesion among families were associated with an increased rate of genetic testing. IMPLICATIONS FOR NURSING: Nurses working with families affected by cancer should focus on strategies to strengthen relationships among family members to improve knowledge of cancer screening and available genetic services.

High-efficiency and high-power rechargeable lithium-sulfur dioxide batteries exploiting conventional carbonate-based electrolytes.

Shedding new light on conventional batteries sometimes inspires a chemistry adoptable for rechargeable batteries. Recently, the primary lithium-sulfur dioxide battery, which offers a high energy density and long shelf-life, is successfully renewed as a promising rechargeable system exhibiting small polarization and good reversibility. Here, we demonstrate for the first time that reversible operation of the lithium-sulfur dioxide battery is also possible by exploiting conventional carbonate-based electrolytes. Theoretical and experimental studies reveal that the sulfur dioxide electrochemistry is highly stable in carbonate-based electrolytes, enabling the reversible formation of lithium dithionite. The use of the carbonate-based electrolyte leads to a remarkable enhancement of power and reversibility; furthermore, the optimized lithium-sulfur dioxide battery with catalysts achieves outstanding cycle stability for over 450 cycles with 0.2 V polarization. This study highlights the potential promise of lithium-sulfur dioxide chemistry along with the viability of conventional carbonate-based electrolytes in metal-gas rechargeable systems.

Dissolution and ionization of sodium superoxide in sodium-oxygen batteries.

With the demand for high-energy-storage devices, the rechargeable metal-oxygen battery has attracted attention recently. Sodium-oxygen batteries have been regarded as the most promising candidates because of their lower-charge overpotential compared with that of lithium-oxygen system. However, conflicting observations with different discharge products have inhibited the understanding of precise reactions in the battery. Here we demonstrate that the competition between the electrochemical and chemical reactions in sodium-oxygen batteries leads to the dissolution and ionization of sodium superoxide, liberating superoxide anion and triggering the formation of sodium peroxide dihydrate (Na2O2·2H2O). On the formation of Na2O2·2H2O, the charge overpotential of sodium-oxygen cells significantly increases. This verification addresses the origin of conflicting discharge products and overpotentials observed in sodium-oxygen systems. Our proposed model provides guidelines to help direct the reactions in sodium-oxygen batteries to achieve high efficiency and rechargeability.