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With the number of smartphone users growing around the world, children are using smartphones from an increasingly early age. Consequently, a significant number of children are being exposed to the risk of smartphone addiction, which is emerging as a serious social problem. Smartphone addiction can negatively impact children’s physical, cognitive, and social development. Previous studies have demonstrated that parental smartphone addiction influences that of their children. Therefore, this study explores the relationship between parental smartphone addiction and children’s smartphone addiction and the mediating effects of children’s depression and social withdrawal. Data are drawn from National Youth Policy Institute’s 2018 Korean Children and Youth Panel Survey. Respondents comprise 2011 fourth-grade elementary school students and their parents. Data were analyzed using SPSS version 21.0 and AMOS 21.0 software. Results show that the relationship between parental smartphone addiction and that of their children has a significantly positive mediating effect on children’s social withdrawal, but no such effect on children’s depression and there were no serial effects of children’s depression and social withdrawal. Consequently, educational programs that control parents’ smartphone usage, improve the parent–child relationship, and engender social sensitivity should be developed to reduce and prevent smartphone addiction among children.

Breakfast consumption is essential for children to generate energy for the day. Parents play an important role in children’s breakfast habits and spending time with parents during breakfast greatly influences children’s emotional development. Therefore, this study investigated the relationship between the frequency of children’s breakfast consumption, time spent in conversation with parents, and children’s somatic symptoms. Data were obtained from the Korea Children and Youth Panel Survey 2018 and were initially collected from fourth-grade elementary school students and followed up for three years. SPSS 21.0 and AMOS 21.0 software were used for data analysis. Multivariate latent growth modeling was applied to analyze the effect of the breakfast consumption frequency on children’s somatic symptoms and the mediating effect of parent–child conversation time on this relationship. Consequently, as children’s frequency of breakfast consumption increased, their somatic symptoms decreased. Furthermore, parent–child conversation time mediated the relationship between these two variables. Therefore, students, parents, and teachers should be educated about the importance of having breakfast and communicating with parents for students’ emotional health.

The development of COVID-19 vaccines is critical in controlling global health issues under the COVID-19 pandemic. The subunit vaccines are the safest and most widely used vaccine platform and highly effective against a multitude of infectious diseases. An adjuvant is essential for subunit vaccines to enhance the magnitude and durability of immune responses. In this study, we determined whether a combination of toll-like receptor (TLR)1/2 and TLR3 agonists (L-pampo) can be a potent adjuvant for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) subunit vaccine. We measured a neutralizing antibody (nAb) and an angiotensin-converting enzyme 2 (ACE2) receptor-blocking antibody against SARS-CoV-2 receptor-binding domain (RBD). We also detected interferon-gamma (IFN-γ) production by using ELISPOT and ELISA assays. By employing a ferret model, we detected nAbs and IFN-γ producing cells and measured viral load in nasal wash after the challenge of SARS-CoV-2. We found that SARS-CoV-2 antigens with L-pampo stimulated robust humoral and cellular immune responses. The efficacy of L-pampo was higher than the other adjuvants. Furthermore, in the ferret model, SARS-CoV-2 antigens with L-pampo elicited nAb response and antigen-specific cellular immune response against SARS-CoV-2, resulting in substantially decreased viral load in their nasal wash. Our study suggests that SARS-CoV-2 antigens formulated with TLR agonists, L-pampo, can be a potent subunit vaccine to promote sufficient protective immunity against SARS-CoV-2.

Although the global prevalence of childhood sexual abuse (CSA) is very high, the experience of healing after such abuse has not been well documented. The goal of this study was to characterize the healing experience among CSA survivors presented in the literature. Metaethnography was used to synthesize an integrative literature review. The CINAHL, PubMed, PsycINFO, and Web of Science databases were used as data sources. Eight articles that explored healing experiences from CSA, published between 2007 and 2017, were included in the analysis. After performing a quality assessment, line-of-argument synthesis was used to construct the integrating scheme of healing experiences from CSA. CSA healing experiences included dissociating oneself from the memories of CSA, finding peace by creating a comfort zone, disclosure as the start of healing, attempting to establish identity through ongoing self-reflective activities, feeling comfort by sharing experiences and connecting with CSA survivors, and accepting CSA as part of the life history and stepping forward. Healing experiences from CSA synthesized from the analysis focused on personal growth, supporting previous theory on CSA health in the broader literature. A tailored care plan could be developed for CSA survivors who are at varying stages of healing.

The purpose of this scoping review was to explore the state of the current body of knowledge on the use of nursing simulation for maternal nursing practicum with a focus on content and measured outcomes.This is a scoping review.The literature search was performed using five databases (CINAHL, Cochrane, EMBASE, PubMed, and Web of Science).The review was conducted on quantitative and reflection/review studies that evaluated or described nursing simulation for delivery care, published between 2000 and 2020 in English and Korean. Two authors independently reviewed the studies and their references for additional literature search. Selected studies were charted to describe the study characteristics, and content and outcome of nursing simulation for delivery care.Fifteen articles were included in the review, of which twelve were intervention studies and three were reflection/review studies. The duration of the nursing simulations for delivery care ranged from 20 min to 4 h, with two to eight students in each simulation group. All nursing simulations focused on the normal, uncomplicated delivery process, with nine studies engaging in debriefing, but without pre- and/or post-assessments. The most frequently measured outcomes were knowledge, satisfaction, and clinical practice competency.Studies investigating nursing simulation pedagogy for delivery care were scarce, with limitations in the study designs and large variations in nursing simulation time across studies. Scenarios for nursing simulation for delivery care were rudimentary, and they usually focused on normal uncomplicated deliveries. The development of scenarios for high-risk deliveries and integration of pre-and/or post-assessments and debriefing into the nursing simulation are recommended to improve learning outcomes.

Suicide is the topmost cause of death among adolescents in South Korea and is deeply related to depression. This study aimed to identify gender differences in the factors affecting depression among multicultural adolescents. This study is a secondary analysis using data from a national survey, the Multicultural Adolescents Panel Study (MAPS) conducted in 2017. The participants were 1160 multicultural adolescents ranging from 15 to 18 years, living in Korea, and whose fathers were Koreans and mothers were foreigners. The results showed that depression scores were higher for females (18.35) than males (16.38, t = 6.42, p &lt, 0.001). In total, seven factors affected depression among male multicultural adolescents’ and the model explained 50.5% of the total variance (F = 77.99, p &lt, 0.001), while four factors affected female multicultural adolescents’ depression, and the model explained 51.4% of the total variance (F = 100.02, p &lt, 0.001). Significant gender differences were found in factors that influence depression among multicultural adolescents. Therefore, depression prevention programs for multicultural adolescents need to vary according to gender. Additionally, these programs should target families and teachers of multicultural adolescents as well.

BACKGROUND The current body of knowledge has highlighted the potential role of mobile technology as a medium to deliver support for psychological and physical health. OBJECTIVE The purpose of this study was to evaluate the influence of support provided using mobile technology on depressive symptoms and physical activity among female university students. METHODS A mixed-methods sequential explanatory design was used to conduct a single-site, randomized controlled quantitative study followed by a qualitative study. A total of 99 participants were block randomized based on the severity of their depressive symptoms into three arms: an emotional and informational support group, an informational support group, and a control group. Interventions were delivered for two weeks. Data from 84 participants on the depressive symptoms and physical activity were collected at baseline, day 8, and day 15. Individual interviews of 24 participants from the three arms were conducted. Data analysis included descriptive statistics, t-tests, one-way ANOVA and RMANOVA for quantitative data and content analysis for qualitative data. RESULTS Although significant difference was not reported in depressive symptoms over time among three groups, depressive symptoms decreased significantly at each of the time during the intervention (F=27.83, P CONCLUSIONS Mobile technology could be used as a medium for support for depressive symptoms and physical activity in the short term. Emotional support might be a key to maintaining physical activity.

The interpretation of radiation dose is an important procedure for both radiological operators and persons who are exposed to background or artificial radiations. Dicentric chromosome assay (DCA) is one of the representative methods of dose estimation that discriminates the aberration in chromosomes modified by radiation. Despite the DCA-based automated radiation dose estimation methods proposed in previous studies, there are still limitations to the accuracy of dose estimation. In this study, a DCA-based automated dose estimation system using deep learning methods is proposed. The system is comprised of three stages. In the first stage, a classifier based on a deep learning technique is used for filtering the chromosome images that are not appropriate for use in distinguishing the chromosome; 99% filtering accuracy was achieved with 2,040 test images. In the second stage, the dicentric rate is evaluated by counting and identifying chromosomes based on the Feature Pyramid Network, which is one of the object detection algorithms based on deep learning architecture. The accuracies of the neural networks for counting and identifying chromosomes were estimated at over 97% and 90%, respectively. In the third stage, dose estimation is conducted using the dicentric rate and the dose-response curve. The accuracies of the system were estimated using two independent samples; absorbed doses ranging from 1- 4 Gy agreed well within a 99% confidential interval showing highest accuracy compared to those in previous studies. The goal of this study was to provide insights towards achieving complete automation of the radiation dose estimation, especially in the event of a large-scale radiation exposure incident.

Purpose: The aim of this study was to evaluate the influence of the mothers’ native country on influenza vaccinations in adolescents in multicultural families. Methods: Data were gathered from the 13th (2017) Youth Risk Behavior Web-Based Survey. Logistic regression analyses were conducted using a complex sample data analysis method. The participants in this study had a father who was born in Korea and a mother born outside of Korea. The sample included 481 adolescents. Results: The analysis of non-adjusted confounding variables showed that influenza vaccination was higher in multicultural adolescents whose mother’s native country had an annual minimum temperature less than 21°C (odds ratio [OR]: 1.81, 95% confidence interval [CI]: 1.20~2.74). Furthermore, when the analysis was adjusted for confounding variables, an annual minimum temperature less than 21°C in the mother’s native country had a statistically significant association with influenza vaccination (OR: 2.12, 95% CI: 1.36~3.29). Conclusion: Multicultural adolescents belong to a socioeconomically vulnerable class, and their health promotion behaviors are influenced by their mothers’ culture. Thus, healthcare providers and school nurses should provide adolescents with appropriate information related to influenza vaccination depending on their mothers’ culture and their family’s cultural background.

Compared to the graphite anode, Si and SiOx-containing anodes usually have a larger initial capacity loss (ICL) due to more parasitic reactions. The higher ICL of the anode can cause significant Li inventory loss in a full cell, leading to a compromised energy density. As one way to mitigate such Li inventory loss, Li2O2 can be used as the cathode prelithiation additive to provide additional lithium. However, an additional catalyst is usually needed to lower its decomposition potential. In this work, we investigate the use of Li2O2 as the cathode prelithiation additive without the addition of a catalyst. Li2O2 decomposition is first demonstrated in coin half-cells with a calculated capacity of 1180 mAh g−1 obtained from Li2O2 decomposition. We then further demonstrate successful Li2O2 decomposition in single-layer pouch (SLP) full cells and evaluate the initial electrochemical performance. Despite its moisture sensitivity, Li2O2 showed reasonable compatibility with dry-room handling. After dry-room handling, Li2O2 decomposition was observed with an onset potential of 4.29 V vs SiOx anode in SLP cells. With Li2O2 addition, the utilization of the Li inventory from cathode active material was improved by 12.9%, and discharge DCR was reduced by 7% while the cells still delivered similar cell capacities. Cycle performance is not evaluated in this paper due to the high cutoff voltage used, but the factors affecting the cycle performance are discussed. Strategies to further improve the practical use of Li2O2 are also discussed.

Objective: This study aimed to compare the effectiveness of adolescents’ use of smartphone applications and educational booklets in an educational programme about sexually transmitted infections (STIs). Design: Non-equivalent control-group time-series design. Setting: The study was conducted in two public high schools located in two urban areas of South Korea. Methods: The following measures were developed using Roger’s protection-motivation theory as the study’s conceptual framework: STI knowledge, STI vulnerability, STI prevention self-efficacy and STI prevention intentions. Data from 88 senior students were analysed: 47 students in the smartphone application group (experimental) and 41 in the educational booklet group (control). The procedures consisted of a face-to-face lecture plus self-study and a period of self-study only. Participants were tested at three time points: pre-test, post-test 1 (immediately after the programme’s completion) and post-test 2 (5 weeks after the programme’s completion). Results: Significant group differences were found at different times in STI knowledge, vulnerability, prevention self-efficacy and prevention intentions. Smartphone applications were more effective in sustaining the effects of the educational programme than the educational booklets. Conclusion: Researchers and educators should examine the role of relevant learning materials in the promotion of adolescents’ development of self-study skills and their knowledge acquisition.

An adequate number of high-quality nurses are a key factor for superior patient outcomes. However, in 2015, Cambodia reported only 52 nurses with bachelor's degrees, three with master's degrees, and one with a doctorate. The fast track to getting a highly educated nursing workforce requires providing a bridging program for associate's degree nurses to achieve baccalaureate degrees.To assess improvement in the competency of nursing students and faculty members through a program that prepares associate's degree nurses to obtain bachelor's degrees in Cambodia.Mixed methods.Educational institutes in Phnom Penh, Cambodia.A total of 45 Cambodian nursing students participated in the Cambodian nurse-bridging program and 12 Cambodian faculty members served as co-teachers.We conducted three surveys to compare the competence of nursing students and faculty members before, during, and after the bridging program. We conducted focus-group interviews to support the qualitative results and explored changes in student and faculty competencies after the program.Quantitative analysis revealed significant improvements in students' nursing competency (p .001), critical thinking (p .001), and research competency (p .001) and faculty members' teaching competency (p .001) and research competency (p .001) after the program. Through qualitative analysis, students showed improvement in physical assessment, patient communication, critical thinking, evidence-based nursing, and research competency. Faculty members indicated they had experienced new teaching strategies and subjects, gained increased confidence in teaching, and even though research competency had been improved, more training was required.This study provides evidence to support the effectiveness of higher nurse education in developing countries, and illustrates an opportunity to produce high-quality human resources in nursing.

Global health competency is an essential capacity for nursing students. This study evaluated the effect of a global outreach program on global health competency and cultural self-efficacy in nursing students and examined the students' experiences with the program. Participants included thirty-one undergraduate nursing students at a university in Seoul, Republic of Korea, who participated in a global outreach program in 2015 and 2016. Quantitative data were collected before and after program participation using questionnaires evaluating global health competency and cultural self-efficacy, and were analyzed using descriptive statistics and paired t-tests. Both global health competency and cultural self-efficacy increased significantly after the global outreach program. Qualitative data were collected via focus group interviews and reflective journals, and were analyzed using conventional content analysis and thematic analysis, respectively. The results of the content and thematic analyses were compared, and two themes and eight-sub-themes were finally extracted through the data analysis. The program was effective in improving nursing students' global health competency and cultural self-efficacy.

With the ever-increasing demands for higher energy densities in Li-ion batteries, alternative anodes with higher reversible capacity are required to replace the conventional graphite anode. Here, we demonstrate a cost-effective hydrothermal carbonization approach to prepare a hard carbon coated nano-Si/graphite (HC-nSi/G) composite as a high performance anode for Li-ion batteries. In this hierarchical structured composite, the hard carbon coating not only provides an efficient pathway for electron transfer, but also alleviates the volume variation of Si during charge/discharge processes. The HC-nSi/G composite electrode shows excellent performance, including a high specific capacity of 878.6 mAh g−1 based on the total weight of composite, good rate performance, and a decent cycling stability, which is promising for practical applications.

Developing green energy solutions has become crucial to society. However, to develop a clean and renewable energy system, significant developments must be made, not only in energy conversion technologies (such as solar panels and wind turbines) but also regarding the feasibility and capabilities of stationary electrical energy storage (EES) systems. Many types of EES systems have been considered such as pumped hydroelectric storage (PHS), compressed air energy storage (CAES), flywheels, and electrochemical storage. Among them, electrochemical storage such as battery has the advantage of being more efficient compared to other candidates, because it is more suitable in terms of the scalability, efficiency, lifetime, discharge time, and weight and/or mobility of the system. Currently, rechargeable lithium ion batteries (LIBs) are the most successful portable electricity storage devices, but their use is limited to small electronic equipment. Using LIBs to store large amounts of electrical energy in stationary applications is limited, not only by performance but also by cost. Thus, a viable battery technology that can store large amounts of electrical energy in stationary applications is needed. In this review, well-developed and recent progress on the chemistry and design of batteries, as well as their effects on the electrochemical performance, is summarized and compared. In addition, the challenges that are yet to be solved and the possibilities for further improvements are explored.

Aim This study explored health beliefs and behaviours related to sexually transmitted infections (STIs) from the perspective of juvenile offenders with STIs in three urban cities. Methods Data were collected using observations and in-depth interviews between July and November, 2014. Under the supervision of probation officers, 24 juvenile offenders with STIs were interviewed. Leininger's four-step method guided the data analysis. Findings From participants' perspectives, poor hygiene and a promiscuous lifestyle caused the STIs. The diseases were considered an adult disease with distinct symptoms and deformities, no cure, and therefore fatal. STIs were shameful for juveniles because their presence revealed sexually active behaviours. The juveniles' health-related behaviours included neglecting their STI symptoms because they did not know they were infected, mistaking STIs for other health conditions, choosing to suffer rather than revealing their diagnosis, and keeping their genitals clean. Conclusion A large gap emerged between juveniles' beliefs and behaviours related to STIs. Policies and education are needed to provide accurate STI information for this population.

Although various Si-based graphene nanocomposites provide enhanced electrochemical performance, these candidates still yield low initial coloumbic efficiency, electrical disconnection, and fracture due to huge volume changes after extended cycles lead to severe capacity fading and increase in internal impedance. Therefore, an innovative structure to solve these problems is needed. In this study, an amorphous (a) silicon nanoparticle backboned graphene nanocomposite (a-SBG) for high-power lithium ion battery anodes was prepared. The a-SBG provides ideal electrode structures-a uniform distribution of amorphous silicon nanoparticle islands (particle size10 nm) on both sides of graphene sheets-which address the improved kinetics and cycling stability issues of the silicon anodes. a-Si in the composite shows elastic behavior during lithium alloying and dealloying: the pristine particle size is restored after cycling, and the electrode thickness decreases during the cycles as a result of self-compacting. This noble architecture facilitates superior electrochemical performance in Li ion cells, with a specific energy of 468 W h kg(-1) and 288 W h kg(-1) under a specific power of 7 kW kg(-1) and 11 kW kg(-1), respectively.

A graphene-attached VS4 composite prepared by a simple hydrothermal method is studied in terms of its lithium reaction mechanism and high rate capability. The nanocomposite exhibits a good cycling stability and an impressive high-rate capability for lithium storage, delivering a comparable capacity of 630 and 314 mA h g−1, even at high rates of 10 and 20 C (=10 and 20 A g−1, or 10 and 20 mA cm−2), respectively. In addition, full-cell (LiMn2O4/VS4–graphene) test results also exhibited a good capacity retention. The mechanism of Li storage is systematically studied and a conversion reaction with an irreversible phase change during the initial discharge–charge process is proposed.

Mobile electronics have developed so rapidly that battery technology has hardly been able to keep pace. The increasing desire for lighter and thinner Li-ion batteries with higher capacities is a continuing and constant goal for in research. Achieving higher energy densities, which is mainly dependent on cathode materials, has become a critical issue in the development of new Li-ion batteries. In this review, we will outline the progress on nanostructured 4 V cathode materials of Li-ion batteries for mobile electronics, covering LiCoO 2 , LiNi x Co y Mn 1− x − y O 2 , LiMn 2 O 4 , LiNi 0.5 Mn 1.5 O 4 and Li-rich layered oxide materials. We aim to provide some scientific insights into the development of superior cathode materials by discussing the advantages of nanostructure, surface-coating, and other key properties.

Spindle-like porous α-Fe(2)O(3) was prepared from an iron-based metal organic framework (MOF) template. When tested as anode material for lithium batteries (LBs), this spindle-like porous α-Fe(2)O(3) shows greatly enhanced performance of Li storage. The particle with a length and width of ∼0.8 and ∼0.4 μm, respectively, was composed of clustered Fe(2)O(3) nanoparticles with sizes of

Oxidative stress is implicated in the pathogenesis of allergic asthma and remains an attractive target for the prevention of the disease. Herein, we investigated the anti-inflammatory effects of apocynin, a NADPH oxidase (NOX) inhibitor, in both in vitro and in vivo allergen-induced experimental asthma mediated by Th2 hyperresponsiveness. Apocynin showed potential antioxidant activities and inhibitory effects on the activation of redox-sensitive transcription factors, such as NF-κB and AP-1, induced by pro-inflammatory stimuli, such as TNF-α, lipopolysaccharide and Poly I:C, and that inhibited the production of pro-inflammatory cytokines, such as TNF-α, IL-1β and IL-6. In in vivo experimental asthma model, moreover, apocynin significantly attenuated ovalbumin-induced airway hyperresponsiveness and inflammation, as shown by the attenuation of total inflammatory cell and soluble product influx into bronchoalveolar lavage fluid, such as macrophages, eosinophils, IL-4, IL-5, IL-12, IL-13 and TNF-α. Apocynin also significantly reduced lung inflammation in the tissues. Altogether, these results suggest that apocynin may be useful in the treatment of inflammatory diseases induced by oxidative stress through NOX activity.

the presence of high-spin Mn 3 + :t2g 3 eg 1 ions—resulting in a huge change of volume and severe fading of the capacity. [7] The power density (rate capability) of these cathode materials with bulk sizes in the micrometer-regime is generally low due to the high level of polarization at high charge–discharge rates (above 2 C). This high polarization is believed to result from slow lithium diffusion or low electrical conductivity in the active material. Therefore, “nanostructuring” was introduced to overcome these shortcomings, through shortening the diffusion paths for mass transport and increasing the surface area for charge transfer. [8–10] In addition, electrode density is considered to be one of the factors that affects the energy density: a higher electrode density leads to a higher energy density. [11] A

Hydrothermally prepared 100 nm-sized LiCoO2 with a plate morphology packed in a crucible resulted in 40 μm-sized particles that consisted of aggregated

We present an amorphous Si anode deposited on a Cu nanopillar current collector, fabricated using a thermal roll-to-roll process followed by electroformation and LPCVD, for application in high-rate Li-ion batteries. Cu nanopillar current collectors with diameters of 250 and 500 nm were patterned periodically with 1 μm pitch and 2 μm height to optimize the diameters of the pillars for better electrochemical performance. Void spaces between Cu nanopillars allowed not only greater effective control of the strain caused by the Si expansion during lithiation than that allowed by a nonpatterned electrode but also significantly improved cycle performance even at 20 C measured after the same rate test: After 100 cycles at 0.5 C, the patterned electrodes with 250 and 500 nm diameter nanopillars showed high capacity retentions of 86% and 84%, respectively. These electrodes retained discharge capacities of 1057 and 780 mAh/g even at 20 C, respectively.

Salt-inducible kinases (SIKs) are a family of related serine-threonine kinases and are involved in controlling various metabolisms such as liver glucose homeostasis, hepatic lipogenesis, steroidogenesis, and adipogenesis. Here we investigated the regulatory role of SIK proteins in Toll-like receptor 4 (TLR4)-mediated signaling. Overexpression of SIK1 and SIK3, but not SIK2, significantly inhibited nuclear factor-κB activity in response to lipopolysaccharide stimulation and affected the expression of proinflammatory cytokines. In contrast, both SIK1(KD) and SIK3(KD) Raw 264.7 cells exhibit dramatic elevations of nuclear factor-κB activation and activations of downstream signaling molecules, such as TGF-β-activated kinase 1, p38, and c-Jun N-terminal kinase, in response to TLR4 stimulation, indicating that SIK1 and SIK3 are negatively involved in the TLR4-mediated signaling. Through biochemical studies, we found that SIK1 and SIK3 interact with TGF-β-activated kinase 1-binding protein 2 (TAB2), and interrupt the functional complex of TAB2-TNF receptor-associated factor 6 (TRAF6). Interestingly, the molecular interruption is induced to suppress the ubiquitination of TRAF6 in response to TLR4 stimulation. These result suggest that SIK1 and SIK3 negatively regulate TLR4-mediated signaling through the interruption of TAB2-TRAF6 complex and thereby the inhibition of ubiquitination of TRAF6. The present findings can be useful for a better understanding of multilevel interactions between the metabolic and immune systems.

Carbon and carbon-based composite materials have long been an important component in electrodes utilized for energy storage applications. Their widespread use can be attributed to their combination of good electrical conductivity, relative chemical inertness and low bulk material density (~2 g/cm3). For lithium ion battery (LIB) anodes, graphite is typically employed, but silicon has been heralded an excellent replacement candidate due to its very high theoretical capacity (~ 4200 mAh/g—a capacity over ten times greater than that of graphite). A principal obstacle for the practical application of a Si anode is the extreme volume changes (> 300%) during the lithiation process which eventually leads to a pulverization of the Si material. This is particularly true for larger Si particles (> 200 nm), which severely compromises the commercialization of Si based LIB anodes. Herein, we present our recent work utilizing various carbon-silicon composite materials systems as LIB anodes. We will show that by using a hierarchical porous carbon scaffold with tailorable textural properties such as pore size, surface area and pore volume, we are able to provide silicon nanoparticles with an excellent scaffold for attachment. Furthermore, we will reveal how this tailorable carbon structure can be further modified via functionalization pathways for both the carbon and silicon materials. We will demonstrate how these strategies improved various performance parameters for these LIB anodes; specifically in terms of cyclic performance—a characteristic weak point for silicon-based LIB anodes.

With the ever increasing demands on Li-ion batteries with higher energy densities, alternative anode with higher reversible capacity is required to replace the conventional graphite anode. Here, we demonstrate a cost-effective hydrothermal-carbonization approach to prepare the hard carbon coated nano-Si/graphite (HC-nSi/G) composite as a high performance anode for Li-ion batteries. In this hierarchical structured composite, the hard carbon coating layer not only provides an efficient pathway for electron transfer, but also alleviates the volume variation of silicon during charge/discharge processes. The HC-nSi/G composite electrode shows excellent electrochemical performances including a high specific capacity of 878.6 mAh g-1 based on the total weight of composite, good rate performance (398 mAh g-1 at 4C (2.4 mA g-1)) and a decent cycling stability (75.2% capacity retention over 150 cycles at 1.5 mAh cm-2 areal capacity loading), which is promising for practical applications.

Carbon and carbon-based composite materials are an important component in electrodes utilized for energy storage applications. Their widespread use can be attributed to carbon’s combination of good electrical conductivity, relative chemical inertness and low bulk material density (~2 g/cm3). For lithium ion battery (LIB) anodes, graphite is typically employed, but silicon has been heralded an excellent replacement candidate due to its very high theoretical capacity (~ 4200 mAh/g—a capacity over ten times greater than that of graphite). A principal obstacle for the practical application of a Si anode is the extreme volume changes (> 300%) during the lithiation process which eventually leads to a pulverization of the Si material. This is particularly true for larger Si particles (> 200 nm), which severely compromises the commercialization of Si based LIB anodes. Herein, we present our recent work utilizing hierarchical porous carbon as a host for silicon to be used as an anode for LIB anodes. We will show that by using a porous carbon scaffold with tailorable textural properties such as pore size, surface area and pore volume, we are able to provide silicon nanoparticles with an excellent scaffold for attachment. Furthermore, we will reveal how this tailorable carbon structure can be further modified via functionalization pathways for both the carbon and silicon materials. We will demonstrate how these strategies improved various performance parameters for these LIB anodes; specifically in terms of cyclic performance—a characteristic weak point for silicon-based LIB anodes.

Spindle-like porous α-Fe(2)O(3) was prepared from an iron-based metal organic framework (MOF) template. When tested as anode material for lithium batteries (LBs), this spindle-like porous α-Fe(2)O(3) shows greatly enhanced performance of Li storage. The particle with a length and width of ∼0.8 and ∼0.4 μm, respectively, was composed of clustered Fe(2)O(3) nanoparticles with sizes of20 nm. The capacity of the porous α-Fe(2)O(3) retained 911 mAh g(-1) after 50 cycles at a rate of 0.2 C. Even when cycled at 10 C, comparable capacity of 424 mAh g(-1) could be achieved.

Motivated by new applications including electric vehicles and the smart grid, interest in advanced lithium ion batteries has increased significantly over the past decade. Therefore, research in this field has intensified to produce safer devices with better electrochemical performance. Most research has focused on the development of new electrode materials through the optimization of bulk properties such as crystal structure, ionic diffusivity, and electric conductivity. More recently, researchers have also considered the surface properties of electrodes as critical factors for optimizing performance. In particular, the electrolyte decomposition at the electrode surface relates to both a lithium ion battery's electrochemical performance and safety. In this Account, we give an overview of the major developments in the area of surface chemistry for lithium ion batteries. These ideas will provide the basis for the design of advanced electrode materials. Initially, we present a brief background to lithium ion batteries such as major chemical components and reactions that occur in lithium ion batteries. Then, we highlight the role of surface chemistry in the safety of lithium ion batteries. We examine the thermal stability of cathode materials: For example, we discuss the oxygen generation from cathode materials and describe how cells can swell and heat up in response to specific conditions. We also demonstrate how coating the surfaces of electrodes can improve safety. The surface chemistry can also affect the electrochemistry of lithium ion batteries. The surface coating strategy improved the energy density and cycle performance for layered LiCoO2, xLi2MnO3·(1 - x)LiMO2 (M = Mn, Ni, Co, and their combinations), and LiMn2O4 spinel materials, and we describe a working mechanism for these enhancements. Although coating the surfaces of cathodes with inorganic materials such as metal oxides and phosphates improves the electrochemical performance and safety properties of batteries, the microstructure of the coating layers and the mechanism of action are not fully understood. Therefore, researchers will need to further investigate the surface coating strategy during the development of new lithium ion batteries.

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