25 research outputs found

    Impact of CO2 activation on the structure, composition, and performance of Sb/C nanohybrid lithium/sodium-ion battery anodes

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    Antimony (Sb) has been regarded as one of the most promising anode materials for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) and attracted much attention in recent years. Alleviating the volumetric effect of Sb during charge and discharge processes is the key point to promote Sb-based anodes to practical applications. Carbon dioxide (CO2) activation is applied to improve the rate performance of the Sb/C nanohybrid anodes caused by the limited diffusion of Li/Na ions in excessive carbon components. Based on the reaction between CO2 and carbon, CO2 activation can not only reduce the excess carbon content of the Sb/C nanohybrid but also create abundant mesopores inside the carbon matrix, leading to enhanced rate performance. Additionally, CO2 activation is also a fast and facile method, which is perfectly suitable for the fabrication system we proposed. As a result, after CO2 activation, the average capacity of the Sb/C nanohybrid LIB anode is increased by about 18 times (from 9 mA h g−1 to 160 mA h g−1) at a current density of 3300 mA g−1. Moreover, the application of the CO2-activated Sb/C nanohybrid as a SIB anode is also demonstrated, showing good electrochemical performance

    Carbon-emcoating architecture boosts lithium storage of Nb2O5

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    Intercalation transition metal oxides (ITMO) have attracted great attention as lithium-ion battery negative electrodes due to high operation safety, high capacity and rapid ion intercalation. However, the intrinsic low electron conductivity plagues the lifetime and cell performance of the ITMO negative electrode. Here we design a new carbon-emcoating architecture through single CO2 activation treatment as demonstrated by the Nb2O5/C nanohybrid. Triple structure engineering of the carbon-emcoating Nb2O5/C nanohybrid is achieved in terms of porosity, composition, and crystallographic phase. The carbon-embedding Nb2O5/C nanohybrids show superior cycling and rate performance compared with the conventional carbon coating, with reversible capacity of 387 mA h g−1 at 0.2 C and 92% of capacity retained after 500 cycles at 1 C. Differential electrochemical mass spectrometry (DEMS) indicates that the carbon emcoated Nb2O5 nanohybrids present less gas evolution than commercial lithium titanate oxide during cycling. The unique carbon-emcoating technique can be universally applied to other ITMO negative electrodes to achieve high electrochemical performance

    Dental resin monomer enables unique NbO2/carbon lithium‐ion battery negative electrode with exceptional performance

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    Niobium dioxide (NbO2) features a high theoretical capacity and an outstanding electron conductivity, which makes it a promising alternative to the commercial graphite negative electrode. However, studies on NbO2 based lithium-ion battery negative electrodes have been rarely reported. In the present work, NbO2 nanoparticles homogeneously embedded in a carbon matrix are synthesized through calcination using a dental resin monomer (bisphenol A glycidyl dimethacrylate, Bis-GMA) as the solvent and a carbon source and niobium ethoxide (NbETO) as the precursor. It is revealed that a low Bis-GMA/NbETO mass ratio (from 1:1 to 1:2) enables the conversion of Nb (V) to Nb (IV) due to increased porosity induced by an alcoholysis reaction between the NbETO and Bis-GMA. The as-prepared NbO2/carbon nanohybrid delivers a reversible capacity of 225 mAh g−1 after 500 cycles at a 1 C rate with a Coulombic efficiency of more than 99.4% in the cycles. Various experimental and theoretical approaches including solid state nuclear magnetic resonance, ex situ X-ray diffraction, differential electrochemical mass spectrometry, and density functional theory are utilized to understand the fundamental lithiation/delithiation mechanisms of the NbO2/carbon nanohybrid. The results suggest that the NbO2/carbon nanohybrid bearing high capacity, long cycle life, and low gas evolution is promising for lithium storage applications

    The anatomy of reliability: a must read for future human brain mapping

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    Human brain mapping (HBM) is increasingly becoming a multi-disciplinary field where some scientific issues are fundamental for all scientists and applications of using the technology to investigate individual differences. Reliability represents a significant issue for all scientific fields and has particularly been overlooked for decades by the HBM field 1. Meanwhile, recent advances in open science have offered the field big data for developing novel methodological frameworks as well as performing large-scale investigations of the brain-mind associations based upon the individual differences assessed with HBM 2. A systematic investigation of reliability seems still far behind these HBM developments. It is critical that reliability is evaluated ahead of these applications, motivating the current commentary on delineation of the anatomy of reliability for future HBM

    Silicon based lithium-ion battery anodes: A chronicle perspective review

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    Si has been regarded as one of the most promising next generation lithium-ion battery (LIB) anodes due to its exceptional capacity and proper working voltage. However, the dramatic volume change during lithiation/delithiation processes has caused severe detrimental consequences, leading to very poor cyclic stability. It has been one of the critical problems hampering the practical applications of the silicon based LIB anode. Extensive research has been carried out to resolve the problem since early 1990s. For the first time, the studies on the Si anode in the time frame more than two decades are summarized and discussed in this review with a novel chronicle perspective. Through this article, the evolution of the concept, fundamental scientific and technology development of the silicon LIB anode are clearly presented. It provides unique eyesight into this rapid developing field and will shed light on the future trend of the Si LIB anode research

    Association of Gut Microbiota Enterotypes with Blood Trace Elements in Women with Infertility

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    Infertility is defined as failure to achieve pregnancy within 12 months of unprotected intercourse in women. Trace elements, a kind of micronutrient that is very important to female reproductive function, are affected by intestinal absorption, which is regulated by gut microbiota. Enterotype is the classification of an intestinal microbiome based on its characteristics. Whether or not Prevotella-enterotype and Bacteroides-enterotype are associated with blood trace elements among infertile women remains unclear. The study aimed to explore the relationship between five main whole blood trace elements and these two enterotypes in women with infertility. This retrospective cross-sectional study recruited 651 Chinese women. Whole blood copper, zinc, calcium, magnesium, and iron levels were measured. Quantitative real-time PCR was performed on all fecal samples. Patients were categorized according to whole blood trace elements (low levels group, <5th percentile; normal levels group, 5th‒95th percentile; high levels group, >95th percentile). There were no significant differences in trace elements between the two enterotypes within the control population, while in infertile participants, copper (P = 0.033), zinc (P < 0.001), magnesium (P < 0.001), and iron (P < 0.001) in Prevotella-enterotype was significantly lower than in Bacteroides-enterotype. The Chi-square test showed that only the iron group had a significant difference in the two enterotypes (P = 0.001). Among infertile patients, Prevotella-enterotype (Log(P/B) > −0.27) predicted the low levels of whole blood iron in the obesity population (AUC = 0.894; P = 0.042). For the high levels of iron, Bacteroides-enterotype (Log(P/B) <−2.76) had a predictive power in the lean/normal group (AUC = 0.648; P = 0.041) and Log(P/B) <−3.99 in the overweight group (AUC = 0.863; P = 0.013). We can infer that these two enterotypes may have an effect on the iron metabolism in patients with infertility, highlighting the importance of further research into the interaction between enterotypes and trace elements in reproductive function

    The Advantage of Growth Hormone Alone as an Adjuvant Therapy in Advanced Age and BMI ≥ 24 kg/m2 with In Vitro Fertilization Failure Due to Poor Embryo Quality

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    This study aimed to assess the effects of GH adjuvant therapy on the cumulative live birth rate in patients with poor embryo quality and to determine the characteristics of patients who are more responsive to GH. A retrospective cohort study was carried out in patients who have suffered from previous IVF failure due to poor embryonic development and underwent IVF with or without a 6-week pretreatment with GH in the subsequent cycle from January 2018 to December 2020. Clinical parameters including the cumulative live birth rate between the (−) GH and (+) GH groups were compared. Multivariate analysis was performed to ascertain associations between clinical parameters and cumulative live birth rate. Upon analysis of the clinical data from 236 IVF cycles, 84 patients received GH and 152 did not receive GH. In frozen embryo transfer cycles, compared with the (−) GH group, the implantation rate and live birth rate were significantly higher in the (+) GH group (p < 0.05). After adjusting for possible confounding factors, GH improved cumulative live birth per oocyte retrieval cycle by 1.96 folds (p = 0.032). Furthermore, when patients were subdivided based on age and BMI, a significant increase in the cumulative live birth rate was found in the (+) GH group of patients between 35 and 42 years old and BMI ≥ 24 kg/m2, respectively (p < 0.05). GH may increase the live birth rate in women who experienced IVF failure because of poor embryonic development, particularly in obese patients and women with advanced age

    Poly(siloxane imide) Binder for Silicon-Based Lithium-Ion Battery Anodes via Rigidness/Softness Coupling

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    Binders play a crucial role in maintaining mechanical integrity of electrodes in lithium-ion batteries. However, the conventional binders lack proper elasticity, and they are not suitable for high-performance silicon anodes featuring huge volume change during cycling. Herein, a poly(siloxane imide) copolymer (PSI) has been designed, synthesized, and utilized as a binder for silicon-based anodes. A rigidness/softness coupling mechanism is demonstrated by the PSI binder, which can accommodate volume expansion of the silicon anode upon lithiation. The electrochemical performance in terms of cyclic stability and rate capability can be effectively improved with the PSI binder as demonstrated by a silicon nanoparticle anode
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