Si Nanowires: From Model System to Practical Li-Ion Anode Material and Beyond.

Nanowire (NW)-based anodes for Li-ion batteries (LIBs) have been under investigation for more than a decade, with their unique one-dimensional (1D) morphologies and ability to transform into interconnected active material networks offering potential for enhanced cycling stability with high capacity. This is particularly true for silicon (Si)-based anodes, where issues related to large volumetric expansion can be partially mitigated and the cycle life can be enhanced. In this Perspective, we highlight the trajectory of Si NWs from a model system to practical Li-ion battery anode material and future prospects for extension to beyond Li-ion batteries. The study examines key research areas related to Si NW-based anodes, including state-of-the-art (SoA) characterization approaches followed by practical anode design considerations, including NW composite anode formation and upscaling/full-cell considerations. An outlook on the practical prospects of NW-based anodes and some future directions for study are detailed.

Revealing Seed-Mediated Structural Evolution of Copper-Silicide Nanostructures: Generating Structured Current Collectors for Rechargeable Batteries.

Metal silicide thin films and nanostructures typically employed in electronics have recently gained significant attention in battery technology, where they are used as active or inactive materials. However, unlike thin films, the science behind the evolution of silicide nanostructures, especially 1D nanowires (NWs), is a key missing aspect. CuxSiy nanostructures synthesized by solvent vapor growth technique are studied as a model system to gain insights into metal silicide formation. The temperature-dependent phase evolution of CuxSiy structures proceeds from Cu>Cu0.83Si0.17>Cu5Si>Cu15Si4. The role of Cu diffusion kinetics on the morphological progression of Cu silicides is studied, revealing that the growth of 1D metal silicide NWs proceeds through an in situ formed, Cu seed-mediated, self-catalytic process. The different CuxSiy morphologies synthesized are utilized as structured current collectors for K-ion battery anodes. Sb deposited by thermal evaporation upon Cu15Si4 tripod NWs and cube architectures exhibit reversible alloying capacities of 477.3 and 477.6 mAh g-1 at a C/5 rate. Furthermore, Sb deposited Cu15Si4 tripod NWs anode tested in Li-ion and Na-ion batteries demonstrate reversible capacities of ≈518 and 495 mAh g-1.

Dual-chamber versus single chamber pacemakers, a systemic review and meta-analysis on sick sinus syndrome and atrioventricular block patients.

Aims: The atrioventricular block (AVB) is a conduction system problem that results from the impairment in the transmission of an impulse from the atria to the ventricle, the disease has many etiologies. This article aimed to evaluate the efficacy and safety of dual and single-chamber pacemakers in patients with SSS and AVB. Methods: An electronic search of PubMed (Medline), EMBASE, and Google Scholar was performed from 2000 till August 15th, 2022. Retrieved articles were exported to Endnote Reference Library Software, where duplicate studies were removed from the list, and only articles meeting the eligibility criteria of this study were selected. RevMan 5.4 and STATA 16 software were used for the analysis. The modified Cochrane Collaboration's risk of bias and New-castle Ottawa scale were used for quality assessment of RCTs and observational studies respectively. Results: This study is composed of 8953 patients with sick-sinus syndrome and atrioventricular block. A total of thirteen outcomes are included in this meta-analysis, out of which atrial fibrillation significantly favored dual chamber [OR = 1.29; 95 % CI = 1.05-1.59; P = 0.01 I2 = 29 %] and overall complications [OR = 0.48; 95 % CI = 0.29-0.77; p = 0.03 I2 = 0 %] and pneumothorax [OR = 0.31; 95 % CI = 0.10-0.93; p = 0.04, I2 = 0 %] were satisfied by single-chamber pacing. Conclusion: This study concluded that neither single-chamber nor dual-chamber pacemakers are superior to each other, but they are unique in their own ways as the results of this study manifest remarkable reduction in atrial fibrillation rates and pneumothorax using dual-chamber and single-chamber pacemakers respectively.

Colloidal synthesis of the mixed ionic-electronic conducting NaSbS2 nanocrystals.

Solution-based synthesis of mixed ionic and electronic conductors (MIECs) has enabled the development of novel inorganic materials with implications for a wide range of energy storage applications. However, many technologically relevant MIECs contain toxic elements (Pb) or are prepared by using traditional high-temperature solid-state synthesis. Here, we provide a simple, low-temperature and size-tunable (50-90 nm) colloidal hot injection approach for the synthesis of NaSbS2 based MIECs using widely available and non-toxic precursors. Key synthetic parameters (cationic precursor, reaction temperature, and ligand) are examined to regulate the shape and size of the NaSbS2 nanocrystals (NCs). FTIR studies revealed that ligands with carboxylate functionality are coordinated to the surface of the synthesized NaSbS2 NCs. The synthesized NaSbS2 nanocrystals have electronic and ionic conductivities of 3.31 × 10-10 (e-) and 1.9 × 10-5 (Na+) S cm-1 respectively, which are competitive with the ionic and electrical conductivities of perovskite materials generated by solid-state reactions. This research gives a mechanistic understanding and post-synthetic evaluation of parameters influencing the formation of sodium antimony chalcogenides materials.

Usefulness of electrocardiography QT interval for prediction of left ventricular diastolic dysfunction: a cross-sectional study.

Heart failure (HF) is a leading cause of morbidity and mortality worldwide, with projections showing a further rise in incidence, impacting a decline in quality of life and the costs incurred in its diagnosis and treatment. The authors aim to establish the correlation between the prediction of left ventricular diastolic dysfunction based on a change in QT wave intervals. Methods: A cross-sectional at Holy-family Hospital, Rawalpindi Medical University, Pakistan. One thousand five hundred patients were referred for electrocardiography (ECG) for clinical suspicion of HF between May and July 2022. Ejection fraction (EF), lateral mitral annulus velocity (e'), mitral inflow early (E) and late (A) velocities, left ventricular filling pressure (E/e' ratio), and QT interval (QTc) was calculated. Odds ratios with a 95% CI (odds) were obtained by comparing QTc with all variables. Results: The patients were mostly middle-aged adults with a mean age of 30.27 (±7.64). Male to female ratio was nearly balanced, with 771 (51.4%) males included in the clinical survey. The ECG parameters were; QT interval-494.07 (±63.61), EF-57.11 (±11.96), early to atrial filling velocity ratio-0.71 (±0.20), and lateral mitral annulus velocity-8.29 (±1.64). Conclusion: The promising results for correlation between QT interval and ECG parameters, particularly EF and lateral mitral annulus velocity, should not be considered as the alternative in diagnosing left ventricular diastolic dysfunction thus far. Prolonged electrocardiographic QTc interval in patients with HF is useful in predicting diastolic dysfunction.

Temperature induced diameter variation of silicon nanowires via a liquid-solid phase transition in the Zn seed.

Herein, we demonstrate the ability of Zn to catalyze the growth of Si nanowires via reaction temperature determined, vapour-liquid-solid (VLS) or vapour-solid-solid (VSS) growth mechanisms. This is the first reported use of a type B catalyst to grow Si nanowires via the VSS mechanism to our knowledge whereby the highly faceted Zn seeds resulted in an increased NW diameter. This was used to induce diameter variations along the axial length of individual nanowires by transitioning between VLS and VSS growth.

Realizing High-Performance Li-Polysulfide Full Cells by using a Lithium Bis(trifluoromethanesulfonyl)imide Salt Electrolyte for Stable Cyclability.

Since concentrated electrolytes have attracted great attention for the stabilization of lithium-metal anodes for lithium-ion batteries, the demonstration of a full cell with an electrolyte concentration study has become a research topic of interest. Herein, we have demonstrated a proof of concept, a lithium-polysulfide full cell battery using various lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) electrolyte concentrations with glass-fiber-based composite and hard carbon as the cathode and anode, respectively. The initial capacity of the lithium-polysulfide full cell is found to be 970 mA h g-1 at 0.1 C. The capacity is stabilized at 870 mA h g-1 after 100 cycles with a capacity retention of 88.6 %. An excellent capacity retention of ≈80 % is achieved after long 800 cycles at 0.5 C by using full cell technology. Further, our post-mortem analysis sheds light on the difference in SEI layer formation on hard carbon anodes with changing electrolyte concentration, thereby indicating reasons for the obtainment of a high cyclic performance with 1 m LiTFSI salt electrolyte. The successful demonstration of the long cyclic performance of Li-polysulfide full cells is indeed a step towards producing high performance Li-polysulfide full cell batteries with long cycling using conventional LiTFSI salt electrolyte and commercial anode materials.

Unveiling the synergistic effect of polysulfide additive and MnO2 hollow spheres in evolving a stable cyclic performance in Li-S batteries.

Herein, we demonstrate a synergistic approach involving polar-based oxide and polysulfide additives for effectively suppressing polysulfide dissolution during cycling. The MnO2 hollow spheres not only provide physical confinement for the polysulfide species but also enable strong chemical interactions between polysulfide species and oxides, while the added polysulfide furnishes a mass buffering effect and compensates for the capacity losses due to partial cathode dissolution during discharge. The capacity retentions of S/KB, S/KB/LiPS, S/KB/MnO2, and S/KB/MnO2/LiPS composite cathodes are 31%, 45%, 59%, and 91% respectively. The remarkable capacity retention of the S/KB/LiPS/MnO2 composite electrode is mainly attributed to the synergistic effect between MnO2 and polysulfide additives.