3D Hierarchical Sunflower-Shaped MoS2/SnO2 Photocathodes for Photo-Rechargeable Zinc Ion Batteries.

Photo-rechargeable zinc-ion batteries (PRZIBs) have attracted much attention in the field of energy storage due to their high safety and dexterity compared with currently integrated lithium-ion batteries and solar cells. However, challenges remain toward their practical applications, originating from the unsatisfactory structural design of photocathodes, which results in low photoelectric conversion efficiency (PCE). Herein, a flexible MoS2/SnO2-based photocathode is developed via constructing a sunflower-shaped light-trapping nanostructure with 3D hierarchical and self-supporting properties, enabled by the hierarchical embellishment of MoS2 nanosheets and SnO2 quantum dots on carbon cloth (MoS2/SnO2 QDs@CC). This structural design provides a favorable pathway for the effective separation of photogenerated electron-hole pairs and the efficient storage of Zn2+ on photocathodes. Consequently, the PRZIB assembled with MoS2/SnO2 QDs@CC delivers a desirable capacity of 366 mAh g-1 under a light intensity of 100 mW cm-2, and achieves an ultra-high PCE of 2.7% at a current density of 0.125 mA cm-2. In practice, an integrated battery system consisting of four series-connected quasi-solid-state PRZIBs is successfully applied as a wearable wristband of smartwatches, which opens a new door for the application of PRZIBs in next-generation flexible energy storage devices.

A facile synthesis of FeS/Fe3C nanoparticles highly dispersed on in situ grown N-doped CNTs as cathode electrocatalysts for microbial fuel cells.

A novel composite of iron sulfide, iron carbide and nitrogen carbides (Nano-FeS/Fe3C@NCNTs) as a cathode electrocatalyst for microbial fuel cells (MFCs) is synthesized by a one-pot solid state reaction, which yields a unique configuration of FeS/Fe3C nanoparticles highly dispersed on in situ grown nitrogen-doped carbon nanotubes (NCNTs). The highly dispersed FeS/Fe3C nanoparticles possess large active sites, while the NCNTs provide an electronically conductive network. Consequently, the resultant Nano-FeS/Fe3C@NCNTs exhibit excellent electrocatalytic activity towards the oxygen reduction reaction (ORR), with a half-wave potential close to that of Pt/C (about 0.88 V vs. RHE), and enable MFCs to deliver a power density of 1.28 W m-2 after two weeks' operation, which is higher than that of MFCs with Pt/C as the cathode electrocatalyst (1.02 W m-2). Theoretical calculations and experimental data demonstrate that there is a synergistic effect between Fe3C and FeS in Nano-FeS/Fe3C@NCNTs. Fe3C presents a strong attraction and electron-donating tendency to oxygen molecules, serving as the main active component, while FeS reduces charge transfer resistance by transferring electrons to Fe3C, synergistically improving the kinetics of the ORR and power density of MFCs.

Insight into the Contribution of Nitriles as Electrolyte Additives to the Improved Performances of the LiCoO2 Cathode.

Nitriles have been successfully used as electrolyte additives for performance improvement of commercialized lithium-ion batteries based on the LiCoO2 cathode, but the underlying mechanism is unclear. In this work, we present an insight into the contribution of nitriles via experimental and theoretical investigations, taking for example succinonitrile. It is found that succinonitrile can be oxidized together with PF6- preferentially on LiCoO2 compared to the solvents in the electrolyte, making it possible to avoid the formation of hydrogen fluoride from the electrolyte oxidation decomposition, which is detrimental to the LiCoO2 cathode. Additionally, inorganic LiF and -NH group-containing polymers are formed from the preferential oxidation of succinonitrile, constructing a protective interphase on LiCoO2, which suppresses electrolyte oxidation decomposition and prevents LiCoO2 from structural deterioration. Consequently, the LiCoO2 cathode presents excellent stability under cycling and storing at high voltages.

Significance of serum fibroblast growth factor-23 and miR-208b in pathogenesis of atrial fibrillation and their relationship with prognosis.

BACKGROUND: The incidence and prevalence of atrial fibrillation are increasing each year, and this condition is one of the most common clinical arrhythmias. AIM: To investigate the levels and significance of serum fibroblast growth factor 23 (FGF-23) and miR-208b in patients with atrial fibrillation and their relationship with prognosis. METHODS: From May 2018 to October 2019, 240 patients with atrial fibrillation were selected as an observation group, including 134 with paroxysmal atrial fibrillation and 106 with persistent atrial fibrillation; 150 patients with healthy sinus rhythm were selected as a control group. The serum levels of FGF-23 and miR-208b in the two groups were measured. In the observation group, cardiac parameters were determined by echocardiography. RESULTS: The serum levels of FGF-23 and miR-208b in the observation group were 210.20 ± 89.60 ng/mL and 5.30 ± 1.22 ng/mL, which were significantly higher than the corresponding values in the control group (P < 0.05). In the observation group, the serum levels of FGF-23 and miR-208b in patients with persistent atrial fibrillation were 234.22 ± 70.05 ng/mL and 5.83 ± 1.00 ng/mL, which were significantly higher than the corresponding values in patients with paroxysmal atrial fibrillation (P < 0.05). The left atrial dimension (LAD) of patients with persistent atrial fibrillation was 38.81 ± 5.11 mm, which was significantly higher than that of patients with paroxysmal atrial fibrillation (P > 0.05). The serum levels of FGF-23 and miR-208b were positively correlated with the LAD (r = 0.411 and 0.382, P < 0.05). In the observation group, the serum levels of FGF-23 and miR-208b in patients with a major cardiovascular event (MACE) were 243.30 ± 72.29 ng/mL and 6.12 ± 1.12 ng/mL, which were significantly higher than the corresponding values in patients without a MACE (P < 0.05). CONCLUSION: The serum levels of FGF-23 and miR-208b are increased in patients with atrial fibrillation and are related to the type of disease, cardiac parameters, and prognosis.

Thermal pyrolysis of Si@ZIF-67 into Si@N-doped CNTs towards highly stable lithium storage.

Silicon is attracting considerable attention as an active anode material for advanced lithium-ion batteries due to its ultrahigh theoretical capacity. However, the reversible utilization of silicon-based anode materials is still hindered by the rapid capacity decay, as a consequence of the huge volume change of silicon during cycling. Herein, we use a Co-zeolitic imidazole framework (ZIF-67) to prepare silicon-wrapped nitrogen-doped carbon nanotubes (Si@N-doped CNTs) by controllable thermal pyrolysis. The as-prepared nanocomposites can effectively prevent pulverization and accommodate volume fluctuations of silicon during cycling. It can deliver a highly reversible capacity of 1100 mAh g-1 even after 750 cycles at a current density of 1000 mA g-1. As confirmed by an in situ transmission electron microscopy experiment, the remarkable electrochemical performance of Si@N-doped CNTs is attributed to the high electronic conductivity and flexibility of cross-linked N-doped CNTs network as a cushion to mitigate the mechanical stress and volume expansion. Furthermore, a full cell consisting of Si@N-doped CNTs anode and LiFePO4 cathode delivers a high reversible capacity of 1264 mAh g-1 and exhibits good cycling stability (>85% capacity retention) over 140 cycles at 1/4 C (1 C = 4000 mA g-1) rate.

A Heat-Resistant Poly(oxyphenylene benzimidazole)/Ethyl Cellulose Blended Polymer Membrane for Highly Safe Lithium-Ion Batteries.

A blended membrane based on poly(oxyphenylene benzimidazole) (PBI) and ethyl cellulose (EC) exhibits heat resistance and good electrochemical performance. The prepared blended polymer gel membranes show no visible dimensional change after being held at 350 °C for 30 min, whereas the polyethylene (PE) separator almost completely melts. In addition to excellent thermal stability, the self-supporting blended membranes also exhibit a uniform thermal distribution during the heating process from 60 to 200 °C. Additionally, the ionic conductivities of the PBI/EC blended membranes with different ratios are 1.24 mS cm-1 (1:1), 2.58 mS cm-1 (1:2), and 1.68 mS cm-1 (1:3), which are much higher than those of the PE separator (0.39 mS cm-1). Compared to that of the PE separator (113 mAh g-1), the cell with a separator of PBI/EC = 1:2 retained a discharge capacity of 131 mAh g-1 after 150 cycles at 0.5C. Meanwhile, the rate performance of the cell was also better than that of the PE separator, especially at high currents (5C). All of the results indicate that this blended polymer gel membrane with good thermal stability is expected to be applied to high-performance lithium-ion batteries.

Hierarchical Co3O4 Nano-Micro Arrays Featuring Superior Activity as Cathode in a Flexible and Rechargeable Zinc-Air Battery.

All-solid-state zinc-air batteries are characterized as low cost and have high energy density, providing wearable devices with an ideal power source. However, the sluggish oxygen reduction and evolution reactions in air cathodes are obstacles to its flexible and rechargeable application. Herein, a strategy called MOF-on-MOF (MOF, metal-organic framework) is presented for the structural design of air cathodes, which creatively develops an efficient oxygen catalyst comprising hierarchical Co3O4 nanoparticles anchored in nitrogen-doped carbon nano-micro arrays on flexible carbon cloth (Co3O4@N-CNMAs/CC). This hierarchical and free-standing structure design guarantees high catalyst loading on air cathodes with multiple electrocatalytic activity sites, undoubtedly boosting reaction kinetics, and energy density of an all-solid-state zinc-air battery. The integrated Co3O4@N-CNMAs/CC cathode in an all-solid-state zinc-air battery exhibits a high open circuit potential of 1.461 V, a high capacity of 815 mAh g-1 Zn at 1 mA cm-2, a high energy density of 1010 Wh kg-1 Zn, excellent cycling stability as well as outstanding mechanical flexibility, significantly outperforming the Pt/C-based cathode. This work opens a new door for the practical applications of rechargeable zinc-air batteries in wearable electronic devices.

Lithium Bis(oxalate)borate Reinforces the Interphase on Li-Metal Anodes.

Li metal provides an ideal anode for the highest energy density batteries, but its reactivity with electrolytes brings poor cycling stability. Electrolyte additives have been employed to effectively improve the cycling stability, often with the underlying mechanism poorly understood. In this work, applying lithium bis(oxalate)borate (LiBOB) as a chemical source for a dense and protective interphase, we investigate this issue with combined techniques of electrochemical/physical characterizations and theoretical calculations. It was revealed that the solid electrolyte interphase (SEI) formed by Li and the carbonate electrolyte is unstable and responsible for the fast deterioration of the Li anode. When LiBOB is present in the electrolyte, a reinforced SEI was formed, enabling significant improvement in cycling stability due to the preferential reduction of the BOB anion over the carbonate molecules and the strong combination of its reduction products with the species from the electrolyte reduction. The effectiveness of such new SEI chemistry on the Li anode supports excellent performance of a Li/LiFePO4 cell. This approach provides a pathway to rationally design an interphase on the Li anode so that high energy density batteries could be realized.

Bi Nanoparticles Anchored in N-Doped Porous Carbon as Anode of High Energy Density Lithium Ion Battery.

A novel bismuth-carbon composite, in which bismuth nanoparticles were anchored in a nitrogen-doped carbon matrix (Bi@NC), is proposed as anode for high volumetric energy density lithium ion batteries (LIBs). Bi@NC composite was synthesized via carbonization of Zn-containing zeolitic imidazolate (ZIF-8) and replacement of Zn with Bi, resulting in the N-doped carbon that was hierarchically porous and anchored with Bi nanoparticles. The matrix provides a highly electronic conductive network that facilitates the lithiation/delithiation of Bi. Additionally, it restrains aggregation of Bi nanoparticles and serves as a buffer layer to alleviate the mechanical strain of Bi nanoparticles upon Li insertion/extraction. With these contributions, Bi@NC exhibits excellent cycling stability and rate capacity compared to bare Bi nanoparticles or their simple composites with carbon. This study provides a new approach for fabricating high volumetric energy density LIBs.

Ultrastructural observations of human epidermal melanocytes cultured on polyethylene terephthalate film.

OBJECTIVE: To assess the application of polyethylene terephthalate film as a supporting material of cultured human epidermal melanocytes and to observe the ultrastructure of human epidermal melanocytes in vitro. METHODS: Human epidermal melanocytes were isolated from 7- to 14-years old children foreskins and were cultured in M254 culture medium containing human melanocyte growth supplement. Cultured melanocytes were purified via a differential trypsinization method. Purified melanocytes were cultured on a film and prepared for transmission electron microscopy. RESULTS: In comparing with the cellular supporting materials polyvinylidene chloride and cellophane, human epidermal melanocytes only attached and grew on polyethylene terephthalate film. Melanocytes grown on polyethylene terephthalate film maintained an intact shape, and retained special ultrastructures characteristic of melanocytes such as dendrites. CONCLUSIONS: Polyethylene terephthalate film proved to be an ideal cellular supporting material for the cultivation of human epidermal melanocytes. Ultrastructure of melanocytes showed melanosomes are transferred both from the tip and middle section of dendrites.