RESUMEN
As the classic cathode material, lithium cobalt oxide (LiCoO2, LCO) suffers from severe structural and interfacial degradation at voltage >4.5 V, which induces fast capacity decay of the cells. Herein, we adopt a simple and effective method, doping aluminum (Al) cations in precursors, to improve the structural stability of LCO and systematically investigate the effect of Al doping on the electrochemical performances. Doping in precursors rather than bulk particles is beneficial to realize uniform Al ions distribution. Even at 4.5 V charging voltage, the LCO/graphite pouch cells with high Al doping levels (8500 ppm) deliver initial and reversible discharge capacities of 386 and 369 mAh after 500 cycles, respectively. The capacity retention is as high as 95.5%. When the cutoff voltage reaches 4.55 V, the pouch cell maintains 79.0% of the first-cycle discharge capacity after 500 cycles. With optimized electrolyte, the pouch cell realizes 87.3% of the initial discharge capacity after 500 cycles at 45 °C. Moreover, the thermal safety performance of the pouch cells with Al doping is promising. Our work displays an excellent inspiration for developing high-voltage, long-cycle, and safe LCO cathode for commercial lithium-ion batteries.
RESUMEN
Exploring an active and cost-effective electrocatalyst alternative to carbon-supported platinum nanoparticles for alkaline hydrogen evolution reaction (HER) have remained elusive to date. Here, we report a catalyst based on platinum single atoms (SAs) doped into the hetero-interfaced Ru/RuO2 support (referred to as Pt-Ru/RuO2), which features a low HER overpotential, an excellent stability and a distinctly enhanced cost-based activity compared to commercial Pt/C and Ru/C in 1 M KOH. Advanced physico-chemical characterizations disclose that the sluggish water dissociation is accelerated by RuO2 while Pt SAs and the metallic Ru facilitate the subsequent H* combination. Theoretical calculations correlate with the experimental findings. Furthermore, Pt-Ru/RuO2 only requires 1.90 V to reach 1 A cm-2 and delivers a high price activity in the anion exchange membrane water electrolyzer, outperforming the benchmark Pt/C. This research offers a feasible guidance for developing the noble metal-based catalysts with high performance and low cost toward practical H2 production.
RESUMEN
The rational design of novel high-performance cathode materials for sodium-ion batteries is a challenge for the development of the renewable energy sector. Here, a new sodium-deficient NASICON phosphate, namely Na3.40 â¡0.60 Co0.5 Fe0.5 V(PO4 )3 , demonstrating the excellent electrochemical performance is reported. The presence of Co allows a third Na+ to participate in the reaction thus exhibiting a high reversible capacity of ≈155 mAh g-1 in the voltage range of 2.0-4.0 V versus Na+ /Na with a reversible single-phase mechanism and a small volume shrinkage of ≈5.97% at 4.0 V. 23 Na solid-state nuclear magnetic resonance (NMR) combined with ex situ X-ray diffraction (XRD) refinements provide evidence for a preferential Na+ insertion within the Na2 site. Furthermore, the enhanced sodium kinetics ascribed to Co-substitution is also confirmed in combination with electrochemical impedance spectroscopy (EIS), galvanostatic intermittent titration technique (GITT), and theoretical calculation.
RESUMEN
Here, we report a facile approach to fabricate large area ordered arrays of TiO2 hierarchical nanostructures through space-confined seeding and growth on inverted pyramid templates. The mechanisms of space-confined seeding and growth have been systematically explored and studied. The drying TiO2 seed precursor solution prefers to accumulate on the narrow structures including the centre and edges of the inverted pyramid structures, which facilitates to reduce the free energy of the precursor solution surface and form crystal seeds. Followed by hydrothermal treatment, selective growth of TiO2 hierarchical nanostructures on desirable locations, such as only on the centre, only on the edges, or on the entire surface of the inverted pyramid templates, can be achieved. In addition, the growth temperature, duration and solvents affect the morphology of TiO2 hierarchical nanostructures. This work may provide a universal approach to obtain ordered arrays of metal oxide (e.g. ZnO and MnO2, etc.) nanostructures for applications in optics, electrics, energy, and catalysis.
RESUMEN
Genetic studies and gene localization for human dermatoglyphs are currently ongoing. However, the inheritance modes of various genetic traits are not well understood because of the complexity of dermatoglyph genetics. The study of admixed populations can contribute to the understanding of population genetic traits of dermatoglyphs. Here, we present the dermatoglyphic characteristics of Kam and Liujia Han, and the admixed population consisting of these two parent populations. The characteristics of the admixed population do not always fall in the same ranges as the parent population characters but do seem to be biased to Kam or Liujia parent populations, depending on sex and ethnicity of parents. The total frequencies of different fingerprint types do not differ among these populations, but several of the quantitative traits and the palm true pattern frequencies do significantly differ between admixed and parent populations. The simple arch fingerprint frequency decreases significantly in the admixed population in comparison with parent populations while both simple whorl fingerprint frequency and finger ridge counts increase significantly. True pattern frequency of the span area of interdigital III and IV areas on right hands and the radial-loop frequency of the right index fingers in the admixed populations are consistent with their matrilineal population. These dermatoglyphic changes may result from increased heterozygosity in the admixed population. The genetic modes of these changes may be relatively simple and will be useful for future dermatoglyph genetic studies.
