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Bridge damage detection has attracted much attention recently. Most studies on damage detection of the high-speed railway (HSR) bridge neglect the effect of the interlayer connection between the railway track and bridge. This paper proposes a damage detection method for the HSR bridge using response-based sensitivity analysis of high-speed trains. The HSR bridge is modeled as a spatial track–bridge system, in which the fasteners, sleepers and track slabs are modeled as one viscoelastic layer. The responses of multiple vehicles are merged to overcome the critical issue that the length of response data recorded by a high-speed vehicle moving over the bridge is too short to perform the sensitivity analysis. Numerical studies demonstrate that the proposed method is capable to detect damages of the track–bridge system with different train speed, car-body mass, irregularity grade and the interlayer connection properties. By using the signal merging method and the averaged response from multiple train trips, the proposed method is robust to high speed and measurement noise. The damage on the bridge beam and the interlayer connection can be well-identified. It is also found that increasing the car-body mass, damping ratio of the track–bridge system, damping coefficient of interlayer connection could improve the efficiency of damage detection. [ABSTRACT FROM AUTHOR]

Layered metal oxides are promising cathode materials for sodium-ion batteries (SIBs) due to their high theoretical specific capacity and wide Na+ diffusion channels. However, the irreversible phase transitions and cationic/anionic redoxes cause fast capacity decay. Herein, P2-type Na0.67Mg0.1Mn0.8Fe0.1O2 (NMMF-1) cathode material with moderate active Fe3+ doping has been designed for sodium storage. Uneven Mn3+/Mn4+distribution is observed in NMMF-1 and the introduction of Fe3+ is beneficial for reducing the Mn3+ contents both at the surface and in the bulk to alleviate the Jahn–Teller effect. The moderate Fe3+/Fe4+ redox can realize the best tradeoff between capacity and cyclability. Therefore, the NMMF-1 demonstrates a high capacity (174.7 mAh g−1 at 20 mA g−1) and improved cyclability (78.5% over 100 cycles) in a wide-voltage range of 1.5–4.5 V (vs. Na+/Na). In-situ X-ray diffraction reveals a complete solid-solution reaction with a small volume change of 1.7% during charge/discharge processes and the charge compensation is disclosed in detail. This study will provide new insights into designing high-capacity and stable layered oxide cathode materials for SIBs. [ABSTRACT FROM AUTHOR]

Parasitic reactions are responsible for continuous performance loss during the normal operation and storage of lithium-ion batteries, particularly for those using nickel-rich cathode materials. Among many contributors, residual Li2CO3 on the surface of nickel-rich cathodes plays a detrimental role in promoting parasitic reactions, and hence accelerates the performance loss of those cathode materials. In this work, a wet impregnation process was utilized to convert the detrimental Li2CO3 and LiOH impurities into a beneficial functional surface coating comprising phosphates. Specifically, hydro-phosphates were used as the functional surface modification agents to mitigate the detrimental effect of surface residuals. The best electrochemical performance was achieved by modifying LiNi0.6Mn0.2Co0.2O2 with a diluted dihydro-phosphate solution (pKa = 7.2), while the metal cation had a negligible impact on the electrochemical performance. This work provides a cheap and simple method for enabling the high performance of nickel-rich cathodes. [ABSTRACT FROM AUTHOR]

Rational design and construction of highly efficient nonprecious electrocatalysts for oxygen reduction and alcohols oxidation reactions (ORR, AOR) are extremely vital for the development of direct oxidation alkaline fuel cells, metal‐air batteries, and water electrolysis system involving hydrogen and value‐added organic products generation, but they remain a great challenge. Herein, a bifunctional electrocatalyst is prepared by anchoring CuS/NiS2 nanoparticles with abundant heterointerfaces and sulfur vacancies on graphene (Cu1Ni2‐S/G) for ORR and AOR. Benefiting from the synergistic effects between strong interfacial coupling and regulation of the sulfur vacancies, Cu1Ni2‐S/G achieves dramatically enhanced ORR activity with long term stability. Meanwhile, when ethanol is utilized as an oxidant for AOR, an ultralow potential (1.37 V) at a current density of 10 mA cm−2 is achieved, simultaneously delivering a high Faradaic efficiency of 96% for ethyl acetate production. Cu1Ni2‐S/G also exhibits catalytic activity for other alcohols electrooxidation process, indicating its multifunctionality. This work not only highlights a viable strategy for tailoring catalytic activity through the synergetic combination of interfacial and vacancies engineering, but also opens up new avenues for the construction of a self‐driven biomass electrocatalysis system for the generation of value‐added organic products and hydrogen under ambient conditions. [ABSTRACT FROM AUTHOR]