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The inferior reversibility of the formation/decomposition of the lithium peroxide (Li2O2) and its insolubility and insulation features result in poor energy efficiency and limited durability of state-of-the-art Li–O2 batteries. Herein, we elaborately designed sisal-like CoSe2 nanowires enriched with Se vacancies (VSe-CoSe2) anchored on a scaffold of magnetron-sputtered N-doped carbon cloth (N-CC) to address the above challenges. The synergistic coupling of vacancy regulation with interfacial interaction can be used to tune the ability to adsorb active oxygen and intermediate species and enhance the interfacial electron transfer during oxygen redox reactions. Experimental results demonstrate that the VSe-CoSe2@N-CC-based Li–O2 battery demonstrates a substantially decreased overpotential (∼0.56 V) and extraordinary durability (over 955 h). This work indicates that the synergistic coupling of vacancy modulation and interface interaction is a promising strategy for effectively enhancing the comprehensive performance of Li–O2 batteries, which provide prospective insights into the exploration of next-generation highly efficient metal–air batteries. [ABSTRACT FROM AUTHOR]

Designing and constructing an effective and efficient oxygen electrode plays a pivotal role in the successful development of lithium‐oxygen (Li−O2) batteries. Herein, NiCo2S4 nanorod arrays directly grown on carbon textile (R‐NCS/CT) is successfully prepared by a simple hydrothermal route and systematically studied for the first time as a free‐standing electrode in Li−O2 electrochemical systems. The R‐NCS/CT based Li−O2 battery achieves a low charge overpotential (1.17 V), a high discharge capacity (4506 mA h g−1), and improved cycle life (500 cycles). These improvements can be attributed to both, the unique architecture design of the electrodes for facilitating the rapid oxygen diffusion and electrolyte penetration and superior activity of oxygen electrode kinetics of NiCo2S4 nanorods. To some extent, the optimization of the catalyst composition and design of the electrode structures provide a guidance for further development of more stable and efficient cathodes for Li−O2 batteries. Array of sunshine: NiCo2S4 nanorod arrays grown on carbon textile (R‐NCS/CT) are successfully fabricated and systematically studied as a free‐standing cathode for Li−O2 batteries. The Li−O2 battery based on the R‐NCS/CT cathode shows excellent stability and long cycle life, owing to the high catalytic activity of NiCo2S4 and the unique structural design of the cathode. [ABSTRACT FROM AUTHOR]

Braided wire rope is vital for stringing conductors with tension in overhead transmission lines. Its structure and characteristics determine the safety and reliability of the stringing construction. Torque generated in this process can cause an uneven stress distribution, ultimately causing the wire rope to fail. This study analyzes distributions of stress and deformation in braided wire rope subjected to torsional loading. A geometric model for YS9-8 × 19 braided wire rope was established, and finite element analysis was performed on the model in different twisting directions. The simulation results show that the wires in the strands have the tendency to be screwed tightly and are in a stretched state when the lay direction of the strand coincides with its torsion direction. However, when the lay and torsion directions are opposite, the wires in the strands tend to unwind and are in a compressed state. At the same torsional angle, different torques can be generated at a particular cross-section along different twisting directions. This shows that braided wire rope has better anti-twist characteristics when twisted clockwise compared to when twisted anticlockwise. Finally, a torsion test was conducted on the braided wire rope. The results show that the change in the torque curve with respect to the torsional angle is in good agreement with the simulation results. [ABSTRACT FROM AUTHOR]

Exploring oxygen electrodes with superior bifunctional catalytic activity and suitable architecture is an effective strategy to improve the performance of lithium-oxygen (Li-O 2 ) batteries. Herein, the internal electronic structure of Ni 2 P is regulated by heteroatom Co doping to improve its catalytic activity for oxygen redox reactions. Meanwhile, magnetron sputtering N-doped carbon cloth (N-CC) is used as a scaffold to enhance the electrical conductivity. The deliberately designed Co-Ni 2 P on N-CC (Co-Ni 2 P@N-CC) with a typical 3D interconnected architecture facilitates the formation of abundant solid-liquid-gas three-phase reaction interfaces inside the architecture. Furthermore, the rational catalyst/substrate interfacial interaction is capable of inducing a solvation-mediated pathway to form toroidal-Li 2 O 2 . The results show that the Co-Ni 2 P@N-CC based Li-O 2 battery exhibits an ultra-low overpotential (0.73 V), enhanced rate performance (4487 mA h g -1 at 500 mA g -1 ) and durability (stable operation over 671 h). The pouch-type battery based on the Co-Ni 2 P@N-CC flexible electrode runs stably for 581 min in air without obvious voltage attenuation. This work verifies that heterogeneous atom doping and interface interaction can remarkably strengthen the performance of Li-O 2 cells and thus pave new avenues towards developing high-performance metal-air batteries.

The degradation of oxygen electrodes caused by oxygen species in lithium-oxygen (Li-O2) batteries deteriorates their energy efficiency and cyclability and seriously hinders their commercial application. To achieve high energy efficiency and long-term cycle life, gradient-porous ultrathin FeCo2S4 nanosheets on Ni foam (FeCo2S4@Ni) were deliberately designed as a noncarbonaceous freestanding oxygen electrode for Li-O2 batteries. Notably, the gradient-porous structure in FeCo2S4@Ni can offer sufficient active sites as well as mitigate polarization caused by the mass transfer during discharge and charge. The synergistic effect of the two transition metals, Fe2+ and Co3+, optimizes their d-band electronic structure and enhances the intrinsic activity of the oxygen electrode. Benefiting from the above merits, the FeCo2S4@Ni based Li-O2 battery demonstrates greatly increased discharge capacity (8001 mA h g-1), improved rate capability (with a high capacity of 4401 mA h g-1 at 500 mA g-1), and enhanced cycling stability (with a low overpotential of below 1 V after 109 cycles). Our work demonstrates that the battery performance can be improved by regulating the structure and composition of the oxygen electrode and provides a promising strategy for developing high performance Li-O2 batteries.

Catalysts with high performance are urgently needed in order to accelerate the reaction kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in lithium-oxygen (Li-O 2 ) batteries. Herein, utilizing thermodynamically metastable Ti atoms on the Ti 3 C 2 Tx MXene nanosheet surface as the nucleation site, oxygen vacancy-rich TiO 2 nanoparticles were in situ fabricated on Ti 3 C 2 Tx nanosheets (V-TiO 2 /Ti 3 C 2 Tx) and used as the oxygen electrode of Li-O 2 batteries. Oxygen vacancy (Vo) can boost the migration rate of electrons and Li + as well as act as the active sites for catalyzing the ORR and OER. Based on the above merits, V-TiO 2 /Ti 3 C 2 Tx-based Li-O 2 battery shows improved performance including the ultralow overpotential of 0.21 V, high specific capacity of 11 487 mA h g -1 at a current density of 100 mA g -1 , and excellent round-trip efficiency (93%). This work proposes an effective strategy for researching high-performance oxygen electrodes for Li-O 2 batteries via introducing Vo-rich oxides on two-dimensional MXene.