As one of the most promising cathode materials for sodium-ion batteries, sodium-ion layered oxide has the advantages of high capacity and low cost, which makes sodium-ion batteries have great application prospects in large-scale static energy storage. However, their commercial development has been limited due to poor electrochemical cycle stability and air stability. Compared with traditional polycrystalline layered oxides, single-crystalline layered oxides are characterized by high mechanical strength, low specific surface, and high taping density, and thus can effectively improve the cycling stability of layered oxides and enhance their comprehensive performance. The basic structure types of layered oxides of sodium-ion batteries are introduced in the paper.The synthesis methods of single-crystal layered oxides of sodium-ion batteries that have been reported so far are also reviewed and the advantages and disadvantages of various synthesis methods are analyzed. Besides, the improvement of single-crystal morphology on comprehensive performance is described and the research status of single-crystal layered oxides in sodium-ion batteries is presented with an outlook of the future development of single-crystal layered oxides for sodium-ion batteries.

Transporting hydrogen?blended natural gas (HBNG) through existing natural gas pipelines can significantly reduce the cost of hydrogen transportation. To evaluate the risk of HBNG pipeline leakage, a high?pressure pipeline small?hole leakage model and a Gaussian plume model are combined, taking into account the lifting height caused by the initial momentum of the jet. The calculation results of the Gaussian plume model are compared with the existing experimental data. Then, the influence of the hydrogen mixing ratio, pipeline pressure, wind speed, and leakage hole diameter on the explosion risk area caused by the leakage of the natural gas pipeline is analyzed. The research results indicate that the calculation results of the Gaussian plume model are in good agreement with the experimental data. The hydrogen mixing ratio is approximately linearly negatively correlated with the maximum distance from the methane hazardous area, and linearly positively correlated with the maximum distance from the hydrogen hazardous area. The maximum distance between methane and hydrogen hazardous areas is approximately linearly positively correlated with pipeline pressure, negatively correlated with wind speed, and approximately proportional to the diameter of the leakage hole.