Lithium–sulfur batteries (LSBs) are regarded as promising candidates for the next‐generation energy storage devices owing to their high‐theoretical capacity (1675 mAh g−1) and affordable cost. However, several limitations of LSBs such as the lithium polysulfide shuttle, large volume expansion, and low electrical conductivity of sulfur need to be resolved for practical applications. To address these limitations, herein, a multidimensional architectured hybrid (Co@CNT/nG), where Co3O4 nanoparticles are encapsulated into three‐dimensional (3D) porous N‐doped reduced graphene oxide interconnected with carbon nanotube (CNT) branches, is synthesized through a simple pyrolysis method. The synergistic effect achieved through the homogeneously distributed and encapsulated Co3O4 nanoparticles, the interconnected CNT branches, and the 3D hierarchical porous structure and N‐doping of Co@CNT/nG significantly suppresses the shuttle effect of lithium polysulfides and enhances the conversion redox kinetics for the improved sulfur utilization. We validate this effect through various measurements including symmetric cells, Li2S nucleation, shuttle currents, Tafel slopes, diffusion coefficients, and post‐mortem analyses. Importantly, Co@CNT/nG‐70S‐based LSB cells achieve a high‐specific capacity of 1193.1 mAh g−1 at 0.1 C and a low capacity decay rate of 0.030% per cycle for 700 cycles at 5 C, delivering a high areal capacity of 5.62 mAh cm−2 even with a loading of 6.5 mg cm−2.
This paper reviews the site investigation field data and access work performed between 2016 and 2019 in the study area located close to Gun-dong mine. The research was aimed at defining the cause of sinkholes and their relationship with the underlying karstic limestone bedrock and nearby mining activities. Only a limited number of small sinkholes appeared in 2014, 2016, and 2018 in the agricultural land close to the limestone mine. The previously open pit mine started its underground operations in 2007. Since then, the mine has developed, and is now comprised of, large underground excavations at several levels below the surface. The studies carried out concluded that the appearance of sinkholes may be related to a general lowering of the groundwater table because of nearby agricultural and mining activities and also due to over-extraction of water due to increased urban use. Whilst these are the best determinations, this paper identifies missing elements of the previous investigations mentioned above, some issues with the interpretation of poorly prepared borehole logs and the improper preservation of borehole cores. The authors make recommendations for a systematic approach for implementation of an investigation strategy. This paper concludes that the appearance of sinkholes is a natural phenomenon, developing over geological time. However, human intervention contributes to sinkhole formation, which in urban areas may result in human, property, and economic losses. A better understanding, based on a methodical approach and suitable technologies, can determine the causes of sinkholes and can lead to the formulation of solutions and the implementation of economically and socially acceptable mitigation measures.
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